JP3355872B2 - Engine excess air ratio detection device and exhaust gas recirculation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for detecting an excess air ratio of an engine and a system for controlling exhaust gas recirculation, which are used in a fuel supply system such as an automobile diesel engine or an exhaust gas purification system.

[0002]

2. Description of the Related Art The main harmful emission components of diesel engines include black smoke and unburned HC due to uneven fuel distribution.
Other like include NO _X due to combustion at high temperatures. The NO _X reduction means in a diesel engine, can not be reduced catalyst applications, such as gasoline engine for surplus oxygen is large, the fuel injection timing delay (timing retard) or water injection is studied. However, in the former case, the output and fuel consumption are inevitably reduced and CO and HC are increased. In the latter case, there are problems such as mounting of a water injection device and a water tank and mixing of water into lubricating oil. Therefore, practical use of an exhaust gas recirculation (EGR) device for recirculating exhaust gas, which is an inert substance, as EGR gas to a combustion chamber is being promoted because of its relatively simple structure and little adverse effect.

In an EGR device for a diesel engine,
When the recirculation amount of the EGR gas (hereinafter, referred to as EGR amount) becomes excessive, smoke emission is deteriorated due to a decrease in the excess air ratio, a sudden increase in HC, fuel consumption is reduced, and engine oil due to mixing of free carbon and particulates is reduced. Deterioration causes a decrease in engine durability and the like. Therefore, in order to the reduce of the NO _X while suppressing these problems as much as possible, by detecting the excess air ratio, electronically controlled for feedback controlling the EGR amount it is desirable. As a method of detecting the excess air ratio, there are a method using a CO ₂ analyzer and a method using a linear air-fuel ratio sensor (hereinafter, LA).
FS) is generally used.

However, as is well known, the CO ₂ analyzer can be used for bench tests and the like because of its large size and weight, but is not practical for use in vehicles. On the other hand, L
Japanese Patent Application Laid-Open No. 55-79 discloses an EGR device using AFS.
No. 64 and JP-A-63-201356. In the former EGR device, LA is added to the exhaust system.
The FS is mounted, and when the output current exceeds a predetermined threshold, the EGR valve is driven in the opening direction, and when the output current falls below the predetermined threshold, the EGR valve is driven in the closing direction. In the latter EGR device, the EGR amount is controlled based on an EGR amount control map using the lever opening of the fuel injection pump and the engine speed as parameters.
LAFS attached to exhaust system while driving R valve
The correction of the EGR valve opening degree (control map) is performed by the following.

[0005]

However, these LAs
EGR for feedback control of EGR amount using FS
The device also has the following problems. For example, LAF
Since S is attached to the exhaust system, even if the excess air ratio actually changes, a transfer delay occurs before the exhaust gas reaches LAFS. Further, the LAFS has a structure that outputs a current corresponding to the excess air ratio based on the principle of the oxygen concentration cell, and the exhaust gas reaches the element through the protection tube, so that the response itself to the change in the excess air ratio is low. .
Therefore, at the time of acceleration or deceleration in which the excess air ratio changes rapidly, as shown in FIG.
There is a delay (usually more than a dozen strokes) until is detected.
FIG. 5 shows a case where the fuel injection amount is rapidly increased. The solid line shows the actual change in the excess air ratio, and the two-dot chain line shows the detection result by LAFS. Therefore, naturally it delayed in the control of the EGR device occurs, there is a problem that NO _X emissions or black smoke emissions increases. In particular, immediately after acceleration where black smoke is likely to be emitted,
There was a problem that the emission of black smoke further increased.

Further, in a diesel engine, since the exhaust gas contains a large amount of free carbon and particulates, LAFS is contaminated in a short period of time, and there is a problem that a current corresponding to the excess air ratio is not output. As a result, the detection accuracy gradually deteriorates, and the control of the EGR amount cannot be performed accurately. In addition, since the LAFS itself is an expensive component, not only the initial cost is high, but also the running cost due to periodic inspection and replacement is reduced. There was also the problem of getting higher.

The present invention has been made in view of the above circumstances, and uses an excess air ratio detection device and a principle thereof capable of quickly detecting an excess air ratio of a diesel engine or the like while adopting a relatively simple and inexpensive device configuration. It is an object of the present invention to provide an exhaust gas recirculation control device.

[0008]

Therefore, according to the first aspect of the present invention, when the exhaust gas recirculation device of the engine is operating, the engine is supplied to the engine based on the operating state of the engine mounted on the vehicle. An intake air pressure detection means for detecting an intake air pressure of the engine, and introduction of recirculated exhaust gas by the exhaust gas recirculation device in an intake passage of the engine. An air flow sensor provided upstream of the mouth and detecting a fresh air amount flowing through the intake passage; based on the intake air pressure detected by the intake air pressure detecting means and the fresh air amount detected by the air flow sensor Exhaust gas recirculation amount estimating means for estimating the amount of exhaust gas recirculation by the exhaust gas recirculation device, and detection by the air flow sensor The equivalent intake fresh air amount of the engine is estimated based on the estimated fresh air amount, the exhaust gas recirculation amount estimated by the exhaust gas recirculation amount estimating means, and the excess air ratio estimated a predetermined number of times before. An equivalent intake fresh air amount estimating means, a fuel supply amount detecting means for detecting a fuel supply amount of the engine, a fuel supply amount detected by the fuel supply amount detecting means, and an estimation by the equivalent intake fresh air amount estimating means. The present invention further proposes an engine having an excess air ratio estimating means for estimating the excess air ratio of the engine based on the calculated equivalent intake fresh air amount.

According to a second aspect of the present invention, in the excess air ratio detecting device according to the first aspect, the in-cylinder intake fresh air amount is estimated as a portion of the fresh air amount detected by the air flow sensor which is sucked into the cylinder. And a cylinder intake new air amount estimating means. In a preferred embodiment ,
3. The excess air ratio detecting device according to claim 2, wherein the in-cylinder intake fresh air amount estimating means calculates the in-cylinder fresh air amount based on a previous value of the in-cylinder intake fresh air amount and a current value of the new air amount detected by the air flow sensor. It is preferable to estimate the intake fresh air amount.

[0010] According to claim 3, in the excess air rate detecting apparatus according to claim 1 or 2 wherein said exhaust gas recirculation quantity estimating means, instead of the exhaust gas based on the total intake air amount of the engine which is estimated from the intake pressure We propose something to estimate the flow rate. As a preferred embodiment , in the air excess ratio detecting device according to claim 3 , the exhaust gas recirculation amount estimating means estimates the exhaust gas recirculation amount by subtracting the in-cylinder intake fresh air amount from the total intake amount. Good thing.

According to a fourth aspect of the present invention, in the air excess ratio detecting device according to the first to third aspects, the equivalent intake new air amount estimating means includes the exhaust gas recirculation amount and the exhaust gas recirculation amount in the cylinder fresh air amount. we propose to estimate the equivalent intake fresh air amount by the addition of non-fuel-air vapor content in place Nagarehai air gas estimated from the excess air ratio. In a preferred embodiment, claims 1 to 4 are provided.
In the above-described excess air ratio detection device, the excess air ratio estimation means preferably estimates the excess air ratio for each stroke of the engine.

In a further preferred aspect, in the air excess ratio detecting device according to any one of claims 1 to 4, the engine is preferably a diesel engine. According to a fifth aspect, the engine according to any one of the first to third aspects is provided.
Provided with a down excess air rate detecting apparatus, based on the operating condition of an engine mounted on a vehicle, the exhaust gas recirculation control device for controlling the opening amount of the exhaust gas recirculation system of the engine, on SL engine Target excess air ratio setting means for setting a target excess air ratio of the supplied air-fuel mixture;
Valve opening amount setting means for setting a target valve opening amount of the exhaust gas recirculation device so that a deviation between the excess air ratio detected by the excess air ratio detection device and the target excess air ratio is eliminated;
A drive control device for controlling the drive of the exhaust gas recirculation device based on the target valve opening amount is proposed.

According to a sixth aspect of the present invention, in the exhaust gas recirculation control device according to the fifth aspect, the target excess air ratio setting means sets the target excess air ratio based on an engine speed and a fuel supply amount. Suggest. Also preferred
As an aspect , in the exhaust gas recirculation control device according to claim 5 or 6 , the valve opening amount setting means sets the valve opening amount by at least proportional integral control, and the absolute value of the deviation is a predetermined value. If it is larger, the integral term in the proportional integral control is not integrated .
Is good .

[0014]

[Action] In the excess air rate detecting apparatus according to claim 1, the exhaust gas recirculation quantity estimating means to estimate the exhaust gas recirculation amount from the fresh air amount detected by an intake pressure and the air flow sensor has detected that the intake pressure detecting means Later, the equivalent intake fresh air amount estimating means
An equivalent intake new air amount is estimated from the new air amount, the exhaust gas recirculation amount, and the excess air ratio several strokes ago, and the excess air ratio estimating means is detected by the equivalent intake new air quantity and the fuel supply amount detecting means. The excess air ratio is estimated from the fuel supply amount.

In the air excess ratio detecting device according to a second aspect of the present invention, the in-cylinder fresh air amount estimating means considers a transfer delay by the intake pipe with respect to the fresh air amount detected by the air flow sensor. Estimate fresh air volume. In a preferred aspect of the excess air ratio detecting device according to claim 2 , the in-cylinder fresh air amount estimating means uses a smoothing coefficient based on a previous value of the in-cylinder fresh air amount and a current value of the fresh air amount. To estimate the in-cylinder intake fresh air amount.

Further, in the excess air rate detecting apparatus according to claim 3, the exhaust gas recirculation quantity estimating means, the total intake air amount of the engine from the intake pressure detecting unit intake pressure is detected and the fuel supply amount and the engine rotational speed The exhaust gas recirculation amount is estimated based on the total intake amount and the fresh air amount. Further, in the preferred embodiment of the excess air ratio detecting apparatus according to claim 3, the exhaust gas recirculation quantity estimating means, the total intake air amount of the engine from the intake pressure detecting unit intake pressure is detected and the fuel supply amount and the engine rotational speed Then, the exhaust gas recirculation amount is estimated by subtracting the in-cylinder intake fresh air amount from the total intake air amount.

Further, in the excess air ratio detecting device according to the fourth aspect , the equivalent intake fresh air amount estimating means estimates the amount of unburned air in the recirculated exhaust gas based on the excess air ratio several strokes ago, and calculates the estimated amount. The equivalent intake fresh air amount is estimated by adding to the internal intake fresh air amount. In addition, it is preferable that the excess air ratio detection device according to claims 1 to 4 be used.
In a preferred embodiment , the excess air ratio estimating means estimates the excess air ratio at the start of the intake stroke of each cylinder, based on an output signal from a crank angle sensor or the like.

An excess air ratio detecting device according to any one of claims 1 to 4.
In a more preferred embodiment , the excess air ratio can be stably detected even if the exhaust gas contains a large amount of free carbon and particulates. Further, in the exhaust gas recirculation control device according to claim 5 , the deviation between the detected excess air ratio and the target excess air ratio is obtained, and if the current state is rich, the valve opening amount of the exhaust gas recirculation device is reduced. The fresh air amount is increased, and conversely, if it is in a lean state, the valve opening amount of the exhaust gas recirculation device is increased to decrease the fresh air amount.

In the exhaust gas recirculation control device according to a sixth aspect of the present invention, the target excess air ratio setting means sets the target excess air ratio based on, for example, a map using the engine speed and the fuel supply amount as parameters. Claim 5 or 6
In a preferred aspect of the exhaust gas recirculation control device, the valve opening amount setting means stops the integration of the integral term when the absolute value of the deviation is larger than a predetermined value, so that the absolute value of the integral term does not become excessive. I do.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an excess air ratio detecting apparatus and an exhaust gas recirculation control apparatus according to the present invention. Figure 1 is a schematic configuration diagram of an engine control system EGR device is attached, 1 in the figure shows an inline four-cylinder diesel engine for an automobile (hereinafter, simply referred to as engine) a. A swirl chamber 3 is formed in a cylinder head 2 of the engine 1, and a fuel injection nozzle 4 for injecting fuel into the swirl chamber 3 is attached to each cylinder. The engine 1 is provided with a distribution type fuel injection pump 6 having an electronic governor 5, and supplies fuel to each fuel injection nozzle 4 via a fuel injection pipe 7. The fuel injection pump 6 is driven by a crankshaft (not shown) of the engine 1, and a fuel injection timing and an injection period are set by an electronic governor 5 controlled by an ECU (engine control unit) 8. In the drawing, reference numeral 9 denotes a water temperature sensor attached to the cylinder head 2 for detecting a cooling water temperature Tw, and reference numeral 10 denotes a Ne sensor attached to the fuel injection pump 6 for detecting an engine rotation speed Ne.

An intake pipe 12 for introducing fresh air from an air cleaner (not shown) is connected to the cylinder head 2 via an intake manifold 11, and the pipeline is connected to a compressor 14 of a turbocharger 13 and an intake pipe 12. A cooler 15 is provided. In the figure, 16 is an intake air temperature sensor for detecting the intake air temperature Ta, and 17 is an intake pipe pressure (Manifold Absolut).
e Pressure) A boost pressure sensor for detecting Pb, and 18 is a Karman vortex airflow sensor for detecting a fresh air amount Qaf, all of which are attached to the intake manifold 11. The turbine 21 of the turbocharger 13 and an exhaust pipe 22 are connected to the cylinder head 2 via an exhaust manifold 20. In the figure, reference numeral 23 denotes a wastegate valve for releasing exhaust gas from the exhaust manifold 20 to the downstream of the turbine 21 when the boost pressure is excessively increased, and reference numeral 24 denotes a wastegate actuator. An oxidation catalyst 25 purifies CO and HC in the exhaust gas.

On the other hand, the exhaust manifold 20 and the downstream side of the air flow sensor 18 of the intake manifold 11 are connected to the EGR.
The EGR pipe 30 is connected to an EG provided on the intake manifold 11 side.
The valve body 32 of the R valve 31 opens and shuts off. The EGR valve 31 is of a negative pressure operation type, and includes a valve body 32, a diaphragm 33, a return spring 34, and a negative pressure chamber 35. In the figure, reference numeral 36 denotes an EGR position sensor for detecting the opening A _E of the EGR valve 31.

The negative pressure chamber 35 of the EGR valve 31 has a hose 4
The vacuum pump 43 is connected to the vacuum pump 43 via the negative pressure side EGR solenoid 42 and the negative pressure side EGR solenoid 42, and is connected to the atmosphere via a hose 44 and the atmosphere side EGR solenoid 45. The vacuum pump 43 is driven by the rotating shaft of the alternator 46, and always generates a negative pressure during operation of the engine 1. The negative pressure side EGR solenoid 42 communicates with the hoses 40 and 41 in the ON state, and connects the hoses 40 and 4 in the OFF state.
Block 1 The atmosphere side EGR solenoid 45 is O
The hose 44 communicates with the atmosphere in the FF state, and is shut off in the ON state. Therefore, both EGR solenoids 4
By turning on and off 2 and 45 as appropriate,
The negative pressure or the atmosphere is introduced into the negative pressure chamber 35 of the EGR valve 31, and the opening A _E of the EGR valve 31 is controlled.

The above-described ECU 8 is installed in the vehicle interior, and includes an input / output device (not shown), a storage device (ROM, RAM, etc.) containing a control program, and a central processing unit (CP).
U) etc. On the input side of the ECU 8, detection information from various sensors and switches, including the above-described sensors, is input. Based on the detection information and the control map, the ECU 8 performs both EGR including the electronic governor 5. Drive control of the solenoids 42 and 45 and the like is performed.

Hereinafter, the procedure for detecting the excess air ratio and the procedure for controlling the EGR device in this embodiment will be described. When the driver turns on the ignition key and the engine 1 starts, a predetermined control condition (in this embodiment, the water temperature TW is 70
° C or more, 30 seconds or more after starting, boost pressure sensor 17
And that the EGR position sensor 36 is normal, etc.), the ECU 8 sets
The excess air ratio detection subroutine shown in the flowchart of FIG. 2 is repeatedly executed. When this subroutine is started, the ECU 8 first determines in step S2 that the intake air temperature sensor 1
6, the total intake air amount Q _{IN (i)} (g / st) to be sucked into the engine 1 is calculated by the following equation based on the output of the boost pressure sensor 6 and the boost pressure sensor 17. In the following equation, Pb is the intake pipe pressure (mmH
₂ O), V is the displacement (l) per cylinder, and K _VE is the engine speed Ne (rpm) and the intake pipe pressure P
is a volume efficiency correction coefficient obtained from a map (not shown) based on b, and Ta is the intake air temperature (° C.) Q _{IN (i)} = (Pb / 760) · V · K _VE · 1.2 · (293 / (273 + Ta) Next, the ECU 8 determines in step S4 that the airflow sensor 1
After reading the new air amount Qaf detected by the air flow sensor 8, the in-cylinder intake fresh air amount Qfa _(i) is taken into consideration in step S6 in consideration of the time delay until the fresh air passing through the air flow sensor 18 is sucked into the cylinder. ₎ Is calculated by the following equation. Where Qfa _(i-1)
Is the previous value of the in-cylinder intake fresh air amount, and k is the smoothing coefficient obtained using the surge tank model.

Qfa_(i)＝ k ・ Qfa_(i-1)+ (1-k) ・ Qaf (However
0 <k <1) Next, the ECU 8 determines in step S8 that the total intake air amount Q_{IN (i)}
And in-cylinder intake fresh air Qfa _(i)From this, the EGR amount Q_{E (i)}Below
It is calculated by the formula. Q_{E (i)}= Q_{IN (i)}−Qfa_(i) EGR amount Q_{E (i)}Is obtained, the ECU 8 proceeds to the next step
At S10, the in-cylinder intake fresh air amount Qfa_(i)Unburned in EGR gas
By adding air, the equivalent intake fresh air Qa_(i) Calculate
You. Where λ_(i-3)Is the estimated excess air ratio three strokes ago
The second processing from the start of the subroutine (that is,
Until the second stroke), a predetermined value (for example, 1.2) is set.
ing.

Qa _(i) = Qfa _(i) + (1-1 / λ _(i-3) ) QE _{(i )} Next, the ECU 8 calculates the equivalent intake fresh air amount Qa thus obtained. _{From (i)} and the fuel injection amount Qf, step S12
Then, the current air-fuel ratio Af _(i) is calculated by the following equation. Af _(i) = Qa _(i) / Qf When the calculation of the air-fuel ratio Af _(i) is completed, the ECU 8 finally ends the present air excess ratio λ _{(i) according} to the following equation in step S14.
Is calculated, and the process returns to the start to repeat the detection of the excess air ratio. Here, 14.5 is the stoichiometric air-fuel ratio of the diesel engine.

Λ _(i) = Af _(i) /14.5 Note that the detected estimated excess air ratio λ _(i) is equal to a predetermined lower limit λ.
s or less, the ECU 8 executes the EGR valve 3 in an EGR control subroutine described later to suppress the emission of black smoke.
In addition to increasing the equivalent intake fresh air amount Qa _(i) by controlling the driving of the electronic governor 1 in the valve closing direction, the electronic governor 5 is also driven and controlled to gradually reduce the fuel injection amount Qf in a fuel injection control subroutine not described here.

On the other hand, in parallel with the excess air ratio detection subroutine, the ECU 8 executes an EGR control subroutine shown in the flowcharts of FIGS. When this subroutine is started, the ECU 8 first proceeds to step S20
Then, after reading the current estimated excess air ratio λ _(i) obtained by the excess air ratio detection subroutine from the RAM, in step S22, the engine rotation speed Ne and the fuel injection amount Qf are read.
And the target excess air ratio λta
Search for rget.

Next, in step S24, the ECU 8 calculates a deviation Δλ between the target excess air ratio λtarget and the estimated excess air ratio λ _(i) by the following equation. Δλ = λtarget−λ _(i) Next, in steps S26 and S28, the ECU 8 calculates the proportional term EP and the integral term EI of the EGR control by using the proportional gain Kp and the integral gain KI by the following equations.
In calculating the integral term EI, the absolute value of the deviation | Δλ |
Is larger than the predetermined upper limit Dλ _O , Δλ is set to 0. This is because if the absolute value of the deviation | Δλ |
When the deviation Δλ is integrated as it is, the absolute value of the integral term EI |
This is because EI | becomes too large, and the control followability to the change in the operating state is deteriorated.

After calculating the proportional term EP and the integral term EI, the ECU 8 calculates the following equation: EP = KP · Δλ EI = KI · ∫Δλ
In step S30 of FIG. 4, a basic correction value EPI is calculated by the following equation. EPI = EP + EI Next, in step S32, the ECU 8 performs a limiter process of clipping the calculated basic correction value EPI at predetermined upper and lower limits, and determines the opening correction value Eposc of the EGR valve 31.

Next, in step S34, the ECU 8 searches the map for the basic opening Eo of the EGR valve 31 based on the engine speed Ne and the fuel injection amount Qf.
At 36, the target EGR valve opening Epos is calculated by the following equation. Epos = Eo + Eposc Next, the ECU 8 controls the driving of the EGR valve 31 based on the target EGR valve opening Epos in step S38, and then returns to the start and repeats the control.

As described above, in the above-described embodiment, the excess air ratio is estimated based on the fresh air amount, the intake pressure fuel injection amount, and the like, so that accurate and quick operation is possible without using an expensive sensor such as LAFS. The excess air ratio can now be detected. Also, based on the detected excess air ratio, the EGR
By controlling the drive of the valve 31, the EGR gas can be appropriately recirculated even during acceleration, deceleration, and the like.
_X emissions were extremely low.

Although the description of the concrete embodiment has been completed above, embodiments of the present invention are not limited to this embodiment. For example,
In the above embodiment, the present invention is applied to a diesel engine having a turbocharger, but is also suitable for a naturally aspirated diesel engine, a lean burn gasoline engine, and the like. In the above embodiment, the Karman vortex air flow sensor is used. However, a hot wire type or vane type air flow sensor may be used, or the air flow sensor may be installed at another part of the intake system as long as it is upstream of the EGR gas inlet. May be. In addition, the EG
In the R control subroutine, the EGR control is performed using the excess air ratio estimated in the excess air ratio detection subroutine. However, the LAFS may be attached to an intake pipe or the like, and may be performed based on the detection result. . Further, the specific configuration and control procedure of the engine control system can be changed without departing from the gist of the present invention.

[0035]

According to the first aspect of the present invention, based on the operating state of the engine mounted on the vehicle, the air-fuel mixture supplied to the engine when the exhaust gas recirculation device of the engine is operating. An excess air ratio detection device for repeatedly detecting an excess air ratio of the engine, wherein an intake pressure detecting means for detecting an intake pressure of the engine, and an upstream side of a recirculated exhaust gas inlet of the exhaust gas recirculation device in an intake passage of the engine. An air flow sensor for detecting a fresh air amount flowing through the intake passage, and the exhaust gas based on the intake pressure detected by the intake pressure detecting means and the fresh air amount detected by the air flow sensor. An exhaust gas recirculation amount estimating means for estimating an exhaust gas recirculation amount by the recirculation device; a fresh air amount detected by the air flow sensor; Equivalent intake fresh air amount estimating means for estimating the equivalent intake fresh air amount of the engine based on the exhaust gas recirculation amount estimated by the exhaust gas recirculation amount estimating means and the excess air ratio estimated a predetermined number of times earlier. A fuel supply amount detecting means for detecting a fuel supply amount of the engine; a fuel supply amount detected by the fuel supply amount detecting means; and an equivalent intake fresh air amount estimated by the equivalent intake new air amount estimating means. And an excess air ratio estimating means for estimating the excess air ratio of the engine based on the above, so that the excess air ratio in the diesel engine or the like can be accurately and quickly determined without using a low-reliability and high-cost LAFS or the like. , And appropriate control of the fuel injection amount and the EGR amount can be performed in order to reduce the NO _X emission amount and the black smoke emission amount.

According to a second aspect of the present invention, in the excess air ratio detecting device according to the first aspect, the in-cylinder intake fresh air amount is defined as a portion of the fresh air amount detected by the air flow sensor which is sucked into the cylinder. Is further provided with an in-cylinder intake fresh air amount estimating means, whereby the excess air ratio can be accurately detected. In a preferable embodiment of the excess air rate detection device 請 Motomeko 2, the cylinder intake fresh air amount estimating means, this fresh air amount detected by the previous value and the air flow sensor in the cylinder intake fresh air amount It is preferable to estimate the in-cylinder intake fresh air amount from the value , so that even if there is a transfer delay due to the intake pipe or the surge tank, the excess air ratio during transient operation or the like can be accurately detected.

Further, according to claim 3, claim 1 or
In 2 of the excess air rate detecting apparatus, the exhaust gas recirculation quantity estimating means, due to be estimated exhaust gas recirculation amount based on the total intake air amount of the engine which is estimated from the intake pressure, the valve of the exhaust gas recirculation system The exhaust gas recirculation amount can be accurately estimated regardless of the opening degree or the like. In a preferable embodiment of the excess air rate detection device 請 Motomeko 3, the exhaust gas recirculation quantity estimating means, the exhaust gas recirculation quantity estimating means, subtracting the in-cylinder intake fresh air amount from the total intake air amount It is good to estimate the exhaust gas recirculation amount by
Thus , the amount of exhaust gas recirculation during transient operation or the like can be accurately estimated.

According to a fourth aspect of the present invention, in the air excess ratio detecting device according to the first to third aspects, the equivalent intake fresh air amount estimating means includes the in-cylinder intake fresh air amount and the exhaust gas recirculation amount. due to so as to estimate the equivalent intake fresh air amount by the addition of non-fuel-air air amount of the excess air ratio changing estimated from the Nagarehai air gas, so the excess air ratio can be accurately detected.

Further, the excess air rate detecting apparatus 請 Motomeko 1-4
In a preferred aspect , the excess air ratio estimating means performs the estimation of the excess air ratio for each stroke of the engine.
To well, thereby improving the control response, such as fuel injection amount and the EGR amount. Moreover, a further preferred embodiment of the excess air rate detection device 請 Motomeko 1-4, the engine may me diesel engines der, the excess air ratio in this case can be detected stably.

According to claim 5, according to claims 1 to 3,
The engine excess air ratio detection device according to any one of
Together provided, based on the operating condition of an engine mounted on a vehicle, the exhaust gas recirculation control device for controlling the opening amount of the exhaust gas recirculation system of the engine, the air-fuel mixture to be supplied to the upper SL engine target air The target excess air ratio setting means for setting the excess ratio and the excess air ratio detection device
Valve opening amount setting means for setting a target valve opening amount of the exhaust gas recirculation device so as to eliminate a deviation between the detected excess air ratio and the target excess air ratio, based on the target valve opening amount,
Since a drive control device for controlling the drive of the exhaust gas recirculation device is provided, it is possible to reduce the amount of NOx emission and the amount of black smoke emission in a diesel engine or the like.

According to a sixth aspect of the present invention, in the exhaust gas recirculation control device according to the fifth aspect , the target excess air ratio setting means sets the target excess air ratio based on the engine speed and the fuel supply amount. Thus, it is possible to reduce the amount of NOx emission and the amount of black smoke emission even during a transient operation or the like. In a preferable embodiment of the exhaust gas recirculation control device 請 Motomeko 5 or 6, the valve opening amount setting means is for setting the valve opening degree by at least proportional-integral control, the absolute value of the deviation If it is larger than the predetermined value,
It is preferable not to perform integration of the integral terms in the proportional integral control , thereby preventing deterioration of control responsiveness due to an excessively large integral term.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an engine control system according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a procedure of an excess air ratio detection subroutine.

FIG. 3 is a flowchart illustrating a procedure of an EGR control subroutine.

FIG. 4 is a flowchart showing a procedure of an EGR control subroutine.

FIG. 5 is a graph showing a change in an excess air ratio when the fuel injection amount is rapidly increased and a detection result obtained by a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder head 4 Fuel injection valve 5 Electronic governor 6 Fuel injection pump 8 ECU 11 Intake manifold 13 Turbocharger 14 Compressor 17 Boost pressure sensor 18 Air flow sensor 20 Exhaust manifold 21 Turbine 30 EGR pipe 31 EGR valve 42 Negative pressure side EGR Solenoid 43 Vacuum pump 45 Atmospheric EGR solenoid

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F02D 41/14 310 F02D 41/14 310P 45/00 301 45/00 301F (56) References JP-A-58-140461 (JP, A) JP-A-6-330821 (JP, A) JP-A-2-157438 (JP, A) JP-A-60-90932 (JP, A) JP-A-2-61347 (JP, A) JP-A-63 JP-A-176647 (JP, A) JP-A-55-72645 (JP, A) JP-A-4-203453 (JP, A) JP-A-55-7964 (JP, A) JP-A-63-201356 (JP, A) ) Hikaru 4-116654 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02M 25/07 550 F02M 25/07 570 F02D 41/14 310 F02D 45/00 301

Claims (6)

(57) [Claims] An excess air for repeatedly detecting an excess air ratio of an air-fuel mixture supplied to an engine based on an operating state of an engine mounted on a vehicle when the exhaust gas recirculation device of the engine is operating. An intake pressure detecting means for detecting an intake pressure of the engine; and an intake pressure detection means for detecting an intake pressure of the engine; An air flow sensor for detecting a new air amount to be generated; and an exhaust gas recirculation device for estimating an exhaust gas recirculation amount based on the intake air pressure detected by the intake air pressure detecting means and the new air amount detected by the air flow sensor. Exhaust gas recirculation amount estimating means, new air amount detected by the air flow sensor, and exhaust gas recirculation amount estimating means An equivalent intake fresh air amount estimating means for estimating an equivalent intake fresh air amount of the engine based on the estimated exhaust gas recirculation amount and the excess air ratio estimated a predetermined number of times ago; A fuel supply amount detecting means for detecting a supply amount; a fuel supply amount detected by the fuel supply amount detecting means; and an equivalent intake fresh air amount estimated by the equivalent intake new air amount estimating means. An excess air ratio detecting device for an engine, comprising: an excess air ratio estimating means for estimating an excess air ratio. 2. An in-cylinder fresh air amount estimating means for estimating an in-cylinder fresh air amount as a portion of the fresh air amount detected by the air flow sensor which is sucked into the cylinder. The engine excess air ratio detection device according to claim 1. Wherein said exhaust gas recirculation quantity estimating means, and estimates the exhaust gas recirculation amount based on the total intake air amount of the engine which is estimated from the intake pressure, claim 1 or
3. The apparatus for detecting an excess air ratio of an engine according to claim 2 . Wherein said equivalent intake fresh air amount estimating means, to the cylinder intake fresh air amount, the non-fuel-air vapor content in place Nagarehai air gas estimated from the aforementioned exhaust gas recirculation amount and the excess air ratio Characterized by estimating an equivalent intake fresh air volume by adding
The engine excess air ratio detection device according to claim 1. 5. The method according to claim 1, wherein
With an air excess ratio detecting device engine, based on operating conditions of an engine mounted on a vehicle, the exhaust gas recirculation control device for controlling the opening amount of the exhaust gas recirculation system of the engine, on SL engine Target excess air ratio setting means for setting a target excess air ratio of the supplied air-fuel mixture; and the exhaust gas so as to eliminate a deviation between the excess air ratio detected by the excess air ratio detection device and the target excess air ratio. Exhaust gas comprising: valve opening amount setting means for setting a target valve opening amount of a recirculation device; and a drive control device for driving and controlling the exhaust gas recirculation device based on the target valve opening amount. Recirculation control device. 6. An exhaust gas recirculation control device according to claim 5 , wherein said target excess air ratio setting means sets a target excess air ratio based on an engine speed and a fuel supply amount.