JPH0559931A - Exhaust purifying device of diesel engine - Google Patents

Abstract

PURPOSE:To judge regeneration inferiority of a filter and eliminate exhaust particles remaining after regeneration process properly. CONSTITUTION:Respective cumulated amounts of exhaust particles after/before a filter is regenerated, are estimated by a cumulated amount estimating circuit 41. When regeneration inferiority is judged from the difference between both cumulated amounts by a regeneration condition detecting circuit 50, an exhaust throttle valve 11 and a bypass valve 19 are closed by an exhaust particle eliminating circuit 51. Then, the exhaust throttle valve 11 is opened/closed bit by bit, and high pressure exhaust is allowed to flow into a filter little by little to eliminate the exhaust particles forcibly. When failure of forcibly eliminate is judged by a failure judging circuit 53, exhaust is stopped flowing into the filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust emission control device for a diesel engine equipped with a filter for collecting exhaust particulates.

[0002]

2. Description of the Related Art Exhaust particles such as carbon are contained in the exhaust gas of a diesel engine. As one of the methods for removing the exhaust particle from the exhaust gas, a filter is provided in the exhaust passage of the engine and the exhaust gas is filtered by this filter. Conventionally, a method of collecting exhaust particulate matter by passing it is well known. In this case, exhaust particles adhere to the vicinity of the exhaust gas inflow part of the filter and gradually accumulate, but if the amount of accumulation increases, the exhaust pressure increases and the engine performance is adversely affected. It is necessary to periodically perform a regeneration process of a filter that removes by burning or the like.

If the regeneration process is not carried out with the accumulated amount increasing, when the engine reaches a high load and high speed region, the exhaust pressure rises sharply and the accumulated exhaust fine particles suddenly separate at once. The so-called blow-off phenomenon occurs. If a sudden blow-off occurs, a large amount of exhaust particulates will be contained in the exhaust gas released into the atmosphere, and the exhaust gas will be emitted in a noticeable visible black smoke state, which will adversely affect the surroundings. There is a risk that Further, due to the sudden blow-off, the exhaust pressure suddenly drops and the engine performance is deteriorated, which imposes a burden on the engine and is not preferable in terms of durability of the engine.

As the filter regeneration processing, there is a method of burning exhaust particulates by an electric heater provided immediately before the filter, or a method of igniting fuel injected from a fuel injection valve to burn the exhaust particulates. Kaisho 59
-20513 and JP-A-59-122721).

[0005]

By the way, when the amount of accumulated exhaust particulate matter collected on the filter increases and the filter is regenerated, the collected exhaust particulate matter is not always completely burned. However, the exhaust particulates may not be completely burned and may remain in the filter depending on the accumulation state and the components of the exhaust particulates and the operating state of the engine during regeneration. If a large amount of exhaust particulates remain in the filter without being burnt after the regeneration process, the blow-off phenomenon described above may occur.

The present invention has been made to solve such a conventional problem, and an object thereof is to prevent an excessive amount of exhaust particulates from being deposited on a filter and to prevent exhaust gas deposited on the filter. The purpose of this is to prevent rapid separation of the particles due to an increase in exhaust pressure.

[0007]

In order to achieve the above object, an exhaust emission control device for a diesel engine according to a first aspect of the present invention includes a filter provided in an exhaust passage of the engine for collecting exhaust particulates in exhaust gas, and the filter. A deposition amount detection means for detecting the deposition amount of the collected exhaust particulates, and when the deposition amount detected by the deposition amount detection means becomes a predetermined value or more, burns the exhaust particulates collected by the filter. Means for regenerating the filter, exhaust pressure control means for preventing exhaust gas from flowing into the filter and increasing exhaust pressure upstream of the filter, and regeneration means before and after regeneration by the regeneration means. In step 1, the combustion amount of the exhaust particulates is obtained based on the deposition amount of the exhaust particulates detected by the deposition amount detecting means. A reproduction state determination means for determining for, when the reproduction state determination means determines that the filter aplastic, behavior-exhaust inlet blocked by the exhaust pressure control means
It is characterized in that it has an exhaust particulate removal means for controlling the exhaust pressure upstream of the filter by repeating the release and gradually removing the exhaust particulate accumulated on the filter by the exhaust pressure.

Further, an exhaust emission control device for a diesel engine according to a second aspect of the present invention detects a filter provided in an exhaust passage of the engine for collecting exhaust particulates in exhaust gas and a deposition amount of the exhaust particulates collected by the filter. Based on the operating state detection means for detecting the operating state of the engine, the operating state detection means for detecting the operating state of the engine, the amount of exhaust particulate matter detected by the deposition amount detection means and the operating state detection means, A separation occurrence condition detecting means for detecting the condition for the accumulated exhaust particulates to separate, and when the separation condition of the exhaust particulates detected by the separation occurrence condition detecting means becomes a predetermined frequency or more, is collected by the filter. And a regeneration means for regenerating the filter by burning the exhaust particulates and an exhaust passage upstream of the filter for preventing exhaust gas from flowing into the filter. Exhaust pressure control means for increasing the air pressure, and the combustion amount of exhaust particulates is obtained based on the deposition amount of exhaust particulates detected by the deposition amount detection means before and after regeneration by the regeneration means, and the combustion amount is less than or equal to a predetermined value. If the regeneration state judgment means determines that the regeneration of the filter is defective, and if the regeneration state determination means determines that the regeneration of the filter is defective, the exhaust pressure control means repeatedly performs the operation / cancellation of the exhaust gas inflow prevention to upstream the filter. And an exhaust particulate removing means for gradually removing the exhaust particulate accumulated on the filter by the exhaust pressure.

[0009]

According to the exhaust gas purifying apparatus of the first aspect of the present invention, when the amount of exhaust particulate matter deposited on the filter detected by the deposit amount detecting means exceeds a predetermined value, the regenerating means removes the exhaust particulate matter collected on the filter. After the combustion, the filter is regenerated, and after this regeneration, when the regeneration state determination means determines that the regeneration is defective, based on the accumulated amount of exhaust particulate matter detected by the deposition amount detection means before and after regeneration, the exhaust pressure control means transfers to the filter. Repeat the operation and release of the exhaust gas inflow prevention. Blocking the inflow of exhaust increases the exhaust pressure upstream of the filter,
When the inflow prevention is released, the exhaust particulates deposited on the filter are released due to this increased exhaust pressure, but by repeatedly performing the operation and release of the exhaust inflow prevention, the release is gradually performed, and a single sudden release does not occur. Avoided.

According to the second aspect of the exhaust gas purifying apparatus for a diesel engine, the separation occurrence condition detecting means is based on the accumulation amount of exhaust particulate matter detected by the accumulation amount detecting means and the operating state detecting means and the operating state of the engine. When the condition for removing the exhaust particulates is detected, and when the condition for removing the exhaust particulates reaches a predetermined number of times or more, the regeneration means burns the exhaust particulates collected by the filter to regenerate the filter, and after the regeneration, the accumulation is performed. When the regeneration state determination means determines that the regeneration is defective based on the amount of exhaust particulate accumulation before and after regeneration detected by the amount detection means, the exhaust pressure control means operates to prevent the inflow of exhaust gas into the filter.
Repeat the release.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an exhaust emission control device for a diesel engine according to an embodiment of the present invention. A filter 5 made of porous ceramic or the like is provided in the middle of an exhaust passage 3 connected to a diesel engine body 1 mounted on a vehicle. When the exhaust gas passes through the filter 5, exhaust gas particulates such as carbon in the exhaust gas are collected and attached to the filter 5.

Immediately after the downstream side of the filter 5, the filter 5
A temperature sensor 6 for detecting the exhaust temperature on the downstream side of the filter 5 is provided.
An electric heater 7 as a regenerating means for burning the exhaust particulates collected in the filter is provided, and an exhaust passage 3 which is normally open is appropriately closed upstream thereof to prevent the exhaust gas from flowing into the filter 5. An exhaust throttle valve 11 as an exhaust pressure control means having a drive device 9 for increasing the exhaust pressure is provided. A pressure sensor 1 for detecting the pressure in the exhaust passage 3 upstream of the filter 5 is provided upstream of the exhaust throttle valve 11.
3, the exhaust passage 3 on the upstream side of the pressure sensor 13 communicates with the exhaust passage 3 on the downstream side of the filter 5 by a bypass passage 15, and the normally closed bypass passage 15 is opened in the bypass passage 15. By-pass valve 1 provided with drive device 17 for causing exhaust gas to flow into bypass passage 15
9 is provided.

A failure lamp 20 for reporting an abnormality of the present device to a driver is provided in the interior of a vehicle equipped with an engine, a heater 7, a drive device 9 for the exhaust throttle valve 11, a bypass valve 19
The drive device 17 and the failure lamp 20 are a rotation sensor 23 and a control lever sensor 25 for detecting the operating state of the engine, a pressure sensor 13 for detecting the pressure of the exhaust passage 3,
Also, it operates or stops according to an output signal from a control unit 21 including a microcomputer which receives each signal input of the temperature sensor 6 for detecting the exhaust gas temperature. Here, in the present embodiment, the rotation sensor 23 and the control lever sensor 25 constitute an operating state detecting means.

Next, the structure of the control unit 21 will be described. FIG. 2 is a block diagram of the present embodiment. The operating condition detection circuit 27 includes a rotation sensor 23 for detecting the engine speed Ne and a control lever opening C /
In response to the input of the detection signal from the control lever sensor 25 for detecting L, the engine speed Ne and the control lever opening C / L are successively accumulated amount calculation circuit 29 and blow generation condition determination circuit 31 as a separation generation condition detection means. Signal is output to.

The deposit amount calculation circuit 29 receives the signal from the operating condition detection circuit 27 based on the exhaust particulate emission map from the engine set as shown in FIG.
Also, the amount of exhaust particulate matter discharged from the engine per unit time is searched according to the control lever opening C / L, and the retrieved value is multiplied by the exhaust particulate collection efficiency in the filter 5 to be integrated. The accumulated amount of exhaust particulates collected in 5 is obtained, and a signal is output to the blow generation condition determination circuit 31, the regeneration control circuit 32, and the regeneration timing determination circuit 33. The blow generation condition determination circuit 31 determines the blow generation region corresponding to the deposition amount of the exhaust particulates determined by the deposition amount calculation circuit 29 based on the blow generation region map set as shown in FIG. 4, and the operating condition detection circuit 27. Based on the engine speed Ne and the control lever opening C / L, which are input as a signal from the engine, it is determined whether or not it is within the blow generation region, that is, whether or not the exhaust particulate is easily separated from the filter 5 in a large amount. Here, in the blow occurrence region map of FIG. 4, the blow occurrence region is set from the high load and high rotation side when the deposition amount of exhaust particulates is small, and from the low load and low rotation side when the deposition amount is large. Therefore, the blow generation condition can be accurately determined according to the amount of exhaust particulates deposited. When it is judged that the blow generation condition is satisfied, the blow generation condition judgment circuit 31 is in a state where a large amount of exhaust particulate is easily separated from the filter 5, so a signal is output to the exhaust throttle output circuit 35 and the bypass output circuit 37 to output the exhaust throttle valve. 11 is closed and the bypass valve 19 is opened to perform blow avoidance processing for bypassing exhaust gas to the filter 5, and at the same time, a signal is output to the regeneration timing determination circuit 33.

When the blow generation condition determination circuit 31 does not determine that the blow generation condition is satisfied, the regeneration timing determination circuit 33 determines whether or not the deposition amount of exhaust particulates calculated by the deposition amount calculation circuit 29 is equal to or greater than a predetermined value, and a predetermined value is determined. When it is more than the value, it is judged to be the reproduction time. On the other hand, when the blow occurrence condition determination circuit 31 determines that the blow occurrence condition is present, the proportion of the blow occurrence condition determined within the predetermined time of, for example, 1 minute immediately before is calculated as the blow occurrence frequency, and the blow occurrence frequency is set to the predetermined value. When it is more than the value, it is judged to be the reproduction time. When it is determined that it is the regeneration time, the regeneration time determination circuit 33 outputs a signal to the regeneration control circuit 32 and the accumulation amount estimation circuit 41. In this embodiment, the deposit amount estimating circuit 41 and the deposit amount calculating circuit 29 described above constitute the deposit amount detecting means. Reproduction control circuit 32
Receives a signal input from the reproduction timing determination circuit 33,
A signal is output to the regeneration output circuit 43 to energize the electric heater 7 to burn the exhaust particulates to perform the regeneration processing of the filter 5, and the deposition amount of the exhaust particulates calculated by the deposition amount calculation circuit 29 at the start of the regeneration processing. Memorize The exhaust gas temperature detection circuit 45, during the regeneration process of the filter 5,
It receives a detection signal from the temperature sensor 6 that detects the exhaust gas temperature T on the downstream side of the filter 5, and outputs the signal to the regeneration control circuit 32. The regeneration control circuit 32 obtains the combustion amount of exhaust particulates in the filter 5 based on the exhaust temperature T,
The combustion amount is compared with the deposition amount of the filter 5 stored at the start of the regeneration process, and when the combustion amount matches the deposition amount, it is determined that the regeneration has been sufficiently performed, and the regeneration process is ended. At the end of the regeneration process, a signal is output from the regeneration control circuit 32 to the accumulation amount estimation circuit 41. When the regeneration timing determination circuit 33 determines that it is not the regeneration timing, a signal is output to the exhaust throttle output circuit 35 and the bypass output circuit 37 to open the exhaust throttle valve 11 and close the bypass valve 19. The exhaust gas into the filter 5.

The exhaust pressure detection circuit 47 receives a detection signal from the pressure sensor 13 which detects the pressure P in the exhaust passage 3 on the upstream side of the filter 5, and outputs the pressure P to the sequential deposition amount estimation circuit 41 as a signal. .. Further, the operating condition detection circuit 27 sequentially outputs the engine speed Ne and the control lever opening C / L to the deposition amount estimation circuit 41 as a signal. When receiving the signal for starting regeneration of the filter 5 from the regeneration timing determination circuit 33, the deposition amount estimation circuit 41 upstream side of the filter 5 for each operating condition when a predetermined amount of exhaust particulate matter set as shown in FIG. 5 is deposited. Based on the reference pressure P ₀ map of, the engine speed Ne at that time when a signal is input from the operating condition detection circuit 27
And a reference pressure P ₀ at the time of depositing a predetermined amount of exhaust particulates according to the throttle opening C / L, and the reference pressure P ₀ and the actual operation under the same operating condition signaled from the exhaust pressure detection circuit 47. The estimated deposition amount G1 is estimated from the ratio to the pressure P of the above, and the estimated deposition amount G1 is stored in the deposition amount storage circuit 49. Further, when the accumulation amount estimating circuit 41 receives a regeneration end signal from the regeneration control circuit 32, the reference pressure P ₀ under the operating condition at that time, which is signaled from the operating condition detecting circuit 27, is obtained from the map of FIG. Search for this reference pressure P
_The estimated deposition amount G2 is estimated from the ratio between ₀ and the actual pressure P at that time, which is signaled from the exhaust pressure detection circuit 47,
The estimated deposition amount G2 is output to the regeneration state determination circuit 50 serving as a regeneration state determination means and stored in the deposition amount storage circuit 49.

When the regeneration state determination circuit 50 receives a signal of the estimated deposition amount G2 of exhaust particulates of the filter 5 after the regeneration process from the deposition amount estimation circuit 49, the estimated deposition amount G2 and the deposition amount storage circuit 49 The stored estimated amount G1 before the regeneration process is compared to determine whether or not the regeneration is favorably performed. In this embodiment, G1 × K>
If it is G2, it is judged that the reproduction was performed well, and conversely,
If G1 × K ≦ G2, it is determined that the reproduction is incomplete. Here, the value of the coefficient K is K = 0.9.

When the estimated deposition amount G2 after regeneration is 0.9 times or more of the estimated deposition amount G1 before regeneration, that is, when the regeneration is defective, the regeneration state determination circuit 50 causes the exhaust particulate removal circuit as exhaust particulate removal means. Signal is output to. Upon receiving a signal input from the regeneration state determination circuit 50, the exhaust particle removal circuit 51 first outputs a signal to the exhaust throttle output circuit 35 and the bypass output circuit 37 in order to forcibly remove the exhaust particles deposited on the filter 5. Then, both the exhaust throttle valve 11 and the bypass valve 19 are closed to increase the pressure in the exhaust passage upstream of the exhaust throttle valve 11. Next, bypass valve 1
With the valve 9 closed, the exhaust throttle valve 11 is repeatedly opened and closed in small increments to intermittently inject high-pressure exhaust gas into the filter 5 little by little. As a result, exhaust particulates that have accumulated on the filter 5 without being burned by the regeneration process are gradually removed from the filter 5. When the number of inflows of the exhaust gas into the filter 5 reaches a predetermined number, a signal is output to the exhaust throttle output circuit 35 to open the exhaust throttle valve 11 to complete the forced removal of the exhaust particulates, and a signal to the deposition amount estimation circuit 41. Output.

Upon receipt of a signal indicating the completion of the forced removal of exhaust particulates from the exhaust particulate removal circuit 51, the deposition amount estimation circuit 41 estimates the estimated deposition amount G3 of exhaust particulates on the filter 5 after the completion of the forced removal to determine a failure. The signal is output to the circuit 53.

When the failure determination circuit 53 receives the estimated deposition amount G3 signal after the forced removal, it inputs the estimated deposition amount G3 and the estimated deposition amount G2 stored in the deposition amount storage circuit 49 after the regeneration process and before the forced removal. Compare and determine if forced removal was successful. In this embodiment, G2 ×
If L> G3, it is judged that the forced removal was successfully performed,
On the contrary, if G2 × L ≦ G3, it is determined that the forced removal is incomplete. Here, the value of the coefficient L is L = 0.7.

When the estimated deposition amount G3 after the forced removal is 0.7 times or more of the estimated deposition amount G2 before the forced removal, that is, when it is determined that the forced removal is incomplete, the filter 5 is exhausted any more. If the exhaust particles are continued to be collected by collecting the exhaust particles, the exhaust particles may not be removed and the deposition amount becomes excessively large, which may increase the exhaust pressure and continuously load the engine. Even if the accumulated exhaust particulates are burnt, the temperature of the filter 5 at the time of regeneration is too high and the service life of the filter 5 is likely to be shortened because the amount of accumulation is excessive. For this reason, the failure determination circuit 53 determines that some abnormality has occurred, and the exhaust throttle output circuit 35.
A signal is output to the bypass output circuit 37 and the exhaust throttle valve 1
The valve 1 is closed and the bypass valve 19 is opened to bypass the exhaust gas to the filter 5, and a signal is output to the failure lamp 20, which is lit to report the abnormality to the driver.

Next, the control operation of the exhaust emission control system for a diesel engine constructed as above will be described with reference to the flow charts shown in FIGS.

First, the operating condition detection circuit 27 detects the engine speed Ne and the control lever opening C / L from the rotation sensor 23 and the control lever sensor 25, and the exhaust pressure detection circuit 47 detects the pressure sensor 13 from the pressure sensor 13 to the upstream side of the filter 5. The pressure P in the exhaust passage 3 (hereinafter abbreviated as exhaust pressure) is read (step 101). Next, the accumulation amount calculation circuit 29
However, based on the engine speed Ne, the control lever opening C / L at this time, and the exhaust gas discharge amount map of FIG. 3, the deposition amount of the exhaust gas particles collected by the filter 5 is calculated (step 103), Blow occurrence condition judgment circuit 31
However, based on the exhaust particulate matter deposition amount obtained in step 103 and the blow generation area map of FIG.
It is judged whether or not the engine speed Ne and the control lever opening C / L read in step 101 are within the obtained region, that is, whether or not the blow is generated (step 1).
05).

When it is determined in step 105 that the blow condition is not satisfied, the regeneration timing determination circuit 33 determines whether the accumulated amount of exhaust particulates obtained in step 103 has reached a predetermined value, that is, the regeneration timing. If it is determined that the regeneration time is reached, the regeneration process of the filter 5 is performed (step 200). If not at the regeneration time, the exhaust throttle valve 11 is opened and the bypass valve 19 is closed to remove the exhaust gas from the filter 5. (Step 109).

On the other hand, if it is determined in step 105 that the blow condition is satisfied, the blow condition determination circuit 31 causes the exhaust throttle valve 1 to continue until it is determined that the blow condition is not satisfied.
1 is closed and the bypass valve 19 is opened to bypass the exhaust gas to the filter 5 (step 111),
The regeneration timing determination circuit 33 determines whether or not the blow occurrence frequency stored in step 115, which will be described later, is equal to or greater than a predetermined value, that is, the regeneration timing (step 113). The blow occurrence frequency is a ratio that is a blow occurrence condition within a predetermined time, and regeneration is required when the blow occurrence frequency is high.

When the reproduction process of the filter 5 is not performed,
After calculating and storing the blow occurrence frequency (step 11
5) and end. In the present embodiment, 20 ms
This control is repeated every ec.

Next, the control operation of the regeneration process of the filter 5 will be described.

First, according to the engine speed Ne and the control lever opening C / L read in step 101,
The accumulation amount estimation circuit 41 uses the reference pressure map of FIG. 5 to determine the reference pressure P when a predetermined amount of exhaust particulates are accumulated on the filter 5.
₀ is obtained, and the estimated accumulation amount G1 before regeneration is obtained from the ratio of the reference pressure P ₀ and the actual exhaust pressure P read in step 101.
After calculating (step 201), the electric heater 7 is energized to perform a regeneration process (step 203). During the regeneration process, the regeneration control circuit 32 obtains the combustion amount of exhaust particulates, that is, the regeneration amount from the exhaust temperature T on the downstream side of the filter 5 detected by the temperature sensor 6 (step 205). The difference between the calculated amount of exhaust particulate matter before regeneration and the calculated amount is calculated, and the electric heater 7 is continuously energized until the difference reaches a predetermined value (step 207). In the present embodiment, the predetermined value is set to 0 and the electric heater 7 is continuously energized until all the exhaust particulates can burn.

When the amount of regeneration reaches a predetermined amount, the electric heater 7
Is stopped (step 209) and the reproduction process is ended (step 211).

When the regeneration process of the filter 5 is completed, the engine speed Ne, the control lever opening C / L and the exhaust pressure P at that time are read (step 213), and the accumulation amount estimation circuit 41 reads the estimated accumulation amount after regeneration. G2 is calculated (step 215), and the regeneration state determination circuit 50 determines whether or not the value obtained by multiplying the estimated accumulation amount G1 before regeneration calculated in step 201 by the coefficient K is larger than this G2. (Step 217). In this embodiment, the value of this coefficient K is K = 0.9. When G2 is equal to or more than the value obtained by multiplying G1 by K, 0.9 times or more of the accumulated amount of exhaust particulates before the regeneration of the filter 5 remains in the filter 5 even after the regeneration, so that the regeneration is not successful. Judge that it is sufficient.

When the regeneration is insufficient, the exhaust particulate removal circuit 51 forcibly removes the exhaust particulates from the filter 5 (step 300). When the forced removal of the exhaust particulates is completed, the engine speed Ne at that time is reached. , Read control lever opening C / L and exhaust pressure P (step 21
9), the estimated deposition amount G after the deposition amount estimation circuit 41 forcibly removes
3 is calculated (step 221). Then, the failure determination circuit 53 determines whether or not the value obtained by multiplying the estimated deposition amount G2 after regeneration calculated before the forced removal in step 215 by the coefficient L is larger than this G3 (step 223).
In this embodiment, the value of this coefficient L is L = 0.7. When G3 is greater than or equal to the value obtained by multiplying G2 by L, 0.7 times or more of the amount of exhaust particulates accumulated before the forced removal of the filter 5 remains in the filter 5 even after the forced removal. The removal is insufficient and it is determined that there is a failure (step 400).

Next, the control operation for the forced removal of the filter 5 by the exhaust particulate removal circuit 51 will be described.

First, the exhaust throttle valve 11 and the bypass valve 19
Is closed (step 301) and the timer 1 is operated (step 303). When the timer 1 has passed the set time and the exhaust passage 3 upstream of the exhaust throttle valve 11 is in a high pressure state, the bypass throttle valve 19 is closed and the exhaust throttle valve 11 is opened (step 305). Forcefully remove some of the exhaust particles. In this state, the timer 2 is operated to measure for a predetermined time (step 307), and after the measurement, the number of forced removals is integrated (step 309). Next, it is determined whether or not the number of times of forced removal has been reached (step 311), and if it is determined that the number of times of forced removal has not been reached, the process returns to step 301 and the above operation is repeated until the number of times is reached. When the predetermined number of times is reached, almost all exhaust particulates will be removed.
As described above, in the forced removal of the filter 5 in this embodiment, the exhaust throttle valve 11 is repeatedly opened and closed in small increments so that the exhaust gas in a high pressure state is intermittently introduced into the filter 5, so that the filter 5 collects it. A large amount of exhausted fine particles are not released at a time, and even if regeneration is insufficient, exhaust gas can be suppressed from being emitted in a visible black smoke state, and the exhaust pressure suddenly increases. There is no fear that the engine performance will deteriorate as a result.

Next, the control operation at the time of failure by the failure determination circuit 53 will be described.

If the forced removal in step 300 is insufficient and it is determined that there is an abnormality, the exhaust throttle valve 11 is closed and the bypass valve 19 is opened to bypass all the exhaust gas to the filter 5. (Step 401), the failure lamp is turned on (Step 403). As described above, in this embodiment, when the regeneration process is insufficient and the forced removal is insufficient, the failure determination circuit 53 determines that the abnormality occurs,
Since the exhaust gas is bypassed to the filter 5, it is possible to prevent the accumulation amount of exhaust particulates in the filter 5 from becoming excessive, the exhaust pressure to rise, and the burden on the engine from increasing. Further, since the amount of exhaust particulates deposited on the filter 5 does not become excessively large, combustion of exhaust particulates in an excessively large state and the resulting excessive rise in temperature of the filter 5 can be prevented, and the life of the filter 5 is shortened. I won't let you. Further, when a failure occurs, the failure lamp 20 provided in the vehicle compartment is turned on, so that the driver can immediately recognize the abnormality and can immediately respond to the failure.

For forced removal, for example, as shown in FIG. 11, the exhaust throttle valve 11 and the bypass valve 19 are closed (step 351), and the exhaust pressure detected by the pressure sensor 13 provided upstream of the exhaust throttle valve is detected. When P becomes equal to or higher than a predetermined value (step 353), the exhaust throttle valve 11 is opened to forcibly remove a part of exhaust particulates (step 355), and when the exhaust pressure P becomes equal to or lower than a predetermined value (step 355). It is also possible to carry out by a method of integrating the number of times (step 357) (step 359) and repeating opening and closing of the throttle valve up to a predetermined number of times (step 361).

[0038]

As described above, according to the present invention, when the amount of exhaust particulates deposited on the filter reaches a predetermined value or more, or the condition for separating exhaust particulates from the filter reaches a predetermined number of times or more. At this time, the filter is regenerated, and if it is determined that the filter has not been regenerated after this regeneration, the operation to cancel the inflow of exhaust gas to the filter and the release are repeated. It will gradually disengage due to pressure, and it is possible to prevent exhaust from being emitted in the state of visible black smoke at the time of defective reproduction,
In addition, deterioration of engine performance due to a sudden decrease in exhaust pressure can be avoided. Furthermore, since the accumulation amount of exhaust particulates on the filter after the defective regeneration is prevented from becoming excessive, when the filter is regenerated by burning the exhaust particulates, the life of the filter is shortened by increasing the combustion temperature of the filter. It can prevent the deterioration.

[Brief description of drawings]

FIG. 1 is an overall view of an exhaust emission control device for a diesel engine according to an embodiment of the present invention.

FIG. 2 is a block diagram of the present embodiment.

FIG. 3 is an exhaust particulate emission map from an engine.

FIG. 4 is a blow generation area map.

FIG. 5 is a reference pressure map on the filter upstream side for each operating condition when a predetermined amount of exhaust particulate matter is deposited.

FIG. 6 is a main flowchart of the present embodiment.

FIG. 7 is a filter regeneration flowchart.

FIG. 8 is a filter regeneration flowchart.

FIG. 9 is a forced removal flowchart.

FIG. 10 is a failure flow chart.

FIG. 11 is another forced removal flowchart.

[Explanation of symbols]

5 Filter 7 Electric Heater (Regeneration Means) 11 Exhaust Throttle Valve (Exhaust Pressure Control Means) 23 Rotation Sensor (Operating State Detecting Means) 25 Control Lever Sensor (Operating State Detecting Means) 29 Deposition Amount Calculation Circuit (Deposition Amount Detection Means) 31 Blow generation condition determination circuit (separation generation condition determination means) 41 Deposition amount estimation circuit (deposition amount detection means) 50 Regeneration state determination circuit (regeneration state determination means) 51 Exhaust particulate removal circuit (exhaust particulate removal means)

Claims (2)

[Claims] 1. A filter provided in an exhaust passage of an engine for collecting exhaust particulates in exhaust gas, a deposition amount detecting means for detecting a deposition amount of exhaust particulates collected by the filter, and a deposition amount detecting means. When the amount of accumulation detected by the filter becomes a predetermined value or more, a regeneration means for regenerating the filter by burning the exhaust particulates collected by the filter, and the exhaust gas to the filter provided in the exhaust passage upstream of the filter Exhaust pressure control means for preventing the inflow of exhaust gas and increasing the exhaust pressure upstream of the filter, and the combustion amount of exhaust particulate matter based on the accumulation amount of exhaust particulate matter detected by the accumulation amount detection means before and after regeneration by the regeneration means. It is determined that when the combustion amount is less than or equal to a predetermined value, the regeneration state determining means determines that the regeneration of the filter is defective, and the regeneration state determining means determines that the regeneration of the filter is defective. The exhaust pressure control means repeatedly controls the release of the exhaust gas to control the exhaust pressure upstream of the filter and gradually removes the exhaust particulates accumulated on the filter by the exhaust pressure. Exhaust gas purification device for diesel engines. 2. A filter provided in an exhaust passage of an engine for collecting exhaust particulates in exhaust gas, a deposition amount detecting means for detecting a deposition amount of exhaust particulates collected by the filter, and an operating state of the engine. The condition for the exhausted particulate matter to be separated is detected based on the operating state detecting means for detecting, the amount of exhaust particulate matter detected by the deposit amount detecting means, and the operating state detected by the operating state detecting means. When the separation occurrence condition detecting means and the separation condition of the exhaust particulate matter detected by the separation occurrence condition detecting means are equal to or more than a predetermined frequency, the exhaust particulate matter collected in the filter is burned to regenerate the filter. Regeneration means, exhaust pressure control means provided in an exhaust passage upstream of the filter to prevent exhaust gas from flowing into the filter and increase exhaust pressure upstream of the filter; Before and after the regeneration by the means, the combustion amount of the exhaust particulate matter is obtained based on the deposition amount of the exhaust particulate matter detected by the deposition amount detecting means, and when the combustion amount is less than a predetermined value, it is determined that the regeneration condition of the filter is defective. Means and the regeneration state determining means, when the regeneration of the filter is determined to be defective, the exhaust pressure control means repeatedly performs the operation and release of the exhaust gas inflow prevention to control the exhaust pressure upstream of the filter, and the exhaust particulates deposited on the filter. An exhaust gas purification device for a diesel engine, characterized in that the exhaust gas particulate removal device gradually removes the exhaust gas by the exhaust pressure.