JP3951619B2 - Continuous regeneration type diesel particulate filter device and regeneration control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous regeneration type diesel particulate filter device that collects particulate matter of a diesel engine and purifies exhaust gas, and a regeneration control method thereof.
[0002]
[Prior art]
The amount of particulate matter discharged from diesel engines (PM: particulates: hereinafter referred to as PM) is being regulated more and more with NOx, CO, HC, etc., and this particulate matter is filtered into a diesel particulate filter (DPF). : Diesel Particulate Filter (hereinafter referred to as DPF), and a technique for reducing the amount of PM discharged to the outside has been developed.
[0003]
The DPF for collecting PM includes a ceramic monolith honeycomb wall flow type filter, a fiber type filter type filter made of ceramic or metal, and an exhaust gas purification apparatus using these DPFs. Like other exhaust gas purification devices, is installed in the middle of the exhaust pipe of the engine to purify and discharge exhaust gas generated in the engine.
[0004]
However, the DPF for collecting PM is clogged with the collection of PM, and the exhaust gas pressure (exhaust pressure) increases in proportion to the amount of collected PM. Several methods and devices have been developed.
[0005]
As one of them, a device called a continuous regeneration type DPF, which lowers the combustion start temperature of PM by the action of a catalyst such as γ-alumina, Pt, or zeolite supported on a filter and incinerates PM with exhaust gas, has been proposed. Yes.
[0006]
In the case of this continuous regeneration type diesel particulate filter (DPF) device, the temperature of the exhaust gas flowing into the DPF may be raised to a temperature for activating the catalyst (for example, about 250 ° C. or higher). .
[0007]
The mechanism for purifying PM in the exhaust gas differs depending on the engine operating range (torque and engine speed) (C1) and (C2) as shown in FIG.
[0008]
First, in the region (C1), the catalytic action of the filter with catalyst 4 (4CeO ₂ + C → 2CeO _Three + CO ₂ , 2CeO _Three + O ₂ → 4CeO ₂ ) Carbon (C: PM) to carbon dioxide (CO ₂ ) And in the region (C2), (C + O ₂ → CO ₂ ) Carbon (C: PM) to carbon dioxide (CO ₂ ) Is oxidized.
[0009]
Then, in the engine operating region (torque and engine speed) (C1), (C2) as shown in FIG. 11, the PM collected in the catalyst-equipped filter 4 is purified, so that the catalyst-equipped filter 4 is continuously used. The PM in the exhaust gas G is purified while being regenerated. In addition, although the division of (C1) and (C2) is schematically shown in FIG. 11, there is not necessarily a clear boundary line, and the main reaction gradually changes.
[0010]
[Problems to be solved by the invention]
However, in this continuous regeneration type DPF device, when the exhaust temperature corresponding to the engine operating region (D) in FIG. 11 is low, the catalyst temperature decreases and the catalytic activity decreases. In this case, PM cannot be regenerated by oxidizing the PM, so that there is a problem that PM is continuously deposited and the filter is clogged.
[0011]
In particular, during idle operation, low load operation, and engine braking operation on a downhill, fuel hardly burns, and low-temperature exhaust gas flows into the filter with catalyst. Decreases. Then, there is a problem that PM accumulates on the filter during the operation time when the filter cannot be regenerated, and the exhaust pressure rises.
[0012]
The present invention has been made to solve the above-described problems, and an object of the present invention is to control the exhaust gas temperature of an engine while monitoring the PM accumulation state in a continuous regeneration type diesel particulate filter device. Accordingly, it is an object of the present invention to provide a continuous regeneration type diesel particulate filter device capable of efficiently removing PM while reliably preventing clogging of the filter, and a control method thereof.
[0013]
[Means for Solving the Problems]
[Continuous regeneration type DPF device]
A continuous regeneration type particulate filter (DPF) device for achieving the above object is configured as follows.
[0014]
1) Collecting particulate matter in exhaust gas from diesel engines and burning the collected particulate matter by catalytic action A filter with a catalyst, an oxidation catalyst that oxidizes HC and CO in exhaust gas to raise the temperature of the exhaust gas upstream of the filter with catalyst, and a regeneration control that performs regeneration processing for clogging of the filter with catalyst In a continuous regeneration type diesel particulate filter device comprising means, The regeneration control means raises the exhaust gas temperature by fuel injection control of the engine and regenerates the oxidation catalyst during regeneration of the catalyst filter under engine operating conditions where the exhaust gas temperature of the engine is lower than the activation temperature of the oxidation catalyst. The particulate matter collected by the filter with catalyst is activated. Combusting and removing, and raising the temperature of the exhaust gas by the fuel injection control, a preheating stage for heating the oxidation catalyst and avoiding the generation of white smoke, and a stage for burning the particulate matter at a combustible temperature Perform in multiple steps Configured as follows.
[0015]
According to this configuration, the oxidation catalyst provided on the upstream side of the continuous regeneration type filter with a catalyst oxidizes carbon monoxide (CO), unburned fuel (HC), etc. in the exhaust gas to form a catalyst filter. Since the temperature of the exhaust gas flowing in can be raised, the temperature of the filter with the catalyst can be raised even when the engine is operating at a relatively low exhaust gas temperature, and the collected particulate matter (PM) Can be removed by burning.
[0016]
In the normal operation, when the trapped particulate matter is clogged in the low torque, low rotational speed engine operating state (A) where the collected particulate matter is not burned and removed, the main injection is as follows. By performing fuel injection control such as a delay operation (retarding) and post-injection (post-injection), the exhaust gas temperature is raised and PM is burned and removed.
[0018]
According to this configuration, in the continuous regeneration type diesel particulate filter device in the prior art, the exhaust gas temperature is low and the trapped particulate matter is not burned and removed, even in the operating state of a low torque, low rotational speed engine. By performing fuel injection control such as delaying the main injection timing (retarding) and post-injection (post-injection), the exhaust gas temperature rises and the oxidation catalyst is activated, and the exhaust gas temperature that has passed through this oxidation catalyst Can be further increased.
[0019]
Therefore, the temperature of the filter with catalyst rises, and the particulate matter collected by this filter with catalyst is burned and removed by the catalytic action of the filter with catalyst. Even during the downhill running operation that is activated, the filter with catalyst is not clogged and the particulate matter in the exhaust gas is continuously collected.
[0020]
Further, the combustion of the particulate matter is controlled by controlling the exhaust gas temperature by delaying the timing of the main injection of fuel injection or post-injection without using a heater. Can be performed by the existing fuel injection control device, and it is not necessary to add a new device such as a heater for heating or a power source or a new control device, and the entire device can be made compact. Therefore, the device can be easily attached to the vehicle.
[0022]
According to this configuration, when the exhaust gas temperature is raised in two or more stages, PM accumulated on the filter with catalyst is rapidly burned in a chain reaction, and runaway combustion occurs. It can be prevented that the temperature of the filter with catalyst becomes higher than the melting temperature and is damaged.
[0023]
2) In the continuous regeneration type diesel particulate filter device, the fuel injection control is Main injection delay operation and post injection operation Configured to include.
[0024]
According to this configuration, since the main injection delay operation and the post-injection operation are adopted as the fuel injection control, it can be handled only by changing the program of the existing fuel injection control device, and it is relatively easy. Filter regeneration is possible even in the low torque and low engine speed range of the engine.
[0025]
[Playback control method]
The regeneration control method for the continuous regeneration type diesel particulate filter device is configured as the following method.
[0026]
1) A filter with a catalyst for capturing particulate matter in exhaust gas of a diesel engine and burning the collected particulate matter by catalytic action, and HC and CO in the exhaust gas on the upstream side of the filter with catalyst. A continuous regeneration type diesel particulate filter device formed with an oxidation catalyst that oxidizes and raises an exhaust gas temperature, wherein the catalyst exhaust gas temperature of the engine is lower than an activation temperature of the oxidation catalyst under the engine operating condition When playing the attached filter, To the filter with catalyst In order to burn and remove the collected particulate matter, the exhaust gas temperature is controlled by fuel injection control of the engine. In addition to increasing the temperature, the temperature of the exhaust gas by the fuel injection control is increased in two stages: a preheating stage in which the oxidation catalyst is heated to avoid the generation of white smoke, and a stage in which the particulate matter is combusted at a combustible temperature. Perform in multiple steps Configured as a method.
[0027]
According to the above method, in the regeneration control method of the continuous regeneration type diesel particulate filter device in the prior art, the collected particulate matter is prevented from being burned and removed because the exhaust gas temperature is low and the oxidation catalyst activity is low. When the engine is running at a low torque and low rotational speed, fuel injection control such as retarding the main injection timing (retarding) and post-injection (post-injection) increases the exhaust gas temperature, and the oxidation catalyst Is activated, and the collected particulate matter is burned and removed by the catalytic action of the filter with catalyst, so even during idling operation, low speed operation and downhill driving operation that operates the engine brake, Catalytic filters continue to collect particulate matter in exhaust gas without clogging
[0029]
According to this method, when the exhaust gas temperature is raised in two or more stages, the PM deposited on the catalyst filter burns rapidly in a chain reaction, and the temperature of the catalyst filter is increased. It is possible to avoid damaging at the melting temperature or higher.
[0030]
2) In the regeneration control method for the continuous regeneration type diesel particulate filter device, the fuel injection control includes: Main injection delay operation and post injection operation Configured to include.
[0031]
According to this method, since the delay operation of the main injection timing and the post-injection are adopted as the fuel injection, it can be dealt with only by changing the program of the existing fuel injection control device, and the engine is relatively easy The filter with catalyst can be regenerated even in the low torque and low rotation speed region.
[0032]
3) During the regeneration by the regeneration control method of the continuous regeneration type diesel particulate filter device described above, the exhaust gas temperature is raised by first delaying the main injection of the fuel and flowing into the filter with catalyst After the temperature reaches a predetermined first target temperature value, a fuel post-injection operation is applied to further raise the exhaust gas temperature.
[0033]
According to this method, at the start of the regeneration mode operation, the exhaust gas temperature is increased by a delay operation of the main injection timing, the oxidation catalyst is preheated, the oxidation catalyst is activated, and then the post-injection is performed. White smoke that tends to occur at the start of regeneration can be prevented.
[0034]
4) In the regeneration control method for the continuous regeneration type diesel particulate filter device described above, in the post-combustion post-injection operation, a predetermined amount of post-injection of fuel is performed, and the temperature of the exhaust gas flowing into the catalyst-equipped filter is a predetermined second. After reaching the target temperature value, the fuel injection amount is increased to increase the exhaust gas temperature further.
[0035]
According to this method, the temperature of the exhaust gas entering the filter with the catalyst is raised in two stages or multiple stages, so that a rapid temperature rise due to the chained rapid combustion of the accumulated PM can be prevented. Melting of the attached filter is avoided.
[0036]
5) In the regeneration control method for the above-described continuous regeneration type diesel particulate filter device, the amount of particulate matter accumulated in the filter with catalyst and the amount of particulate matter burned and removed during engine operation are estimated from the operating state of the engine. The accumulated amount of particulate matter is estimated by cumulative calculation, and whether or not the estimated amount of accumulation of the particulate matter exceeds a predetermined accumulated amount is used to determine the start of regeneration. .
[0037]
According to this method, since the accumulated state of the particulate material is estimated and calculated, and when the accumulated estimated value of the particulate material exceeds a predetermined accumulated amount, the regeneration mode operation is started. It will be possible to do at the right time.
[0038]
Therefore, it is possible to efficiently collect and burn off particulate matter while preventing deterioration of fuel consumption.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a continuous regeneration type diesel particulate filter device (hereinafter referred to as a continuous regeneration type DPF device) according to an embodiment of the present invention will be described with reference to the drawings.
[0040]
[Device configuration]
FIG. 1 shows the configuration of the continuous regeneration type DPF device of this embodiment. The continuous regeneration type DPF device 1 is a device provided in the exhaust passage 2 of the engine E and provided with an oxidation catalyst 3 and a filter with catalyst 4 from the upstream side.
[0041]
For the regeneration control of the filter with catalyst 4, the first exhaust pressure sensor 51 is provided on the exhaust inlet side of the oxidation catalyst 3, and the first temperature sensor 53 is provided between the oxidation catalyst 3 and the filter with catalyst 4. A second exhaust pressure sensor 52 and a second temperature sensor 54 are provided on the exhaust outlet side of the filter 4.
[0042]
The output values of these sensors are input to and output from an engine control device (ECU: engine control unit) 50 that performs overall control of engine operation and also controls regeneration of the filter with catalyst 4. The engine fuel injection device 5 is controlled by the control signal.
[0043]
The oxidation catalyst 3 is formed by supporting an oxidation catalyst such as platinum (Pt), γ-alumina, or zeolite on a support such as a honeycomb structure of a porous ceramic, and the filter with catalyst 4 is a porous ceramic. Formed by a monolith honeycomb wall flow type filter in which the inlets and outlets of the honeycomb channels are alternately plugged, a felt-like filter in which inorganic fibers such as alumina are randomly laminated, and the like, Pt, It is formed by supporting a catalyst such as γ alumina or zeolite.
[0044]
When a monolith honeycomb wall flow type filter is used as the filter of the catalyst-equipped filter 4, particulate matter (hereinafter referred to as PM) in the exhaust gas G is collected by a porous ceramic wall ( When the fiber type filter type is employed, PM is collected by the inorganic fibers of the filter.
[0045]
[Playback control method]
Next, a regeneration control method in the continuous regeneration type DPF device 1 having the above configuration will be described.
[0046]
This reproduction control method is performed according to the flow illustrated in FIGS.
[0047]
These illustrated flows are shown as a regeneration control flow that is repeatedly called and executed in parallel with the control flow of the engine E for easy explanation. That is, during the operation control of the engine E, this flow is repeatedly called and executed at regular intervals, and when the control of the engine E is finished, this flow is not called and the regeneration control of the filter 4 with the catalyst is substantially performed. It is configured to end.
[0048]
[Outline of playback control method]
In the regeneration control flow of the present invention, not only when the exhaust pressure Pe detected by the first exhaust pressure sensor 51 exceeds the predetermined first exhaust pressure determination value Pemax, the start of the regeneration mode operation is performed, but also the filter with catalyst 4 This is also performed when the amount of accumulated PM, that is, the PM accumulated estimated value PMs becomes equal to or greater than a predetermined PM judgment value PMmax.
[0049]
In the regeneration control flow illustrated in FIG. 2, first, in step S21, the PM accumulated estimated value PMs is equal to or greater than a predetermined PM determination value PMmax, or the exhaust pressure Pe is equal to or greater than a predetermined first exhaust pressure determination value Pemax. If it is any, the process proceeds to the regeneration mode operation of step S30, and if none of them, the process returns.
[0050]
The flow of the regeneration mode operation in step S30 is the first stage of temperature increase in which preheating is performed by delaying (retarding) the timing of EGR (exhaust gas recirculation) in step S31 and the main injection (main) timing of fuel injection in step S32. , A second stage of temperature increase in which post-injection (post-injection) is performed in step S33 and fuel is injected by a specified amount to start PM combustion; This step comprises a fourth stage of temperature increase in which the post-injection amount of the post-injection is further increased and the PM is purged, and the regeneration mode operation is terminated in step S36.
[0051]
Hereinafter, each step will be described in detail.
[0052]
[Estimation of PM accumulated value]
The calculation of the PM cumulative estimated value PMs used for determining the shift to the regeneration mode operation in step S21 of FIG. 2 will be described in detail. This PM cumulative estimated value PMs is performed according to a PM cumulative estimation flow as illustrated in FIG.
[0053]
In the PM cumulative estimation flow of FIG. 3, when this flow starts, first, in step S <b> 11, the torque Q indicating the operating state of the engine E, the engine speed Ne, and the DPF measured by the first temperature sensor 53. Enter the inlet temperature T1.
[0054]
In the next step S12, the DPF inlet temperature Tb at the balance point (BP) is calculated from the map data Mtb (Q, Ne) inputted in advance from the torque Q and the engine speed Ne.
[0055]
This balance point is a region in which the collected PM does not burn and the PM accumulates because the exhaust gas temperature is low and the catalytic activity is low during the normal operation where the filter regeneration operation is not performed (FIG. 9). 9) and the region where the exhaust gas temperature is high and the collected PM is burned by the catalytic action and the accumulated PM is reduced (B portion in FIG. 9), the catalyst-equipped filter 4 This refers to a balanced portion (on line C in FIG. 9) in which neither PM accumulates nor decreases.
[0056]
In step S13, whether or not the measured DPF inlet temperature Te is equal to or lower than the DPF inlet temperature Tb at the balance point, that is, the region where the operating state of the engine E is low torque and low rotational speed PM accumulates ( It is determined whether or not it is within (A part of FIG. 9).
[0057]
If it is determined in step S13 that the measured DPF inlet temperature Te is equal to or lower than the DPF inlet temperature Tb at the balance point, that is, within the PM accumulation region (A), in FIG. ) PMa (Q, Ne) map is calculated from the PMa (Q, Ne) map corresponding to the torque Q and the engine speed Ne, and the accumulated PM amount for each time is calculated and added to the PM accumulated estimated value PMs.
[0058]
If the measured DPF inlet temperature Te is higher than the DPF inlet temperature Tb at the balance point, that is, within the PM decrease region (B portion in FIG. 9), it is input in advance in step S15. Further, the PM amount to be removed corresponding to the torque Q and the engine speed Ne is calculated from the PMb (Q, Ne) map of FIG. 9C, subtracted and accumulated in the PM accumulated estimated value PMs, and the process goes to step S16. .
[0059]
In this step S16, it is determined whether or not the PM accumulated estimated value PMs is greater than zero, that is, whether or not PM is in a deposited state. In the determination of this step S16, the PM accumulated estimated value PMs is less than zero. If it is smaller, the PM accumulated estimated value PMs is returned to zero in step S17, and if it is larger than zero, the process returns as it is.
[0060]
[Judgment to start regeneration mode operation]
In step S21 of FIG. 2, it is determined whether the PM accumulated estimated value PMs is equal to or greater than a predetermined PM determination value PMmax or whether the exhaust pressure Pe is equal to or greater than a predetermined first exhaust pressure determination value Pemax. In this determination of the PM accumulated estimated value PMs, as shown in FIG. 10A, the PM accumulated estimated value PMs is between PM1 and PM2, and the engine operating state (torque Q, engine rotation). (Ne) is in the hatched portion (A) below the balance point in FIG. 10B and when the PM accumulated estimated value PMs is between PM2 and PM3 in FIG. 10A (in this case) Is controlled so as to enter the regeneration mode operation when the engine operating state (torque Q, engine speed Ne) is the shaded portion (A + B) in FIG.
[0061]
[Temperature rise 1st stage: Preheating]
In step S32 of FIG. 2, the timing of main injection (main) of fuel injection is delayed (retarded), and the exhaust temperature is raised by this delay operation. In this step S32, the detailed flow of FIG. As shown in FIG. 4, in step S32a, the main injection is delayed, and the exhaust temperature is increased by this delay. The DPF inlet temperature (exhaust temperature) Te measured by the first temperature sensor 53 is determined in the next step S32b. Is determined to exceed a predetermined first target temperature Te1 (for example, 200 to 250 ° C.). If not, the delay amount of the main injection of the fuel injection is increased in step S32c, and this delay operation is performed. The DPF inlet temperature Te is raised to the first target temperature Te1 or higher.
[0062]
When the DPF inlet temperature Te exceeds the predetermined first target temperature Te1 and the predetermined first time value t1 has elapsed in step S32b, the process goes to step S33.
[0063]
By raising the exhaust temperature, preheating is performed to heat the oxidation catalyst 3, and the temperature of the catalyst is raised and activated, thereby avoiding generation of white smoke due to post-injection.
[0064]
This main injection delay operation is continued until the end of the regeneration mode operation.
[0065]
[Temperature rise second stage: PM combustion start]
In step S33 of FIG. 2, post injection is performed to post-inject a specified amount of fuel, and the exhaust gas temperature is increased until the DPF inlet temperature Te reaches the second target temperature Te2. The second target temperature Te2 is a temperature at which PM can be combusted as shown in FIG. is there.
[0066]
In step S33, as shown in the detailed flow of FIG. 5, in step S33a, a prescribed amount of post-injection is performed, and the DPF inlet temperature Te is further increased to the second target temperature Te2, and in the next step S33b, The second target temperature Te2 is controlled by controlling the timing of post-injection (injection timing) until the exhaust pressure Pe (or differential pressure ΔPe) becomes equal to or lower than a predetermined second exhaust pressure value Pe2b (or second differential pressure value ΔPe2). To maintain. Further, the injection amount may be controlled and maintained.
[0067]
This exhaust pressure Pe is the exhaust pressure value measured by the first exhaust pressure sensor 51 on the exhaust inlet side of the oxidation catalyst 3, and this differential pressure ΔPe is the exhaust pressure Pe measured by the first exhaust pressure sensor 51 and the catalyst attached. The difference ΔPe = Pe−Peb from the exhaust pressure Peb measured by the second exhaust pressure sensor 52 on the exhaust outlet side of the filter 4.
[0068]
In step S33c, the exhaust pressure Pe (or differential pressure ΔPe) becomes equal to or lower than a predetermined second exhaust pressure value Pe2 (or second differential pressure value ΔPe2), or the target temperature Te2 is set to a predetermined second time value. It is determined whether or not it has been maintained for t2 (for example, 300 s), and if any, the process proceeds to step S34, and if not, the process returns to step S33b.
[0069]
By this post-injection, the temperature of the filter with catalyst 4 is raised and PM combustion is started.
[0070]
Then, it is confirmed that the combustion of PM is started when the exhaust pressure Pe (or differential pressure ΔPe) is equal to or lower than a predetermined second exhaust pressure value Pe2 (or second differential pressure value ΔPe2).
[0071]
[Temperature rise third stage: PM combustion]
In the next step S34 of FIG. 2, the amount of post-injection is increased to increase the exhaust gas temperature so that the temperature becomes suitable for PM combustion, that is, the DPF inlet temperature Te is higher than the second target temperature Te2. Control is performed to achieve the third target temperature Te3. The third target temperature Te3 is about 350 ° C. to 500 ° C. at a predetermined temperature (for example, 150 ° C.) higher than the DPF inlet temperature Tb at the balance point.
[0072]
In step S34, as shown in the detailed flow of FIG. 6, the post-injection injection amount is increased in step S34a, and in the next step S34b, the exhaust pressure Pe (or differential pressure ΔPe) is set to a predetermined third. Until the exhaust pressure value Pe3 (or the third differential pressure value ΔPe3) or less, the post-injection injection amount is controlled to maintain the third target temperature Te3.
[0073]
In step S34c, the exhaust pressure Pe (or differential pressure ΔPe) becomes equal to or lower than a predetermined third exhaust pressure value Pe3 (or third differential pressure value ΔPe3), or the target temperature Te3 is set to a predetermined third time value. It is determined whether or not it has been maintained for t3 (for example, 600 s), and if any, the process proceeds to step S35, and if not, the process returns to step S34b.
[0074]
In this step S34, PM is burned at an optimum temperature by controlling the injection amount of post-injection.
[0075]
[Temperature rise stage 4: PM cleanup]
In step S35 of FIG. 2, the amount of post-injection is further increased, and control is performed so that the DPF inlet temperature Te becomes the fourth target temperature Te4 (for example, 600 ° C.).
[0076]
In step S35, as shown in the detailed flow of FIG. 7, the post-injection injection amount is increased in step S35a, and in the next step S35b, the exhaust pressure Pe (or differential pressure ΔPe) is a predetermined fourth value. Until the exhaust pressure value Pe4 (or the fourth differential pressure value ΔPe4) or less, the post-injection injection amount is controlled to maintain the fourth target temperature Te4.
[0077]
In step S35c, the exhaust pressure Pe (or differential pressure ΔPe) has become equal to or lower than a predetermined fourth exhaust pressure value Pe4 (or fourth differential pressure value ΔPe4), or the fourth target temperature Te4 is set to a predetermined fourth. It is determined whether or not it has been maintained for a time value t4 (for example, 300 s). If it is any, the process proceeds to step S36, and if not, the process returns to step S35b.
[0078]
By this temperature raising operation, the PM collected by the filter is wiped out.
[0079]
[End of regeneration mode operation]
Then, in step S36 shown in FIG. 2, the regeneration mode operation is terminated, the fuel injection is returned to normal, and the PM calculation cumulative value PMs is reset to zero.
[0080]
At the end of the regeneration, the exhaust pressure Pe is checked and stored, and when it exceeds a predetermined exhaust pressure value Pemax, a warning lamp is lit to inform the driver that the filter has reached the end of its life.
[0081]
[Others]
Further, at each stage of the above flow, the DPF inlet temperature Te is monitored, and when the temperature reaches or exceeds the limit temperature (Temax: 700 ° C., for example), the post-injection is stopped and the main injection delay operation is canceled. Thus, the regeneration mode operation is interrupted, thereby avoiding a filter erosion due to a rapid temperature rise due to PM combustion.
[0082]
At the same time, when the temperature Teb measured by the second temperature sensor 54 provided on the exhaust outlet side of the catalyst-equipped filter 4 exceeds a predetermined temperature, the torque of the filter 4 with the catalyst is automatically reduced. Operate the engine to prevent melting.
[0083]
When the regeneration process is interrupted, the remaining amount of PMs PMs is determined from the exhaust pressure Pe ′ at the end of the previous regeneration, the exhaust pressure Pe ”at the start of the current regeneration, and the exhaust pressure Pe at the time of regeneration suspension. 'Is estimated, and this PM remaining amount PMs' is adopted as a value at the start of accumulation of the PM accumulated estimated value PMs.
[0084]
Also, the first exhaust pressure value Pemax, the second exhaust pressure value Pe2 (or the second differential pressure value ΔPe2), the third exhaust pressure value Pe3 (or the third differential pressure value ΔPe3), and the fourth exhaust pressure value Pe4. The relationship (or the fourth differential pressure value ΔPe4) gradually decreases in this order. That is, Pemax>Pe2>Pe3> Pe4 (or ΔPe2>ΔPe3> ΔPe4).
[0085]
[Time series of playback]
According to the regeneration control method of the continuous regeneration type DPF device 1 as described above, the regeneration of the filter with catalyst 4 is performed in the time series of the DPF inlet temperature Te as shown in FIG.
[0086]
When PM is accumulated during engine operation such as a normal running state or an idle operation state, the PM accumulated estimated value PMs becomes larger than a predetermined determination value PMmax or the exhaust pressure Pe becomes larger than a predetermined first exhaust pressure value Pemax. By the determination in step S21 in FIG. 2, the process shifts to the reproduction mode in step S30.
[0087]
At this regeneration mode start time ts, EGR (exhaust gas recirculation) is cut in step S31, and the timing of main injection (main) of fuel injection is delayed (retarded) in step S32. To raise.
[0088]
When the DPF inlet temperature Te exceeds a predetermined first target temperature Te1 (about 200 to 250 ° C.), post injection (post-injection) is performed in step S33, and a predetermined amount of post injection is performed. The inlet temperature Te is raised to the second target temperature Te2 (about 350 ° C.), and PM combustion is started.
[0089]
Then, when it is confirmed that the combustion of PM is started by the exhaust pressure Pe (or differential pressure ΔPe) being equal to or lower than a predetermined second exhaust pressure value Pe2 (or second differential pressure value ΔPe2), in step S34. The post-injection amount is increased and the exhaust gas temperature is adjusted to a temperature suitable for PM combustion. The DPF inlet temperature Te is controlled so as to maintain the third target temperature Te3 (about 500 ° C.). PM is burned at the optimum temperature.
[0090]
Then, it is confirmed that most of the accumulated PM has been combusted by confirming that the exhaust pressure Pe (or differential pressure ΔPe) is equal to or lower than a predetermined third exhaust pressure value Pe3 (or third differential pressure value ΔPe3), and step S35. Then, the amount of post-injection is further increased, and the PM collected by the filter is cleared.
[0091]
Then, when the exhaust pressure Pe (or differential pressure ΔPe) is equal to or lower than a predetermined fourth exhaust pressure value Pe4 (or fourth differential pressure value ΔPe4), it is confirmed that the combustion of PM has ended, and in step S36, The regeneration mode operation is terminated, the fuel injection is returned to normal, and the PM calculation cumulative value PMs is reset to zero.
[0092]
By this series of regeneration control, the catalyst-equipped filter 4 is regenerated.
[0093]
【The invention's effect】
As described above, according to the continuous regeneration type diesel particulate filter (DPF) device and the regeneration control method thereof of the present invention, the following effects can be obtained.
[0094]
Exhaust gas flowing into the filter with catalyst by oxidizing gas components such as carbon monoxide (CO) and unburned fuel (HC) in the exhaust gas by the oxidation catalyst provided upstream of the filter with catalyst for continuous regeneration. Since the gas temperature can be raised, the temperature of the filter with the catalyst can be raised even when the engine is operating at a relatively low exhaust gas temperature, and the collected particulate matter (PM) can be burned and removed. .
[0095]
In normal operation, the exhaust gas temperature is reduced by delay operation of the main injection timing of fuel injection or post-injection in the operating state of the engine such as low torque and low rotation speed where the collected particulate matter is not burned and removed. By raising, PM can be removed by combustion.
[0096]
Therefore, the exhaust gas temperature is low, such as during idling operation for a long time, during low-speed operation and during downhill driving operation that activates the engine brake, and the low torque at which the collected PM is not burned off, Even in an engine operating state such as a low engine speed, PM in exhaust gas can be continuously collected without clogging the filter with catalyst.
[0097]
Further, without using a heater, PM combustion is controlled by controlling the exhaust gas temperature by delaying the main injection or post-injection of fuel, and this fuel injection can be performed by an existing fuel injection control device. Therefore, new equipment such as a heater and a power source for heating and its control device can be dispensed with, and thus the device can be made compact.
[0098]
In addition, since the temperature of the exhaust gas entering the filter with catalyst is raised in two stages or multiple stages, it is possible to prevent a sudden increase in temperature due to chained rapid combustion of the accumulated PM. Loss can be avoided.
[0099]
In addition, since the regeneration mode operation is started based on the accumulated PM estimated value, the regeneration process of the filter with catalyst can be performed at the optimum timing. Therefore, it is possible to continuously and efficiently collect and burn and remove PM while preventing deterioration of fuel consumption.
[0100]
Furthermore, at the start of the regeneration mode operation, the exhaust gas temperature is increased by delaying the main injection timing, the oxidation catalyst is preheated to activate the catalyst, and then the post-injection is performed. The generation of white smoke can be prevented.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a continuous regeneration type particulate filter device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a regeneration control method of the continuous regeneration type particulate filter device according to the embodiment of the present invention.
FIG. 3 is a flowchart for estimating and calculating a PM accumulated estimated value.
FIG. 4 is a flow chart of a first stage of temperature increase of preheating due to delay of main injection of fuel injection.
FIG. 5 is a flowchart of a second stage of temperature increase at the start of PM combustion by post-injection of a prescribed amount of fuel injection.
FIG. 6 is a flow chart of a third stage of temperature increase of PM combustion due to an increase in post-injection of fuel injection.
FIG. 7 is a flowchart of a fourth stage of temperature rise for PM cleaning by further increase in post-injection of fuel.
FIG. 8 is a time-series diagram showing the passage of time of the DPF inlet temperature in the regeneration mode operation.
9A and 9B are diagrams showing map data of PM amount used for calculating the PM accumulated estimated value, FIG. 9A is a diagram showing a balance point, and FIG. 9B is a portion where map data of the PM accumulation area (A) is present. (C) is a figure which shows a part with the map data of PM removal area | region (B).
FIGS. 10A and 10B are diagrams for determining the PM accumulated estimated value at the start of regeneration mode operation, where FIG. 10A is a diagram showing a relationship between a numerical value used for determination and a regeneration interval, and FIG. 10B is a diagram when PM1 ≦ PMs <PM2. (C) is a figure which shows an engine operation area | region (A + B) at the time of PM2 <= PMs <PM3.
FIG. 11 is a diagram illustrating a relationship between an engine operating region (torque and engine speed) and a mechanism for purifying PM in exhaust gas in a conventional continuous regeneration type particulate filter device.
[Explanation of symbols]
E engine
1 Continuous regeneration type particulate filter device
2 Exhaust passage
3 Oxidation catalyst
4 Filter with catalyst
5 Fuel injector
50 Control unit (ECU)
51 First exhaust pressure sensor
52 Second exhaust pressure sensor
53 First temperature sensor
54 Second temperature sensor

Claims (7)

Catalytic filter that collects particulate matter in exhaust gas of diesel engine and burns the collected particulate matter by catalytic action , and oxidizes HC and CO in exhaust gas upstream of the filter with catalyst In the continuous regeneration type diesel particulate filter device comprising an oxidation catalyst for raising the exhaust gas temperature and a regeneration control means for performing regeneration processing for clogging of the catalyst-attached filter,
The regeneration control means raises the exhaust gas temperature by fuel injection control of the engine and regenerates the oxidation catalyst during regeneration of the catalyst filter under engine operating conditions where the exhaust gas temperature of the engine is lower than the activation temperature of the oxidation catalyst. A preheating stage in which the particulate matter trapped in the filter with catalyst is burned and removed, and the exhaust gas temperature is raised by the fuel injection control to heat the oxidation catalyst and avoid the generation of white smoke And a continuous regeneration type diesel particulate filter device, characterized in that it is configured to perform in two or more stages of burning particulate matter at a combustible temperature . The continuous regeneration type diesel particulate filter device according to claim 1, wherein the fuel injection control performs a delay operation and a post-injection operation of main injection. A filter with a catalyst that collects particulate matter in exhaust gas of a diesel engine and burns the collected particulate matter by catalytic action, and oxidizes HC and CO in the exhaust gas upstream of the filter with catalyst. In a continuously regenerating diesel particulate filter device formed with an oxidation catalyst for raising the exhaust gas temperature by
In order to burn and remove particulate matter trapped in the catalyst-coated filter during regeneration of the catalyst-filter under engine operating conditions where the engine exhaust gas temperature is lower than the activation temperature of the oxidation catalyst, engine fuel injection The exhaust gas temperature is raised by control to activate the oxidation catalyst, and the particulate matter trapped in the catalyst-equipped filter is burned and removed, and the exhaust gas temperature rise by the fuel injection control is increased by the oxidation catalyst. Continuously recycle diesel, characterized in that it is composed of two or more stages, a preheating stage that heats the gas and avoids the generation of white smoke, and a stage that burns particulate matter at a combustible temperature A regeneration control method for a particulate filter device. 2. The regeneration control method for a continuous regeneration type diesel particulate filter device according to claim 1, wherein the fuel injection control executes a delay operation and a post-injection operation of main injection. During the regeneration, the exhaust gas temperature is first raised by delaying the main injection of the fuel, and after the temperature of the exhaust gas flowing into the filter with catalyst reaches a predetermined first target temperature value, The regeneration control method for a continuous regeneration type diesel particulate filter device according to claim 4, wherein the exhaust gas temperature is further raised by applying a fuel post-injection operation . In the post-combustion operation of the combustion, after the post-injection of the specified amount of fuel is performed and the temperature of the exhaust gas flowing into the filter with catalyst reaches a predetermined second target temperature value, the injection amount of the fuel post-injection is set. 6. The regeneration control method for a continuous regeneration type diesel particulate filter device according to claim 5, wherein the exhaust gas temperature is further increased to further increase the exhaust gas temperature . Estimate the amount of particulate matter accumulated in the filter with catalyst and the amount of particulate matter burned and removed during engine operation from the operating state of the engine, and calculate the accumulated amount of particulate matter by cumulative calculation 7. The method according to claim 3, wherein the estimated accumulation amount of the particulate matter exceeds a predetermined accumulation amount for use in determining whether to start regeneration. Control method for continuous regeneration type diesel particulate filter device.

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