DE102009056844B4 - Engine exhaust emission control device - Google Patents

Abstract

An engine exhaust emission control device having a collector for collecting particulates contained in exhaust gas and performing a regeneration process for removing the particulates accumulated in the collector using a heating mechanism, the engine exhaust emission control apparatus comprising: a reduction rate determining unit (53) which is for the determination is formed as to whether a reduction rate (ΔY) of the particles at a predetermined time interval (T1, T2) during the regeneration process is equal to or greater than a threshold value (a1, a2); anda regeneration control unit (52) configured to variably control the heating mechanism for burning the particulate matter in accordance with a determination result of the decrease rate determination unit (53), characterized in that the decrease rate determination unit (53) determines the decrease rate (ΔY) with respect to the second threshold value (a2) at a time interval (T2) which is shorter than a time interval (T1) for the determination of the reduction rate (ΔY) with respect to the first threshold value (a1).

Description

The present invention relates to an engine exhaust emission control device including a collector for collecting particulates contained in exhaust gas.

Nowadays vehicles such as Motor vehicles, a collector for filtering and collecting particles contained in the exhaust gas from an engine, in particular a diesel engine, as part of an exhaust emission control device for cleaning the exhaust gases from the engine. The collector is typically made up of a filter called a diesel particulate filter (DPF), and since the accumulation of particulates reduces the filtration and collection efficiency, it is necessary to forcibly perform a regeneration process to remove the accumulated particulates and regenerate the Filter to restore it to its original state.

In such a regeneration process for a diesel particulate filter, an amount of particulate accumulation in the diesel particulate filter is generally estimated, and when the particulate accumulation amount is equal to or greater than a certain amount, the temperature of the exhaust gas serving as the regeneration gas for regenerating the diesel particulate filter is increased so that the particulates accumulated in the diesel particulate filter are forcibly burned.

For example, the JP 2004-300 973 A a technique of temporarily increasing the discharge temperature at predetermined time intervals and performing a diesel particulate filter regeneration operation when the discharge temperature downstream of the diesel particulate filter becomes equal to or greater than a predetermined determination value.

However, when the particulates accumulated in the diesel particulate filter are forcibly burned, there are problems that the combustion of all the accumulated particulates requires a longer regeneration period and may affect the fuel efficiency and that raising the regeneration gas temperature too much to shorten the regeneration period causes the life of the diesel particulate filter from heat damage.

In this regard, the JP 2005-307 746 A a technique of performing forced regeneration in an area of high particulate combustion efficiency instead of executing forced regeneration in an area of low particulate combustion efficiency, focusing on the fact that the particulate combustion rate increases as the amount of particulate accumulation increases, thereby providing the amount required for forced regeneration Shorten the duration.

According to the above JP 2005-307 746 A Although the diesel particulate filter regeneration period can be shortened, the amount of particulate accumulation in the diesel particulate filter is kept constant at an amount equal to or greater than a certain amount. Although deterioration in fuel efficiency can be prevented, since some particulate matter always remains in the diesel particulate filter, there is a risk that the engine output will be degraded and the technique may not always be effective.

In a case in which a forced regeneration of the diesel particulate filter is carried out in this way, if the regeneration period is shortened by increasing the regeneration gas temperature, the service life may be impaired due to heat damage, on the other hand, if a certain amount of particulate is left without combustion by In this way, to shorten the regeneration period, the engine output can be decreased. In the conventional technique, it is difficult to improve the fuel efficiency by effectively burning the particulate matter to shorten the regeneration period without reducing the life of the diesel particulate filter.

The DE 10 2006 009 921 A1 relates to a method for operating a particle filter arranged in an exhaust gas region of an internal combustion engine and a device for performing the method. If necessary, the particle filter is regenerated from the stored particles, the particle filter being heated upstream of the particle filter for regeneration by influencing the exhaust gas temperature. During the regeneration of the particle filter, the exhaust gas temperature is set to a predetermined exhaust gas temperature setpoint value which depends on at least one parameter of the particle filter during the regeneration.

The present invention has been made in view of the above situation, and the object of the present invention is to provide an engine exhaust emission control device capable of improving fuel economy when a collector for collecting particulates contained in exhaust gas is subjected to a forced regeneration by removing the particles without impairment burned effectively over the lifetime of the collector.

A solution to this problem is provided according to the invention with an engine exhaust emission control device as set out in claim 1. Advantageous further developments of the invention are specified in subclaims 2 to 5.

In particular, an engine exhaust emission control device according to the present invention has a collector for collecting particulates contained in exhaust gas, and performs a regeneration process for removing particulates accumulated in the collector using a heating mechanism. The engine exhaust emission control device includes: a decrease rate determination unit configured to determine whether a decrease rate of the particulate matter at a predetermined time interval during the regeneration process is equal to or greater than a threshold value; and a regeneration control unit configured to variably control the heating mechanism for burning the particulates depending on a determination result of the decrease rate determination unit.

According to the present invention, when the collector is forcibly regenerated to collect particulates contained in the exhaust gas, the fuel efficiency can be improved by effectively burning the particulates without impairing the life of the collector.

Preferred developments of the invention are specified in the subclaims.

• 1 ein Gesamtblockdiagramm eines Motors;
• 2 ein Blockdiagramm, das sich auf eine Dieselpartikelfilter-Regenerationssteuerung bezieht;
• 3 eine Ansicht zur Erläuterung einer Partikelverminderungsbestimmung bei einem jeweiligen spezifizierten Zeitintervall;
• 4 eine Ansicht zur Erläuterung der Partikelverminderungsbestimmung innerhalb eines spezifizierten Zeitintervalls; und
• 5 ein Flussdiagramm einer Dieselpartikelfilter-Regenerationssteuerungsroutine.

The invention and developments of the invention are explained in more detail below with reference to the drawings of an exemplary embodiment. In the drawings show:

• 1 an overall block diagram of an engine;
• 2 Fig. 4 is a block diagram relating to diesel particulate filter regeneration control;
• 3 FIG. 11 is a view for explaining a particulate matter reduction determination at each specified time interval;
• 4th a view for explaining the particulate reduction determination within a specified time interval; and
• 5 Fig. 3 is a flowchart of a diesel particulate filter regeneration control routine.

An embodiment of the present invention is described below with reference to the drawings. This embodiment is shown in 1 to 5 illustrated.

In 1 denotes the reference number 1 an engine, which in the present embodiment is a diesel engine with a common rail fuel injection system. An upper portion of a combustion chamber of the engine 1 has openings to an inlet port 2 and an outlet port 3 as well as an injector inserted into it 4th to inject fuel in the common rail system, which accumulates high pressure fuel supplied from a high pressure pump, not shown, into the combustion chamber of each cylinder. The reference number 5 denotes an intake valve, and the reference number 6th denotes an exhaust valve.

An inlet passage 7th is with an upstream portion of the inlet port 2 connected and communicated with this, and an inlet chamber 8th is in the inlet passage 7th educated. There is also an air purifier 9 at an air inlet of the intake passage 7th intended. Immediately downstream from the air cleaner 9 is an intake air quantity sensor 11 inserted for detecting an intake air amount.

An outlet passage 10 is with the downstream part of the outlet port 3 connected and communicates with it. In the outlet passage 10 are a diesel oxidation catalyst (DOC) 12 primarily for oxidizing hydrocarbons (HC) in exhaust gas through catalysis and a diesel particulate filter (DPF) 13 arranged as a collector for collecting particulates such as soot (dust, carbon dust), soluble organic matter (SOF) and sulfate (SO4) in the exhaust gas on the downstream side of the diesel oxidation catalyst 12 serves.

In the upstream and downstream areas of the diesel particulate filter 13 that is in the exhaust passage 10 is arranged are a temperature sensor 14a for detecting the inlet temperature of the diesel particulate filter 13 (the temperature of the diesel particulate filter 13 supplied exhaust gas) and a temperature sensor 14b for detecting the outlet temperature of the diesel particulate filter 13 (the temperature of the exhaust gas immediately downstream from the diesel particulate filter 13 ) intended.

Further, there are the upstream and downstream areas of the diesel particulate filter 13 with a differential pressure sensor 15th for sensing a pressure difference between the pressure at the inlet of the diesel particulate filter 13 and the pressure at the outlet of the diesel particulate filter 13 connected and communicate with it.

The diesel oxidation catalyst 12 is formed, for example, by arranging noble metal such as platinum and palladium, metal oxide such as alumina, or the like on a surface of a ceramic substrate made of a cordierite honeycomb structural body or the like. In addition, there is the diesel particulate filter 13 For example, formed by forming a heat-resistant ceramic material such as cordierite with a honeycomb structure in which a number of cells serving as gas channels and inlets or outlets of these cells are alternately sealed. When exhaust gas in the diesel particulate filter 13 flows, the particulates contained in the exhaust gas are collected, and they gradually accumulate, while the exhaust gas in the course of the passage through porous partition walls of the diesel particulate filter 13 flows downstream.

Furthermore, the reference number denotes 50 an engine control unit (ECU) for electronically controlling the engine 1 ; the ECU is primarily composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface or the like, and other components including peripheral circuits such as an A / D converter Include a timer, a counter, various logic circuits, or the like.

The ECU 50 become detection signals from the respective sensors 11 , 14a , 14b and 15th fed. Further, the ECU also receives a signal that is one from a crank angle sensor 16 detected engine speed, a signal received from an accelerator opening amount sensor 17th Indicates detected accelerator opening extent, as well as signals from other sensors, not shown, supplied.

Furthermore, the ECU 50 is connected to an on-board network (not shown) using a communication protocol such as CAN (Controller Area Network) and exchanges various kinds of information by sending and receiving data to and from other ECUs associated with the on-board network and which are, for example, a transmission ECU for controlling a transmission and a brake ECU for controlling a brake.

The ECU 50 calculates the fuel injection amount, injection timing, or the like based on the signals from the various sensors that detect engine operating conditions and the various control information input via the on-board network, and controls the operation of the engine 1 . With this engine control the ECU determines 50 during normal driving depending on the engine speed on the basis of the signal from the crank angle sensor 16 and a load based on the signal from the accelerator opening amount sensor 17th the fuel injection amount and the fuel injection timing with reference to a map or the like, and controls the injection operation of high pressure fuel from the injector 4th in the pattern of a multi-stage injection process before and after the piston top dead center in a combination, for example, of pre-injection processes and main injection processes, in order to stabilize the combustion and reduce exhaust emissions.

The ECU also performs 50 a regeneration process for regenerating the diesel particulate filter 13 at a predetermined time in parallel with the normal engine control. During the regeneration process of the diesel particulate filter 13 it is a process for regenerating a filter through the targeted removal of gas that contains incompletely burned components from the engine with combustion (oxidation) of these components with the diesel oxidation catalytic converter 12 and burning the in the diesel particulate filter 13 accumulated particles using the heat generated by the combustion.

In the regeneration process, the operation is shifted to a forced regeneration operating mode, which differs from normal operation, in order to carry out a delayed injection in a multi-stage injection process, such as delaying the main injection at a point in time before and after top dead center or a post-injection in close to bottom dead center of the piston, in this way the temperature of the diesel particulate filter 13 supplied exhaust gas (regeneration gas) is increased and in the diesel particulate filter 13 collected and accumulated particulates are burned and removed.

For this reason, the ECU includes 50 as a function of each unit related to the diesel particulate filter regeneration process, a particulate accumulation rate estimation unit 51 , a diesel particulate filter regeneration control unit 52 and a particulate reduction rate determining unit 53 like this in 2 is shown.

The ECU 50 estimates a particulate accumulation rate Y in the diesel particulate filter 13 and starts a diesel particulate filter regeneration process when the estimated particulate accumulation rate Y becomes greater than a predetermined reference value. After starting the diesel particulate filter regeneration process, the ECU sets 50 sets a decreased state of the particulate accumulation rate Y every specified time interval, and controls the diesel particulate filter regeneration operation based on whether the decrease degree of Particle accumulation rate Y is equal to or greater than a threshold value.

In particular, the particulate accumulation rate estimation unit estimates 51 the particulate accumulation rate Y based on an engine operating condition, a pressure difference between the upstream side and the downstream side of the diesel particulate filter 13 , an exhaust gas temperature or the like. For example, a map of particulate discharge amounts based on engine speeds and fuel injection amounts based on experiments or simulations is generated in advance, and the particulate accumulation rate estimation unit 51 can estimate the particle accumulation rate depending on this map.

Or the differential pressure sensor 15th detects a pressure difference between the pressure at the inlet and the pressure at the outlet of the diesel particulate filter 13 , and the particulate accumulation rate estimation unit 51 can estimate the particle accumulation rate as a function of the pressure difference.

If the particulate accumulation rate is estimated on the basis of an outlet temperature, due to the fact that there is a heat capacity of the diesel particulate filter 13 is changed according to the particulate accumulation amount, the particulate accumulation rate can be estimated by checking the amount of increase in the exhaust gas temperature. In other words, it is with regard to the diesel particulate filter 13 with a small amount of particle accumulation, the heat capacity is also relatively low, so that the temperature is increased relatively early by the exhaust gas introduced.

On the other hand, when the particulate accumulation amount becomes large, the heat capacity of the diesel particulate filter also increases 13 , and the temperature rise caused by the introduced exhaust gas becomes relatively slow. Because the rise in temperature in the diesel particulate filter 13 in the outlet temperature at the outlet of the diesel particulate filter 13 reflects the outlet temperature at the outlet of the diesel particulate filter 13 from the temperature sensor 14b detected to determine the exit temperature rise rate θv therefrom; on the basis of this rate, the rate of particle accumulation can be estimated.

For example, as illustrated in the following equation (1), in order to eliminate the influence of a heat capacity other than the heat capacity of the accumulated particulates, that is, the heat capacity excluding the diesel particulate filter 13 , a difference between an exit temperature rise rate θv0 in a case where the particulate accumulation rate is zero (after the end of the diesel particulate filter regeneration process) and an exit temperature rise rate maximum value θvmax detected during operation, and a conversion coefficient k is multiplied by the obtained difference to obtain the particle accumulation rate Y therefrom. $$\text{Y}=\text{k}\times \left(\mathrm{\theta }\text{v}0-\mathrm{\theta }\text{vmax}\right)$$

Here, the conversion coefficient k is a coefficient for converting the difference in the exit temperature rise rates into an amount of particulate accumulation obtained from a map based on the engine speeds and the accelerator opening amounts and the like. The conversion coefficient k is set to be larger as the engine speed increases and the accelerator opening amount increases.

The above-described particulate accumulation rate estimating processes can be used independently or in combination with each other. The particle accumulation rate estimation unit 51 compares the estimated particulate accumulation rate Y with a predetermined reference value and outputs the comparison result to the diesel particulate filter regeneration control unit 52 from.

When the particulate accumulation rate Y becomes larger than the reference value, the diesel particulate filter regeneration control unit increases 52 the temperature of the diesel particulate filter 13 supplied exhaust gas (regeneration gas) to a value higher than that in the normal operation using the delay of the main injection, the post injection or the like, and starts the regeneration process for burning the in the diesel particulate filter 13 accumulated particles and thus to regenerate the filter. When the particulate accumulation rate Y has then substantially reached zero, the diesel particulate filter regeneration control unit ends 52 the diesel particulate filter regeneration process.

At the start of the DPF regeneration process, an output value of a controlled variable (such as a delay amount of the main injection and a fuel injection amount of the post injection) applied in the DPF regeneration control is sent to the injector 4th is given by a map provided for the diesel particulate filter regeneration process for controlled variables, separately from a map for controlled variables for normal operation.

In other words, it becomes when the particulate accumulation rate Y becomes larger than that Reference value, and the determination is made to start the diesel particulate filter regeneration process, switched from the map for the normal operation to the map for the diesel particulate filter regeneration process, and thereby the controlled output variable using the map for the diesel particulate filter regeneration process on the basis the engine speed and the engine load.

The value of the controlled variable, which is stored in the map for the diesel particulate filter regeneration process, is determined in advance, taking into account the capacity properties of the diesel particulate filter 13 or the like is predetermined on the basis of simulations or experiments in such a way that the exhaust gas temperature at the inlet of the diesel particulate filter 13 assumes a predetermined temperature which is preferred for the diesel particulate filter regeneration process.

During the diesel particulate filter regeneration process, the particulate reduction rate determining unit 53 sets a rate at which the particulate accumulation rate Y becomes lower every predetermined time in the course of the particulate combustion process by means of high-temperature regeneration gas (particulate reduction rate ΔY).

When according to the determination result by the particulate reduction rate determination unit 53 the particulate matter reduction rate ΔY is low, the diesel particulate filter regeneration control unit increases 52 the temperature of the regeneration gas within a range equal to or less than a maximum control temperature, which is to avoid heat damage to the diesel particulate filter 13 is predetermined, and specifies the controlled variable of the diesel particulate filter regeneration control for increasing the combustion of the particulates.

The particulate reduction rate determining unit 53 determines the particulate reduction rate ΔY with respect to the particulate accumulation rate Y at every predetermined time interval. According to the present exemplary embodiment, the determination of the particle reduction rate ΔY is carried out in two stages: in a first time interval T1 and a second time interval T2, which is shorter than the first time interval T1.

When determining in the first time interval T1 monitored in the in 2 The particle reduction rate determination unit 53 shows a difference between a previous particle accumulation rate Yt-1 and a current particle accumulation rate Yt as the particle reduction rate ΔY at every first time interval T1 (e.g. 20 s) and determines whether the particle reduction rate ΔY is equal to or greater than a first threshold value a1 or not.

The threshold value a1 is a determination value that is used for determining whether the diesel particulate filter regeneration process is carried out following a certain control target and that in the diesel particulate filter 13 accumulated particles can be reduced by a planned default amount, this threshold value being based on experiments or simulations depending on the engine type and the specification of the diesel particulate filter 13 is specified in advance.

When the determination result in the first time interval T1 indicates that ΔY a1, it is determined that the amount of particulate matter in the diesel particulate filter is made 13 is successfully reduced and regeneration control continues.

If, on the other hand, in the in 3 The result shown indicates that ΔY <a1 when, in other words, the particulate reduction rate of the diesel particulate filter 13 is less than a target value, the target temperature of the regeneration gas is increased in order to increase the particle combustion. For example, with respect to the controlled variable of the diesel particulate filter regeneration control, a correction value is used to raise the temperature at the inlet of the diesel particulate filter 13 by a predetermined amount of temperature is predetermined on the basis of experiments and simulations, and the controlled variable corrected from the correction value is used to carry out fuel injections (main injections and post-injections). In order to achieve a rapid change in the temperature at the inlet of the diesel particulate filter 13 To prevent this, it is preferable to gradually change the controlled variable to the corrected value.

After correcting the controlled variable, it is determined whether the particulate reduction rate ΔY monitored at each time interval T2, which is shorter than the first time interval T1, is equal to or greater than a second threshold value a2. For the particle reduction rate ΔY determined in the second time interval T2, the difference between the previous particle reduction rate Yt-1 and the current particle reduction rate Yt or a value obtained by a smoothing process or an averaging process of the respective differences is used.

The second threshold value a2 is a determination value for avoiding a risk of damage due to rapid combustion of particulates in the diesel particulate filter 13 , the second threshold a2 being greater than the first Threshold value a1 is given (a2> a1). Therefore, when ΔY a2, the controlled variable of the diesel particulate filter regeneration control is reset to the initial value to stop the increase in the regeneration gas temperature and damage the diesel particulate filter 13 to prevent.

On the other hand, if ΔY <a2 and the risk of damaging the diesel particulate filter 13 is low, the particle reduction rate ΔY monitored at each first time interval T1 is again compared with the threshold value a1. If ΔY <a1 and the particles have not yet been sufficiently burned, the controlled variable is additionally corrected in order to further increase the regeneration gas temperature.

This series of operations is carried out repeatedly until ΔY a1 and the particulate combustion is increased sufficiently as long as ΔY <a2 and there is no risk of damage to the diesel particulate filter 13 consists. The additional correction for the controlled variable can be specified smaller than the first correction, and subsequent additional corrections can be specified smaller in steps.

As with this configuration, the burning and removal of the in the diesel particulate filter 13 accumulated particulate matter can be efficiently carried out without excessively increasing the regeneration gas temperature, an improvement in the fuel efficiency can be achieved while avoiding an extension of the regeneration period while reducing the life of the diesel particulate filter 13 can be avoided due to heat damage.

The particulate matter reduction determination in the first time interval T1 and the particulate matter reduction determination in the second time interval T2 can take place at different times or at the same time. In other words, the particulate matter reduction determination result in the first time interval T1 can be shifted to the particulate matter reduction determination in the second time interval T2 or the particulate reduction determination in the second time interval T2 can be carried out constantly, and the particulate matter reduction determination in the first time interval T1 can be carried out as a result of the aggregation of the determination results in the second time interval T2 respectively.

In the following, a program flow for the diesel particulate filter regeneration described above is described with reference to a flowchart in FIG 5 explained. It should be noted that 5 illustrates a diesel particulate filter regeneration control routine executed upon starting the diesel particulate filter regeneration process.

This diesel particulate filter regeneration control routine is first in a first step S1 checks whether the current particle accumulation rate is reduced compared to a previous particle accumulation rate at an earlier specified point in time. More specifically, using the first time interval T1 as the specified time interval, the particulate reduction rate ΔY is calculated by subtracting the current particulate accumulation rate Yt from the previous particulate accumulation rate Yt-1 at an earlier time interval and determining whether the particulate reduction rate ΔY is equal to or greater than the first threshold a1.

As a result, when the particulate accumulation rate ΔY is equal to or greater than the threshold value a1, it is determined that the diesel particulate filter regeneration is progressing successfully according to the schedule, so that the diesel particulate filter regeneration process is carried out in one step S7 is continued. On the other hand, when the particulate matter reduction rate ΔY has not reached the first threshold value a1, the process goes from step S1 with one step S2 continues, and it is determined whether that of the temperature sensor 14a detected current diesel particulate filter inlet temperature is equal to or lower than the maximum limit temperature for protecting the diesel particulate filter 13 .

As a result, when the current diesel particulate filter inlet temperature is higher than the maximum limit temperature, the controlled variable becomes in one step S3 is maintained unchanged, and the diesel particulate filter regeneration process is performed in step S7 continued. The other hand is in one step S2 if a currently preset diesel particulate filter target inlet temperature is equal to or lower than the maximum limit temperature, the process of step S2 with one step S4 continued, and in the step S4 and subsequent steps, the controlled variable is corrected to carry out an operation for switching to an increase in the regeneration gas temperature.

The process then proceeds in one step S5 continued, the extent of the decrease in particulate accumulation rates every other time interval T2 is monitored, and it is determined whether the particulate matter reduction rate ΔY is found to be equal to or greater than the second threshold value a2 and equal to or greater than a specified value.

If ΔY <a2, in the step S5 determined that there is no risk of damage due to rapid combustion of the particulates during an increase in the regeneration gas temperature, and the process returns to step S1 to perform an operation depending on the magnitude relationship between the particulate reduction rate ΔY and the first threshold value a1, as described above.

If a preferred particulate matter reduction rate is not achieved at the first time interval T1 as a result of these processes, the controlled variable is additionally corrected within a range that is equal to or less than the maximum limit temperature for increasing the regeneration gas temperature, so that the combustion of the in the diesel particulate filter 13 accumulated particles can be increased.

If on the other hand in the step S5 the relation ΔY ≥ a2 holds, the process proceeds from the step S5 with one step S6 and the diesel particulate filter regeneration control controlled variable is reset to an initial setting, the process then going to step S1 returns. By changing the controlled variable of the diesel particulate filter regeneration control to the initial value, the increase in the regeneration gas temperature is stopped, causing damage to the diesel particulate filter 13 can be prevented due to rapid combustion of particles.

If after the processes described above, the regeneration in step S7 continues, it is done in one step S8 determines whether the particulate accumulation rate becomes equal to or less than a final determination value that can be used for determining that that in the diesel particulate filter 13 remaining particle components are almost zero.

If the particulate accumulation rate Y is still higher than the final determination value, then the process returns to the step S1 to continue the operations outlined above. When the particulate accumulation rate Y is equal to or less than the final determination value, the particulate regeneration process is completed and the operational routine returns to the normal operation.

Since, according to the present exemplary embodiment, during the regeneration process of the diesel particulate filter 13 the controlled variable for the regeneration process for burning and removing particulates is corrected in determining the particulate reduction rate, the regeneration gas temperature and the regeneration process period can be appropriately and efficiently controlled.

With this configuration, it is possible to effectively maintain a particulate collection performance without impairing the service life of the diesel particulate filter 13 or there is a decrease in engine output; fuel consumption can also be improved.

The above embodiment has been explained using a diesel engine as the engine; however, the present invention may find application in other engines that utilize exhaust gas with particulate matter therein, such as a cylinder injection type gasoline engine.

List of reference symbols

1

engine

2

Inlet connection

3

Outlet connection

4th

Injector

5

Inlet valve

6th

outlet valve

7th

Inlet passage

8th

Inlet chamber

9

air cleaner

10

Outlet passage

11

Intake air quantity sensor

12

Diesel oxidation catalyst

13

Diesel particulate filter

14a, 14b

Temperature sensors

15th

Differential pressure sensor

16

Crank angle sensor

17th

Accelerator opening amount sensor

50

Engine control unit (ECU)

51

Particle Accumulation Rate Estimation Unit

52

Diesel particulate filter regeneration control unit

53

Particle reduction rate determining unit

Claims (5)

An engine exhaust emission control device comprising a collector for collecting particulates contained in the exhaust gas and a regeneration process for removing the particulates accumulated in the collector using a A heating mechanism, the engine exhaust emission control device comprising: a decrease rate determining unit (53) configured to determine whether a decrease rate (ΔY) of the particulates at a predetermined time interval (T1, T2) during the regeneration process is equal to or greater than one as a threshold value (a1, a2); and a regeneration control unit (52) configured to variably control the heating mechanism for burning the particulates depending on a determination result of the reduction rate determination unit (53), characterized in that the reduction rate determination unit (53) is a determination of the Reduction rate (ΔY) with respect to the second threshold value (a2) at a time interval (T2) which is shorter than a time interval (T1) for the determination of the decrease rate (ΔY) with respect to the first threshold value (a1). Engine exhaust emission control device according to Claim 1 characterized in that upon determining that the decrease rate (ΔY) is equal to or greater than the first threshold value (a1), the regeneration control unit (52) continues the regeneration process without changing the control of the heating mechanism. Engine exhaust emission control device according to Claim 1 or 2 characterized in that when the decreasing rate (ΔY) is less than the first threshold value (a1), the regeneration control unit (52) controls the heating mechanism so that the temperature is increased. An engine exhaust emission control device according to any one of Claims 1 to 3 characterized in that upon determining that the decrease rate (ΔY) is equal to or greater than the second threshold value (a2), the regeneration control unit (52) stops the heating control of the heating mechanism. An engine exhaust emission control device according to any one of Claims 1 to 4th wherein the heating control of the heating mechanism is carried out by delay control of main injection timing or post injection control after the main injection process in a multi-stage injection process.

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