JP4449678B2 - Diesel engine particulate accumulation estimation device and exhaust aftertreatment device - Google Patents

Description

  The present invention relates to a particulate matter accumulation amount estimation device and an exhaust aftertreatment device of a diesel engine.

In order to process exhaust particulates discharged from diesel engines, a filter that collects particulates is placed in the exhaust system, and when a predetermined amount of particulates is deposited on the filter, the filter temperature is raised and deposited on the filter. Various types of so-called filter regeneration processes have been proposed (see Patent Document 1).
JP-A-8-109818

  By the way, in order to calculate the particulate accumulation amount on the filter, first particulate accumulation amount estimation means for calculating (estimating) the particulate accumulation amount based on the pressure loss of the filter, and the particulate matter based on the traveling history of the vehicle. Second particulate accumulation amount estimation means for calculating the accumulation amount, and in the region where the actual vehicle speed detected by the vehicle speed sensor is less than or equal to the switching vehicle speed, the second particulate accumulation amount estimation means works, and the actual vehicle speed is When the region exceeds the switching vehicle speed, the first particulate accumulation amount estimation means is activated, and whether or not the filter regeneration time has come based on the particulate accumulation amount calculated by the first or second particulate accumulation amount estimation means There is a thing to judge. This is because the first particulate accumulation amount estimation means is higher in the accuracy of estimating the particulate accumulation amount than the second particulate accumulation amount estimation means. However, an error dependent on the vehicle speed occurs in the differential pressure sensor, which is particularly low. Since the estimation error becomes large in the vehicle speed range, a switching vehicle speed is provided in advance, and the second particulate accumulation amount estimation means is made to work in a region where the vehicle speed is equal to or lower than the switching vehicle speed.

  However, recent experiments have shown that the differential pressure sensor has an estimation error that also depends on the ambient temperature. Explaining this, FIG. 4 is an experimental result summarizing what the estimation error of the particulate deposition amount generated in the differential pressure sensor when the atmospheric temperature of the differential pressure temperature sensor is made different. As described above, in the low temperature range where the atmospheric temperature of the differential pressure sensor is equal to or lower than a first predetermined value TLIML (for example, 0 ° C.) and the high temperature range where the atmospheric temperature of the differential pressure sensor is equal to or higher than a second predetermined value TLIMU, The estimation error is larger than the temperature range.

  Therefore, even in such a low temperature range or high temperature range, if the switching vehicle speed remains at the switching vehicle speed for other temperature ranges, the estimated value of the particulate accumulation amount is affected by the estimation error generated in the differential pressure sensor. If it is smaller, the filter carrier will be excessively heated during the regeneration process, and the durability of the filter will deteriorate. On the contrary, when the estimated value of the particulate accumulation amount becomes larger than the actual value, the regeneration process is frequently performed (the regeneration process interval is short), which causes a deterioration in fuel consumption.

  Accordingly, the present invention provides an apparatus for improving the durability and fuel consumption of a filter carrier during regeneration processing so that the estimation error of the particulate deposition amount does not increase even if the atmospheric temperature of the differential pressure sensor is different. With the goal.

The present invention includes a filter that collects and deposits particulates in exhaust gas, and first particulate accumulation amount estimation means that estimates the particulate accumulation amount based on the pressure loss of the filter detected by the pressure loss detection means. A second particulate accumulation amount estimating means for estimating a particulate accumulation amount based on a travel history of the vehicle, detecting a temperature of the pressure loss detection means, and based on the detected temperature, It switched to either Tikyureto deposit amount estimating means, configured to so as to start reproduction processing based have been the filter particulate matter deposit amount estimated by the accumulated particulate quantity estimating means of the switched side Yes.

  As shown in FIG. 4, the temperature of the differential pressure sensor is estimated from a temperature range other than the low temperature range where the temperature is lower than the first predetermined value TLIML and the high temperature range where the temperature of the differential pressure sensor is higher than the second predetermined value TLIMU. In response to newly finding that the error has increased, according to the first aspect of the invention, one of the two particulate accumulation amount estimation means is switched based on the detected temperature Ts. Specifically, when the atmospheric temperature of the pressure loss detection means is in a low temperature range below the first predetermined value or when the atmospheric temperature of the pressure loss detection means is in a high temperature range above the second predetermined value, the vehicle speed is low. Since the switching from the second particulate accumulation amount estimation means side to the first particulate accumulation amount estimation means side is delayed when rising from the state, the particulate accuracy estimation accuracy in the low temperature region and the high temperature region is delayed. This can improve the durability and fuel consumption of the filter carrier during the regeneration process. In other words, if the estimated value of the particulate deposition amount is smaller than the actual value, the filter carrier will be excessively heated during the regeneration process and the durability will deteriorate, and conversely, the estimated value of the particulate deposition amount will be the actual value. When the number is increased, the regeneration process is frequently performed (the interval of the regeneration process is short), and the fuel consumption is deteriorated. However, such a situation can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

  In FIG. 1, 1 is a diesel engine, 2 is an intake passage, and 3 is an exhaust passage. The exhaust passage 3 includes a filter 4 that collects particulates in the exhaust. When the collected amount (deposition amount) of the particulates of the filter 4 reaches a predetermined value, the exhaust temperature is raised and the particulates are burned and removed.

  In order to detect the pressure loss of the filter 4 (pressure difference between the upstream and downstream of the filter 4), a differential pressure sensor 12 (pressure loss detection means) is provided in a differential pressure detection passage that bypasses the filter 4.

  The pressure loss of the filter 4 detected by the differential pressure sensor 12 includes the rotational speed from the engine rotational speed sensor 13, the accelerator opening from the accelerator sensor 14 (depressing amount of the accelerator pedal), and the intake air flow rate from the air flow meter 15. At the same time, the engine controller 11, which is mainly composed of a microprocessor, performs fuel injection control and regeneration processing of the filter 4 based on these.

  In the fuel injection control, the maximum injection amount is determined according to the cylinder intake air amount calculated from the output of the air flow meter 15 and the engine rotational speed in order to prevent smoke that occurs frequently near the full load. The corresponding basic fuel injection amount is limited by the maximum injection amount, and the fuel injection amount after the limitation is used at an optimal time using a fuel injection device (for example, a common rail type injection device including the supply pump 5, the common rail 6, and the injector 7). Spray.

  In the regeneration process of the filter 4, the particulate accumulation amount on the filter 4 is calculated (estimated), compared with a predetermined value, and when the particulate accumulation amount exceeds the predetermined value, the regeneration process of the filter 4 is performed. To start. That is, it starts by raising the exhaust gas temperature by delaying the injection timing of the fuel injected from the fuel injection device than usual, or by performing another injection (post injection) after the normal injection.

  In this case, in order to calculate the particulate deposition amount, the first particulate deposition amount estimation means for calculating the particulate deposition amount based on the pressure loss of the filter 4 and the particulate deposition amount based on the traveling history of the vehicle. Two particulate accumulation amount estimation means and a second particulate accumulation amount estimation means to be calculated are provided.

  On the premise of such an engine that performs the regeneration processing of the filter 41, the present invention includes a temperature sensor 18 (temperature detection means) that detects the temperature of the differential pressure sensor 12, for example, the ambient temperature, and based on the detected ambient temperature. Switch to one of the two particulate accumulation amount estimation means, and determine whether the regeneration timing of the filter 4 has come based on the particulate accumulation amount calculated by the particulate accumulation amount estimation means on the switched side To do.

  This control executed by the engine controller 11 will be described in detail with reference to the flowchart of FIG.

  FIG. 2 is used to calculate (estimate) the particulate accumulation amount of the filter 4 and is executed at regular intervals (for example, every 10 ms).

  In step 1, the ambient temperature Ts of the differential pressure sensor 12 detected by the temperature sensor 18 and the vehicle speed VSP detected by the vehicle speed sensor 17 (vehicle speed detection means) are read.

  In step 2, a table having the contents shown in FIG. 3 is retrieved from the differential pressure sensor ambient temperature Ts to switch between the calculation of the particulate deposition amount based on the pressure loss of the filter 4 and the calculation of the particulate deposition amount based on the running history. A switching vehicle speed Vtr which is a vehicle speed is calculated. As shown in FIG. 3, the switching vehicle speed Vtr becomes larger than the predetermined vehicle speed b as the temperature of the differential pressure sensor ambient temperature Ts becomes lower in a low temperature region where the temperature is lower than a first predetermined value TLIML (for example, 0 ° C. to −30 ° C.). The pressure sensor atmospheric temperature Ts is a value that becomes higher than the predetermined vehicle speed b as the temperature becomes higher in a high temperature range equal to or higher than the second predetermined value TLIMU. On the other hand, when the differential pressure sensor ambient temperature Ts is in a temperature range exceeding the first predetermined value TLIML and lower than the second predetermined value TLIMU, the switching vehicle speed Vtr is constant at the predetermined vehicle speed b.

  As described above, the vehicle speed at which the differential pressure sensor ambient temperature Ts is switched between the low temperature range where the first predetermined value TLIML is lower than the first predetermined value TLIML and the high temperature range where the differential pressure sensor ambient temperature Ts is higher than the second predetermined value TLIMU. Vtr is increased (increased) when the differential pressure sensor ambient temperature Ts is equal to or lower than the first predetermined value TLIML and the differential pressure sensor ambient temperature Ts is the second predetermined value as shown in FIG. This is because the estimation error of the particulate deposition amount based on the differential pressure sensor 12 becomes large in a high temperature range equal to or higher than TLIMU. In other words, the first predetermined value TLIML is the lower limit value of the appropriate temperature range of the differential pressure sensor 12, and the second predetermined value TLIMU is the upper limit value of the appropriate temperature range of the differential pressure sensor 12. FIG. 4 shows experimental results, and it is currently unknown why the maximum estimation error occurs in the low temperature range and the high temperature range of the differential pressure sensor ambient temperature.

  Further, FIG. 4 shows the gradient of the error of the differential pressure sensor almost symmetrically in the low temperature range and the high temperature range of the differential pressure sensor atmosphere temperature. However, the present invention is not limited to this, and as shown in FIG. There are some in which the differential pressure sensor has a different error slope between the low temperature range and the high temperature range of the differential pressure sensor (see the broken line and the alternate long and short dash line in FIG. 14). Further, in FIGS. 4 and 14, the slope of the error of the differential pressure sensor in the low temperature region and the high temperature region of the differential pressure sensor ambient temperature is shown by a straight line, but this is an approximation and is actually a downward convex curve.

  In step 3, the switching vehicle speed Vtr obtained in this way is compared with the actual vehicle speed VSP read in step 1. When the actual vehicle speed VSP is less than or equal to the switching vehicle speed Vtr, the routine proceeds to step 5 where the particulate accumulation amount is calculated based on the travel history. On the other hand, when the actual vehicle speed VSP exceeds the switching vehicle speed Vtr, from step 3 Proceeding to step 4, the particulate deposition amount based on the pressure loss of the filter 4 is calculated. The particulate accumulation amount calculation method based on the pressure loss of the filter 4 in the high vehicle speed range exceeding the switching vehicle speed Vtr is adopted because the particulates based on the pressure loss of the filter 4 increase as the exhaust flow rate increases at a high vehicle speed as shown in FIG. This is because the estimation accuracy of the curate deposition amount is improved. The characteristics of FIG. 5 are known, and the difference between the two curves in FIG. 5 means the width of variation.

  A known method may be used for the calculation of the particulate deposition amount based on the travel history and the calculation of the particulate deposition amount based on the pressure loss of the filter 4. For example, from the calculation of the particulate accumulation amount based on the travel history, the engine controller 11 is provided with a particulate discharge map (particulate discharge amount per unit time under each operating condition) as shown in FIG. The map is searched for each unit time to obtain a particulate discharge amount per unit time, and a value obtained by accumulating the particulate discharge amount according to the following equation is obtained as a particulate deposition amount SUMPM1.

SUMPM1 = SUMPM1 (previous) + ΔPM (1)
Where ΔPM: particulate discharge per unit time,
SUMPM1 (previous): previous particulate deposition amount,
The calculation of the particulate accumulation amount due to the pressure loss of the filter 4 basically utilizes the fact that the particulate accumulation amount is expressed as a function of the volume flow rate of the exhaust gas flowing through the filter 4 and the pressure loss before and after the filter 4. It is. Specifically, the characteristic as shown in FIG. 7 is given, and this table is searched from the pressure loss of the filter 4 to calculate the particulate accumulation amount SUMPM2.

  Although not shown, when the vehicle speed VSP increases and crosses the switching vehicle speed Vtr, the particulate accumulation amount SUMPM1 based on the travel history of the vehicle is reset to zero at the timing when the vehicle speed VSP crosses the switching vehicle speed Vtr. Conversely, when the vehicle speed VSP decreases and crosses the switching vehicle speed Vtr, the particulate accumulation amount SUMPM2 based on the pressure loss of the filter 4 immediately before the timing when the vehicle speed VSP crosses the switching vehicle speed Vtr is expressed by the above equation (1). In the first term on the right side, the particulate accumulation amount SUMPM1 is calculated based on the travel history of the vehicle.

  In step 6, it is determined whether or not the engine is stopped. If the engine is not stopped, the process returns to step 1 and the above operation is repeated. If the engine is stopped, the process is terminated.

  The particulate deposition amounts SUMPM1 and SUMPM2 calculated in this way are used to determine whether or not to start the filter regeneration process in the flow of the filter regeneration process (not shown). That is, when the particulate accumulation amount SUMPM1 exceeds a predetermined value in a region where the vehicle speed VSP is equal to or lower than the switching vehicle speed Vtr, or when the particulate deposition amount SUMPM2 exceeds a predetermined value in a region where the vehicle speed VSP exceeds the switching vehicle speed Vtr. It is determined that it is time to start the regeneration process of the filter 4 respectively, and the regeneration process of the filter 4 is performed.

  Here, the effect of this embodiment is demonstrated, referring FIG. In this case, the conventional device (see the one-dot chain line in FIG. 3) is used in which the switching vehicle speed Vtr is set to a constant value b regardless of the differential pressure sensor ambient temperature Ts.

  FIG. 8 shows acceleration in the low temperature region where the differential pressure sensor 12 ambient temperature Ts is equal to or lower than the first predetermined value TLIML (for example, when the differential pressure sensor ambient temperature Ts is the predetermined value c [° C.] shown in FIG. 3). It shows how the amount of particulate deposition is estimated when is raised as shown in the figure.

  In the low vehicle speed range where the actual vehicle speed VSP is equal to or lower than the switching vehicle speed Vtr, the particulate accumulation amount is estimated based on the travel history of the vehicle, and the estimated particulate accumulation amount at this time is the true particulate accumulation amount (see FIG. 8). (Refer to the thin solid line), and has a certain width as shown by the two upper and lower thick solid lines. When the upper thick solid line has the largest estimation error, the lower thick solid line has the smallest estimation error. It is an estimated value of each particulate deposition amount when there is.

  When the actual vehicle speed VSP rises to a constant value b, according to the conventional apparatus, the switching vehicle speed Vtr is constant b regardless of the differential pressure sensor atmospheric temperature Ts, and therefore particulate accumulation based on the running history of the vehicle from time t1. Since the estimation of the amount of particulate deposition based on the pressure loss is switched from the estimation of the amount to the estimation of the particulate deposition amount based on the pressure loss of the filter, the estimated value of the particulate deposition amount at this time by the conventional apparatus is Particulate deposition when there is a certain width as shown by the upper and lower two-dot chain lines, and when the upper one-dot chain line has the largest estimation error and the lower one-dot chain line has the smallest estimation error It can be seen that there is a large estimation error when the vehicle speed is close to the constant value b.

  On the other hand, according to the present embodiment, when the differential pressure sensor ambient temperature Ts is in a low temperature range equal to or lower than the first predetermined value TLIML, the switching vehicle speed Vtr increases from the constant value b to the predetermined value d (see FIG. 3). Therefore, at the time t1, the estimation of the particulate accumulation amount based on the traveling history of the vehicle is not switched to the estimation of the particulate accumulation amount based on the pressure loss of the filter. That is, the particulate accumulation amount is continuously estimated based on the travel history of the vehicle during the period A from time t1 to time t2. At this time, the estimated amount of particulate accumulation has a certain width as shown by the upper and lower thick solid lines, and when the upper thick solid line has the largest estimation error, the lower thick solid line is Each estimated value of the particulate deposition amount when there is a minimum estimation error. That is, in the period A in which the switching speed Vtr is increased from the constant value b on the basis of the differential pressure sensor ambient temperature Ts, the present embodiment indicated by the thick solid line is more efficient than the conventional device indicated by the alternate long and short dash line. The estimation error of the curate deposition amount is small.

  The estimation of the particulate deposition amount from the time t2 is the same for both the conventional apparatus and the present embodiment, and the particulate deposition amount is estimated based on the pressure loss of the filter 4.

  The broken line in the period after time t2 shows the estimated value of the particulate accumulation amount when the estimation of the particulate accumulation amount based on the travel history is continued after t2, for reference, and the high vehicle speed exceeding the switching vehicle speed d In the region, the estimation accuracy of the particulate accumulation amount based on the pressure loss of the filter 4 is higher than the estimation accuracy of the particulate accumulation amount based on the traveling history.

  As described above, according to the present embodiment (the invention described in claim 1), based on the atmospheric temperature Ts of the differential pressure sensor 12, the calculation of the particulate accumulation amount based on the pressure loss of the filter 4 and the travel history of the vehicle are performed. The calculation is switched to one of the calculation of the particulate deposition amount based on one of the two particulate deposition amount estimation means. Specifically, when the differential pressure sensor atmosphere temperature Ts is in a low temperature range below the first predetermined value TLIML, or when the differential pressure sensor atmosphere temperature Ts is in a high temperature range above the second predetermined value TLIMU, the vehicle speed is low. Calculation of the particulate accumulation amount based on the pressure loss of the filter (first particulate) from the calculation of the particulate accumulation amount based on the running history of the vehicle (on the side of the second particulate accumulation amount estimation means) when rising from the state. The delay in switching to the accumulation amount estimation means side), so that the estimation accuracy of the particulates in the low temperature region below the first predetermined value TLIML and the high temperature region above the second predetermined value TLIMU is not reduced. This can improve the durability and fuel consumption of the filter carrier during the regeneration process. That is, if the estimated value of the particulate deposition amount is smaller than the actual value, the carrier of the filter 4 is excessively heated during the regeneration process and the durability deteriorates. Conversely, the estimated value of the particulate deposition amount is actually reduced. When the value exceeds the value, the regeneration process of the filter 4 is frequently performed (the regeneration process interval is short), which causes a deterioration in fuel consumption. Such a situation can be avoided.

  The temperature sensor 18 for detecting the ambient temperature of the differential pressure sensor 12 is not necessarily provided near the differential pressure sensor 12, and an intake air temperature sensor provided in the air cleaner can be substituted.

  The flowchart of FIG. 9 is the second embodiment, which replaces FIG. 2 of the first embodiment. The same steps as those in FIG. The flow in FIG. 9 is also executed at regular time intervals (for example, every 10 ms).

  Prior to the description of FIG. 9, differences from the first embodiment will be described first. In the method for calculating the particulate accumulation amount based on the travel history of the vehicle, as shown in FIG. 11, the particulate deposition increases as the continuous travel distance SUML from the start of the calculation of the particulate deposition amount based on the travel history of the vehicle increases. It is known that the estimation error of quantity becomes large. This is because the particulate accumulation calculation method based on the running history of the vehicle searches the map as shown in FIG. 6 for each unit time to obtain the particulate discharge amount per unit time, and integrates this to calculate the particulate amount. This is because the configuration is such that the amount of curate deposition is obtained, and therefore the estimation error that occurs in the calculation of the particulate discharge amount per unit time is gradually accumulated.

  Therefore, in the fourth embodiment, the method for calculating the particulate accumulation amount based on the pressure loss of the filter 4 according to the continuous travel distance SUML after the calculation of the particulate accumulation amount based on the travel history of the vehicle is started. By changing the switching vehicle speed for switching, the estimation error of the particulate accumulation amount is prevented from becoming large even when the calculation of the particulate accumulation amount based on the running history of the vehicle is continuously performed for a long time.

  Specifically, as shown in FIG. 12, the area of the particulate deposition amount estimation error based on the travel history of the vehicle is defined as an area less than the first estimation error E0, a first estimation error E0 or more, and a second estimation error. The first estimation error E0 that defines the boundary between the four areas is divided into four areas: an area less than E1, an area greater than the second estimation error E1 and less than the third estimation error E2, and an area greater than the third estimation error E2. The continuous travel distances corresponding to the second estimation error El and the third estimation error E2 are defined as a first travel distance L0, a second travel distance L1, and a third travel distance L2, respectively.

  When the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is a continuous travel distance section less than the first travel distance L0, the particulate deposition based on the pressure loss of the filter 4 Switching to switch to the particulate deposition amount calculation method based on the pressure loss of the filter 4 so that the estimation error of the particulate deposition amount when the amount calculation method is used is suppressed to the first estimation error E0 or less. The vehicle speed characteristic is set (see the solid line in FIG. 13). The characteristic of the switching vehicle speed for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 shown by the solid line in FIG. 13 is defined as “characteristic 0”, and this continuous travel distance section (characteristic 0 section) ), In accordance with this characteristic 0, the method switches to a method for calculating the particulate deposition amount based on the pressure loss of the filter 4.

  Actually, the characteristic 0 is the same as that of FIG. 3 of the first embodiment. That is, when the continuous travel distance SUML from the start of calculation of the particulate accumulation amount based on the travel history of the vehicle is a continuous travel distance section that is less than the first travel distance L0, the filter 4 is compared with the first embodiment. The switching vehicle speed for switching to the calculation method of the particulate accumulation amount based on the pressure loss is not changed. At this time, the particulate deposition amount estimation error when switching to the particulate deposition amount calculation method based on the pressure loss of the filter 4 and the particulate deposition amount calculation method based on the running history of the vehicle are continued. This is because the estimation error of the accumulation amount is equivalent to the estimation error of the accumulation amount, so that the estimation error does not become small even when the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 is switched. In other words, the continuous travel distance section in which the continuous travel distance SUML is less than the first travel distance L0 is a section like a dead zone.

  Next, when the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is a continuous travel distance section of the first travel distance L0 or more and less than the second travel distance L1, the filter 4 To the calculation method of the particulate deposition amount based on the pressure loss of the filter 4 so that the error when estimated using the calculation method of the particulate deposition amount based on the pressure loss of the filter 4 is suppressed to the second estimation error E1 or less. The characteristic of the switching vehicle speed for switching is set (refer to the one-dot chain line in FIG. 13). The characteristic of the switching vehicle speed for switching to the method of calculating the particulate accumulation amount based on the pressure loss of the filter 4 indicated by the one-dot chain line in FIG. 13 is defined as “characteristic 1”, and this continuous travel distance section (characteristic 1 In the section), according to the characteristic 1, the method is switched to the calculation method of the particulate accumulation amount due to the pressure loss of the filter 4.

  Similarly, when the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is a continuous travel distance section of the second travel distance L1 or more and less than the third travel distance L2, the filter 4 to the calculation method of the particulate deposition amount based on the pressure loss of the filter 4 so that the error when estimated using the calculation method of the particulate deposition amount due to the pressure loss of 4 is suppressed to the third estimation error E2 or less. The characteristic of the switching vehicle speed for switching is set (see the broken line in FIG. 13). The characteristic of the switching vehicle speed for switching to the method of calculating the particulate accumulation amount based on the pressure loss of the filter 4 shown by the broken line in FIG. 13 is defined as “characteristic 2”, and this continuous travel distance section (characteristic 2 section) ), In accordance with the characteristic 2, the method is switched to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4.

  More specifically, according to the first embodiment, the vehicle speed region between the characteristics 0 and 2 in FIG. 13 is also an area that uses the method for calculating the particulate accumulation amount based on the travel distance of the vehicle. In the fourth embodiment, even if the vehicle speed VSP is in the low vehicle speed region defined by the characteristics 0 and 1, the continuous travel distance from the start of calculating the particulate accumulation amount based on the travel history of the vehicle is When entering the characteristic 1 section, the method is switched to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4, and even if the vehicle speed VSP is in the vehicle speed region on the lower vehicle speed side defined by the characteristics 1 and 2. When the continuous travel distance from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is prolonged to reach the characteristic 2 section, the particulate based on the pressure loss of the filter 4 It is intended to switch to the calculation method of the preparative deposit amount.

  Thus, when the continuous travel distance SUML from the start of calculation of the particulate accumulation amount based on the travel history of the vehicle is in the continuous travel distance section of the first travel distance L0 or more and less than the third travel distance L2, The switching vehicle speed for switching from the characteristic 0 to the characteristic 1 and from the characteristic 1 to the characteristic 2 step by step to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 is lowered for the following reason. is there. That is, when the particulate deposition amount estimation error when switching to the particulate deposition amount calculation method based on the pressure loss of the filter 4 depending on the vehicle speed and the particulate deposition amount calculation method based on the running history of the vehicle are continued. When the particulate deposition amount estimation error is switched to the calculation method of the particulate deposition amount based on the pressure loss of the filter 4, the particulate deposition amount estimation error is based on the running history of the vehicle. This is because it has been found through experiments that the calculation error of the amount of accumulated particulates can be made relatively smaller than the estimation error of the amount of particulate accumulation.

  Further, when the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle becomes equal to or greater than the third travel distance L2, the particulate deposition amount based on the pressure loss of the filter 4 is increased. The switching vehicle speed for switching to the calculation method is not further reduced. At this time, the particulate deposition amount estimation error when switching to the particulate deposition amount calculation method based on the pressure loss of the filter 4 and the particulate deposition amount calculation method based on the running history of the vehicle are continued. Since the estimation error of the deposition amount becomes equal and the estimation error of the particulate deposition amount is not reduced even when the calculation method of the particulate deposition amount based on the pressure loss of the filter 4 is switched, the particulate deposition based on the pressure loss of the filter 4 is not reduced. This is because it makes no sense to switch to the amount calculation method.

  In the embodiment, the switching vehicle speed for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 including the characteristic 0 is provided, but is not limited thereto. There should be at least two switching vehicle speeds (characteristic 0 and characteristic 1) for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 including the characteristic 0. Moreover, it is not limited to what reduces the switching vehicle speed for switching to the calculation method of the particulate deposition amount based on the pressure loss of the filter 4 in steps. The switching vehicle speed for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 may be lowered steplessly as the continuous travel distance SUML becomes longer.

  This completes the description of the difference from the first embodiment.

  In FIG. 9, the difference from the first embodiment will be mainly described. In step 11, the flag FSO (initially set to zero) is seen. This flag FSO becomes FSO = 1 when calculating the particulate accumulation amount based on the running history of the vehicle as will be described later in steps 19 and 20, and the particulate accumulation amount is calculated based on the pressure loss of the filter 4. This flag is set so that FSO = 0 when performing.

  When the flag FSO = 1, it is determined that the particulate accumulation amount is calculated based on the travel history of the vehicle, and the process proceeds to step 12 to calculate the particulate deposition amount based on the travel history of the vehicle. The continuous running distance SUML after the start is read. The calculation of the continuous travel distance SUML after the calculation of the particulate accumulation amount based on the travel history of the vehicle will be described with reference to the flow of FIG. The flow of FIG. 10 is executed prior to the flow of FIG.

  In FIG. 10, in steps 31 and 32, it is checked whether or not the flag FSO = 1 at this time, and whether or not the flag FSO = 1 was last time. The flag FSO = 1 at this time and the flag FSO = 0 at the previous time, that is, from the calculation of the particulate accumulation amount based on the pressure loss of the filter 4 for the first time to the calculation of the particulate accumulation amount based on the running history of the vehicle. When switched, the routine proceeds to step 33, where the continuous travel distance SUML is initialized to zero.

  When the flag FSO = 1 and the flag FSO = 1 last time, that is, when the calculation of the particulate accumulation amount based on the traveling history of the vehicle is continued, the process proceeds from step 31 and step 32 to step 34. Thus, the continuous travel distance SUML after the calculation of the particulate accumulation amount based on the travel history of the vehicle is calculated.

SUML = SUML (previous) + ΔL (2)
Where ΔL: mileage per fixed time,
SUML (previous): continuous mileage up to the previous time,
In addition, when the calculation of the particulate accumulation amount based on the traveling history of the vehicle is continued and the calculation is switched to the calculation of the particulate accumulation amount based on the pressure loss of the filter 4, the flag FSO = 0. Proceeding from step 31 to step 35, the continuous running distance SUML = 0 is reset.

  As described above, when the calculation of the particulate accumulation amount based on the travel history of the vehicle is continuously performed, the accumulated travel distance ΔL per certain time is added up to thereby calculate the particulate accumulation amount based on the travel history of the vehicle. It is possible to calculate the continuous travel distance SUML after the calculation is started.

  Returning to FIG. 9, in steps 13, 14, and 15, the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle, the first travel distance L 0, and the second travel distance L 1. The third travel distance L2 is compared. When the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is less than the first travel distance L0, the routine proceeds from step 13 to step 16, and from the differential pressure sensor ambient temperature Ts, A switching vehicle speed Vtr for switching to a method for calculating the particulate accumulation amount based on the pressure loss of the filter 4 is calculated by searching a table of characteristic 0 (see solid line) shown in FIG.

  Similarly, when the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle is not less than the first travel distance L0 and less than the second travel distance L1, the steps 13 and 14 are performed. Proceeding to step 17, from the differential pressure sensor ambient temperature Ts, by searching the table of characteristic 1 shown in FIG. 13 (refer to the alternate long and short dash line), the calculation of the particulate accumulation amount based on the running history of the vehicle When the continuous travel distance SUML is greater than or equal to the second travel distance L1 and less than the third travel distance L2, the process proceeds from Steps 13, 14, and 15 to Step 18, and from the differential pressure sensor ambient temperature Ts, the characteristic 2 table shown in FIG. By searching for (see broken line), it is possible to switch to a method for calculating the particulate accumulation amount based on the pressure loss of the filter 4. The vehicle speed Vtr is calculated.

  In step 3, the actual vehicle speed VSP is compared with the switching vehicle speed Vtr for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter 4 thus calculated. When the vehicle speed is less than the switching vehicle speed Vtr for switching to the calculation method of the particulate accumulation amount based on the loss, the process proceeds from step 3 to step 5 to continue the calculation of the particulate accumulation amount based on the traveling history of the vehicle, and the actual vehicle speed VSP. When the vehicle speed becomes equal to or higher than the switching vehicle speed Vtr, the process proceeds from step 3 to step 4 to switch to calculation of the particulate accumulation amount based on the pressure loss of the filter 4. Further, when the calculation of the particulate accumulation amount based on the traveling history of the vehicle is continued, the flag FSO = 1 is set at step 20, and when the calculation is switched to the calculation of the particulate accumulation amount based on the pressure loss of the filter 4, at step 19. The flag FSO = 0.

  On the other hand, when the flag FSO = 0 in step 11 (when calculating the particulate accumulation amount based on the pressure loss of the filter 4), the process proceeds to step 2 as in the first embodiment, and the differential pressure sensor atmosphere The switching vehicle speed Vtr is calculated by searching a table having the contents shown in FIG. 3 from the temperature Ts. The subsequent steps are the same as in the first embodiment. That is, in steps 3 to 5, the actual vehicle speed VSP is compared with the switching vehicle speed Vtr thus calculated, and when the actual vehicle speed VSP is less than the switching vehicle speed Vtr, the particulate accumulation amount is calculated based on the travel history of the vehicle. When the actual vehicle speed VSP becomes equal to or higher than the switching vehicle speed Vtr, the particulate accumulation amount based on the pressure loss of the filter 4 is calculated. Further, when calculating the particulate accumulation amount based on the running history of the vehicle, the flag FSO = 1 is set at step 20, and when calculating the particulate accumulation amount based on the pressure loss of the filter 4, the flag FSO = 0 is set at step 19. To do.

As described above, according to the second embodiment (the invention described in claims 5 and 6 ), the continuous travel distance SUML (second particulate deposition after the calculation of the particulate deposition amount based on the travel history of the vehicle is started). A continuous travel distance in which the particulate accumulation amount is continuously estimated by the amount estimation means), and the filter is determined according to the continuous travel distance SUML after the calculation of the particulate deposition amount based on the travel history of the vehicle is started. The switching vehicle speed Vtr for switching to the particulate deposition amount calculation method based on the pressure loss of 4 (vehicle speed switched to the first particulate deposition amount estimation means) is changed.
More specifically, the switching vehicle speed for switching to the method for calculating the particulate accumulation amount based on the pressure loss of the filter 4 as the continuous travel distance SUML from the start of the calculation of the particulate accumulation amount based on the travel history of the vehicle increases. Since Vtr is lowered, the estimation error of the particulate accumulation amount can be kept low even when the continuous travel distance SUML after the calculation of the particulate accumulation amount based on the travel history of the vehicle is prolonged. .

  The function of the first particulate deposition amount estimation means according to claim 1 is performed by step 4 in FIG. 2, and the function of the second particulate deposition amount estimation means is performed by step 5 in FIG. This function is performed by step 3 and FIG. 3 in FIG.

The schematic block diagram which shows one Embodiment of this invention. The flowchart for demonstrating calculation of the particulate accumulation amount. The characteristic figure of switching vehicle speed. The characteristic view of the differential pressure sensor error with respect to the differential pressure sensor atmospheric temperature of 1st Embodiment. The characteristic figure of the differential pressure sensor error to vehicle speed. The characteristic figure of particulate discharge per unit time. The characteristic figure of the particulate accumulation amount with respect to the pressure loss of a filter. The wave form diagram which shows the effect | action of this embodiment in the low temperature range whose differential pressure sensor atmospheric temperature is near a limit. The flowchart for demonstrating calculation of the particulate deposition amount of 2nd Embodiment. The flowchart for demonstrating the calculation of the continuous travel distance of 2nd Embodiment. The characteristic view of the estimation error of the particulate accumulation amount based on the driving | running | working log | history of the vehicle of 2nd Embodiment. The characteristic view of the estimation error of the particulate accumulation amount based on the driving | running | working log | history of the vehicle of 2nd Embodiment. The characteristic figure of the switching vehicle speed for switching to the calculation method of the particulate accumulation amount based on the pressure loss of the filter of 2nd Embodiment. The characteristic view of the differential pressure sensor error with respect to the differential pressure sensor atmospheric temperature of other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 3 Exhaust passage 4 Filter 11 Engine controller 12 Differential pressure sensor (pressure loss detection means)
17 Vehicle speed sensor 18 Temperature sensor (temperature detection means)

Claims (7)

A filter that collects and deposits particulates in the exhaust;
Pressure loss detecting means for detecting the pressure loss of the filter;
First particulate deposition amount estimation means for estimating the particulate deposition amount based on the detected pressure loss of the filter;
Second particulate accumulation amount estimation means for estimating the particulate accumulation amount based on the travel history of the vehicle ;
Temperature detecting means for detecting the temperature of the pressure loss detecting means;
Based on this the detected temperature, the particulate matter deposit amount estimation means switching means for switching to either of the two paths Tikyureto deposit amount estimating means,
Processed diesel engine exhaust, characterized in that based on the particulate matter deposit amount estimated by the accumulated particulate quantity estimating means of the switched side with and a filter regeneration means for initiating the regeneration process of the filter apparatus. Furthermore, it has vehicle speed detection means for detecting the vehicle speed of the vehicle,
2. The exhaust of a diesel engine according to claim 1, wherein the particulate accumulation amount estimating means switching means switches to one of the two particulate accumulation amount estimating means based on the detected vehicle speed. Post-processing device. 3. The diesel engine exhaust according to claim 2, wherein a switching vehicle speed for switching to one of the two particulate accumulation amount estimating means is increased as the detected temperature is lower than a first predetermined value. Post-processing device. 4. The diesel engine according to claim 2, wherein a switching vehicle speed for switching to one of the two particulate accumulation amount estimation means is increased as the detected temperature rises from a second predetermined value. 5. Exhaust aftertreatment device. The switched-side particulate accumulation amount estimation means is the second particulate accumulation amount estimation means, and a continuous travel distance is calculated by continuously estimating the particulate accumulation amount by the second particulate accumulation amount estimation means. 5. The exhaust aftertreatment device for a diesel engine according to claim 4 , wherein a switching vehicle speed for switching to the first particulate accumulation amount estimating means is changed in accordance with the continuous travel distance. 6. The exhaust aftertreatment device for a diesel engine according to claim 5 , wherein a switching vehicle speed for switching to the first particulate accumulation amount estimation means is reduced as the continuous travel distance becomes longer. The exhaust aftertreatment device for a diesel engine according to any one of claims 1 to 6, wherein the temperature detecting means detects an atmospheric temperature of the pressure loss detecting means .

Images