JP2005282478A - Control method of exhaust emission control system and exhaust emission control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method of an exhaust emission control system and the exhaust emission control system by which misfire and generation of white smoke can be prevented by forced regeneration control when an engine is not heated with regard to forced regeneration control executing cylinder fuel injection control of multi-injection, post injection or the like so as to regenerate DPF of a continuous regeneration type DPF device. <P>SOLUTION: In the exhaust emission control system 1 equipped with a continuous regeneration type DPF device 13 in an exhaust gas passage 12 of an engine 10 and with a cooling water temperature detecting means 341C for detecting temperature Twm of cooling water in the engine 10, even when forced regeneration is determined to be necessary and when the temperature Twm of cooling water in the engine 10 which is detected by the cooling water temperature detecting means 341C is detected to be lower than the prescribed water temperature Tw0 for determination, the cylinder fuel injection control for forced regeneration of DPF 13a is not executed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control method for an exhaust gas purification system for purifying particulate matter (PM) by exhaust gas from an internal combustion engine such as a diesel engine using a continuous regeneration type diesel particulate filter (DPF) device, and exhaust gas purification. It is about the system.

  Particulate matter (PM: particulate matter: hereinafter referred to as PM) emitted from diesel engines is being regulated more and more with NOx, CO, HC, etc., and this PM is used as a diesel particulate filter. A technique for reducing the amount of PM collected by a filter called (DPF: Diesel Particulate Filter: hereinafter referred to as DPF) and discharged to the outside has been developed.

  DPFs that collect PM include ceramic monolith honeycomb wall flow type filters, fiber type filters made of ceramic or metal fibers, and exhaust gas purification systems using these DPFs. As with other exhaust gas purification systems, it is installed in the middle of the exhaust passage of the engine to purify and discharge exhaust gas generated by the engine.

  In these DPF devices, a continuous regeneration type DPF device in which an oxidation catalyst is provided on the upstream side of the DPF, or a continuous combustion type in which the PM combustion temperature is lowered by the action of the catalyst supported on the catalyst-equipped filter, and the PM is incinerated with exhaust gas There are regenerative DPF devices and the like.

This upstream regeneration catalyst continuous regeneration type DPF device utilizes the fact that oxidation of PM by NO ₂ (nitrogen dioxide) is performed at a low temperature by oxidizing PM with oxygen in exhaust gas. The catalyst is composed of a catalyst and a filter, and the upstream side of the oxidation catalyst carrying platinum or the like oxidizes NO (nitrogen monoxide) in the exhaust gas to NO ₂ , and with this NO ₂ , the downstream filter The collected PM is oxidized to CO ₂ (carbon dioxide) to remove the PM.

Moreover, the continuous regeneration type DPF device for a filter with a catalyst is constituted by a filter with a catalyst having a catalyst such as cerium oxide (CeO ₂ ), and in the exhaust gas in the filter with a catalyst in a low temperature range (about 300 ° C. to 600 ° C.). oxidizing the PM by the O ₂ reaction using _{(oxygen) (4CeO 2 + C → 2Ce} 2 O 3 + CO 2, 2Ce 2 O 3 + O 2 → 4CeO 2 , etc.), PM is burned with O ₂ in the exhaust gas In a high temperature range (about 600 ° C. or higher) higher than the temperature, PM is oxidized by O ₂ in the exhaust gas.

  And even in the continuous regeneration type DPF device etc. of this filter with a catalyst, an oxidation catalyst is provided on the upstream side, and by preventing the unburned HC and CO in the exhaust gas from being released into the atmosphere, The exhaust gas temperature at the rear stage PM filter inlet is raised to promote PM oxidation removal.

  However, even in these continuous regeneration type DPF devices, when the exhaust gas temperature is 350 ° C. or higher, PM collected by this filter is continuously burned and purified, and the filter self-regenerates, but the exhaust temperature is When the engine is in low operating conditions or low exhaust emissions, such as when the engine is idling or under low exhaust temperature conditions such as low load / low speed operation, the exhaust gas temperature is low and the catalyst temperature decreases. Therefore, the oxidation reaction is not promoted, and since NO is insufficient, the above reaction does not occur, and the filter cannot be regenerated by oxidizing the PM. Filter clogging progresses. Therefore, the problem of an increase in exhaust pressure due to the clogging of the filter occurs.

  For this clogging of the filter, when the clogging exceeds a predetermined clogging amount, it is considered that the exhaust temperature is forcibly raised to forcibly remove the collected PM. Yes. The filter clogging detection means includes a method of detecting by the differential pressure across the filter, a method of detecting by the travel distance, and calculating the PM amount collected from the operating state of the engine from map data set in advance. Then, there is a method for obtaining and detecting the PM accumulated amount, and as a means for raising the exhaust temperature, a method by injection control in in-cylinder (in-cylinder) injection or by fuel control in direct fuel injection into the exhaust pipe There is a way.

  This in-cylinder injection control performs multi-injection (multistage injection) to raise the temperature of the exhaust gas when the exhaust temperature is lower than the activation temperature of the oxidation catalyst provided upstream of the filter or the oxidation catalyst supported on the filter. When the temperature rises above the activation temperature, post-injection (post-injection) is performed, and the fuel in the exhaust gas is burned by the oxidation catalyst, and the exhaust gas is heated to a temperature higher than the temperature at which the PM collected by the filter burns. The PM collected by the filter is burned and removed to regenerate the filter.

Normally, in these continuous regeneration type DPF devices, when the accumulated amount of PM reaches a preset accumulation limit value of PM, the engine operating state is automatically changed to the forced regeneration mode operation to set the exhaust temperature. The regeneration process is performed by forcibly increasing or increasing the amount of NO or NO ₂ to oxidize and remove the PM collected by the filter.

  However, in the in-cylinder (in-cylinder) fuel injection control, in order to raise the exhaust temperature, when performing multi-injection or post-injection in which the injection timing is delayed as much as possible, the state of the engine itself, for example, warm-up The engine coolant temperature may not be sufficiently high due to the process being performed. When this cooling water temperature is low, the temperature at the time of ignition in the cylinder is low, so that it becomes a bad ignition environment for fuel injection with this injection timing delayed, and misfires or white smoke due to insufficient combustion occurs. There is a problem of doing. Further, if the fuel injection timing is advanced to avoid this, there arises a problem that the exhaust temperature necessary for regeneration of the DPF cannot be obtained.

  On the other hand, when the regeneration of the DPF is performed by post-injection, in order to prevent white smoke from being generated, the amount of generated heat can be removed at the initial stage of the regeneration of the DPF so that the exhaust particulates (PM) collected by the DPF can be removed. A fuel injection control device for an internal combustion engine that gradually increases the post-injection injection amount toward a suitable basic injection amount has been proposed.

  However, this fuel injection control device for an internal combustion engine is intended to solve the problem of white smoke generation related to the oxidation capability of the oxidation catalyst, and in-cylinder fuel injection in a state where engine warm-up is insufficient. Since there is no countermeasure against misfire or white smoke due to multi-injection or post-injection in Japan, it is not a solution to these problems.

Further, in this fuel injection control device for an internal combustion engine, the control is always to gradually increase the post injection, so that there is a problem that the time for PM combustion removal becomes longer and the fuel consumption deteriorates.
JP 2004-11446 A

  An object of the present invention relates to forced regeneration control that performs in-cylinder fuel injection control such as multi-injection and post-injection to regenerate the DPF of the continuous regeneration type DPF device, misfire caused by forced regeneration control when the engine is not warmed, An object of the present invention is to provide an exhaust gas purification system control method and an exhaust gas purification system capable of preventing the generation of white smoke.

  In order to achieve the above object, a method for controlling an exhaust gas purification system according to the present invention includes a continuous regeneration type diesel particulate filter (hereinafter referred to as DPF) device in an exhaust gas passage of an engine mounted on a vehicle. The amount of collected particulate matter detection means in the regenerative DPF device, the cooling water temperature detection means for detecting the temperature of the engine cooling water, and the in-cylinder fuel injection control to raise the exhaust temperature and force it This is a case where it is determined that forced regeneration is necessary in an exhaust gas purification system having a DPF control means having a forced regeneration means for combusting collected particulate matter and regenerating the continuous regeneration type DPF device. However, if it is detected that the temperature of the engine cooling water detected by the cooling water temperature detecting means is lower than a predetermined water temperature for determination, forced regeneration is performed. Configured so as not to of the in-cylinder fuel injection control.

  An exhaust gas purification system of the present invention for achieving the above object includes a continuous regeneration type DPF device in an exhaust gas passage of an engine mounted on a vehicle, and the particulate matter in the continuous regeneration type DPF device. Collected amount detection means for detecting the amount of fuel, cooling water temperature detection means for detecting the temperature of the engine cooling water, and combustion of particulate matter that has been forcibly collected by raising the exhaust gas temperature by in-cylinder fuel injection control In the exhaust gas purification system having the DPF control means having the forced regeneration means for regenerating the continuous regeneration type DPF device, the DPF control means determines that the forced regeneration by the forced regeneration means is necessary. However, if it is detected that the temperature of the engine coolant detected by the coolant temperature detecting means is lower than a predetermined water temperature for determination, the forced regeneration Configured to control so as not to inner fuel injection control.

  In the exhaust gas purification system, the in-cylinder fuel injection control is configured to include at least one or both of multi-injection control and post-injection control.

  The continuous regeneration type DPF device in the exhaust gas purification system described above includes a continuous regeneration type DPF device in which an oxidation catalyst is supported on a filter, a continuous regeneration type DPF device in which an oxidation catalyst is provided upstream of the filter, and a catalyst in the filter. And a continuous regeneration type DPF device in which an oxidation catalyst is provided on the upstream side of the filter.

  According to the exhaust gas purification system control method and exhaust gas purification system of the present invention, in-cylinder fuel injection control such as multi-injection and post-injection when the temperature of engine coolant is lower than a predetermined water temperature for determination. It is configured not to perform forced regeneration control that includes, and forced regeneration control is performed after the temperature of the cooling water has risen reliably. This prevents problems such as deterioration of drivability due to engine misfire and generation of white smoke. it can.

  Hereinafter, as for an exhaust gas purification system control method and an exhaust gas purification system according to an embodiment of the present invention, an example of an exhaust gas purification system including a continuous regeneration type DPF device constituted by a combination of an oxidation catalyst and a filter with a catalyst will be described. This will be described with reference to the drawings.

  FIG. 1 shows a configuration of an engine exhaust gas purification system 1 according to this embodiment. The exhaust gas purification system 1 is configured by providing a continuous regeneration type DPF (diesel particulate filter) device 13 in an exhaust passage 12 connected to an exhaust manifold 11 of a diesel engine 10. The continuous regeneration type DPF device 13 includes an oxidation catalyst (DOC) 13a on the upstream side and a filter with catalyst (CSF) 13b on the downstream side.

  This oxidation catalyst 13a is formed by carrying an oxidation catalyst such as platinum (Pt) on a carrier such as a porous ceramic honeycomb structure, and the filter with catalyst 13b is formed at the inlet of the channel of the porous ceramic honeycomb. And a monolith honeycomb wall flow type filter in which the outlets are alternately sealed, or a felt-like filter in which inorganic fibers such as alumina are laminated at random. A catalyst such as platinum or cerium oxide is supported on the filter.

  When a monolith honeycomb wall flow type filter is adopted as the filter with catalyst 13b, PM (particulate matter) in the exhaust gas G is collected (trapped) by the porous ceramic wall, and the fibers When the mold filter type is adopted, PM is collected by the inorganic fibers of the filter.

  Then, in order to estimate the amount of PM deposited on the filter with catalyst 13b, a differential pressure sensor 21 is provided in a conducting pipe connected before and after the continuous regeneration type DPF device 13. For regeneration control of the filter with catalyst 13b, an oxidation catalyst inlet exhaust temperature sensor 22 and a filter inlet exhaust temperature sensor are provided on the upstream side, the middle, and the downstream side of the oxidation catalyst 13a and the filter with catalyst 13b, respectively. An air cleaner 18 is provided in the intake passage 17.

  Output values of these sensors are input to a control device (ECU: engine control unit) 30 that performs overall control of the operation of the engine 10 and also performs regeneration control of the continuous regeneration type DPF device 13. An exhaust throttle valve 16 that is provided downstream of the fuel injection device (injection nozzle) 14 of the engine 10 and the continuous regeneration type DPF device 13 in the exhaust passage 12 according to the control signal output from An EGR valve or the like that adjusts the EGR amount provided in the EGR passage together with the EGR cooler is controlled.

  The fuel injection device 14 is connected to a common rail injection system (not shown) that temporarily stores high-pressure fuel boosted by a fuel pump (not shown). In addition to information such as the accelerator opening from the accelerator position sensor (APS) 31, the engine speed from the rotation speed sensor 32, the travel distance from the travel distance sensor 33, the temperature of the engine coolant from the water temperature sensor 34, the vehicle Speed etc. are also input.

  As shown in FIG. 2, the control device 30 includes an engine control means 20C for controlling the operation of the engine, a DPF control means 30C for the exhaust gas purification system 1, and the like. The DPF control means 30C includes a normal operation control means 31C, a PM collection amount detection means 32C, a travel distance detection means 33C, a forced regeneration means 34C, a warning means 35C, and the like.

  The normal operation detection means 31C is a means for performing a normal operation that is performed regardless of the regeneration of the continuous regeneration type DPF device 13, and based on the signal of the accelerator position sensor 31 and the signal of the rotation speed sensor 32. Normal injection control in which a predetermined amount of fuel is injected from the fuel injection device 14 is performed based on the energization time signal calculated by the control device 30.

  The PM trapping amount detection means 32C is a means for detecting the trapping amount ΔPm of PM (particulate matter) trapped in the filter 13b with catalyst of the continuous regeneration type DPF device 13, and detecting the trapping amount ΔPm. Is detected from the accumulated calculation value of the accumulation amount estimated from the engine speed and load, the engine rotation accumulation time, the differential pressure before and after the continuous regeneration type DPF device 13, and the like. In this embodiment, detection is performed based on the differential pressure before and after the continuous regeneration type DPF device 13, that is, based on the measured value by the differential pressure sensor 21.

  The travel distance detection means 33C is a means for detecting the distance ΔMc traveled by the vehicle after the DPF regeneration. The travel distance detection means 33C is obtained based on the travel distance measured by the travel distance sensor 33, and when the forced regeneration is performed. The time is reset at an appropriate time from the start of playback to the end of playback.

  The forced regeneration means 34C is slightly different in control depending on the type of the continuous regeneration type DPF device 13, but performs multi-injection (multistage injection) in the cylinder (in-cylinder) injection of the engine 10 to change the exhaust temperature to the oxidation catalyst 13a. Is increased to the activation temperature, and then post-injection (post-injection) is performed to increase the filter inlet exhaust temperature Tfi detected by the filter inlet exhaust temperature sensor 23 to 500 ° C. to 600 ° C. The PM collected in the filter 13b with catalyst is forcibly burned and removed to forcibly regenerate the filter 13b with catalyst. In addition, intake system control such as the exhaust throttle valve 16 and EGR is used in combination as necessary.

  In the present invention, the forced regeneration means 34C includes a cooling water temperature detecting means 341C that detects the temperature Twm of the engine cooling water, and the engine cooling water detected by the cooling water temperature detecting means 341C. When the temperature Twm is lower than a predetermined determination water temperature Tw0, the multi-injection control and the post-injection control are not performed, and the process waits until the detected cooling water temperature Twm becomes higher than the predetermined determination water temperature Tw0. Then, the multi-injection control and the post-injection control are performed after it becomes high, and the filter 13b with catalyst is forcibly regenerated.

  The warning unit 35C includes a flashing lamp (DPF lamp) 41, a warning lamp (warning lamp) 42, and the like, and warns the driver (driver) of urging the manual regeneration means 34C to operate manually by the flashing of the flashing lamp 41. It is a means for urging the driver to take the vehicle to the service center by going on or turning on the warning light 42. The driver who has received this warning can operate the forced regeneration means 34C by operating the manual regeneration switch 43.

  The DPF control means 30C having these various means includes the PM collection amount ΔPm detected by the PM collection amount detection means 32C and the travel distance ΔMc after the DPF regeneration detected by the travel distance detection means 33C. Based on the above, means for continuing normal operation by the normal operation control means 31C, warning the driver for manually operating the forced regeneration means 34C, or automatically operating the forced regeneration means 34C Configured as

  Next, regeneration control of the exhaust gas purification system 1 will be described. In the control of the exhaust gas purification system 1, a normal operation is performed by the normal operation control means 31C and PM is collected. In this normal operation, examples are shown in FIGS. 3 and 4 at appropriate time intervals. The control according to the reproduction control flow is performed. With this control, whether the PM collection amount ΔPm detected by the PM collection amount detection means 31C and the travel distance ΔMc detected by the travel distance detection means 32C fall within a predetermined range, whether manual regeneration is possible or not. Then, it is determined whether or not the automatic driving regeneration is possible, and after performing various processes as necessary, the process returns to the normal operation by the normal operation control means 31C. Then, the vehicle is driven while repeating normal driving and regeneration control.

  The regeneration control flow of FIGS. 3 and 4 will be described with reference to the regeneration control map of FIG. 5 used for determining whether or not forced regeneration control is necessary.

  First, the regeneration control map of FIG. 5 will be described. In the regeneration control map schematically shown in FIG. 5, the vertical axis represents the amount of PM (collected matter) collected (in this embodiment, the differential pressure). ) P, and the area of the trapped amount ΔP is defined by three threshold values of a first threshold value (predetermined trapped amount for determination) ΔP1, a second threshold value ΔP2, and a third threshold value ΔP3. The area is divided into four areas of a second collection amount area Rp2, a third collection amount area Rp3, and a fourth collection amount area Rp4. The horizontal axis indicates the travel distance ΔM, and the region of the travel distance ΔM is defined as the first travel distance with three threshold values: a first threshold (predetermined travel distance for determination) ΔM1, a second threshold ΔM2, and a third threshold ΔM3. The area is divided into four areas: an area Rm1, a second travel distance area Rm2, a third travel distance area Rm3, and a fourth travel distance area Rm4. Then, the region where the current state is is determined by the reproduction control, and the following processing is performed as necessary.

  The first threshold value (predetermined travel distance for determination) ΔM1 is a value indicating a lower limit that does not cause a problem due to oil dilution in the case of manual forced regeneration, and the second threshold value ΔM2 is a travel value. This is a value indicating the lower limit at which no problem due to oil dilution occurs when forced regeneration is automatically performed. Further, the third threshold value ΔM3 is a value for performing forced regeneration in order to prevent thermal runaway due to PM uneven accumulation and DPF meltdown in the filter with catalyst 13b. The fourth travel distance region Rm4 is a region that exceeds the third threshold value ΔM3, and automatically performs forced regeneration or automatically turns on a warning light.

  First, when the detected travel distance ΔMc is in the first travel distance region Rm1 without exceeding the first threshold value ΔM1, if the forced regeneration is performed manually, the fuel in the oil is not sufficiently evaporated. As a result, oil dilution problems arise. Therefore, in this case, manual forced regeneration is prohibited. Even in this case, depending on the travel pattern, the accumulated amount of PM per travel distance is large, and the detected collection amount ΔPm exceeds the third threshold value ΔP3 and enters the fourth collection amount region Rp4. In this case, in order to avoid thermal runaway, in which PM trapped in the continuous regeneration type DPF device 13 starts self-combustion and sudden PM combustion occurs, manual regeneration and automatic traveling are performed. A warning lamp 42 is lit to urge the driver to bring the vehicle to a service center such as a dealer, while prohibiting the reproduction. In the service center, for example, backwashing with air or baking for a long time at an intermediate temperature is performed, and the filter is regenerated while avoiding melting damage of the filter.

  Next, when the detected travel distance ΔMc exceeds the first threshold value ΔM1 and enters the second travel distance region Rm2, the travel is still insufficient and the fuel mixed in the engine oil has been sufficiently evaporated. Since there is no automatic forced regeneration, a warning for prompting manual regeneration in which the vehicle is stopped and forced regeneration is performed manually is performed, but a different warning is performed depending on the detected collection amount ΔPm.

  While the detected collection amount ΔPm is smaller than the first threshold (predetermined collection amount for determination) ΔP1, the clogging of the filter 13b with catalyst is small and the operation of the forced regeneration means 34C is not necessary, so that Continue normal operation. When the detected collection amount ΔPm exceeds the first threshold value (predetermined collection amount for determination) ΔP1, but enters the second differential pressure region Rp2 that does not exceed the second threshold value ΔP2, In order to avoid the problem of oil dilution during forced regeneration, automatic regeneration is prohibited and the flashing lamp (DPF lamp) 41 flashes slowly (manual flashing 1) to stop the vehicle from the driver. Encourage manual forced regeneration (manual regeneration: manual regeneration).

  Further, when the detected collection amount ΔPm exceeds the second threshold value ΔP2, but enters the third differential pressure region Rp3 that does not exceed the third threshold value ΔP3, the oil dilution during forced regeneration is In order to avoid the problem, the automatic driving regeneration is prohibited, and the blinking lamp 41 blinks quickly (manual blinking 2), and the driver is strongly urged to perform manual regeneration after stopping the vehicle. When entering the third differential pressure region Rp3, depending on the operation state, the PM trapped in the continuous regeneration type DPF device 13 starts self-combustion and causes a thermal runaway that is rapid PM combustion, Since there is a high possibility that the filter with catalyst 13b will be melted, the amount of injected fuel is throttled in consideration of this self-ignition.

  When the detected collection amount ΔPm exceeds the third threshold value ΔP3 and enters the fourth differential pressure region Rp4, in order to avoid thermal runaway, do not perform manual regeneration and automatic traveling regeneration. The warning light 42 is turned on to prompt the driver to take it to the service center.

  Next, when the detected travel distance ΔMc exceeds the second threshold value ΔM2 and enters the third travel distance region Rm3, the fuel mixed in the engine oil is sufficiently evaporated, and the automatic forced regeneration during travel ( When the detected collection amount ΔPm exceeds the first threshold value (predetermined collection amount for determination) ΔP1 and enters the second collection amount region Rp2, the vehicle travels automatically. Automatic running regeneration that automatically activates the forced regeneration means 34C is performed. This traveling automatic regeneration prevents the driver from being burdened with manual forced regeneration, that is, ON / OFF operation of the manual regeneration switch 43. Note that while the detected collection amount ΔPm is smaller than the first threshold value (predetermined collection amount for determination) ΔP1, the clogged filter 13b is not clogged, and there is no need to operate the forced regeneration means 34C. Continue normal operation.

  When the detected traveling distance ΔMc exceeds the third threshold value ΔM3 and enters the fourth traveling distance region Rm4, the fuel mixed in the engine oil is sufficiently evaporated, and automatic forced regeneration during traveling is possible. Therefore, in the range where the detected collection amount ΔPm does not exceed the third threshold value ΔP3, regardless of the detected differential pressure ΔPm, the forced regeneration during traveling is always performed and the accumulated PM is Incinerate. However, when the detected collection amount ΔPm exceeds the third threshold value ΔP3 and enters the fourth differential pressure region Rp4, manual regeneration and automatic traveling regeneration are prohibited in order to avoid thermal runaway, The warning light 42 is turned on to prompt the driver to take it to the service center.

  The control shown in the regeneration control map as shown in FIG. 5 can be performed by the regeneration control flow as exemplified in FIG. When the regeneration control flow of FIG. 3 starts, it is determined in step S10 whether or not the detected travel distance ΔMc exceeds a first threshold value (predetermined travel distance for determination) ΔM1. In this determination, if it is not exceeded but is in the first travel distance region Rm1, it is determined in step S11 whether or not the detected collection amount ΔPm exceeds the third threshold value ΔP3. If not, return as it is and continue normal operation. On the other hand, if it exceeds, the warning lamp 42 is turned on in step S12 and the process returns.

  Accordingly, when it is determined in step S10 that the vehicle is in the first travel distance region Rm1, manual operation of the forced regeneration means 34C is prohibited. In addition, automatic traveling regeneration in which the forced regeneration means 34C is automatically activated during traveling of the vehicle is not performed.

  If the travel distance ΔMc exceeds the first threshold value (predetermined travel distance for determination) ΔM1 in step S10, it is determined in step S20 whether the travel distance ΔMc exceeds the second threshold value ΔM2. To do. In this determination, if it does not exceed, it is determined in step S21 whether or not the collection amount ΔPm exceeds the first threshold value (predetermined collection amount for determination) ΔP1. Continue normal operation.

  If the collection amount ΔPm exceeds the first threshold value (predetermined collection amount for determination) ΔP1 in step S21, it is determined in step S22 whether the collection amount ΔPm exceeds the second threshold value ΔP2. If it does not exceed, the flashing lamp (DPF lamp) 41 is slowly turned on in step S24, and whether the manual regeneration switch is ON or OFF is determined in step S26.

  Further, when the collection amount ΔPm exceeds the second threshold value ΔP2 in the determination in step S22, it is determined whether or not the collection amount ΔPm exceeds the third threshold value ΔP3 in step S23. In step S25, the blinking lamp (DPF lamp) 41 is quickly turned on, and in step S26, it is determined whether the manual regeneration switch is on or off.

  If the manual regeneration switch 43 is ON in step S26, manual regeneration is performed by operating the manual regeneration switch 43 in step S26 to operate the forced regeneration means 34C. In step S28, the counter of the travel distance ΔMc is reset. Return. Further, when the trapping amount ΔPm is determined not by the differential pressure but by the accumulated amount of PM, the accumulated amount of PM is also reset. On the other hand, if the manual regeneration switch 43 is not ON in step S26, the process directly returns and waits for the manual regeneration switch 43 to be turned ON by the driver during the repetition of this regeneration control flow.

  If it is determined in step S23 that the collected amount ΔPm exceeds the third threshold value ΔP3, the warning light 42 is turned on in step S29 and the process returns with manual regeneration and automatic traveling regeneration prohibited. .

  If it is determined in step S20 that the travel distance ΔMc exceeds the second threshold value ΔM2, it is determined in step S30 whether the travel distance ΔMc exceeds the third threshold value ΔM3. If it is determined in step S30 that it has exceeded, it is determined in step S31 whether or not the collection amount ΔPm exceeds the first threshold value (predetermined collection amount for determination) ΔP1. If it is determined in step S31 that it has not exceeded, the routine returns and the normal operation is continued. On the other hand, if it exceeds the determination in step S31, the determination goes to step S32. And even if it is not exceeded by determination of step S30, it goes to determination of step S32.

  In step S32, it is determined whether or not the collection amount ΔPm exceeds the third threshold value ΔP3. If so, manual regeneration and automatic traveling regeneration are prohibited. In step S35, the warning lamp 42 is turned on. Turns on and returns.

  If it is determined in step S32 that the collected amount ΔPm does not exceed the third threshold value ΔP3, in step S33, automatic regeneration is performed to automatically operate the forced regeneration means 34C during traveling, and in step S34. The travel distance ΔMc counter is reset and the process returns. Further, when the trapping amount ΔPm is determined not by the differential pressure but by the accumulated amount of PM, the accumulated amount of PM is also reset.

  In the present invention, in the manual regeneration in step S27 for operating the forced regeneration means 34C and the automatic traveling regeneration in step S33, multi-injection control and post-injection control are performed in a control flow as shown in FIG. The filter with catalyst 13b is regenerated.

  In the control flow shown in FIG. 4, when it is called and started in step S27 or step S33 of the control flow of FIG. 3, the temperature Twm of the engine coolant detected by the water temperature sensor 34 is set in advance in step S41. It is determined whether or not the temperature is equal to or higher than a predetermined water temperature for determination Tw0. If it is small, there is a risk that misfires may occur during multi-injection or post-injection if forced regeneration is started immediately, and white smoke may be emitted. , The warm-up system is activated, the warm-up operation is performed for a predetermined time related to the determination interval of the cooling water temperature Twm, the process returns to step S41, and the cooling water temperature Twm is equal to or higher than the predetermined determination water temperature Tw0. Wait until it rises.

  If it is determined in step S41 that the cooling water temperature Twm is equal to or higher than a predetermined determination water temperature Tw0, the forced regeneration system is allowed to operate in step S43, and the exhaust gas temperature is checked in step S44. That is, it is determined whether or not the exhaust gas temperature Tdi detected by the oxidation catalyst inlet exhaust gas temperature sensor 22 is lower than a predetermined determination temperature Td0.

  If the exhaust gas temperature Tdi is smaller than the predetermined determination temperature Td0 in the exhaust gas temperature check in step S44, the first forced regeneration control for performing multi-injection in step S45 is set as an interval for determining the completion of the regeneration control. For a predetermined time of interest. Thereafter, in step S47, it is determined whether or not the reproduction control is completed. The first forced regeneration control is a control for increasing the exhaust temperature Tdi to the activation temperature Td0 of the oxidation catalyst 13a by performing multi-injection (multi-stage injection) in the cylinder (in-cylinder) injection of the engine 10.

  If the exhaust gas temperature Tdi is equal to or higher than the predetermined determination temperature Td0 in the exhaust gas temperature check in step S44, the completion of the regeneration control is determined in the second forced regeneration control in which the multi-injection and post-injection are performed in step S46. For a predetermined time related to the interval. In this second forced regeneration control, post-injection (post-injection) is performed together with multi-injection, and the filter inlet exhaust temperature Tfi detected by the filter inlet exhaust temperature sensor 23 is raised to 500 ° C. to 600 ° C. to remove PM by oxidation. An appropriate temperature and environment are set, and the PM collected by the filter with catalyst 13b is forcibly burned and removed to forcibly regenerate the filter with catalyst 13b. Thereafter, in step S47, it is determined whether or not the reproduction control is completed. In this forced regeneration, intake system controls such as the exhaust throttle valve 16 and EGR are used together as necessary. Alternatively, the second forced regeneration control may be performed by multi-injection and direct fuel injection in the exhaust passage by supplying unburned fuel into the exhaust gas by direct fuel injection in the exhaust passage instead of post injection. .

  In step S47, the regeneration control is determined based on whether or not a preset regeneration processing time has elapsed, whether or not the differential pressure ΔPm detected by the differential pressure sensor 21 has become equal to or less than a predetermined completion determination differential pressure value ΔPm1, and the like. To do.

  If it is determined in step S47 that the regeneration control is not completed, the process returns to step S41, and steps S41 to S47 are repeated until completion is obtained.

  If it is determined in step S47 that the regeneration control has been completed, the control flow in FIG. 4 is terminated and the process returns, and the process returns to the control flow in FIG.

  According to the control of the exhaust gas purification system described above, when the engine coolant temperature Twm is lower than the predetermined determination water temperature Tw0, forced injection including in-cylinder fuel injection control such as multi-injection control and post-injection control is performed. The forced regeneration control can be performed only when the temperature Twm of the engine cooling water is equal to or higher than the predetermined determination water temperature Tw0 without performing the regeneration control.

  Therefore, it is possible to prevent the problem that the drivability is deteriorated or white smoke is generated due to misfire at the initial stage of regeneration in the forced regeneration control when the temperature of the cooling water of the engine is low.

  In the above description, the continuous regeneration type DPF device in the exhaust gas purification system is described as an example of the continuous regeneration type DPF device in which the catalyst is supported on the filter and the oxidation catalyst is provided on the upstream side of the filter. The present invention is not limited to this, and other types of continuous regeneration types such as a continuous regeneration type DPF device in which an oxidation catalyst is supported on a filter and a continuous regeneration type DPF device in which an oxidation catalyst is provided on the upstream side of the filter. It can also be applied to a DPF device.

1 is a system configuration diagram of an exhaust gas purification system according to an embodiment of the present invention. It is a figure which shows the structure of the control means of the exhaust gas purification system of embodiment which concerns on this invention. It is a figure which shows the regeneration control flow of the exhaust gas purification system of embodiment which concerns on this invention. It is a figure which shows the control flow of forced regeneration control of embodiment which concerns on this invention. It is a figure which shows typically the map for regeneration control of the exhaust gas purification system of embodiment which concerns on this invention.

Explanation of symbols

1 Exhaust gas purification system
10 Diesel engine (internal combustion engine)
13 Continuous regeneration type DPF device
13a Oxidation catalyst
13b Filter with catalyst
30 control unit (ECU)
34 Water temperature sensor
30C DPF control means
31C Normal operation control means
32C PM collection amount detection means
33C Travel distance detection means
34C Forced regeneration means
341C Cooling water temperature detection means
35C Warning means
Twm Engine coolant temperature
Tw0 Predetermined water temperature for judgment

Claims (3)

A collection amount detection means for detecting a trapped amount of particulate matter in the continuous regeneration type diesel particulate filter device, provided with a continuous regeneration type diesel particulate filter device in an exhaust gas passage of an engine mounted on a vehicle; Cooling water temperature detecting means for detecting the cooling water temperature of the engine, and the continuously regenerating diesel particulate filter device by burning the particulate matter forcedly collected by raising the exhaust gas temperature by in-cylinder fuel injection control In an exhaust gas purification system comprising a diesel particulate filter control means having a forced regeneration means for regenerating
Even when it is determined that forced regeneration is necessary, when it is detected that the temperature of the engine coolant detected by the coolant temperature detecting means is lower than a predetermined determination water temperature, the forced regeneration is performed. A control method for an exhaust gas purification system, wherein the in-cylinder fuel injection control is not performed. A continuous regeneration type diesel particulate filter device is provided in an exhaust gas passage of an engine mounted on a vehicle, and a collection amount detection means for detecting the amount of particulate matter in the continuous regeneration type diesel particulate filter device, Cooling water temperature detection means for detecting the temperature of the cooling water, and the particulate matter collected forcibly by raising the exhaust temperature by in-cylinder fuel injection control to burn the continuously regenerated diesel particulate filter device In an exhaust gas purification system comprising diesel particulate filter control means having forced regeneration means
Even when the diesel particulate filter control means determines that the forced regeneration by the forced regeneration means is necessary, the temperature of the engine coolant detected by the coolant temperature detection means is higher than a predetermined judgment water temperature. An exhaust gas purification system that performs control so that the in-cylinder fuel injection control for forced regeneration is not performed when low is detected. The exhaust gas purification system according to claim 2, wherein the in-cylinder fuel injection control includes at least one or both of multi-injection control and post-injection control.

Images