JP6510459B2 - DPF manual regeneration control device - Google Patents

Description

  The present invention relates to a DPF manual regeneration control device, and more particularly to a DPF manual regeneration control device in an exhaust gas purification device of an engine provided with DPF manual regeneration means.

Conventionally, PM (particulate matter) contained in exhaust gas of a diesel engine is collected by a filter called a DPF (diesel particulate filter).
In a general DPF system, the PM deposition amount on the DPF is counted inside the ECU, and when the PM deposition amount exceeds a predetermined value, the DPF is automatically regenerated during traveling (automatic regeneration). Since automatic regeneration can be performed only when the exhaust gas temperature reaches a predetermined value or more, PM continues to be deposited on the DPF when idling at low exhaust gas temperature or low speed traveling such as traffic congestion continues.

  If the automatic regeneration impossible state continues and the PM deposition amount exceeds the predetermined value, the ECU prohibits the automatic regeneration and requests the user to perform forced regeneration (manual regeneration) at idling. If the user does not perform manual regeneration continuously and the PM deposition amount exceeds a predetermined value, the engine output is limited by the accelerator pedal opening degree or the limit of the maximum injection amount, etc., to prevent the DPF from being damaged.

  The engine rotation speed at which the manual regeneration is performed is obtained from a target rotation speed map for the environment (external temperature or intake air temperature, atmospheric pressure) set in the ECU. The target rotational speed is set to a value at which the required exhaust gas temperature can be obtained even with an engine having a low exhaust gas temperature, in consideration of exhaust gas temperature variation due to individual engine differences. Therefore, the engine having a high exhaust gas temperature is operated at a higher speed than necessary, resulting in unnecessary fuel consumption.

  Patent Document 1 discloses a technique of controlling an engine speed according to an individual engine difference at the time of manual regeneration. In Patent Document 1, the rotational speed is gradually increased by a predetermined width while monitoring the temperature of the gas containing DPF, and the gradual change is stopped when the temperature of the gas containing DPF after the elapse of the predetermined waiting time exceeds the predetermined temperature. As a result, it is possible to avoid the deterioration of fuel consumption due to the manual regeneration at an excessively high rotational speed.

JP, 2011-185178, A

  In Patent Document 1, first, the engine speed is set to a low value, and if the exhaust gas temperature stabilization wait → lower than a predetermined temperature, the engine speed is increased → exhaust gas temperature stabilization wait → ... while repeating the steps of manual regeneration execution speed Search for Therefore, in the case of an engine having a high exhaust gas temperature, the number of revolutions is determined in a short time from the start of the search, and the manual regeneration can be performed at a low number of revolutions.

  However, in the case of an engine whose exhaust gas temperature is originally low, it takes time to determine the manual regeneration implementation rotational speed, so in addition to consuming extra fuel compared to when manual regeneration is performed at a high rotational speed from the beginning, The prolonged time required also imposes a time burden on the user.

  The present invention has been made in view of the above problems, and an object thereof is to provide a DPF manual regeneration control device capable of performing manual regeneration with a minimum necessary number of revolutions according to individual engine differences. It is in.

The DPF manual regeneration control device for solving the above problems comprises a DPF provided in an exhaust passage of an engine, an oxidation catalyst provided on the upstream side of the exhaust passage with respect to the DPF, and an upstream of the oxidation catalyst in the exhaust passage. It is a DPF manual regeneration control device in an exhaust gas purification device of an engine provided with exhaust gas temperature confirmation means for confirming the exhaust gas temperature on the side and the manual regeneration means of the DPF. Then, the target rotational speed of the engine during manual regeneration of the manual regeneration means is calculated by the sum of a preset reference rotational speed and a feedback correction term including an individual difference adjustment amount for adjusting individual differences of the engine Computing means for The calculation means is an ISC calculated as the individual difference adjustment amount by injection amount feedback control of a fuel injection amount implemented to maintain a specific engine speed during idle operation of the individual of the individual difference adjustment amount. the feedback term Ru used.

  According to this configuration, since the ISC feedback term is used to predict the injection amount difference during idle operation relative to the reference individual to calculate the engine target speed during manual regeneration, the engine target during manual regeneration The individual difference adjustment amount is appropriately reflected in the calculation of the number of revolutions, and manual regeneration can be performed with the minimum number of revolutions according to the individual engine differences.

  The calculation means may calculate the target rotational speed with the individual difference adjustment amount constituting the feedback correction term being constant. According to this configuration, as compared with the case where the individual difference adjustment amount is also calculated by feedback control, the time until the target rotation number is determined can be shortened by that amount, and unnecessary fuel consumption becomes unnecessary.

  The calculation means may perform feedback control of the target rotation speed also with respect to the individual difference adjustment amount constituting the feedback correction term. According to this configuration, it is possible to obtain a more appropriate target rotation speed than when the individual difference adjustment amount is constant and feedback control of the individual difference adjustment amount is not performed.

  According to the present invention, it is possible to perform manual regeneration at a minimum necessary number of revolutions according to individual engine differences.

The schematic block diagram of an exhaust gas purification device. (A) is a figure which shows the relationship between fuel injection quantity and exhaust gas temperature, (b) is a figure which shows the relationship between idle rotation speed and exhaust gas temperature. The figure which shows the relationship of an ISC feedback term and a required rotation speed adjustment amount. Flow chart of DPF manual regeneration control.

An embodiment of the present invention will now be described with reference to FIGS. 1 to 4.
As shown in FIG. 1, the DPF 13 and the oxidation catalyst (DOC) 14 are provided in the exhaust passage 12 connected to the exhaust side of the engine 11, and the oxidation catalyst 14 is provided upstream of the exhaust passage 12 than the DPF 13. It is done. On the upstream side of the oxidation catalyst 14 of the exhaust passage 12, a temperature sensor 15 as exhaust gas temperature confirmation means for confirming the exhaust gas temperature is provided. On the upstream side of the oxidation catalyst 14 of the exhaust passage 12 and on the downstream side of the temperature sensor 15, an injector 16 for injecting fuel (for example, light oil) in a spray state is provided. The exhaust passage 12 is provided with a differential pressure sensor 17 that detects a differential pressure between the exhaust upstream side of the DPF 13 and the exhaust downstream side thereof.

  Various controls of the engine 11 are implemented by a control unit (ECU) 30. The control device 30 inputs / outputs signals to / from a CPU that executes various arithmetic processing, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores calculation results of the CPU, etc. It has an input / output port for The control device 30 performs an automatic regeneration control means for automatically executing a filter regeneration process for burning and removing the PM accumulated in the DPF 13 when the vehicle is traveling, and a manual regeneration control means for executing the filter regeneration process when the vehicle is stopped by a driver's operation input. Configure

  In addition to the above-described sensors, the input port of the control unit (ECU) 30 also includes various sensors necessary for traveling of the vehicle, for example, an accelerator sensor 18 for detecting an amount of depression of an accelerator pedal, an engine speed sensor 19 and A manual regeneration switch 21 for starting manual regeneration control by ON operation is connected. Further, the output port is connected with warning means 22 for giving a warning to the driver when the amount of PM deposited in the DPF 13 exceeds a predetermined value described later. For example, a warning indicator light is used as the warning means 22.

  The control device 30 performs filter regeneration control for burning and purifying the PM accumulated in the DPF 13 in order to remove the PM collected by the DPF 13 by the operation of the engine 11. The filter regeneration control is performed by supplying an unburned fuel component to the oxidation catalyst 14. Then, the temperature of the DPF 13 is raised by the heat generation associated with the oxidation of the unburned fuel component in the exhaust gas and on the oxidation catalyst 14, and the PM deposited on the DPF 13 is burned and removed. The supply of the unburned fuel component at the time of the filter regeneration control is performed by fuel injection from the injector 16.

  The automatic regeneration (automatic regeneration processing) automatically executed when the vehicle travels is executed by the control device 30 as an automatic regeneration control unit, and the amount of PM collected in the DPF 13 when the vehicle travels (hereinafter referred to as PM deposition When the quantity exceeds the first predetermined value, the filter regeneration control is automatically performed. On the other hand, the manual regeneration is executed by the control device 30 as a manual regeneration control means, and when the PM deposition amount deposited on the DPF 13 exceeds a second predetermined value, a warning is issued by the warning means 22 and the driver manually The regeneration control of the DPF 13 is performed when the vehicle is stopped by the operation input of the regeneration switch 21.

  The driver's operation input, that is, the manual regeneration (manual regeneration processing) executed when the vehicle is stopped by the ON operation of the manual regeneration switch 21 does not sufficiently regenerate the DPF 13 by only the automatic regeneration while the vehicle is traveling This is performed in such a case, and by performing the filter regeneration control even when the vehicle is stopped, the combustion removal of PM is surely performed. Therefore, the second predetermined value used at the start of the manual regeneration is set to a value larger than the first predetermined value used at the start of the automatic regeneration. Further, the PM deposition amount in the DPF 13 is estimated by the pressure difference between the upstream side and the downstream side of the DPF 13 detected by the differential pressure sensor 17. That is, utilizing the fact that the differential pressure increases as the PM deposition amount increases, the PM deposition amount is estimated based on the differential pressure, that is, the detection value of the differential pressure sensor 17. The PM deposition amount is stored as a count value of a PM counter (not shown), and the count value of the counter is updated according to the change in the PM deposition amount.

  The control device 30 as computing means for computing the target number of revolutions of the engine 11 at the time of manual regeneration of the manual regeneration means includes a preset reference number of revolutions and an individual difference adjustment amount for adjusting individual differences of the engines. The target rotation number is calculated by the sum of the feedback correction term.

  Next, the operation of the engine exhaust purification system will be described. In the engine exhaust purification device, when the PM deposition amount collected by the DPF 13 exceeds a predetermined regeneration start value, the regeneration process of the DPF 13 is started and fuel is injected from the injector 16. The injected fuel is combusted when it reaches the oxidation catalyst 14, whereby the exhaust temperature is increased. Then, the exhaust gas heated by the oxidation catalyst 14 flows into the DPF 13 to raise the temperature of the DPF 13, whereby the PM deposited on the DPF 13 is burnt and the DPF 13 is regenerated. Then, when the PM deposition amount decreases to a predetermined regeneration end value or less, the fuel injection from the injector 16 is ended, and the regeneration processing is ended. The reproduction process is performed under the control of the control device 30.

  Since automatic regeneration can be performed only when the exhaust gas temperature reaches a predetermined value or more, PM continues to be deposited on the DPF 13 when idling at low exhaust gas temperature or low speed traveling such as traffic congestion continues. When the non-reproducible state continues and the PM deposition amount exceeds the predetermined value, the control device 30 prohibits the automatic regeneration and requests the driver (user) to perform forced regeneration (manual regeneration) at idling.

  The control device 30 performs manual regeneration control according to the flowchart shown in FIG. That is, in the manual regeneration control, it is determined whether the PM counter is equal to or more than the manual regeneration start threshold (step S1), whether the vehicle stop determination is ON or not (step S2), and whether the manual regeneration switch is ON or not ( Step S3), setting a target engine speed at manual regeneration (step S4), DPF regeneration (step S5), determining whether the PM counter is less than a manual regeneration end threshold (step S6), normal engine speed It is performed by seven steps of processing (Step S7) of returning to.

  That is, first, in step S1, the control device 30 determines whether the PM counter is equal to or more than the manual regeneration start threshold. If the PM counter is equal to or more than the manual regeneration start threshold, the process proceeds to step S2, and the PM counter is manually regenerated in step S1. If it is less than the start threshold value, the DPF manual regeneration control is ended. In step S2, it is determined whether the vehicle stop determination is ON. If the vehicle stop determination is ON, the process proceeds to step S3. In step S3, it is determined whether the manual regeneration switch is ON. If it is determined in step S3 that the manual regeneration switch is ON, the process proceeds to step S4, and after setting the target engine speed in step S4, DPF regeneration is started in step S5.

  After the start of DPF regeneration, it is determined in step S6 whether the PM counter is less than the manual regeneration end threshold, and if the PM counter is less than the manual regeneration end threshold, the process proceeds to step S7 and the engine rotational speed is returned to the normal value After that, the manual regeneration control is ended.

Among these, the control of step S4 for setting the target engine rotational speed at the time of manual regeneration is different from the conventional control. Next, setting of the target engine speed will be described.
The regeneration of the DPF 13 is performed by causing a high temperature exhaust gas heated by the heat of oxidation reaction generated by the fuel supply to the oxidation catalyst (DOC) 14 provided upstream of the DPF 13 to flow into the DPF 13. In order for the oxidation reaction in the oxidation catalyst 14 to occur, it is necessary that the temperature of the gas containing the oxidation catalyst be equal to or higher than the activation temperature of the oxidation catalyst 14.

  Generally, the temperature of the oxidation catalyst-containing gas at idle operation, that is, the temperature of the engine exhaust gas is lower than the activation temperature of the oxidation catalyst 14. For example, the engine speed during idle operation is 600 to 800 rpm, and the exhaust gas temperature is 100 to 150 ° C. Generally, the exhaust gas temperature at idle operation is proportional to the engine speed. Therefore, at the time of DPF manual regeneration, the engine speed is changed to a value higher than that at normal time, for example, about 2000 rpm, and the exhaust gas temperature is raised to about 200.degree.

  However, due to the individual differences of the engine 11, there are individuals with high exhaust gas temperature and low exhaust gases even at the same rotation speed. Therefore, when it is desired to control at the same exhaust gas temperature, it is necessary to set the number of individuals with high exhaust gas temperature to a low rotational speed and the number of individual with low exhaust gas temperature to a high rotation number.

  There are various causes of the exhaust gas temperature difference due to individual engine differences, such as the difference in engine friction and the difference in fuel injection amount, but the difference in fuel injection amount is most dominant in the same environment (outside temperature, water temperature, atmospheric pressure) .

  Therefore, if the injection amount difference at the time of idle operation with respect to the individual having the performance as a reference is known in advance before performing the manual regeneration, it is possible to predict the engine rotational speed necessary for performing the manual regeneration. The ISC (idle speed control) feedback term is used to predict the injection amount difference.

  The fuel injection amount of the diesel engine is controlled according to the engine speed and the accelerator pedal opening degree. For example, this is performed using a map for the engine speed and the accelerator pedal opening degree set in the ECU.

  However, since it is necessary to keep the engine rotational speed constant during idle operation, engine individual differences are absorbed by performing injection amount feedback control in addition to the injection amount calculated in the above map.

The injection amount adjustment amount at this time is an ISC feedback term (ISC F / B term). The ISC feedback term, the injection amount, and the exhaust gas temperature satisfy the following relationship.
If the ISC feedback term is large, a large amount of injection is required to maintain the idle speed, and the exhaust gas temperature at idle speed is high.

-If the ISC feedback term is small, the idle rotation speed can be maintained with a small injection amount, and the exhaust gas temperature at idle rotation is low.
Further, as shown in FIG. 2 (a), the sensitivity of the exhaust gas temperature to the injection amount is substantially constant, and as shown in FIG. 2 (b), the relationship between the engine speed and the exhaust gas temperature in idle operation is also substantially constant. is there. Therefore, the relationship shown in FIG. 3 is derived from the relationship between the ISC feedback term (ISC F / B term) and FIGS. 2A and 2B, and the relationship shown in FIG. 3 is set in the control unit (ECU) 30. Thus, it is possible to predict the required number of revolutions adjustment of the individual with respect to the number of engine revolutions required when performing manual regeneration with the reference engine, ie, the individual difference adjustment amount (ΔNE).

  In addition, in the target rotation speed obtained from the individual difference adjustment amount (ΔNE) predicted in FIG. 3, when the exhaust gas temperature does not reach the predetermined exhaust gas temperature, the engine rotation according to the difference between the predetermined exhaust gas temperature and the current exhaust gas temperature Implement feedback control to fine-tune the number. The control unit (ECU) 30 calculates the ISC feedback term, for example, in a cycle of 8 to 18 ms, and always calculates the individual difference adjustment amount (ΔNE) from the latest state.

That is, the target rotation speed at the time of manual regeneration is determined by Equation 1.
Target rotational speed = reference rotational speed + individual difference adjustment amount (ΔNE) + feedback correction term Equation 1
The reference rotational speed is preset in the ECU as a fixed value.

The individual difference adjustment amount (ΔNE) is derived from FIG.
The feedback correction term is calculated from the difference between the target exhaust gas temperature and the current value (exhaust gas temperature sensor output or exhaust gas temperature estimated value) when operating at the reference rotation speed + the individual difference adjustment amount (ΔNE).

As described above, at the time of manual regeneration, manual regeneration can be performed at a minimum necessary number of revolutions according to the individual engine differences.
The reason why feedback control including the individual difference adjustment amount (ΔNE) is not set in Equation 1 is that the target rotation number is determined by the amount when the individual difference adjustment amount (ΔNE) is also calculated by feedback control. It takes a long time, and in the meantime, extra fuel consumption is required.

According to this embodiment, the following effects can be obtained.
(1) The DPF manual regeneration control device includes the DPF 13 provided in the exhaust passage 12 of the engine 11, the oxidation catalyst 14 provided on the upstream side of the exhaust passage 12 with respect to the DPF 13, and the upstream of the oxidation catalyst 14 in the exhaust passage 12 It is a DPF manual regeneration control device in an exhaust gas purification device of an engine provided with exhaust gas temperature confirmation means (temperature sensor 15) for confirming the exhaust gas temperature on the side and the manual regeneration means of the DPF 13. The target rotational speed of the engine 11 at the time of manual regeneration of the manual regeneration means is a reference correction number set in advance and a feedback correction term including an individual difference adjustment amount (.DELTA.NE) for adjusting individual differences between engines. An arithmetic unit (control device 30) for calculating by the sum is provided.

  According to this configuration, in the calculation of the target rotational speed of the engine 11 at the time of manual regeneration, the ISC feedback term is used to predict the injection amount difference at the time of idle operation relative to the reference individual. The individual difference adjustment amount (ΔNE) is appropriately reflected in the calculation of the target rotation number, and manual regeneration with a minimum necessary rotation number according to the engine individual difference becomes possible. Therefore, the effects of suppressing unnecessary fuel consumption, suppressing noise, and suppressing heat damage near the exhaust pipe outlet can be expected.

  (2) The control device 30 calculates the target rotational speed of the engine 11 at the time of manual regeneration, with the individual difference adjustment amount (ΔNE) constituting the feedback correction term being constant. According to this configuration, compared to the case where the individual difference adjustment amount (ΔNE) is also calculated by feedback control, the time to determine the target rotation speed can be shortened by that amount, and unnecessary fuel consumption becomes unnecessary. .

The embodiment is not limited to the above, and may be embodied as follows, for example.
The exhaust gas temperature confirmation means is not limited to the temperature sensor 15 that directly detects the exhaust gas temperature, and may be configured to calculate the exhaust gas temperature as an estimated value. As a representative example of the exhaust gas temperature estimated value calculation, calculation from the map for the engine speed and fuel injection amount set in the ECU, and the intake temperature, engine coolant temperature, atmospheric pressure, exhaust pipe pressure etc. There are some that add corrections.

  The controller 30 performs feedback control also on the individual difference adjustment amount (ΔNE) without calculating the target rotation number for manual regeneration with the individual difference adjustment amount (ΔNE) constituting the feedback correction term constant. May be In this case, the individual difference adjustment amount (ΔNE) is constant, and a more appropriate target rotation number can be obtained as compared to the case where feedback control of the individual difference adjustment amount (ΔNE) is not performed.

The controller 30 may set the target rotational speed to be high immediately after the start of the cold morning.
○ The fuel addition method to the exhaust gas is not limited to the one in which the injector 16 is provided in the exhaust pipe (exhaust passage 12), and the post injection using the injector that injects the fuel to the combustion chamber (injection of fuel to the exhaust gas after explosion Yes).

  In addition to the method using the differential pressure sensor 17, the PM deposition amount may be estimated using a PM emission map set in the control device 30.

  11: Engine, 12: Exhaust passage, 13: DPF, 14: Oxidation catalyst, 15: Temperature sensor as exhaust gas temperature confirmation means, 30: Control device as manual regeneration means and calculation means.

Claims (3)

DPF provided in an exhaust passage of an engine, an oxidation catalyst provided on the upstream side of the exhaust passage with respect to the DPF, and exhaust gas temperature confirming means for confirming an exhaust gas temperature upstream of the oxidation catalyst in the exhaust passage A DPF manual regeneration control device in an exhaust gas purification device of an engine comprising: the DPF manual regeneration means;
Calculation to calculate the target engine speed of the engine at the time of manual regeneration of the manual regeneration means by the sum of a preset reference engine speed and a feedback correction term including the individual difference adjustment amount for adjusting individual differences of the engine Equipped with
The calculation means is an ISC calculated as an injection amount feedback control of a fuel injection amount implemented to maintain a specific engine speed during idle operation of an individual of the individual difference adjustment amount as the individual difference adjustment amount. DPF manual regeneration control device comprising a benzalkonium using feedback term.   The DPF manual regeneration control device according to claim 1, wherein the calculation means calculates the target rotation number with the individual difference adjustment amount constituting the feedback correction term being constant.   The DPF manual regeneration control device according to claim 1, wherein the calculation means performs feedback control of the target rotation speed also with respect to the individual difference adjustment amount constituting the feedback correction term.

Images