JP2003254040A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology in which capturing amount of particulates of a capturing mechanism is accurately determined, making an amount of intake air of an internal combustion engine as a parameter, in an exhaust emission control device for an internal combustion engine provided with a capturing mechanism for capturing the particulate in an exhaust gas and a variable nozzle type centrifugal supercharger. <P>SOLUTION: In the exhaust emission control device for the internal combustion engine provided with the capturing mechanism for capturing the particulate in the exhaust gas and the variable nozzle type centrifugal supercharger, it is characterized in that a nozzle opening of the variable nozzle type centrifugal supercharger is fully opened at the time of speed-reduction operation when the nozzle opening of the variable nozzle type centrifugal supercharger hardly influences to the operation state of the internal combustion engine and a determination of the capturing amount of the particulate making an amount of intake air of the internal combustion engine as a parameter is carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for purifying exhaust gas from an internal combustion engine, and more particularly to an exhaust gas purification technique provided with a mechanism for collecting fine particles contained in the exhaust gas.

[0002]

2. Description of the Related Art In recent years, internal combustion engines mounted on automobiles and the like have been required to have improved exhaust emissions. Particularly, in compression ignition diesel engines that use light oil as fuel, carbon monoxide (CO), hydrocarbons, etc. (HC), nitrogen oxides (NO
x) etc., as well as soot and SOF (Soluble O
Fine particles such as rganic fraction (PM: Particulate Mat)
ter) is required to be purified or removed.

Therefore, in a diesel engine, a particulate filter made of a porous base material having a large number of pores having a very small cross-sectional area is arranged in the exhaust passage, and exhaust gas is flowed through the pores of the particulate filter. By
A method of collecting PM in exhaust gas is known.

On the other hand, if the amount of trapped PM in the particulate filter is excessively increased, the exhaust resistance of the particulates may be increased and the back pressure acting on the internal combustion engine may be excessively increased accordingly. It is necessary to purify the PM trapped in the fill at an appropriate time to regenerate the PM trapping ability of the particulate filter.

In response to such a demand, in the past, Japanese Patent Laid-Open No.
An "exhaust gas purification device for an internal combustion engine" as described in Japanese Patent Laid-Open No. 001-158230 has been proposed. The exhaust gas purification apparatus for an internal combustion engine described in this publication preliminarily experimentally obtains the intake air amount when the internal combustion engine is in a predetermined operating state and the particulate filter is not clogged. Along with storing the intake air amount as a determination reference value, by comparing the intake air amount and the determination reference value when the internal combustion engine is in a predetermined operating state in the process of using the particulate filter,
This is intended to determine the PM collecting state of the particulate filter.

In this exhaust gas purifying apparatus for an internal combustion engine, when PM is trapped by the particulate filter, the pressure loss of the exhaust gas due to the particulate filter increases, so that the back pressure acting on the internal combustion engine rises. This is based on the finding that the intake air amount of the internal combustion engine decreases.

In an internal combustion engine equipped with a variable nozzle type centrifugal supercharger, the supercharging pressure of intake air and the back pressure of exhaust gas are changed according to the nozzle opening of the variable nozzle type centrifugal supercharger. Since it changes, the intake air amount of the internal combustion engine also changes according to the nozzle opening of the variable nozzle centrifugal supercharger.

Therefore, when the above-mentioned conventional technique is applied to an internal combustion engine equipped with a variable nozzle type centrifugal supercharger,
Since the intake air amount of the internal combustion engine changes not only with the PM trapping amount of the particulate filter but also with the nozzle opening of the variable nozzle centrifugal supercharger, the PM trapping amount of the particulate filter and the internal combustion engine It becomes difficult to establish a correlation with the intake air amount, and the PM collection amount determination accuracy may decrease.

The present invention has been made in view of the above situation, and is an internal combustion engine having a collecting mechanism for collecting fine particles in exhaust gas and a variable nozzle type centrifugal supercharger. An object of the present invention is to provide a technique capable of accurately determining the amount of fine particles collected by the mechanism.

[0009]

The present invention adopts the following means in order to solve the above problems. That is, an exhaust gas purification apparatus for an internal combustion engine according to the present invention is provided in a variable nozzle type centrifugal supercharger provided in an intake passage and an exhaust passage of the internal combustion engine and an exhaust passage of the internal combustion engine, and is included in exhaust gas. A collection mechanism for collecting fine particles, a control means for controlling the nozzle opening of the variable nozzle type centrifugal supercharger to be fully opened when the internal combustion engine is in a deceleration operation state, and the internal combustion engine is in a deceleration operation state. Yes, the detection means for detecting the intake air amount of the internal combustion engine when the nozzle opening of the variable nozzle type centrifugal supercharger is fully open, and the collection using the intake air amount detected by the detection means as a parameter. And an estimating means for estimating the amount of fine particles collected by the mechanism. The present invention relates to an exhaust gas purification apparatus for an internal combustion engine, which comprises a collecting mechanism for collecting fine particles in exhaust gas and a variable nozzle type centrifugal supercharger, wherein the nozzle opening of the variable nozzle type centrifugal supercharger is equal to that of the internal combustion engine. During deceleration operation that is unlikely to affect the operating state, the maximum opening of the variable nozzle type centrifugal supercharger is to fully open, and then the determination of the amount of collected particulates using the intake air amount of the internal combustion engine as a parameter is the maximum. It has a feature.

In such an exhaust gas purification apparatus for an internal combustion engine, when the internal combustion engine is in a decelerating operation state, the nozzle opening of the variable nozzle type centrifugal supercharger is controlled to be fully opened, and the intake air amount of the internal combustion engine at that time is used as a parameter. The amount of fine particles collected by the collection mechanism will be determined.

When the nozzle opening of the variable nozzle type centrifugal supercharger for determining the amount of collected fine particles of the collecting mechanism is fixed to be fully opened, the error caused by the nozzle opening of the variable nozzle type centrifugal supercharger is reduced. A change in the prepared intake air amount is prevented. As a result, the amount of intake air detected when determining the amount of fine particles collected by the collecting mechanism has an amount that correlates with the amount of fine particles collected by the collecting mechanism.

Therefore, when the particulate collection amount is determined with the intake air amount as a parameter when the internal combustion engine is in the decelerating operation state and the nozzle opening of the variable nozzle type centrifugal supercharger is fully opened, the determination accuracy is determined. Will be prevented.

When the intake throttle valve is provided in the intake passage of the internal combustion engine to which the present invention is applied, when the internal combustion engine is in the decelerating operation state, the nozzle opening and intake air of the variable nozzle centrifugal supercharger are increased. By fully opening the throttle valve,
The correlation between the intake air amount and the particulate collection amount may be established.

Further, when the EGR passage and the EGR valve are provided in the intake passage and the exhaust passage of the internal combustion engine to which the present invention is applied, the variable nozzle centrifugal supercharger when the internal combustion engine is in the deceleration operation state. The correlation between the intake air amount and the particulate collection amount may be established by fully opening the nozzle opening and the EGR valve opening.

When the internal combustion engine to which the present invention is applied is equipped with an intake throttle valve, an EGR passage, and an EGR valve, the nozzle of the variable nozzle type centrifugal supercharger when the internal combustion engine is in the decelerating operation state. The correlation between the intake air amount and the particulate collection amount may be established by fully opening the opening, the intake throttle valve, and the EGR valve.

Further, the exhaust gas purifying apparatus for an internal combustion engine according to the present invention comprises a judging means for judging that the trapping mechanism is clogged when the intake air amount detected by the detecting means falls below a predetermined amount. It may be further provided.

A method of controlling the opening degree of the nozzle of the variable nozzle type centrifugal supercharger to be fully closed may be considered when determining the amount of fine particles collected by the collecting mechanism.

However, in a normal internal combustion engine, since the variable nozzle type centrifugal supercharger is arranged in the exhaust passage upstream of the collecting mechanism, the nozzle opening can be changed when the nozzle opening is fully closed under such circumstances. The exhaust pressure upstream of the nozzle type centrifugal supercharger rises, while the exhaust pressure downstream of the variable nozzle type centrifugal supercharger decreases. That is, when the opening degree of the nozzle of the variable nozzle type centrifugal supercharger is fully closed, the pressure of the exhaust gas flowing into the collection mechanism decreases.

Here, when the trapping mechanism collects the fine particles, the resistance of the exhaust gas when passing through the trapping mechanism increases, so that the pressure loss and the back pressure of the exhaust gas due to the trapping mechanism increase. Accordingly, the intake air amount of the internal combustion engine decreases, but the pressure loss and the increase in back pressure at that time become more remarkable as the pressure of the exhaust gas flowing into the collection mechanism increases.

Therefore, when the pressure of the exhaust gas flowing into the collecting mechanism decreases due to the nozzle opening of the variable nozzle type centrifugal supercharger being fully closed, it is difficult for the exhaust gas pressure loss and back pressure to increase. At the same time, the amount of decrease in the intake air amount tends to decrease.

Further, the influence of the nozzle opening of the variable nozzle type centrifugal supercharger on the intake air amount is larger on the closed side than on the open side. Therefore, the actual nozzle opening when fully closed is controlled. If a slightly different situation occurs due to soot accumulation or the like, it is difficult to establish a correlation between the amount of collected particulates and the amount of intake air.

Considering these circumstances, it can be said that the method of determining the amount of collected fine particles using the amount of intake air when the nozzle opening of the variable nozzle type centrifugal supercharger is fully closed as a parameter is not appropriate.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Specific embodiments of an exhaust gas purification apparatus for an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine and an intake / exhaust system thereof to which an exhaust purification system according to the present invention is applied.

The internal combustion engine 1 shown in FIG. 1 is a compression ignition type diesel engine having four cylinders 2. In this internal combustion engine 1, a fuel injection valve 3 for injecting fuel directly into the combustion chamber of each cylinder 2 and a crankshaft that is an engine output shaft of the internal combustion engine 1 are rotated every predetermined angle (for example, 15 °). A crank position sensor 4 that outputs a pulse signal,
A water temperature sensor 5 that outputs an electric signal corresponding to the temperature of cooling water flowing through a water jacket (not shown) of the internal combustion engine 1 is attached.

The above-mentioned fuel injection valve 3 is connected to a pressure accumulating chamber (common rail) 7 via a fuel pipe 6. The common rail 7 is connected to a fuel pump 9 attached to a fuel tank 8 via a fuel pipe 10, and is also connected to a fuel tank 8 via a return pipe 11.

When the fuel pressure in the common rail 7 is lower than a preset maximum pressure, the connection portion of the common rail 7 to which the return pipe 11 is connected is closed to disconnect the conduction between the common rail 7 and the return pipe 11. A pressure adjusting valve 12 is provided which opens when the fuel pressure in the common rail 7 becomes equal to or higher than the maximum pressure and allows the common rail 7 and the return pipe 11 to conduct.

A fuel pressure sensor 13 that outputs an electric signal according to the fuel pressure in the common rail 7 is attached to the common rail 7.

In the fuel system thus constructed, the fuel pump 9 pumps up the fuel stored in the fuel tank 8,
The pumped fuel is pressure-fed to the common rail 7 through the fuel pipe 10. At that time, the fuel discharge amount of the fuel pump 9 is feedback-controlled based on the output signal value of the fuel pressure sensor 13 described above.

The fuel supplied from the fuel pump 9 to the common rail 7 is accumulated until the pressure of the fuel reaches a desired target pressure. The fuel accumulated in the common rail 7 up to the target pressure is distributed to the fuel injection valve 3 of each cylinder 2 via the fuel pipe 6. Each fuel injection valve 3 opens when a drive current is applied, and injects the fuel of the target pressure supplied from the common rail 7 into the combustion chamber of each cylinder 2.

In the above fuel system, the common rail 7
When the fuel pressure inside becomes higher than the maximum pressure, the pressure regulating valve 1
2 opens. In this case, a part of the fuel stored in the common rail 7 is returned to the fuel tank 8 via the return pipe 11, and the fuel pressure in the common rail 7 is reduced.

Next, the internal combustion engine 1 is connected to an intake branch pipe 14 formed so that four branch pipes merge into one collecting pipe. Each branch pipe of the intake branch pipe 14 communicates with the combustion chamber of each cylinder 2 via an intake port (not shown).
The collecting pipe of the intake branch pipe 14 is connected to the intake pipe 15,
The intake pipe 15 is connected to the air cleaner box 16.

At a portion of the intake pipe 15 immediately downstream of the air cleaner box 16, an air flow meter 17 for outputting an electric signal corresponding to the mass of intake air flowing in the intake pipe 15 and a flow in the intake pipe 15 are provided. An intake air temperature sensor 18 that outputs an electric signal corresponding to the intake air temperature is attached.

A variable nozzle type centrifugal supercharger (variable nozzle type turbocharger) which operates by using the thermal energy of the exhaust gas discharged from the internal combustion engine 1 as a drive source is provided at a portion of the intake pipe 15 downstream of the air flow meter 17. Nineteen compressor housings 19a are provided.

An intercooler 20 for cooling the intake air that has been compressed in the compressor housing 19a and has a high temperature is provided at a portion of the intake pipe 15 downstream of the compressor housing 19a.

An intake throttle valve 21 for adjusting the flow rate of intake air flowing through the intake pipe 15 is provided at a portion of the intake pipe 15 downstream of the intercooler 20.
The intake throttle valve 21 is provided with an intake throttle actuator 21a for opening and closing the intake throttle valve 21 and an intake throttle valve opening sensor 21b for outputting an electric signal according to the opening degree of the intake throttle valve 21. Has been.

In the intake system configured as described above, the intake air flowing into the air cleaner box 16 is cleaned by the air filter (not shown) in the air cleaner box 16 to remove dust and the like from the intake air, and then the intake pipe 15 Through the compressor housing 19 of the variable nozzle type centrifugal supercharger 19
flows into a.

The intake air flowing into the compressor housing 19a is compressed by the rotation of the compressor wheel installed in the compressor housing 19a. The intake air that has been compressed in the compressor housing 19a and has a high temperature is cooled by the intercooler 20.

The intake air cooled by the intercooler 20 is guided to the intake branch pipe 14 with its flow rate adjusted by the intake throttle valve 21 as necessary. The intake air introduced to the intake branch pipe 14 is distributed from the collecting pipe of the intake branch pipe 14 to each branch pipe and is introduced to the combustion chamber of each cylinder 2.

The intake air distributed to the combustion chamber of each cylinder 2 is compressed by a piston (not shown) and burned using the fuel injected from the fuel injection valve 3 as an ignition source.

Next, the internal combustion engine 1 is connected to an exhaust branch pipe 24 formed so that four branch pipes merge into one collecting pipe. Each branch pipe of the exhaust branch pipe 24 communicates with the combustion chamber of each cylinder 2 through an exhaust port (not shown).
The collecting pipe of the exhaust branch pipe 24 is connected to the exhaust pipe 25a via the turbine housing 19b of the variable nozzle type centrifugal supercharger 19.
It is connected to the.

A turbine wheel connected to the above-mentioned compressor wheel is rotatably mounted in the turbine housing 19b, and the turbine wheel is rotated by receiving the pressure of exhaust gas.

Further, the turbine housing 19b described above is used.
A nozzle vane that changes the cross-sectional area of the exhaust passage (nozzle passage) in the turbine housing 19b is installed inside. This nozzle vane is adapted to be opened and closed by a VNT actuator 19c.

The opening of the nozzle vane by the above-mentioned VNT actuator 19c (hereinafter referred to as the nozzle opening)
When the pressure is reduced, the cross-sectional area of the nozzle passage is reduced, so that the flow velocity and pressure of the exhaust gas flowing through the nozzle passage are increased, thereby increasing the rotation speed and the rotation torque of the turbine wheel.

On the other hand, the VNT actuator 19c
When the nozzle opening degree is increased by the above, the cross-sectional area of the nozzle passage is enlarged, so that the flow velocity and pressure of the exhaust gas flowing through the nozzle passage are reduced, and thus the rotational speed and the rotational torque of the turbine wheel are excessively increased. Suppressed.

Therefore, when the internal combustion engine 1 is in the low rotation speed operation state, in other words, when the flow velocity and pressure of the exhaust gas discharged from the internal combustion engine 1 are low, the rotational speed of the turbine wheel is reduced by reducing the nozzle opening. Also, it becomes possible to increase the rotation torque and thereby increase the intake supercharging pressure.

Further, when the internal combustion engine 1 is in a high rotation operation state, in other words, when the flow velocity and pressure of the exhaust gas discharged from the internal combustion engine 1 become high, the rotational speed of the turbine wheel is increased by increasing the nozzle opening. Also, it is possible to suppress an excessive increase in the rotation torque, and thus an excessive increase in the intake supercharging pressure.

The portion of the exhaust branch pipe 24 located immediately upstream of the turbine housing 19b and the exhaust pipe 2
5a is connected to a portion located immediately downstream of the turbine housing 19b by a turbine bypass passage 26 that bypasses the turbine housing 19b.

The turbine bypass passage 26 is provided with a wastegate valve 27 including a valve body 27a for opening and closing the turbine bypass passage 26 and an actuator 27b for driving the valve body 27a to open and close.

The actuator 27b is connected to the intake pipe 15 located immediately downstream of the compressor housing 19a via the operating pressure passage 28, and the pressure of the intake air flowing in the intake pipe 15 immediately downstream of the compressor housing 19a, in other words, the pressure of the intake air. For example, the valve body 27a is opened and closed by utilizing the pressure (supercharging pressure) of the intake air compressed in the compressor housing 19a.

Specifically, the actuator 27b
Closes the valve body 27a when the supercharging pressure of intake air is less than a preset predetermined pressure, and opens the valve body 27a when the supercharging pressure of intake air exceeds the predetermined pressure. Let

When the valve body 27a is opened, a part of the exhaust gas flowing through the exhaust branch pipe 24 flows into the exhaust pipe 25a through the turbine bypass passage 26, so the flow rate of the exhaust gas flowing into the turbine housing 19b. Is reduced and the pressure of the exhaust gas applied to the turbine wheel in the turbine housing 19b is reduced. As a result, the rotational energy transmitted from the turbine wheel to the compressor wheel is reduced, so that the supercharging pressure of the intake air is suppressed below the predetermined pressure.

Next, the exhaust pipe 25a is provided with a harmful gas component in the exhaust gas, particularly particulates such as soot (PM: Particulate Matte).
er) is connected to an exhaust gas purification mechanism 29. The exhaust purification mechanism 29 is connected to the exhaust pipe 25b, and the exhaust pipe 25b is connected downstream to a muffler (not shown). Below, the exhaust pipe 25 upstream of the exhaust purification mechanism 29
The a is referred to as an upstream exhaust pipe 25a, and the exhaust pipe 25b downstream from the exhaust purification mechanism 29 is referred to as a downstream exhaust pipe 25b.

The exhaust gas purification mechanism 29 is an embodiment of the trapping mechanism according to the present invention, and includes a DPF (Diesel Particulate Filter) for trapping PM contained in exhaust gas and a wall made of a porous base material. DPNR (Diesel Particulate NOx) in which an oxidation catalyst typified by platinum (Pt) and a NOx storage agent typified by potassium (K) or cesium (Cs) are carried on a flow type particulate filter.
Reduction) catalyst. In the following, the exhaust gas purification mechanism 29 will be referred to as the particulate filter 29.
Shall be called.

An exhaust gas temperature sensor 30 which outputs an electric signal corresponding to the temperature of the exhaust gas flowing through the upstream exhaust pipe 25a is attached to the upstream exhaust pipe 25a.

In the exhaust system configured as described above, the air-fuel mixture (burnt gas) burned in each cylinder 2 of the internal combustion engine 1 is discharged to the exhaust branch pipe 24 through the exhaust port of each cylinder 2,
Next, the exhaust branch pipes 24 flow into the turbine housing 19b of the variable nozzle centrifugal supercharger 19 through the collecting pipes.

The exhaust gas flowing into the turbine housing 19b rotates the turbine wheel. The rotation torque of the turbine wheel is determined by the compressor housing 1 described above.
9a, the compressor housing 19a acts as a drive source for compressing the intake air.

At this time, when the pressure (supercharging pressure) of the intake air compressed in the compressor housing 19a rises to a predetermined pressure or more, the actuator 27b of the wastegate valve 27 opens the valve body 27a, so the exhaust branch pipe. Part of the exhaust gas flowing through 24 flows to the upstream side exhaust pipe 25a via the turbine bypass passage 26, and an excessive increase in boost pressure is suppressed.

The exhaust gas discharged from the turbine housing 19b (and the exhaust gas passing through the turbine bypass passage 26) flows into the particulate filter 29 via the upstream side exhaust pipe 25a. Particulate filter 2
The exhaust gas that has flowed into the exhaust gas 9 is exhausted to the downstream exhaust pipe 25b after being purified or removed of soot particles contained in the exhaust gas, and is discharged into the atmosphere through the downstream exhaust pipe 25b.

Further, an exhaust gas recirculation passage (EGR passage) 100 is connected to the exhaust branch pipe 24, and the EGR passage 10
0 is connected to the intake branch pipe 14. The EGR
An EGR valve 101 that opens and closes an opening end of the EGR passage 100 in the intake branch pipe 14 is provided at a connection portion between the passage 100 and the intake branch pipe 14. The EGR
The valve 101 is composed of a solenoid valve or the like, and the opening degree can be changed according to the magnitude of applied power.

In the middle of the EGR passage 100, the EG
An EGR cooler 103 for cooling exhaust gas (hereinafter, referred to as EGR gas) flowing in the R passage 100 is provided.

Two pipes 104 and 105 are connected to the EGR cooler 103, and these two pipes 104 and 105 are connected to each other.
Reference numeral 105 is connected to a radiator 106 for radiating the heat of the cooling water of the internal combustion engine 1 to the atmosphere.

One of the two pipes 104 and 105 described above is a pipe for guiding a part of the cooling water cooled in the radiator 106 to the EGR cooler 103, and the other pipe. 105 is the E
It is a pipe for guiding the cooling water after circulating in the GR cooler 103 to the radiator 106. In the following, the pipe 104 will be referred to as a cooling water introduction pipe 104, and the pipe 1
05 is referred to as a cooling water outlet pipe 105.

An opening / closing valve 107 for opening and closing the flow path in the cooling water outlet pipe 105 is provided in the middle of the cooling water outlet pipe 105. The on-off valve 107 is composed of an electromagnetic drive valve that opens when drive power is applied.

The exhaust gas recirculation mechanism (E
(GR mechanism), when the EGR valve 101 is opened, EGR
The passage 100 becomes conductive, and a part of the exhaust gas flowing in the exhaust branch pipe 24 passes through the EGR passage 100 and the intake branch pipe 1
Guided to 4.

At this time, if the on-off valve 107 is in the open state, the circulation path connecting the radiator 106, the cooling water introducing pipe 104, the EGR cooler 103 and the cooling water outlet pipe 105 becomes conductive, and the radiator 106 cools. The cooling water circulates in the EGR cooler 103. as a result,
In the EGR cooler 103, heat exchange is performed between the EGR gas flowing in the EGR passage 100 and the cooling water circulating in the EGR cooler 103, and the EGR gas is cooled.

The EGR gas recirculated from the exhaust branch pipe 24 to the intake branch pipe 14 via the EGR passage 100 is supplied to the intake branch pipe 1
Each cylinder 2 while mixing with intake air flowing from upstream of 4
Of the fuel injection valve 3 and is burned with the fuel injected from the fuel injection valve 3 as an ignition source.

At this time, since the EGR gas contains an inert gas component such as water (H ₂ O) and carbon dioxide (CO ₂ ), such EGR gas is contained in the air-fuel mixture. As a result, the combustion temperature of the air-fuel mixture is lowered, and thus the amount of nitrogen oxide (NO _x ) generated is suppressed.

Further, in the EGR cooler 103, the EGR
When the gas is cooled, the temperature of the EGR gas itself is lowered and the volume of the EGR gas is reduced.
When the R gas is supplied into the combustion chamber, the ambient temperature in the combustion chamber does not unnecessarily rise, and the amount of intake air (intake volume) supplied into the combustion chamber does not unnecessarily decrease.

The internal combustion engine 1 thus constructed has an electronic control unit (EC) for controlling the internal combustion engine 1.
U: Electronic Control Unit) 31 is installed side by side. The ECU 31 is an arithmetic logic operation circuit that controls the operating state of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's request.

In addition to the crank position sensor 4, the water temperature sensor 5, the fuel pressure sensor 13, the air flow meter 17, the intake air temperature sensor 18, the intake throttle valve opening sensor 21b, and the exhaust gas temperature sensor 30, the ECU 31 includes the interior of the vehicle. The accelerator position sensor 33 or the like that outputs an electric signal corresponding to the operation amount (accelerator opening degree) of the accelerator pedal 32 provided in the vehicle is electrically connected, and the output signals of the above-described sensors are input to the ECU 31. Has become.

On the other hand, the ECU 31 includes a fuel injection valve 3, a fuel pump 9, a VNT actuator 19c, an intake throttle actuator 21a, an EGR valve 101, and an opening / closing valve 10.
7 and the like are electrically connected, and the above-mentioned respective parts are controlled by the ECU 31.

Here, as shown in FIG. 2, the ECU 31 is connected to the CP by the bidirectional bus 40.
U / 41 connected to the input port 45 while having a U41, a ROM 42, a RAM 43, a backup RAM 44, an input port 45, and an output port 46.
A D converter (A / D) 47 is provided.

The input port 45 inputs the output signals of a sensor that outputs a digital signal format signal such as the crank position sensor 4, and transmits those output signals to the CPU 41 and the RAM 43 via the bidirectional bus 40. To do.

The input port 45, like the water temperature sensor 5, the fuel pressure sensor 13, the air flow meter 17, the intake temperature sensor 18, the intake throttle valve opening sensor 21b, the exhaust temperature sensor 30, the accelerator position sensor 33, etc., is an analog port. The output signal of the sensor that outputs the signal of the signal format is A /
It is input via D47, and those output signals are transmitted to the CPU 41 and the RAM 43 via the bidirectional bus 40.

The output port 46 includes the fuel injection valve 3, the fuel pump 9, the VNT actuator 19c, the intake throttle actuator 21a, the EGR valve 101, and the opening / closing valve 10.
7 etc. electrically connected via a drive circuit not shown,
The control signal output from the CPU 41 is transmitted to each unit described above.

The ROM 42 stores a fuel injection control routine, an intake throttle control routine, an EGR control routine, a VN.
It stores various application programs such as the T control routine and various control maps.

The RAM 43 stores the output signal from each sensor, the calculation result of the CPU 41, and the like. The calculation result is, for example, the engine speed calculated based on the time interval at which the crank position sensor 4 outputs a pulse signal. These data are rewritten to the latest data each time the crank position sensor 4 outputs a pulse signal.

The backup RAM 44 is a non-volatile memory capable of storing data even after the operation of the internal combustion engine 1 is stopped.

The CPU 41 operates according to the application program stored in the ROM 42,
In addition to known control such as fuel injection control, intake throttle control, VNT control, and EGR control, PM trapping amount determination control of the particulate filter 29, which is the gist of the present invention, is executed.

The PM trapping amount determination control in this embodiment will be described below.

When PM is collected by the particulate filter 29, the exhaust passage in the particulate filter 29 is narrowed. Therefore, as shown in FIG. 3, as the amount of PM collected by the particulate filter 29 increases, the amount of particulate matter increases. The exhaust resistance in the curate filter 29 becomes high.

If the exhaust gas resistance in the particulate filter 29 becomes higher due to the increase in the amount of trapped PM, the back pressure acting on the internal combustion engine 1 rises, and the intake air amount of the internal combustion engine 1 decreases accordingly. Will be done.

Therefore, under the condition where the internal combustion engine 1 is in the same operating state, as shown in FIG. 4, the internal combustion engine 1 increases as the PM trapping amount of the particulate filter 29 increases.
Therefore, the intake air amount will be reduced.

As a result, it becomes possible to estimate the PM trapping amount of the particulate filter 29 using the intake air amount of the internal combustion engine 1 (output signal of the air flow meter 17) as a parameter.

By the way, the intake air amount of the internal combustion engine 1 is not limited to the PM trapping amount of the particulate filter 29.
The PM of the particulate filter 29 changes because it also changes depending on the opening of the intake throttle valve 21 and the opening of the EGR valve 101.
When estimating the collection amount, the opening degree of the intake throttle valve 21 and E
It is preferable to fix the opening degree of the GR valve 101 to be fully open.

Furthermore, the intake air amount of the internal combustion engine 1 also changes depending on the nozzle opening of the variable nozzle type centrifugal supercharger 19. This is because the supercharging pressure of the intake air changes and the back pressure acting on the internal combustion engine 1 changes according to the nozzle opening degree of the variable nozzle centrifugal supercharger 19.

On the other hand, the variable nozzle type centrifugal supercharger 19
A method of estimating the PM trapping amount of the particulate filter 29 after fixing the nozzle opening of No. 3 to fully closed or fully opened is conceivable.

In the present embodiment, the variable nozzle type centrifugal supercharger 19 is arranged upstream of the particulate filter 29. Therefore, the nozzle opening of the variable nozzle type centrifugal supercharger 19 is set under such a condition. Is fully closed, the exhaust pressure upstream of the variable nozzle centrifugal supercharger 19 increases, while the exhaust pressure downstream of the variable nozzle centrifugal supercharger 19 decreases. That is, when the opening degree of the nozzle of the variable nozzle type centrifugal supercharger 19 is fully closed, the pressure of the exhaust gas flowing into the particulate filter 29 decreases.

Here, the rise of the back pressure due to the amount of trapped PM in the particulate filter 29 becomes more remarkable as the pressure of the exhaust gas flowing into the particulate filter 29 becomes higher.

Therefore, when the pressure of the exhaust gas flowing into the particulate filter 29 decreases due to the nozzle opening of the variable nozzle centrifugal supercharger 19 being fully closed, the back pressure becomes difficult to rise and the intake air amount The amount of decrease tends to be small.

Further, the influence of the nozzle opening of the variable nozzle type centrifugal supercharger 19 on the intake air amount is larger on the open side than on the open side. Therefore, the actual nozzle opening when fully closed is controlled. When a situation in which the amount of soot changes every time due to the accumulation of soot or the like, it is difficult to establish the correlation between the amount of trapped PM and the amount of intake air.

In consideration of these circumstances, the particulate filter 2 is set with the intake air amount when the nozzle opening of the variable nozzle centrifugal supercharger 19 is fully closed as a parameter.
It can be said that the method of estimating the PM trapping amount of 9 is not appropriate.

Therefore, in the PM trapping amount determination control according to this embodiment, the CPU 41 controls the opening degree of the intake throttle valve 21, E
Opening degree of GR valve 101 and variable nozzle type centrifugal supercharger 19
After controlling the nozzle opening to be fully opened, the PM collection amount is estimated using the output signal of the air flow meter 17 as a parameter.

However, when the internal combustion engine 1 is in a normal operating state, the opening degree of the intake throttle valve 21, the opening degree of the EGR valve 101, and the nozzle opening degree of the variable nozzle type centrifugal supercharger 19 are fully opened. Then, the operating state and torque of the internal combustion engine 1 are changed carelessly, which leads to a decrease in drivability. Therefore, in the present embodiment, the intake throttle is conditioned on the condition that the internal combustion engine 1 is in the decelerating operating state. Opening of valve 21, EGR valve 10
The PM trapping amount is estimated by controlling the opening degree of 1 and the nozzle opening degree of the variable nozzle type centrifugal supercharger 19 to be fully opened.

The PM trapping amount determination control according to this embodiment will be specifically described below with reference to FIG.

FIG. 5 is a flow chart showing the PM trapping amount determination control routine. This PM trapping amount determination control routine is executed by the CPU 41 at predetermined time intervals (for example, every time the crank position sensor 4 outputs a pulse signal).
Is a routine that is repeatedly executed.

In the PM trapping amount determination control routine, the CPU
In S501, first, in S501, the engine rotation speed: Ne, the output signal value of the air flow meter 17 (intake air amount): Gn, the fuel injection amount: Q, the output signal value of the accelerator position sensor 33 (accelerator opening degree): Read Accp.

In S502, the CPU 41 causes the S50
Internal combustion engine 1 with the engine speed: Ne, fuel injection amount: Q, and accelerator opening: Accp read in 1 as parameters
Is in the deceleration operation state. For example, CP
In U41, the engine speed: Ne is a predetermined speed or more, the fuel injection amount: Q is “0”, and the accelerator opening degree: Accp
Is determined to be fully closed, it is determined that the internal combustion engine 1 is in the deceleration operation state.

When it is determined in S502 that the internal combustion engine 1 is not in the decelerating operation state, the CPU 41 once terminates the execution of this routine.

On the other hand, if it is determined in S502 that the internal combustion engine 1 is in the decelerating operation state, the CPU 41
Advances to S503. In S503, the CPU 41 controls the intake throttle actuator 21a, the EGR valve 101, and the VNT actuator 19c to fully open the intake throttle valve 21, the EGR valve 101, and the nozzle vane of the variable nozzle centrifugal supercharger 19.

In S504, the CPU 41 reads from the RAM 43 the latest engine speed: Ne and the output signal value of the air flow meter 17 (actual intake air amount): actual Gn.

In S505, the reference intake air amount control map stored in the ROM 42 in advance is accessed,
A reference intake air amount: Gnbase corresponding to the engine speed: Ne read in 504 is calculated.

According to the above reference intake air amount control map, PM is not trapped in the particulate filter 29, the internal combustion engine 1 is in the decelerating operation state, and the intake throttle valve 21
Is a full open state, the EGR valve 101 is a full open state, and the nozzle vane of the variable nozzle centrifugal supercharger 19 is a full open map showing the relationship between the engine speed and the intake air amount (reference intake air amount). Is.

In S506, the CPU 41 causes the S50
Reference intake air amount calculated in step 5: Gnbase to the above S50
Actual intake air amount read in step 4: Difference by subtracting actual Gn:
Calculate ΔGn.

In S507, the CPU 41 causes the difference:
ΔGn is the amount of PM trapped by the particulate filter 29: P
Convert to M. At that time, difference: △ Gn and PM collection amount: PM
It is also possible to experimentally obtain the relationship with and to map the relationship and store it in the ROM 42.

In S508, the CPU 41 causes the CPU 50 to execute the above S50.
PM collection amount calculated in 7: PM is determined whether it is equal to or more than a preset upper limit value of PM collection amount (PM collection amount upper limit value): PMmax.

When it is determined in S508 that the PM trapping amount: PM is less than the PM trapping amount upper limit value: PMmax, the CPU 41 does not need to regenerate the PM trapping ability of the particulate filter 29. Assumed, execution of this routine is once terminated.

On the other hand, when it is determined in S508 that the PM trapping amount: PM is equal to or more than the PM trapping amount upper limit value: PMmax, the CPU 41 needs to regenerate the PM trapping ability of the particulate filter 29. Therefore, PM reproduction processing is executed in S509.

In the PM regeneration process, the CPU 41 executes the exhaust gas temperature raising control in order to raise the exhaust gas temperature to a temperature range where PM can burn, for example. As a method of executing the exhaust gas temperature raising control, in addition to normal fuel injection (main fuel injection), each cylinder 2
Of unburned fuel by performing additional fuel injection (expansion stroke injection) during the expansion stroke of the cylinder, and performing additional fuel injection (exhaust stroke injection) during the exhaust stroke of each cylinder 2 in addition to the main fuel injection It is possible to exemplify a method of supplying to the filter 29 for combustion.

When the PM regeneration process is executed in this manner, the P collected in the particulate filter 29 is collected.
M burns and is removed from the particulate filter 29, and the PM trapping ability of the particulate filter 29 is regenerated.

When the CPU 41 executes the PM trapping amount determination control in this manner, the intake air amount when the intake vane valve 21, the EGR valve 101, and the nozzle vane of the variable nozzle type centrifugal supercharger 19 are fully opened is used as a parameter. Since the PM trapping amount of the particulate filter 29 is determined, the careless change of the intake air amount due to the nozzle opening of the variable nozzle type centrifugal supercharger 19 is prevented.
As a result, the intake air amount detected when determining the PM trapping amount of the particulate filter 29 becomes an amount that is correlated with the PM trapping amount of the particulate filter 29, and thus the PM trapping amount of the particulate filter 29. The collection amount can be accurately determined.

[0113]

According to the exhaust gas purification apparatus for an internal combustion engine according to the present invention, in an internal combustion engine provided with a collecting mechanism for collecting fine particles in exhaust gas and a variable nozzle type centrifugal supercharger, the intake of the internal combustion engine It becomes possible to accurately estimate the amount of trapped particulates in the trapping mechanism using the amount of air as a parameter.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an exhaust emission control device according to an embodiment is applied.

FIG. 2 is a block diagram showing the internal configuration of the ECU.

[Fig. 3] Exhaust resistance and P in the particulate filter
Diagram showing the relationship with the amount of M trapped

FIG. 4 is a diagram showing a relationship between a PM trapping amount of a particulate filter and an intake air amount of an internal combustion engine.

FIG. 5 is a flowchart showing a PM trapping amount determination control routine.

[Explanation of symbols]

1 ... Internal combustion engine 17 ... Air flow meter 19 ... Variable nozzle type centrifugal supercharger 19a ... Compressor housing 19b .. Turbine housing 19c ··· VNT actuator 21 ... Intake throttle valve 29 ... Particulate filter (collection mechanism) 31 ... ECU 41 ... CPU 101 ... EGR valve

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02B 37/24 F02D 9/02 315B 3G092 F02D 9/02 315 315K 3G301 21/08 301B 4D058 21/08 301 311B 311 41/12 360 41/12 360 360 43/00 301K 43/00 301 301N 301R 301T 45/00 314F 45/00 314 314Z F02M 25/07 570G F02M 25/07 570 570J 570P B01D 46/42 A // B01D 46 / 42 F02B 37/12 301Q (72) Inventor Kotaro Hayashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Naofumi Kumada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Shinobu Ishiyama 1 Toyota Town, Toyota City, Aichi Prefecture Inventor, Toyota Automobile Co., Ltd. (72) Daisuke Shibata 1 Toyota Town, Toyota City, Aichi Prefecture Inventor, Toyota Automobile Co., Ltd. (72) Takahiro Owa 1 Toyota Town, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Akihiko Negami 1 Toyota-cho, Toyota-shi, Aichi F-term inside Toyota Motor Co., Ltd. (reference) 3G005 EA15 EA16 FA35 GA04 GB25 GD03 HA12 HA19 JA12 JA13 JA16 JA39 JA42 JA45 3G062 AA01 BA02 BA04 BA05 BA06 CA05 ED08 GA01 GA04 GA06 GA08 GA09 GA12 3G065 AA01 AA03 AA04 CA12 DA04 DA15 EA05 EA10 FA14 GA05 GA08 GA09 GA10 GA27 GA41 GA46 HA06 HA21 HA22 JA04 JA09 JA11 KA02 BA05 BA08 BA15 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 BA08 EB22 FA07 FA10 FA20 FA27 FA33 FA38 3G090 AA03 CA01 DA01 DA09 DA11 DA12 DA14 DA18 DA20 EA05 EA06 EA07 3G092 AA02 AA06 AA13 AA17 AA18 AB03 AB20 BA01 BA04 BB01 BB10 DB03 DC03 DC09 DC14 DF01 DF02 DF06 EA01 EA02 FA18 FA36 FB06 GA13 GB08 HA01Y HA01Z HA07Y HA0 7Z HD01Y HD01Z HE02Y HE02Z HE03Y HE03Z HE08Y HE08Z HF09Y HF09Z 3G301 HA02 HA04 HA06 HA11 HA13 JA15 JA24 JB09 KA16 KA17 KA18 KB07 LA03 LB11 MA01 MA11 MA18 NE01 NE06 PA02B PA02Z PA12B PA12Z PA14B PA14Z PA17B PA17Z PD11B PD11Z PE02B PE02Z PE03B PE03Z PE08B PE08Z PF04B PF04Z 4D058 MA44 MA54 PA05 SA08

Claims (5)

[Claims] 1. A variable nozzle centrifugal supercharger provided in an intake passage and an exhaust passage of an internal combustion engine, and a collection mechanism provided in the exhaust passage of the internal combustion engine for collecting fine particles contained in exhaust gas. A control means for controlling the nozzle opening of the variable nozzle centrifugal supercharger to be fully opened when the internal combustion engine is in a deceleration operation state; and the variable nozzle centrifugal supercharger in which the internal combustion engine is in a deceleration operation state. Detecting means for detecting the intake air amount of the internal combustion engine when the nozzle opening of the container is fully opened, and estimating the particulate collection amount of the collection mechanism using the intake air amount detected by the detection means as a parameter An exhaust gas purifying apparatus for an internal combustion engine, comprising: an estimating unit. 2. An intake air throttle valve that is provided in an intake passage of the internal combustion engine and throttles a flow rate of air flowing through the intake passage, wherein the control means changes the variable when the internal combustion engine is in a deceleration operation state. The nozzle opening of the nozzle type centrifugal supercharger and the opening degree of the intake throttle valve are controlled to be fully opened, and the detection means is configured such that the internal combustion engine is in a decelerating operation state and the nozzle opening of the variable nozzle type centrifugal supercharger. Degree and the intake air amount of the internal combustion engine when the opening degree of the intake throttle valve is fully opened, the estimating means uses the intake air amount detected by the detecting means as a parameter, and the fine particles of the collecting mechanism. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein a trapped amount is estimated. 3. An EGR passage that recirculates a portion of the exhaust gas flowing through the exhaust passage of the internal combustion engine to an intake passage, and an EGR valve that adjusts the flow rate of the exhaust gas flowing through the EGR passage. When the internal combustion engine is in a decelerating operation state, the nozzle opening of the variable nozzle centrifugal supercharger and the opening degree of the EGR valve are controlled to be fully opened, and the detecting means sets the internal combustion engine to a decelerating operating state. And the nozzle opening of the variable nozzle centrifugal supercharger and the E
The amount of intake air of the internal combustion engine when the opening degree of the GR valve is fully opened is detected, and the estimation unit uses the amount of intake air detected by the detection unit as a parameter to determine the amount of particulate collection of the collection mechanism. The exhaust gas purification device for an internal combustion engine according to claim 1, which is estimated. 4. An intake throttle valve provided in an intake passage of the internal combustion engine for reducing a flow rate of air flowing through the intake passage, and an EGR passage for returning a part of exhaust gas flowing through the exhaust passage of the internal combustion engine to the intake passage. And an EGR valve that adjusts a flow rate of exhaust gas flowing through the EGR passage, and the control unit controls a nozzle opening degree of the variable nozzle centrifugal supercharger when the internal combustion engine is in a deceleration operation state. The opening degree of the intake throttle valve and the opening degree of the EGR valve are controlled to be fully opened, and the detection means is configured such that the internal combustion engine is in a deceleration operation state,
Further, the intake air amount of the internal combustion engine is detected when the nozzle opening of the variable nozzle centrifugal supercharger, the opening of the intake throttle valve, and the opening of the EGR valve are fully opened, and the estimating means is provided. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the particulate matter trapping amount of the trapping mechanism is estimated using the intake air amount detected by the detecting means as a parameter. 5. A determination means is further provided for determining that the trapping mechanism is clogged when the amount of intake air detected by the detection means falls below a predetermined amount. An exhaust emission control device for an internal combustion engine according to any one of claims 1 to 4.