JP2021050702A - Method and device for controlling vehicle including exhaust emission control system - Google Patents

Abstract

To suppress emission of N2O on a vehicle including an exhaust emission control system.SOLUTION: A device for controlling a vehicle including an exhaust emission control system includes: an estimation unit 112a for estimating an amount of CO2 and N2O contained in an exhaust gas from an internal combustion engine; a ratio calculation unit 113 for calculating a ratio of N2O to CO2 using the CO2 and N2O estimated by the estimation unit 112a; and an N2O suppression unit 114 for performing N2O suppression control on the basis of the ratio calculated by the ratio calculation unit 113.SELECTED DRAWING: Figure 6

Description

The present invention relates to a control method and a control device for a vehicle provided with an exhaust gas purification device.

As an exhaust gas purification device for an internal combustion engine, a NOx storage reduction catalyst (Lean NOx Trap: hereinafter referred to as "LNT"), a urea SCR (Selective Catalytic Reduction), and a combination thereof are known (see, for example, Patent Document 1). ).

LNT oxidizes NO in the exhaust gas to NO ₂ , and temporarily occludes and adsorbs this in Ba, Ce, etc. in the catalyst. In LNT, when _{the occluded amount of NO 2} reaches a predetermined amount, the exhaust gas air-fuel ratio is controlled to be in a rich state while considering the temperature and stable conditions. In a rich state, NO ₂ occluded in the catalyst is reduced by HC and CO in the exhaust gas, and is discharged as harmless gas such as _{CO 2} , H ₂ O, and N _2. In LNT, such an operation is repeated.

The urea SCR injects urea water into the exhaust pipe in front of the SCR catalyst, and reduces NOx to nitrogen (N _{2 ) by ammonia (NH 3) in the SCR catalyst.}

Japanese Unexamined Patent Publication No. 2014-066232

_{By the way, harmful gas components such as ammonia NH 3} and nitrous oxide N ₂ O may be generated at the time of rich reduction, although they are minute. NH ₃ is produced by reacting with hydrogen when _{the O 2} concentration in the exhaust gas is insufficient in a state of excessive richness. On the other hand, N ₂ O may be produced in the reduction process. It is known that N ₂ O has an effect equivalent to 300 times that _{of CO 2} as a warming substance, _{and it is being considered in Europe to convert N 2} O into CO ₂ and make it subject to regulation. Therefore, to estimate the emissions N 2 _O, is possible to suppress the emission has become important.

An object of the present invention, in a vehicle having an exhaust gas purifying device is to provide a control method and a control device can suppress the emission of N 2 _O.

One aspect of the vehicle control method provided with the exhaust gas purification device of the present invention is.
An estimation step for estimating the amount of _{CO 2} and N ₂ O contained in the exhaust gas of an internal combustion engine, and
Using the CO ₂ estimated value estimated by the estimation step and N _{2 O} estimates, the ratio calculation step of calculating the ratio of N _{2 O} estimates for CO ₂ estimates,
Based on the ratio calculated by said ratio calculating step, and N _{2 O} suppression step of suppressing control of N 2 _O,
including.

One aspect of the vehicle control device including the exhaust gas purification device of the present invention is
An estimation unit that estimates the amount of _{CO 2} and N ₂ O contained in the exhaust gas of an internal combustion engine,
A ratio calculation unit that calculates the ratio of N ₂ O to CO _{2 using the CO 2} and N ₂ O estimated by the estimation unit, and
Based on the ratio calculated by the ratio calculation unit, the _{N 2} O suppression unit that _{controls the suppression of N 2} O, and the N 2 O suppression unit.
To be equipped.

According to the present invention, in a vehicle having an exhaust gas purifying device can suppress the emission of N 2 _O.

The figure which showed the main part structure of the exhaust gas purification apparatus of embodiment Of ECU configuration block diagram showing a part related to the N 2 _O estimated The figure which shows the structure of the estimation part The figure which shows the relationship between the LNT inlet temperature, the NOx storage amount, and the coefficient k1. The figure which shows the relationship between the LNT inlet λ value and the coefficient k2. Block diagram of the part related to emission control of N _{2 O} Flow chart showing an example of N _{2 O emission suppression control}

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

<1> diagram 1 of an exhaust purification device is a diagram showing a configuration of a main part of an exhaust gas purification apparatus 100 that N _{2 O} estimating method of this embodiment is applied. In the present embodiment, as an example, it will be described with embodiments of applying the N _{2 O} estimation method of the present invention the exhaust gas purification apparatus 100 of the diesel engine 10. However, N _{2 O} estimation method according to the present embodiment is not limited to the exhaust gas purification device 100 of the diesel engine 10 can be applied to the device for purifying exhaust gas of a gasoline engine.

The exhaust purification device 100 is mounted on a vehicle such as a truck, and purifies NOx in the exhaust gas of the engine 10.

The engine 10 includes, for example, a combustion chamber, a fuel injection device that injects fuel in the combustion chamber, an engine ECU that controls the fuel injection device, and the like (not shown). The engine 10 generates power by burning and expanding a mixture of fuel and air in a combustion chamber. The engine 10 is connected to an intake pipe 20 that introduces air into the combustion chamber and an exhaust pipe 30 that discharges the exhaust gas after combustion discharged from the combustion chamber to the outside of the vehicle.

The exhaust gas purification device 100 includes a DOC (Diesel Oxidation Catalyst) 101, a DPF (Diesel Particulate Filter) 102, an LNT (Lean NOx Trap) 103 as a NOx storage reduction catalyst, an SCR (Selective Catalytic Reduction) 104, and a urea water injection device 105. Has.

The DOC 101 oxidizes and purifies CO and HC in the exhaust gas in a state where the air-fuel ratio of the exhaust gas is lean (that is, during normal combustion of the engine 10).

The DPF 102 collects particulate matter contained in the exhaust gas.

The LNT 103 occludes NOx in the exhaust gas in a state where the air-fuel ratio of the exhaust gas is lean. Then, the LNT 103 reacts the occluded NOx with CO or HC in the exhaust gas in a state where the air-fuel ratio of the exhaust gas is rich (that is, at the time of regeneration) and reduces it to a harmless gas such as nitrogen. discharge. The efficiency with which NOx can be occluded decreases as the LNT 103 approaches the saturated state. Therefore, the NOx storage state of the LNT 103 is monitored by the ECU 110, and the LNT 103 is periodically regenerated (also referred to as a rich spike).

The SCR 104 adsorbs ammonia formed by hydrolyzing urea water supplied from the urea water injection device 105, and selectively reduces and purifies NOx from the exhaust gas by the adsorbed ammonia.

Further, the exhaust gas purification device 100 has an ECU (Electronic Control Unit) 110. The ECU 110 controls the operation of the exhaust gas purification device 100. Further, the ECU 110 sends information on the storage state of NOx of the LNT 103 to the engine ECU (not shown) of the engine 10. The engine ECU performs rich control and the like to realize rich spikes based on this information.

The ECU 110 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, an output port, and the like. Each function described later in the ECU 110 is realized, for example, by the CPU referring to a control program or various data stored in a ROM, RAM, or the like. However, it goes without saying that the function is not limited to processing by software, but can also be realized by a dedicated hardware circuit.

The ECU 110 controls the engine ECU (not shown) of the engine 10 and the urea water injection device 105 and the like, and acquires these states. Further, the ECU 110 acquires sensor information from various sensors (not shown), and detects the state of the exhaust gas flowing through the exhaust pipe 30, the state of the DOC101, the DPF102, the LNT103, the SCR104, and the like based on the sensor information.

<2> _{Estimation of N 2} O Next, the estimation of N ₂ O according to the present embodiment will be described.

The inventors of the present invention, by past experience, the generation of N 2 _O is NOx / SOx occlusion amount of LNT, during the rich lambda, and has obtained a finding catalyst temperature is dominant.

As a result of such findings and studies, the inventor _{has found that N 2} O can be estimated _{based on the O 2} amount and temperature of the exhaust gas flowing into the LNT, and the NOx occlusion amount and the SOx occlusion amount of the LNT. It was.

Specifically, as a base map of the N 2 _O slip, by correcting the above four parameters as a coefficient, it becomes possible to accurately estimate the amount of slip of N _{2 O} in the rich. The calibration value may be obtained experimentally.

Of the above four parameters, the _{amount of O 2} and the temperature are acquired by the existing λ sensor and temperature sensor at the LNT inlet. Further, the NOx occlusion amount, SOx occlusion amount and internal temperature of LNT can be obtained by calculation by a known method.

In this embodiment, the estimation processing of the _{N 2} O takes place in ECU 110. However, _{the processing of N 2} O is not limited to the ECU 110, and for example, an independent processing unit for estimating _{N 2 O may be provided.}

2, of the configuration of the ECU 110, is a block diagram showing a part related to the _{N 2} O estimated.

The ECU 110 includes an acquisition unit 111 that acquires information from various sensors provided in the exhaust gas purification device 100, and an estimation unit 112 that estimates the amount of _{N 2 O flowing downstream from the LNT 103 using the acquired information.} Have.

In the case of the present embodiment, the acquisition unit 111 is charged with the LNT inlet temperature from the temperature sensor 41 provided at the inlet of the LNT 103, the LNT inlet λ value from the λ sensor 42, and the flow rate sensor 43 provided at the intake pipe 20. , The NOx concentration from the NOx sensor 44 provided on the downstream side of the LNT 103, and the fuel flow rate from the fuel flow meter (not shown) are input.

FIG. 3 shows the configuration of the estimation unit 112.

The estimation unit 112
NOx slip base map 201 as a base value output unit that outputs the base value _{of the N 2} O slip estimator from the LNT 103;
A correction coefficient map 202 based on the NOx storage amount that outputs the first correction coefficient k1 based on the LNT inlet temperature and the NOx storage amount;
The correction coefficient table 203 by _{O 2} that outputs the second correction coefficient k2 based on the λ value at the entrance of the LNT 103 (in other words, the _{amount of O 2 at the entrance of the LNT 103);}
A correction coefficient table 204 based on the SOx occlusion that outputs a third correction coefficient k3 based on the SOx occlusion;
A temperature-based correction factor table 205 that outputs a fourth correction factor k4 based on the LNT internal estimated temperature;
A multiplication unit that multiplies the base value output from the NOx slip base map 201 by the first, second, third, and fourth correction coefficients k1 to k4;
Have.

With such a configuration, the estimation unit 112 _{corrects the base value of the N 2} O slip estimate by the coefficients k1 to k4, so that the corrected N ₂ O slip amount (that is, the N ₂ O flowing downstream from the LNT 103) Amount).

Here, the exhaust gas flow rate (kg / h) referred to in the NOx slip base map 201 includes, for example, the intake air flow rate obtained by the flow rate sensor 43, the fuel weight obtained by the fuel flow meter (not shown), and the fuel weight. Can be obtained by adding.

The NOx storage amount referred to in the NOx storage amount correction coefficient map 202 can be obtained by calculation from, for example, the exhaust gas flow rate and the NOx concentration obtained by the NOx sensor 44. The NOx storage amount can also be calculated from a map created from the values obtained in the experiment.

In the case of this embodiment, the exhaust gas flow rate, the NOx storage amount, and the SOx storage amount are calculated by the acquisition unit 111.

Incidentally, in the present embodiment, the NOx sensor 44 is provided on the downstream side of the LNT 103, but the position of the NOx sensor is not limited to this. The NOx sensor may be provided near the outlet of the engine 10, for example.

Correction coefficient for SOx occlusion The SOx occlusion referred to in Table 204 can be estimated from the fuel flow rate obtained by a fuel flow meter (not shown). That is, the SOx occlusion amount can be calculated from the fuel consumption amount and the sulfur concentration in the fuel.

Correction coefficient by temperature The estimated LNT internal temperature referred to in Table 205 can be estimated from, for example, the inlet temperature of LNT 103, taking into account the time response delay of temperature transmission.

In the example of FIG. 3, is from the NOx slip base map 201, if and exhaust gas flow rate at LNT inlet temperature 200 [° C] is 100 [kg / h], as the base value for _{N 2} O slip estimator 10 [ mg / s] is output. Incidentally, in the example of FIG. 3, 10 [mg / s] is output as the base value _{of the N 2 O slip estimated amount at all LNT inlet temperatures and all exhaust gas flow rates.}

Further, as can be seen from FIG. 3, from the correction coefficient map 202 based on the NOx storage amount, 0 is output as the coefficient k1 when the NOx storage amount is 0. On the other hand, when the NOx storage amount is other than 0, the higher the LNT inlet temperature, the closer the coefficient k1 is to 1.

Further, as can be seen from FIG. 3, the coefficient k2, which is smaller as the LNT inlet λ value is closer to 1, is output from the correction coefficient table 203 by _{O 2.}

Further, as can be seen from FIG. 3, from the correction coefficient table 204 based on the SOx occlusion amount, a coefficient k3 closer to 1 is output as the SOx occlusion amount increases. However, unlike the correction coefficient map 202 based on the NOx storage amount, even if the SOx storage amount is 0, a coefficient k3 of 0 or more is output.

Further, the temperature correction coefficient table 205 is formed so that the coefficient k4 of the LNT internal temperature at which _{N 2 O is most likely to be generated is 1.} For example, in general, since LNT internal temperature is the peak of the generation of _{N 2} O in the vicinity 250 [° C], the correction coefficient table 205 with temperature, outputs the coefficient k4 is close to 1 the closer to 250 [° C] It is formed like this.

The numerical values in the map and table in FIG. 3 are examples, and these numerical values can be changed depending on the configuration and characteristics of the apparatus.

Also, FIG. 3 shows only very fragmentary numbers for the sake of simplicity, but in reality more numbers are stored in the maps and tables.

For example, the correction coefficient map 202 based on the NOx storage amount shows only 200 [° C] and 500 [° C] as the LNT inlet temperature, and only 0 [g] and 10 [g] as the NOx storage amount. However, in reality, the coefficient k1 corresponding to values other than these is also stored in the correction coefficient map 202 based on the NOx storage amount. Incidentally, the relationship between the LNT inlet temperature, the NOx storage amount, and the coefficient k1 is as shown in FIG. Therefore, based on the relationship of FIG. 4, the coefficient k1 corresponding to a value other than the above-mentioned value may be stored in the map, or the coefficient k1 may be obtained by calculation based on the relationship of FIG. ..

Similarly, the _{correction coefficient table 203 by O 2} shows only 0.9 and 1 as the LNT inlet λ value, but in reality, the _{correction coefficient table 203 by O 2} shows values other than these. The corresponding coefficient k2 is also stored. Incidentally, the relationship between the LNT inlet λ value and the coefficient k2 is as shown in FIG. Therefore, based on the relationship of FIG. 5, the coefficient k2 corresponding to the λ value other than the above-mentioned value may be stored in the table, or the coefficient k2 may be obtained by calculation based on the relationship of FIG. Good.

The correction coefficients k1 to k4 in FIG. 3 are set based on the following considerations.
As-occlusion amount of NOx is large _{N 2} O production in many cases.
-The larger the λ value, the more N ₂ O is generated.
As the storage amount of · SOx often _{N 2} O production in many cases.
- Experiments, LNT internal temperature has been found that a peak of _{N 2} O generated when approximately 250 [° C].

Thus, in the present embodiment, the amount of _{O 2} and temperature of the exhaust gas flowing into the LNT103, the NOx occlusion amount and the SOx storage amount of LNT103, an acquiring unit 111 for acquiring, these _{O 2} amount, temperature, _{An estimation unit 112 that estimates N 2} O based on the NOx storage amount and the SOx storage amount is provided, and the amount of _{N 2} O flowing downstream from the LNT 103 in the exhaust gas purification device 100 is estimated. _{It is possible to realize an N 2} O estimation device that can estimate the amount of _{N 2} O emissions while effectively utilizing the sensors of.

Further, the estimation unit 112 outputs a base value output unit (NOx slip base map 201) for outputting the base value _{of the N 2} O slip estimation amount from the LNT 103, and a first correction coefficient based on the temperature and the NOx occlusion amount. a correction factor map 202 according to NOx occlusion amount that outputs k1, the correction coefficient table 203 by _{O 2} for outputting a second correction coefficient k2 that is based on the amount of _{O 2,} the SOx third correction factor based on the storage amount k3 a correction coefficient table 204 by the SOx occlusion amount that outputs, to the base value, the first, a calculation unit for obtaining an estimate of N _{2 O} by multiplying the second and third correction coefficients k1 to k3, because it has a, it can be obtained easily _{N 2} O slip amount after correction (i.e. the amount of _{N 2} O flowing from LNT103 downstream).

<3> _{N 2} O emissions control then, the described _{N 2} O emissions control according to this embodiment.

6, of the configuration of the ECU 110, is a block diagram showing a portion related to emissions control of _{N 2} O.

The acquisition unit 111 is the same as the acquisition unit 111 of FIG. 2, and the LNT inlet temperature, the LNT inlet λ value, the intake air flow rate, the NOx concentration, and the fuel flow rate are input.

In addition to the processing of the estimation unit 112 of FIG. 2, the estimation unit 112a estimates the amount of _{CO 2 contained in the exhaust gas based on, for example, the fuel flow rate.} As a result, the estimation unit 112a estimates the amount of _{N 2} O and CO ₂ contained in the exhaust gas, and outputs the _{N 2} O estimated value and the CO _{2 estimated value.} Practically, what is estimated by the estimation unit 112a is the _{amount of N 2} O emitted per unit time and the amount of CO ₂ emitted per unit time.

Ratio calculation unit 113, by using a CO ₂ estimates and _{N 2} O estimates to calculate the ratio of _{N 2} O estimates for CO ₂ estimates. At this time, in this embodiment, the ratio calculation unit 113, after multiplying the warming potential N 2 _O estimates, calculates the ratio. That, _{N 2} O considers that there is influence corresponding to 300 times the CO ₂ as warming materials, multiplied by a factor of about 300 to _{N 2} O estimates. Therefore, the ratio calculation unit 113 calculates (N ₂ O estimated value × 300 / CO ₂ estimated value) as a ratio. Actually, the ratio calculation unit 113 outputs the calculated ratio by time averaging (for example, performing a time averaging of about 10 seconds).

The N _{2 O suppression unit 114 performs N 2} O suppression control based on the ratio calculated by the ratio calculation unit 113. Here, N 2 _O emissions in can be achieved by limiting the rich control of the engine. Therefore, the N ₂ O suppression control of the present embodiment is a control that prohibits rich control, a control that reduces the frequency of rich control, and a control that increases the exhaust gas air-fuel ratio during rich control (that is, less fuel). Control). In the present embodiment, suppression control of the N _{2 O} to (may be referred to as the rich control limits), and performs, based on the ratio.

Specifically, N _{2 O} suppression unit 114 of the present embodiment is different from the ratio calculated by the ratio calculating section 113, using a threshold of bounds set, implementing the following control. Here, the upper and lower threshold values are values in an allowable range as the amount of _{N 2 O emitted.} For example, 10% is set as the upper limit threshold value, and 5% is set as the lower limit threshold value.

-If the ratio is higher than the upper threshold, rich control is prohibited.
-If the ratio is lower than the lower threshold, rich control is not prohibited.

Figure 7 is a flowchart showing an example of emissions control N 2 _O.

First, in step S11, the estimation unit 112a _{calculates the N 2} O estimated value and the CO ₂ estimated value. Ratio calculation unit 113 In step S12, calculates the CO ₂ converted emissions _{N 2} O (multiplied by warming potential _{N 2} O estimates as described above). Ratio calculation unit 113 at the subsequent step S13 to calculate the ratio of _{N 2} O estimates for CO ₂ estimates (CO ₂ conversion value).

In step S14, _{N 2} O suppression unit 114, the ratio is determined whether or not than the lower limit threshold value. If the ratio is below the lower threshold (step S14; YES), the process shifts to a step S15, _{N 2} O suppressing section 114 does not prohibit the rich control. That is, the rich spike is performed as usual.

In contrast, when the ratio is larger than the lower threshold (step S14; NO), the process shifts to a step S16, _{N 2} O suppression unit 114 ratio is determined whether or not more than the upper threshold. If the ratio is greater than the upper threshold (step S16; YES), the process shifts to a step S17, _{N 2} O suppression unit 114 prohibits the rich control. That is, the engine ECU (not shown) or the like is instructed to prohibit rich spikes.

When the ratio is smaller than the upper limit threshold value (step S16; NO) and after the processing of step S17, the process returns to step S14.

Thus, _{N 2} O suppression unit 114, when the ratio is smaller than the larger upper threshold than the lower threshold, repeating the loop of steps S14-S16-S14, does not participate in the rich control. Further, N 2 _O suppression unit 114, even if the ratio is temporarily prohibited rich control at step S17 becomes equal to or more than the upper limit threshold value, if the ratio is equal to or less than the lower limit threshold value in step S14, the prohibition of rich control by step S15 To cancel.

N _{2 O} suppression process of this embodiment, by setting the lower limit threshold and the upper threshold has a hysteresis to prohibit the release of the rich control. As a result, it is possible to prevent the engine control from becoming unstable due to the frequent prohibition and cancellation of rich control.

<4> Summary As described above, according to the present embodiment, the estimation unit 112a for estimating the amount of _{CO 2} and N _{2 O contained in the exhaust gas of the internal combustion engine and the CO estimated by the estimation unit 112a} A ratio calculation unit 113 that calculates the ratio of N ₂ O to CO _{2 using 2} and N ₂ O, and an N ₂ O suppression unit _{that controls N 2} O suppression based on the ratio calculated by the ratio calculation unit 113. and 114, by the provided, it becomes possible to satisfactorily suppress the emission of N 2 _O. In other words, according to this embodiment, while suppressing the emission of greenhouse gases while managing emissions ratio of N 2 _O in the allowable range, it is possible to maintain the NOx purification rate.

It can be said that the N ₂ O suppression unit 114 of the present embodiment increases the intensity of _{N 2} O suppression control as the ratio of the N _{2 O estimated value to the CO 2 estimated value increases.}

The above-described embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

In the above-described embodiment, as N ₂ O suppression control, based on the ratio of N _{2 O to CO 2} , rich control is prohibited, the frequency of rich control is reduced, and the exhaust gas air-fuel ratio during rich control is increased. it is described for controlling the like, suppression control of the N _{2 O} of the present invention is not limited thereto.

For example, in step S15, instead of performing control that does not prohibit rich control, control such as increasing the temperature at which rich reduction efficiency is good and the rich frequency at λ may be performed.

Further, in step S17, instead of prohibiting the rich control may be performed to control to decrease the frequency of the rich control in a temperature range of N 2 _O production is increased (e.g., 220-300 [° C]) .. Further, in step S17, instead of prohibiting the rich control, the control may be performed to correct the target λ value at the time of the rich control to a value with _{less N 2 O generation.} Further, in step S17, instead of prohibiting the rich control, control may be performed in which the frequency of the rich control is restricted based on the NOx or SOx occlusion amount. For example, if the SOx occlusion amount is large, since N 2 _O increases, it may perform control to decrease the frequency of the rich control. Incidentally, in step S15, the control opposite to these controls may be performed.

The _{method for estimating the amount of CO 2} and N ₂ O is not limited to the method of the above-described embodiment.

For example, in the above-described embodiment, the exhaust gas flow rate were also considered, since N 2 _O slip amount is not largely dependent on the change in the exhaust gas flow rate, gas flow rate may be assumed to be constant.

Further, in the embodiment described above, but also taking into account the internal temperature of LNT103, that is, although using the coefficient k4 is provided a correction coefficient table 205 with temperature, effect on N _{2 O} amount of LNT internal temperature of 3 As you can see, the internal temperature may not be taken into consideration because it is small compared to other factors. That is, k4 may be a constant value.

Further, in the above-described embodiment, the case where the λ value obtained by the λ sensor 42 is used as an index _{of the O 2 amount of the exhaust gas flowing into the LNT 103 has been described, but instead of the λ sensor 42, another O 2} sensor is used. The output value may be used.

Further, in the above-described embodiment, the _{amount of N 2} O slip from the LNT 103 has been described, but when SCR or CSF (Catalyzed Soot Filter) is provided, the same logic as described above is applied to these. Te seek N _{2 O} estimates may be N _{2 O} estimates are discharged cumulated N _{2 O} estimates from the final tail pipe. In this case, the logic may be modified according to each catalyst. For example, CSF and SCR do not require a correction coefficient map based on NOx occlusion, _{a correction coefficient table based on O 2, and} a correction coefficient table based on SOx occlusion.

The present invention has an effect capable of suppressing the emission of N _{2 O} in the exhaust purification apparatus is suitable for a vehicle having an exhaust gas purification device.

10 Engine 20 Intake pipe 30 Exhaust pipe 41 Temperature sensor 42 λ sensor 43 Flow sensor 44 NOx sensor 100 Exhaust purification device 101 DOC (Diesel Oxidation Catalyst)
102 DPF (Diesel Particulate Filter)
103 LNT (Lean NOx Trap; NOx storage reduction catalyst)
104 SCR (Selective Catalytic Reduction)
105 Urea water injection device 110 ECU (Electronic Control Unit)
111 Acquisition unit 112, 112a Estimating unit 113 Ratio calculation unit 114 N ₂ O Suppressing unit 201 NOx slip base map 202 NOx correction coefficient map by occlusion 203 O ₂ correction coefficient table 204 SOx correction coefficient table by occlusion amount 205 Correction by temperature Coefficient table

Claims (7)

It is a control method for vehicles equipped with an exhaust purification device.
An estimation step for estimating the amount of _{CO 2} and N ₂ O contained in the exhaust gas of an internal combustion engine, and
Using the CO ₂ estimated value estimated by the estimation step and N _{2 O} estimates, the ratio calculation step of calculating the ratio of N _{2 O} estimates for CO ₂ estimates,
Based on the ratio calculated by said ratio calculating step, and N _{2 O} suppression step of suppressing control of N 2 _O,
Control methods including. In the N ₂ O suppression step, the greater the ratio of the N _{2 O estimated value to the CO 2} estimated value, the greater the intensity of the _{N 2 O suppression control.}
The control method according to claim 1. The N ₂ O suppression step terminates the suppression control when the ratio of the N _{2 O estimated value to the CO 2} estimated value is equal to or less than a predetermined threshold value.
The control method according to claim 1 or 2. The suppression control is a control that reduces the frequency of rich control.
The control method according to any one of claims 1 to 3. The suppression control is a control for increasing the exhaust gas air-fuel ratio during rich control.
The control method according to any one of claims 1 to 3. In the ratio calculation step, the N ₂ O estimated value calculated in the estimation step is multiplied by a warming coefficient, and the N ₂ O estimated value obtained by multiplying the warming coefficient is used to calculate the ratio.
The control method according to any one of claims 1 to 5. A vehicle control device equipped with an exhaust purification device.
An estimation unit that estimates the amount of _{CO 2} and N ₂ O contained in the exhaust gas of an internal combustion engine,
A ratio calculation unit that calculates the ratio of N ₂ O to CO _{2 using the CO 2} and N ₂ O estimated by the estimation unit, and
Based on the ratio calculated by the ratio calculation unit, the _{N 2} O suppression unit that _{controls the suppression of N 2} O, and the N 2 O suppression unit.
A control device comprising.

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