JP3161291B2 - 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 operated (when EGR gas is recirculated), a non-negligible portion of the increased exhaust pressure flows out to the intake system. As a result, the rate of increase of the supercharging pressure is also small, and the harmful exhaust gas component is increased due to the decrease of the excess air rate. Further, when the fuel injection amount is unconditionally suppressed in order to prevent a decrease in the excess air ratio, the acceleration force naturally decreases and drivability deteriorates. 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; A fuel supply unit for supplying fuel to the engine based on the fuel supply amount set by the fuel supply amount setting unit, and a fuel supply amount set by the fuel supply amount setting unit and an equivalent intake estimated by the equivalent intake fresh air amount estimation unit. The excess air ratio estimating means for estimating the excess air ratio of the engine based on the fresh air amount and the excess air ratio estimated by the excess air ratio estimating means are within a predetermined allowable range. Determining means for determining whether or not the excess air ratio is out of the allowable range; andexhaust gas recirculation control means for driving the exhaust gas recirculation device in a closing direction when the determining means determines that the excess air ratio is outside the allowable range. We propose a system for controlling the excess air ratio of an engine with a turbocharger.

According to a second aspect of the present invention, in the first aspect, the fuel supply means injects fuel directly into a combustion chamber of the engine. According to a third aspect of the present invention, in the excess air ratio control device of the first or second aspect, the equivalent intake fresh air amount estimating means calculates a value obtained by dividing the recirculation amount of the exhaust gas by the excess air ratio from the intake air amount. We propose a method of estimating the equivalent intake fresh air volume by reducing it.

In a preferred embodiment , claims 1 to 3 are provided.
In the excess air ratio control apparatus, the excess air rate estimating means, it is preferable to estimate the excess air ratio for each one stroke of the engine. According to a fourth aspect , in the excess air ratio control device according to the first to third aspects, when the determination unit determines that the excess air ratio is out of the allowable range, regardless of the operation amount of the accelerator pedal, It is proposed to further provide a suppression means for suppressing the increase in the fuel supply amount.

In a preferred aspect , in the air excess ratio control device according to claim 4 , the suppression means performs the suppression by holding the fuel supply amount at a previous value.
Is good . In another preferred embodiment , in the air excess ratio control device according to claim 4 , the suppression means cancels the suppression after a predetermined time has elapsed since the driving of the exhaust gas recirculation device in the closing direction was started. Good to do .

[0012] Further , as a further preferred embodiment ,
In the excess air ratio control device of 4, the suppression means preferably releases the suppression when the determination means determines that the excess air ratio has returned to the allowable range.

[0013]

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 interface. 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 are communicated via an EGR pipe 30, and the pipe 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.

Hereinafter, a control procedure of the excess air ratio in the present embodiment will be described. 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 based on the outputs of the intake air temperature sensor 16, the boost pressure sensor 17, etc., extracts the total intake air amount QIN (i) (g
/ st) is calculated by the following equation. In the following equation, Pb is the intake pipe pressure (mmHg), V is the displacement (l) per cylinder, and KvE is obtained from a map (not shown) based on the engine speed Ne (rpm) and the intake pipe pressure Pb. 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 first 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.

[0021] 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) obtained in this manner 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 the determination is No due to an increase in the accelerator instruction fuel amount QFacc during acceleration, the ECU 8 outputs a command to close the EGR valve 31 in step S18. In addition, the negative pressure is introduced into the negative pressure chamber 35 of the EGR valve 31 by the closing command, and the valve body 32 is driven in the closing direction. However, it takes a predetermined time until the valve body 32 is completely closed. The introduction will be stopped gradually.

When a closing command is output in step S18,
Next, the ECU 8 determines whether or not the timer set completion flag Fts is 1 in step S20. The timer set flag Fts is a flag indicating whether or not a fuel limit timer Tfc to be described later has been activated.
It has been reset to 0 at the time of setting to N. Step S2
Since the first determination of 0 is No, the ECU 8 activates a fuel restriction timer Tfc that measures the fuel restriction period in step S22, and then sets the timer set flag Fts to 1 in step S24. Next, the ECU 8 determines in step S26 whether or not the value of the fuel limit timer Tfc has exceeded the predetermined time T1. If this determination is No, the current fuel injection amount QFI (i) is determined in step S28 in FIG. Previous value Q
After being held in FI (i-1), the electronic governor 5 is set in step S30.
Is driven to perform fuel injection. As a result, the excess air ratio λ is maintained as it is, and an increase in harmful exhaust gas components is prevented.

If the value of the fuel limit timer Tfc exceeds the predetermined time T1 and the determination in step S26 becomes Yes, the ECU 8
Sets the accelerator instruction fuel amount QFacc described above in step S32 of FIG. 4 to the current fuel injection amount QFI (i). Next, E
After stopping the accumulation of the fuel limit timer Tfc in step S34, the CU 8 controls the drive of the electronic governor 5 to perform fuel injection in step S30. The predetermined time T1 is set to a value sufficient for the EGR valve 31 to be fully closed. At this point, the exhaust pressure does not flow to the intake system, and the supercharging pressure rises in a very short time. Therefore, the generated torque increases due to the increase in the fuel injection amount, the acceleration intended by the driver is performed, and the excess air ratio λ
Does not decrease significantly, and the increase in harmful exhaust gas components is suppressed to a level that does not cause a problem.

On the other hand, if the estimated excess air ratio λ (i) increases due to an increase in the intake air amount and the like, and the determination in step S16 becomes Yes, the ECU 8 controls the drive control of the EGR valve 31 in step S36 in FIG. After returning to the state, the accelerator instruction fuel amount QFacc is set to the current fuel injection amount QFI (i) in step S38. Next, after resetting the timer set flag Fts to 0 in step S40, the ECU 8 controls the drive of the electronic governor 5 to perform fuel injection in step S30. Thus, it aimed at the reduction of improving the NO _X output and fuel consumption, so that normal control of fuel injection and the EGR control is performed.

As described above, in the above embodiment, the fuel injection amount is limited and the introduction of EGR gas is stopped in accordance with the decrease in the excess air ratio. It has become possible to suppress the increase. This concludes the description of the specific embodiment, but the present invention is not limited to this embodiment. For example, in the above embodiment, when the excess air ratio is out of a predetermined range, the EGR
Although the valve is fully closed, the opening may be suppressed to, for example, about 50%. Further, in the above embodiment, the fuel injection amount is switched to the accelerator instruction fuel amount at a time after a predetermined time has elapsed after the estimated excess air ratio has fallen below the lower limit of the excess air ratio, but this switching is performed gradually. You may do so. The specific configuration and control procedure of the engine control system can be changed without departing from the gist of the present invention.

[0028]

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, fuel supply means for supplying fuel to the engine based on the fuel supply amount set by the fuel supply amount setting means, Means for estimating an excess air ratio of the engine based on the fuel supply amount set by the means and the equivalent intake fresh air amount estimated by the equivalent intake fresh air amount estimation means; Determining means for determining whether or not the excess air rate estimated by the estimation means is within a predetermined allowable range; and determining that the excess air rate is out of the allowable range by the determining means. The exhaust gas recirculation device is provided with exhaust gas recirculation control means for driving the exhaust gas recirculation device in the closing direction, thereby eliminating the operation delay of the turbocharger due to the exhaust pressure flowing out to the intake system, and Even when the fuel supply amount increases at times, the excess air ratio is less likely to decrease. As a result, it is possible to reduce harmful exhaust gas components while minimizing a decrease in acceleration force.

According to the excess air ratio control device of the second aspect, in the excess air ratio control device of the first aspect, the fuel supply means injects fuel directly into the combustion chamber of the engine. Is a diesel engine or the like, the reduction of the excess air ratio can be suppressed. According to the excess air ratio control device of the third aspect,
3. The air intake ratio control device according to claim 1, wherein the equivalent intake fresh air amount estimating means subtracts a value obtained by dividing a recirculation amount of the exhaust gas by the air excess ratio from the intake air amount. Since the amount is estimated, the excess air ratio during transient operation or the like can be accurately detected without using a linear air-fuel ratio sensor or the like that is inferior in reliability and responsiveness.

Further, the excess air ratio control apparatus 請 Motomeko 1-3
As a preferred embodiment, the excess air rate estimating means is for performing estimation excess air ratio for each one stroke of the engine
Preferably, this improves the control responsiveness of the fuel injection amount, EGR amount, and the like. According to the fourth aspect , in the excess air ratio control device according to any one of the first to third aspects, when the determination means determines that the excess air ratio is out of the allowable range, the controller determines whether or not the accelerator pedal is operated. In addition, since the fuel cell system further includes a suppression unit that suppresses an increase in the fuel supply amount, even if there is a delay in closing the exhaust gas recirculation device, a decrease in the excess air ratio can be prevented.

Further, good air excess ratio control apparatus 請 Motomeko 4
As preferable embodiments, the suppression means, der performs the inhibition by holding the fuel supply amount to the previous value
Preferably, this simplifies the processing required to control the fuel supply. Further, the excess air ratio control apparatus 請 Motomeko 4
In another preferred embodiment , the suppression means cancels the suppression after a lapse of a predetermined time from the start of the drive of the exhaust gas recirculation device in the closing direction .
As a result, the acceleration response does not deteriorate more than necessary.

Further, the excess air ratio control apparatus 請 Motomeko 4
As a more preferable aspect , the suppression means may release the suppression when the determination means determines that the excess air ratio has returned to the allowable range .
As a result, the acceleration response does not deteriorate more than necessary.

[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 -203453 (JP, A) JP-A-1-290940 (JP, A) JP-A-8-303278 (JP, A) JP-A-61-160259 (JP, U) (58) Fields investigated (Int. . ^7, DB name) F02D 21/08 301 F02B 37/00 302 F02D 23/00 F02D 41/02 380 F02D 41/18 F02M 25/07 550 F02M 25/07 570

Claims (4)

(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 quantity 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, and a fuel supply amount set by the fuel supply amount setting means. A fuel supply means for supplying fuel to the engine; and an air supply of the engine based on the fuel supply amount set by the fuel supply amount setting means and the equivalent intake fresh air amount estimated by the equivalent intake fresh air amount estimation means. Excess air rate estimating means for estimating an excess rate, determining means for determining whether or not the excess air rate estimated by the excess air rate estimating means is within a predetermined allowable range; And an exhaust gas recirculation control means for driving the exhaust gas recirculation device in a closing direction when it is determined that the excess air ratio is out of the allowable range. Excess air ratio control device. 2. The control device according to claim 1, wherein said fuel supply means injects fuel directly into a combustion chamber of said engine. 3. 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 control device for an excess air ratio of an engine with a turbocharger according to claim 1 or 2, wherein: 4. The fuel cell system according to claim 1, further comprising a suppression unit that suppresses an increase in the fuel supply amount regardless of an operation amount of the accelerator pedal when the determination unit determines that the excess air ratio is out of the allowable range. 2. The method of claim 1, wherein
4. The control device for an excess air ratio of a turbocharged engine according to any one of claims 1 to 3 .