JP2010180842A - Exhaust emission control device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device improving fuel economy in regeneration of a DPF and inhibiting deterioration of a battery. <P>SOLUTION: The exhaust emission control device 100 of an engine 10 includes the filter 32 collecting particulate matter in exhaust gas and burns the particulate matter accumulated in the filter 32 in filter regeneration by raising temperature of the exhaust gas. The exhaust emission control device includes a power generation device 11 driven by the engine 10 to generate electric power and supplying the electric power to the battery based on a target battery charging amount, and a charging amount control means S303 increasing the target battery charging amount in filter regeneration so that exhaust temperature rises with increase of a power generation load of the power generation device 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust purification device that purifies exhaust exhausted from an engine.

  Patent Document 1 discloses a diesel particulate filter (Diesel Particulate Filter; hereinafter referred to as “DPF”) that collects particulate matter (Particulate Matter; hereinafter referred to as “PM”) contained in the exhaust of a diesel engine and purifies the exhaust. ) Is disclosed. In this exhaust purification device, the DPF regeneration control for regenerating the DPF function is performed by raising the exhaust temperature when a predetermined amount of PM is deposited on the DPF and maintaining the DPF temperature at about 600 ° C. at which the PM starts to self-ignite. carry out.

JP 2005-90454 A

  The exhaust emission control device described in Patent Document 1 increases the engine load by increasing the power generation load of the alternator during DPF regeneration, and increases the fuel injection amount in the main fuel injection, thereby increasing the exhaust temperature.

  In order to increase the power generation load of the alternator, it is conceivable to forcibly operate the defogger or the like during DPF regeneration, but there is a possibility that the defogger or the like may be operated unnecessarily. This simply increases the fuel injection amount in order to raise the exhaust temperature, and the fuel consumption performance during DPF regeneration deteriorates.

  Moreover, if the electricity generated by the alternator is charged into the battery without considering the battery charge amount, the battery may be overcharged and deteriorated.

  Therefore, the present invention has been made paying attention to such problems, and an object of the present invention is to provide an exhaust emission control device that can improve fuel efficiency at the time of DPF regeneration and further suppress battery deterioration. To do.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.

  The present invention includes a filter (32) that collects particulate matter in exhaust gas, and exhaust purification of an engine (10) that burns particulate matter that has accumulated on the filter (32) by raising the exhaust temperature during filter regeneration. A power generation device (100) that is driven by the engine (10) to generate power and supplies power to the battery based on a target battery charge amount; and power generation of the power generation device (11) during filter regeneration Charge amount control means (S303) for increasing the target battery charge amount so that the exhaust temperature rises as the load increases.

  According to the present invention, when the filter is regenerated, the target battery charge amount is increased, and the power generation load of the power generation device is increased, so that the particulate matter deposited on the filter is burned by increasing the exhaust temperature while charging the battery. Since the engine load increases due to the increase in the power generation load of the power generation device, the fuel injection amount will be increased. However, since the battery is charged and the exhaust gas temperature is increased, the deterioration of fuel consumption performance during filter regeneration is suppressed Is possible. In addition, since the battery is charged based on the target battery charge amount, it is not overcharged and battery deterioration can be suppressed.

It is a schematic block diagram of the exhaust emission control device of the diesel engine for vehicles. It is a flowchart explaining the main routine for performing DPF regeneration control. It is a flowchart explaining the detail of DPF regeneration control. It is a timing chart explaining the change of PM deposition amount in DPF.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an exhaust emission control device 100 for a vehicle diesel engine.

  Referring to FIG. 1, the exhaust purification device 100 includes an engine 10, an intake passage 20 through which fresh air from the outside flows into the engine 10, an exhaust passage 30 through which exhaust from the engine 10 flows outside, and a controller 40. .

  An intake throttle valve 21 is provided in the intake passage 20.

  The intake throttle valve 21 adjusts the amount of intake air supplied to the engine 10 by changing the intake flow area of the intake passage 20. The intake air that has passed through the intake throttle valve 21 is distributed to each cylinder of the engine 10 via an intake collector.

  The engine 10 includes an alternator 11 and an injector 12.

  The alternator 11 is a generator that is driven by the rotation of the crankshaft to generate electric power. The alternator 11 supplies power to an electric load 51 such as a defogger or a headlight that is an electrical component, and charges the battery 52 so that the battery charge amount becomes a target value. The alternator 11 incorporates a voltage regulator, and the generated voltage is adjusted according to the state of the electric load 51 and the battery charge amount of the battery 52 by the voltage regulator.

  The battery 52 supplies the stored power to the electric load 51 according to the engine operating state.

  The injector 12 is provided so as to face the combustion chamber of each cylinder of the engine 10 and injects fuel into the combustion chamber. The injected fuel is combusted by intake air that has been highly compressed in the combustion chamber and has reached a high temperature. Exhaust gas generated by the combustion is discharged from the engine 10 to the exhaust passage 30.

  The exhaust passage 30 is provided with a NOx catalytic converter 31 and a DPF 32 in order from the upstream.

  The NOx catalytic converter 31 carries a NOx catalyst on a monolith carrier made of cordierite. The NOx catalyst of the NOx catalytic converter 31 captures NOx in exhaust when the exhaust air-fuel ratio is leaner than stoichiometric, and desorbs and reduces NOx when the exhaust air-fuel ratio is richer than stoichiometric.

  The DPF 32 is a porous honeycomb structure made of cordierite, and partitions the flow path through which exhaust gas flows in a lattice pattern by porous thin walls. The inlet of each flow path is alternately sealed, and the flow path in which the inlet is not sealed is sealed in the outlet. Therefore, when the PM contained in the exhaust gas flowing into the DPF 32 passes through the porous thin wall, Collected on the surface. Therefore, the DPF 32 collects PM contained in the exhaust discharged from the engine 10 and flows the exhaust from which the PM is removed downstream.

  The power generation load of the alternator and the fuel injection timing of the injector 12 are controlled by the controller 40.

  The controller 40 includes a microcomputer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface).

  The controller 40 includes a crank angle sensor 41 that detects the engine speed, an accelerator pedal sensor 42 that detects the amount of depression of the accelerator pedal, a water temperature sensor 43 that detects the temperature of cooling water that cools the engine 10, and a DPF 32 Detection data from a differential pressure sensor 44 that detects a difference between the inlet side exhaust pressure and the outlet side exhaust pressure is input as a signal.

  Based on these input signals, the controller 40 calculates the PM accumulation amount in the DPF 32 and performs regeneration control of the DPF 32. The DPF regeneration control is a control for regenerating the function of the DPF 32 by increasing the exhaust gas temperature when a predetermined amount of PM is deposited on the DPF 32 to burn the PM at a DPF temperature of 600 ° C. or higher.

  In the exhaust purification apparatus of the conventional method, the exhaust gas temperature is raised by increasing the power generation load of the alternator during DPF regeneration.

  However, for example, when the defogger or the like is forcibly activated during DPF regeneration to increase the power generation load of the alternator, the defogger or the like may be operated unnecessarily. In such a case, the fuel injection amount of the main fuel injection is simply increased in order to raise the exhaust temperature, and there is a problem that the fuel consumption performance at the time of DPF regeneration is deteriorated. In addition, when charging the battery with the electric power generated by the alternator without considering the battery charge amount, there is a problem that the battery is deteriorated due to overcharging.

  Therefore, the exhaust purification apparatus 100 reduces the target battery charge before DPF regeneration, then increases the target battery charge during DPF regeneration and increases the power generation load of the alternator 11, thereby charging the battery 52. Since the exhaust temperature is raised and PM is burned and removed, both improvement in fuel efficiency during regeneration of the DPF and suppression of battery deterioration are achieved.

  Control executed by the controller 40 to regenerate the DPF 32 will be described with reference to FIGS. 2 and 3.

  FIG. 2 is a flowchart for explaining a main routine executed by the controller 40. The main routine is repeatedly executed at regular intervals, for example, 10 ms during operation of the engine 10.

  In step S101, the controller 40 determines the presence or absence of water temperature characteristic abnormality or battery deterioration.

  When there is no water temperature characteristic abnormality or battery deterioration, the controller 40 executes the process of step S102. On the other hand, when there is a water temperature characteristic abnormality or battery deterioration, the controller 40 ends the process.

  When the thermostat breaks down or clogging occurs in the cooling water passage, the cooling water temperature becomes high. If the exhaust temperature is raised for DPF regeneration in such a state, the engine 10 may be overheated. Therefore, when there is an abnormality in the water temperature characteristic, the regeneration of the DPF 32 is not performed. In addition, when the cooling water temperature detected by the water temperature sensor 43 is higher than a predetermined temperature, it is determined that there is a water temperature characteristic abnormality.

  Further, when the battery 52 is deteriorated, the battery may run out depending on the electric load 51 and the use state of the auxiliary machinery. Therefore, when there is battery deterioration, the regeneration of the DPF 32 is not performed. It is determined that the battery 52 is deteriorated when the degree of decrease in battery voltage during cranking at the time of engine start is small.

  In step 102, the controller 40 determines whether or not the DPF regeneration flag F is “1”.

  The controller 40 executes the process of step S103 when the DPF regeneration flag F is set to 1, and executes the process of step S104 when the DPF regeneration flag F is set to 0.

  In step S103, the controller 40 executes DPF regeneration control and ends the process. Details of the DPF regeneration control will be described later with reference to FIG.

  In step S104, the controller 40 determines whether or not the PM accumulation amount in the DPF 32 is larger than the predetermined accumulation amount PM1.

  The PM accumulation amount is calculated based on the detection value of the differential pressure sensor 44. The PM accumulation amount may be calculated by integrating the PM amount obtained from the detection value of the crank angle sensor 41 and the detection value of the accelerator pedal sensor 42.

  The controller 40 executes the process of step S105 when the PM accumulation amount is larger than the predetermined accumulation amount PM1, and ends the process otherwise.

  In step S105, the controller 40 determines whether or not the PM accumulation amount is larger than the predetermined accumulation amount PM2. The predetermined accumulation amount PM2 is a value larger than the predetermined accumulation amount PM1 in step S104, and is a limit value of the PM accumulation amount that requires the PM to be forcibly burned.

  The controller 40 executes the process of step S106 when the PM accumulation amount is smaller than the predetermined accumulation amount PM2, and otherwise executes the process of step S107.

  In step S106, the controller 40 reduces the target battery charge amount of the battery 52 from the predetermined charge amount SOC1 to the predetermined charge amount SOC2, and ends the process.

  During normal operation in which the PM accumulation amount is smaller than the predetermined accumulation amount PM1, the target battery charge amount of the battery 52 is set to a predetermined charge amount SOC1 that is larger than the predetermined charge amount SOC2. When the PM accumulation amount becomes larger than the predetermined accumulation amount PM1 and the target battery charge amount decreases to the predetermined charge amount SOC2 in step S106, the battery 52 is discharged and supplies electric power to the electric load 51. Therefore, before the DPF regeneration, the actual battery charge amount of the battery 52 is reduced to the predetermined charge amount SOC2.

  In step S107, the controller 40 sets the DPF regeneration flag F to 1 and ends the process.

  FIG. 3 is a flowchart for explaining a subroutine of DPF regeneration control.

  In step S301, the controller 40 determines whether or not the engine 10 is operating at a low engine speed and a low engine load based on the detection value of the crank angle sensor 41 and the detection value of the accelerator pedal sensor 42.

  When the engine 10 is operating at a low engine speed and a low engine load, the controller 40 executes the processes of steps S302 to S303 to increase the exhaust temperature. On the other hand, when the engine 10 is operating at a high engine rotation speed or a high engine load, the controller 40 executes the processes of steps S307 to S309 to increase the exhaust temperature.

  In step S302, the controller 40 controls the injector 12 to perform post fuel injection.

  The post fuel injection is fuel injection performed after the main fuel injection in order to raise the exhaust gas temperature separately from the main fuel injection that contributes to the engine output.

  In step S303, the controller 40 sets the target battery charge amount of the battery 52 to a predetermined charge amount SOC1.

  When the target battery charge amount of the battery 52 increases from the predetermined charge amount SOC2 to the predetermined charge amount SOC1, the alternator 11 starts charging the battery 52 so that the actual battery charge amount becomes the predetermined charge amount SOC1. When the target battery charge amount is controlled to increase in this way and the power generation load of the alternator 11 is increased, the fuel injection amount of the main fuel injection increases, so that the exhaust temperature rises.

  When the engine speed is low and the engine load is low, the temperature of the exhaust gas immediately after the engine is discharged is relatively low. Therefore, post fuel injection is performed as in steps S302 and S303, and the target battery charge amount is increased to generate power from the alternator 11. The exhaust temperature is increased by increasing the load. By raising the exhaust gas temperature in this way, PM deposited on the DPF 32 is removed by combustion.

  In step S304, the controller 40 determines whether or not the PM accumulation amount is smaller than the predetermined accumulation amount PM3. The predetermined accumulation amount PM3 is a value smaller than the predetermined accumulation amount PM1 and a value close to zero.

  When the PM accumulation amount is smaller than the predetermined accumulation amount PM3, the controller 40 determines that the DPF 32 has been regenerated, and performs the process of step S305. On the other hand, when the PM accumulation amount is larger than the predetermined accumulation amount PM3, the controller 40 determines that it is necessary to continue the regeneration of the DPF 32, and ends the processing.

  In step S305, the controller 40 sets the DPF regeneration flag F to 0, and performs the process of step S306.

  In step S306, the controller 40 stops the exhaust gas temperature increase control for DPF regeneration, sets the target battery charge amount to the predetermined charge amount SOC1, and causes the engine 10 to operate normally.

  On the other hand, when the engine 10 is operating at a high engine speed or a high engine load, in step S307, the controller 40 sets the target battery charge amount to the predetermined charge amount SOC2. Thereby, the actual battery charge amount of battery 52 is reduced to a predetermined charge amount SOC2.

  In step S308, the controller 40 controls the delay of the main fuel injection timing, and performs the process of step S304.

  When the engine 10 is operating at a high engine speed or a high engine load, the exhaust temperature immediately after engine discharge is relatively high, so that the main fuel injection timing is retarded without increasing the fuel injection amount. Thus, the exhaust temperature can be raised to the DPF regeneration.

  Next, with reference to FIG. 4, the change in the PM accumulation amount of the DPF 32 of the exhaust purification apparatus 100 will be described. FIG. 4 is a timing chart showing changes in the amount of PM deposited on the DPF 32.

  As shown in FIG. 4A, the PM accumulation amount in the DPF 32 increases during normal engine operation.

  When the PM accumulation amount exceeds the predetermined accumulation amount PM1 at time t1, the target battery charge amount is lowered to the predetermined charge amount SOC2 as shown in FIG. Then, as shown in FIG. 4E, the generated voltage value of the alternator 11 is suppressed, and the battery 52 is discharged to supply power to the electric load 51. Thereby, the actual battery charge amount of battery 52 is reduced to a predetermined charge amount SOC2.

  When the PM accumulation amount exceeds the predetermined accumulation amount PM2 at time t2, DPF regeneration control is started.

  Between time t2 and t3, as shown in FIG. 4B, the engine is in a high engine load state, so PM is burned by retarding the main fuel injection and raising the exhaust gas temperature. Therefore, as shown in FIG. 4A, the PM accumulation amount starts to decrease from time t2.

  From time t3 to time t4, when the engine 10 is operated at a low engine speed and a low engine load, post fuel injection for raising the exhaust temperature is performed as shown in FIG. Further, since the target battery charge amount is increased to the predetermined charge amount SOC1 as shown in FIG. 4 (D), the power generation voltage value of the alternator 11 is increased as shown in FIG. 4 (E). Alternator 11 starts charging battery 52 so that the actual battery charge amount becomes predetermined charge amount SOC1. When the power generation load of the alternator 11 increases in this way, the engine load increases and the main fuel injection amount increases as shown by the arrow in FIG. 4B, so that the exhaust temperature rises.

  In the exhaust emission control device 100, the power generation load of the alternator 11 is increased simultaneously with the post fuel injection to raise the exhaust temperature. Therefore, even if the post fuel injection amount is suppressed as shown by the arrow in FIG. It can be raised to possible exhaust temperatures.

  As described above, from time t3 to time t4, post fuel injection is performed and the power generation load of the alternator 11 is increased to raise the exhaust gas temperature, whereby PM accumulated in the DPF 32 is removed by combustion.

  When the engine load is again high at time t4, PM is burned by retarding the main fuel injection and raising the exhaust gas temperature. When the PM accumulation amount becomes smaller than the predetermined accumulation amount PM at time t5 and the DPF regeneration control ends, the engine 10 starts normal operation.

  As described above, in the exhaust purification device 100 of the present embodiment, the following effects can be obtained.

  In the exhaust emission control device 100, the target battery charge amount that has been reduced to the predetermined charge amount SOC2 before the DPF regeneration is increased to the predetermined charge amount SOC1 during the DPF regeneration, and the power generation load of the alternator 11 is increased to charge the battery 52. However, the PM accumulated in the DPF 32 is burned by raising the exhaust temperature. Since the engine load increases due to the increase in the power generation load of the alternator 11, the fuel injection amount is increased. However, since both the charging of the battery 52 and the exhaust gas temperature increase are performed, the deterioration of the fuel consumption performance during filter regeneration is suppressed. It becomes possible. In addition, since the battery 52 is charged based on the target battery charge amount, overcharge is not caused, and battery deterioration can be suppressed.

  Since the exhaust purification apparatus 100 is configured to increase the target battery charge amount simultaneously with the execution of the post fuel injection control, the post fuel injection amount can be reduced as compared with the case where the exhaust gas temperature is raised only by the post fuel injection control. it can. As a result, the exhaust gas temperature can be quickly raised while improving the fuel efficiency during DPF regeneration.

  Note that the present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

100 Exhaust purification device 10 Engine 11 Alternator (power generation device)
12 Injector 30 Exhaust passage 32 Diesel particulate filter (filter)
40 Controller 41 Crank angle sensor 42 Accelerator pedal sensor 43 Water temperature sensor 44 Differential pressure sensor 51 Electric load 52 Battery S106, S303 Charge control means S302 Fuel injection control means

Claims (3)

An exhaust purification device for an engine, comprising a filter that collects particulate matter in exhaust gas, burns particulate matter deposited on the filter by raising the exhaust temperature during filter regeneration,
A power generator that is driven by an engine to generate power and supplies power to the battery based on a target battery charge amount;
A charge amount control means for increasing the target battery charge amount so that the exhaust temperature rises due to an increase in the power generation load of the power generation device during the filter regeneration;
An exhaust emission control device for an engine comprising: The charge amount control means decreases the target battery charge amount before filter regeneration, and increases the target battery charge amount during filter regeneration.
The engine exhaust gas purification apparatus according to claim 1. Fuel injection control means for injecting post fuel after main fuel injection so that the exhaust temperature rises during the regeneration of the filter,
The charge amount control means increases the target battery charge amount during post fuel injection control.
The exhaust emission control device for an engine according to claim 1 or 2, characterized in that

Images