JP2004132358A - Filter control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To regenerate at a proper timing a filter for trapping particulates contained in exhaust gas from an engine. <P>SOLUTION: This filter control device comprises a first estimation computing part 100 for outputting first estimated data XA computed by filter front-rear differential pressure to operate the estimation of a particulate accumulated amount of the filter 32 and a second estimation computing part 110 for outputting second estimated data XB in accordance with an engine operated condition. Higher reliable one of the first and second estimated data XA, XB in the point of view of an engine speed is selected to determine whether the filter should be regenerated or not. In consideration of a difference between the first and second estimated data XA, XB, when the difference is greater than a preset value even if the engine speed is higher, the selection of the first estimated data XA is avoided in which the accumulated particulates may have a lower reliable estimated value due to cracking. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a filter control device capable of reproducing a filter for collecting particulates contained in exhaust gas of an engine at an appropriate timing.
[0002]
[Prior art]
In recent years, various devices have been installed in the exhaust system of diesel engines to post-treat diesel particulates in exhaust gas in order to suppress the diffusion of fine particles contained in the exhaust gas of diesel engines into the atmosphere. Are being developed. Each of these types of exhaust gas treatment devices includes a filter for collecting particulates contained in exhaust gas discharged from a diesel engine when the exhaust gas passes through an exhaust passage. Therefore, the collected particulates are gradually deposited on the filter, and eventually the filter is clogged, which makes it difficult to pass the exhaust gas.
[0003]
Therefore, conventionally, when it is estimated that the amount of accumulated particulates in the filter has reached a predetermined level, the temperature of the filter is raised by heating the filter, etc., and the filter is incinerated by burning the particulates. It regenerates so that particulates can be collected again. As described above, the regeneration of the filter is performed by burning the particulates by heating the filter. Therefore, it is desired that the regeneration of the filter be performed at an appropriate timing.
[0004]
Therefore, conventionally, the pressure difference between the exhaust gas before and after the filter, that is, the pressure difference between the exhaust gas pressure on the inlet side of the filter and the exhaust gas pressure on the outlet side of the filter, is measured to measure the pressure difference. A configuration in which the amount of particulates is estimated, the filter regeneration timing is determined according to the estimation result, and filter regeneration control is performed is widely used.
[0005]
[Problems to be solved by the invention]
However, the above-described prior art has the following problems. When the engine speed is low, for example, because the engine enters an idle operation state, the flow rate of exhaust gas in the exhaust passage decreases, so the pressure difference before and after the filter is small even when the amount of accumulated particulates is small. As a result, it becomes difficult to accurately estimate the amount of accumulated particulates based on the differential pressure across the filter. In addition, when the exhaust gas is in a low pressure state, the input / output characteristics of the pressure sensor indicating the relationship between the exhaust gas pressure and the output signal of the pressure sensor do not become linear characteristics. For this reason, the accuracy of the pressure information of the output signal of the pressure sensor becomes low, and the level of the output signal from the pressure sensor also becomes low, so that the output signal is easily affected by noise. It is difficult to accurately estimate the amount of sedimentation.
[0006]
Further, if the high temperature condition of the filter continues while the operation of the engine is stopped after the particulates are deposited on the filter, volatile components in the particulates deposited in the filter are released, and the particulates are released. The curate cracks. When such cracks occur, the exhaust gas passes through the cracks and passes through the inside of the filter, so that the ventilation resistance of the filter decreases. As a result, the pressure difference between before and after the filter becomes smaller than before the cracks are generated, and in such a state, when the amount of accumulated particulates is estimated by the differential pressure of the exhaust gas, the amount of accumulated particulates is as if The result of estimation is that the number of particulates has decreased, making it difficult to accurately estimate the amount of accumulated particulates.
[0007]
For this reason, in a conventional apparatus that controls the regeneration of the filter by measuring the differential pressure of the exhaust gas before and after the filter, the regeneration is executed in a state where the amount of the particulates deposited on the filter is large, and There is a risk of causing erosion. In addition, since it is difficult to accurately estimate the amount of accumulated particulates, the frequency of regeneration of the filter increases, which causes a problem that fuel efficiency is reduced and the life of the filter is shortened.
[0008]
An object of the present invention is to provide a filter control device capable of solving the above-mentioned problems in the conventional technology.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the present invention, the amount of accumulated particulates in a filter for collecting particulates contained in exhaust gas of an engine is estimated, and the filter is regenerated based on the estimation result. In the filter control device, the amount of accumulated particulates is estimated based on the pressure difference between the exhaust gas before and after the filter, and the amount of accumulated particulates is estimated based on the operating state of the engine. Any one of them is selectively taken out according to the operation state of the engine and the comparison result of the two estimated values, and it is determined whether or not to regenerate the filter based on the taken out estimation result. is there.
[0010]
According to the first aspect of the invention, there is provided a filter control for estimating a particulate accumulation amount in a filter for collecting particulates contained in exhaust gas of an engine, and regenerating the filter based on the estimation result. A detecting means for detecting an operation state of the engine; a first estimating means for estimating a particulate accumulation amount of the filter based on a pressure difference between exhaust gas before and after the filter; A second estimating unit for estimating a particulate accumulation amount of the filter based on a state; and a difference computing unit for computing a difference between the particulate accumulation amount estimation values obtained by the first and second estimating units. Selecting one of the estimation results of the first and second estimation means in response to the difference calculation means and the detection means , Filter control apparatus adapted to determine the playback timing of the filter is proposed according to the estimated result selected.
[0011]
According to a second aspect of the present invention, in the first aspect of the invention, the second estimating means includes a fuel injection amount to the engine, a rotation speed of the engine, an exhaust gas recirculation rate in the engine, and a pre-filter temperature. There is proposed a filter control device in which an operation for estimating the amount of accumulated particulates is performed based on at least one of the following.
[0012]
According to a third aspect of the present invention, in the first aspect of the invention, the second estimating means uses actual measurement data obtained by measuring an increase in the amount of particulate accumulation per unit time using an actual engine. There has been proposed a filter control device that performs a calculation for estimating the amount of accumulated particulates using a calculated map calculation.
[0013]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the second estimating means obtains an estimated value of the amount of accumulated particulates in the filter by integrating the data obtained by the map operation. A configured filter control device is proposed.
[0014]
According to the invention of claim 5, in the invention of claim 4, every time the engine is stopped, the estimated value of the particulate accumulation amount used for the filter regeneration control at that time is stored, and the stored value is stored. There is proposed a filter control device in which the value of the particulate accumulation value is used as an initial value for integration in the second estimating means.
[0015]
According to the invention of claim 6, in the invention of claim 1, when selecting one of the estimation results of the first and second estimation means, a shift amount between the two estimation results is calculated, and the shift amount is calculated. Is stored as a learning value, and a filter control device is proposed in which the operation value in the second estimating means is corrected according to the learning value.
[0016]
According to a seventh aspect of the present invention, there is provided a filter control device according to the sixth aspect, wherein a coefficient according to the shift amount is calculated, and the calculated value in the second estimating means is corrected by the coefficient. You.
[0017]
According to an eighth aspect of the present invention, there is provided a filter control device according to the sixth aspect, wherein when the deviation exceeds a predetermined value, the fact is displayed to an operator.
[0018]
According to a ninth aspect of the present invention, in the first aspect of the invention, when the difference is equal to or more than a predetermined value at the time of starting the engine, the estimation result of the second estimating means is determined regardless of the detection result of the detecting means. A filter control device adapted to be selected is proposed.
[0019]
According to a tenth aspect of the present invention, in the first aspect of the invention, when the difference is equal to or more than a predetermined value at the time of starting the engine, the second estimating means is provided for a predetermined period regardless of the detection result of the detecting means. There is proposed a filter control device that selects the estimation result of.
[0020]
According to an eleventh aspect of the present invention, in the invention of the tenth aspect, the predetermined period is a period until the particulate matter accumulation amount estimation value started from the start of the engine by the second estimation means reaches a predetermined value. Is proposed.
[0021]
According to the twelfth aspect, in the ninth aspect, when the difference is smaller than the predetermined value, the estimation result by the first estimating means is selected instead of the estimation result by the second estimating means. There is proposed a filter control device adapted to do so.
[0022]
According to the above configuration, either one of the particulate matter accumulation amount estimated value obtained based on the exhaust gas pressure difference before and after the filter, or the particulate matter accumulation amount estimated value calculated from the operating parameters of the engine, etc. Is selectively used in consideration of the operating state of the vehicle and the difference between the two estimated values. As a result, it is possible to more accurately estimate the amount of accumulated particulates, and it is possible to more appropriately determine an appropriate timing of filter regeneration.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0024]
FIG. 1 is an overall configuration diagram illustrating an example of an embodiment in which the present invention is applied to control of a filter for exhaust gas aftertreatment of a diesel engine. Reference numeral 1 denotes a four-cylinder diesel engine, and injectors 6 to 9 are provided in each of the cylinders 2 to 5. The operation of the injectors 6 to 9 is controlled by the engine control unit 10 and has a known configuration in which high-pressure fuel can be injected and supplied into a corresponding cylinder at a required timing by a required amount.
[0025]
The intake duct 12 connected to the intake manifold 11 is provided with an intercooler 13 and an air cleaner 14, while the exhaust duct 16 connected to the exhaust manifold 15 is provided with an exhaust gas aftertreatment device 30. ing.
[0026]
An exhaust recirculation path 18 provided with an EGR control valve 17 is provided between the intake duct 12 and the exhaust duct 16, and the opening degree of the EGR control valve 17 is controlled by an actuator 19 controlled by the engine control unit 10. A part of the adjusted exhaust gas flowing through the exhaust duct 16 can be metered and returned to the intake manifold 11. Reference numeral 20 denotes an exhaust turbocharger, which includes an exhaust turbine 21 disposed in the exhaust duct 16 and a compressor 22 disposed in the intake duct 12 and driven by the exhaust turbine 21. .
[0027]
The exhaust gas post-processing device 30 includes an oxidation catalyst 31 and a filter 32 for collecting particulates. The exhaust gas flowing in the exhaust duct 16 passes through the oxidation catalyst 31 and then passes through the filter 32. . The oxidation catalyst 31 forms a wash coat layer by coating activated alumina or the like on the surface of a carrier made of, for example, honeycomb cordierite or heat-resistant steel, and forms a noble metal such as platinum, palladium, or rhodium on the coat layer. It is configured to carry a catalytically active component consisting of The oxidation catalyst oxidizes NO in the exhaust gas to NO. ₂ And oxidize HC and CO in the exhaust gas to produce H ₂ O and CO ₂ Is generated.
[0028]
The filter 32 includes, for example, a so-called wall flow type honeycomb filter in which a large number of cells are formed in parallel with, for example, porous cordierite or silicon carbide, and an inlet and an outlet of the cells are alternately closed. It uses a fiber filter wrapped around a stainless steel perforated tube in multiple layers to collect particulates in exhaust gas.
[0029]
A first pressure sensor 33 and a second pressure sensor 34 for detecting the pressure of the exhaust gas are provided on the inlet side (front) and the outlet side (rear) of the filter 32, respectively. The first pressure sensor 33 outputs a first pressure signal SA indicating the exhaust gas pressure P1 on the inlet side of the filter 32, and the second pressure sensor 34 outputs a second pressure indicating the exhaust gas pressure P2 on the outlet side of the filter 32. Signal SB is output. Reference numeral 35 denotes a flow rate sensor for detecting the flow rate of the exhaust gas flowing in the exhaust duct 16, and an exhaust flow rate signal F from the flow rate sensor 35 includes a first pressure signal SA and a second pressure signal SB. Are input to the filter control unit 40.
[0030]
Here, instead of the flow rate detection by the flow rate sensor 35, the flow rate of the exhaust gas may be obtained by calculation from the intake air amount, the injection amount, the exhaust temperature, and the exhaust pressure. In this case,
PV = nRT
(Where, P; pressure, V; volume, T; temperature, nR; gas constant)
The volume flow rate can be calculated by calculating the time derivative of the volume using the relational expression.
[0031]
The filter control unit 40 is a device that estimates the amount of accumulated particulates collected by the filter 32 and performs engine control for regenerating the filter 32 based on the estimation result.
[0032]
FIG. 2 is a block diagram showing a schematic configuration of the filter control unit 40. The filter control unit 40 performs an estimation calculation of the amount of particulates deposited on the filter 32 and outputs estimation value data X indicating the estimation result, and controls the regeneration of the filter 32 based on the estimation value data X. And a reproduction control unit 42 for performing the reproduction. The estimation operation unit 41 receives a first pressure signal SA, a second pressure signal SB, an exhaust flow rate signal F, and engine operation data M indicating operation conditions of the diesel engine 1. Here, as the engine operation data M, a fuel injection amount signal Q indicating an operation state of the diesel engine 1, an engine speed signal N, and a circulation rate signal R indicating an exhaust gas circulation (EGR) rate are input from the engine control unit 10. However, at least one of these signals can be used as the engine operation data M. The filter control unit 40 also receives a temperature signal T0 indicating the pre-entrance temperature of the filter 32 sent from the temperature sensor 36 provided on the inlet side of the filter 32.
[0033]
The reproduction control unit 42 responds to the estimation data X and determines whether or not the amount of accumulated particulate exceeds a predetermined value. When it is determined from the estimated data X that the amount of particulates exceeds a predetermined value, a reproduction signal CS is output from the reproduction control unit 42, and the reproduction signal CS is input to the engine control unit 10. In response to the regeneration signal CS, the engine control unit 10 executes the retard control of the injection timing necessary for regeneration of the filter 32, thereby increasing the temperature of the exhaust gas, and The curate is burned to regenerate the filter 32.
[0034]
FIG. 3 is a detailed block diagram of the estimation operation unit 41. The estimation operation unit 41 estimates a particulate accumulation amount of the filter 32 based on an operation state of the diesel engine 1 and a first estimation operation unit 100 that estimates a particulate accumulation amount of the filter 32 from a differential pressure across the filter 32. A second estimation operation unit 110 is provided, and one of the operation outputs of the first estimation operation unit 100 and the second estimation operation unit 110 is selected as the estimated value data X by the selection unit 120 and output. .
[0035]
The first estimation calculation unit 100 determines the differential pressure of the exhaust gas pressure between the inlet side and the outlet side of the filter 32 that is collecting particulates in response to the first and second pressure signals SA and SB. A differential pressure calculating unit 101 for calculating a differential pressure (before and after the filter) ΔP, and a flow calculating unit 102 for calculating the flow rate FL of the exhaust gas flowing through the filter 32 based on the exhaust flow rate signal F from the flow rate sensor 35. ing. The output of the differential pressure calculation unit 101 and the output of the flow rate calculation unit 102 are input to the division unit 103, and the division unit 103 performs an operation for obtaining the value of ΔP / FL. Note that the flow rate calculation unit 102 may be configured to calculate the flow rate FL using the operation parameters of the diesel engine 1 as described above.
[0036]
The calculation result in the division unit 103 is input to the first accumulation amount calculation unit 105 via the digital filter 104, and the first accumulation amount calculation unit 105 estimates the particulate accumulation amount at that time based on the value of ΔP / FL. The value is calculated. The estimation calculation result obtained by the first accumulation amount calculation unit 105 is output as first estimation data XA.
[0037]
An example of the configuration of the first estimation calculation unit 100 has been described above. However, a technique for calculating and estimating the amount of particulate accumulated in the filter based on the pressure difference before and after the filter is itself known, and therefore, FIG. The configuration of the first estimation calculation unit 100 shown in FIG. 3 can be replaced with another known configuration.
[0038]
Next, the second estimation calculation unit 110 will be described. The second estimation calculation unit 110 is configured as means for performing estimation calculation of the amount of accumulated particulates in the filter 32 based on the operation state of the diesel engine 1. The second estimation calculation unit 110 includes a second accumulation amount calculation unit 111 for calculating the estimated value of the particulate accumulation amount per unit time in the filter 32 based on the operation condition data. In the present embodiment, the second accumulation amount calculation unit 111 calculates the estimated accumulation amount ΔY of particulates per unit time at that time based on the fuel injection amount signal Q, the engine speed signal N, and the circulation rate signal R. The calculation is performed.
[0039]
When the temperature of the filter 32 rises as the temperature of the exhaust gas rises, the particulates deposited there burn and the deposited particulates decrease. That is, the regeneration operation of the filter 32 is performed. Reference numeral 112 denotes a regeneration amount calculation unit for estimating the reduction amount of the accumulated particulates due to such combustion as the regeneration amount from the operation state of the diesel engine 1. The regeneration amount calculation unit 112 responds to the fuel injection amount signal Q, the engine speed signal N, the circulation rate signal R, the temperature signal T0, and the second estimation data XB obtained as described later, and The combustion amount per unit time of the curate is estimated and calculated as the regeneration amount estimation value ΔZ.
[0040]
The estimated accumulation amount ΔY per unit time from the second accumulation amount calculation unit 111 and the estimated regeneration amount per unit time ΔZ from the reproduction amount calculation unit 112 are stored in the integration operation unit 113 as the accumulation data DY and the reproduction data DZ, respectively. Sent. The initial value data ID indicating the initial value of the integration is input from the selection unit 120 to the integration operation unit 113. As the initial value data ID, the value of the estimated value data X stored in the selection unit 120 at the time of the most recent engine stop as described later is used. Using the initial value data ID, the integration operation unit 113 performs time integration processing on the deposition data DY and the reproduction data DZ with the polarities shown. The integration calculation result obtained by the integration calculation unit 113 is the estimation calculation result by the second estimation calculation unit 110. That is, second integration data XB indicating an estimated value obtained by calculating the amount of accumulated particulates in filter 32 from the operation state of diesel engine 1 is output from integration operation section 113.
[0041]
The second estimation data XB is also input to the regeneration amount calculation unit 112 as described above, and the regeneration amount calculation unit 112 outputs the fuel injection amount signal Q, the engine speed signal N, the circulation rate signal R, the temperature signal T0, and the (2) The reproduction amount estimation value ΔZ per unit time is calculated based on the estimation data XB. The reason why the second estimation data XB is considered in the estimation calculation in the regeneration amount calculation unit 112 is that even if the conditions such as the exhaust gas temperature are the same, the regeneration amount is affected by the amount of accumulated particulates at that time. This is because a more accurate reproduction amount estimation is performed in consideration of this influence.
[0042]
In addition, each calculation in the first accumulation amount calculation unit 105, the second accumulation amount calculation unit 111, and the regeneration amount calculation unit 112 can be a map calculation. In this case, each map data used is an actual engine with a filter. , The test bench is set to predetermined input conditions in advance, the deposition amount or the regeneration amount is measured, and it can be appropriately determined based on the measurement result.
[0043]
The selection unit 120 selects one of the first estimation data XA and the second estimation data XB in consideration of the operation state of the diesel engine 1 and a difference between the first estimation data XA and the second estimation data XB, The selected estimated data is output as estimated value data X indicating the estimated value of the accumulated particulate amount in the filter 32 at that time.
[0044]
In the present embodiment, an engine speed signal N is input to selection section 120 as a signal indicating the operating state of diesel engine 1.
[0045]
FIG. 4 is a flowchart illustrating the configuration and operation of the selection unit 120. Hereinafter, the selection unit 120 will be described with reference to FIG. First, in step S1, it is determined based on the engine speed signal N whether or not the engine speed EN is greater than a predetermined value Ne. The predetermined value Ne indicates a lower limit value of the engine speed at which the particulate accumulation amount at that time can be correctly estimated based on the differential pressure across the filter 32. The predetermined value Ne can be, for example, an idle speed.
[0046]
If the engine speed EN is equal to or less than the predetermined value Ne, the determination result of step S1 is NO, and the process proceeds to step S2, where the second estimated data XB is selected as the estimated value data X. On the other hand, if the engine speed is greater than the predetermined value Ne, the result of the determination in step S1 is YES and the process proceeds to step S3.
[0047]
In step S3, the first estimation data XA and the second estimation data XB are compared, and it is determined whether or not the absolute value ΔM of the difference is larger than a predetermined value K. If ΔM> K, cracks have occurred in the particulates accumulated in the filter, and it is considered that ΔM has increased, and the reliability of the value of the first estimation data XA is determined to be low. Is done. Therefore, if the decision result in the step S3 is YES, the process proceeds to a step S2, where the second estimated data XB is selected, and the second estimated data XB is output as the estimated value data X. On the other hand, if ΔM ≦ K, the decision result in the step S3 is NO, and the process proceeds to a step S4.
[0048]
In step S4, it is further determined whether or not the amount of accumulated particulates since the start of the diesel engine 1 this time has reached a predetermined amount sufficient to repair cracks. Here, a configuration in which the value of the second estimated data XB at the time of the latest engine stop and the current value of the second estimated data XB are compared to determine whether or not the current deposition amount is equal to or more than a predetermined amount is determined. It has become.
[0049]
Even if the result of the determination in step S3 is NO, if the current deposition amount is not equal to or more than the predetermined amount, the result of the determination in step S4 is NO, the process proceeds to step S2, and the second estimated data XB Selected. On the other hand, if the current deposition amount is equal to or more than the predetermined amount, the determination result of step S4 is YES, and the process proceeds to step S5, where the first estimation data XA is selected.
[0050]
As described above, when the engine speed EN is smaller than the predetermined value Ne, the second estimation data XB that is more reliable than the first estimation data XA is selected.
[0051]
When the absolute value ΔM of the difference between the first estimation data XA and the second estimation data XB is larger than K, it is considered that the cracks of the particulates accumulated in the filter are the main cause. , The second estimated data XB is selected as being more reliable.
[0052]
Even if ΔM ≦ K in step S3, as long as the current deposition amount does not exceed the predetermined value, the process proceeds to step S2, and the second estimation data XB is selected.
[0053]
When the time has elapsed from the start of the engine, the amount of accumulated particulates increases, and the determination result in step S4 becomes YES, the first estimation data XA is selected for the first time.
[0054]
After either the first estimated data XA or the second estimated data XB is selected in this way, the process proceeds to step S6, where it is determined whether or not the engine is stopped. If the diesel engine 1 has not stopped yet, the determination result in the step S6 is NO, the process returns to the step S1, and the above operation is repeatedly executed.
[0055]
If the operation of the diesel engine 1 is stopped by turning off the ignition key or the like, the determination result in step S6 is YES, and in step S7, the value of the estimated value data X at this time is stored in a memory (not shown) as the initial value data ID. The operation is terminated.
[0056]
By the way, in the case of the estimation calculation in the second estimation calculation unit 110, since the integration calculation is performed, it is expected that errors will be accumulated in the long term and the calculation result will be inaccurate. For this reason, in the embodiment shown in FIG. 3, the correction amount storage unit 114 and the correction value calculation unit 115 are provided in the second estimation calculation unit 110, and the per unit time calculated by the second accumulation amount calculation unit 111 is used. The amount of accumulated particulates is appropriately corrected by a learning operation.
[0057]
That is, the first estimation data XA and the second estimation data XB are input to the correction value calculation unit 115, and when the selection unit 120 selects the second estimation data XB, the rotation speed of the diesel engine 1 is reduced. When the selecting unit 120 performs a data switching operation so as to select the first estimation data XA instead of the second estimation data XB, the first estimation data XA at this time is returned in response to the switching operation. The difference from the second estimation data XB is calculated as follows.
[0058]
When the reproduction processing is not performed and the reproduction processing integrated value is zero, and the difference is within a predetermined range, the estimated value DXA based on the first estimated data XA and the estimated value DXB based on the second estimated data XB are determined. The ratio DXA / DXB is calculated as the shift coefficient C, and the shift coefficient C is stored in the correction amount storage unit 114.
[0059]
On the other hand, when the reproduction processing is performed and the reproduction processing integrated value is larger than zero, the first estimation data XA is subtracted from the second estimation data XB, and the reproduction processing integration value is divided by the subtraction result. The result is referred to as a shift coefficient C, and the shift coefficient C is stored in the correction amount storage unit 114.
[0060]
In any case, if the difference exceeds the predetermined range, it is determined that the filter has deteriorated, and the above-described calculation of the shift coefficient C is not performed. When the deterioration of the filter is determined in this way, it is preferable to provide a warning display by means such as turning on or blinking a predetermined lamp to prompt the driver to replace the filter.
[0061]
The shift coefficient C is stored as a learning value in the correction amount storage unit 114, and the shift coefficient C as the learning value is sent to the second accumulation amount calculation unit 111, where the accumulation of particulates per unit time calculated here is performed. The amount is then multiplied by the shift coefficient C and corrected. Thereafter, the corrected amount of accumulated particulate per unit time is output as the estimated amount of accumulated particulate per unit time ΔY.
[0062]
As described above, the correction coefficient calculation unit 115 calculates the shift coefficient C using the values of the first estimated data XA and the second estimated data XB, and the shift coefficient C is stored and accumulated in the correction amount storage unit 114. Correction at the time of performing the calculation processing for calculating the amount of accumulated particulates per unit time will be appropriately performed, and errors will not be accumulated in the integration calculation in the integration calculation unit 113 but will be corrected. As a result, the second estimation data XB, which is estimation data based on the amount of accumulated particulates per unit time, has a reliable value, so that the estimation of the amount of accumulated particulates is accurate.
[0063]
Since the filter control unit 40 is configured as described above, the estimated value of the particulate accumulation amount calculated based on the pressure difference before and after the filter, and the particulate accumulation simulated based on the operation state of the diesel engine 1 Among the two estimated values, the estimated value of the quantity and the estimated value having higher reliability are selected according to the state at that time. Then, whether or not to regenerate the filter 32 is determined according to the estimated value thus selected, so that the regeneration of the filter 32 can be executed at an extremely appropriate timing. As a result, it is possible to extend the life of the filter 32 as compared with the related art, and it is possible to expect a reduction in running cost.
[0064]
【The invention's effect】
According to the present invention, as described above, the estimated value of the particulate accumulation amount calculated based on the pressure difference before and after the filter, and the simulated particulate accumulation amount based on the particulate accumulation amount per unit time. Among the two estimated values, the estimated value having a higher reliability is selected according to the operating state of the engine at that time, and it is determined whether or not to regenerate the filter according to the estimated value thus selected. Since the determination is made, the regeneration of the filter can be executed at an extremely appropriate timing. As a result, the frequency of regeneration of the filter is optimized, the life of the filter can be made longer than in the past, and a reduction in running cost can be expected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of an embodiment of an exhaust gas treatment device provided with a filter control device according to the present invention.
FIG. 2 is a block diagram showing a configuration of a control unit in FIG. 1;
FIG. 3 is a block diagram illustrating a detailed configuration of an estimation calculation unit in FIG. 2;
FIG. 4 is a flowchart for explaining a selection unit in FIG. 3;
[Explanation of symbols]
1 Diesel engine
2-5 cylinders
6-9 Injector
10 Engine control unit
15 Exhaust manifold
16 Exhaust duct
40 Filter control unit
30 Exhaust gas aftertreatment device
31 oxidation catalyst
32 filters
33 1st pressure sensor
34 Second pressure sensor
35 Flow sensor
36 Temperature sensor
100 first estimator
101 Differential pressure calculator
102 Flow rate calculator
103 Division
105 First accumulation amount calculation unit
110 second estimation operation unit
111 second accumulation amount calculation unit
112 Playback amount calculation unit
113 Integral operation unit
114 Correction amount storage unit
115 Correction value calculator
120 Selector
N engine speed signal
P1, P2 Exhaust gas pressure
Q Fuel injection amount signal
R circulation rate signal
SA 1st pressure signal
SB 2nd pressure signal
T0 temperature signal
X estimated value data
XA first estimation data
XB Second estimated data
ΔP Differential pressure
ΔY Deposit amount estimate
ΔZ Reproduction amount estimate

Claims (12)

In a filter control device that estimates a particulate accumulation amount in a filter for collecting particulates contained in exhaust gas of an engine and regenerates the filter based on the estimation result,
Detecting means for detecting an operating state of the engine;
First estimating means for estimating a particulate accumulation amount of the filter based on a pressure difference of exhaust gas before and after the filter,
Second estimating means for estimating a particulate accumulation amount of the filter based on an operation state of the engine;
And a difference calculating means for calculating a difference between the particulate matter accumulation amount estimated values obtained by the first and second estimating means,
A filter control device which responds to the difference calculation means and the detection means, selects one of the estimation results of the first and second estimation means, and determines the regeneration timing of the filter according to the selected estimation result. The second estimating means for estimating a particulate accumulation amount based on at least one of a fuel injection amount to the engine, a rotation speed of the engine, an exhaust gas recirculation rate in the engine, and a pre-filter temperature. The filter control device according to claim 1, wherein the calculation is performed. In the second estimating means, an estimation calculation of the particulate accumulation amount is performed by using a map operation using actual measurement data obtained by measuring an increase in the particulate accumulation amount per unit time using an actual engine. 2. The filter control device according to claim 1, wherein: 4. The filter control device according to claim 3, wherein the second estimating unit is configured to obtain an estimated value of a particulate accumulation amount in the filter by integrating data obtained by the map calculation. 5. Each time the engine is stopped, the estimated value of the particulate accumulation amount used for the filter regeneration control at that time is stored, and the stored value of the particulate accumulation value is calculated by the integration of the second estimation means. 5. The filter control device according to claim 4, wherein the filter control device is used as an initial value for the filter. When selecting one of the estimation results of the first and second estimation means, a shift amount between the two estimation results is calculated, and the shift amount is stored as a learning value, and the second difference is stored in accordance with the learning value. 2. The filter control device according to claim 1, wherein a calculation value in said estimating means is corrected. 7. The filter control device according to claim 6, wherein a coefficient according to the shift amount is calculated, and the calculated value in the second estimating means is corrected by the coefficient. 7. The filter control device according to claim 6, wherein when the shift amount exceeds a predetermined value, the fact is displayed to an operator. 2. The filter control device according to claim 1, wherein when the difference is equal to or greater than a predetermined value when the engine is started, the estimation result of the second estimation unit is selected regardless of the detection result of the detection unit. 2. The filter control according to claim 1, wherein when the difference is equal to or greater than a predetermined value when the engine is started, the estimation result of the second estimation means is selected during a predetermined period regardless of the detection result of the detection means. apparatus. The filter control device according to claim 10, wherein the predetermined period is a period until the estimated particulate accumulation amount started from the start of the engine by the second estimation unit reaches a predetermined value. 10. The filter control device according to claim 9, wherein when the difference is smaller than the predetermined value, the estimation result by the first estimation unit is selected instead of the estimation result by the second estimation unit.

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