WO2013073512A1

WO2013073512A1 - Fuel injection method for internal combustion engine and internal combustion engine

Info

Publication number: WO2013073512A1
Application number: PCT/JP2012/079331
Authority: WO
Inventors: 英和藤江; 哲史塙
Original assignee: いすゞ自動車株式会社
Priority date: 2011-11-18
Filing date: 2012-11-13
Publication date: 2013-05-23
Also published as: JP2013108408A; JP5790436B2

Abstract

In the present invention, the deviation value is calculated between an actual air excess ratio, which is calculated from the oxygen concentration value of an NOx sensor provided downstream of an exhaust gas purification device provided to an exhaust pathway, and a target air excess ratio, which is calculated from an actual designated fuel injection amount and a new air amount detected by an MAF sensor provided to an air intake pathway; the result is recorded to a learning region map having the common rail pressure and the designated fuel injection amount as a base; the current learning value corresponding to the current common rail pressure and the current designated fuel injection amount is corrected in a manner so that the deviation value becomes zero and a new learning value is calculated and, at the time of fuel injection from an injector, recorded to an electrification time map having the designated fuel injection amount and common rail pressure as a base; the current injection time, which corresponds to the current designated fuel injection amount and the current common rail pressure, is corrected by the new learning value; and fuel injection is performed; by which means, using an NOx sensor, the deviation between the designated fuel injection amount and the actual fuel injection amount resulting from injector degradation and the like is corrected.

Description

[Supplement based on Rule 26 30.11.2012] Fuel injection method of internal combustion engine and internal combustion engine

The present invention uses the oxygen concentration of a NOx sensor provided downstream of the exhaust gas purification device, and corrects the fuel injection of the internal combustion engine that can be corrected so as to eliminate the difference between the actual fuel injection amount and the commanded fuel injection amount. The present invention relates to a method and an internal combustion engine.

Conventionally, in an engine (internal combustion engine), an ECU (control device) controls an injector (fuel injection valve) to adjust the fuel injection amount from the injector to an appropriate amount. The command fuel injection amount adjusted to an appropriate amount is determined so as to improve fuel consumption, reduce harmful components of exhaust gas, and reduce noise.

However, various problems occur when the fuel injection system including the injector is deteriorated or malfunctioned and the indicated fuel injection amount deviates from the amount actually injected by the injector. For example, when the actual injection amount is smaller than the commanded fuel injection amount, the required torque is not obtained and the travel is hindered. On the other hand, when the actual injection amount is larger than the commanded fuel injection amount, Problems such as an increase in fuel pressure, engine failure, fuel consumption deterioration, and an increase in the concentration of harmful components in exhaust gas occur.

Therefore, an excess air ratio sensor or an excess air ratio sensor (such as an oxygen sensor also called a lambda sensor or an A / F sensor called an A / F sensor) that can measure the excess air ratio or the air / fuel ratio is used to measure the exhaust gas from the target air / fuel ratio. An apparatus that corrects the deviation amount of the air-fuel ratio (for example, see Patent Document 1) and an apparatus that compares and corrects the excess air ratio in the exhaust gas, the command injection quantity, and the excess air ratio calculated from the fresh air quantity Yes (see, for example, Patent Document 2).

These devices detect an excess air ratio in the exhaust gas or an air-fuel ratio of the exhaust gas by an excess air ratio sensor provided upstream of the exhaust gas treatment device or upstream and downstream of the exhaust gas treatment device. The detected excess air ratio or air / fuel ratio depends on the actual fuel injection amount. By correcting the deviation between this and the target value obtained from the indicated fuel injection amount, or comparing the deviations, abnormal fuel injection is detected. By detecting this, the injector is monitored and controlled so that the actual fuel injection amount and the command fuel injection amount do not deviate.

The air excess rate sensor provided in the above apparatus is, for example, ZrO ₂ (zirconia) or TiO ₂ (titania) which is provided upstream of the exhaust gas processing apparatus and has electrodes with Pt (platinum) coating on the inner and outer surfaces. It is formed with a solid electrolyte tube formed by, for example.

The principle of this excess air ratio sensor is that oxygen ions flow from the atmosphere side where the oxygen partial pressure is high toward the exhaust gas side where the oxygen partial pressure is low, thereby generating an electromotive force proportional to the logarithm of the oxygen partial pressure ratio between the electrodes. The oxygen concentration in the exhaust gas is detected from the electromotive force.

By using the above-described device equipped with this excess air ratio sensor, it is possible to correct the deviation between the actual fuel injection amount and the commanded fuel injection amount, or to detect an abnormality in fuel injection by comparing the deviations. However, since the excess air ratio sensor uses Pt or ZrO ₂ , the sensor is expensive. Therefore, since the manufacturing cost increases, only a few engines are equipped with an excess air ratio sensor.

On the other hand, many recent engines are equipped with an exhaust gas purification device to clean exhaust gas. This engine is provided with a NOx sensor for measuring the content of NOx (nitrogen oxide) in the exhaust gas downstream of the exhaust gas purification device.

This NOx sensor is, for example, a sensor that is provided downstream of an exhaust gas treatment device and is made of a ceramic solid electrolyte (oxygen ion conductor) that is excellent in durability and heat resistance, and has at least two compartments. The exhaust gas is exhausted by the first oxygen pump by using a first oxygen pump that removes oxygen other than NOx in one compartment and a second oxygen pump that decomposes NOx and removes the generated oxygen in the other compartment. The oxygen concentration in the exhaust gas is detected, and the NOx concentration in the exhaust gas is detected by the second oxygen pump.

Similar to the above-described excess air ratio sensor, the NOx sensor uses oxygen ion conductors (SnO ₂ , ITO, YBCO, WO ₃ , TiO ₂ , ZrO ₂ , Zn ₂ SnO _4, etc.), and Pt, Rh on the surface thereof. Since it is processed by applying (rhodium) or the like, the sensor is expensive.

However, this NOx sensor is a method for directly detecting the NOx occlusion state of the NOx occlusion reduction catalyst in the exhaust gas purification device and giving an optimum timing for reducing agent charging control, or a method for diagnosing deterioration of the catalyst on the vehicle. It is a sensor that is indispensable for providing an exhaust gas purifying device in an engine.

JP-A-11-82117 JP 10-141125 A

The present invention has been made in view of the above-described problems, and an object of the present invention is to use a NOx sensor provided downstream of the exhaust gas purification device without adding an expensive excess air ratio sensor, and to deteriorate the injector. To provide a fuel injection method for an internal combustion engine and an internal combustion engine capable of correcting the next fuel injection time so that the deviation between the actual fuel injection amount generated due to the fuel injection and the instructed fuel injection amount becomes zero It is.

The fuel injection method for an internal combustion engine according to the present invention for solving the above-described object is a fuel injection method for an internal combustion engine in which an exhaust gas purification device is provided in an exhaust passage, and a NOx sensor provided downstream of the exhaust gas purification device. A deviation value between the actual excess air ratio λ1 calculated from the oxygen concentration value and the target excess air ratio λ2 calculated from the fresh air amount detected by the intake air amount sensor provided in the intake passage and the current commanded fuel injection amount is calculated. The deviation value is zero for the current injection time correction value stored in the injection time correction value map based on the common rail pressure and the commanded fuel injection amount and corresponding to the current common rail pressure and the current commanded fuel injection amount. Thus, the injection time correction value is calculated, and when the fuel is injected from the fuel injection valve, it is stored in the injection time map based on the common rail pressure and the indicated fuel injection amount, and the current common level is calculated. The fuel injection is performed by correcting the current injection time corresponding to the fuel pressure and the current commanded fuel injection amount with the injection time correction value.

According to this method, by using the NOx sensor provided downstream of the exhaust gas purification device including the SCR device (selective catalytic reduction device), the fuel injection time of the injector (fuel injection valve) is changed to the actual fuel injection amount. Therefore, the difference between the actual fuel injection amount and the command fuel injection amount can be eliminated. As a result, the deviation between the actual fuel injection amount and the commanded fuel injection amount due to the deterioration of the injector or the like can be made zero without adding an excess air ratio sensor that was conventionally necessary for correcting the fuel injection amount. As a result, the number of parts can be reduced, and the manufacturing cost can be reduced.

In addition, the fuel injection time based on the commanded fuel injection amount and the rail pressure (fuel injection pressure) of the common rail is corrected with the injection time correction value, and the pulse width of the injection time of the injector is corrected. The amount can be directed to the injector.

In the fuel injection method for the internal combustion engine, the injection time correction value is expressed by the following equation (1) using the actual excess air ratio λ1, the target excess air ratio λ2, and the current injection time correction value. The injection time is obtained by the following equation (2) using the current injection time and the injection time correction value.

However, L (i, j): current injection time correction value, L (I, J): injection time correction value, W_cor: weighting factor, T (i, j): current injection time, T_corr: injection time.

According to this method, by using the injection time correction value corrected so that the deviation between the actual excess air ratio λ1 and the target excess air ratio λ2 is 0, the pulse width of the injection time of the injector is corrected. The next commanded fuel injection amount can be corrected based on the fuel injection amount. As a result, without adding an excess air sensor, the fuel consumption deteriorates, the smoke emission increases, and the exhaust gas that occurs when the deviation between the actual fuel injection amount and the commanded fuel injection amount becomes large due to deterioration of the injector or the like. Heat damage such as exhaust pipes and turbochargers due to high gas temperatures can be prevented.

An internal combustion engine for solving the above problem is an internal combustion engine having an exhaust gas purification device provided in an exhaust passage, and an actual excess air ratio λ1 calculated from an oxygen concentration value of a NOx sensor provided downstream of the exhaust gas purification device. And means for calculating a deviation value between the fresh air amount detected by the intake air amount sensor provided in the intake passage and the target excess air ratio λ2 calculated from the current indicated fuel injection amount, and the common rail pressure and the indicated fuel injection amount. The injection time correction is performed by correcting the current injection time correction value stored in the base injection time correction value map and corresponding to the current common rail pressure and the current commanded fuel injection amount so that the deviation value becomes zero. The means for calculating the value and the fuel injection from the fuel injection valve are stored in an injection time region map based on the common rail pressure and the indicated fuel injection amount, and the current common rail pressure and the current indicator are stored. A control device is provided that includes means for correcting the current injection time corresponding to the indicated fuel injection amount with the injection time correction value and performing fuel injection.

Further, in the above internal combustion engine, the control device uses the actual air excess rate λ1, the target air excess rate λ2, and the current injection time correction value as the injection time correction value using the following equation (3): ) And means for obtaining the injection time by the following equation (4) using the current injection time and the injection time correction value.

According to this configuration, the actual excess air ratio λ1 can be calculated from the output of the NOx sensor, and the next fuel injection time can be corrected from the actual fuel injection amount using the actual excess air ratio λ1. . As a result, it is not necessary to add an excess air ratio sensor that is conventionally required to eliminate the difference between the actual fuel injection amount and the command fuel injection amount, and thus the cost can be reduced.

According to the present invention, it is possible to use the NOx sensor provided downstream of the exhaust gas purification device without adding an expensive excess air ratio sensor and to indicate the actual fuel injection amount generated due to the deterioration of the injector and the designated fuel. The next fuel injection time can be corrected so that the deviation from the injection amount becomes zero.

FIG. 1 is a diagram showing an intake and exhaust system of an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the control of the internal combustion engine according to the embodiment of the present invention. FIG. 3 is a learning region map used in the fuel injection method for an internal combustion engine according to the embodiment of the present invention. FIG. 4 is an injection time region map used in the internal combustion engine fuel injection method according to the embodiment of the present invention. FIG. 5 is a flowchart showing a fuel injection method for an internal combustion engine according to the embodiment of the present invention.

Hereinafter, an internal combustion engine fuel injection method and an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, an in-line four-cylinder diesel engine will be described as an example. However, the present invention is not limited to this and may be applied to any internal combustion engine provided with a NOx sensor.

First, the configuration of an internal combustion engine according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, an engine (internal combustion engine) 1 includes a fuel supply system 4 including an injector (fuel injection valve) 3 for injecting fuel into each cylinder 2, an intake system 6 including an intake passage 5, and an exhaust passage. An exhaust system 8 including 7 is provided.

Fuel supply system 4 is a system that injects high-pressure fuel from injectors 3 connected to a common rail 9 that stores pressurized fuel, and includes a fuel tank and a supply pump (not shown). The intake system 6 includes an intake filter 10, an intercooler 11, and an intake throttle 12, and the exhaust system 8 is an exhaust gas purification system including a DPF (diesel particulate collection filter) 13 and an SCR device (selective catalytic reduction device) 14. A device 15 is provided.

Further, the intake system 6 and the exhaust system 8 can send the compressed air into the engine by rotating the turbine at high speed using the energy of the exhaust gas and driving the centrifugal compressor with the rotational force. The turbocharger 16, the EGR cooler 17, and the EGR valve 18 are provided with an EGR device (exhaust gas recirculation device) 19 that takes out a part of the exhaust gas after combustion, guides it to the intake side, and sucks it again.

The configuration of the engine 1 is a well-known configuration, and each device can use a well-known technique. In this embodiment, as long as the exhaust gas purification device 15 including at least the SCR device 14 is provided in the exhaust system 8, other configurations are not limited to the above configuration.

In addition, an ECU (control device) 20 that controls the above-described device and system, a NOx sensor 21, a MAF sensor (fresh air amount sensor) 22, and a pressure sensor 23 connected to the ECU 20 are provided. In addition, the engine 1 is provided with a sensor (not shown). However, in this embodiment, at least the sensors 21 to 23 are sufficient.

The ECU 20 is a control device called an engine control unit, and is a microcontroller that comprehensively performs electrical control in charge of control of the engine 1 by an electric circuit. As shown in FIG. Then, the fuel injection amount of the injector 3 is controlled. The ECU 20 includes an actual excess air ratio calculating means 24, a target excess air ratio calculating means 25, a learned value calculating means 26, and an injection time calculating means 27, and a learning region map (injection time correction value map) M1, energization A time map (injection time map) M2 and the current command fuel injection amount Q_fin are stored. Each of these means 24 to 27 is stored as a program in the ECU 20 and sequentially executed when correcting the fuel injection time.

The NOx sensor 21 provided downstream of the SCR device 14 is a sensor that measures the concentration value of NOx (nitrogen oxide) in the exhaust gas, and is a sensor that can measure the oxygen concentration value O2_exh in the exhaust gas. is there. The NOx sensor 21 is used in a method for directly detecting the NOx occlusion state of the NOx occlusion reduction catalyst in the SCR device 14 to give an optimum timing for reducing agent charging control, and a method for diagnosing deterioration of the catalyst on the vehicle. This sensor is necessary when the exhaust system 8 includes the SCR device 14.

The NOx sensor 21 is excellent in durability and heat resistance, and a known NOx sensor can be used as long as it can measure the NOx concentration in the exhaust gas and can measure the oxygen concentration value O2_exh in the exhaust gas. In addition, the MAF sensor 22 and the pressure sensor 23 may be well-known sensors if the MAF sensor 22 detects the fresh air amount m_air and the pressure sensor 23 can detect the common rail pressure (common rail pressure) P. it can.

Next, the operation of the engine 1 will be described with reference to FIG. 2, FIG. 3, and FIG. The engine 1 performs this operation every time a predetermined crank angle (for example, every 360 °) is reached. First, as shown in FIG. 2, using the oxygen concentration value O2_exh detected by the NOx sensor 21, the actual excess air ratio calculating means 24 provided in the ECU 20 calculates the actual excess air ratio λ1 from the following equation (5). calculate. Here, the oxygen concentration in the atmosphere is O2_air.

The actual excess air ratio calculating means 24 can calculate the actual excess air ratio λ1 derived from the actual fuel injection amount from the oxygen concentration value O2_exh detected by the NOx sensor 21. Thereby, in order to calculate the actual excess air ratio λ1, by using the NOx sensor 21 that needs to be provided in the engine 1 including the SCR device 14, it is not necessary to separately add an excess air ratio sensor. Therefore, the number of parts can be reduced, and the manufacturing cost can be reduced.

Next, using the current commanded fuel injection amount Q_fin stored in the ECU 20, the fresh air amount m_air detected by the MAF sensor 22, and the ideal air-fuel ratio AFR, the target excess air ratio calculating means 25 calculates the following equation (6 ) To calculate the target excess air ratio λ2.

Here, the ideal air-fuel ratio AFR takes various values depending on the properties of the fuel. For example, when the fuel is light oil, the value is about 14.5.

Next, the current learning value (current injection time correction value) L (i, j) stored in the learning area map M1 is corrected. Here, the learning area map M1 will be described. As shown in FIG. 3, the learning region map M1 is a map based on the common rail pressure P_area and the fuel flow rate (indicated fuel injection amount) Q_area stored in advance in the ECU 20.

The learning value (injection time correction value) L (i, j) stored in the learning area map M1 is a correction value for the injection time of the injector 3. In addition, the numerical value described in the learning area map M1 shown in FIG. 3 is a numerical value for explanation, and the actual numerical value is not limited to this. Further, the number of cells is not limited, and actually, a numerical value may be set finely to increase the number of cells.

Next, as shown in FIG. 2, the actual learning value (current injection time correction value) L (i, j) stored in the learning region map M1 is set to the actual excess air ratio λ1 and the target excess air ratio λ2. Using the deviation value Δλ and the weighting coefficient w_cor, the learning value calculation means 26 corrects the value from the following equation (7) to calculate the learning value (injection time correction value) L (I, J). .

Then, the learning value L (I, J) corrected so that the deviation value Δλ between the actual excess air ratio λ1 and the target excess air ratio λ2 becomes zero by the learned value calculating means 26 is learned as a new learned value. Store in the area map M1.

Next, the current injection time T (i, j) is corrected using the learning value L (I, J) calculated above. Here, the energization time map M2 will be described. As shown in FIG. 4, the energization time map M2 is a map based on the common rail pressure P_area and the fuel flow rate (indicated fuel injection amount) Q_area stored in advance in the ECU 20, and the energization time of the injector 3 stored therein. The unit of is (μs).

The current injection time T (i, j) stored in the energization time map M2 is the pulse width of the injection time during which the injector 3 injects fuel. In addition, the numerical value described in the energization time map M2 shown in FIG. 4 is a numerical value for description, and an actual numerical value is not limited to this. Further, the number of cells is not limited, and actually, a numerical value may be set finely to increase the number of cells.

Next, using the current injection time T (i, j) and the learned value L (I, J), the injection time calculation means 27 calculates the next injection time T_corr from the following equation (8).

Then, the ECU 20 controls the injector 3 to inject at the calculated injection time T_corr.

According to the above operation, the current learning value L (i, j) stored in the learning area map M1 is corrected so that the deviation value Δλ between the actual excess air ratio λ1 and the target excess air ratio λ2 is zero. By updating the learned value L (I, J), the deviation between the actual fuel injection amount and the commanded fuel injection amount due to deterioration of the fuel supply system 4 including the injector 3 can be corrected. Thereby, the deviation between the actual fuel injection amount and the command fuel injection amount can always be updated.

Further, the engine 1 can calculate the actual excess air ratio λ1 using the oxygen concentration value O2_exh of the NOx sensor 21 provided downstream of the SCR device 14 when the injector 3 injects fuel. Since the next fuel injection time T_corr can be corrected so that the deviation value Δλ between the excess air ratio λ1 and the target excess air ratio λ2 is zero, the deterioration of the injector 3 without adding an excess air ratio sensor. The deviation between the indicated fuel injection amount and the actual fuel injection amount can be corrected.

In addition, when the ECU 20 controls the injector 3, the current injection time T (i, j) of the indicated fuel stored in the energization time map M2 is used, so that the current common rail pressure P is set when the fuel is actually injected. Since the fuel is injected at the injection time T_corr based on it, it is possible to always make the indicated fuel injection amount accurate.

Next, the fuel injection method of the engine 1 will be described with reference to the flowchart of FIG. This fuel injection method is performed for each predetermined crank angle of the engine 1 and is corrected so that the injection time T_corr is based on the actual fuel injection amount of the injector 3.

First, step S11 for calculating the actual excess air ratio λ1 in the exhaust gas is performed using the oxygen concentration value O2_exh of the NOx sensor 21 provided downstream of the SCR device 14. In this step S11, the actual excess air ratio λ1 is calculated using the above equation (5), but it is only necessary to be able to determine the excess air ratio based on the actual fuel injection amount, and is not limited to the above method.

Next, Step S12 for calculating the target excess air ratio λ2 is performed using the MAF sensor 22 and the current command fuel injection amount Q_fin. In this step S12, the target excess air ratio λ2 is calculated using the above formula (6), but it is sufficient if the target excess air ratio λ2 obtained from the current command fuel injection amount Q_fin can be calculated. Not limited.

Next, step S13 for comparing the calculated actual excess air ratio λ1 with the target excess air ratio λ2 is performed. If λ1 = λ2 in step S13, the actual fuel injection amount and the current command fuel injection amount Q_fin coincide with each other, and the process proceeds to step S17 without correction. On the other hand, if λ1 ≠ λ2 in step S13, the actual fuel injection amount is deviated from the current commanded fuel injection amount Q_fin, so the process proceeds to step S14 and correction is performed.

If it is determined in step S13 that λ1 ≠ λ2, then step S14 for calling the current learning value L (i, j) from the learning region map M1 is performed. In step S14, the current learning value L (i, j) corresponding to the current common rail pressure P detected by the pressure sensor 23 and the current commanded fuel injection amount Q_fin is called. The learning value L (i, j) is a learning value used when the current command fuel injection amount Q_fin is corrected.

Next, using the deviation value Δλ between the actual excess air ratio λ1 and the target excess air ratio λ2, the current learning value L (i, j) is corrected to calculate the learning value L (I, J). I do. In this step S15, the learning value L (I, J) is calculated using the above mathematical formula (7). Next, step S16 of writing the learning value L (I, J) to the learning area map M1 is performed. At this time, the location of the cell written in the learning area map M1 is specified by the current common rail pressure P and the current commanded fuel injection amount Q_fin.

Next, Step S18 for calling the current injection time T (i, j) from the energization time map M2 is performed. In this step S18, the current injection time T (i, j) corresponding to the current common rail pressure P detected by the pressure sensor 23 and the current command fuel injection amount Q_fin is called.

Next, step S19 for calculating the next fuel injection time T_corr using the learned value L (I, J) and the current injection time T (i, j) is performed. In this step S19, the injection time T_corr is calculated using the above equation (8). When the next fuel injection time T_corr is calculated, the process returns to the start, and the above steps are repeated until the engine 1 stops. When the engine 1 is stopped, this fuel injection method is completed.

If it is determined in step S13 that λ1 = λ2, step S17 is performed in which the current learning value L (i, j) is set as the learning value L (I, J), and the process proceeds to steps S18 and S19. The fuel injection time T_corr is calculated, and the process returns to the start.

According to the fuel injection method described above, the command fuel injection time T_corr can be corrected using the oxygen concentration value O2_exh of the NOx sensor 21 in order to eliminate the difference between the actual fuel injection amount and the command fuel injection amount. Therefore, the difference between the actual fuel injection amount and the command fuel injection amount can be eliminated. As a result, without adding an excess air sensor, the fuel consumption deteriorates, the smoke emission increases, and the exhaust gas that occurs when the deviation between the actual fuel injection amount and the commanded fuel injection amount becomes large due to deterioration of the injector or the like. Thermal damage to the exhaust passage 7 and the turbocharger 16 due to the high temperature of the gas can be prevented.

Further, the learning value L (I, J) obtained by correcting the current learning value L (i, j) of the learning region map M1 so that the deviation value Δλ between the actual excess air ratio λ1 and the target excess air ratio λ2 becomes zero. By updating with the above, it is always possible to eliminate the difference between the actual fuel injection amount and the command fuel injection amount. According to this, even if the fuel injection time actually increases or decreases with respect to the instructed current injection time T (i, j) due to the deterioration of the injector 3, the injection time in which the increase / decrease is corrected It can be injected at T_corr. Therefore, it is possible to prevent a problem that occurs when the deviation between the actual fuel injection amount and the command fuel injection amount is large.

In addition, the fuel current injection time T (i, j) based on the current command fuel injection amount Q_fin and the current common rail pressure P of the common rail 9 is corrected by the learning value L (I, J), and the injection time pulse of the injector 3 is corrected. By correcting the width, a more accurate fuel injection time T_corr can be instructed to the injector, so that the difference between the actual fuel injection amount and the indicated fuel injection amount can be eliminated.

In this embodiment, an in-line four-cylinder diesel engine has been described as an example. However, by setting an ideal air-fuel ratio or the like to a value suitable for gasoline, it can also be applied to a gasoline engine equipped with an exhaust gas processing device. .

The internal combustion engine of the present invention can correct the deviation between the actual fuel injection amount and the commanded fuel injection amount by using a NOx sensor provided downstream of the exhaust gas processing device, so that it is particularly necessary to process the exhaust gas. It can be used for vehicles equipped with a diesel engine.

1 engine (internal combustion engine)
2 Cylinder block 3 Cylinder 4 Injector (fuel injection valve)
5 Intake pipe (intake passage)
6 Intake system 7 Exhaust pipe (exhaust passage)
8 Exhaust System 9 Common Rail 10 Intake Filter 11 Intercooler 12 Intake Throttle 13 DPF (Diesel Particulate Filter)
14 SCR device (selective catalytic reduction device)
15 Exhaust gas treatment device 16 Turbocharger 17 EGR device (exhaust gas recirculation device)
18 EGR cooler 19 EGR valve 20 ECU (control device)
21 NOx sensor 22 MAF sensor (fresh air sensor)
23 pressure sensor λ1 actual excess air ratio λ2 target excess air ratio M1 learning region map (injection time correction value map)
M2 Energizing time map (Injection time map)
L (i, j) Current learning value (current injection time correction value)
L (I, J) Learning value (injection time correction value)
T (i, j) Current injection time Q_fin Current command fuel injection amount T_corr Injection time O2_exh Oxygen concentration O2_air Atmospheric oxygen concentration m_air Fresh air intake amount AFR Ideal air-fuel ratio

Claims

In a fuel injection method for an internal combustion engine provided with an exhaust gas purification device in an exhaust passage,
Calculated from the actual excess air ratio λ1 calculated from the oxygen concentration value of the NOx sensor provided downstream of the exhaust gas purifying device, the fresh air amount detected by the intake air amount sensor provided in the intake passage, and the current commanded fuel injection amount The deviation value from the target excess air ratio λ2 is calculated,
The current injection time correction value stored in the injection time correction value map based on the common rail pressure and the commanded fuel injection amount and corresponding to the current common rail pressure and the current commanded fuel injection amount is set so that the deviation value becomes zero. To calculate the injection time correction value,
When fuel is injected from the fuel injection valve, the injection time map is stored based on the common rail pressure and the commanded fuel injection amount, and the current injection time corresponding to the current common rail pressure and the current commanded fuel injection amount is corrected to the injection time. A fuel injection method for an internal combustion engine, wherein the fuel injection is performed with correction by a value.
The injection time correction value is obtained by the following equation (1) using the actual excess air ratio λ1, the target excess air ratio λ2, and the current injection time correction value.
2. The fuel injection method for an internal combustion engine according to claim 1, wherein the injection time is obtained by the following equation (2) using the current injection time and the injection time correction value.

However,
L (i, j): Current injection time correction value L (I, J): Injection time correction value W_cor: Weight coefficient T (i, j): Current injection time T_corr: Injection time
In an internal combustion engine provided with an exhaust gas purification device in the exhaust passage,
Calculated from the actual excess air ratio λ1 calculated from the oxygen concentration value of the NOx sensor provided downstream of the exhaust gas purifying device, the fresh air amount detected by the intake air amount sensor provided in the intake passage, and the current commanded fuel injection amount Means for calculating a deviation value from the target excess air ratio λ2;
The current injection time correction value stored in the injection time correction value map based on the common rail pressure and the commanded fuel injection amount and corresponding to the current common rail pressure and the current commanded fuel injection amount is set so that the deviation value becomes zero. Means for calculating the injection time correction value,
When fuel is injected from the fuel injection valve, the injection time map is stored based on the common rail pressure and the commanded fuel injection amount, and the current injection time corresponding to the current common rail pressure and the current commanded fuel injection amount is corrected to the injection time. An internal combustion engine characterized by comprising a control device including means for performing fuel injection by correcting with a value.
Means for obtaining the injection time correction value by the following equation (3) using the actual excess air ratio λ1, the target excess air ratio λ2, and the current injection time correction value;
The internal combustion engine according to claim 3, further comprising means for obtaining the injection time by the following equation (4) using the current injection time and the injection time correction value.

However,
L (i, j): Current injection time correction value L (I, J): Injection time correction value W_cor: Weight coefficient T (i, j): Current injection time T_corr: Injection time