JP5110327B2 - Engine exhaust purification system - Google Patents

Description

  The present invention relates to an exhaust emission control device for an engine, and more particularly to a regeneration technology for an exhaust emission purification device provided in an exhaust passage.

  In general, an exhaust gas purifying apparatus that collects substances such as NOx (nitrogen oxide) and PM (particulate matter) in exhaust gas and purifies the exhaust gas is provided in the exhaust passage of the engine. In these exhaust gas purification apparatuses, by collecting substances in the exhaust gas, the components are accumulated in the exhaust gas purification apparatus, and the collection ability is gradually reduced. Therefore, regeneration processing is performed to remove components accumulated in the exhaust purification device by raising the temperature of the exhaust purification device. As a regeneration process, for example, a method has been developed in which the load of a generator driven by the engine is increased to cause the engine to operate at a high load, thereby increasing the temperature of the exhaust gas flowing into the exhaust purification device (Patent Document). 1).

JP 2007-230409 A

  In the above-mentioned patent document 1, electric energy generated by operating a generator is charged in a battery and used later. Furthermore, by reducing the amount of charge of the battery in advance before the regeneration process, overcharging of the battery is prevented. Therefore, in Patent Document 1, in order to secure the reproduction time, there is a case where the amount of charge of the battery needs to be greatly reduced in advance before the reproduction, especially when the battery capacity is small, like a starter motor. Considering the operable time of an on-vehicle device that consumes a large amount of power, it is not preferable to significantly reduce the charge amount of the battery.

  The present invention has been made to solve such problems, and the object of the present invention is to prevent the battery from being overcharged during reproduction and to prevent a significant drop in the state of charge. An object of the present invention is to provide an engine exhaust gas purification device that can be appropriately maintained.

In order to achieve the above object, the invention of claim 1 is directed to an electric generator driven by an engine to generate electric power with variable power generation and charge a battery, and an exhaust gas purification provided in an exhaust passage of the engine to purify exhaust gas. And a regeneration means for regenerating the exhaust purification means by applying a load to the engine by power generation by the generator and increasing the output torque of the engine to increase the temperature of the exhaust gas flowing into the exhaust purification means. The exhaust emission control device includes a charge state detecting means for detecting a chargeable capacity of the battery and a remaining regeneration time calculating means for calculating a remaining regeneration time by the regeneration means. The regeneration means is configured to generate the maximum power of the generator during regeneration. Subtract the vehicle current consumption from the current to calculate the current that can be applied to the generator, and regenerate the chargeable capacity of the battery detected by the charge state detection means Divide by the remaining regeneration time calculated by the time calculation means to calculate the allowable generation current, and if the allowable generation current is lower than the applicable current, set the allowable generation current as the power generation amount of the generator and apply When the current is lower than the power generation allowable current, the applicable current is set as the power generation amount of the generator .

Further, the invention of claim 2 comprises, in claim 1 , temperature detection means for detecting the temperature of the exhaust purification means, and the regeneration means has a temperature of the exhaust purification means detected by the temperature detection means equal to or higher than a first predetermined value. If the temperature of the exhaust gas purifying means detected by the temperature detecting means is lower than the first predetermined value, the power generation amount of the generator is reduced to reduce the load of the engine. It is characterized by increasing the engine load by increasing the amount of power generation.

Further, the invention of claim 3, in claim 1 or 2, reproducing means, when changing the amount of electric power generated by the generator based on the charge state of the battery during playback, the output torque of the power generation amount and the engine It is characterized by being gradually changed.
According to a fourth aspect of the present invention, in any one of the first to third aspects, when the chargeable capacity of the battery detected by the charge state detecting means is less than the second predetermined value, It is further characterized by further comprising a regeneration preparation means for reducing the power generation amount of the generator in advance before regeneration so that the chargeable capacity increases to the second predetermined value.

The invention according to claim 5 provides the method according to any one of claims 1 to 4 , wherein the exhaust purification means is a nitrogen oxide storage catalyst for storing nitrogen oxide in the exhaust, and the regeneration means is a nitrogen oxide storage catalyst. The nitrogen oxide storage catalyst is regenerated by removing the sulfur oxide deposited on the catalyst.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the engine is a hybrid engine including a motor as a drive source, and the generator is a motor.

According to the engine exhaust gas purification apparatus of the first aspect of the present invention, it is easy to variably control the power generation amount of the generator during regeneration of the exhaust gas purification means to apply a load to the engine and increase the output torque of the engine. The regeneration can be performed by raising the exhaust temperature.
In particular, in the present application, the rechargeable capacity of the battery is detected during regeneration, the power generation allowable current is calculated by dividing the rechargeable capacity of the battery by the remaining regeneration time, and the vehicle current consumption is calculated from the maximum generated current of the generator. Is subtracted to calculate the current that can be applied to the generator. When the generation allowable current is lower than the applicable current, the generation allowable current is set as the power generation amount of the generator, so that the power generation amount of the generator decreases as the battery charge state approaches the fully charged state. It is possible to prevent overcharging of the battery during reproduction. In addition, since the battery is fully charged when the regeneration is completed, it is possible to perform the regeneration in a state where the charged state of the battery is as close as possible to the full charge while preventing the overcharge while securing the regeneration time.

  Therefore, the state of charge of the battery can be appropriately maintained so that the battery can be prevented from being overcharged or greatly reduced in the state of charge during regeneration. In particular, since a decrease in the amount of charge of the battery during reproduction is suppressed, it is possible to sufficiently ensure the operation time of an in-vehicle device or the like driven by the battery.

In addition, when the current that can be applied by the generator is lower than the allowable generation current, the current that can be applied is set to the amount of power generated by the generator. Torque can be accurately controlled according to the load of the generator.
According to the engine exhaust gas purification apparatus of claim 2 of the present invention, when the temperature of the exhaust gas purification means is equal to or higher than the first predetermined value, the power generation amount of the generator is reduced and the engine load is reduced. The exhaust temperature decreases. On the other hand, when the temperature of the exhaust gas purification means is less than the first predetermined value, the power generation amount of the generator is increased and the engine load is increased, so that the exhaust gas temperature rises. In this way, the exhaust gas temperature is corrected according to the temperature of the exhaust gas purification means, and the exhaust gas purification means can be regenerated more appropriately.

According to the engine exhaust gas purification apparatus of the third aspect of the present invention, when the power generation amount of the generator is changed, the power generation amount and the engine output torque are gradually changed. Therefore, the engine operation during regeneration can be stabilized.
According to the exhaust emission control device for an engine of claim 4 of the present invention, when the chargeable capacity of the battery is smaller than the second predetermined value, the power generation amount is reduced before regeneration to reduce the chargeable capacity of the battery to the second value. Therefore, it is difficult to overcharge and more regeneration opportunities can be secured.

According to the engine exhaust gas purification apparatus of the fifth aspect of the present invention, during the so-called S purge for removing sulfur oxide deposited on the nitrogen oxide storage catalyst, the state of charge of the battery is detected and the power generation amount of the generator is determined. By controlling, the state of charge of the battery can be appropriately maintained.
According to the engine exhaust gas purification apparatus of claim 6 of the present invention, in a hybrid engine, a motor having a function of a generator is used to detect the state of charge of the battery during regeneration of the exhaust gas purification means, and the amount of power generated by the motor. By controlling this, it is possible to appropriately maintain the state of charge of the battery.

It is a schematic block diagram of the exhaust system of the engine which concerns on this invention. It is a flowchart which shows the control point of S purge. It is a flowchart which shows the subroutine of a generator load control process. It is a map which calculates | requires a generated current maximum value. It is a graph which shows the breakdown of the load torque of an alternator. It is a map for S purge determination. It is a map for correction | amendment according to a catalyst temperature. It is a flowchart which shows the preparation control of the charge condition of the battery before reproduction | regeneration control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an exhaust system of an engine 1 to which an exhaust emission control device of the present invention is applied.
The engine 1 of this embodiment is a diesel engine. In the exhaust passage 2 of the engine 1, an oxidation catalyst (DOC) 3, a NOx storage catalyst (NTC) 4, and a DPF (diesel particulate filter) 5 are disposed in order from the engine 1 toward the downstream side as exhaust purification means. It is disguised. The oxidation catalyst 3 is formed by supporting a catalytic noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh) on a porous wall forming a passage, and oxidizes CO and HC in exhaust gas. together is converted to CO ₂ and _{H 2} O Te has a function of NO in the exhaust is oxidized to generate NO _2.

  The NOx storage catalyst 4 is configured, for example, by supporting a NOx storage agent such as barium (Ba) or potassium (K) on a support containing a noble metal such as platinum (Pt) or palladium (Pd). While trapping NOx under an air-fuel ratio atmosphere (oxidizing atmosphere), it has the function of releasing the trapped NOx under a rich air-fuel ratio atmosphere (reducing atmosphere) and reducing it by reacting with HC and CO in the exhaust. is doing.

The DPF 5 has a function of, for example, alternately closing the upstream side and the downstream side of the honeycomb carrier passage with plugs to collect PM in the exhaust gas, and further, on the porous wall forming the passage. It is formed by supporting a catalytic noble metal such as platinum (Pt), palladium (Pd), rhodium (Rh).
The starter motor 10 of the engine 1 is driven by power supplied from the battery 11. The battery 11 is supplied with electric power from an alternator (generator) 12 driven by the engine 1 to be charged. The alternator 12 is drive-controlled by the ECU 20 and has a function capable of changing the amount of power generation.

A line connecting the battery 11 and the alternator 12 is provided with a current sensor 21 that detects a current value Ib for charging / discharging the battery 11.
A temperature sensor 22 is provided in the exhaust passage 2 upstream of the NOx storage catalyst 4 to detect the temperature of the exhaust gas flowing into the NOx storage catalyst 4 as the catalyst temperature Tc.
The ECU 20 is a control device for performing comprehensive control including operation control of the engine 1, and includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and the like. It consists of

A crank angle sensor that detects a crank angle, an airflow sensor (not shown), an accelerator position sensor, and the like are connected to the input side of the ECU 20, and detection information from these sensors is input.
On the other hand, various output devices such as a fuel injection valve and a throttle valve are connected to the output side of the ECU 20. The ECU 20 calculates the fuel injection amount, the fuel injection timing, the intake air amount, etc. into the cylinder based on the detection information from various sensors, and outputs them to various output devices, respectively, so that the fuel injection valve etc. at an appropriate timing To control.

By disposing the oxidation catalyst 3 upstream of the DPF 5 as described above, NO ₂ is discharged from the oxidation catalyst 3 in a rich air-fuel ratio atmosphere, passes through the NOx storage catalyst 4, flows into the DPF 5, and is captured by the DPF 5. It reacts with soot, which is a carbon component in the accumulated PM, and oxidizes it. The oxidized soot becomes CO _{2 and} is removed from the DPF ₅ , and the DPF 5 is continuously regenerated (continuous regeneration).

  In the above-described continuous regeneration, the DPF 5 may not be sufficiently regenerated depending on the operating condition of the engine 1. Therefore, the ECU 20 estimates the amount of PM accumulated in the DPF 5, and performs forced regeneration when the estimated amount exceeds an allowable amount. In the forced regeneration, the temperature of the exhaust gas flowing into the DPF 5 is raised to burn and remove the PM deposited on the DPF 5 to regenerate the DPF 5 (regeneration means).

For example, the forced regeneration start determination is performed by integrating the fuel injection amount into the cylinder and the operating time of the engine 1 or by detecting the differential pressure in the exhaust passage between the upstream side and the downstream side of the DPF 5. Or a determination based on the integrated value of the exhaust flow rate.
Further, the engine 1 is provided with a NOx purge function for discharging NOx stored in the NOx storage catalyst 4. The NOx purge is executed by the ECU 20 by enriching the air-fuel ratio of the exhaust gas flowing into the NOx storage catalyst 4 as described above based on the detection information from the various sensors described above, that is, the operating state of the engine 1. The Further, since SOx resulting from oxidation of the sulfur component in the fuel is also deposited as sulfate on the NOx storage catalyst 4, the engine 1 has S (sulfur) to remove the accumulated sulfur component from the NOx storage catalyst 4. A purge function is also provided. This S purge is executed by enriching the air-fuel ratio of the exhaust gas flowing into the NOx storage catalyst 4 and raising the exhaust temperature to bring the NOx storage catalyst 4 to a high temperature state, similarly to the NOx purge. . The start determination of NOx purge and S purge may be estimated by integrating the amount of fuel injected into the cylinder and the operating time of the engine 1, for example.

  During regeneration such as forced regeneration or S purge, in the present embodiment, a method of increasing the torque by increasing the fuel injection amount from the fuel injection valve is employed as a method of increasing the exhaust temperature. In particular, in the present embodiment, the ECU 20 inputs the current state Ib of the battery 11 input from the current sensor 21, the catalyst temperature Tc input from the temperature sensor 22, the operating state of the engine 1 such as the rotational speed Ne of the engine 1, and the regeneration. At this time, the load of the alternator 12 and the torque control of the engine 1 are controlled according to the state of charge of the battery 11.

Hereinafter, S purge control of the NOx occlusion catalyst 4 will be described as one of regeneration control of the exhaust gas purification apparatus with reference to FIGS.
FIG. 2 is a flowchart showing a control determination procedure at the time of S purge in the ECU 20.
This routine is executed when the key switch is turned ON.
In step S10, the state of charge of the battery 11 is monitored. Specifically, the current value Ib for charging / discharging the battery 11 detected by the current sensor 21 is input. Then, the process proceeds to step S20.

  In step S20, the remaining capacity (chargeable capacity) Qb of the battery 11 is calculated as a numerical value indicating the state of charge of the battery 11 (charge state detection means). The remaining capacity Qb of the battery is obtained by integrating the current value Ib input in step S10. As a numerical value indicating the state of charge, the remaining capacity Qb (AH) represented by current × time is used in this embodiment. Instead of the remaining capacity Qb, SOC (%) indicating the ratio of the charged amount to the full charge is used. May be used. Then, the process proceeds to step S30.

  In step S30, it is determined whether or not the NOx storage catalyst 4 requires S purge. Whether or not S purge is necessary is determined by, for example, integrating the fuel injection amount into the cylinder of the engine 1 and the operating time of the engine 1 and determining whether or not the integrated value exceeds a preset allowable amount. That's fine. If S purge is not required, this routine is terminated. If S purge is required, the process proceeds to step S40.

  In step S40, it is determined whether or not the remaining capacity Qb of the battery 11 calculated in step S20 is greater than a predetermined value Q1. When the remaining capacity Qb is larger than the predetermined value Q1, the generator load control subroutine S50 is executed. The predetermined value Q1 may be set to a value close to full charge so that it can be determined whether or not the battery 11 needs to be charged during the S purge. Then, when the generator load control subroutine S50 ends, this (main) routine also ends.

If it is determined in step S40 that the remaining capacity Qb is equal to or less than the predetermined value Q1, that is, close to full charge, the process proceeds to step S60.
In step S60, it is determined whether normal S purge is possible. The normal S purge is an S purge that is executed without increasing the load of the alternator 12 so that the battery 11 is not charged. Specifically, it is determined whether or not the operating state of the engine 1 is a high-load operating state without applying a load by the alternator 12 and S purge is possible. If the normal S purge is possible, the process proceeds to step S70.

In step S70, normal S purge is performed. The normal S purge is control for increasing the exhaust temperature by increasing the torque generated by the engine 1 without increasing the load of the alternator 12 as described above. Then, this routine ends.
If it is determined in step S60 that the normal S purge is not possible, the process proceeds to step S80.

In step S80, normal engine control is continued without performing S purge. Then, this routine ends.
FIG. 3 is a flowchart showing a subroutine of the generator load control process executed in step S50 of the main routine.
When this subroutine is started, first, in step S100, the current value Ib detected by the current sensor 21 is input. Then, the process proceeds to step S110.

In step S110, the current value Ib input in step S100 is integrated to calculate the remaining capacity Qb of the battery 11. Then, the process proceeds to step S120.
In step S120, it is determined whether or not the remaining capacity Qb of the battery 11 calculated in step S110 is greater than a predetermined value Q1, that is, whether or not the battery 11 is not in a fully charged state. If the remaining capacity Qb is equal to or less than the predetermined value Q1, that is, close to full charge, this subroutine is terminated and the process returns to the main routine. When the remaining capacity Qb is larger than the predetermined value Q1, that is, when the state is not close to full charge, the process proceeds to step S130.

In step S130, the power generation allowable current α of the alternator 12 is calculated by the following equation (1) using the remaining battery capacity Qb calculated in step S110 and an S purge remaining time Tr described later in step S250.
α = Qb / Tr (1)
Then, the process proceeds to step S140.

In step S140, the current Ib flowing into and out of the battery 11 is detected and input by the current sensor 21, and based on the current value Ib currently flowing into the battery 11 and the currently set power generation current value Ig of the alternator 12. Then, the current vehicle consumption current Iw is calculated by the following equation (2).
Iw = Ig−Ib (2)
Then, the process proceeds to step S150.

In step S150, the generated current value Igmax when the alternator 12 is in full operation according to the current engine speed Ne is obtained using FIG. Based on the generated current value Igmax and the vehicle consumption current Iw calculated in step S140, a current β (applicable current) that can be applied by the alternator 12 is calculated by the following equation (3).
β = Igmax−Iw (3)
Then, the process proceeds to step S160.

In step S160, the power generation allowable current α calculated in step S130 is compared with the applicable current β calculated in step S150, the smaller one of the two values α and β is selected, and the alternator 12 is selected. To the generated current target value Ig. Then, the process proceeds to step S170.
In step S170, the load torque Lb corresponding to the load application of the alternator 12 is calculated based on the generated current target value Ig of the alternator 12 set in step S160 and the vehicle consumption current Iw calculated in step S140. Specifically, as shown in Expression (4), the load of the alternator 12 for generating the vehicle consumption current Iw from the load torque La of the alternator 12 necessary for generating the generation current target value Ig set in step S160. The torque Lw is subtracted, and the load torque Lb corresponding to the load applied by the alternator 12 is calculated.

Lb = La−Lw (4)
Then, the process proceeds to step S180. FIG. 5 is a graph showing a breakdown of the load torque La of the alternator 12. As shown in FIG. 5, each value changes according to the rotational speed Ne of the engine 1, but the load torque La corresponding to the generated current target value Ig of the alternator 12 is the load torque Lw corresponding to the vehicle consumption current Iw. This is a value obtained by adding the load torque Lb applied by the alternator 12.

  In step S180, it is determined whether or not S purge is possible with the load La at the generated current target value Ig set in step S160. Whether or not S purge is possible is determined based on the rotational speed Ne of the engine 1 and the engine generated torque (load) as shown in FIG. It is determined that the S purge is not possible on the low load and low rotation side from the line indicating the threshold for S purge determination in FIG. 6, and the S purge is possible on the high rotation and high load side. For example, the load torque Lb is added by receiving the load even when the load is not applied by the alternator 12 (the shaded area in FIG. 6) and the load is lower than the line indicating the threshold value for S purge determination, even on the low rotation side. In this state (dot portion in FIG. 6), it is determined that S purge is possible if the load is higher than the line indicating the threshold value for S purge determination and the rotation speed is higher. If it is determined that the S purge is not possible, this subroutine is terminated and the process returns to the main routine. If it is determined that S purge is possible, the process proceeds to step S190.

  In step S190, the alternator 12 is controlled to generate the generated current target value Ig calculated in step S160. Further, for example, the fuel injection valve is controlled according to the load torque Lb calculated in step S170 to enrich the air-fuel ratio, and the generated torque of the engine 1 is increased. At this time, it is preferable to gradually increase the load of the alternator 12 and gradually increase the torque generated by the engine 1 so that the operation of the engine 1 does not become unstable. Then, the process proceeds to step S200.

In step S200, the exhaust temperature detected by the temperature sensor 22 is input as the catalyst temperature Tc of the NOx storage catalyst 4. The catalyst temperature Tc may be estimated from the operating state of the engine 1. Then, the process proceeds to step S210.
In step S210, it is determined whether or not the catalyst temperature Tc input in step S200 is equal to or higher than a target value T1 (first predetermined value). The target value T1 may be set to a temperature at which S purge is sufficiently possible. If the catalyst temperature Tc is equal to or higher than the target value T1, the process proceeds to step S220.

  In step S220, the generated current target value Ig of the alternator 12 is reduced to reduce the load on the alternator 12. Specifically, the correction amount ΔIg may be obtained from the catalyst temperature Tc and the engine rotational speed Ne using a map as shown in FIG. 7 and subtracted from the generated current target value Ig of the alternator 12 for correction. Further, the generated torque of the engine 1 is reduced by the amount of decrease in the load of the alternator 12. Then, the process proceeds to step S240.

If the catalyst temperature Tc is less than the target value T1 in step S210, the process proceeds to step S230.
In step S230, the load of the alternator 12 is increased by controlling the generated current target value Ig of the alternator 12 to increase. Specifically, the correction amount ΔIg obtained using FIG. 7 may be added to the generated current target value Ig of the alternator 12 for correction. Further, the generated torque of the engine 1 is increased by the increase in the load of the alternator 12. Then, the process proceeds to step S240.

  In step S240, it is determined whether or not the elapsed time Ts from the start of the S purge is within the set time T2. The set time T2 is set in advance to a time during which the sulfur component is removed from the NOx storage catalyst 4. When the elapsed time Ts exceeds the set time T2, the subroutine is terminated and the process returns to the main routine. If the elapsed time Ts is within the set time T2, the process proceeds to step S250.

In step S250, the S purge elapsed time Ts is subtracted from the S purge set time T2 to calculate the remaining S purge time Tr (regeneration remaining time calculating means). Then, the process returns to step S100.
Further, before the regeneration control, the ECU 20 performs battery charge preparation control for appropriately preparing the state of charge of the battery 11 (regeneration preparation means).

FIG. 8 is a flowchart showing preparatory control for the state of charge of the battery 11 before regeneration control.
In step S300, it is determined whether or not S purge is necessary in the near future. Whether or not the S purge is necessary in the near future may be determined based on whether or not the integrated value of the fuel injection amount into the cylinder of the engine 1 and the operating time of the engine 1 has approached the threshold value for starting the S purge. If S purge is necessary in the near future, the process proceeds to step S310.

In step S310, as in step S20, the remaining capacity Qb indicating the state of charge of the battery 11 is obtained, and it is determined whether or not the remaining capacity Qb is equal to or greater than a predetermined amount Q2 (second predetermined value). The predetermined amount Q2 is preferably set so that a capacity margin of the battery 11 can be secured. If the remaining capacity Qb is greater than or equal to the predetermined amount Q2, the process proceeds to step S320.
In step S320, the state in which the battery 11 is discharged by a predetermined amount Q2 or more is maintained. Then, this routine ends.

If it is determined in step S310 that the remaining capacity Qb is not equal to or greater than the predetermined amount Q2, the process proceeds to step S330.
In step S330, it is determined whether or not it is in a state where power generation can be suppressed, for example, whether or not an electric load with relatively large current consumption such as a headlamp is not operating, such as at night. If power generation can be suppressed, the process proceeds to step S340.

In step S340, the power generation amount of the alternator 12 is suppressed, the charge amount of the battery 11 is reduced, and a predetermined amount Q2 is discharged. Then, this routine ends.
If it is determined in step S330 that power generation cannot be suppressed, the process proceeds to step S350.
In step S350, it is determined whether or not it is necessary to prioritize S purge. Specifically, it is necessary to perform S purge even if there is a negative effect due to power generation suppression. Specifically, even if the amount of sulfur components deposited reaches a limit, and power generation suppression causes a decrease in headlamp illuminance, for example. It is determined whether or not it is necessary to perform S purge. If it is necessary to perform S purge, the process proceeds to step S360.

In step S360, the power generation amount of the alternator 12 is suppressed, the charge amount of the battery 11 is reduced, and a predetermined amount Q2 is discharged. Then, this routine ends.
If it is determined in step S350 that it is not necessary to prioritize S purge, the process proceeds to step S370.
In step S370, normal engine control is continued without suppressing power generation. Then, this routine ends.

By controlling as described above, during the S purge of the NOx storage catalyst 4, the generated current target value Ig of the alternator 12 is variably controlled to apply a load to the engine 1 and increase the output torque of the engine 1. Regeneration is performed by raising the exhaust temperature.
In particular, in the present embodiment, the remaining capacity Qb is detected as the state of charge of the battery 11 during the S purge, and it is determined whether or not the state is nearly full (predetermined value Q1 or less). In a state close to full charge, normal S purge in which no load is applied to the alternator 12 is performed. If the battery 11 is not fully charged and there is room for charging, the generation allowable current α, which is the current value at which the battery 11 is fully charged by charging the remaining S purge time Tr, is set as the target value for the generator current of the alternator 12. Set to Ig. As described above, the generated current target value Ig is variably controlled based on the state of charge of the battery 11, so that the state of charge of the battery 11 can be maintained within an appropriate range during the S purge. Specifically, since the generated current target value Ig of the alternator 12 is lowered as the charged state of the battery 11 approaches the fully charged state, it is possible to prevent overcharging of the battery during regeneration.

  Furthermore, since the generation current target value Ig is set to the generation allowable current α, the battery is fully charged when the S purge is completed. Therefore, the S purge time is secured and the regeneration of the NOx storage catalyst 4 is sufficiently possible. Thus, it is possible to maintain the battery 11 as close to full charge as possible while preventing overcharge of the battery 11. Thus, by bringing the state of charge of the battery 11 close to full charge during regeneration, surplus energy due to engine operation during regeneration is charged to the battery 11 as much as possible, and fuel consumption can be improved by using it after that.

  Since overcharge during the S purge is prevented, it is not necessary to significantly reduce the charge amount of the battery 11 before regeneration so as not to cause overcharge, and regeneration can be started easily. In this way, it is not necessary to significantly reduce the amount of charge of the battery 11 in advance before reproduction, and the battery 11 is controlled so that the state of charge of the battery 11 approaches full charge during reproduction. The deterioration of the state is suppressed, and for example, the operation time of the in-vehicle device such as the starter motor 12 can be sufficiently secured. In particular, overdischarge can be prevented when the capacity of the battery 11 is relatively at least.

In the present embodiment, when the current β that can be applied by the alternator 12 is lower than the power generation allowable current α, the current β that can be applied is set to the power generation current target value Ig of the alternator 12. The generated current target value Ig corresponding to the capacity is set, and the output torque of the engine 1 can be accurately controlled in accordance with the load of the alternator 12.
Furthermore, in this embodiment, the load of the alternator 12 is increased or decreased during the S purge in accordance with the catalyst temperature Tc. Therefore, the catalyst temperature Tc can be set to a temperature suitable for regeneration, and wasteful consumption of fuel is suppressed. S purge can be performed efficiently.

In the present embodiment, the charge amount of the battery 11 is reduced in advance before regeneration, but this is not a significant reduction, and it is desirable to reduce it as much as possible within a range in which the battery 11 is not overdischarged. In this way, by reducing the amount of charge of the battery 11, it is possible to further secure a regeneration opportunity.
In the present embodiment, the present invention is applied to the S purge of the NOx storage catalyst 4, but besides this, for example, the exhaust temperature of the engine 11 such as the NOx purge of the NOx storage catalyst 4 or forced regeneration of the DPF 5. The present invention can be applied at the time of regeneration of various exhaust gas purification means performed by raising the air pressure.

In the present embodiment, the present invention is applied to a diesel engine. However, a gasoline engine can also be applied to regeneration of an exhaust purification device such as a NOx storage catalyst.
The present invention can also be applied to a hybrid engine. In this case, the traveling drive and power generation motor 30 indicated by the broken line in FIG. 1 can be used as a generator instead of the alternator 12.

1 Engine 4 NOx storage catalyst 5 DPF
12 Alternator 20 ECU
21 Current sensor 22 Temperature sensor 30 Motor

Claims (6)

A generator driven by the engine to generate a variable amount of power and charge the battery, exhaust purification means for purifying exhaust provided in the exhaust passage of the engine, and load applied to the engine by power generation by the generator And regenerating means for regenerating the exhaust purification means by increasing the output torque of the engine to raise the temperature of the exhaust gas flowing into the exhaust purification means,
Charging state detecting means for detecting a chargeable capacity of the battery ;
Remaining reproduction time calculating means for calculating the remaining reproduction time by the reproducing means,
The regeneration means calculates a current that can be applied to the generator by subtracting a vehicle consumption current from a maximum generated current of the generator during the regeneration, and a chargeable capacity of the battery detected by the charge state detection means Is divided by the remaining regeneration time calculated by the remaining regeneration time calculating means to calculate a power generation allowable current, and when the applicable current is lower than the power generation allowable current, the applicable current is converted to the power generation of the generator. On the other hand, when the allowable power generation current is lower than the applicable current, the allowable power generation current is set as the power generation amount of the generator . Temperature detecting means for detecting the temperature of the exhaust purification means,
When the temperature of the exhaust purification unit detected by the temperature detection unit is equal to or higher than a first predetermined value, the regeneration unit reduces the power generation amount of the generator to reduce the load on the engine, claim temperature of the exhaust gas control means detected by said temperature detecting means when it is less than the first predetermined value, characterized in that by increasing the power generation amount of said generator to increase the load of the engine 2. An engine exhaust purification system according to 1. Said reproducing means, claims wherein when changing the power generation amount of the generator based on the state of charge of the battery during playback, wherein the gradually changing the output torque of the power generation amount and the engine The engine exhaust gas purification apparatus according to 1 or 2 . When the chargeable capacity of the battery detected by the charge state detection means is less than a second predetermined value, the chargeable capacity of the battery is increased to the second predetermined value at the start of reproduction by the reproduction means. The engine exhaust gas purification apparatus according to any one of claims 1 to 3 , further comprising regeneration preparation means for reducing the power generation amount of the generator in advance before regeneration. The exhaust purification means is a nitrogen oxide storage catalyst that stores nitrogen oxide in the exhaust,
5. The engine exhaust gas purification according to claim 1 , wherein the regeneration means regenerates the nitrogen oxide storage catalyst by removing sulfur oxide accumulated on the nitrogen oxide storage catalyst. apparatus. The engine is a hybrid engine having a motor as a drive source,
The engine exhaust purification device according to any one of claims 1 to 5 , wherein the generator is the motor.

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