JP2004190568A - Filter regeneration control device for diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter regeneration control device for a diesel engine capable of preventing degradation of DPF even if abnormal combustion of PM occurs due to accumulation of PM or uneven distribution of unburnt residue in the DPF. <P>SOLUTION: This device comprises a filter 11 which is provided at an exhaust system in the diesel engine 20, captures particulates in the exhaust gas, and burns the particulates collected at the regeneration timing of the filter and regenerates; a temperature measuring means 13 for measuring the temperature of the filter; a regenerative limit judgment means 16 for judging the limit of the filter regeneration based on temperature measured by the temperature measuring means during regeneration of the filter; and a regeneration control means 16 for controlling the filter regeneration based on the judgment of the regeneration limit judgment means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a filter regeneration control device that can prevent deterioration of a filter that reduces particulates discharged from a diesel engine.
[0002]
[Prior art]
As a countermeasure against black smoke of diesel engines, a filter (Diesel Particulate Filter, hereinafter abbreviated as "DPF") that traps particulate matter (Particulate Matter, hereinafter abbreviated as "PM") contained in exhaust gas is used. Has been adopted. In such a DPF, a filter is regenerated by burning the deposited PM at a timing when the PM has been deposited to some extent (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-7-34853
[Problems to be solved by the invention]
By the way, in the above-described conventional apparatus, a sensor for detecting a differential pressure of the DPF is provided by determining whether or not the timing at which PM has accumulated to some extent (regeneration time of the filter) or whether or not the regeneration of the filter has been completed. Judge from the sensor output.
[0005]
Such a method for determining the start and end of regeneration is based on the assumption that PM is uniformly deposited in the space within the DPF, and only on the assumption that all PM is burned uniformly within the DPF. Therefore, it is not possible to cope with the case where the PM deposition distribution inside the DPF is not uniform or the case where combustion does not progress evenly inside the DPF, and the durability of the filter may be impaired due to the presence of a spot which is hot in a spot. That is, in the case where the DPF has a cylindrical shape, the flow velocity of the exhaust gas flowing near the axis of the cylinder is high, and the flow velocity of the exhaust gas flowing near the outer circumference is low. Due to such a spatial deviation of the exhaust flow velocity, PM is not uniformly deposited in the DPF but is localized. In this way, if the PM with a non-uniform deposition distribution inside the DPF burns at the regeneration timing, the combustion speed and the amount of heat generated increase significantly in a portion where the PM deposition amount is larger than the others, and the DPF is thermally degraded. May occur. Also, if the PM that remains without being completely burned is burned at the next regeneration timing, the combustion speed and the amount of heat generated will increase at that point, which may also decrease the heat resistance of the DPF. There is.
[0006]
The present invention has been made in view of such a conventional problem. Even if abnormal combustion of PM occurs due to accumulation of PM in the DPF or uneven distribution of unburned residue, deterioration of the DPF is prevented. It is an object of the present invention to provide a diesel engine filter regeneration control device that does not generate any.
[0007]
[Means for Solving the Problems]
The present invention solves the above problem by the following means. Note that, for easy understanding, reference numerals corresponding to the embodiments of the present invention are given, but the present invention is not limited thereto.
[0008]
The present invention relates to a filter provided in an exhaust system of a diesel engine (20) to collect particulates in exhaust gas and to burn and regenerate the collected particulates at a filter regeneration timing. 11), a temperature measuring means (13) for measuring the temperature of the filter, and a regeneration restriction judging means (16) for judging a restriction on filter regeneration based on the temperature measured by the temperature measuring means during regeneration of the filter. ), And regeneration control means (16) for controlling the filter regeneration based on the judgment of the regeneration restriction judging means.
[0009]
[Action / Effect]
According to the present invention, it is determined whether or not there is uneven deposition of PM and unburned residue in the DPF, that is, whether or not abnormal combustion based on these is present, based on the filter temperature during filter regeneration and the differential pressure across the filter. When the abnormal combustion is occurring, the filter regeneration is restricted, so the filter temperature is excessively high due to the abnormal combustion based on the accumulation of PM in the DPF and the uneven distribution of the unburned residue during the filter regeneration. Can be prevented, and the performance can be maintained without deteriorating the performance of the filter.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings and the like.
[0011]
FIG. 1 is a diagram showing one embodiment of a filter regeneration control device for a diesel engine of the present invention.
[0012]
The DPF regeneration control device 10 includes a DPF 11, a differential pressure sensor 12, a DPF inlet temperature sensor 13, a DPF outlet temperature sensor 14, an A / F sensor 15, and an engine control unit 16.
[0013]
The DPF 11 is a filter for collecting PM in exhaust gas discharged from the diesel engine 20, and for example, a ceramic porous filter or the like can be used. The differential pressure sensor 12 is a pressure difference measuring unit that detects a differential pressure between the pressure on the inlet side of the DPF 11 and the pressure on the outlet side, and outputs a detected differential pressure signal to the engine controller. The DPF inlet temperature sensor 13 is a temperature measuring unit that detects the inlet temperature of the DPF 11, and outputs an inlet temperature signal to the engine controller. The DPF outlet temperature sensor 14 is a temperature measuring unit that detects the outlet temperature of the DPF 11, and outputs an outlet temperature signal to the engine controller. The A / F sensor 15 is a sensor that detects an air-fuel ratio of exhaust gas discharged from the diesel engine 20. Since the A / F sensor 15 only needs to be able to determine the stoichiometric air-fuel ratio, an O ₂ sensor may be used.
[0014]
The engine control unit 16 receives signals from the sensors 12 to 15 and estimates the PM combustion state in the DPF 11 based on the signals. When it is determined that excessive combustion of PM has occurred, the engine control unit 16 controls the throttle 21, the EGR 22, the injection 23, and the like of the diesel engine 20 to stop or suppress DPF regeneration. Specific control will be described later.
[0015]
FIG. 2 is a flowchart for explaining the operation of the filter regeneration control device for a diesel engine, centering on the operation of the engine control unit.
[0016]
Note that this control is repeatedly executed at regular small time intervals (for example, 10 msec).
[0017]
First, the engine control unit 16 determines whether or not the DPF 11 is being regenerated. If the DPF 11 is being regenerated, the process is started. If not, the process is not performed (step S1).
[0018]
In step S2, the engine control unit 16 determines whether or not the outlet temperature (TDPF_out) of the DPF 11 exceeds the allowable upper limit temperature (T0) of the DPF 11. When the outlet temperature (TDPF_out) of the DPF 11 exceeds the allowable upper limit temperature (T0) for maintaining the performance of the DPF 11, the regeneration of the DPF 11 is immediately stopped (Step S3). If not, the process proceeds to step S4.
[0019]
The reproduction stop mode in the step S3 is the PM combustion, a mode immediately stopped, for example, performs λ control (i.e., DPF inlet _{O 2} concentration control) the. Specifically, intake throttle, by performing the EGR control, reducing the DPF inlet _{O 2} concentration, or by a 0% to stop the PM combustion.
[0020]
In step S4, it is determined whether or not the outlet temperature (TDPF_out) of the DPF 11 and the inlet temperature (TDPF_in) of the DPF 11 exceed the PM combustion temperature (T1). If not, since abnormal combustion of PM has not occurred, the routine proceeds to step S10, and normal DPF regeneration is performed. If it exceeds, the process proceeds to step S5.
[0021]
In step S5, it is determined whether or not the value of the temperature difference (ΔT = TDPF_out−TDPF_in) between the outlet temperature (TDPF_out) of the DPF 11 and the inlet temperature (TDPF_in) of the DPF 11 is a positive value. When the value is a negative value, the outlet temperature is lower than the inlet temperature, so that abnormal combustion of PM has not occurred. Therefore, at this time, the process proceeds to step S10 to perform normal DPF regeneration. If it exceeds, the process proceeds to step S6.
[0022]
In step S6, it is determined whether or not the time differential value of the outlet temperature (TDPF_out) of the DPF 11 is larger than the value obtained by multiplying the time differential value of the inlet temperature (TDPF_in) by the coefficient (k1). Details of this coefficient (k1) will be described later. Here, when the time derivative of the outlet temperature (TDPF_out) is large, it means that the rise of the outlet temperature is larger than the rise of the inlet temperature. Therefore, it can be determined that abnormal combustion of PM has occurred. Therefore, the process proceeds to step S9 to suppress the regeneration of the DPF 11.
[0023]
In step S7, it is determined whether or not the time differential value of the temperature difference (ΔT) between the outlet temperature (TDPF_out) of the DPF 11 and the inlet temperature (TDPF_in) of the DPF 11 is larger than the coefficient (k2). Details of this coefficient (k2) will be described later. Here, when the time differential value of the temperature difference (ΔT) is large, it means that the rise of the outlet temperature is larger than the rise of the inlet temperature, so that it can be determined that abnormal combustion of PM has occurred. Therefore, the process proceeds to step S9 to suppress the regeneration of the DPF 11.
[0024]
In step S8, it is determined whether or not the time differential value of the pressure difference (ΔP) between the inlet side and the outlet side of the DPF 11 is smaller than the coefficient (k3). Details of this coefficient (k3) will be described later. Here, since the time differential value of the pressure difference (ΔP) indicates the pressure change rate, it can be considered as an index of the combustion rate, that is, the relation of the combustion rate ∝−d (ΔP) / dt. Therefore, when the time differential value of the pressure difference (ΔP) is a very small value, it can be determined that the combustion speed is abnormally high, that is, PM abnormal combustion is occurring. Therefore, in such a case, the process proceeds to step S9 to suppress the regeneration of the DPF 11. If not, no abnormal combustion is recognized, so the routine proceeds to step S10, and normal DPF regeneration is continued.
[0025]
Note that the regeneration suppression mode of step S9 is a mode in which PM combustion is not stopped but is suppressed, and includes, for example, exhaust gas temperature reduction control (specifically, EGR cut, injection timing advance, etc.), exhaust The flow rate increase control (specifically, boost-up or the like) is performed to suppress the PM combustion and the DPF temperature.
[0026]
The above-described processing is repeatedly executed at regular small time intervals (for example, every 10 msec).
[0027]
The coefficients k1, k2, and k3 shown in the above flowchart are set as follows.
[0028]
FIG. 3 is a diagram showing a first threshold value k1 for suppressing the regeneration of the filter. The horizontal axis represents the engine speed (Ne), and the vertical axis represents the engine load.
[0029]
As can be seen from this diagram, k1 is set to be smaller as the rotation speed is higher and the load is lower, and to be larger as the rotation speed is lower and the load is higher. The reason will be described with reference to FIG.
[0030]
FIG. 4 is a diagram showing characteristics of the first threshold value k1. FIG. 4A shows a case of high rotation and low load, and FIG. 4B shows a case of low rotation and high load. The horizontal axis represents time, and the vertical axis represents temperature.
[0031]
In the case of high rotation and low load, the difference between the outlet temperature of the DPF 11 and the inlet temperature is small (FIG. 4A), and in the case of low rotation and high load, the difference between the outlet temperature of the DPF 11 and the inlet temperature is large. This can be seen (FIG. 4B).
[0032]
This is because the flow rate of the exhaust gas is high and the flow velocity is high in the case of high rotation and low load, so that the temperature difference between the inlet and the outlet is small. This is because the temperature difference between the inlet and the outlet increases.
[0033]
Therefore, as shown in FIG. 3, the reference value k1 for judging whether or not the combustion is abnormal is set to be smaller at a higher rotation and a lower load and larger at a lower rotation and a high load.
[0034]
FIG. 5 is a diagram showing a second threshold value k2 for suppressing the regeneration of the filter. The horizontal axis represents the engine speed (Ne), and the vertical axis represents the engine load.
[0035]
As can be seen from this diagram, k2 is set to be smaller as the rotation speed and the load are higher, and to be larger as the rotation speed and the load is lower. The reason will be described with reference to FIG.
[0036]
FIG. 6 is a diagram showing characteristics of the second threshold value k2. FIG. 6A shows a case of high rotation and low load, and FIG. 6B shows a case of low rotation and high load. The horizontal axis represents time, and the vertical axis represents temperature.
[0037]
In the case of high rotation and low load, the change in the temperature difference ΔT between the outlet temperature and the inlet temperature of the DPF 11 is small (FIG. 6A), and in the case of low rotation and high load, the temperature between the outlet temperature and the inlet temperature of the DPF 11 is small. It can be seen that the change in the difference ΔT is large (FIG. 6B).
[0038]
This is because the flow rate of the exhaust gas is high and the flow velocity is high in the case of high rotation and low load, so that the temperature difference between the inlet and the outlet is small.In the case of low rotation and high load, the flow rate of the exhaust gas is small and the flow velocity is slow. This is because the temperature difference between the inlet and the outlet increases.
[0039]
Therefore, as shown in FIG. 5, k2, which is a reference value for determining whether or not the combustion is abnormal, is set to be smaller at higher rotation speeds and lower loads, and to be larger at lower rotation speeds and high loads.
[0040]
FIG. 7 is a diagram showing a third threshold value k3 for suppressing the regeneration of the filter. The horizontal axis represents the engine speed (Ne), and the vertical axis represents the engine load.
[0041]
As can be seen from this diagram, k3 is set to be smaller for low rotation and low load, and to be large for high rotation and high load. The reason will be described with reference to FIG.
[0042]
FIG. 8 is a diagram showing the characteristics of the third threshold value k3. FIG. 8A shows the case of low rotation and low load, and FIG. 8B shows the case of high rotation and high load. The horizontal axis represents time, and the vertical axis represents temperature.
[0043]
In the case of low rotation and low load, the change in the pressure difference ΔP between the outlet pressure and the inlet pressure of the DPF 11 is small (FIG. 8A), and in the case of high rotation and high load, the pressure between the outlet pressure and the inlet pressure of the DPF 11 is small. It can be seen that the change in the difference ΔP is large (FIG. 8B).
[0044]
This is because the flow rate of the exhaust gas is small in the case of low rotation and low load, the pressure difference between the inlet and the outlet and the change width thereof are small, and in the case of high rotation and high load, the flow rate of the exhaust gas is large, This is because the pressure difference from the outlet and the change width thereof increase.
[0045]
Therefore, as shown in FIG. 7, k3, which is a reference value for determining whether or not the combustion is abnormal, is set smaller for lower rotation and lower load and larger for higher rotation and high load.
[0046]
Next, with reference to the drawings, effects in the case of suppressing DPF regeneration will be described.
[0047]
FIG. 9 is a diagram showing temperature changes at the inlet and outlet of the DPF. The horizontal axis represents time, and the vertical axis represents temperature.
[0048]
FIG. 10 is a diagram illustrating a change in the temperature difference between the inlet and the outlet of the DPF. The horizontal axis represents time, and the vertical axis represents the temperature difference ΔT between the DPF outlet and the inlet (= TDPF_out−TDPF_in).
[0049]
FIG. 11 is a diagram showing the time differentiation of the temperature difference. The horizontal axis represents time, and the vertical axis represents the time differential value (d (ΔT) / dt) of the temperature difference ΔT.
[0050]
Until time t0, the DPF outlet temperature is lower than the inlet temperature (FIG. 9), and the temperature difference ΔT is a negative value (FIG. 10). When the DPF outlet temperature and the inlet temperature exceed the PM ignition temperature (T1) at time t0 and the combustion of PM starts at time t1, the heat causes the DPF outlet temperature to rise rapidly (FIG. 9), and the value of the temperature difference ΔT also increases. It increases rapidly (FIG. 10). If no control is performed here, the DPF outlet temperature will greatly exceed the DPF allowable upper limit temperature (T0) (shown by a broken line in FIG. 9).
[0051]
Therefore, when the time differential value of the temperature difference ΔT exceeds k2 (step S7 in the flowchart, time t2 in FIG. 11), the DPF regeneration is suppressed (step S9 in the flowchart). Then, the time differential value of the temperature difference ΔT sharply drops (FIG. 11), excessive combustion of PM is suppressed, and the DPF outlet temperature drops and becomes the same level as the inlet temperature (FIG. 9), and the temperature difference ΔT decreases. Since it converges to zero, the DPF outlet temperature can be kept lower than the DPF allowable upper limit temperature (T0), and the DPF can be prevented from deteriorating.
[0052]
Next, a case where the regeneration of the DPF is suppressed when the time differential value of the pressure difference ΔP between the inlet and the outlet of the DPF falls below k3 will be described with reference to FIG.
[0053]
FIG. 12 is a diagram showing a change in the pressure difference between the inlet and the outlet of the DPF. The horizontal axis represents time, and the vertical axis represents the time differential value of ΔP (d (ΔP) / dt).
[0054]
At time t0, the DPF outlet temperature and the inlet temperature exceed the PM ignition temperature, and at time t1, PM combustion starts (FIG. 9).
[0055]
When the combustion of PM starts, the DPF is regenerated, so that the pressure difference ΔP sharply decreases, and the time derivative d (ΔP) / dt also decreases (time t1 to t2 in FIG. 12). However, if the PM combustion is excessive, the DPF deteriorates. Therefore, when the time differential value (d (ΔP) / dt) falls below k3 (step S8 in the flowchart, time t2 in FIG. 12), DPF regeneration is performed. Suppress (step S9 in the flowchart). Then, the time differential value of the pressure difference ΔP sharply rises (FIG. 12), abnormal combustion of PM is suppressed, and the time differential value converges to zero, so that deterioration of the DPF can be prevented.
[0056]
Also, even if the regeneration of the DPF is suppressed, if the outlet temperature of the DPF still exceeds the DPF allowable upper limit temperature (T0) (step S2 in the flowchart), the DPF regeneration is stopped to stop the PM combustion ( In step S3 of the flowchart, the PM combustion is stopped to prevent the DPF from deteriorating. Specifically, as described above, for example, λ control may be performed. The content of the λ control will be described with reference to FIG.
[0057]
FIG. 13 is a diagram illustrating λ control in the reproduction stop mode. The horizontal axis represents time, and the vertical axis represents λ (excess air ratio).
[0058]
In the present embodiment, at time t2, the target λ (dot-dash line) is reduced to perform intake throttle and EGR control. Then, the real λ falls as shown by the solid line. In this way, the amount of oxygen supplied to the DPF decreases, so that the PM does not burn and the DPF can be prevented from deteriorating.
[0059]
According to the present embodiment, since abnormal combustion of PM in the DPF is determined based on the temperatures at the inlet and the outlet of the DPF, even if abnormal combustion occurs in a part of the DPF, abnormal combustion is detected. And the DPF can be reliably protected.
[0060]
Further, since the abnormal combustion of PM in the DPF is determined based on the time differential value of the pressure difference between the inlet and the outlet of the DPF, that is, the combustion speed, even if abnormal combustion occurs in a part of the DPF, abnormal combustion occurs. Can be detected, and the DPF can be reliably protected.
[0061]
Furthermore, since the thresholds (k1, k2, k3) for judging each state are set according to the engine speed and the engine load, even if the driving condition changes, an accurate judgment can be made without erroneous judgment. It can be performed.
[0062]
Further, when the DPF outlet temperature exceeds the allowable upper limit temperature for maintaining the performance of the DPF during the regeneration of the DPF, the regeneration of the DPF is immediately stopped, so that the performance of the DPF does not deteriorate. Performance can be maintained.
[0063]
Without being limited to the embodiments described above, various modifications and changes are possible within the scope of the technical idea, and it is apparent that they are equivalent to the present invention.
[0064]
For example, in the above embodiment, the thresholds k1, k2, and k3 are defined based on the engine speed and the engine load, but may be defined based on the exhaust gas flow rate and the DPF inlet temperature. In this case, the thresholds k1, k2, and k3 may be as shown in FIG.
[0065]
FIG. 14A shows the first threshold value k1. As is clear from this figure, k1 is smaller at lower temperatures and higher speeds, and is larger at higher temperatures and low speeds. FIG. 14B shows the second threshold value k2. As is clear from this figure, k2 is smaller at high temperatures and low speeds, and is large at high temperatures and low speeds. FIG. 14C shows a third threshold value k3. As is apparent from this figure, k3 is smaller at low temperatures and low speeds, and is large at high temperatures and high speeds.
[0066]
This will be described with reference to FIGS. 3, 5, and 7, that is, the exhaust gas flow rate is proportional to the engine speed, and the DPF inlet temperature is proportional to the engine load. That is, FIG. 14A is in a proportional relationship with FIG. 3, FIG. 14B is in a proportional relationship with FIG. 5, and FIG. 14C is in a proportional relationship with FIG. Therefore, these may be appropriately selected by a method that is easy to control.
[0067]
In the above embodiment, for example, it is determined whether or not the outlet temperature (TDPF_out) of the DPF 11 exceeds the allowable upper limit temperature (T0) of the DPF 11 in step S2, and the time differential value of the outlet temperature (TDPF_out) of the DPF 11 in step S6 is determined. Is greater than the value obtained by multiplying the time derivative of the inlet temperature (TDPF_in) by the coefficient (k1), the temperature difference between the outlet temperature of the DPF 11 (TDPF_out) and the inlet temperature of the DPF 11 (TDPF_in) in step S7. It is determined whether the time differential value of (ΔT) is larger than the coefficient (k2), and the time differential value of the pressure difference (ΔP) between the inlet side and the outlet side of the DPF 11 in step S8 is calculated based on the coefficient (k3). Is determined once each, but may be performed a plurality of times or may be omitted as necessary. Accuracy can be improved by performing it a plurality of times, and control time can be shortened by omitting it. What is necessary is just to adjust suitably according to the characteristic of a system.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a filter regeneration control device for a diesel engine of the present invention.
FIG. 2 is a flowchart for explaining the operation of a filter regeneration control device for a diesel engine, focusing on the operation of an engine control unit.
FIG. 3 is a diagram showing a first threshold value k1 for suppressing the regeneration of a filter.
FIG. 4 is a diagram showing characteristics of a first threshold value k1.
FIG. 5 is a diagram showing a second threshold value k2 for suppressing regeneration of a filter.
FIG. 6 is a diagram illustrating characteristics of a second threshold value k2.
FIG. 7 is a diagram showing a third threshold value k3 for suppressing regeneration of a filter.
FIG. 8 is a diagram showing characteristics of a third threshold value k3.
FIG. 9 is a diagram showing temperature changes at the inlet and outlet of the DPF.
FIG. 10 is a diagram showing a change in a temperature difference between an inlet and an outlet of a DPF.
FIG. 11 is a diagram showing a time derivative of a temperature difference between an inlet and an outlet of the DPF.
FIG. 12 is a diagram showing a change in a pressure difference between an inlet and an outlet of a DPF.
FIG. 13 is a diagram illustrating λ control in a reproduction stop mode.
FIG. 14 is a diagram showing a first threshold value k1, a second threshold value k2, and a third threshold value k3 for suppressing filter regeneration.
[Explanation of symbols]
10 DPF regeneration control device 11 DPF (filter)
12 Differential pressure sensor (pressure difference measuring means)
13 DPF inlet temperature sensor (temperature measuring means)
14 DPF outlet temperature sensor (temperature measuring means)
15 A / F sensor 16 Engine control unit (reproduction restriction judging means, reproduction control means)
20 diesel engine

Claims (11)

A filter provided in an exhaust system of the diesel engine to collect particulates in the exhaust gas, and to burn and regenerate the collected particulates at a filter regeneration timing;
Temperature measuring means for measuring the temperature of the filter,
During the regeneration of the filter, regeneration restriction determining means for determining a restriction on filter regeneration based on the temperature measured by the temperature measuring means,
Regeneration control means for controlling filter regeneration based on the judgment of the regeneration restriction judgment means,
A filter regeneration control device for a diesel engine comprising: The temperature measuring means measures an outlet temperature of the filter,
The regeneration restriction determining means, during regeneration of the filter, when the outlet temperature exceeds the permissible temperature for maintaining the performance of the filter, determines the stop of the filter regeneration,
The regeneration control unit stops regeneration of the filter based on the determination of the regeneration restriction determination unit,
The diesel engine filter regeneration control device according to claim 1, wherein: The temperature measuring means measures an outlet temperature and an inlet temperature of the filter,
The regeneration restriction determining means determines suppression of filter regeneration based on the time differential value of the outlet temperature and the time differential value of the inlet temperature during filter regeneration,
The regeneration control unit suppresses regeneration of the filter based on the determination by the regeneration restriction determination unit.
The diesel engine filter regeneration control device according to claim 1, wherein: The regeneration restriction judging means judges suppression of filter regeneration when the time derivative of the outlet temperature exceeds a value obtained by multiplying the time derivative of the inlet temperature by a first predetermined value during regeneration of the filter. Do
The diesel engine filter regeneration control device according to claim 3, wherein: The first predetermined value is smaller as the engine is higher in speed and lower in load, and is larger as the engine is lower in speed and higher in load.
The diesel engine filter regeneration control device according to claim 4, wherein: The temperature measuring means measures an outlet temperature and an inlet temperature of the filter,
The regeneration restriction determining unit determines suppression of filter regeneration based on a time differential value of a difference between the outlet temperature and the inlet temperature during filter regeneration,
The regeneration control unit suppresses regeneration of the filter based on the determination by the regeneration restriction determination unit.
The diesel engine filter regeneration control device according to claim 1, wherein: The regeneration restriction determining means determines, during regeneration of the filter, suppression of filter regeneration when a time derivative of a difference between the outlet temperature and the inlet temperature exceeds a second predetermined value.
The diesel engine filter regeneration control device according to claim 6, wherein: The second predetermined value is smaller as the engine speed is higher and the load is lower, and is larger as the engine speed is lower and the load is higher.
The filter regeneration control device for a diesel engine according to claim 7, wherein: A filter provided in the exhaust system of the diesel engine, for collecting particulates in the exhaust gas, and burning and regenerating the collected particulates when it is time to regenerate the filter;
Pressure difference measuring means for measuring the pressure difference between the outlet and the inlet of the filter,
Regeneration restriction determining means for determining suppression of filter regeneration based on a time differential value of the pressure difference during regeneration of the filter,
A regeneration control unit that suppresses regeneration of the filter based on the determination by the regeneration restriction determination unit;
A filter regeneration control device for a diesel engine comprising: The regeneration restriction determining means determines the suppression of filter regeneration when the time differential value of the pressure difference falls below a third predetermined value during filter regeneration.
The diesel engine filter regeneration control device according to claim 9, wherein: The third predetermined value is smaller as the engine speed is lower and the load is lower, and is larger as the engine speed is higher and the load is higher.
The diesel engine filter regeneration control device according to claim 10, wherein:

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