JP3141563B2 - Air flow control device for internal combustion 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 apparatus for controlling an intake air amount of an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in order to improve exhaust emissions of an internal combustion engine, a three-way catalyst is installed in an exhaust system, and H
It is known that the oxidation of C and CO and the reduction of NO are performed at the same time. However, such a catalyst can maintain the desired exhaust gas purification efficiency only in an active state at a predetermined temperature or higher. For this reason, exhaust emissions increase until the catalyst temperature rises, such as during a cold start of the engine.If the engine cooling water temperature is low, the exhaust temperature is raised by retarding the ignition timing to increase the exhaust temperature. It is trying to recover the function of the catalyst early.

For example, in Japanese Utility Model Laid-Open Publication No. 57-75173, in order to realize early warm-up of the catalyst when the engine is cold without impairing the operability, a switching valve operated according to the temperature of the engine cooling water is provided. A negative pressure generated in the vicinity of the intake throttle valve is selectively introduced into the negative pressure advance chamber of the distributor, and the ignition timing is retarded from a normal state in a cold state.

[0004]

However, if the ignition timing is retarded for warming up the catalyst as described above, the output torque decreases, and the engine speed tends to fluctuate unstablely in idling operation.

[0005] In addition, during traveling, the output (torque) characteristics of the engine with respect to the accelerator opening at the time of retarding and at the time of non-retarding differ, resulting in an uncomfortable driving feeling. Further, due to the power performance, there is also an operation region in which the retarding cannot be performed. When the vehicle shifts to the non-retarding region during traveling, a torque change accompanying switching (advance) of the ignition timing occurs, and deterioration of the operation performance is avoided. Absent.

According to the present invention, when the ignition timing is retarded for early activation of the catalyst, the amount of intake air is increased and corrected in accordance with the amount of retardation so as to prevent uncomfortable driving performance and torque fluctuation. It is an object of the present invention to provide an air amount control device for an internal combustion engine that has been described.

[0007]

According to the present invention , as shown in FIG. 1, means 1 for calculating a basic ignition timing from operating conditions,
Similarly, means 2 for calculating an ignition timing retard amount necessary for activation of the catalyst from operating conditions, means 3 for outputting an ignition signal obtained by correcting the basic ignition timing according to the retard amount, and an idle state. Means for determining whether or not the ignition timing
The amount of retard is the amount of retard when idling and the amount of retard when not idling.
Angular amount is set separately and the ignition timing is retarded
Amount and intake air amount or the intake air
Means for calculating the increase correction amount and air amount control means 5 for increasing the intake air amount in accordance with the increase correction amount are provided.

Further, as shown in FIG. 2, the present invention comprises a means 1 for calculating a basic ignition timing from operating conditions, a means 2 for calculating an ignition timing retard amount necessary for activation of the catalyst from operating conditions, Means 3 for outputting an ignition signal obtained by correcting the basic ignition timing in accordance with the retardation amount, and an increase correction amount of the intake air in accordance with the retardation amount of the ignition timing and the intake air amount or the throttle opening signal. It comprises a calculating means 4, a delay compensating means 6 for correcting the increase correction amount according to the intake manifold volume and the engine load, and an air amount control means 5 for increasing the intake air amount according to the correction amount.

[0009]

The ignition timing is controlled to be retarded when the engine is started at a low temperature, so that the exhaust gas temperature rises and the warming-up of the catalyst is promoted.

At the same time, the ignition timing retard amount is changed to the idle state.
Is set separately for the amount of retard at the time of
And the ignition timing retard amount and intake air amount or throttle
The intake air amount is increased and corrected in accordance with the valve opening signal, and the generated torque of the engine is maintained the same as when the ignition timing is not retarded.
Therefore, despite retarding the ignition timing,
The driving performance is the same as that of the normal operation, and no torque step occurs even if the ignition timing retard amount is switched depending on the operation region.

[0011] Further, by compensating the increase in the amount of delay, the intake air is not delayed when the amount of increase is increased, and more stable torque control is realized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 3, 11 is an engine body, 12 is an intake passage, 13 is an exhaust passage, 14 is an intake valve, and 15 is an exhaust valve. A three-way catalyst 16 is provided in the exhaust passage 13 to oxidize HC and CO in the exhaust gas and reduce NO.

Reference numeral 17 denotes a fuel injection valve for injecting fuel into the intake passage 12, and reference numeral 18 denotes an ignition plug for igniting a mixture in a combustion chamber 19.

A control device 21 is provided for controlling the amount of fuel injected from the fuel injection valve 17 and for controlling the ignition timing of an ignition device 20 for igniting the ignition plug 18.

In order to maintain the conversion efficiency of the three-way catalyst 16 to the maximum, the control device 21 adjusts the amount of intake air detected by the air flow sensor 22 so that the fuel injected from the fuel injection valve 17 has the stoichiometric air-fuel ratio. The fuel injection amount is calculated according to the engine speed detected by the speed sensor 23.

The controller 21 calculates the ignition timing of the spark plug 18 according to the fuel injection pulse width corresponding to the engine load and the engine speed so that the optimum ignition timing is obtained according to the operating conditions. The engine coolant temperature sensor 24 and the accelerator opening sensor 26 are used to retard the basic ignition timing in accordance with the activation state of the three-way catalyst 16 when the engine is warmed up.
Alternatively, control is performed according to detection signals from the throttle opening sensor 27, the rotation speed sensor 23, the air flow sensor 22, and the like.

Until warming-up, such as during a cold start of the engine, the temperature of the three-way catalyst 16 is not activated because the temperature of the three-way catalyst 16 is low, so that the ignition timing is delayed from the basic ignition timing. The three-way catalyst 16 is activated at an early stage, and the retard amount of the ignition timing is corrected based on the accelerator opening or the like so as not to deteriorate the engine operation performance during the warm-up. Control.

At the same time, the control device 21 adjusts the opening degree of the idle control valve 29 provided in the passage 28 bypassing the throttle valve 30 of the intake passage 12 in order to prevent a decrease in engine torque due to the ignition timing retard correction. Correct and increase the amount of intake air.
Reference numeral 31 denotes an idle switch for detecting an idle state.

Here, the ignition timing retard correction for the early activation of the three-way catalyst 16 at the time of warm-up after the engine start or the like will be described with reference to the flowchart of FIG.

First, the starting state of the engine is determined, and when starting the soot motor, normal ignition timing control is performed in order to stabilize the starting, and then, after a complete explosion, the ignition timing is controlled according to the cooling water temperature to promote warm-up. To the retard correction control.

In step 1, it is determined whether or not the starter switch is on. If the starter switch is on, the process proceeds to steps 2-6.

The basic retard amount ADVTID of the ignition timing at the time of idling necessary for promoting the warm-up of the catalyst is calculated from the table shown in FIG. 5 based on the cooling water temperature TW at the time of starting, and similarly, Basic retard amount A when not idle
DVTO is obtained from FIG. 6 by table lookup.

The characteristics of these basic retardation amounts are as follows:
A relatively large amount of retard is set during idling, which has little effect on drivability, in order to promote catalyst warm-up as compared with non-idling.

Further, in order to set a time for maintaining the retard correction control and to obtain a reduction coefficient RTIME for decreasing the correction value with the lapse of time, a table look-up from FIG. By setting up, the set value TMTMP of the delay timer (delay time) is calculated in advance.

Next, in order to ensure a smooth start, a delay amount ADVTMP at the start is set to ADVTMP = 0, that is, the retard amount is set to zero, and a normal start ignition timing data is set (FIG. (Not shown), the ignition timing ADV is calculated by table lookup, and the routine proceeds to step 25, where the ignition timing ADV = ADV-ADVT.
MP.

Therefore, at the time of this start, there is no retard correction of the ignition timing, and a smooth start of the engine is guaranteed.

When the starting operation is completed, steps 10-2
Then, the process proceeds to step S4, where the retard amount of the ignition timing is calculated based on the retard data read at the start.

When it is detected that the starter switch is turned off, the routine proceeds to step 10, where it is determined whether a TMTMP time set based on the cooling water temperature has elapsed since the starter switch was turned off. This TMTMP becomes larger as the cooling water temperature at the start is lower, which means that the ignition timing is corrected for the retard for a longer period after the start.

If the set time has not elapsed, at step 11, the reduction coefficient RTIME is set to 1.0. As described later, a reduction coefficient RTIME of 1.0 means that
The correction rate of the calculated retard amount is 1.0, which means that the retard is directly delayed according to the basic retard amount.

On the other hand, when the set time TMTMP has elapsed, a predetermined TMT
It is determined whether the MPG # time has elapsed. FIG. 8 (A)
As shown in the figure, until the TMTMPG # time elapses, the reduction coefficient RTIME is a region where the reduction coefficient RTIME becomes smaller than 1.0.
ME is calculated.

RTIME = │ (TMKAI-TMTMP) -TMTMPG # │ / TMTM PG # (1) where TMKAI: the elapsed time counter value after the starter switch is turned off The reduction coefficient RTIME is gradually reduced from 1.0 because After the elapse of the time TMTMP, the calculated retard correction amount is decreased to prevent the ignition timing from changing stepwise at the end of the retard correction.

The set time (TMTMP + TMTMP)
G #) has elapsed, the reduction coefficient RT is determined in step 14.
Assuming that IME = 0, the ignition timing retard correction is ended.

With these, the reduction coefficient RTIME is respectively obtained.
After calculating, the process proceeds to step S15.

Step 15 is to judge whether the engine is idling or not based on the on / off state of the idle switch 31, whereby different ignition timing retard correction characteristics are obtained. In other words, Steps 16 and 18 are performed at the time of idling.
Steps 20 to 23 calculate the amount of retard at the time of non-idling.

First, at the time of idling, a basic ignition timing ADV required for idling operation is obtained from a map (not shown).
Next, FIG. 8 shows a correction ratio GISCMX (a value of 1.0 or less) for preventing a decrease in the idle speed due to the retardation of the ignition timing.
It is calculated by the following equation with reference to (B).

GISCMX = (ISCMAX-NRDTY # -RISCON) * GRED T # (2) where NRDTY # is a predetermined constant, GRED
T #: Predetermined coefficient Here, ICSMAX is a control value at which the idle control valve 29 is maximized, and RISCON is a control value at which the idle control valve 29 is opened.
Therefore, when the control duty approaches the maximum value ICSMAX, that is, when the idle control valve 29 is very open to prevent the idling speed from decreasing, the retard amount is reduced. The correction ratio GISCMX approaches zero.

In step 18, based on the basic retard amount ADVTID read at the time of starting, the retard amount ADVTMP is obtained from the correction coefficient GISCMX and RTIME.
Is determined by the following equation.

ADVTMP = ADVTID * GISCMX * RTIME (3) After calculating the retard amount, the process proceeds to step 25, and the basic ignition timing ADV is corrected based on the retard amount ADVTMP.

The basic retard amount ADVTID increases as the cooling water temperature decreases, and accordingly, the retard amount from the optimal ignition timing increases accordingly. By retarding in this way, the exhaust gas temperature rises and the three-way catalyst 16 The temperature rise is also accelerated accordingly.

When the opening of the idle control valve 29 for maintaining the idling speed at a predetermined value is large, that is, when the control for maintaining the idling speed is small, the correction coefficient GISCMX is used to determine the ignition timing. Decreasing (restricting) the amount of retard correction and raising the exhaust temperature, rather than warming up the catalyst,
Prioritize stabilizing idle rotation.

Further, as described above, the reduction coefficient RTIM
E gradually approaches zero as the elapsed time after the start becomes longer, thereby gradually reducing the amount of retardation of the ignition timing and terminating when the retard correction is completed and the normal ignition timing is returned. The difference in the ignition timing before and after is eliminated. This prevents unnecessary retardation and improves fuel economy,
A torque step is prevented from occurring at the end of the retard control, and the drivability is smoothened.

Next, when the vehicle is not idling, that is, when the accelerator pedal is depressed, the routine proceeds to step 20, where the ignition timing ADV during the non-idle operation is read from a map (not shown), and then a correction term for the basic retard amount is calculated. I do.

The correction term includes a retard correction rate ADVTN for the engine speed shown in the map of FIG.
Retard correction rate ADVTTP for engine load in map
And a retard correction rate ADVTTV for the throttle opening (or accelerator opening) shown in FIG. 11, and each is calculated by a table lookup.

The correction rate ADVTN based on the rotation speed takes the maximum value (1.0) in the middle rotation range, gradually decreases in the low rotation range and the high rotation range, and depends on the correction ratio ADVTTP due to the load and the throttle opening. The correction rate ADVTTV has a characteristic that maintains the maximum value (1.0) up to a predetermined value, but gradually decreases at a value higher than the predetermined value.

In step 22, the minimum value of these correction terms is determined as the correction value GJYKEN = ADVTN, ADVTTP
Alternatively, select as ADVTTV.

Then, based on the non-idle basic retard amount ADVTO read at the time of starting in step 23,
The retard amount ADVTMP including this correction coefficient is calculated by the following equation, and the basic ignition timing is corrected in step 25.

ADVTMP = ADVTO * GJYKEN * RTIME (4) Therefore, this retardation correction amount changes according to the engine speed, the load, and the throttle opening, and is selected such that the retardation amount is minimized. Therefore, the operation performance of the engine, including acceleration during warm-up and high-load operation, is maintained satisfactorily.

It is the same as the control at the time of idling that the retard amount decreases with the lapse of time after the start and the occurrence of the torque step at the end of the retard correction is prevented.

In this way, the ignition timing is retarded, the exhaust gas temperature is raised, and the catalyst is activated. However, in order to compensate for the decrease in engine torque caused by the ignition timing retard control, In the present invention, the air amount is simultaneously increased and corrected.

Regarding the increase correction, specifically, control for changing the opening of the idle control valve 29 in accordance with the retard amount of the ignition timing will be described with reference to the flowchart of FIG.

When the ignition timing is delayed, the generated torque of the engine relatively decreases. Therefore, by increasing the intake air by bypassing the intake throttle valve 30 in accordance with the retard amount, the torque reduction is compensated for, the idling speed is prevented from fluctuating in an unstable manner, and the torque generated with respect to the accelerator opening is reduced. Is maintained the same as during normal operation to prevent the driving feeling from deteriorating.

First, in steps 30 to 31, various sensors are checked, idle conditions are checked, an idling basic duty (DUTY) is calculated, and various correction amounts are calculated.

If the idle switch 31 is on, if it is on, then in step 34, the air increase ISCRTD at the time of ignition timing retard correction is determined by the following equation according to the ignition timing retard amount ADVTMP. Is calculated as follows.

ISCRTD = Qshw * ADVTMP * ISRTID # (5) Where, Qshw: basic air amount, ISCRID #: conversion coefficient corresponding to torque decrease due to retardation. On the other hand, when idle switch 31 is off, ,
In step 35, the non-idle-time increased air amount ISCRTD is obtained by the following equation.

ISCRTD = Qshw * ADVTMP * ISRTNI # (6) In this case, ISCRTNI # is a conversion coefficient for compensating for the torque reduction.
9 is calculated as follows.

It should be noted that ISCRTID # and ISCRTNI
The reason for using a different coefficient of # is that the ignition timing is set near MBT during non-idling, but is advanced more than at idle, so that the torque change is large, and therefore the conversion coefficient is set to ISCRTID #. > ISCRTNI #.

Then, in step 36, the control duty ISC of the idle control valve 29 is calculated according to the following equation.

ISC = Basic DUTY + various correction amounts + ISCRTD (7) The opening of the idle control valve 29 is controlled by this ISC, and the opening increases as the ISC increases.
The amount of air introduced by bypassing the throttle valve 30 increases, thereby compensating for the decrease in torque due to the ignition timing retard control, and returning the idle speed to the target value.

In step 37, the ISC maximum value I
From the relationship between SCMAX and the minimum value ISCMIN, restrictions are imposed so that none of them is exceeded.

Therefore, when the ignition timing is corrected to retard the activation of the three-way catalyst 16, the fluctuation (decrease) in the idle speed caused by the decrease in the output torque of the engine is reduced by the opening of the idle control valve 29. It can be compensated by increasing.
In addition, the torque characteristic with respect to the accelerator opening during traveling also generates the same torque as that at the time of non-retarding, so that the driving feeling does not deteriorate, and the ignition timing may be retarded depending on the operating conditions. Although there is a region where it is not possible, even in such a case, the air amount is corrected according to the ignition timing, so that even if the region shifts to this region and the ignition timing is advanced, the torque does not suddenly change, and stable Smooth power characteristics can be exhibited.

FIG. 13 shows another embodiment.

This realizes stable control with less torque fluctuation by adding a correction in consideration of a response delay corresponding to a pressure change in the volume of the intake manifold to the increase in the amount of air.

Steps up to step 35 are the same as those in the flow chart of FIG. 12. However, in step 41, in order to compensate for the delay in the pressure response of the intake system, the advance correction rate ADGIN is set in relation to the engine load (fuel injection pulse width Tp). Specified Figure 14
Is obtained by table lookup from the map.

The idle control valve 29 or the intake throttle valve 30
Therefore, immediately after the ignition timing is switched to the retard side, a response delay occurs in increasing or decreasing the intake air amount by an amount corresponding to a pressure change corresponding to the volume of the intake manifold.

In this case, the response delay increases as the manifold volume increases, and therefore, as shown in FIG.
GIN is set corresponding to the manifold volume. In addition,
The reason why the correction factor is increased as the fuel injection pulse width Tp is increased is that the throttle valve differential pressure is decreased as the Tp is increased, and the intake ratio of the bypass air amount to the same idle control valve opening is reduced.

Then, in step 42, the above-mentioned air increase ISCRTD is corrected based on the compensation coefficient ADGIN as shown in the following equation, and the leading advance of the first-order lag is compensated.

ADISRTn = ISCRTDn-1 + (ISCRTDn-ISCRTDn-1) × ADGIN (8) Here, the compensation coefficient ADRISRTn is obtained by multiplying the difference between the previous and current air increments ISCRTDn-1 and ISCRTDn by the correction rate ADGIN. The result is added to the previous ISCRTDn-1 to obtain a first-order lag of the air amount.

In step 43, the compensation coefficient ADISR
The control duty ISC is calculated according to the following equation based on Tn.

ISC = Basic DUTY + various correction amounts + ADISRTn + OKURI (9) Here, OKURI maintains the opening of the idle control valve 29 within a predetermined opening, and may fall into a substantially uncontrollable state. In order not to use, for example, ADI
If the value of SRTn is larger than a positive or negative predetermined value, the opening degree of the idle control valve 29 becomes the maximum flow rate or a negative side below formally zero. In other words, the portion that is 100% or more and the portion that is 0% or less are stored in a memory called OKURI, and this OKURI is read out at the time of the next ISC calculation, and this value is reflected in the control duty. .

FIG. 15 shows a time chart (waveform diagram) of this air increase control. At the start of the ignition timing retard control, the required ADISRTn becomes very large temporarily, and the control duty ISC is formal. May exceed 100%, but this amount is held as OKURI, and the accumulated amount is sequentially added, so that the ISC is within the control range of the idle control valve 29 and the volume of the intake manifold is reduced. The response delay (first-order delay) of the corresponding intake air is compensated, the air increase accompanying the ignition timing retard is performed with good response, and stable compensation control with very little torque fluctuation (decrease) is realized.

That is, by sequentially adding (or subtracting) the accumulated amount as OKURI, the idle control valve 2
9 is not increased only at the moment of the ignition timing retard switching, but is taken into account in anticipation of the air delay. Therefore, as compared with a case where the air is simply increased as indicated by the characteristic indicated by the dotted line, the torque is reduced. There is little fluctuation and stable power performance can be obtained.

FIG. 15 shows an example in which the ignition timing is retarded and advanced in a stepwise manner for convenience of explanation, but actually changes gradually.

In the above embodiment, the opening of the idle control valve 29 in the passage bypassing the intake throttle valve 30 is controlled in order to increase the amount of air. An electronically controlled throttle valve driven by an actuator which is provided in an intake system and controls the opening of the air control valve to increase or correct the amount of air, or is not mechanically linked to an accelerator pedal as the intake throttle valve 30. The opening degree of the electronic control throttle valve can be controlled in accordance with the increase signal.

[0075]

As described above, according to the present invention, when the ignition timing is controlled to activate the catalyst such as when the engine is started at a low temperature, the ignition timing retard amount is simultaneously reduced when the engine is in the idle state.
And the amount of retard when not idling.
The retard amount and intake air amount or throttle opening of each ignition timing
The intake air amount is increased and corrected in accordance with the signal, and the generated torque of the engine is maintained the same as when the ignition timing is not retarded. Therefore, even though the ignition timing is retarded, the operation performance does not change from the normal operation, and no torque step occurs even if the ignition timing retard amount is switched depending on the operation region.

Further, by compensating for the delay in increasing the air amount, there is no delay in the intake air at the time of increasing the air amount, and it is possible to reliably prevent the torque fluctuation during the retard control of the ignition timing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a basic configuration of a first invention.

FIG. 2 is a configuration diagram showing a basic configuration of a second invention.

FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 4 is a flowchart showing an ignition timing retard control operation.

FIG. 5 is a characteristic diagram showing a basic retard amount during idling based on a relationship between cooling water temperature.

FIG. 6 is a characteristic diagram showing a basic retard amount at the time of non-idling based on a relationship of cooling water temperature.

FIG. 7 is a characteristic diagram showing a delay time of a decrease coefficient based on a relationship of a cooling water temperature.

8A is a characteristic diagram illustrating a characteristic of a decrease coefficient based on a time relationship, and FIG. 8B is a characteristic diagram illustrating a relationship between a correction rate and a control duty value.

FIG. 9 is a characteristic diagram showing a relationship between an engine speed and a retard amount correction rate.

FIG. 10 is a characteristic diagram showing a relationship between an engine load and a retard amount correction rate.

FIG. 11 is a characteristic diagram showing a relationship between a throttle opening and a retard amount correction rate.

FIG. 12 is a flowchart showing a control operation of the idle control valve.

FIG. 13 is a flowchart showing another embodiment of the control operation of the idle control valve.

FIG. 14 is a characteristic diagram showing a relationship between an engine load and a compensation coefficient.

FIG. 15 is a time chart showing the relationship between the control operation of the idle control valve and the generated torque with respect to switching of the ignition timing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Basic ignition timing calculation means 2 Delay angle calculation means 3 Ignition signal output means 4 Increase correction air flow calculation means 5 Air flow control means 6 Delay compensation means 11 Engine body 12 Intake passage 13 Exhaust passage 16 Three-way catalyst 18 Ignition plug 21 Control device 22 Air flow sensor 23 Revolution speed sensor 24 Cooling water temperature sensor 27 Throttle valve (throttle) opening sensor 29 Idle control valve

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F02P 5/15 F02P 5/15 E (56) References JP-A-62-189351 (JP, A) JP-A-61-76741 ( JP, A) JP-A-53-20023 (JP, A) JP-A-5-332178 (JP, A) JP-A-5-44555 (JP, A) JP-A-61-205377 (JP, A) JP 58-119942 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/04 315 F01N 3/20 F02D 41/08 315 F02D 43/00 301

Claims (2)

(57) [Claims] A means for calculating a basic ignition timing from operating conditions; a means for calculating a retardation amount of an ignition timing necessary for activation of the catalyst from the operating conditions; means for outputting an ignition signal modified Te, and means that determines whether an idle state, the ignition timing
The retard amount of the idle state and the non-idle state
The ignition timing is set separately for the ignition timing and the ignition timing is retarded.
Intake air according to angle and intake air amount or throttle valve opening signal
An air amount control device for an internal combustion engine, comprising: means for calculating an increase correction amount of air; and air amount control means for increasing an intake air amount in accordance with the increase correction amount. 2. A means for calculating a basic ignition timing from operating conditions, a means for calculating a retardation amount of an ignition timing necessary for activation of a catalyst from the operating conditions, and the basic ignition timing according to the retardation amount. Means for outputting a corrected ignition signal, means for calculating an increase correction amount of the intake air according to the retard amount of the ignition timing and the intake air amount or the throttle opening signal, and an intake manifold for the increase correction amount. An air amount control device for an internal combustion engine, comprising: a delay compensating unit that corrects according to a volume and an engine load; and an air amount control unit that increases an intake air amount according to the correction amount.