JP2008232073A - Exhaust emission purifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission purifier of continuous regeneration type capable of certainly performing the forced regeneration (forced combustive removal of deposited PM) using a simple constitution even if the properties of the fuel have changed. <P>SOLUTION: The exhaust emission purifier of continuous regeneration type is equipped with a means (S9 in Fig.2) to set the forced regenerating temperature and the forced regenerating time in accordance with presumption of the PM deposited amount when the forced regenerating conditions are judged as being met, a means (S10 in Fig.2) to control the adding amount of the fuel to inside a cylinder or to a catalyst so as to maintain the filter temperature upon raising to the forced regenerating temperature when the catalyst temperature is at or over the lower limit value of the activation point if the forced regenerating conditions are met, a means (not illustrated) to correct the control amount by multiplying with an adjustment factor in order to let the control amount comply with the change of the fuel properties, a means (S1-S6 in Fig.4) to measure the elapsed time with the out-of-reference time when the filter temperature is below the regeneration starting temperature during control of the fuel adding amount, and a means (S7-S8 in Fig.4) to alter the set adjustment factor to the larger side when the measured time attains the prescribed time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust emission control device for removing PM (particulate matter) contained in exhaust gas from a diesel engine.

  In recent years, development of a continuous regeneration type exhaust purification device (CR-DPF: Continuous Regeneratoin-Diesel Particulate Filter) has been promoted as one of the promising means for reducing PM contained in diesel engine exhaust.

  The continuously regenerative exhaust purification device continuously removes the accumulated PM by the action of a catalyst while collecting PM contained in the exhaust of the engine in a filter. Even in such an exhaust purification device, the catalyst has an activation temperature, and if the operation state at an exhaust temperature lower than this is continued for a long time, the filter is not continuously regenerated sufficiently, and the PM accumulation amount is excessive. This may adversely affect engine performance. In addition, when the catalyst temperature shifts to an operating state where the activation temperature exceeds the activation temperature, the PM accumulated excessively on the filter may burn rapidly, and the filter is liable to be melted or cracked. Therefore, forced combustion removal (forced regeneration) of the deposited PM is performed at a necessary time.

As for forced regeneration, there is a method of delaying the fuel injection timing to raise the filter temperature to be higher than the regeneration start temperature (Patent Document 1, Patent Document 2). If the fuel injection timing is retarded, the exhaust temperature will rise more than in the case of normal injection, and the unburned HC in the exhaust will increase, so the exhaust will be further heated by the heat generated by the oxidation reaction of the catalyst, and the filter temperature Is raised above the regeneration start temperature.
JP 2005-048709 A JP 2004-124855 A

  In recent years, bioethanol fuel and the like are attracting attention in order to reduce the environmental burden. If bioethanol fuel or the like is used in an engine equipped with a continuous regeneration type exhaust purification device, the forced regeneration may not be performed as designed because the fuel property differs from that of light oil. Excessive or insufficient temperature rise may cause filter regeneration failure or filter melting. Patent Document 1 discloses a means for calculating a PM accumulation amount together with a component based on a PM component emission characteristic that varies depending on fuel properties.

  An object of the present invention is to provide means capable of reliably performing forced regeneration (forced combustion removal of deposited PM) with a simple configuration even if the fuel properties change.

  According to a first aspect of the present invention, there is provided an exhaust gas purification apparatus for burning PM accumulated in a filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, and means for estimating the PM accumulation amount of the filter, predetermined forced regeneration Means for determining whether the condition is satisfied, means for setting the forced regeneration temperature and forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and determination that the forced regeneration condition is satisfied A means to control the amount of fuel added to the cylinder or to maintain the filter temperature at the forced regeneration temperature when the catalyst is above the lower limit of the activation temperature, and this control amount corresponds to changes in fuel properties Means for multiplying by an adjustment coefficient to correct, means for setting the adjustment coefficient used for this correction to be changeable, and the elapsed time of the non-reference temperature at which the filter temperature falls below the regeneration start temperature during control of the fuel addition amount. Means for measuring, means for changing the setting of the adjustment factor the measured time reaches the predetermined time the larger side, characterized in that it comprises a.

  According to a second aspect of the present invention, there is provided an exhaust purification apparatus for burning PM accumulated in a filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, and means for estimating the PM accumulation amount of the filter, predetermined forced regeneration Means for determining whether the condition is satisfied, means for setting the forced regeneration temperature and forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and determination that the forced regeneration condition is satisfied A means to control the amount of fuel added to the cylinder or to maintain the filter temperature at the forced regeneration temperature when the catalyst is above the lower limit of the activation temperature, and this control amount corresponds to changes in fuel properties Means for multiplying by an adjustment coefficient to correct, means for setting the adjustment coefficient used for this correction to be changeable, and the elapsed time of the non-reference temperature at which the filter temperature exceeds the forced regeneration temperature during control of the fuel addition amount. Means for measuring, means for changing the setting of the adjustment factor the measured time reaches the predetermined time to the small side, characterized in that it comprises a.

  According to a third aspect of the present invention, there is provided an exhaust purification apparatus for burning PM accumulated in a filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, and means for estimating the PM accumulation amount of the filter, predetermined forced regeneration Means for determining whether the condition is satisfied, means for setting the forced regeneration temperature and forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and determination that the forced regeneration condition is satisfied A means to control the amount of fuel added to the cylinder or to maintain the filter temperature at the forced regeneration temperature when the catalyst is above the lower limit of the activation temperature, and this control amount corresponds to changes in fuel properties Means for multiplying by an adjustment coefficient to correct, means for setting the adjustment coefficient used for this correction to be changeable, and the elapsed time of the non-reference temperature at which the filter temperature falls below the regeneration start temperature during control of the fuel addition amount. Means for measuring, means for changing the setting of the adjustment coefficient to the larger side when the measurement time reaches a predetermined time, means for measuring the elapsed time of the non-standard temperature at which the filter temperature exceeds the forced regeneration temperature during control of the fuel addition amount And a means for changing the setting of the adjustment coefficient to a smaller side when the measurement time reaches a predetermined time.

  According to a fourth aspect of the present invention, in the exhaust gas purification apparatus according to any one of the first to third aspects, the adjustment coefficient is changed to a setting corresponding to a moving average value of the filter temperature. .

  According to a fifth aspect of the present invention, in the exhaust purification apparatus according to any one of the first to fourth aspects of the present invention, means for measuring the number of times the adjustment coefficient change is repeated, and means for prohibiting repetition exceeding the predetermined number In addition, after the predetermined number of changes, there is provided means for stopping the forced regeneration and warning the cancellation when the elapsed time of the non-reference temperature reaches a predetermined time.

  According to a sixth aspect of the present invention, in the exhaust emission control device according to any one of the first to fifth aspects, when it is determined that the forced regeneration condition is satisfied, the catalyst temperature falls below a lower limit value of the activation temperature. Means for positively increasing the exhaust temperature in order to raise the catalyst temperature above the lower limit of the activation temperature.

  In the first invention, when it is determined that the forced regeneration condition is satisfied, fuel is added to the cylinder or to the catalyst when the catalyst is equal to or higher than the lower limit value of the activation temperature. Since the added fuel reacts on the catalyst, the temperature of the exhaust is raised by the heat of reaction. The amount of fuel added is controlled so that the filter is maintained at the forced regeneration temperature. However, when the fuel property changes, the reaction heat on the catalyst also changes, so the temperature rise characteristic of the exhaust changes. To cope with this, the adjustment coefficient for correcting the fuel addition amount (control amount) is set to be changeable, and when the filter temperature falls below the regeneration start temperature during the control of the addition amount, the elapsed time of the non-standard temperature When the measurement time reaches a predetermined time, the setting of the adjustment coefficient is changed to the large side. Therefore, the control characteristics of the fuel addition amount are corrected to the increase side, the reaction heat on the catalyst is also increased, insufficient temperature rise due to changes in fuel properties is prevented, and forced regeneration (burned PM removal and combustion) can be performed reliably. It becomes like this.

  In the second invention, the amount of fuel added is controlled to maintain the filter at the forced regeneration temperature, but when the filter temperature exceeds the forced regeneration temperature, the elapsed time of the non-reference temperature is measured, When the measurement time reaches the specified time, the adjustment coefficient setting is changed to the smaller side, so the control characteristics of the fuel addition amount are corrected to the reduced side, the reaction heat on the catalyst is reduced, and the fuel properties change. Excessive temperature rise is prevented, and forced regeneration (burned PM removal) can be reliably performed without causing filter melting or the like.

  In the third aspect of the invention, it is possible to cope with changes in fuel properties by changing the adjustment coefficient, and during forced regeneration, the filter temperature can be controlled above the regeneration start temperature and below the forced regeneration temperature. For this reason, it is possible to prevent the forced regeneration failure of the filter and the melting damage of the filter, and to improve the reliability with respect to the forced regeneration.

  In the fourth aspect of the invention, since the adjustment coefficient is changed to a setting corresponding to the moving average value of the filter temperature, the change in the fuel property can be accurately reflected in the forced regeneration control.

  In the fifth invention, after the adjustment coefficient is changed, if the fuel addition amount (control amount) is not sufficiently corrected, the adjustment coefficient is repeatedly changed. However, a limit is set for the number of changes, and a change exceeding the limit is made. Since forced regeneration is stopped, the waste of fuel addition can be suppressed. In addition, the alarm can prompt appropriate measures (such as changing the fuel).

  In the sixth invention, when it is determined that the forced regeneration condition is satisfied, when the catalyst temperature is lower than the lower limit value of the activation temperature, the exhaust temperature is positively increased, and the catalyst temperature is lower than the lower limit value of the activation temperature. If it exceeds the value, the fuel addition control is started, so that the forced regeneration can be effectively performed even in the operation region where the catalyst cannot be sufficiently activated.

  In FIG. 1, reference numeral 10 denotes a diesel engine, which includes a common rail fuel injection device (not shown). A compressor, an intercooler 13, and an intake throttle valve 14 of the turbocharger 12 are interposed in the intake passage 11 of the engine 10. A turbine of the turbocharger 12, an exhaust throttle valve 16, and a continuous regeneration filter device (CR-DPF) 17 are installed in the exhaust passage 15 of the engine 10. The common rail fuel injection device includes a high-pressure pump that accumulates fuel in the common rail, and a fuel supply pipe that connects the injection nozzle of each cylinder to the common rail. The control unit 20 controls the fuel injection device and the preheating means described later. In addition to the normal control, the temperature increase control for forced regeneration is set. 18 is an EGR valve of an EGR (exhaust gas recirculation) device, 19 is a turbo bypass opening / closing valve (turbo bypass valve) that bypasses the turbine of the turbocharger 12, and 29 is an EGR cooler.

  The CR-DPF 17 includes a DPF 21 (Diesel Particulate Filter) and an oxidation catalyst 22 (DOC: Diesel Oxidation Catalyst). The DPF 21 is formed in a honeycomb structure, and the inlets and outlets of flow paths (cells) partitioned in a lattice shape are alternately sealed. That is, the flow path sealed at the inlet and the flow path sealed at the outlet are alternately adjacent to each other, and the porous partition walls that partition these allow passage of the exhaust gas. In this example, a catalyst regeneration type filter (CSF: Catalyst Soot Filter) is employed in order to set a combustible ignition temperature of PM collected in the partition walls. DOC22 is formed in a honeycomb structure carrying a catalyst, and mainly oxidizes HC and NOx contained in the exhaust gas that passes through the flow path partitioned in a lattice shape of the honeycomb structure. The catalyst temperature rises to promote the combustion of the deposited PM.

  As a detection means necessary for the control of the control unit 20, in addition to a rotation sensor (also serving as a crank angle sensor) for detecting the engine speed Ne and an accelerator opening sensor for detecting the engine load Q, a differential pressure before and after the CR-DPF 17 is used. A differential pressure sensor 23 for detecting, a temperature sensor 26 for detecting the inlet temperature of the CR-DPF 17, a temperature sensor 25 for detecting the intermediate temperature 24 of the CR-DPF 17, a temperature sensor 25 for detecting the outlet temperature of the CR-DPF 17, and an intake air amount ( An air flow sensor 27 for detecting an intake air flow rate) is provided.

  FIG. 7 exemplifies the relationship between the PM accumulation amount and the exhaust gas temperature. When the exhaust gas temperature exceeds the reference temperature at which the PM emission amount = the PM combustion amount, the PM combustion amount> the PM emission amount. Thus, while the PM accumulation amount decreases, when the exhaust gas temperature is lower than the reference temperature, the PM combustion amount is smaller than the PM emission amount, and the PM accumulation amount increases. For this reason, if the PM accumulation amount exceeds a predetermined value by continuing the operation state of the exhaust temperature lower than the reference temperature, forced regeneration is necessary to avoid a decrease in engine performance.

  The control unit 20 determines a fuel injection signal (a main injection amount command and a main injection timing command) to each injection nozzle based on normal control from the engine speed Ne and the engine load Q. When it is determined that the forced regeneration of the CR-DPF 17 is necessary, the temperature is switched to the forced regeneration temperature control, and the inlet temperature (exhaust temperature) of the CR-DPF 17 falls below the lower limit of the catalyst activation temperature (for example, 230 ° C.). In addition to driving the catalyst preheating means based on the temperature raising control 1, the fuel injection signal (after injection amount command and after When the CR-DPF inlet temperature is equal to or higher than the lower limit value of the catalyst activation temperature, post injection is performed at a timing significantly delayed from the main injection based on the temperature increase control 2. Such a fuel injection signal (post injection amount command and post injection timing command) is determined.

  As for the catalyst preheating means, the EGR valve 18, the intake throttle valve 14, the exhaust throttle valve 16, and the turbo bypass valve 19 are used for control to positively increase the exhaust temperature of the engine. When the turbocharger 12 is a variable nozzle type, it is conceivable to control the variable nozzle as a catalyst preheating means instead of the turbo bypass valve.

  For determining whether or not the forced regeneration of CR-DPF 17 is necessary, the PM accumulation amount of DPF 21 (the subtraction value between the PM emission amount estimated from the operating state and the PM combustion amount estimated from the PM combustion characteristic of the filter) Means (S2 in FIG. 2) for determining the forced regeneration time when the calculated value) is greater than or equal to the predetermined value (S2 in FIG. 2), and means for determining the forced regeneration time when the differential pressure before and after the CR-DPF 17 is greater than or equal to the predetermined value 2) S4), and when the operation time (or driving distance) measured from the completion of forced regeneration based on the PM accumulation amount reaches the interval set for forced regeneration, forced regeneration when there is no forced regeneration history When the operation time (or the operation distance or the number of forced regenerations) reaches the 0 reset forced regeneration interval that periodically initializes the PM accumulation amount, the forced regeneration time is determined. Means for determining (S8 in FIG. 2); It is set.

  The forced regeneration time of the CR-DPF 17 is determined based on a plurality of such different methods. When any of these determinations is received, the forced mode corresponding to the PM deposition amount is determined as a forced mode corresponding to the determination method at that time. A means for determining the regeneration temperature Treg and the forced regeneration time T (S9 in FIG. 2) is set. The forced regeneration temperature Treg (target temperature of the temperature increase control 2) and the forced regeneration time T are set according to the PM accumulation amount assumed in each forced regeneration mode. The forced regeneration temperature Treg is set lower as the PM deposition amount is larger, and the forced regeneration time T is set longer as the forced regeneration temperature Treg is lower.

  Regarding the calculation of the PM accumulation amount (S1 in FIG. 2), the PM emission amount per unit time is obtained based on the engine speed Ne and the engine load Q. On the other hand, based on the PM combustion characteristics of the DPF, the PM combustion amount per unit time is obtained under the exhaust conditions in which the combustion of the deposited PM is started by the oxidation action of the catalyst. Specifically, the PM combustion speed of the DPF is obtained from the DPF temperature (estimated from the detected values of the temperature sensors 24 and 25) and the space velocity (exhaust flow rate / filter capacity), and converted into the PM fuel amount per unit time. To do. Then, the PM accumulation amount of the DPF is obtained by sequentially integrating the subtraction value obtained by subtracting the PM combustion amount from the PM emission amount. Since the integrated value may be negative, a process for correcting the negative integrated value = 0 is set.

  2 and 3 are flowcharts for explaining the control contents of the control unit 20. In S1, a subtraction value between the PM emission amount estimated from the operating state and the PM combustion amount estimated from the PM combustion characteristic of the filter. The calculated value that integrates is obtained. In S2, it is determined whether or not the calculated value of the PM accumulation amount is equal to or greater than a predetermined value (threshold value). In S3, the differential pressure before and after CR-DPF 17 is read. In S4, it is determined whether or not the differential pressure before and after the CR-DPF 17 is equal to or greater than a predetermined value (threshold). In S5, the operation time count value is read. In S6, it is determined whether or not the count value of the operation time has reached the interval for forced regeneration and whether or not there is a history of forced regeneration during that time. In S7, the operation time count value is read. In S8, it is determined whether or not the count value of the operation time has reached the zero reset forced regeneration interval.

  If the determination of S2 is no, the determination of S4 is no, the determination of S6 is no, and the determination of S8 is no, the process returns to S1. If the determination of S2 is yes or the determination of S4 is yes or the determination of S6 is yes or the determination of S8 is yes, the process proceeds to S9. In S9, the forced regeneration mode is selected depending on whether the forced regeneration timing determination (yes) depends on any of the determinations in S2 to S8. When based on the determination of S2, the forced regeneration temperature Treg1 and the forced regeneration time T1 are set in the forced regeneration mode corresponding to the excess of the PM accumulation amount. When based on the determination of S4, the forced regeneration temperature Treg2 or the forced regeneration time T2 is set by the forced regeneration mode corresponding to the excess of the differential pressure. When the determination in S6 is performed, the forced regeneration temperature Treg3 and the forced regeneration time T3 are set in the forced regeneration mode corresponding to the forced regeneration interval. When the determination in S8 is made, the forced regeneration temperature Treg4 and the forced regeneration time T4 are set in the forced regeneration mode corresponding to the zero reset forced regeneration interval.

  In S10, forced regeneration is executed based on the selected forced regeneration mode. When the inlet temperature of the CP-DPF 17 is equal to or higher than the lower limit of the catalyst activation temperature, the post-injection is performed at a timing significantly delayed from the main injection while monitoring the intermediate temperature of the CR-DPF 17 and the outlet temperature of the CR-DPF 17 (Temperature rising control 2). When the CP-DPF 17 inlet temperature falls below the lower limit of the catalyst activation temperature, the catalyst preheating means is controlled while monitoring the intermediate temperature of the CR-DPF 17, and if necessary, combustion follows the main injection. The fuel injection device is controlled to perform after injection at a possible timing (temperature increase control 1). In after-injection, the amount of heat not used for power out of the amount of heat generated by the fuel increases, and the exhaust temperature rises. When the inlet temperature of the CR-DPF 17 exceeds the lower limit value of the activation temperature of the catalyst, the temperature rise control 1 is switched to the temperature rise control 2, and the post-injection causes the added fuel to oxidize on the catalyst. The heat of reaction accelerates the combustion process of the deposited PM.

  In S11, it is determined whether the temperature is higher than the forced regeneration temperature and whether the forced regeneration time count condition is satisfied. In S12, it is determined whether or not the count (elapsed time when the DPF temperature is equal to or higher than the forced regeneration temperature) has reached the forced regeneration time T. When the determination of S11 is yes and the determination of S12 is yes, the process proceeds to S13, and the forced regeneration mode is reset. In S14, the forced regeneration is terminated and the normal fuel injection control is restored.

  As described above, regarding the determination of the forced regeneration timing of the DPF 21, the determination method based on the estimation of the PM accumulation amount, the determination method based on the differential pressure level, the determination method based on the forced regeneration interval, and the zero reset forced regeneration Since the determination method based on the interval is used in combination, and these checks work, the probability that the PM accumulation amount will be excessive can be increased. The forced regeneration temperature Treg and the forced regeneration time T corresponding to the PM accumulation amount assumed as the forced regeneration mode corresponding to these determination methods are set, and until the termination condition based on these is satisfied, the temperature of the CR-DPF 17 is increased. Control is done. For this reason, even if the judgment level of the PM accumulation amount differs depending on the judgment method of the forced regeneration timing, the forced regeneration can be processed efficiently and appropriately with a combustion mode (combustion time and combustion temperature) that matches the PM accumulation amount at that time. Thus, it is possible to prevent deterioration of the fuel efficiency due to excessive forced regeneration and deterioration of the filter and catalyst due to abnormal combustion of the accumulated PM.

  Specifically, the target temperature (forced regeneration temperature Treg) of the temperature raising control 2 is set lower as the assumed amount of PM deposition increases, so that abnormal combustion of the deposited PM is prevented and forced regeneration is efficiently performed. It can be controlled properly. In addition, the deviation between the actual value and the estimated value of the PM accumulation amount is corrected by the regeneration process based on the forced regeneration interval and the regeneration process based on the zero reset forced regeneration interval. It can be maintained at a high level.

  For post-injection of temperature rise control 2, the basic injection amount is determined from the forced regeneration temperature Treg, the exhaust temperature, and the exhaust flow rate. When the fuel property changes, the temperature rise characteristic of the DPF 21 may change. To cope with this, the adjustment coefficient K for correcting the post injection amount is set to be changeable. Post injection amount = basic injection amount X Controlled by adjustment factor K.

  FIG. 4 is a flowchart for explaining the adjustment coefficient K changing process. In S1, it is determined whether the engine is operating. In S2, it is determined whether forced regeneration is in progress. In S3, it is determined whether the temperature raising control 2 is in progress. If the determination of S1 is yes, the determination of S2 is yes, and the determination of S3 is yes, the process proceeds to S4. If the determination of S1 is no or S2 is no or the determination of S3 is no, a return is reached.

  In S4, the moving average value Tave of the DPF temperature is calculated. In S5, it is determined whether or not Tave <regeneration start temperature Ts1 (temperature condition that satisfies PM combustion amount> PM emission amount). When the determination of S5 is yes, the process proceeds to S6, and when the determination of S5 is no, the process proceeds to S9. In S6, the elapsed time (t) of the non-reference temperature (Tave <Ts1) is counted. In S7, it is determined whether t ≧ reference time t1. If the determination of S7 is yes, the process proceeds to S8, while if the determination of S7 is no, a return is reached. That is, in S5 to S7, it is determined whether or not the elapsed time t of the non-reference temperature at which the moving average value Tave of the exhaust temperature is lower than the regeneration start temperature Ts1 reaches the reference time t1, and when this determination is yes Since it is determined that the temperature rise due to post injection is insufficient, the adjustment coefficient K is changed to the larger side in S8.

  In S9, it is determined whether Tave> forced regeneration temperature Treg. If the determination in S9 is yes, the process proceeds to S10, while if the determination in S9 is no, a return is reached. In S10, the elapsed time (t) of the non-reference temperature (Tave ≧ Treg) is counted. In S11, it is determined whether t ≧ reference time t2. When the determination of S11 is yes, the process proceeds to S8, while when the determination of S11 is no, a return is reached. That is, in S9 to S11, it is determined whether or not the elapsed time t of the non-standard temperature at which the moving average value Tave of the DPF temperature exceeds the forced regeneration temperature Treg reaches the reference time t2, and when this determination is yes Since it is determined that the temperature rise due to post injection is excessive, the adjustment coefficient K is changed to a smaller side in S8.

  In S8, an adjustment coefficient K corresponding to Tave is obtained from an adjustment coefficient map (see FIG. 5) set as a parameter based on the moving average value Tave of the DPF temperature, and is adjusted by multiplying the basic injection amount of post injection. The setting of the coefficient K is changed.

  In such a process, even if the fuel properties change, the adjustment factor K is changed to prevent excessive or insufficient temperature rise due to post injection (addition of fuel into the cylinder), and the DPF temperature is made higher than the regeneration start temperature Ts1. And it can be maintained in a suitable temperature environment below the forced regeneration temperature Treg. The adjustment coefficient K corresponds to the fuel property, and not only the post injection amount but also the main injection amount (including the after injection amount) is applied for correction according to the fuel property. Become.

  In FIG. 4, S5 to S6 or S9 to S11 are repeated in the temperature raising control 2, and the change of S8 may be repeated. Therefore, the means for measuring the number of times the change of S8 is repeated, the predetermined number of times It is desirable to provide means for prohibiting over-repetition, and means for stopping the forced regeneration and warning the suspension when the determination of S6 or S11 becomes yes after a predetermined number of changes. As a result, wasteful consumption of fuel can be suppressed, and appropriate measures (such as changing the fuel) can be promoted by an alarm. In FIG. 5, the reference adjustment coefficient K = 1 is an adjustment coefficient for pure light oil.

  As another embodiment corresponding to the change in fuel properties, an adjustment coefficient map (see FIG. 6) corresponding to the calorific value for each fuel type is set, while the intake flow rate (intake air amount) and the exhaust gas during normal operation. The fuel supply weight is obtained from the air-fuel ratio, the heat generation amount of the fuel is obtained from the fuel supply weight and the exhaust temperature, the fuel type is estimated from the heat generation amount, and the corresponding adjustment coefficient K (for example, the fuel type A is set to the fuel type A). It is also conceivable to obtain a corresponding adjustment coefficient Ka) and correct the fuel injection amount including the temperature increase control 2 by this adjustment coefficient K.

  The target of the temperature raising control 2 is not limited to post injection, and a device for adding fuel to the exhaust passage upstream of the CR-DPF 17 can also be set. In addition to the preheating means described above, the target for the temperature raising control 1 can also use a device for forcibly increasing the engine load (retarder brake or engine-driven accessories).

It is a schematic diagram explaining the structure of a system. It is a flowchart explaining the control content of a control unit. It is a flowchart explaining the control content of a control unit. It is a flowchart explaining the control content of a control unit. It is a characteristic view which illustrates an adjustment coefficient map. It is a characteristic view which illustrates another adjustment coefficient map. It is a characteristic view explaining the control content of a control unit.

Explanation of symbols

10 Diesel Engine 11 Intake Passage 12 Turbocharger 14 Intake Throttle Valve 15 Exhaust Passage 16 Exhaust Throttle Valve 17 CR-DPF (Continuous Regenerative Filter Device)
18 EGR valve 19 Turbo bypass valve 20 Control unit 21 DPF (CSF)
22 DOC
23 Differential pressure sensor 24-26 Temperature sensor 27 Air flow sensor

Claims (6)

  In an exhaust purification system that burns PM accumulated in the filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, means for estimating the amount of PM accumulated in the filter, whether a predetermined forced regeneration condition is satisfied The means for determining, the means for setting the forced regeneration temperature and the forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and the catalyst at the activation temperature when the satisfaction of the forced regeneration condition is determined. Means for controlling the amount of fuel added to the cylinder or the catalyst so as to maintain the filter temperature at the forced regeneration temperature when the value is lower than the lower limit value, and multiplying the control amount by an adjustment coefficient to correspond to the change in fuel properties. Means for adjusting the adjustment coefficient used for this correction, means for measuring the elapsed time of the non-reference temperature at which the filter temperature falls below the regeneration start temperature during control of the fuel addition amount, Exhaust purification device of the measuring time, characterized in that it comprises means, to change the larger side configuration with adjustment factor reaches a predetermined time.   In an exhaust purification system that burns PM accumulated in the filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, means for estimating the amount of PM accumulated in the filter, whether a predetermined forced regeneration condition is satisfied The means for determining, the means for setting the forced regeneration temperature and the forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and the catalyst at the activation temperature when the satisfaction of the forced regeneration condition is determined. Means for controlling the amount of fuel added to the cylinder or the catalyst so as to maintain the filter temperature at the forced regeneration temperature when the value is lower than the lower limit value, and multiplying the control amount by an adjustment coefficient to correspond to the change in fuel properties. Means for adjusting the adjustment coefficient used for the correction, means for measuring the elapsed time of the non-reference temperature at which the filter temperature exceeds the forced regeneration temperature during control of the fuel addition amount, Exhaust purification apparatus of measuring time, characterized in that it comprises means, for changing the small side configuration with adjustment factor reaches a predetermined time.   In an exhaust purification system that burns PM accumulated in the filter by the action of a catalyst while collecting PM contained in engine exhaust in the filter, means for estimating the amount of PM accumulated in the filter, whether a predetermined forced regeneration condition is satisfied The means for determining, the means for setting the forced regeneration temperature and the forced regeneration time according to the estimation of the PM accumulation amount when it is determined that the forced regeneration condition is satisfied, and the catalyst at the activation temperature when the satisfaction of the forced regeneration condition is determined. Means for controlling the amount of fuel added to the cylinder or the catalyst so as to maintain the filter temperature at the forced regeneration temperature when the value is lower than the lower limit value, and multiplying the control amount by an adjustment coefficient to correspond to the change in fuel properties. Means for adjusting the adjustment coefficient used for this correction, means for measuring the elapsed time of the non-reference temperature at which the filter temperature falls below the regeneration start temperature during control of the fuel addition amount, Means for changing the setting of the adjustment coefficient to the larger side when the measurement time of the engine reaches a predetermined time, means for measuring the elapsed time of the non-standard temperature at which the filter temperature exceeds the forced regeneration temperature during control of the fuel addition amount, and this measurement time Means for changing the setting of the adjustment coefficient to a smaller side when the time reaches a predetermined time.   The exhaust purification device according to any one of claims 1 to 3, wherein the adjustment coefficient is changed to a setting corresponding to a moving average value of the filter temperature.   A means for measuring the number of times the adjustment coefficient change is repeated, a means for prohibiting repetition exceeding the predetermined number of times, and after the predetermined number of changes, the forced regeneration is stopped when the elapsed time of the non-reference temperature reaches a predetermined time and the cancellation The exhaust emission control device according to any one of claims 1 to 4, further comprising a warning unit.   When it is determined that the forced regeneration condition is satisfied, there is provided means for positively increasing the exhaust temperature so as to raise the catalyst temperature above the lower limit value of the activation temperature when the catalyst temperature falls below the lower limit value of the activation temperature. The exhaust emission control device according to any one of claims 1 to 5, wherein: