JP2011111949A - Dpf regeneration control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure an amount of oxygen to be supplied to a DPF and avoid insufficient increase in a temperature in the DPF when regenerating the DPF so as to surely regenerate the DPF. <P>SOLUTION: A temperature increase control means 32 for performing a post injection by suppressing the amount of oxygen within exhaust gas so as to increase a temperature in a DPF 3 to a predetermined temperature and an oxygen supply control means 31 for combusting PM by supplying oxygen to the DPF 3 after the temperature in the DPF 3 is increased to the predetermined temperature are provided. The temperature increase control means 32 includes a temperature determination means 33 for determining whether a temperature in the DPF 3 is increased to a predetermined temperature after predetermined time is elapsed from the start of the post injection, an oxygen amount determination means 34 for determining, when the temperature in the DPF 3 is determined as not being increased to the predetermined temperature, whether the amount of the oxygen supplied to the DPF 3 is below a predetermined value, and a device correction means 35 for performing, when the amount of the oxygen supplied to the DPF 3 is determined to be below the predetermined value, a correction operation to an exhaust gas temperature increasing device for increasing a temperature of the exhaust gas. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a regeneration technique for a filter (DPF) that collects and removes particulate matter in exhaust gas from a diesel engine, and more particularly to a regeneration technique for a DPF that is performed in an idle operation state including manual regeneration.

  Vehicles equipped with diesel engines (hereinafter also simply referred to as engines) usually contain particulate matter such as soot (Particulate Matter, hereinafter abbreviated as PM) in the exhaust, which is released directly 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). .

  The DPF has a limit in 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 a predetermined value, Then, DPF regeneration processing for removing PM accumulated in the DPF is performed. In this DPF regeneration method, fuel is supplied to an oxidation catalyst disposed upstream of the DPF, and the exhaust temperature is increased by combustion of the fuel on the oxidation catalyst. A method of forced regeneration is known in which the temperature is raised to a predetermined temperature and the PM is forcibly burned. By removing PM accumulated in the DPF in this way, the clogging of the DPF is eliminated, and the collection ability is recovered (regenerated).

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 the automatic regeneration in which stable combustion is difficult, the excessively accumulated PM may burn at a time and cause thermal damage to the filter. Regeneration is preferred. Manual regeneration is generally performed in an idle operation state. However, in the idle operation state, the exhaust temperature is unlikely to rise, so how to raise the exhaust temperature is important.

  By the way, the PM collected in the DPF is burned vigorously by combustion propagation when oxygen is supplied at once after the DPF temperature is set to a predetermined temperature (PM combustion temperature) at which the PM burns. It is known that can be obtained (see, for example, Patent Document 2). In this case, when the combustion of PM by combustion propagation is started, if the amount of oxygen is sufficient, the combustion by combustion propagation is maintained until all of the collected PM is removed even if the amount of oxygen falls below that predetermined temperature.

  However, if oxygen is present in the DPF before the temperature of the DPF rises to a predetermined temperature at which PM burns, the PM gradually starts to burn by an oxidation reaction as the temperature of the DPF approaches the predetermined temperature. The density of PM decreases. Therefore, even if the temperature of the DPF subsequently reaches the PM combustion temperature, combustion propagation hardly occurs, and the combustion speed becomes slower than when oxygen is supplied all at once after reaching the PM combustion temperature, so the time required for regeneration is prolonged. Further, there is a problem that PM remains unburned and the recovery of exhaust pressure is insufficient, leading to deterioration in drivability and fuel consumption during normal driving.

  Therefore, for example, as in the exhaust gas purification device described in Patent Document 2, the oxygen concentration in the exhaust gas is lowered until the DPF temperature rises to the PM combustion temperature, and after the DPF temperature reaches the PM combustion temperature, Techniques for controlling the oxygen concentration in exhaust gas to be high have been proposed. In this exhaust purification system, in order to reduce the oxygen concentration in the exhaust, the target intake air amount for rich operation is obtained from the engine speed and the fuel injection amount, and the opening of the intake throttle is adjusted so as to obtain this value. To do.

  In this state, in order to raise the exhaust gas temperature, post injection, which is additional fuel injection in the expansion stroke or the exhaust stroke, is performed while feeding back the air-fuel ratio. After the temperature of the DPF reaches the PM combustion temperature, the intake throttle is opened to switch to lean operation, and the oxygen concentration in the exhaust is increased to burn PM at a stroke.

Japanese Patent No. 3925472 JP 2002-213229 A

  However, depending on the usage environment of the vehicle, the temperature of the DPF may not rise to a predetermined temperature at which PM burns even if the post-injection is performed in the rich operation by narrowing the intake throttle during the regeneration operation of the DPF. It was found that it occurred. As a result of investigating the cause, when the vehicle is used in an increased load for driving auxiliary equipment, increased friction at low temperatures, and low oxygen conditions due to high altitudes, the target intake is simply determined from the engine speed and fuel injection amount. When the amount of air was obtained and the intake throttle was controlled to achieve a low oxygen state, it was found that the state was actually a very low oxygen state due to excessive oxygen throttling.

  In other words, in the driving situation where oxygen is required or in the state where oxygen is low, the intake air amount is obtained in the same way as during normal operation, and the oxygen concentration is actually reduced by simply reducing the intake throttle opening and reducing the oxygen concentration. There may be a very low oxygen state in which only an amount of air smaller than the amount of air is inhaled and the oxygen concentration is very low. In this state, no matter how much post-injection is performed for regeneration of the DPF, the amount of oxygen is insufficient, and the DPF does not rise in temperature, so that PM deposited on the DPF cannot be removed. Furthermore, post-injection performed in an oxygen-deficient state is wasteful fuel injection, which causes oil dilution.

  In particular, manual regeneration performed in a state where PM is excessively accumulated is generally performed in an idle operation state. However, in the idle operation state, the exhaust temperature does not easily increase, and thus the exhaust temperature is increased to raise the DPF. Must be done more strictly and reliably. For this purpose, it is necessary to appropriately control the intake throttle opening so that the amount of oxygen supplied to the DPF does not become excessive or insufficient particularly during manual regeneration performed in the idle state.

  The present invention has been devised in view of such problems. In the regeneration process of the DPF performed in the idle operation state including the manual regeneration, the amount of oxygen supplied to the DPF is secured, and the temperature rise of the DPF is prevented. An object of the present invention is to provide a DPF regeneration control device that avoids the problem and can reliably regenerate the DPF.

  In order to solve the above problems, the DPF regeneration control device of the present invention regenerates the DPF by removing the PM from the filter (DPF) that collects particulate matter (PM) contained in the exhaust of the diesel engine. A DPF regeneration control device that increases the temperature of the DPF to a predetermined temperature at which the PM can be combusted by suppressing post-injection while suppressing the amount of oxygen in the exhaust when the PM accumulates over a predetermined value. Control means, and oxygen supply control means for supplying oxygen to the DPF and burning the PM when the temperature of the DPF rises to the predetermined temperature by temperature increase control by the temperature increase control means, The temperature control means includes a temperature determination means for determining whether the temperature of the DPF has risen to the predetermined temperature after a predetermined time has elapsed since the start of the post injection, and the temperature determination means The temperature is An oxygen amount determination means for determining whether the amount of oxygen supplied to the DPF is less than a predetermined value when it is determined that the temperature has not been raised to a constant temperature; and an oxygen amount supplied to the DPF by the oxygen amount determination means Device correction means for correcting the exhaust gas temperature raising device for raising the exhaust gas temperature when it is determined to be less than a predetermined value.

The regeneration of the DPF is preferably performed in an idle operation state including manual regeneration.
The exhaust temperature raising device may include an oxygen amount adjusting device that is any one or more of an intake throttle, a fuel injection device, a variable displacement turbocharger, and an exhaust brake. preferable.
The exhaust temperature raising device preferably includes one or both of the fuel injection device and a common rail for storing high-pressure fuel.

  According to the DPF regeneration control device of the present invention, when the amount of oxygen supplied to the DPF does not reach a predetermined value, the exhaust temperature can be raised by performing a correction operation on the exhaust temperature raising device. In addition, it is possible to avoid a temperature increase failure of the DPF due to excessive throttling of oxygen. Therefore, the regeneration of the DPF can be surely performed, and unnecessary post injection can be avoided, so that oil dilution can be reduced.

Further, whether the amount of oxygen supplied to the DPF is insufficient is determined after the DPF temperature has not reached the predetermined temperature even though a predetermined time has elapsed since the start of post injection. Since the determination of the oxygen amount is performed only when necessary, only the minimum necessary calculation needs to be performed.
In particular, when regeneration of the DPF is performed in an idle operation state including manual regeneration, the exhaust temperature must be raised to raise the DPF more strictly and reliably. Since the exhaust gas temperature can be raised by performing a correction operation on the device, the regeneration of the DPF can be reliably performed.

  Further, the exhaust temperature raising device includes an oxygen amount adjusting device which is any one or more of an intake throttle, a fuel injection device, a variable displacement turbocharger, and an exhaust brake. By correcting the oxygen amount adjusting device, the amount of oxygen supplied to the DPF can be ensured. In addition, if any one of the oxygen amount adjusting devices is sufficient, the correction operation can be easily performed. If any one of the oxygen amount adjusting devices cannot secure the oxygen amount, a plurality of combinations can be reliably used. The amount of oxygen can be secured.

  Since the exhaust temperature raising device further includes one or both of the fuel injection device and the common rail, it is possible to raise the exhaust temperature by performing a correction operation on these devices. Regeneration can be performed more reliably.

It is the schematic which shows the structure around the diesel engine mounted in the vehicle to which the DPF regeneration control apparatus concerning one Embodiment of this invention is applied. It is a flowchart shown about the DPF regeneration control process by the DPF regeneration control apparatus concerning one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 illustrate a DPF regeneration control device according to an embodiment of the present invention. FIG. 1 is a schematic diagram showing a structure around a diesel engine to which the DPF regeneration control device is applied, and FIG. It is a flowchart shown about the DPF regeneration control process by a regeneration control apparatus. The present embodiment is DPF regeneration control that is performed in an idle operation state including manual regeneration.

  As shown in FIG. 1, a diesel engine (also simply referred to as an engine) 1 according to this embodiment is accommodated in an engine room of a vehicle (not shown). A cylinder block (not shown) of the engine 1 is provided with a cylinder 13, and a piston 14 is provided in the cylinder 13 so as to be able to reciprocate up and down. The piston 14 is connected to a crankshaft (not shown) via a connecting rod 15, and a crank angle sensor 22 that detects the rotation angle of the crankshaft is provided in the engine 1.

  A cylinder head (not shown) of the engine 1 is provided with an injector (fuel injection device) 5 toward the center of the top of the combustion chamber (not shown) on the top surface side of the piston 14, and a common rail is connected from a fuel pump (not shown). When the fuel is fed through the injector 5, the injector 5 is opened and the fuel is injected into the combustion chamber. In addition, fuel injection is performed in five times by a common rail (not shown). In order to adjust the fuel injection pressure, a common rail pressure sensor 25 for detecting the pressure of fuel in a rail (not shown) is provided. The water temperature sensor 24 detects the temperature of engine coolant.

  Downstream of the exhaust brake 8 provided in the exhaust passage 11 is a DPF (Diesel Particulate Filter) 3 for collecting PM (Particulate Matter, particulate matter) such as soot contained in the exhaust gas of the engine 1. Is provided. The exhaust brake 8 is an auxiliary brake device used in the engine 1 and closes a valve provided in the exhaust passage 11 to make it difficult to emit exhaust gas, thereby preventing engine rotation and generating a powerful engine brake. In addition, an actuator 20 is provided to drive the exhaust brake 8.

  An oxidation catalyst 16 that oxidizes and purifies harmful HC (hydrocarbon) and CO (carbon monoxide) contained in the exhaust gas is provided upstream of the DPF 3, and a catalyst temperature sensor is provided upstream of the oxidation catalyst 16. 26 is provided. The injector 5 is used to supply fuel to the oxidation catalyst 16 upstream of the DPF 3 by post-injection or the like that injects fuel at a timing at which combustion does not occur in the combustion chamber (mainly during the exhaust process). Oxidation reaction (combustion) is performed, the exhaust gas temperature is raised, and PM of DPF 3 is incinerated and removed to regenerate DPF 3. Exhaust temperature sensors 27 are provided on the upstream side and the downstream side of the DPF 3, respectively.

  A variable capacity turbocharger (hereinafter also referred to as a VG turbocharger) 2 capable of adjusting the supercharging pressure is accommodated in the engine room together with the engine 1. The VG turbocharger 2 uses exhaust gas from the engine 1 in a turbine (not shown), drives a coaxial compressor (not shown), and supercharges the engine 1 with high-pressure air. A variable nozzle vane mechanism (not shown) is provided on the side, and the supercharging pressure can be controlled by controlling the nozzle opening degree according to engine conditions and adjusting the opening area of the exhaust turbine. An actuator 17 is provided for driving the VG turbocharger 2.

  An air cleaner 4 that removes dust and dirt in the intake air (fresh air) is provided at the uppermost stream of the intake passage 10, and an air flow sensor 28 that detects an intake air amount is provided immediately downstream of the air cleaner 4. . Further, an outlet of an EGR passage 12 branched from the middle of the exhaust passage 11 is connected to the downstream side of the intake throttle 7 provided in the intake passage 10. The EGR passage 12 is provided with an EGR valve 6 that opens and closes the passage 12, so that part of the exhaust gas discharged from the engine 1 can be returned to the intake passage 10 and introduced into the combustion chamber. . The intake throttle 7 adjusts the amount of air supplied to the engine 1 and is driven by an actuator 18. The EGR valve 6 is driven by an actuator 19.

  Further, the intake passage 10 is provided with an intake pressure sensor 21 for detecting the pressure of intake air. The intake pressure sensor 21 also has a function of estimating the supercharging pressure of the VG turbocharger 2. That is, if the supercharging pressure of the VG turbocharger 2 changes, the pressure detected by the intake pressure sensor 21 provided in the intake passage 10 also changes, so the pressure detected by the intake pressure sensor 21 is changed to the VG turbocharger 2. It is estimated as the supercharging pressure.

In addition to the above, an accelerator opening sensor 23 for detecting the accelerator depression amount and a DPF cleaning switch 9 that is pushed by the driver when the DPF 3 needs to be regenerated are provided. And the regeneration request for DPF 3 are detected.
Information from these various sensors and switches is sent to an engine control device (hereinafter referred to as engine ECU) 30, and various controls are performed by the engine ECU 30. The engine ECU 30 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 a signal between the outside Are provided with an input / output port and the like.

  Then, the engine ECU 30 functions as a temperature increase control means 32 that raises the temperature of the DPF 3 in order to regenerate the DPF 3, a function element as the oxygen supply control means 31 that supplies oxygen to the DPF 3, a fuel Functional elements as fuel injection control means 36 for performing injection, functional elements as VG turbocharger control means 37 for controlling the supercharging pressure of the VG turbocharger 2, and intake throttle control for controlling the throttle valve of the intake throttle 7 A functional element as means 38, a functional element as exhaust brake control means 39 for controlling the valve of the exhaust brake 8, and a functional element as common rail pressure control means 40 for controlling the pressure of fuel in the common rail. Yes. In addition to this, the engine ECU 30 also has a function of determining that the regeneration of the DPF 3 is necessary when PM is excessively accumulated in the DPF 3 and notifying the driver that the regeneration is necessary.

  When the PM accumulates in the DPF 3 at a predetermined value or more, the temperature raising control means 32 suppresses the amount of oxygen in the exhaust gas and performs the post injection by the injector 5, and the temperature of the DPF 3 is a predetermined temperature at which PM can be combusted (PM combustion temperature) Let the temperature rise. The temperature increase control means 32 further determines whether or not the functional element as the temperature determination means 33 for determining whether the temperature of the DPF 3 has increased to a predetermined temperature and whether the amount of oxygen supplied to the DPF 3 is less than a predetermined value. As a device correction unit 35 for performing a correction operation on the exhaust gas temperature raising device for raising the exhaust temperature when the functional element as the oxygen amount judgment unit 34 to perform and the amount of oxygen supplied to the DPF 3 is less than a predetermined value And functional elements.

  The temperature determination means 33 detects the temperature of the DPF 3 by the exhaust temperature sensor 27 after a predetermined time has elapsed since the start of post injection by the injector 5, and determines whether the temperature of the DPF 3 has risen to the predetermined temperature. That is, even if post injection is performed, there is a slight distance from the combustion chamber to the oxidation catalyst 16, so the time from when the post injection is started until the fuel reaches the oxidation catalyst 16 is defined as a predetermined time. After the time elapses, it is determined whether the temperature of the DPF 3 has been raised to the PM combustion temperature.

The predetermined time that is the arrival determination time from the start of post injection until reaching the oxidation catalyst 16 is calculated by detecting the intake air amount by the air flow sensor 28 and calculating the exhaust flow rate from the intake air amount and the fuel injection amount. The exhaust flow rate is calculated in correspondence with a one-dimensional map stored in advance.
The predetermined temperature that is the determination threshold value for the temperature rise of the DPF 3 is calculated by associating the fuel amount post-injected by the injector 5 with a one-dimensional map stored in advance, but is not limited to this. There is also a method for calculating the post-injected fuel amount and the calculated exhaust flow rate in correspondence with a two-dimensional map stored in advance.

The oxygen amount determination unit 34 determines whether the amount of oxygen supplied to the DPF 3 is less than a predetermined value when the temperature determination unit 33 determines that the temperature of the DPF 3 has not increased to a predetermined temperature. Normally, post-injection is performed by the injector 5, and if this fuel undergoes an oxidation reaction (combustion) with the oxidation catalyst 16, the exhaust temperature rises to a predetermined temperature at which PM can be combusted. However, depending on the usage environment of the vehicle, there are cases where the temperature of the DPF 3 does not rise to a predetermined temperature even when post injection is performed. At that time, it is determined whether or not the amount of oxygen supplied to the DPF 3 is excessively reduced.
The predetermined value serving as a determination threshold value for the amount of oxygen supplied to the DPF 3 is calculated by associating the post-injected fuel amount with a one-dimensional map stored in advance.

  The device correction unit 35 determines that the oxygen amount supplied to the DPF 3 is less than the predetermined value by the oxygen amount determination unit 34, that is, the temperature of the DPF 3 is lower than the predetermined temperature and the oxygen amount is insufficient. If it is, correct the exhaust temperature raising device for raising the exhaust temperature. The correction of the exhaust temperature raising device will be described later.

When the temperature of the DPF 3 rises to a predetermined temperature by the temperature increase control by the temperature increase control unit 32 including the temperature determination unit 33, the oxygen amount determination unit 34, and the device correction unit 35, the oxygen supply control unit 31 supplies oxygen to the DPF 3. The supplied PM is combusted at once.
The fuel injection control means 36 controls all fuel injections by the injector 5. That is, pre-injection (pilot injection) for noise reduction and No _x reduction, main injection for obtaining ideal engine 1 power, after-injection for PM reduction, and the temperature of the DPF 3 by the temperature rise control means 32 Is a post-injection for regenerating the DPF 3 by raising the temperature to a predetermined temperature.

The VG turbocharger control means 37 adjusts the opening area of the exhaust turbine of the VG turbocharger 2 and controls the supercharging pressure. In particular, in order to raise the exhaust temperature during the regeneration operation, the opening area is widened and the supercharging pressure is controlled to be low.
The intake throttle control means 38 controls the opening of the intake throttle 7 and adjusts the amount of intake air (fresh air). In particular, in order to raise the exhaust temperature during the regeneration operation, the opening of the intake throttle 7 is throttled to control the intake air amount to be reduced.

The exhaust brake control means 39 controls the exhaust brake 8 to make it difficult to emit exhaust gas, thereby preventing engine rotation and generating a powerful engine brake. In particular, in order to raise the exhaust gas temperature during the regeneration operation, control is performed to reduce the amount of exhaust gas by closing the valve.
The common rail pressure control means 40 controls the pressure of fuel in a common rail (not shown) so that fuel can be easily mixed with air so that fuel can be injected at a high pressure.

  This DPF regeneration control device includes an oxygen supply control means 31 provided as a functional element of the engine ECU 30, a temperature determination means 33, an oxygen amount determination means 34, and a device correction means 35. It consists of.

Here, the device correction unit 35 will be described.
As described above, the device correction unit 35 raises the exhaust gas temperature when the oxygen amount determination unit 34 determines that the oxygen amount supplied to the DPF 3 is less than a predetermined value during the regeneration operation of the DPF 3. Correct the exhaust temperature rise device. The exhaust gas temperature raising device includes an oxygen amount adjusting device that is one or more of the VG turbocharger 2, the injector (fuel injection device) 5, the intake throttle 7, and the exhaust brake 8. It is. The oxygen amount adjusting device is a correction device that increases the amount of oxygen supplied to the DPF 3 and raises the exhaust gas temperature.

  In order to increase the amount of oxygen supplied to the DPF 3, the device correction unit 35 controls the oxygen amount adjusting devices, respectively, a VG turbocharger control unit 37, a fuel injection control unit 36, and an intake throttle control unit. A command to increase the amount of oxygen is sent to 38 and the exhaust brake control means 39.

  That is, the VG turbocharger control means 37 controls the nozzle opening of the VG turbocharger 2 during the regeneration operation so as to widen the opening area of the exhaust turbine and lower the supercharging pressure. When a command to increase the amount of oxygen is received from the correction means 35, the nozzle opening is decreased, the opening area of the exhaust turbine is narrowed, and the boost pressure is increased to increase the intake air amount.

The fuel injection control unit 36 after-injects a certain amount of fuel during the regeneration operation in order to reduce PM. However, when a command to increase the amount of oxygen is received from the device correction unit 35, the fuel injection control unit 36 decreases the amount of fuel to be injected after. Correction is performed, the amount of oxygen consumed by after-injection is reduced, and that amount of oxygen is supplied to the DPF 3.
The intake throttle control means 38 controls to reduce the opening of the intake throttle 7 and reduce the intake air amount in order to raise the exhaust temperature during the regeneration operation, but increases the oxygen amount from the device correction means 35. When the command is received, the opening degree of the intake throttle 7 is increased and correction for increasing the intake air amount is performed.

The exhaust brake control means 39 controls to reduce the amount of exhaust gas by closing the valve in order to raise the exhaust temperature during the regeneration operation. However, when receiving an instruction from the device correction means 35 to increase the amount of oxygen, the exhaust brake control means 39 The valve of the brake 8 is opened, and correction for increasing the amount of exhaust gas is performed.
The exhaust temperature raising device further includes one or both of an injector (fuel injection device) 5 and a common rail (not shown). The device correction unit 35 then sends a command to raise the exhaust temperature to the fuel injection control unit 36 and the common rail pressure control unit 40 that control the injector 5 and the common rail, respectively.

When the fuel injection control unit 36 receives a command from the device correction unit 35 to raise the exhaust gas temperature in addition to a command to increase the amount of oxygen, the timing of main injection by the injector (fuel injection device) 5 is advanced. Perform correction to shift to the side.
When the common rail pressure control unit 40 receives a command from the device correction unit 35 to raise the exhaust gas temperature, the common rail pressure control unit 40 performs correction to increase the pressure of the fuel in the common rail.

  Note that the device correction means 35 may correct the same device again when the temperature of the DPF 3 is lower than the predetermined temperature and the amount of oxygen is insufficient even if the device correction is performed once. For example, the intake throttle 7, the after-injection amount by the injector 5, the VG turbocharger 2, the exhaust brake 8, the main injection timing by the injector 5, and the common rail are corrected in this order with priority. Good. Further, when the correction operation is performed by a plurality of devices, it is preferable to select a device according to the deficient oxygen amount at that time.

Since the DPF regeneration control device according to the present embodiment is configured as described above, the DPF regeneration control according to the present embodiment is performed according to the flowchart shown in FIG.
As shown in FIG. 2, it is first determined whether or not the regeneration of the DPF 3 is being performed by the engine ECU 30 (step S1). In this determination method, the engine ECU 30 calculates how much PM is accumulated in the DPF 3, and when the PM accumulation amount is equal to or greater than a certain reference value, for example, the driver requests the driver to regenerate the DPF 3, and the driver If the DPF cleaning switch 9 is pressed, it may be determined that the DPF 3 is being regenerated, or otherwise, the engine ECU 30 may automatically perform the regeneration and determine that the DPF 3 is being regenerated.

  In step S1, if the DPF 3 is being regenerated, it is determined whether the vehicle is idling (step S2), and if it is idling, it is determined whether post-injection is being performed. (Step S3). This is because the post-injection is not performed immediately after the regeneration operation is started, and the post-injection is performed after the exhaust temperature has risen to some extent, so that it waits for the exhaust temperature to rise.

  If post injection is being performed in step S3, it is determined whether or not the time (elapsed time) that has elapsed since the start of post injection is longer than the predetermined time t (step S4). The predetermined time t is an arrival determination time from the start of post-injection until reaching the oxidation catalyst 16, and the intake air amount is detected by the air flow sensor 28, and the exhaust flow rate calculated from the intake air amount and the fuel injection amount is It is calculated corresponding to a one-dimensional map stored in advance.

  In step S4, if the predetermined time t has passed since the start of post injection, it is determined whether or not the exhaust temperature before the DPF 3 is lower than the predetermined temperature T (step S5). This predetermined temperature T is a threshold value for determining the temperature rise of the DPF 3 and is the temperature at which PM is most likely to burn, and the amount of fuel post-injected by the injector 5 is calculated in correspondence with a one-dimensional map stored in advance. It is obtained by a method, a method of calculating the post-injected fuel amount and the calculated exhaust flow rate in correspondence with a two-dimensional map stored in advance.

If it is determined in step S5 that the temperature of the DPF 3 has not risen to the predetermined temperature T, it is determined whether or not the amount of oxygen supplied to the DPF 3 is less than the predetermined value M (step S6). The predetermined value M is a determination threshold value for the amount of oxygen supplied to the DPF 3, and the post-injected fuel amount is calculated in association with a one-dimensional map stored in advance.
In step S6, when the amount of oxygen supplied to the DPF 3 is less than the predetermined value M, the oxygen is excessively throttled, and therefore, the correction operation of the exhaust gas temperature raising device for raising the exhaust gas temperature is performed (step S6). S7). In Steps S1 to S6, if it is determined that the condition is not satisfied, all returns and the determination is started from Step S1.

  Thus, according to the present DPF regeneration control device, when the amount of oxygen supplied to the DPF 3 does not reach the predetermined value M, the exhaust temperature raising device is raised by correcting the exhaust temperature raising device. Therefore, the temperature rise failure of the DPF 3 due to excessive throttling of oxygen can be avoided. Therefore, the regeneration of the DPF 3 can be reliably performed, and wasteful post-injection can be avoided, so that oil dilution can be reduced.

Further, whether or not the amount of oxygen supplied to the DPF 3 is insufficient is determined when the temperature of the DPF 3 does not reach the predetermined temperature T even though the predetermined time t has elapsed since the start of the post injection. Since the determination is performed after the determination, the oxygen amount is determined only when necessary, and only the minimum necessary calculation is performed.
In particular, when regeneration of the DPF 3 is performed in an idle operation state including manual regeneration, it is necessary to more strictly and surely raise the DPF 3 by raising the exhaust gas temperature. Since the exhaust temperature can be raised by performing a correction operation on the device, the regeneration of the DPF 3 can be performed reliably.

  Further, the exhaust temperature raising device includes an oxygen amount adjusting device which is any one or more of an intake throttle, a fuel injection device, a variable displacement turbocharger, and an exhaust brake. The amount of oxygen supplied to the DPF can be ensured by correcting the oxygen amount adjusting device. Further, when any one of the oxygen amount adjusting devices is sufficient, the correction operation can be easily performed. When one of the oxygen amount adjusting devices cannot secure the oxygen amount, a plurality of combinations can be used to ensure the oxygen amount. The amount can be secured.

Further, since the exhaust temperature raising device includes one or both of the fuel injection device and the common rail, the exhaust temperature can be raised by performing a correction operation on these devices. Regeneration can be performed more reliably.
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.

1 Diesel engine (engine)
2 Variable capacity turbocharger (VG turbocharger)
3 Diesel particulate filter (DPF)
4 Air cleaner 5 Injector (fuel injection device)
6 EGR valve 7 Intake throttle 8 Exhaust brake 9 DPF cleaning switch 10 Intake passage 11 Exhaust passage 12 EGR passage 13 Cylinder 14 Piston 15 Connecting rod 16 Oxidation catalyst 17 Turbocharger actuator 18 Throttle valve actuator 19 EGR valve actuator 20 Exhaust brake use Actuator 21 Intake pressure sensor 22 Crank angle sensor 23 Accelerator opening sensor 24 Water temperature sensor 25 Common rail pressure sensor 26 Catalyst temperature sensor 27 Exhaust temperature sensor 28 Air flow sensor 30 Engine control device (engine ECU)
31 Oxygen supply control means 32 Temperature rise control means 33 Temperature determination means 34 Oxygen amount determination means 35 Device correction means 36 Fuel injection control means 37 Turbocharger control means 38 Intake throttle control means 39 Exhaust brake control means 40 Common rail pressure control means

Claims (4)

A DPF regeneration control device for regenerating the DPF by removing the PM from a filter (DPF) that collects particulate matter (PM) contained in exhaust gas from a diesel engine,
When the PM accumulates more than a predetermined value, temperature increase control means for suppressing the amount of oxygen in the exhaust and performing post injection to raise the temperature of the DPF to a predetermined temperature at which the PM can burn;
Oxygen supply control means for supplying oxygen to the DPF and burning the PM when the temperature of the DPF rises to the predetermined temperature by temperature increase control by the temperature increase control means,
The temperature raising control means includes
Temperature determination means for determining whether the temperature of the DPF has risen to the predetermined temperature after a predetermined time has elapsed since the start of the post-injection;
An oxygen amount determination means for determining whether the amount of oxygen supplied to the DPF is less than a predetermined value when it is determined by the temperature determination means that the temperature of the DPF has not risen to the predetermined temperature;
Device correcting means for correcting an exhaust temperature raising device for raising the exhaust temperature when the oxygen amount judging means judges that the amount of oxygen supplied to the DPF is less than a predetermined value. A DPF regeneration control device characterized by comprising: The DPF regeneration control device according to claim 1, wherein regeneration of the DPF is performed in an idle operation state including manual regeneration.   The exhaust temperature raising device includes an oxygen amount adjusting device which is any one or more of an intake throttle, a fuel injection device, a variable capacity turbocharger, and an exhaust brake. The DPF regeneration control device according to claim 1, wherein the DPF regeneration control device is characterized. The DPF regeneration control according to claim 3, wherein the exhaust temperature raising device includes one or both of the fuel injection device and a common rail for storing high-pressure fuel. apparatus.

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