JP2009257195A - Control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To favorably prevent a fire failure and a torque change from occurring when fuel of exhaust air is enriched, in a vehicle provided with an LPLEGR device. <P>SOLUTION: An ECU 100 of an engine system 10 provided with an LPLEGR 500 conducts LPLEGR control in a rich spike. In the above control, the rich spike is conducted by adding fuel by a fuel adding valve 220. The ECU 100 sets a target intake air volume Gatg so that the oxygen concentration of the intake air before and after the rich spike is conducted becomes steady based on an air-fuel ratio AFsens detected by an air-fuel ratio sensor 221. Once the target intake air volume Gatg is set, drive control of an LPLEGR valve 530 is started according to the target intake air volume Gatg when the control is started with taking the delay in motion of the LPLEGR valve 530 into consideration. At that time, the control starting time is calculated based on the cycle number of an engine 200. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technical field of a vehicle control device provided with an LPLEGR (Low Pressure Loop Exhaust Gas Recirculation) device.

  As a device to which this type of device can be applied, a device that prevents a torque drop during a rich spike has been proposed (see, for example, Patent Document 1). According to the exhaust gas purification apparatus for an internal combustion engine disclosed in Patent Document 1 (hereinafter referred to as “prior art”), the time until the recirculated exhaust gas reaches the recirculated exhaust gas amount adjustment control valve at the time of a rich spike is estimated. In addition, by adjusting the closing amount of the recirculated exhaust gas amount adjustment control valve in accordance with the estimated arrival time, it is possible to prevent misfire and torque reduction due to a decrease in oxygen concentration.

  A technique has also been proposed in which the oxygen concentration downstream of the filter is estimated based on the change in the filter soot accumulation amount and the EGR valve is controlled (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2001-234772 JP 2005-069207 A

  The flow rate and flow rate distribution of the EGR gas in the exhaust pipe (that is, the recirculated exhaust gas in the prior art) change according to the driving conditions of the vehicle and are not at least uniform. Therefore, the target value of the EGR rate that is the ratio of the EGR gas to the intake air (the gas sucked into the cylinder) is not uniform at the time of such a rich spike. However, in the prior art, there is no description about how to set the EGR rate, and it is only expressed that the closing amount of the recirculated exhaust gas amount adjustment control valve is adjusted. For this reason, in the conventional technology, when the arrival time of the EGR gas is taken into consideration, the oxygen concentration in the intake air changes to the oxygen-deficient side due to inert CO 2 or the like contained in the EGR gas at the time of the rich spike, and the combustion chamber However, it is not necessarily possible to eliminate the possibility of a rich misfire that occurs due to the relative fuel-rich state and a lack of torque due to a decrease in combustion performance. That is, the conventional technique has a technical problem that misfire, insufficient torque, or the like may occur when the exhaust gas is enriched by, for example, a rich spike.

  The present invention has been made in view of the above-described problems, and provides a vehicle control device capable of suitably preventing misfire and torque change when exhaust fuel enrichment is achieved. Let it be an issue.

  In order to solve the above-described problems, a vehicle control apparatus according to the present invention includes an internal combustion engine, an exhaust gas purification unit configured to purify exhaust gas of the internal combustion engine and including at least a NOx storage catalyst, and the exhaust gas. And a flow control valve at a branch position set on the downstream side of the exhaust gas purification means, the flow rate according to the open / close state of the flow control valve. LPLEGR device capable of recirculating a part of the exhaust gas as LPLEGR gas to the intake system of the internal combustion engine, and corresponding to the air-fuel ratio of the exhaust gas downstream of the exhaust gas purifying means and upstream of the branch position And a detection unit capable of detecting a physical quantity to be detected when the predetermined execution condition is satisfied so that the exhaust is enriched in fuel. Intake air so that the oxygen concentration in the intake air sucked into the cylinder of the internal combustion engine is constant before and after the exhaust gas is fuel-rich based on the detected physical quantity. A setting means for setting a target intake air amount that is a target value of the amount; a specifying means for specifying an arrival time as a time when the fuel-rich exhaust reaches the flow control valve; and at the specified arrival time, And a second control means for controlling the flow rate control valve in consideration of a response delay of the flow rate control valve so that the intake air amount becomes the set target intake air amount.

  The “internal combustion engine” according to the present invention has one or a plurality of cylinders, and in a combustion chamber in each of the cylinders, for example, a fuel such as gasoline, light oil or various alcohols, or an explosion of an air-fuel mixture containing the fuel or This is a concept encompassing an engine configured to be able to take out the force generated by combustion as a driving force through a physical or mechanical transmission path such as a piston, a connecting rod and a crankshaft, for example, 2 Cycle or 4-cycle reciprocating engine. In a preferred embodiment, the internal combustion engine according to the present invention uses light oil as fuel, and injects the fuel in the process of compressing the intake air (for example, at the compression end). Compressed self-ignition internal combustion such as a diesel engine, which generates combustion by self-ignition, or generates combustion by self-ignition in a high-temperature and high-pressure cylinder in a process in which a mixture of intake air and fuel is compressed in the cylinder Configured as an institution.

  The internal combustion engine according to the present invention includes, for example, an exhaust purification means including at least a catalyst capable of storing NOx, such as an NSR (NOx storage reduction) catalyst or a DPF (Diesel Particulate Filter) supporting a NOx storage layer. Is provided. When this type of catalyst is provided, it is necessary to appropriately regenerate the catalyst by oxidizing and burning NOx stored at a constant or indefinite timing. At this time, the exhaust gas is enriched (ie, reduced to the air-fuel ratio corresponding to the reference state in terms of the air-fuel ratio) by the enrichment means capable of enriching the exhaust gas with respect to the reference state. . The exhaust gas enriched with fuel is caused by, for example, surplus fuel components combusted in the exhaust pipe to raise the temperature of the exhaust gas purification means. Inside the exhaust gas purification means, HC as unburned fuel, CO as burned gas, etc. The reduction reaction of NOx proceeds.

  The “riching means” according to the present invention is not limited in its configuration (in particular, physical, mechanical, electrical, or magnetic configuration) as long as the exhaust can be enriched with fuel. . For example, the enrichment means may be an exhaust pipe, for example, an exhaust addition valve capable of adding fuel to the exhaust in a portion near the exhaust manifold, etc. as a preferred embodiment. Alternatively, in view of the fact that exhaust gas can inevitably become fuel-rich if oxygen is insufficient in the combustion chamber, the enrichment means refers to various injection means (for example, injectors) that can inject fuel, or intake air. Various throttle valves (for example, a throttle valve or the like) that can throttle the supply amount (that is, the intake air amount) may be appropriately included.

  On the other hand, in the internal combustion engine according to the present invention, the downstream side of the exhaust purification means (note that the “downstream side” is a directional concept based on the direction in which the exhaust flows, that is, the side away from the cylinder). Is provided with an LPLEGR device that recirculates a part of the exhaust gas as LPLEGR gas to the intake system through a flow rate control valve whose opening and closing state is variable in a binary, stepwise, or continuously manner from the branch position set in (1). That is, the internal combustion engine according to the present invention may be provided with a turbocharger or the like as a preferred embodiment, and the exhaust gas is supplied with, for example, rotational energy to the turbine and then the turbocharger such as a compressor. It is recirculated as LPLEGR gas to the upstream side (here, the direction concept based on the flow of intake air, the side away from the cylinder), that is, the low pressure side.

The LPLEGR device qualitatively includes, for example, an exhaust system that can appropriately include an exhaust port, an exhaust manifold, an exhaust pipe (including those that occur in the cylinder arrangement such as a front pipe and a rear pipe), and the like. As an EGR gas containing a large amount of inert CO ₂ , for example, an intake system as a concept that can appropriately include an intake port, an intake manifold, an intake pipe, etc., directly or indirectly, or an EGR valve, etc. It is a kind of so-called EGR device that can be circulated and supplied in a limited manner according to the state of a valve body, valve mechanism, valve device, valve system or similar mechanism that can control the amount of gas circulation. The internal combustion engine according to the present invention may include an HPL (High Pressure Loop) EGR device in addition to this type of LPLEGR.

  According to the vehicle control device of the present invention, the first control unit can take various forms such as various processing units such as an ECU (Electronic Control Unit), various controllers, various computer systems such as a microcomputer device, and the like. For example, the control means preferably satisfies a condition that the NOx occluded in the exhaust purification means should be reduced (for example, when the NOx occlusion amount exceeds or is estimated to exceed the reference value). The enrichment means is controlled so that the exhaust is enriched with fuel when a predetermined execution condition included as a form is satisfied.

  Here, when the exhaust gas is enriched, a large amount of inactive CO2 is generated by the NOx reduction reaction in the exhaust gas purification means, particularly in the NOx storage reduction catalyst, and the LPLEGR gas containing a large amount of CO2 is taken into the intake air. Reflux to system. Also, particularly when reducing NOx, a relatively large amount of reducing agent is required and not all of the reducing agent is used in the reduction reaction. However, a part of the fuel can be dry-distilled as LPLEGR gas in the intake system while maintaining the fuel-rich state. For this reason, intake air (that is, a mixture of at least intake air and this LPLEGR gas in a situation where the LPLEGR gas is recirculated considerably in consideration of the total amount of gas sucked into the cylinder) The oxygen concentration is reduced, whether absolute or relative. For this reason, misfire (rich misfire) or lack of torque may occur in the combustion chamber due to lack of oxygen.

  Here, in particular, in order to make up for such a shortage of oxygen concentration, even if the flow control valve is controlled to the valve closing side without any guidance (for example, in an extreme case, this kind of fuel enrichment) (Including the control of prohibiting the recirculation of LPLEGR gas by fully closing the flow rate control valve in the case of the occurrence of an oxygen concentration), and the lack of oxygen concentration can be prevented. There is substantially no change, and there is a high possibility that other problems such as misfire or torque reduction, or deterioration of the combustion state due to a decrease in the combustion temperature, occurrence of knocking, etc. will become apparent. In other words, when the exhaust is enriched with fuel, it is necessary to optimize the intake air amount (or LPLEGR amount) so that this type of problem does not occur.

  However, no matter what the fuel enrichment of the exhaust gas is made, the fuel flowing through the exhaust pipe is produced particularly when a transient and relatively large fuel rich state for the purpose of NOx reduction is created. The rich exhaust state is unstable, and the LPLEGR device has any temporal pattern or spatial pattern of fuel-rich exhaust (in other words, the pattern is a concept corresponding to density or flow rate. The control amount at the start of fuel enrichment (for example, the amount of fuel added) is substantially different from whether it is possible to adapt in advance or not. Is equal to not knowing. For this reason, in practice, the combustion state of the internal combustion engine that correlates with the occurrence of misfire or torque reduction is likely to change before and after this type of fuel enrichment.

  Therefore, according to the vehicle control apparatus of the present invention, during the operation, the physical quantity corresponding to the air-fuel ratio of the exhaust gas is provided on the downstream side of the exhaust purification unit and the upstream side of the above-described branch position of the LPLEGR device (note that “air-fuel ratio” "Physical quantity corresponding to" means that the air-fuel ratio itself is included, and the air-fuel ratio can be estimated or derived directly or indirectly, including a physical quantity such as oxygen concentration). The first control means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device based on various physical quantities detected by a detection means such as an air-fuel ratio sensor, The target intake air amount that is the target value of the intake air amount is set so that the oxygen concentration in the intake air is constant before and after the fuel is enriched.

  Here, such a target intake air amount can be detected by, for example, an intake air amount that can be defined by the pressure of the intake manifold (hereinafter referred to as “inmani pressure” as appropriate), the engine rotational speed, etc. It is also possible to set as a result of numerical calculation processing based on the intake air amount at the time, the fuel injection amount in the internal combustion engine, the exhaust air-fuel ratio, etc. It can also be set by referring to it. That is, as long as the oxygen concentration before and after fuel enrichment is set to be constant, the target intake air amount setting mode is not limited in any way. Note that “being constant” does not only mean that it is strictly constant as a result, but it is almost equal in a range in which a change in the combustion state to the extent that it becomes manifest as some trouble in practice does not occur. It is a concept that includes things.

  In addition, supplementally, various controls related to fuel enrichment, whether instantaneously, transiently, or performed over a relatively long period of time, have a finite execution period on the time axis. Have. Therefore, according to the detection period of the detection means, the physical quantity detected by the detection means is not necessarily a single value, but preferably a plurality of values that are contiguous on the time axis. The plurality of values can be index values that define the spatial pattern of the fuel-rich exhaust that propagates in the exhaust pipe described above. For this reason, the target intake air amount is preferably stored temporarily or permanently in a form associated with the time information in accordance with the spatial pattern of the exhaust gas that changes every moment.

  On the other hand, according to the vehicle control apparatus of the present invention, the fuel enriched by the specific means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device during operation. Exhaust reaches the flow control valve (Note that, in view of the fact that it is appropriately subjected to a reduction reaction in the exhaust gas purification means, it does not necessarily reach the original state of fuel enrichment. The arrival time as a time is specified. Since the detection means described above is provided on the upstream side of the flow control valve, the above-described physical quantity of the fuel-rich exhaust gas is detected, and the time when the above-described target intake air amount is set is ideally the fuel-rich condition. It is before the time when the exhausted exhaust reaches the flow control valve.

  For this reason, according to the vehicle control device of the present invention, the second control means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device, for example, at a specified arrival time. It is possible to control the flow rate control valve so that the intake air amount becomes the set target intake air amount. At this time, as a preferred embodiment, the control of the flow control valve is also performed on the time axis in accordance with the detection of the physical quantity that changes every moment at the installation position of the detection means and the target intake air amount that is sequentially set based on the detection. In a finite range, it is variably executed stepwise or continuously.

  Further, the second control means may have an inherent property depending on the configuration of the flow control valve, whether the flow control valve is directly opened / closed or indirectly opened / closed via an appropriate drive device. Consider physical, mechanical, electrical, or magnetic response delays. That is, from a practical point of view, the time when the flow control valve is instructed to be opened / closed according to the propagation mode of the exhaust gas enriched with fuel is the fuel-rich state where the flow control valve actually starts opening / closing. It is earlier in time series than the arrival time of the converted exhaust gas.

  As described above, according to the vehicle control apparatus of the present invention, the oxygen concentration of the intake air before and after the execution of the fuel enrichment of the exhaust gas according to the physical quantity corresponding to the air-fuel ratio actually detected on the downstream side of the exhaust gas purification unit. Is set to be constant, and is used for opening / closing control of the flow rate control valve in the LPLEGR device. For this reason, the oxygen concentration of the intake air before and after the execution of the fuel enrichment is accurately set within a desired deviation (preferably zero, that is, the oxygen concentration of the intake air is strictly matched before and after the execution of the fuel enrichment). It becomes possible. In other words, it becomes possible to optimize the amount of intake air at the time of fuel enrichment. For example, the exhaust gas enrichment of the exhaust, which is originally performed in a dimension different from the requirements related to vehicle travel, such as NOx purification, can cause misfire and torque. A situation that causes various problems such as changes is suitably prevented.

  In one aspect of the vehicle control apparatus according to the present invention, the specifying means specifies the arrival time based on the number of cycles of the internal combustion engine.

  According to this aspect, the specifying unit specifies the arrival time of the exhaust gas enriched based on the number of cycles of the internal combustion engine to the flow control valve. According to the applicant of the present application, the time at which the enriched exhaust gas reaches the flow rate control valve varies depending on the mode of enrichment. Was also found to depend on the number of cycles of the internal combustion engine. Of course, the number of cycles per short time changes depending on the engine speed, so there is of course a correlation with the engine speed and it is possible to conceptualize the number of cycles based on the engine speed. However, simply associating the engine speed with the time value required to reach it does not make much sense in practice, and there is a significant difference in its effect. That is, when the arrival time is specified based on the concept of the number of cycles, it is possible to easily specify the arrival time easily, and the oxygen concentration in the intake air is more accurately maintained before and after fuel enrichment of the exhaust gas. It becomes possible to do.

  In another aspect of the vehicle control device according to the present invention, the vehicle control device further includes a determination unit that determines whether the specified arrival time precedes the control start time of the flow control valve, and the setting unit includes When it is determined that the specified arrival time is ahead of the control start time of the flow control valve, the target intake is performed based on the estimated physical quantity that is the physical quantity corresponding to the exhaust after fuel enrichment set in advance. An air amount is set, and the second control means controls the flow control valve so that the intake air amount becomes a target intake air amount set based on the estimated physical quantity at the specified arrival time.

  For example, in the high rotation region, the number of cycles per unit time increases as described above, so that the time required for a predetermined cycle to pass decreases. For this reason, if the target intake air amount is set after the detection means detects the physical quantity corresponding to the air-fuel ratio, the above-described opening / closing control of the flow control valve in consideration of the response delay may not be in time.

  According to this aspect, for example, whether the specified arrival time precedes the control start time of the flow control valve by the discriminating means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. If the flow rate control valve control based on the actual measurement value of the detection means is not in time as described above, the target intake air amount is set based on the preset estimated physical quantity. At this time, the second control means controls the intake air amount to the target intake air amount based on the estimated physical quantity, so that the oxygen concentration in the intake air before and after the fuel enrichment of the exhaust gas is maintained as much as possible. And torque fluctuations are suppressed as much as possible.

  In this aspect, the estimated physical quantity may further include a first correction unit that corrects the estimated physical quantity according to the engine speed of the internal combustion engine.

  In this case, the estimated physical quantity is corrected according to the engine rotational speed by the first correcting means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. For this reason, the estimated physical quantity is obtained more accurately, and the occurrence of misfire and torque fluctuation is more suitably suppressed.

  In another aspect of the control device for an internal combustion engine according to the present invention, the setting means is based on the base intake air amount as the intake air amount and the detected physical amount when it is assumed that the exhaust is not enriched. When the target intake air amount is set and a change occurs in the base intake air amount, further comprising second correction means for correcting the target intake air amount according to the change amount related to the change. 2 The control means controls the flow rate control valve so that the intake air amount becomes the corrected target intake air amount.

  According to this aspect, for example, the base pedal is operated by operating the accelerator pedal or the like at an arbitrary time in the period from when the target intake air amount is set until the fuel-rich exhaust reaches the flow control valve. When the intake air amount changes, the second correction means that can take the form of various processing units such as ECUs, various controllers or various computer systems such as a microcomputer device, and the like according to the change amount of the base intake air amount. The intake air amount is corrected.

  For this reason, it is possible to prevent a situation in which the target intake air amount deviates from the optimum value due to a change in the base intake air amount, resulting in a change in the combustion performance, and the practice of optimizing the intake air amount to obtain a suitable combustion performance. The above benefits can be enjoyed more widely.

  In this aspect, when the control of the flow rate control valve in accordance with the set target intake air amount is started, the second correction unit performs the operation according to the base intake air amount at the present time. The target intake air amount may be corrected.

  As described above, even when the base intake air amount has changed in the period after the optimization of the intake air amount by the opening / closing drive of the flow control valve has already started, the target intake air amount depends on the current base intake air amount. By correcting the amount of air, it is possible to suppress as much as possible the change in combustion performance when the fuel is enriched in exhaust gas.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

<Embodiment of the Invention>
Various preferred embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>
<Configuration of Embodiment>
First, the configuration of the engine system 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram conceptually showing the configuration of the engine system 10.

  In FIG. 1, an engine system 10 is mounted on a vehicle (not shown) and includes an ECU 100, an engine 200, an HPLEGR 300, a DPNR (Diesel Particulate NOx Reduction system) 400, and an LPLEGR 500.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the entire operation of the engine 200. This is an example of a “vehicle control device”. The ECU 100 is configured to execute rich spike time LPLEGR control, which will be described later, in accordance with a control program stored in the ROM.

  The ECU 100 functions as an example of each of the “first control unit”, “setting unit”, “specifying unit”, “second control unit”, “determination unit”, and “first correction unit” according to the present invention. The electronic control unit is configured as described above, and all the operations related to these means are configured to be executed by the ECU 100. However, the physical, mechanical, and electrical configurations of each of the units according to the present invention are not limited to this. For example, each of these units includes a plurality of ECUs, various processing units, various controllers, a microcomputer device, and the like. It may be configured as various computer systems.

  The engine 200 is an in-line four-cylinder diesel engine that is an example of an “internal combustion engine” according to the present invention that uses light oil as fuel. The outline of the engine 200 will be described. The engine 200 has a configuration in which four cylinders 202 are arranged in parallel in a cylinder block 201. The force generated when the air-fuel mixture containing the fuel is compressed and ignited in each cylinder causes a piston (not shown) to reciprocate in a direction perpendicular to the paper surface, and is further connected to the piston via a connecting rod. It is configured to be converted into a rotational motion (both not shown). Below, the principal part structure of the engine 200 is demonstrated with a part of the operation | movement. The engine 200 according to this embodiment is an in-line four-cylinder diesel engine in which four cylinders 202 are arranged in parallel in a direction perpendicular to the paper surface in FIG. 1, but the configuration of the individual cylinders 202 is equal to each other. Here, only one cylinder 202 will be described.

  During combustion of the air-fuel mixture in the cylinder 202, the intake air, which is the air sucked from the outside through the air filter, is guided to the intake pipe 203. A diesel throttle valve 204 capable of adjusting the amount of intake air is disposed in the intake pipe 203. The diesel throttle valve 204 is a rotary valve that is configured to be rotatable by a driving force supplied from a throttle valve motor (not shown) that is electrically connected to the ECU 100 and controlled by the ECU 100 in a higher level. The rotational position is continuously controlled from the fully closed position where the upstream portion and the downstream portion of the intake pipe 203 at the boundary of 204 are substantially blocked to the fully opened position where the intake pipe 203 communicates almost entirely.

  The engine 200 is a diesel engine, and its output is controlled through injection amount increase / decrease control, unlike air-fuel ratio control (control according to the intake air amount) in an engine using gasoline or the like as fuel. Therefore, the diesel throttle valve 204 is basically controlled to the fully open position (the position of the illustrated diesel throttle valve 204 corresponds to the fully open position) during the operation period of the engine 200.

  The intake pipe 203 is connected to the intake manifold 206 on the downstream side of the diesel throttle valve 204 and communicates with the inside thereof. The intake manifold 206 is provided with an intake manifold pressure sensor 205 that can detect the intake manifold pressure Pin, which is the pressure inside the intake manifold 206. The intake manifold pressure sensor 205 is electrically connected to the ECU 100, and the detected intake manifold pressure Pin is referred to by the ECU 100 at a constant or indefinite period. The intake manifold 206 further communicates with an intake port 207 provided in each cylinder.

  The intake air guided to the intake pipe 203 is mixed with HPLEGR gas, which will be described later, at a merging position near the inlet of the intake manifold 206, and intake air (not shown) configured to allow the intake port 207 and the inside of the cylinder to communicate with each other. When the valve is opened, it is sucked into the cylinder 202 as intake air. In the cylinder 202, light oil as fuel is injected from a cylinder direct injection type unit injector 208, and the injected fuel is mixed with the intake air inside each cylinder, Become.

  Although not described in detail, the fuel is stored in a fuel tank (not shown). The fuel stored in the fuel tank is pumped out of the fuel tank by the action of a feed pump (not shown), and can take various known modes via a low-pressure pipe (not shown) and is pumped to a high-pressure pump (not shown). It has a configuration. This high-pressure pump is configured to be able to supply fuel to the common rail 209.

  The common rail 209 is electrically connected to the ECU 100, and is configured to store high pressure fuel supplied from the upstream side (that is, the high pressure pump side) up to a target rail pressure set by the ECU 100. It is. The common rail 209 is provided with a rail pressure sensor capable of detecting the rail pressure and a pressure limiter for limiting the amount of fuel accumulated so that the rail pressure does not exceed the upper limit value. The illustration is omitted. The unit injector 208 described above is mounted for each cylinder 202, and each unit injector 208 is connected to the common rail 209 via the high-pressure delivery 210.

  Here, to supplement the configuration of the unit injector 208, the unit injector 208 includes a solenoid valve that operates based on a command supplied from the ECU 100, and a nozzle that injects fuel when the solenoid valve is energized (both not shown). With. The solenoid valve is configured to be able to control the communication state between the pressure chamber to which the high pressure fuel of the common rail 209 is applied and the low pressure side low pressure passage connected to the pressure chamber. The pressurizing chamber and the low pressure passage are communicated with each other, and the pressurizing chamber and the low pressure passage are shut off from each other when energization is stopped.

  On the other hand, the nozzle has a built-in needle for opening and closing the nozzle hole, and the fuel pressure in the pressure chamber urges the needle in the valve closing direction (direction in which the nozzle hole is closed). Accordingly, when the pressure chamber and the low-pressure passage are connected by energization of the solenoid valve and the fuel pressure in the pressure chamber decreases, the needle rises in the nozzle and opens (opens the nozzle hole), thereby causing the common rail 209 to open. The high-pressure fuel supplied more can be injected from the injection hole. In addition, when the energization of the solenoid valve is stopped, the pressurization chamber and the low pressure passage are cut off from each other and the fuel pressure in the pressure chamber rises, and the needle is lowered in the nozzle to close the valve, thereby terminating the injection. It has become.

  The fuel corresponding to the target injection amount in each cylinder 202 is passed through the unit injector 208 to prevent a rapid temperature rise in the combustion chamber or to sufficiently premix the fuel and the intake air. Therefore, the fuel injection is divided into main injection corresponding to the difference between the target injection amount and the pilot injection amount.

  The above-mentioned air-fuel mixture burns by self-ignition in the compression stroke, and opens an exhaust valve (not shown) that opens and closes in conjunction with opening and closing of the intake valve as a burned gas or a partially unburned air-fuel mixture The structure is sometimes led to the exhaust manifold 212 via the exhaust port 211. The exhaust manifold 212 communicates with the exhaust pipe 213, and most of the exhaust gas is guided to the exhaust pipe 213.

  On the other hand, a turbine 215 is installed in the exhaust pipe 213 so as to be accommodated in the turbine housing 214. The turbine 215 is configured to be rotatable about a predetermined rotation axis by the pressure of exhaust gas (that is, exhaust pressure) guided to the exhaust pipe 213. The rotating shaft of the turbine 215 is shared with the compressor 216 installed in the intake pipe 203 so as to be accommodated in the compressor housing 217. When the turbine 215 is rotated by exhaust pressure, the compressor 216 is also centered on the rotating shaft. It is configured to rotate.

  The compressor 216 is configured to be able to pump and supply the intake air guided to the intake pipe 203 to the above-described intake manifold 206 by the pressure associated with the rotation thereof. Supercharging is realized. In other words, the turbine 215 and the compressor 216 constitute a kind of turbocharger. Further, an intercooler 219 is installed between the compressor 216 and the intake manifold 206, and the supercharging efficiency is improved by cooling the supercharged intake air.

  An air flow meter 218 capable of detecting an intake air amount Ga, which is the amount of intake air, is disposed on the upstream side of the compressor 216 in the intake pipe 203. The air flow meter 218 is electrically connected to the ECU 100, and the detected intake air amount Ga is referred to by the ECU 100 at a constant or indefinite period. Note that an LPLEGR passage 510 for introducing LPLEGR gas, which will be described later, is connected between the air flow meter 218 and the compressor 216 in the intake pipe 203, and is configured to communicate with the intake pipe 203 therein. That is, the intake air sucked into the cylinder 202 is a mixture of intake air, LPLEGR gas, and HPL gas as appropriate (mixing ratios vary widely).

  The HPLEGR 300 is an exhaust gas recirculation device configured to be able to recirculate a part of exhaust gas to the intake system, and includes an HPLEGR passage 310, an HPLEGR cooler 320, and an HPLEGR valve 330.

  The HPLEGR passage 310 is a metallic and hollow tubular member that branches from the exhaust manifold 212 and communicates the exhaust manifold 212 and the intake pipe 203. The HPLEGR passage 310 communicates with the intake pipe 203 at the merging position upstream of the intake manifold 206 described above. It has a configuration. The exhaust gas guided to the HPLEGR passage 310 is recirculated to the joining position as HPLEGR gas.

  The HPLEGR cooler 320 is a cooling device provided in the HPLEGR passage 310. The HPLEGR cooler 222 is a metal and hollow tubular member with the cooling water piping of the engine 200 stretched around the outer periphery, and the HPLEGR gas guided to the HPLEGR passage 310 is cooled by heat exchange with the cooling water, The structure is such that it is guided to the downstream side (that is, the intake pipe 203 side). The HPLEGR cooler 320 is connected to an inlet pipe and an outlet pipe, each of which communicates with the water jacket described above. At this time, the cooling water flows into the cooling water pipe from the inlet pipe and is discharged out of the cooling water pipe through the outlet pipe. The discharged cooling water is returned to the cooling water circulation system of the engine 200, and is supplied again from the inlet pipe through a predetermined path.

  The HPLEGR valve 330 is a valve mechanism including an openable and closable valve body installed in the HPLEGR passage 310 on the downstream side of the HPLEGR cooler 320 and a driving device that drives the valve body. The valve body of the HPLEGR valve 330 is configured such that the open / close state is continuously changed by the driving device, and the flow rate of the HPLEGR gas flowing through the HPLEGR passage 310, that is, the HPLEGR amount is controlled according to the open / close state. It is configured to be able to. The driving device of the HPLEGR valve 330 is electrically connected to the ECU 100, and the opening / closing state of the valve body of the HPLEGR valve 330 is controlled by the ECU 100 to the upper level.

  In the present embodiment, it is assumed that the HPLEGR 300 is not operating for the purpose of preventing the explanation from becoming complicated.

  A fuel addition valve 220 is installed in the exhaust manifold 212. The fuel addition valve 220 is an injector that is driven by a drive system (not shown) and configured to inject fuel into the exhaust manifold 212. The fuel addition valve 220 is an example of the “riching means” according to the present invention. The drive system of the fuel addition valve 220 is electrically connected to the ECU 100 and is configured to be controlled higher by the ECU 100.

  The DPNR 400 is an example of the “exhaust purification unit” according to the present invention, in which a CCO (oxidation catalyst) 410, a DPF (Diesel Particulate Filter) 420, and an NSR catalyst 430 are arranged in parallel in the exhaust flow direction.

  The CCO 410 is a catalyst configured such that a noble metal such as platinum is supported on a porous basic carrier such as alumina, and is capable of oxidizing CO, HC (mainly SOF), NO and the like in exhaust gas.

  The DPF 420 is a filter configured to capture PM (Particulate Matter) in the exhaust gas. The DPF 420 has a structure in which a filter made of a ceramic carrier such as cordierite or SiC is accommodated in a metal casing. This filter has a plurality of exhaust passages extending in the direction of exhaust flow and having a cross section perpendicular to the direction of exhaust flow forming a honeycomb shape. The exhaust passages are alternately sealed so that one of the inlet side and the outlet side of the exhaust is not adjacent to each other, and the DPF 420 has a so-called ceramic wall flow type filter structure.

The NSR catalyst 430 is a NOx occlusion reduction catalyst in which a NOx occlusion material such as alkali metal or alkaline earth metal and a noble metal are supported on a porous carrier such as alumina. The NSR catalyst 430 oxidizes NO in exhaust gas into NOx on a noble metal in a lean atmosphere, and the NOx occlusion material, which is a basic substance, neutralizes and reacts with NOx to form nitrates and nitrites to occlude NOx. In the fuel-rich atmosphere, the stored nitrate and nitrite decompose and NOx is released, and it reacts with reducing agents such as HC and CO by the catalytic action of precious metals. Thus, the structure is purified to N ₂ .

  The LPLEGR 500 is an exhaust gas recirculation device configured to be able to recirculate a part of exhaust gas to the intake system, and is an example of the “LPLEGR device” according to the present invention. The LPLEGR 500 includes an LPLEGR passage 510, an LPLEGR cooler 520, and an LPLEGR valve 530.

  The LPLEGR passage 510 is a metal and hollow tubular member branched from the exhaust pipe 213 at the LPL branch position downstream of the DPNR 400, and is configured to communicate with the intake pipe 203 described above at the LPL merge position provided upstream of the compressor 216. It has become. The exhaust gas led to the LPLEGR passage 510 is recirculated to the LPL merge position as LPLEGR gas.

  The LPLEGR cooler 520 is a cooling device provided in the LPLEGR passage 510. The LPLEGR cooler 222 is a metal and hollow tubular member with the cooling water piping of the engine 200 stretched around the outer periphery, and the HPLEGR gas guided to the LPLEGR passage 510 is cooled by heat exchange with the cooling water, The structure is such that it is guided to the downstream side (that is, the intake pipe 203 side). The LPLEGR cooler 520 is connected to an inlet pipe and an outlet pipe that communicate with the water jacket described above. At this time, the cooling water flows into the cooling water pipe from the inlet pipe and is discharged out of the cooling water pipe through the outlet pipe. The discharged cooling water is returned to the cooling water circulation system of the engine 200, and is supplied again from the inlet pipe through a predetermined path.

  The LPLEGR valve 530 is a valve mechanism that includes an openable and closable valve element installed in the LPLEGR passage 510 on the downstream side of the LPLEGR cooler 520 and a drive device that drives the valve element. The valve body of the LPLEGR valve 530 is configured so that the open / close state is continuously changed by the driving device, and the flow rate of the LPLEGR gas flowing through the LPLEGR passage 510, that is, the LPLEGR amount is controlled according to the open / close state. It is configured to be able to. The driving device of the LPLEGR valve 530 is electrically connected to the ECU 100, and the opening / closing state of the valve body of the LPLEGR valve 530 is controlled by the ECU 100 to the upper level.

  An air-fuel ratio sensor 221 configured to detect the air-fuel ratio AFsens in the exhaust downstream of the DPNR 400 is installed between the DPNR 400 and the branch position related to the LPLEGR passage 510 in the exhaust pipe 213. The air-fuel ratio sensor 221 is electrically connected to the ECU 100, and the detected air-fuel ratio AFsens is referred to by the ECU 100 at a constant or indefinite period.

<Operation of Embodiment>
In the DPNR 400, as described above, it is necessary to appropriately reduce the NOx stored in the NSR catalyst 430. At that time, the exhaust is temporarily made rich in fuel by fuel injection from the exhaust addition valve 220 (hereinafter, such control is referred to as “rich spike” as appropriate). The rich spike promotes the oxidation reaction in the CCO 410, the temperature of the NSR catalyst 430 is raised by the reaction heat, and NOx reduction in the NSR catalyst 430 proceeds. By such continuous regeneration in the DPNR 400, NOx is suitably purified, and at the same time, regeneration of the NSR catalyst 430 is favorably performed.

On the other hand, in the execution process of such a rich spike, the exhaust gas inevitably becomes fuel rich and the concentration of inactive CO _{2 in} the exhaust gas increases due to the necessity of supplying a large amount of reducing agent to the DPNR 400. To do. At this time, if the LPLEGR 500 is in operation, a part of this fuel-rich exhaust (hereinafter referred to as “rich spike atmosphere” where appropriate) branches to the LPLEGR passage 510 at the LPL branch position downstream of the DPNR 400. , It passes through the LPLEGR valve 530 and is recirculated as LPLEGR gas from the LPL merge position upstream of the compressor 216 to the intake system. However, in this case, the LPLEGR gas is supplied to the intake manifold 206 via the compressor 216 because the rich spike atmosphere has an excess of CO 2, that is, an oxygen shortage, unlike normal (ie, rich spike non-execution) exhaust. Inhalation (a mixture of intake air and LPLEGR gas) generally tends to be deficient in oxygen. For this reason, if no countermeasures are taken, misfires and insufficient torque are likely to occur in the combustion chamber (if a large amount of CO2 is contained, the propagation of the flame becomes slow and the torque tends to decrease). Therefore, in the engine system 10, the ECU 100 executes the rich spike LPLEGR control and optimizes the LPLEGR gas amount during the rich spike.

  Now, with reference to FIG. 2, the details of the rich spike LPLEGR control will be described. FIG. 2 is a flowchart of LPLEGR control during rich spike.

  In FIG. 2, the ECU 100 determines whether or not the rich spike execution condition is satisfied (step S101). If the rich spike execution condition is not satisfied (step S101: NO), the control is terminated. In addition, the said control is control repeatedly performed by the period intrinsic | native to ECU100 after completion | finish.

  When the rich spike execution condition is satisfied (step S101: YES), the ECU 100 determines whether or not the execution condition is LPLEGR (that is, LPLEGR gas recirculation control using the LPLEGR 500) (step S102). When it is not the execution condition of LPLEGR (step S102: NO), the ECU 100 ends the control. When the rich spike execution condition is satisfied, of course, the ECU 100 controls the exhaust addition valve 220 to execute a predetermined amount of rich spike.

  When it is the rich spike execution condition and the LPLEGR execution condition (step S102: YES), the ECU 100 calculates various conditions related to the rich spike (step S103). Here, the various conditions refer to the in-cylinder intake amount Gcyl, the base intake air amount Gbase, and the fuel injection amount Gf. Note that “calculation” includes acquiring a detection value from a sensor and selecting a corresponding value from a map.

  Among these, the in-cylinder intake air amount Gcyl is selectively acquired from a map stored in advance in the ROM based on the intake manifold pressure Pin and the engine rotational speed Ne. The base intake air amount Gbase is the intake air amount when the rich spike is not executed, and here is the value of the intake air amount Ga detected by the air flow meter 218 at that time. The fuel injection amount Gf is the amount of fuel injected from the unit injector 208. In view of the fact that the unit injector 208 is driven and controlled by the ECU 100, the ECU 100 itself grasps it as a control amount.

  When these various conditions are calculated, the ECU 100 calculates the rich spike movement speed that is the speed of the rich spike atmosphere (step S104). Here, the rich spike moving speed is related to the number of cycles of the engine 200. That is, the rich spike atmosphere reaches the LPLEGR valve 530 when a predetermined cycle determined according to the physical configuration of the engine 200 has elapsed. If the engine rotation speed Ne is known, the time required for the predetermined cycle to be elapsed can be calculated as a value corresponding to the engine rotation speed Ne, and the ECU 100 determines the rich time from the time required for the predetermined cycle to elapse. Calculate the spike movement speed.

  When the rich spike moving speed is calculated, the ECU 100 determines whether or not the drive control of the LPLEGR valve 530 is in time after the air-fuel ratio sensor 221 detects the air-fuel ratio (step S105). At this time, the ECU 100 determines that the rich spike arrival time calculated from the distance from the air-fuel ratio sensor 221 to the LPLEGR valve 530 and the rich spike moving speed includes physical, mechanical, or electrical factors of the LPLEGR valve 530. More than the operation delay time (the time required for the valve to actually move to the target opening after the control signal is supplied, or the time required for determining the target opening is added to the operation delay time) If it is short, it is determined that the drive control of the LPLEGR valve 530 is not in time.

  When the drive control is in time (step S105: YES), the ECU 100 calculates a target intake air amount Gatg, which is a target value of the intake air amount, from the air-fuel ratio AFsens detected by the air-fuel ratio sensor 221 according to the following relational expression (1). (Step S106). Further, since the air-fuel ratio sensor 221 detects AFsens at a predetermined cycle, the target intake air amount Gatg is also calculated momentarily and temporarily stored in the RAM.

Gatg = Gcyl × ((Gcyl-Gabase) × Gf × AFsens) / Gabase (1)
On the other hand, when the drive control is not in time (step S105: NO), the ECU 100 calculates the target air-fuel ratio Gatg according to the relational expression (1) based on the reference air-fuel ratio AFpat stored in advance in the ROM. The reference air-fuel ratio AFpat is a value obtained by schematically modeling the propagation characteristics of the rich spike atmosphere in advance by experiment or adaptation based on simulation or the like, and the time elapsed after the rich spike atmosphere reaches the air-fuel ratio sensor 221. It is stored as a corresponding pattern.

  When the target intake air amount Gatg is calculated, the ECU 100 determines that the rich spike atmosphere that has passed through the air-fuel ratio sensor 221 reaches the LPLFGR valve 530, the rich spike arrival time described above, and the rich spike atmosphere causes the LPLEGR valve 530 to pass. The rich spike arrival time, which is the time when the rich spike atmosphere reaches the LPL valve 530, is calculated from the reference time, which is the passing time (step S108).

  When the rich spike arrival time is calculated, the ECU 100 determines the control start time (step S109). Here, the control start time is a time determined so that the intake air amount Ga becomes the target intake air amount Gatg at the rich spike arrival time in consideration of the operation delay of the LPLEGR valve 530 described above. In addition, the time corresponding to the operation delay is given as an absolute time (for example, about several tens of msec), and the rich spike arrival time is given as the crank position in the control logic of the engine system 10. . Accordingly, in step S109, the ECU 100 calculates the control start time as the crank position by converting the operation delay time into the crank position and then subtracting it from the rich spike arrival time (that is, speeding it up on the time axis).

  The ECU 100 determines whether or not the control start time has come (step S110). When the control start time does not come (step S110: NO), the ECU 100 waits until the control start time comes, and when the control start time comes (step S110: YES), starts driving control of the LPLEGR valve 530. (Step S111). When the drive control of the LPLEGR valve 530 is started, the rich spike time LPLEGR control is ended. Note that the drive control of the LPLEGR valve 530 according to step S111 is performed so that the intake air amount Ga becomes the target intake air amount Gatg that is sequentially set and stored according to the air-fuel ratio AFsens that changes every moment. It is executed sequentially on the time axis. The control amount of the LPLEGR valve 530 for obtaining the target intake air amount Gatg (for example, the opening degree of the LPLEGR valve 530) corresponds to the LPLEGR amount obtained by subtracting the target intake air amount Gatg from the intake amount Gcyl. Is set as the control amount.

  Here, the effect of this embodiment will be described with reference to FIG. FIG. 3 is a schematic timing chart illustrating an hour characteristic of each index value related to the rich spike time LPLEGR control.

  In FIG. 3, the air-fuel ratio AFsens, the opening instruction value of the LPLEGR valve 530, the actual opening of the LPLEGR valve 530, and the time characteristics of the intake air amount Ga are sequentially shown from the upper stage.

  In FIG. 3, if the rich spike control is started at time T0, the air-fuel ratio sensor 221 detects the air-fuel ratio of the rich spike atmosphere at time T1. That is, after time T1, the air-fuel ratio AFsens starts to decrease from the reference value (that is, AFsens before the start of rich spike control) to indicate that the fuel is rich.

  In response to the detected air-fuel ratio AFsens, the opening instruction value of the LPLEGR valve 530 (namely, the target intake air amount Gatg) is set at time T2, and the driving of the LPLEGR valve 530 is started (ie, The time T2 is a time corresponding to the control start time). On the other hand, when the opening degree instruction value of the LPLEGR valve 530 is set, the time T3 delayed by the time corresponding to the operation delay described above (that is, the time corresponding to the rich spike arrival time), the LPLEGR valve is actually set. The opening of 530 begins to change.

  As a result, the intake air amount Ga starts to increase from time T3. At this time, since the intake air amount Ga is a value determined so that the oxygen concentration in the intake air becomes constant, the oxygen concentration in the intake air is kept constant. The increase in the intake air amount Ga is such that the air-fuel ratio AFsens returns to the reference value at time T4 (that is, the passage of the rich spike atmosphere is completed), and the drive control of the LPLEGR valve 530 is completed at time T5. Accordingly, when the opening degree of the LPLEGR valve 530 is actually returned to the original value at time T6, the intake air amount Ga is returned to the original value at time T6. As described above, according to the rich spike time LPLEGR control according to the present embodiment, the oxygen concentration in the intake air is accurately made constant based on the exhaust air-fuel ratio AFsens detected by the air-fuel ratio sensor 221 installed downstream of the DPNR 400. It can be maintained. At this time, the rich spike arrival time at which the rich spike atmosphere reaches the LPLEGR valve 530 is preferably calculated accurately and simply based on the number of cycles of the engine 200. Further, if the drive control of the LPLEGR valve 530 is not in time after detecting the air-fuel ratio due to the high engine speed at the time of rich spike execution, etc., based on the preset reference air-fuel ratio AFpat, Since the optimum target intake air amount Gatg is set as much as possible, the intake air amount Ga can be optimized under a wide range of operating conditions.

  The reference air-fuel ratio AFpat is corrected according to the engine speed Ne. Here, the reference air-fuel ratio AFpat will be described visually with reference to FIG. FIG. 4 is a schematic view illustrating the time characteristic of the reference air-fuel ratio AFpat.

In FIG. 4, the reference air-fuel ratio AFpat is expressed as PRF_BASE (see solid line). The reference air-fuel ratio AFpat is an air-fuel ratio pattern at a preset reference rotational speed. For example, when the engine rotational speed is lower than the reference rotational speed (that is, a long time is required for a predetermined number of cycles to elapse). When the rich spike moving speed is low), the characteristic is corrected to be more gradual with respect to the passage of time as shown in PRF_1 (see the broken line). As described above, the reference air-fuel ratio AFpat is corrected according to the engine rotational speed Ne, so that even if the drive control of the LPLEGR valve 530 is not in time after the actual air-fuel ratio is detected, the target intake air The amount Gatg can be calculated suitably.
Second Embodiment
Next, details of the rich spike time LPLEGR control according to the second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart of the rich spike time LPLEGR control according to the second embodiment. In the figure, the same reference numerals are given to the same portions as those in FIG. 3, and the description thereof will be omitted as appropriate.

  In FIG. 5, when the control start time is determined, the ECU 100 determines whether or not a change has occurred in the base intake air amount Gbase (step S201). If no change has occurred in the base intake air amount Gbase (step S201: NO), the process proceeds to step S110. On the other hand, if the base intake air amount Gbase has changed (step S201: YES), the ECU 100 corrects the target intake air amount Gbase (step S202).

  Here, with reference to FIG. 6, the correction | amendment aspect of target intake air amount Gatg is demonstrated. FIG. 6 is a schematic timing chart showing the time characteristic of the target intake air amount Gatg when correction is made.

  In FIG. 6, it is assumed that the base intake air amount Gbase increases by ΔGa, for example, when the driver performs an accelerator operation at time T10. In this case, according to the relational expression (1), the originally required target intake air amount Gatg also changes. Accordingly, the target intake air amount Gatg is increased and corrected by the correction amount ΔGa ′ corresponding to the change ΔGa in the base intake air amount Gabase at time T10 by the processing according to step S202 in FIG. In FIG. 6, the corrected target intake air amount Gatg is represented by a solid line, and the characteristics of the target intake air amount Gatg when no correction is made are represented by a broken line. That is, if correction is not made, the target intake air amount Gatg becomes inappropriate, and the combustion state of the combustion chamber changes during execution of rich spike, resulting in problems such as misfire or torque reduction. However, according to the second embodiment, For example, if the drive control of the LPLEGR valve 530 is earlier than the control start timing, the correction according to the change amount of the base intake air amount Gbase is made, so that the oxygen concentration in the intake is executed as a rich spike. It can be maintained as much as possible before and after.

  When the base intake air amount Gbase changes after the drive control of the LPLEGR valve 530 is started, the ECU 100 sequentially sets the target intake air amount from the timing in time for starting the drive control according to the current base intake air amount Gbase. Gatg correction is executed. For this reason, even if the base intake air amount Gbase changes after the drive control of the LPLEGR valve 530 is started, the oxygen concentration in the intake air is maintained as constant as possible before and after execution of the rich spike.

  The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention.

1 is a schematic configuration diagram conceptually showing a configuration of an engine system according to a first embodiment of the present invention. 2 is a flowchart of LPLEGR control during rich spike executed by an ECU in the engine system of FIG. 1. 4 is a schematic timing chart illustrating an hour characteristic of each index value related to the control of FIG. 3. It is a schematic diagram which illustrates the time characteristic of reference | standard air fuel ratio AFpat. It is a flowchart of LPLEGR control at the time of rich spike according to the second embodiment. It is a typical timing chart showing the time characteristic of the target intake air amount Gatg when correction according to the change of the base intake air amount is made.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine system, 100 ... ECU, 200 ... Engine, 220 ... Exhaust gas addition valve, 221 ... Air-fuel ratio sensor, 300 ... HPLEGR, 400 ... DPNR, 430 ... NSR catalyst, 500 ... LPLEGR, 510 ... LPLEGR passage, 530 ... LPLEGR valve.

Claims (6)

An internal combustion engine;
An exhaust purification means including at least a catalyst capable of storing NOx configured to purify exhaust of the internal combustion engine;
Enriching means capable of fuel enriching the exhaust with respect to a reference state;
An intake air of the internal combustion engine having a flow rate control valve and using a part of the exhaust gas whose flow rate is defined according to the open / closed state of the flow rate control valve at a branch position set downstream of the exhaust gas purification means as LPLEGR gas An LPLEGR device that can be refluxed to the system;
A vehicle control apparatus comprising: a detection unit capable of detecting a physical quantity corresponding to an air-fuel ratio of the exhaust gas on a downstream side of the exhaust purification unit and an upstream side of the branch position;
First control means for controlling the enrichment means so that the exhaust is enriched in fuel when a predetermined execution condition is satisfied;
Based on the detected physical quantity, the target intake air amount that is the target value of the intake air quantity so that the oxygen concentration in the intake air sucked into the cylinder of the internal combustion engine is constant before and after the exhaust is enriched with fuel. A setting means for setting
A specifying means for specifying an arrival time as a time when the fuel-rich exhaust reaches the flow control valve;
Second control means for controlling the flow rate control valve in consideration of a response delay of the flow rate control valve so that the intake air amount becomes the set target intake air amount at the specified arrival time. A control apparatus for a vehicle. The vehicle control device according to claim 1, wherein the specifying unit specifies the arrival time based on a cycle number of the internal combustion engine. Comprising a determining means for determining whether the specified arrival time precedes the control start time of the flow control valve;
The setting means, when it is determined that the specified arrival time is ahead of the control start time of the flow control valve, the estimated physical quantity corresponding to the physical quantity corresponding to the exhaust after the fuel enrichment is set in advance. Based on the target intake air amount,
The second control means controls the flow rate control valve so that the intake air amount becomes a target intake air amount set based on the estimated physical quantity at the specified arrival time. The vehicle control device according to 1 or 2. The vehicle control device according to claim 3, further comprising first correction means for correcting the estimated physical quantity in accordance with an engine speed of the internal combustion engine. The setting means sets the target intake air amount on the basis of the base intake air amount that is the intake air amount when the exhaust is not enriched and the detected physical amount,
A second correcting means for correcting the target intake air amount according to the change amount according to the change when the base intake air amount changes;
The vehicle according to any one of claims 1 to 4, wherein the second control unit controls the flow rate control valve so that the intake air amount becomes the corrected target intake air amount. Control device. The second correction means corrects the target intake air amount according to the base intake air amount at the present time when the control of the flow control valve according to the set target intake air amount is started. The vehicle control device according to claim 5.

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