JP2011099378A - Dpf regeneration control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unnecessary regeneration operation in a regeneration process of a DPF. <P>SOLUTION: This device includes a PM accumulation quantity operation means 21 operating a PM accumulation quantity to the DPF 9 from an operation state of an engine 1, a differential pressure detection means 22 detecting the differential pressure between the upstream side and the downstream side of the DPF 9, and a regeneration request means 23 determining the degree of necessity of regeneration based on the PM accumulation quantity operated by the PM accumulation quantity operation means 21 and differential pressure detected by the differential pressure detection means 22 and requesting regeneration based on the determination result. A regeneration necessary region where regeneration is necessary is set with regard to the PM accumulation quantity, and a regeneration unnecessary region where regeneration is not necessary is set in regard to differential pressure. A regeneration request means 23 requests regeneration after a stand-by process in which a regeneration request is reserved if PM accumulation quantity is within the regeneration necessary region but differential pressure is within the regeneration unnecessary region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a DPF regeneration control device that performs regeneration of a filter (DPF) that collects and removes particulate matter in exhaust gas from a diesel engine at an optimal interval.

  Vehicles equipped with diesel engines (also called simply engines) usually contain particulate matter such as soot in the exhaust gas (hereinafter abbreviated as PM), which is directly released into the atmosphere. In order to prevent this, a filter called a particulate filter (Diesel Particulate Filter, hereinafter abbreviated as DPF) that collects PM is provided in the exhaust passage of the engine (see, for example, Patent Document 1). .

DPF has a limit on the amount of PM collected (PM accumulation amount), and the exhaust pressure of the engine increases as the PM accumulation amount increases, resulting in deterioration of fuel consumption. If the PM accumulation amount exceeds the reference value, Then, DPF regeneration processing for removing PM accumulated in the DPF is performed. As a method for regenerating DPF, an oxidation catalyst is disposed upstream of the DPF, NO ₂ is generated from NO by the oxidation catalyst, and PM is combusted by using the redox reaction of the generated NO _2. There are known methods of continuous regeneration and forced regeneration in which fuel is supplied into the exhaust pipe, this fuel is combusted by an oxidation catalyst disposed upstream of the DPF, and PM is forcibly combusted by the combustion heat. .

There are two types of forced regeneration, called automatic regeneration and manual regeneration. Automatic regeneration is a method of supplying fuel and forcibly burning and removing PM during vehicle operation. Manual regeneration is a method of supplying fuel while the vehicle operation is stopped and the vehicle is stopped. In this method, PM is forcibly burned and removed.
Since automatic regeneration burns and removes PM during normal operation, forced operation is performed in various engine operating states. On the other hand, the manual regeneration is performed under a stable condition in which the vehicle is stopped. For the driver, automatic regeneration that does not require interruption of operation is suitable, but manual regeneration is suitable for burning PM stably and reliably. In particular, in the state where PM is excessively accumulated, in automatic regeneration in which stable combustion is difficult, the excessively accumulated PM may burn at once and cause damage to the filter. Therefore, manual regeneration that enables stable combustion is possible. Is preferred. However, when the excessive accumulation further proceeds, even manual regeneration cannot secure the stability of PM combustion, and it becomes difficult to perform regeneration.

  As a technique for estimating the amount of PM accumulated in the DPF, as described in Patent Document 2, information on the engine speed and engine load is obtained as engine operating state information, and the engine speed and The PM emission amount (mg / sec) per unit time according to the engine load is obtained by, for example, a map prepared in advance, and accumulated in the DPF from the cumulative engine operating time since the DPF is new or after regeneration. A technique for estimating the amount of accumulated PM (amount of DPF accumulated for engine operation) is known. Further, as described in Patent Document 3, the pressure on the upstream side of the DPF is detected by a pressure sensor, the pressure on the downstream side is estimated, and PM is calculated from the differential pressure between the pressure on the upstream side and the pressure on the downstream side. Estimate PM deposition amount (DPF deposition amount corresponding to differential pressure) from pressure difference sensor (DPF pressure difference before and after DPF) by detecting both upstream and downstream pressure of DPF with pressure sensor. The technology to do is known.

Japanese Patent No. 3925472 JP 2007-270695 A JP 2008-144709 A

  By the way, paying attention to the amount of accumulated PM in the DPF, as shown in FIG. 8, when the engine is operated for normal driving (also simply referred to as normal operation), the amount of accumulated PM gradually increases. When the forced regeneration threshold is reached, the amount of PM deposition gradually decreases due to the start of forced regeneration. Such a change in the amount of accumulated PM in the DPF is repeated alternately. The regeneration operation of the DPF is performed when the PM accumulation amount reaches the forced regeneration threshold, but the PM accumulation amount is the PM of each of the DPF accumulation amount corresponding to the engine operation and the DPF accumulation amount corresponding to the differential pressure as described above. The accumulation amount is estimated, and when any PM accumulation amount reaches the forced regeneration threshold first, the forced regeneration is performed at this point, and thereby the regeneration interval is determined.

  In FIG. 8, the solid line graph shows the estimated PM deposition amount that has reached the forced regeneration threshold first among the PM deposition amounts estimated by the above two techniques (hereinafter referred to as the estimated PM deposition amount), and the broken line graph is the actual one. Shows the amount of PM deposited in the DPF. The estimated PM accumulation amount is an estimated value to the last, and there are many cases where all the factors that determine the actual PM accumulation amount cannot be considered, and a deviation as shown in FIG. 8 occurs.

As shown in FIG. 8, the first cycle (combined normal operation and regeneration operation) and the second cycle are not so large although there is a difference between the estimated PM accumulation amount and the actual PM accumulation amount. When the estimated PM accumulation amount reaches the forced regeneration threshold, the operation for regenerating the DPF is started.
However, in the third cycle, the difference between the estimated PM deposition amount and the actual PM deposition amount is larger than the previous two times, and the actual PM deposition amount has reached the forced regeneration threshold value, although it is practically almost PM. Is not deposited. This is a phenomenon that can occur due to factors that cannot be taken into account when determining the estimated amount of PM deposition, and is often caused by an oxidation (continuous regeneration) state by NO ₂ in particular.

  Since it is very difficult to accurately detect the amount of PM burned by continuous regeneration, the estimated PM accumulation amount may deviate significantly from the actual PM accumulation amount as in the third cycle. If the estimated PM accumulation amount reaches the forced regeneration threshold, the regeneration of the DPF is performed. However, this regeneration operation is obviously unnecessary, and performing unnecessary regeneration operation leads to deterioration of fuel consumption, that is, useless energy consumption, unnecessary exhaust gas discharge, and the like. In addition, when performing manual regeneration, the vehicle must be stopped, which is a heavy burden on the driver.

  The present invention has been devised in view of such problems, and an object of the present invention is to provide a DPF regeneration control apparatus that can avoid unnecessary regeneration operation in the regeneration process of the DPF.

  In order to solve the above problems, a DPF regeneration control device of the present invention is a control for removing and regenerating the PM of a filter (DPF) that collects particulate matter (PM) contained in exhaust gas from a diesel engine. A DPF regeneration control apparatus that performs PM accumulation amount calculation means for calculating a PM accumulation amount on the DPF from an operating state of the diesel engine, and a differential pressure between the upstream side and the downstream side of the DPF directly or indirectly Determining the necessary degree of the regeneration based on the differential pressure detecting means for detecting automatically, the PM deposit amount calculated by the PM deposit amount calculating means, and the differential pressure detected by the differential pressure detecting means, A regeneration requesting means for performing a regeneration request based on the determination result, a regeneration necessary region where the regeneration is necessary is set for the PM deposition amount, and the regeneration is performed for the differential pressure. An unnecessary regeneration unnecessary area is set, and the regeneration requesting unit has undergone a standby process for holding the regeneration request if the PM accumulation amount is in the regeneration necessary area but the differential pressure is in the regeneration unnecessary area. It is characterized by requiring playback above.

  Further, the present invention relates to the PM deposition amount, wherein the regeneration necessary region includes a manual regeneration necessary region (level 3) in which the PM deposition amount is a large level and an automatic regeneration necessary region (in which the PM deposition amount is a medium level). In addition to these, a regeneration unnecessary area (level 1) in which the regeneration is unnecessary and the amount of PM deposition is small is set, and the regeneration requesting means If the amount is in the manual regeneration necessary region, manual regeneration is requested regardless of the differential pressure, and if the PM accumulation amount is in the automatic regeneration necessary region, unless the differential pressure is in the regeneration unnecessary region, It is preferable to request regeneration immediately, and when the differential pressure is in the regeneration unnecessary area, the regeneration is requested after the standby process.

  Further, regarding the differential pressure, in addition to the regeneration unnecessary region (level 1) where the differential pressure is at a low level, a manual regeneration necessary region where the differential pressure is at a high level and manual regeneration is required as the regeneration ( Level 3) and a dead zone area (no level) in which the differential pressure is between the regeneration unnecessary area and the manual regeneration necessary area and the determination of the necessity of regeneration is reserved, The regeneration requesting unit requests manual regeneration regardless of the PM deposition amount if the differential pressure is in the manual regeneration necessary region, and if the differential pressure is in the dead zone region, the PM deposition amount is It is preferable that manual regeneration is requested if it is in the regeneration necessary region, and automatic regeneration is requested if the PM accumulation amount is in the automatic regeneration necessary region.

  Further, regarding the PM accumulation amount, an unreproducible region (level 4) in which the PM accumulation amount is an excessive level larger than the large level is further set, and the differential pressure is greater than the high level with respect to the differential pressure. A non-renewable region (level 4), which is a higher excessive level, is further set, and the regeneration request means outputs the output of the diesel engine if either the PM accumulation amount or the differential pressure is a non-renewable region. It is preferable to request restrictions.

Further, the standby process includes a hold process for holding a regeneration request and a determination as to whether or not the differential pressure is in the regeneration unnecessary area for a predetermined standby time set in advance, and the difference between the hold process and the hold process. A process that includes a determination process for determining whether or not the pressure is in the regeneration unnecessary region up to a predetermined number of times, and the differential pressure is generated during the standby process. When it is determined that it has departed from the unnecessary area, the standby process is terminated and processing according to the differential pressure area is performed, and the processing cycle is performed without determining that the differential pressure has deviated from the regeneration unnecessary area. When the predetermined number of times is reached, it is preferable that the reproduction requesting unit issues a reproduction request.

  Further, it is preferable that the PM accumulation amount calculation means stops the calculation of the PM accumulation amount during the standby process.

  According to the DPF regeneration control device of the present invention, the regeneration operation in a state where PM is not actually accumulated in the DPF is suspended, so that unnecessary regeneration operation is not performed by reducing the regeneration process of the DPF. Energy consumption, unnecessary exhaust gas emission, fuel consumption deterioration, and the like can be suppressed. In addition, oil dilution that occurs when fuel supply to the exhaust pipe for forced regeneration is provided by fuel injection (post-injection) into the engine combustion chamber can be suppressed, and the oil change interval is extended. be able to.

  In addition, when the area is divided according to the PM accumulation amount and the regeneration necessity degree is determined for each area, if it is determined that the manual regeneration is necessary, the PM is removed, and the PM accumulation amount is in the automatic regeneration necessary area. Since the PM accumulation level is detected from the differential pressure without performing regeneration immediately, and a request corresponding to the level is issued, regeneration is performed if necessary, and regeneration is suspended if not necessary. Unnecessary regeneration operation can be suppressed.

Also, regarding the differential pressure, if the area is classified according to the PM deposition level and the degree of regeneration required is determined for each area, even if the PM deposition level due to the differential pressure is in the dead zone area, appropriate regeneration is performed according to the PM deposition amount. can do.
In addition, by setting the non-renewable area to either the PM accumulation amount or the differential pressure, and requesting the engine output limit when either the PM accumulation amount or the differential pressure is the non-regenerative area, The deposition preventing function can be further improved.

  Further, the regeneration standby process is a processing cycle comprising a holding process for holding for a predetermined time set in advance and a determination process for determining whether or not the differential pressure is in the regeneration unnecessary area. In the case where the number of times is implemented as a limit, the suspension of regeneration is not performed for a long period of time, and it is determined whether regeneration is necessary depending on the PM accumulation level even during the regeneration standby processing. Therefore, when reproduction is necessary, reproduction can be performed promptly.

It is a mimetic diagram showing composition of an internal-combustion engine of vehicles carrying an exhaust gas purification device to which a DPF regeneration control device concerning one embodiment of the present invention is applied. It is a flowchart shown about the regeneration status determination process by DPF regeneration control concerning one Embodiment of this invention. It is a subroutine of the reproduction standby process in the flowchart of FIG. It is the figure which showed the necessity degree of DPF regeneration used for DPF regeneration control concerning one embodiment of the present invention based on the differential pressure of the upstream and downstream of the DPF and the exhaust flow rate according to the level. It is a flowchart which determines the level of DPF regeneration by the differential pressure used for DPF regeneration control concerning one Embodiment of this invention. It is the figure which showed the necessity degree of the DPF reproduction | regeneration obtained by PM deposition amount used for DPF regeneration control concerning one Embodiment of this invention according to the level. It is a flowchart shown about PM deposition amount calculation processing used for DPF regeneration control concerning one Embodiment of this invention. It is the figure which showed PM deposition amount for demonstrating the conventional subject.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A DPF regeneration control apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. 1 shows a configuration of an internal combustion engine of a vehicle equipped with an exhaust purification apparatus to which the DPF regeneration control apparatus is applied. FIG. 2 is a flowchart showing regeneration status determination processing by DPF regeneration control, FIG. 3 is a regeneration standby processing subroutine in the flowchart of FIG. 2, and FIG. 4 is obtained based on the differential pressure upstream and downstream of the DPF and the exhaust flow rate. FIG. 5 is a flowchart for determining the level of DPF regeneration based on the differential pressure, FIG. 6 is a diagram illustrating the degree of necessity for DPF regeneration obtained by the amount of PM deposition, and FIG. 7 is a flowchart showing PM accumulation amount calculation processing.

  As shown in FIG. 1, a diesel engine (also simply referred to as an engine) 1 according to the present embodiment includes a combustion chamber 3 formed in each cylinder 2, an intake passage 4 that feeds intake air into the combustion chamber 3, and a combustion And an exhaust passage 5 through which exhaust gas generated by combustion in the chamber 3 is discharged. The air sucked into the intake passage 4 is mixed with the fuel injected by the fuel injection valve 6 provided in the combustion chamber 3 to become an air-fuel mixture and burns in the combustion chamber 3. The intake passage 4 is provided with an air flow meter 7 for detecting the amount of air taken into the combustion chamber 3.

  The exhaust passage 5 collects an oxidation catalytic converter 8 that oxidizes and purifies harmful HC (hydrocarbon) and CO (carbon monoxide) contained in the exhaust, and PM (Particulate Matter). A DPF (Diesel Particulate Filter) 9 to be processed is sequentially arranged from the upstream side of the exhaust gas flow, and exhaust gas generated by the combustion in the combustion chamber 3 is fed into it. In the present embodiment, the DPF 9 also carries an oxidation catalyst that oxidizes HC and CO in the exhaust.

The fuel injection valve 6 is used to supply fuel to the oxidation catalytic converter 8 upstream of the DPF 9 by post injection or the like that injects fuel at a timing at which combustion does not occur in the combustion chamber 3 (mainly during the exhaust process). Is oxidized by the oxidation catalytic converter 8 to increase the exhaust temperature, and the DPF 9 is regenerated by burning and removing the PM of the DPF 9.
Further, a temperature sensor 10 and a pressure sensor 11 are provided in this order between the oxidation catalytic converter 8 and the DPF 9 in the exhaust passage 5. The temperature sensor 10 is for detecting the temperature of the exhaust gas flowing through the exhaust passage 5, and the pressure sensor 11 is for detecting the pressure upstream of the DPF 9.

  In this embodiment, since the downstream side of the DPF 9 is considered to be a constant pressure that is higher than the atmospheric pressure by a certain pressure loss, only the pressure upstream of the DPF 9 is detected without detecting the pressure downstream of the DPF 9. Thus, the pressure upstream of the DPF 9 is subtracted by the above constant pressure value and used as the pressure difference between the upstream and downstream of the DPF 9 (differential pressure across the DPF). Of course, a pressure sensor 11 may be provided to detect both upstream and downstream pressures of the DPF 9, and the pressure difference between them may be obtained directly.

Further, a muffler 12 for reducing noise caused by exhaust is provided downstream of the DPF 9, and the tip thereof directly communicates with the atmosphere.
Various controls of the diesel engine 1 are performed by an engine control device (hereinafter referred to as an engine ECU) 20. The engine ECU 20 includes a CPU that executes various arithmetic processes related to engine control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU calculation results, and signals externally. Are provided with an input / output port and the like.

  Then, the engine ECU 20 detects a functional element as the PM accumulation amount calculating means 21 that calculates the amount of PM accumulated in the DPF 9 (PM accumulation amount) based on the operating state of the engine 1 and the differential pressure across the DPF 9. It has a functional element as the differential pressure detecting means 22 and a functional element as the regeneration requesting means 23 for determining the degree of regeneration necessary for the DPF 9 and executing the regeneration request.

  Various known techniques can be applied to the PM accumulation amount calculation means 21. For example, information on the engine speed Ne and the engine load Le such as the fuel injection amount is obtained as the operating state information of the engine 1, and the PM emission amount (mg) per unit time according to the engine speed Ne and the engine load Le is obtained. / Sec) is obtained from, for example, a map prepared in advance, and a technique for estimating the PM accumulation amount accumulated in the DPF 9 from the accumulated engine operation time from when the DPF 9 is new or after regeneration is known. It is not limited to this.

  The differential pressure detection means 22 sets a pressure value higher than the atmospheric pressure by a certain pressure loss as a pressure value on the downstream side of the DPF 9 and subtracts this pressure value from the pressure on the upstream side of the DPF 9 detected by the pressure sensor 11. The pressure difference between upstream and downstream (DPF front-rear differential pressure) ΔP. However, the pressure on the downstream side of the DPF 9 may be detected by providing the pressure sensor 11 and the pressure difference may be obtained directly.

Then, the information of the PM accumulation amount PM _A estimated by the PM accumulation amount calculating means 21 and the differential pressure ΔP detected by the differential pressure detecting means 22 is sent to the regeneration request means 23 which is one of the functional elements of the engine ECU 20.
The regeneration request unit 23 determines whether or not the regeneration of the DPF 9 is necessary based on the information of the PM accumulation amount PM _A and the differential pressure ΔP sent from the PM accumulation amount calculation unit 21 and the differential pressure detection unit 22 (regenerative necessity level). Determine. This necessary degree determination process will be described later.

Furthermore, if the regeneration request unit 23 determines that the DPF 9 needs to be regenerated in the determination result, the regeneration request unit 23 issues a regeneration request to a replay execution unit (not shown), and the regeneration of the DPF 9 is performed accordingly.
The DPF regeneration control apparatus includes a PM accumulation amount estimating means 21, a differential pressure detecting means 22, and a regeneration requesting means 23, all of which are provided as functional elements of the engine ECU 20.

Here, the necessary degree of reproduction will be described with reference to FIGS.
FIG. 4 is a view showing the level of PM deposition amount (hereinafter referred to as PM deposition level) determined based on the differential pressure upstream and downstream of the DPF 9 and the exhaust gas flow rate, and is used by the differential pressure detection means 22. As shown in FIG. 4, the PM deposition level is divided into the following four stages.
Level 4 is a non-renewable area (excessive level) in which a very large amount of PM is accumulated so that the regeneration of the DPF 9 cannot be performed. If this area is detected by the differential pressure detection means 22, the regeneration is performed. The request means 23 determines that regeneration is impossible, and takes fail-safe measures such as displaying an engine warning light and limiting engine output.

Level 3 is a manual regeneration necessary region (high level) in which a large amount of PM is accumulated in the DPF 9 although not as much as level 4, and when this region is detected by the differential pressure detection means 22, the regeneration request means 23 Therefore, it is determined that manual regeneration is necessary, and a regeneration request is issued to perform manual regeneration.
Level 1 is a regeneration unnecessary area (low level) in which almost no PM is deposited on the DPF 9, and when this area is detected by the differential pressure detection means 22, a standby request for holding the temporary regeneration by the regeneration request means 23. Is made.

Here, a region between level 1 and level 3 is a dead zone region (medium level) where PM is accumulated in the DPF 9 but is difficult to determine whether regeneration is necessary. When this area is detected by the means 22, it is difficult to determine the necessary degree of reproduction based only on the detection result, and in this case, the necessary degree of reproduction is not determined.
FIG. 6 is a diagram showing the PM accumulation level determined based on the PM accumulation amount PM _A obtained by the PM accumulation amount calculating means 21. The PM accumulation level shown in FIG. 6 is also divided into four stages. Level 4, level 3 and level 1 are the same as those in FIG. It is an unnecessary area (small level). Level 2 shown in FIG. 6 is an automatic regeneration necessary area (medium level) in which PM that can be processed by automatic regeneration is accumulated in the DPF 9.

The reason why the PM accumulation level is obtained by the PM accumulation amount calculating means 21 and the differential pressure detecting means 22 is that the respective strengths in the detection of the PM accumulation level are different.
Since the differential pressure detection means 22 detects the PM accumulation level from the differential pressure with respect to the exhaust flow rate, it can hardly detect the level when the exhaust flow rate is small. In addition, when the exhaust gas flow rate is high to some extent, and a large amount of PM is accumulated as in level 3 and level 4, the level can be detected reliably, but the PM deposition is about whether or not automatic regeneration is necessary. The amount is hard to detect. Therefore, there is a dead zone region as described above. However, if the exhaust flow rate is large to some extent and there is almost no differential pressure, PM is not deposited on the DPF 9, so that it is possible to detect the regeneration unnecessary region as described above.

On the other hand, the PM accumulation amount calculating means 21 detects the amount of PM emission per unit from the operation state of the time the engine 1, calculates the PM accumulation amount PM _A by accumulating it. As for the continuous reproduction performed during normal driving in this prediction calculation, the current situation is that the accuracy does not easily increase due to the complexity of the factors affecting and the difficulty of detection. However, the PM accumulation amount calculation means 21 is characterized in that the PM accumulation amount prediction accuracy in a region where continuous regeneration does not occur is good and that the PM accumulation level can be detected regardless of the exhaust gas flow rate.

As Here, characteristic control, determining reproduction request means 23, if the PM accumulation amount PM _A by PM accumulation amount calculation means 21 is calculated to autoplay necessary area (level 2), requires immediate AutoPlay Instead, it is confirmed how much the PM deposition level obtained by the differential pressure detection means 22 is, in order to confirm whether PM is deposited on the DPF 9 to the extent that regeneration is necessary. When the PM deposition level obtained by the differential pressure detection means 22 is the dead zone region of FIG. 4 described above, it is assumed that PM is deposited to the extent that automatic regeneration is necessary, and automatic regeneration is necessary. Determined.

  On the other hand, when the PM accumulation level obtained by the differential pressure detection means 22 is the regeneration unnecessary area (level 1) in FIG. 4 described above, the PM accumulation amount calculating means 21 performs the PM automatic regeneration necessary area (level 2). Although it has been calculated that it has accumulated to a certain extent, in reality, almost no PM has accumulated, so it is determined that regeneration is required after the regeneration requesting means 23 holds the regeneration standby process for deferring regeneration of the DPF 9. The

The reproduction standby process is a process for executing a processing cycle including a hold process and a determination process. The hold process holds the regeneration request and the determination as to whether or not the differential pressure detected by the differential pressure detection means 22 is in the regeneration unnecessary area for a predetermined standby time (for example, 30 minutes) set in advance, The calculation of the PM accumulation amount PM _A by the PM accumulation amount calculating means 21 is stopped. The determination process determines whether or not the differential pressure is in the regeneration unnecessary region when the predetermined standby time holding process is completed. A processing cycle composed of these two processes is executed up to a predetermined number of times (for example, three times) as a limit. However, the waiting time and the predetermined number of times described above are not limited to this.

  The above standby time is, for example, one tenth of the value based on the regeneration interval averaged from the driving pattern of the vehicle so far, for example, average speed and load frequency (how to step on the accelerator). To be determined. In the above example, the averaged playback interval is 5 hours (300 minutes), and since 1/10 is 30 minutes, the predetermined standby time set in advance is 30 minutes.

  In this regeneration standby process, when it is determined that the differential pressure has deviated from the regeneration unnecessary area during the processing cycle, the regeneration standby process is terminated and PM deposition based on the differential pressure detected by the differential pressure detection means 22 is performed. It is determined that reproduction according to the level is necessary. On the other hand, even if the processing cycle is performed a predetermined number of times that is set in advance, it may be determined that the differential pressure is still in the regeneration unnecessary area. Even in this case, regeneration is required by the regeneration request means 23. It is determined that This is because, if there is a case where the differential pressure is not detected by the differential pressure detection means 22 for some reason, the DPF 9 breaks down or the output of the engine 1 is limited. The waiting period is determined by the number of cycles.

  Since the DPF regeneration control device according to one embodiment of the present invention is configured as described above, the regeneration control of the DPF according to the present embodiment is performed according to the flowcharts shown in FIGS. 2, 3, 5, and 7. Is done.

FIG. 2 is a flowchart showing a regeneration status determination process used for DPF regeneration control. As shown in FIG. 2, first, the PM deposition level PM _C based on the differential pressure upstream and downstream of the DPF 9 detected by the differential pressure detection means 22 is acquired (step S1). As shown in the flowchart of FIG. 5, the PM deposition level PM _C is acquired by first detecting the exhaust flow rate by the air flow meter 7 (step S50), and setting a pressure value higher than the atmospheric pressure by a certain pressure loss downstream of the DPF 9. The pressure value on the downstream side is subtracted from the pressure on the upstream side of the DPF 9 detected by the pressure sensor 11, and the pressure difference between the upstream and downstream sides of the DPF 9 is detected by the differential pressure detection means 22 (step S51). ). Then, based on these information, detects the PM deposition level PM _C shown in FIG. 4 by the differential pressure detecting means 22 (step S52), and returns to step S50.

Next, as shown in FIG. 2, it is determined whether or not the acquired PM _C is level 4 which is a non-reproducible region (step S2). If it is level 4, the DPF 9 cannot be regenerated, so the engine Fail-safe measures such as turning on a warning light and limiting engine output are performed (step S7), and the process ends. On the other hand, if PM _C is not level 4, to determine the level 3 or not is manual regeneration necessary area for (step S3), and if the level 3 is required manual regeneration of DPF 9, carried out manual regeneration (Step S9), the process returns to Step S1. On the other hand, if PM _C is not level 3, it is determined whether the reproduction waiting process is being executed (step S4).

When the regeneration standby process is not being executed, the PM accumulation amount PM _A obtained by the PM accumulation amount calculating means 21 is acquired (step S5), and the level of PM _A is determined.
As shown in the flowchart of FIG. 7, the acquisition of the PM accumulation amount PM _A when the regeneration standby process is not being executed is first performed as engine operating state information such as engine speed Ne, fuel injection amount, etc. Is detected (step S60). Next, it is determined whether or not regeneration of the DPF 9 is being performed (step S61). If regeneration is being performed, the PM has been burned and removed, so the value corresponding to the engine operating state is subtracted. The deposition amount is calculated (step S62). On the other hand, when the regeneration of the DPF 9 is not being performed, the PM accumulation amount is calculated by normal accumulation, that is, the value corresponding to the engine operation state is calculated (step S63), and the process returns to step S60. The PM accumulation amount PM _A detected in steps S62 and S63 is read in step S5 of FIG.

Next, as shown in FIG. 2, it is determined whether or not the acquired PM _A is level 4 which is a non-reproducible area (step S6). If it is level 4, the DPF 9 cannot be regenerated, so the engine Fail-safe measures such as turning on a warning light and limiting engine output are performed (step S7), and the process ends. On the other hand, if PM _A is not level 4, it is determined whether it is level 3 which is a manual regeneration necessary area (step S8). If it is level 3, manual regeneration of DPF 9 is necessary, so manual regeneration is performed. (Step S9), the process returns to Step S1.

In step S8, if PM _A is not level 3, it is determined whether or not it is level 2 which is an automatic regeneration required area (step S10). If PM _A is not level 2, it is level 1 which is an unnecessary regeneration area. Therefore, neither the regeneration of the DPF 9 nor the regeneration standby process is performed, and the process returns to step S1. On the other hand, if PM _A is level 2, the reproduction standby process shown in FIG. 3 is started (step S20). In step S4, when the reproduction standby process is being executed, the process directly proceeds to the reproduction standby process.

FIG. 3 is a subroutine constituting the reproduction standby process in the flowchart of FIG. In the reproduction standby process, as shown in FIG. 3, it is first determined whether or not a timer (not shown) is stopped (step S21). When you start playback standby processing, the timer because it is stopped, then, PM deposition level PM _C obtained in step S1 it is determined whether the level 1 is a reproduction unnecessary area (step S22), and the level 1 If it is, the number of carried out standby processing cycle (hereinafter, also referred to as a standby process count) BC is, determines a predetermined number of times which is the limit of the processing cycle execution count (for example, 3 times) whether B _th or more ( Step S30). If BC is less than B _th is a timer after 0 reset (step S31), starts a timer (step S32), stops the operation of the PM accumulation amount PM _A by PM deposition amount calculating unit 21 (step S33), the process returns to step S1.

In the next control cycle, PM _C obtained in step S1 is if neither Level 3 even level 4, to be judged as playback standby processing being executed in step S4, the procedure returns to the playback standby processing (step S20).
In step S21, it is determined again whether the timer is stopped. However, since the timer is started in step S32 of the previous control cycle, it is determined that the timer is not stopped (step S21), and the timer is integrated. (Step S40). Then, it is determined whether or not the timer integrated value is equal to or longer than a predetermined standby time (for example, 30 minutes) T _th set in advance (step S41). When the timer integrated value is smaller than _Tth , the process returns to step S1 again. On the other hand, if the timer integrated value is equal to or greater than T _th , the timer is stopped (step S42), and the standby process count BC is set to a value obtained by adding 1 to the previous standby process count (step S43). Since the standby process count BC is initially 0, BC = 1 in this case. Then, the calculation of the PM accumulation amount PM _A by the PM accumulation amount calculating means 21 is resumed (step S44), and the process returns to step S1.

In the next control cycle, PM _C obtained in step S1 is if neither Level 3 even level 4, to be judged as playback standby processing being executed in step S4, the procedure returns to the playback standby processing (step S20).
While again the timer in step S21, it is determined whether stopped or because it stops the timer in step S42 in the previous control cycle, a PM deposition level PM _C level 1 obtained by means 22 and differential pressure detection again It is determined whether or not (step S22). When PM _C is still level 1 determines whether or not the standby processing count BC is B _th or more in the step S30 again. On the other hand, if it is determined in step S22 that PM _C is not level 1, it is determined that regeneration of DPF 9 is necessary, a regeneration request in accordance with the level of PM _C is issued (step S23), and standby processing count BC Is reset to 0 (step S24), the reproduction standby process is stopped (step S25), and the process returns to step S1.

If BC is greater than or equal to B _th in step S30, the above steps S23 to S25 are similarly performed. On the other hand, if BC is smaller than B _th in step S30, the timer is reset to 0 again (step S31), the timer is started (step S32), and the PM accumulation amount PM _A by the PM accumulation amount calculating means 21 is set. The calculation is stopped (step S33), and the process returns to step S1.

Acquiring the flowchart of FIGS. 2 and 3 described above, the flowchart of FIG. 5 and FIG. 7 is proceeded in parallel, the PM _C detected in step S52 in FIG. 5 as described above in step S1 of FIG. 2 Then, PM _A detected in steps S62 and S63 in FIG. 7 is acquired in step S5 in FIG.

As described above, according to the DPF regeneration control device, when the PM accumulation amount PM _A reaches the automatic regeneration necessary region, the regeneration is not performed immediately, the PM deposition level PM _C due to the differential pressure is confirmed, and the PM is still When NO is accumulated, regeneration standby processing for holding the regeneration operation of the DPF 9 is performed, so that deterioration of fuel consumption, that is, useless energy consumption, unnecessary exhaust gas emission, and the like can be suppressed. In addition, oil dilution that occurs when fuel supply to the exhaust pipe for forced regeneration is provided by fuel injection (post-injection) into the engine combustion chamber can be suppressed, and the oil change interval is extended. be able to.

Further, since it is checked whether PM is deposited on the DPF 9 based on the PM deposition amount PM _A and the PM deposition level PM _C based on the differential pressure, the PM deposition can be detected more reliably, and the PM deposition amount and the PM deposition level can be detected. Appropriate reproduction according to the can be performed.
Further, by setting the non-renewable region (level 4) to either the PM accumulation amount or the differential pressure, and requesting the engine output limit when either the PM accumulation amount or the differential pressure is the non-renewable region, The conventional over-deposition prevention function can be further improved.

  Further, the regeneration standby process is a processing cycle comprising a holding process for holding for a predetermined time set in advance and a determination process for determining whether or not the differential pressure is in the regeneration unnecessary area. In the case where the number of times is implemented as a limit, the suspension of regeneration is not performed for a long period of time, and it is determined whether regeneration is necessary depending on the PM accumulation level even during the regeneration standby processing. Therefore, when reproduction is necessary, reproduction can be performed promptly.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, a period for holding the reproduction in the above embodiments has been determined using the two limits B _th upper T _th processing cycle the number of times of execution of preset timer integrated value, the limit B _th processing cycle execution count The upper limit T _th of the timer integrated value may be set longer by that amount.

1 Diesel engine (engine)
2 cylinder 3 combustion chamber 4 intake passage 5 exhaust passage 6 fuel injection valve 7 air flow meter 8 oxidation catalytic converter 9 diesel particulate filter (DPF)
DESCRIPTION OF SYMBOLS 10 Temperature sensor 11 Pressure sensor 12 Muffler 20 Engine control apparatus (engine ECU)
21 PM accumulation amount calculation means 22 Differential pressure detection means 23 Regeneration request means

Claims (6)

A DPF regeneration control device that performs control to remove and regenerate the PM of a filter (DPF) that collects particulate matter (PM) contained in exhaust gas from a diesel engine,
PM accumulation amount calculating means for calculating the PM accumulation amount on the DPF from the operating state of the diesel engine;
Differential pressure detection means for directly or indirectly detecting the differential pressure between the upstream side and the downstream side of the DPF;
Based on the PM accumulation amount calculated by the PM accumulation amount calculating means and the differential pressure detected by the differential pressure detecting means, the degree of necessity of the regeneration is determined, and a regeneration request is made based on the determination result. And a reproduction request means for
Regarding the PM deposition amount, a regeneration necessary area where the regeneration is necessary is set,
Regarding the differential pressure, a regeneration unnecessary area where the regeneration is unnecessary is set,
The regeneration requesting unit requests regeneration after a standby process for holding the regeneration request if the PM accumulation amount is in the regeneration necessary region but the differential pressure is in the regeneration unnecessary region. A DPF regeneration control device. Regarding the PM deposition amount, the regeneration necessary area is divided into a manual regeneration necessary area where the PM deposition amount is a large level and an automatic regeneration necessary area where the PM deposition amount is a medium level. , The regeneration unnecessary area where the regeneration is unnecessary, where the PM deposition amount is a small level, is set,
The reproduction request means includes
If the PM accumulation amount is in the manual regeneration necessary region, manual regeneration is requested regardless of the differential pressure,
If the PM accumulation amount is in the automatic regeneration required area, automatic regeneration is immediately requested unless the differential pressure is in the regeneration unnecessary area, and if the differential pressure is in the regeneration unnecessary area, the standby process is performed. 2. The DPF regeneration control apparatus according to claim 1, wherein automatic regeneration is requested after passing through. Regarding the differential pressure, in addition to the regeneration unnecessary region where the differential pressure is low, the manual regeneration necessary region where the differential pressure is high and manual regeneration is necessary as the regeneration, and the differential pressure is A dead zone area that is a medium level between the regeneration unnecessary area and the manual regeneration necessary area and that reserves the determination of the necessity of reproduction is set,
The reproduction request means includes
If the differential pressure is in the manual regeneration required region, manual regeneration is requested regardless of the PM accumulation amount,
When the differential pressure is in the dead zone, manual regeneration is requested if the PM accumulation amount is in the manual regeneration necessary region, and automatic regeneration is requested if the PM deposition amount is in the automatic regeneration necessary region. The DPF regeneration control device according to claim 2, characterized in that: Regarding the PM deposition amount, a non-renewable region in which the PM deposition amount is an excessive level larger than the large level is further set, and regarding the differential pressure, the differential pressure is an excessive level higher than the high level. A non-reproducible area is further set,
4. The DPF regeneration control apparatus according to claim 3, wherein the regeneration requesting unit requests the diesel engine output restriction if either the PM accumulation amount or the differential pressure is in a non-recoverable region. The standby process includes a hold process for holding a regeneration request and a determination as to whether or not the differential pressure is in the regeneration unnecessary area for a predetermined standby time set in advance, and the differential pressure is obtained through the hold process. A process for carrying out a processing cycle consisting of a determination process for determining whether or not the reproduction unnecessary area is present up to a predetermined number of times,
During the standby process, if it is determined that the differential pressure has deviated from the regeneration unnecessary area, the standby process is terminated and regeneration is performed according to the differential pressure area, and the differential pressure is removed from the regeneration unnecessary area. 5. The DPF regeneration control according to claim 1, wherein the regeneration requesting unit performs the regeneration request when the processing cycle reaches the predetermined number of times without being determined to have been performed. apparatus. 6. The DPF regeneration control apparatus according to claim 1, wherein the PM accumulation amount calculation unit stops the calculation of the PM accumulation amount during the standby process. 7.

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