JP3161292B2 - Excess air ratio control device for turbocharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excess air ratio control device used to reduce harmful emission components of a turbocharged diesel engine mounted on an automobile or the like.

[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 reduce NO _X while suppressing these problems as much as possible, it is desirable to maintain the excess air ratio in an appropriate range not only during steady operation but also during transient operation.

On the other hand, many diesel engines are equipped with a turbocharger in order to increase the output per displacement. The turbocharger performs supercharging by using exhaust gas energy (exhaust pressure), and includes a turbine mounted on an exhaust manifold or the like and a compressor coaxially disposed in an intake system. ing. As is well known, the work amount of the turbocharger, i.e., the supercharging pressure, depends on the exhaust pressure, and is small in a low-load / low-speed range, and is high in a high-load / low-speed range.
It becomes large in the high rotation range. In addition, even if the fuel supply amount increases due to the driver's accelerator operation, it takes a little time for the exhaust pressure to rise due to transfer delay, etc. Since the rotation does not rise instantaneously, there is an inherent response delay (turbo lag).

[0005]

When an EGR device is mounted on a turbocharged diesel engine, there are the following problems during acceleration operation. In a diesel engine without a throttle valve, when the driver steps on the accelerator pedal, the amount of fuel injected into the combustion chamber increases, and the operation shifts from steady operation to accelerated operation. That is,
Unlike an intake pipe injection type gasoline engine or the like to which an air-fuel mixture having a predetermined air-fuel ratio is supplied, the fuel injection amount is increased irrespective of the intake air amount, whereby the generated torque is increased and acceleration is performed. Therefore, the excess air ratio in the combustion chamber is determined by the intake air amount and the fuel injection amount, and greatly fluctuates during the acceleration operation. In other words, at the very beginning of the acceleration operation, the excess air ratio decreases momentarily due to the increase in the fuel injection amount, but if the supercharging pressure by the turbocharger increases with the increase in the exhaust pressure, the air intake amount increases. The excess air ratio also increases rapidly. Therefore, when the entire period of the acceleration operation is considered, the increase of the harmful exhaust gas component is suppressed to a level that does not cause a problem.

However, in a turbocharged diesel engine equipped with an EGR device, the EGR from the exhaust system
Because gas is taken out from the upstream of the turbine,
When the EGR device is operating (when the EGR gas is recirculated), a non-negligible portion of the exhaust energy flows out to the intake system without driving the turbine. As a result, the rate of increase of the supercharging pressure also decreases, and due to the decrease of the excess air rate,
This has led to an increase in harmful emission components. Also, when the fuel injection amount is suppressed to prevent a decrease in the excess air ratio,
There was a problem that the acceleration force naturally declined and drivability deteriorated. Further, even when a known linear air-fuel ratio sensor or the like is used, it is almost impossible to appropriately control the fuel injection amount because it is difficult to detect the excess air ratio in real time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has a turbocharged system capable of achieving both the securing of acceleration force and the reduction of harmful exhaust gas components while adopting a relatively simple apparatus configuration. It is an object of the present invention to provide an excess air ratio control device for a motorized engine.

[0008]

SUMMARY OF THE INVENTION Accordingly, in a first aspect of the present invention, there is provided a turbocharger for driving a turbine by exhaust gas of an engine mounted on a vehicle to supercharge intake air to the engine. An exhaust gas recirculation device that recirculates a part of exhaust gas extracted from an exhaust passage on an upstream side of a turbocharger to an intake passage of the engine; an intake pressure detecting unit that detects intake pressure of the engine; Exhaust pressure detecting means for detecting the exhaust pressure of the exhaust gas, and exhaust gas recirculation by the exhaust gas recirculation device based on the intake pressure detected by the intake pressure detecting means and the exhaust pressure detected by the exhaust pressure detecting means. Exhaust gas recirculation amount estimating means for estimating a flow rate, intake air amount detecting means for detecting an intake air amount of the engine including an exhaust gas recirculation amount by the exhaust gas recirculation device, The engine based on the intake air amount detected by the intake air amount detecting means, the excess air ratio estimated a predetermined number of times earlier, and the exhaust gas recirculation amount estimated by the exhaust gas recirculation amount estimating means. Equivalent intake new air amount estimating means for estimating an equivalent intake new air amount; fuel supply amount setting means for setting a fuel supply amount of the engine according to an operation amount of an accelerator pedal of the vehicle; An excess air ratio estimating means for estimating the excess air ratio of the engine based on the fuel supply amount set by the above and the equivalent intake new air amount estimated by the equivalent new intake air amount estimating means; Fuel supply amount correction means for correcting the fuel supply amount set by the fuel supply amount setting means based on a comparison result between the excess air ratio estimated by the means and the predetermined excess air ratio; Based on the fuel supply amount corrected by the supply amount correcting means, it proposes an air excess ratio control apparatus for an engine with a turbocharger, characterized in that a fuel supply means for supplying fuel to the engine.

[0009] In a preferable embodiment, the at excess air ratio control apparatus according to claim 1, said intake air amount detecting means is for detecting the intake air amount based on the detected intake pressure by the intake pressure detecting means Is good . Further, in claim 2, in the excess air ratio control apparatus according to claim 1, said exhaust pressure detecting means obtains the exhaust pressure constant value from the engine speed and the fuel supply amount, and the exhaust gas pressure constant value, the number of each A turbine acceleration pressure is obtained from the exhaust gas recirculation amount and the intake air amount before the stroke, a load is obtained from the turbine acceleration pressure and the exhaust gas steady value, and the previous value of the exhaust pressure, the turbine acceleration pressure, and the load are obtained. From this, we propose a method to find the current value of the exhaust pressure.

[0010] In another preferred aspect , the present invention is directed to claim 1.
Or In 2 of the excess air ratio control apparatus, the exhaust gas recirculation quantity estimating means is good is intended to estimate the exhaust gas recirculation amount based on the opening degree of the exhaust gas recirculation device. According to a third aspect of the present invention, in the excess air ratio control device according to the first or second aspect , the exhaust gas recirculation amount estimating means obtains an orifice coefficient from a differential pressure between the exhaust pressure and the intake pressure to determine an engine rotational speed, a fuel Calculate the recirculated exhaust gas temperature coefficient from the supply amount, the valve opening degree of the exhaust gas recirculation device, the throttle coefficient of the exhaust gas recirculation device, the orifice coefficient,
A method for estimating the exhaust gas recirculation amount from the recirculated exhaust gas temperature coefficient is proposed.

According to a fourth aspect of the present invention , in the air excess ratio control device according to any one of the first to third aspects, the equivalent intake fresh air amount estimating means divides the recirculation amount of the exhaust gas from the intake air amount by the excess air ratio. Is proposed to estimate the equivalent intake fresh air volume by reducing the calculated value. In a preferable embodiment, the excess air ratio control apparatus according to claim 1-4, it is preferable in the fuel supply means is for injecting fuel directly into a combustion chamber of the engine.

According to another preferred aspect, the present invention is characterized in that:
In the excess air ratio control apparatus 1-4, the excess air rate estimating means, it is preferable to estimate the excess air ratio is performed for every one stroke of the engine. Further , a more preferred embodiment
In the excess air ratio control device according to claims 1 to 4 ,
The fuel supply amount correcting means, as the excess air rate estimated by said excess air rate estimating means approaches the predetermined excess air rate, and even as to correct the fuel supply amount
Good .

In a further preferred aspect , in the excess air ratio control device according to any one of claims 1 to 4 , the fuel supply amount correction means includes a predetermined excess air ratio based on the excess air ratio estimated by the excess air ratio estimation means. when the larger, better to those to reduce the fuel supply amount.
Further , as a further preferred aspect , in the excess air ratio control device according to any one of claims 1 to 4 , the fuel supply amount correction means includes:
When the predetermined excess air ratio is larger than the excess air ratio estimated by the excess air ratio estimating means, the correction is performed by multiplying the fuel supply amount by the excess air ratio and dividing by the predetermined excess air ratio. Is to do
No.

According to a fifth aspect of the present invention , in the air excess ratio control device of the first to fourth aspects, the predetermined excess air ratio is a preset target excess air ratio, and is estimated by the excess air ratio estimation means. It is proposed to further provide an exhaust gas recirculation control means for driving and controlling the exhaust gas recirculation device based on a deviation between the excess air ratio and the target excess air ratio.

[0015] In a preferable embodiment, the excess air ratio control apparatus according to claim 5, the target excess air ratio is set based on the engine rotational speed fuel supply amount set by said fuel supply quantity setting means Is good . As another preferred embodiment , in the air excess ratio control device according to claim 5 , the exhaust gas recirculation control means is configured to control the exhaust gas recirculation when the target air excess ratio is larger than the air excess ratio. device may be from one that drives and controls the closing direction.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an excess air ratio control device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an engine control system to which an EGR device is attached. In FIG. 1, reference numeral 1 denotes an in-line four-cylinder diesel engine (hereinafter simply referred to as engine) for an automobile. 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.
The fuel is supplied to each fuel injection nozzle 4 via the. still,
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 figure, 9 is a water temperature sensor attached to the cylinder head 2 for detecting the cooling water temperature Tw, and 10 is a Ne sensor attached to the fuel injection pump 6 for detecting the 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 engine 14. 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 pressure (Manifold Absolute).
Pressure) is a boost pressure sensor that detects Pb, and both 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 intake manifold 11 communicate with each other via an EGR pipe 30, and the pipeline of the EGR pipe 30 is connected to the intake manifold 1
Opened by the valve element 32 of the EGR valve 31 provided on the first side.
It is designed to be shut 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, 36 is EG
An EGR position sensor that detects the opening A _E of the R 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 _AE 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.) for storing a control program, a central processing unit (CPU), and the like. 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 starts the electronic governor 5 and the other ECUs.
The drive control of the GR solenoids 42 and 45 is performed.

The control procedure of the excess air ratio in the present embodiment will be described below. Driver turns on ignition key
The engine 1 is started under predetermined conditions (in the case of the present embodiment, the water temperature TW is 70 ° C. or more, 30 seconds or more have elapsed after the start, the boost pressure sensor 17 and the EGR position sensor 3
6 is normal, etc.), the ECU 8
The excess air ratio control subroutine shown in the flowcharts of FIGS. 2 to 4 is repeatedly executed for each stroke of the engine 1. When this subroutine is started, the ECU 8 firstly executes the electronic governor 5 and the Ne sensor 10 in step S2 in FIG.
The accelerator instruction fuel amount QFacc (cc / st) is retrieved from the map shown in FIG. 5 on the basis of the accelerator opening information θacc (%) and the engine rotation speed Ne (rpm) output from.

Next, in step S4, the ECU 8 extracts the current total intake air amount QIN (i) (g) to be sucked into the engine 1 based on the outputs of the intake air temperature sensor 16, the boost pressure sensor 17, and the like.
/ st) is calculated by the following equation. In the following equation, Pb is the intake pipe pressure (mmH ₂ O), V is the displacement (l) per cylinder, and KvE is a map (not shown) based on the engine speed Ne (rpm) and the intake pipe pressure Pb. Is a volume efficiency correction coefficient obtained from the following equation, and Ta is an intake air temperature (° C.). QIN (i) = (Pb / 760) · V · KvE · 1.2 · (293 / (273 + T
a)) Next, in step S6, the ECU 8 retrieves a turbine upstream pressure steady-state value PTo from a map (not shown) based on the engine rotation speed Ne and the accelerator instruction fuel amount QFacc. Turbine upstream pressure P
Calculate T (i).

In calculating the turbine upstream pressure PT (i), the ECU 8 firstly calculates the turbine acceleration pressure PA by the following equation.
Is calculated. In the following equation, QE (i-3) and QIN (i-3) are the EGR amount and the total intake amount three strokes ago, respectively. PA = PTo８ (1−QE (i−3) / QIN (i−3)) Next, the ECU 8 calculates the load PL from the turbine acceleration pressure PA and the turbine upstream pressure steady value PTo by the following equation.

[0024] PL = PA ² / PTO Finally, ECU 8 uses the the previous value PT (i-1) and turbine acceleration pressure PA and the load PL, turbine upstream pressure PT (i)
Is calculated by the following equation. In the following equation, IT is a turbine inertia coefficient. PT (i) = PT (i-1) + (PA-PL) / IT In this way, when the turbine upstream pressure PT (i) is obtained,
The ECU 8 determines in step S10 that the current EGR amount QE (i)
(G / st) is calculated by the following equation. Where AE is EG
EGR valve 31 detected by R position sensor 36
, Ks is a throttle coefficient (constant value), and Ko is an orifice coefficient retrieved from a map (not shown) based on a pressure difference ΔP between the turbine upstream pressure PT (i) and the intake pipe pressure Pb. KET is an EGR temperature coefficient retrieved from a map (not shown) based on the engine speed Ne and the accelerator instruction fuel amount QFacc.

QE (i) = AE · Ks · Ko · KET · 60 / (2 · Ne) When the EGR amount QE (i) is obtained, the ECU 8 then updates the total intake air amount QIN (i) in step S12. Calculate the equivalent intake fresh air amount Qa (i) converted to air. Here, λ (i-3) is the estimated excess air ratio three strokes before, and is 2% from the start of the subroutine.
The value is set to a predetermined value (for example, 1.2) until the second processing (that is, the second stroke).

Qa (i) = QIN (i) -QE (i) / λ (i-3) Next, the ECU 8 calculates the equivalent intake fresh air amount Qa (i) thus obtained and the accelerator instruction fuel. In step S14, the current estimated excess air ratio λ (i) is calculated from the amount QFacc.
Here, 14.5 is the stoichiometric air-fuel ratio of the diesel engine. λ (i) = Qa (i) / (QFacc · 14.5) Next, in step S16 of FIG. 3, the ECU 8 determines that the current estimated excess air ratio λ (i) is , 1.5) is determined. If this determination is No due to an increase in the accelerator instruction fuel amount QFacc during acceleration, the ECU 8 calculates the current target fuel injection amount QFT (i) in step S18 by the following equation. When fuel injection is performed based on the target fuel injection amount QFT (i), the actual excess air ratio λ becomes equal to the excess air ratio lower limit λlim, and an increase in harmful exhaust gas components is prevented.

QFT (i) = QFacc · (λ (i) / λlim) Also, the estimated excess air ratio λ (i) is sufficiently large, and
If the determination in step 16 is Yes, the ECU 8 sets the accelerator instruction fuel amount QFacc as it is as the current target fuel injection amount QFT (i) in step S20. When the current target fuel injection amount QFT (i) is determined in step S18 or step S20, the ECU 8 then determines in step S22 a map (not shown) based on the engine speed Ne and the accelerator instruction fuel amount QFacc previously determined. The target excess air ratio λtarget is searched.

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. Here, the target excess air ratio λ
Since both the target and the estimated excess air ratio λ (i) are obtained based on the accelerator instruction fuel amount QFacc, step S
Even when the target fuel injection amount QFT (i) has been reduced at 18, the deviation Δλ has a relatively large value.

Δλ = λtarget−λ (i) After calculating the deviation Δλ, the ECU 8 proceeds to step S2.
In step 6, using a predetermined proportional gain KP,
The proportional term EPP of the R control is calculated. EPP = KP · Δλ Next, in step S28, if the deviation Δλ is between the upper limit value λU and the lower limit value λL, the ECU 8 sets the proportional gain KI to a predetermined value, while the deviation Δλ is out of the range. If so, the proportional gain KI is set to 0, and in step S30, the integral term EPI of the EGR control is calculated by the following equation. This is because, when the deviation is larger than the upper limit value λU or smaller than the lower limit value λL, the absolute value of the integral term EPI becomes too large, and the control followability to the change of the operating state is deteriorated.

EPI = EPI + KI ・ Δλ When the calculation of the proportional term EPP and the integral term EPI is completed, the ECU 8
Calculates the basic correction amount EP of the EGR valve opening in step S32 in FIG. EP = EPP + EPI Next, in step S34, the ECU 8 performs a limiter process of clipping the calculated basic correction amount EP at predetermined upper and lower limits, and sets the opening correction amount Eposc of the EGR valve 31.

Next, in step S36, the ECU 8 retrieves a target opening Eo of the EGR valve 31 from a map (not shown) based on the engine speed Ne and the target fuel injection amount QFT (i). Then, the target EGR valve opening Epos is calculated. Epos = Eo + Eposc Next, the ECU 8 determines in step S40 that the target fuel injection amount Q
Drive control of the electronic governor 5 is performed based on FT (i), and EGR is performed based on the target EGR valve opening Epos in step S42.
After the drive control of the valve 31, the process returns to the start and the control is repeated.

As described above, in the present embodiment, the fuel injection control is performed so as to clip the actual excess air ratio λ at the lower limit value. The generated torque of the engine 1 could be increased to the limit. On the other hand, the introduction control of the EGR gas is performed by controlling the target excess air ratio λtarget and the accelerator instruction fuel amount Q.
Since the adjustment is performed in accordance with the deviation Δλ from the estimated excess air ratio λ (i) obtained from Facc, the EGR valve 3 during acceleration or the like is used.
1 was compensated for, and a decrease in the supercharging pressure due to the outflow of the exhaust pressure to the intake system could be reduced.

The description of the specific embodiment has been completed.
The present invention is not limited to this embodiment. For example, in the above-described embodiment, the present invention is applied to a diesel engine provided with a turbocharger, but is also suitable for a lean-burn gasoline engine or the like. Further, in the above-described embodiment, the fuel injection amount before the third stroke is used as the transfer delay fuel injection amount, but a variable method using the fuel injection amount before the second stroke or after the fourth stroke according to the operating state or the like may be adopted. Good.
In the above embodiment, the excess air ratio is estimated for each intake stroke. However, the estimation may be performed asynchronously with the stroke. The specific configuration and control procedure of the engine control system can be changed without departing from the gist of the present invention.

[0034]

According to the first aspect of the present invention, there is provided a turbocharger for driving a turbine by exhaust gas of an engine mounted on a vehicle to supercharge intake air to the engine. An exhaust gas recirculation device that recirculates a part of the exhaust gas extracted from an exhaust passage on the upstream side of the supercharger to an intake passage of the engine; an intake pressure detecting unit that detects an intake pressure of the engine; Exhaust pressure detecting means for detecting exhaust pressure; and the amount of exhaust gas recirculated by the exhaust gas recirculation device based on the intake pressure detected by the intake pressure detecting means and the exhaust pressure detected by the exhaust pressure detecting means. Exhaust gas recirculation amount estimation means for estimating the intake air amount, intake air amount detection means for detecting the intake air amount of the engine including the exhaust gas recirculation amount by the exhaust gas recirculation device, An intake amount detected by the amount detecting means, and the excess air rate estimated before a predetermined number of times,
An equivalent intake fresh air amount estimating means for estimating an 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 an operation amount of an accelerator pedal of the vehicle; Fuel supply amount setting means for setting the fuel supply amount of the engine, and the fuel supply amount set by the fuel supply amount setting means and the equivalent intake fresh air amount estimated by the equivalent intake new air amount estimation means. Based on
The excess air ratio estimating means for estimating the excess air ratio of the engine and the fuel supply amount setting means set based on a comparison result between the excess air ratio estimated by the excess air ratio estimating means and a predetermined excess air ratio. A fuel supply amount correcting unit that corrects a fuel supply amount to be supplied, and a fuel supply unit that supplies fuel to the engine based on the fuel supply amount corrected by the fuel supply amount correcting unit. If the excess air ratio becomes lower than the predetermined excess air ratio, by correcting the fuel supply amount so that the actual excess air ratio becomes equal to the predetermined excess air ratio,
The reduction of the acceleration power can be minimized while preventing the emission of harmful exhaust gas components.

Further, good air excess ratio control apparatus 請 Motomeko 1
As a preferred embodiment , the intake air amount detecting means preferably detects the intake air amount based on the intake air pressure detected by the intake air pressure detecting means, so that it is not necessary to provide an expensive air flow sensor or the like. . According to a second aspect of the present invention, in the excess air ratio control device according to the first aspect , the exhaust pressure detecting means obtains a steady-state exhaust pressure value from the engine rotation speed and the fuel supply amount. The turbine acceleration pressure is obtained from the exhaust gas recirculation amount and the intake amount several strokes ago, the load is obtained from the turbine acceleration pressure and the exhaust pressure steady value, and the previous value of the exhaust pressure, the turbine acceleration pressure, Since the present value of the exhaust pressure is obtained from the above load, it is not necessary to provide an exhaust pressure sensor, thereby suppressing an increase in cost, the number of parts, and the like.

Further, as another preferred embodiment of the excess air ratio control apparatus 請 Motomeko 1 or 2, the exhaust gas recirculation quantity estimating means estimates the exhaust gas recirculation amount based on the opening degree of the exhaust gas recirculation system Should be done, so that
There is no need to provide a flow sensor or the like for the recirculated exhaust gas, and increases in cost, number of parts, etc. can be suppressed. According to a third aspect , in the excess air ratio control device according to the first or second aspect , the exhaust gas recirculation amount estimating means obtains an orifice coefficient from a differential pressure between the exhaust pressure and the intake pressure, and determines an orifice coefficient according to the engine rotational speed. Calculate the recirculation exhaust gas temperature coefficient from the fuel supply amount, and calculate the recirculation exhaust gas temperature coefficient from the valve opening degree of the exhaust gas recirculation device, the throttle coefficient of the exhaust gas recirculation device, the orifice coefficient, and the recirculation exhaust gas temperature coefficient. Since the exhaust gas recirculation amount is estimated, it is not necessary to provide a flow sensor for the recirculated exhaust gas or the like, thereby suppressing an increase in cost, the number of parts, and the like.

According to a fourth aspect of the present invention, in the excess air ratio control device according to any one of the first to third aspects, the equivalent intake fresh air amount estimating means determines the recirculation amount of the exhaust gas from the intake air amount by the excess air ratio. By reducing the value divided by the above, the equivalent intake new air amount is estimated, so that the equivalent intake new air amount can be estimated accurately and in real time. In a preferable embodiment of the excess air ratio control apparatus 請 Motomeko 1-4,
It is preferable that the fuel supply means injects fuel directly into the combustion chamber of the engine , so that even when the engine is a diesel engine or the like, a decrease in the excess air ratio can be suppressed.

Further, the excess air ratio control apparatus 請 Motomeko 1-4
In another preferred embodiment , the excess air ratio estimating means preferably performs the estimation of the excess air ratio for each stroke of the engine , so that the control responsiveness such as the fuel injection amount and the EGR amount is improved. improves. Moreover, a further preferred embodiment of the excess air ratio control apparatus 請 Motomeko 1-4, the fuel supply amount correcting means, so that the excess air rate estimated by said excess air rate estimating means approaches the predetermined excess air rate In addition, it is better to correct the above-mentioned fuel supply amount.
As a result, an increase in harmful exhaust gas components due to a decrease in the excess air ratio can be suppressed.

Further, the excess air ratio control apparatus 請 Motomeko 1-4
As a further preferred aspect, the fuel supply amount correcting means, when towards the predetermined excess air ratio is larger than the excess air rate estimated by said excess air rate estimating means, so as to reduce the fuel supply amount It is good
Thus, an increase in harmful exhaust gas components due to a decrease in the excess air ratio can be suppressed.

Further, the excess air ratio control apparatus 請 Motomeko 1-4
As a further preferred aspect of the present invention , the fuel supply amount correcting means, when the excess air rate is larger than the excess air rate estimated by the excess air rate estimating means, the excess air rate to the fuel supply amount with multiplying, that to perform the correction by dividing in the predetermined excess air rate
In this way, it is possible to control the fuel supply limit while suppressing the emission of harmful exhaust gas components.

According to a fifth aspect of the present invention, in the air excess ratio control device according to any one of the first to fourth aspects, the predetermined excess air ratio is a preset target excess air ratio, and the predetermined excess air ratio is determined by the excess air ratio estimation means. Exhaust gas recirculation control means for driving and controlling the exhaust gas recirculation device based on the difference between the estimated excess air ratio and the target excess air ratio is further provided, so that the exhaust gas pressure is caused to flow out to the intake system. The decrease of the supercharging pressure can be reduced.

Further, good air excess ratio control apparatus 請 Motomeko 5
As preferable embodiments, the target excess air ratio is to to be set based on the engine rotational speed fuel supply amount set by said fuel supply quantity setting means well, this
Thereby, the operation delay of the exhaust gas recirculation device at the time of acceleration or the like is compensated. Further, the excess air ratio control apparatus 請 Motomeko 5
As another preferred embodiment , the exhaust gas recirculation control means controls the drive of the exhaust gas recirculation device in a closing direction when the target excess air ratio is larger than the excess air ratio . Therefore, the operation delay of the turbocharger due to the outflow of the exhaust pressure to the intake system is reduced, and the emission of the harmful exhaust gas component due to the decrease in the excess air ratio is suppressed.

[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 showing a procedure of an excess air ratio control subroutine.

FIG. 3 is a flowchart illustrating a procedure of an excess air ratio control subroutine.

FIG. 4 is a flowchart illustrating a procedure of an excess air ratio control subroutine.

FIG. 5 is a map for obtaining an accelerator instruction fuel amount from an accelerator opening and an engine rotation speed.

[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 20 Exhaust manifold 21 Turbine 30 EGR pipe 31 EGR valve 42 Negative pressure side EGR solenoid 43 Vacuum Pump 45 Atmospheric EGR solenoid

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 41/18 F02D 41/18 Z 45/00 366 45/00 366E F02M 25/07 550 F02M 25/07 550R 570 570P (56) References JP-A-6-26383 (JP, A) JP-A-1-271622 (JP, A) JP-A-63-176647 (JP, A) JP-A-61-207856 (JP, A) JP-A-4 JP-A-203453 (JP, A) JP-A-1-290940 (JP, A) JP-A-7-151007 (JP, A) JP-A-61-160259 (JP, U) (58) Fields investigated (Int. . ^7, DB name) F02D 41/02 380 F02D 21/08 301 F02D 23/02 F02D 41/18

Claims (5)

(57) [Claims] 1. A turbocharger for driving a turbine by exhaust gas of an engine mounted on a vehicle to supercharge intake air to the engine, and exhaust gas extracted from an exhaust passage on an upstream side of the turbocharger. An exhaust gas recirculation device that recirculates a part of gas to an intake passage of the engine; an intake pressure detecting unit that detects an intake pressure of the engine; an exhaust pressure detecting unit that detects an exhaust pressure of the engine; Exhaust gas recirculation amount estimating means for estimating the amount of exhaust gas recirculated by the exhaust gas recirculation device based on the intake pressure detected by the pressure detecting means and the exhaust pressure detected by the exhaust pressure detecting means; Intake air amount detection means for detecting an intake air amount of the engine including an exhaust gas recirculation amount by a gas recirculation device; and an intake air amount detected by the intake air amount detection means And an equivalent intake new air amount for estimating an equivalent intake fresh air amount of the engine based on the excess air ratio estimated a predetermined number of times ago and the exhaust gas recirculation amount estimated by the exhaust gas recirculation amount estimating means. Air amount estimating means; fuel supply amount setting means for setting the fuel supply amount of the engine according to the operation amount of an accelerator pedal of the vehicle; fuel supply amount set by the fuel supply amount setting means and the equivalent suction Excess air ratio estimating means for estimating the excess air ratio of the engine based on the equivalent intake fresh air amount estimated by the fresh air amount estimating means, and an excess air ratio estimated by the excess air ratio estimating means and the predetermined air A fuel supply amount correcting means for correcting the fuel supply amount set by the fuel supply amount setting means based on a comparison result with the excess rate; and a fuel supply amount corrected by the fuel supply amount correcting means. And a fuel supply means for supplying fuel to the engine based on a supply amount. 2. The exhaust pressure detecting means calculates a steady-state exhaust pressure value from an engine speed and a fuel supply amount. Determining an acceleration pressure, obtaining a load from the turbine acceleration pressure and the exhaust gas steady-state value, and obtaining a current value of the exhaust pressure from the previous value of the exhaust pressure, the turbine acceleration pressure, and the load. to, the excess air ratio control apparatus according to claim 1 Symbol placement engine with turbocharger. 3. The exhaust gas recirculation amount estimating means obtains an orifice coefficient from a differential pressure between the exhaust pressure and the intake pressure, and obtains a recirculation exhaust gas temperature coefficient from an engine speed and a fuel supply amount. and valve opening of the recirculation device, the restriction factor of the exhaust gas recirculation device, and the orifice coefficient, and estimates the exhaust gas recirculation amount from the above recirculated exhaust gas temperature coefficient, claim 1 or 3. An excess air ratio control device for an engine with a turbocharger according to 2 . 4. An equivalent intake fresh air amount estimating means for estimating an equivalent intake fresh air amount by subtracting a value obtained by dividing a recirculation amount of the exhaust gas by the excess air ratio from the intake air amount. The excess air ratio control device for an engine with a turbocharger according to any one of claims 1 to 3 . 5. The exhaust gas control device according to claim 1, wherein the predetermined excess air ratio is a preset target excess air ratio, and the exhaust gas is determined based on a deviation between the excess air ratio estimated by the excess air ratio estimation means and the target excess air ratio. The apparatus for controlling an excess air ratio of an engine with a turbocharger according to any one of claims 1 to 4 , further comprising exhaust gas recirculation control means for controlling driving of the recirculation apparatus.