JPH11107825A - Air amount controller for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform control so as to set a proper air amount without a misfire or acceleration when speed reduction fuel cut is prohibited because of a high catalyst temperature. SOLUTION: Fuel cutting is performed during speed reduction running where a throttle valve is fully closed and an engine speed is equal to a specified speed or higher (S1), but when a catalyst temperature is equal to a specified value or higher, speed reduction fuel cutting is prohibited (S2). For prohibiting the speed reduction fuel cutting, an auxiliary air amount supplied to the engine by bypassing the throttle valve is controlled to a target boost according to an engine speed (S4, and S50).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine air amount control device, and more particularly to a technique for appropriately controlling an engine intake air amount in a driven operation state of an engine in which fuel cut is prohibited.

[0002]

2. Description of the Related Art Conventionally, a deceleration fuel cut for stopping fuel supply to an engine in a deceleration operation state, which is a driven operation state of the engine, has been known, but under a condition in which the temperature of a catalyst for purifying exhaust gas is high. When the deceleration fuel cut is performed, the progress of catalyst deterioration is accelerated. Therefore, it is desired that the deceleration fuel cut be prohibited when the catalyst temperature is high, and fuel be supplied and burned normally.

However, at the time of deceleration, the throttle valve is fully closed and the negative pressure is increased. Therefore, in order to burn without causing misfire, air must be supplied through a bypass passage that bypasses the throttle valve. Is done. A technique for controlling the amount of auxiliary air during deceleration is disclosed in
There has been one disclosed in Japanese Patent No. 78847.

In this method, a deceleration state is detected based on a throttle opening, a driving time of an auxiliary air valve is changed in accordance with a closing speed of a throttle valve and an opening change width, and a fuel supply amount is also changed. By deciding based on the above throttle information, an attempt is made to control the air-fuel ratio to an optimum even during deceleration.

[0005]

However, if the amount of air at the time of deceleration is insufficient, a misfire occurs, and if the amount of air is excessive, torque is generated and acceleration occurs. It is necessary to control the air amount to a value that can prevent acceleration while avoiding misfire. However, in the conventional configuration in which the auxiliary air amount is determined only from the information on the throttle valve opening, the required air amount cannot always be supplied depending on the engine speed, and there is a possibility that misfire or acceleration may occur. It turned out experimentally.

Also, due to a change in air pressure or the like, the required amount of air cannot be controlled with high accuracy, and there is a possibility that misfire or acceleration may occur. Further, there is a possibility that the required air amount cannot be obtained immediately after the shift to the deceleration due to a response delay of the auxiliary air amount control valve. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can supply a required amount of air with high accuracy during a deceleration operation in which fuel cut is prohibited (an engine driven operation state), thereby causing misfire or acceleration. It is an object of the present invention to provide an air amount control device capable of obtaining combustion without causing combustion.

It is another object of the present invention to be able to supply the air amount required at the time of deceleration (driven driving state) with good response.

[0008]

Therefore, the invention according to claim 1 has a configuration in which the amount of air supplied to the engine increases as the engine speed increases in a driven operation state of the engine involving combustion. . According to this configuration, in the driven operation state in which the fuel is normally supplied without performing the fuel cut, the amount of air supplied to the engine is increased as the engine rotation speed is higher, and the amount of air supplied to the engine is different for each engine rotation speed. The target air amount is controlled to a target boost that does not cause misfire or acceleration.

In the present application, the driven operation state of the engine is, for example, an engine mounted on a vehicle.
The engine is in a so-called engine braking state, in which the throttle valve is almost fully closed during deceleration operation or when the vehicle is traveling on a downhill, and the engine is driven by receiving rotational force from the drive wheels of the vehicle in reverse. Is higher than a predetermined rotation speed.

According to a second aspect of the present invention, there is provided an operating condition detecting means for detecting an operating condition of an engine, an air amount control valve for controlling an amount of air supplied to the engine, and a rotational speed detecting device for detecting a rotational speed of the engine. Means, and when the driven state of the engine accompanied by combustion is detected by the operating state detecting means, the higher the rotation speed detected by the rotation speed detecting means, the larger the amount of air supplied to the engine. Air amount control means for controlling the air amount control valve.

With this configuration, in the driven operation state of the engine involving combustion, the opening of the air amount control valve is controlled such that the higher the engine speed, the larger the intake air amount of the engine. The air amount control valve may be a throttle valve that is opened and closed by an actuator, or may be an auxiliary air amount control valve that is interposed in a bypass passage provided to bypass the throttle valve. good.

The invention according to claim 3 is configured as shown in FIG. In FIG. 1, the operating state detecting means is means for detecting the operating state of the engine, and the fuel cut means is provided when the predetermined driven operating state of the engine is detected by the operating state detecting means. Stop fuel supply. Further, the catalyst temperature detecting means is means for detecting the temperature of the catalyst interposed in the exhaust passage of the engine, and the fuel cut prohibiting means is provided when the temperature of the catalyst detected by the catalyst temperature detecting means is higher than a predetermined value. At one point, the stopping of fuel supply by the fuel cut means is prohibited.

On the other hand, the auxiliary air amount control valve is interposed in a bypass passage that bypasses the throttle valve, and controls the amount of auxiliary air supplied to the engine from the bypass passage. The rotational speed detecting means is means for detecting the rotational speed of the engine, and the target auxiliary air amount setting means is configured to detect the target auxiliary air amount supplied to the engine when the rotational speed detected by the rotational speed detecting means is high. Set a larger value sometimes.

The auxiliary air amount control means is supplied to the engine when the engine is in the predetermined driven operation state and when the fuel supply prohibition is prohibited by the fuel cut prohibition means. The auxiliary air amount control valve is controlled so that the auxiliary air amount becomes a target auxiliary air amount set by the target air amount setting means. According to this configuration, the fuel cut is basically performed in the driven operation state of the engine. However, when the catalyst temperature is high and the fuel cut results in speeding up the catalyst deterioration, the fuel cut is prohibited and the fuel supply is performed. . Then, in a driven operation state involving combustion in which fuel cut is prohibited based on the catalyst temperature, the auxiliary air amount is increased as the engine speed is higher.

According to a fourth aspect of the present invention, a cut valve that opens when the engine is in the predetermined driven operation state according to the suction negative pressure of the engine is interposed in the bypass passage. With this configuration, even if the auxiliary air amount control valve is open, if the cut valve is closed, the supply of the auxiliary air via the bypass passage is not performed, and
Since the cut valve is opened and closed in accordance with the suction negative pressure, the bypass passage is set to be opened only in a state where the suction negative pressure requiring the supply of auxiliary air is large (a state in which the absolute pressure is reduced to zero when the vacuum is zero). obtain.

According to a fifth aspect of the present invention, when the temperature of the catalyst detected by the catalyst temperature detecting means is equal to or higher than the predetermined value, the degree of opening of the auxiliary air amount control valve is adjusted. Is controlled in advance to a target opening corresponding to the target auxiliary air amount. According to this configuration, when the catalyst temperature is in a high temperature state in which the fuel cut is prohibited, the auxiliary air amount control valve is opened before the driven operation state corresponding to the driven operation state in which fuel is supplied. The required air amount is immediately obtained by controlling the opening of the cut valve when the operation is actually shifted to the driven operation state.

According to the present invention, the difference between the opening degree of the auxiliary air amount control valve and the target opening degree when the operation state of the engine shifts to the predetermined driven operation state is equal to or more than a predetermined value. At one time, a fuel cut forcing means based on an opening difference for forcibly stopping the supply of fuel to the engine in preference to the fuel cut prohibiting means is provided. According to such a configuration, in the configuration in which the opening degree of the auxiliary air amount control valve is controlled in advance, when the operation mode is shifted to the driven operation state before the target opening degree is reached, the required auxiliary air amount is changed to the driven operation state. If it is not possible to obtain from the initial stage, the fuel cut is performed to prevent the occurrence of misfire or the like due to insufficient air volume.

In the invention according to claim 7, the cut valve is kept closed in the open state of the throttle valve prior to the state of the suction negative pressure. According to such a configuration,
When the throttle valve is in the open state, the cut valve is kept closed to avoid torque fluctuation due to the supply of the auxiliary air amount in the normal running state. According to the present invention, there is provided a suction negative pressure detecting means for detecting the suction negative pressure of the engine as an absolute pressure, wherein the target auxiliary air amount setting means sets a target auxiliary air amount in accordance with the detected rotation speed and the suction negative pressure. The configuration is such that the amount of auxiliary air is set.

According to this configuration, the amount of auxiliary air is controlled based on the engine speed, and the amount of auxiliary air that cannot be controlled to the desired suction negative pressure with the auxiliary air amount corresponding to the speed due to a change in air pressure or the like is actually reduced. Is corrected on the basis of the detection result of the suction negative pressure (absolute pressure). According to a ninth aspect of the present invention, there is provided a misfire detection means for detecting misfire of the engine, wherein the target auxiliary air amount setting means sets a target auxiliary air amount according to the detected rotation speed and the presence or absence of misfire. did.

According to this configuration, when a misfire occurs due to a shortage of the auxiliary air amount, it is possible to increase and correct the auxiliary air amount according to the engine speed based on the occurrence of the misfire. According to the tenth aspect of the invention, when the auxiliary air amount controlled by the auxiliary air amount control means exceeds a predetermined range, the auxiliary fuel forcibly stopping the fuel supply to the engine is given priority over the fuel cut prohibition means. A configuration is provided in which a means for forcing fuel cut based on the amount of air is provided.

According to this configuration, when the auxiliary air amount (indicated value) exceeds the normally required range, the target air amount cannot be controlled due to a component failure or the like, and a misfire or acceleration may occur. By performing a fuel cut, it is possible to prevent misfire and acceleration. In the invention according to claim 11, during the control of the auxiliary air amount by the auxiliary air amount control means, when an acceleration operation state is detected by the operation state detection means, priority is given to the fuel cut prohibition means to the engine. An acceleration fuel cut forcing means for forcibly stopping the fuel supply is provided.

According to this configuration, when the vehicle accelerates during the control of the auxiliary air amount, it is determined that the auxiliary air amount larger than the required amount is supplied, and the fuel cut is executed to eliminate the accelerated state. .

[0023]

According to the first or second aspect of the present invention, the amount of air in the driven operation state can be controlled to an appropriate amount for each engine speed, and combustion can be performed without causing misfire or acceleration. effective. According to the third aspect of the invention, it is possible to suppress the catalyst deterioration due to the fuel cut and to control the air amount without causing misfire and acceleration when the fuel cut is prohibited to suppress the catalyst deterioration. .

According to the invention described in claim 4, there is an effect that the supply of the auxiliary air amount in an unnecessary state can be avoided. According to the fifth aspect of the invention, the opening degree of the auxiliary air amount control valve can be controlled in advance to the opening degree required at the time of deceleration, so that the responsiveness of the air amount control can be improved. There is.

According to the sixth aspect of the present invention, it is possible to avoid a shift to a driven operation state involving combustion while the opening of the auxiliary air amount control valve has not reached the target opening. is there. According to the seventh aspect of the invention, there is an effect that it is possible to reliably prevent a torque fluctuation from occurring due to the supply of an unnecessary amount of auxiliary air when the throttle valve is opened.

According to the eighth aspect of the present invention, there is an effect that the target suction negative pressure (air amount) can be accurately controlled even if there is a change in the atmospheric pressure or the like. According to the ninth aspect of the present invention, there is an effect that occurrence of misfire due to insufficient air amount can be reliably prevented. According to the tenth aspect of the present invention, by performing a fuel cut by judging a state in which the required air amount cannot be controlled due to a component failure or the like, there is an effect that combustion accompanied by misfire and acceleration can be avoided.

According to the eleventh aspect of the invention, there is an effect that occurrence of acceleration due to excessive air amount can be reliably prevented.

[0028]

Embodiments of the present invention will be described below. FIG. 2 is a diagram showing a system configuration of the engine according to the first embodiment. In the engine 1, air filtered by an air cleaner 2 is measured by a throttle valve 3, and is supplied to a cylinder 1 via an intake valve 4. Is sucked.

Each cylinder of the engine 1 is provided with an electromagnetic fuel injection valve 5 for directly injecting fuel (gasoline) into the combustion chamber, and the fuel injected from the fuel injection valve 5 is mixed into the cylinder. Qi is formed. The air-fuel mixture in the cylinder is ignited and burned by spark ignition by a spark plug 6, and the combustion exhaust gas is discharged through an exhaust valve 7, purified by a catalyst 8, and released to the atmosphere.

The engine 1 in the present embodiment constitutes a direct injection spark ignition engine with the above configuration, but may be a port injection spark ignition engine in which the fuel injection valve 5 injects fuel into an intake port. A control unit 10 containing a microcomputer controls fuel injection by the fuel injection valve 5 and ignition by a spark plug 6 (energization to an ignition coil (not shown)) by arithmetic processing based on detection signals from various sensors.

The various sensors include an intake air flow rate Q
11, a position sensor 12 that outputs a position signal POS for each 1 ° CA, and a reference signal (reference angle signal) REF for each reference crank angle.
, An air-fuel ratio sensor 15 for detecting the air-fuel ratio of the combustion mixture, a throttle sensor 16 for detecting the opening TVO of the throttle valve 3, and a coolant temperature Tw.
Is provided with a water temperature sensor 17 for detecting the temperature.

The control unit 10 calculates the engine speed Ne based on the position signal POS or the reference signal REF, and functions as a rotation speed detecting means.
Alternatively, it is realized by the reference sensor 13 and the control unit 10. Further, a bypass passage 21 is provided to bypass the throttle valve 3, and an auxiliary air amount control valve 22 (air amount control valve 22) driven to open and close by an actuator such as a step motor so as to control the opening degree is provided in the bypass passage 21. ) Is interposed, and the control unit 10
By controlling the opening of the auxiliary air amount control valve 22, the amount of auxiliary air supplied to the engine via the bypass passage 21 is controlled.

The control unit 10 determines the basic fuel injection amount Tp based on the intake air flow rate Q detected by the air flow meter 11 and the engine rotation speed Ne calculated based on the position signal POS or the reference signal REF. On the other hand, the basic fuel injection amount Tp is corrected based on the coolant temperature Tw, the air-fuel ratio detected by the air-fuel ratio sensor 15, and the like to calculate the final fuel injection amount Ti. Then, by supplying an injection pulse signal having a pulse width corresponding to the fuel injection amount Ti to the fuel injection valve 5 at a predetermined injection timing, fuel supply to the engine 1 is controlled.

When the throttle valve 3 is fully closed and the engine speed Ne is a deceleration operation at a predetermined speed or more (a predetermined driven operation state), the control unit 10 controls the fuel injection by the fuel injection valve 5. Control to stop (hereinafter,
(Referred to as deceleration fuel cut) to reduce HC emissions and improve fuel efficiency (fuel cut means). However, if the fuel cut is performed in a state where the temperature of the catalyst 8 is high, the catalyst 8 will be deteriorated. Therefore, when the temperature of the catalyst 8 is equal to or higher than the predetermined temperature, the deceleration fuel cut is prohibited. (Fuel cut prohibition means).

In a state where the deceleration fuel cut is prohibited, the control unit 10 controls the auxiliary air amount control valve 22 as shown in the flowchart of FIG. Controlling the amount. In the flowchart of FIG. 3, in step 1 (denoted by S1 in the figure; the same applies hereinafter), it is determined whether or not a deceleration fuel cut condition is satisfied.

If the condition is a deceleration fuel cut condition, the process proceeds to step 2, where it is determined based on the temperature of the catalyst 8 whether or not the condition for prohibiting the deceleration fuel cut is satisfied. The temperature of the catalyst 8 may be directly detected by a temperature sensor, or may be estimated from an engine load, an engine rotation speed Ne, or the like (catalyst temperature detecting means).

If the catalyst temperature is so low that the deceleration fuel cut can be executed, the routine proceeds to step 3, where the deceleration fuel cut is executed. On the other hand, when the catalyst temperature is high and the deceleration fuel cut is prohibited, the fuel injection is normally performed. However, when the throttle valve 3 is fully closed, the negative pressure becomes high, the air amount becomes insufficient, and misfire occurs. Therefore, the air amount is controlled by the auxiliary air amount control valve 22.

More specifically, the routine proceeds to step 4, in which a table in which the target auxiliary air amount is stored in advance corresponding to the engine speed Ne is referred to, and the target auxiliary air amount corresponding to the engine speed Ne at that time is referred to. (Target auxiliary air amount setting means). The target auxiliary air amount is set to a larger value as the engine rotation speed Ne is higher, so that an appropriate auxiliary air amount can be controlled in response to a difference in required air amount depending on the engine rotation speed Ne. . That is, as shown in FIG. 4, the target auxiliary air amount according to the engine rotation speed Ne is the boost of the misfire limit,
The target boost (absolute pressure) between the boost corresponding to N / L (no load) and the target boost (absolute pressure) are set in advance. As a result, the higher the engine speed Ne is, the larger the value is set. Thus, it is possible to control the air amount so that the engine does not accelerate while avoiding the occurrence of misfire.

Steps 1 and 2 correspond to operating state detecting means for detecting a deceleration operation (driven operation) accompanied by combustion. In step 5, the auxiliary air amount control valve is set to the opening degree at which the target auxiliary air amount set in step 4 is obtained.
The opening degree of 22 is controlled (air amount control means, auxiliary air amount control means).

In step 6, the fuel cut is prohibited in response to the result of the determination in step 2 (fuel cut prohibiting means), and combustion is performed in a state where the auxiliary air amount can be obtained through the auxiliary air amount control valve 22. Let FIG. 5 is a diagram showing a system configuration of an engine according to the second embodiment. In FIG. 5, a boost sensor 18 for detecting a boost (suction negative pressure) of the engine 1 as an absolute pressure with a vacuum of 0 is used. The only difference is that a suction negative pressure detecting means is provided. Hereinafter, the boost is indicated by an absolute pressure.

In the second embodiment, as shown in the flowchart of FIG. 6, the auxiliary air amount control valve 22 is controlled in the deceleration operation state in which the fuel cut is prohibited. In the flowchart of FIG. 6, in step 11,
It is determined whether or not the condition for the deceleration fuel cut is satisfied. If the condition is satisfied, it is determined in step 12 whether or not the deceleration fuel cut is to be prohibited based on the temperature of the catalyst 8.

When the temperature of the catalyst 8 is low, the routine proceeds to step 13, where a deceleration fuel cut is executed. On the other hand, if the temperature of the catalyst 8 is high and it is a condition to prohibit the deceleration fuel cut, the routine proceeds to step 14 and proceeds to step 4.
Similarly, the target auxiliary air amount is set based on the engine speed Ne (target auxiliary air amount setting means).

In step 15, the boost PB (absolute pressure with vacuum set to 0) detected by the boost sensor 18 is read. In step 16, a deviation ΔPB between the target boost PBTG in setting the target auxiliary air amount based on the engine rotation speed Ne and the detected actual boost PB is calculated (ΔPB = PBTG−PB).

In step 17, a corrected air amount HOS corresponding to the deviation ΔPB calculated in step 16 is obtained by referring to a table in which the corrected air amount HOS is previously stored according to the deviation ΔPB. The table of the corrected air amount HOS in the above step 17 shows that the larger the absolute value of the deviation ΔPB is, the larger the absolute value of the correction amount HOS is. Also, if the deviation ΔPB is positive, the actual boost PB is the target boost PBTG. When the pressure is lower (when the actual boost is closer to vacuum), a positive value is set as the correction amount HOS, the target auxiliary air amount is corrected to increase, and conversely, the deviation ΔPB is negative. When the actual boost PB is higher than the target boost PBTG (when the target boost is closer to vacuum), a negative value is set as the correction amount HOS, and the target auxiliary air amount is corrected to decrease. It has become. That is, by correcting the target auxiliary air amount with the correction amount HOS, the auxiliary air amount for obtaining the target boost PBTG can be accurately set even if there is a change in the atmospheric pressure or the like.

When the correction amount HOS is set in step 17,
In step 18, the correction amount HOS is added to the target auxiliary air amount set in step 14 to correct it.
Then, the opening of the auxiliary air amount control valve 22 is controlled based on the corrected target auxiliary air amount. And step
At 20, the deceleration fuel cut is prohibited, and combustion is performed in a state where the amount of auxiliary air is obtained as a result of the opening control at step 19 described above.

FIG. 7 is a flowchart showing how the auxiliary air amount is controlled in the third embodiment.
The contents of the control in the third embodiment will be described below as being applied to the system configuration in the first embodiment shown in FIG. In the flowchart of FIG. 7, in step 31, a deceleration fuel cut condition is determined. When the condition is satisfied, the process proceeds to step 32, and it is determined whether or not the fuel cut is prohibited based on the catalyst temperature.

When the catalyst temperature is low and the deceleration fuel cut can be executed, the routine proceeds to step 33, where the deceleration fuel cut is executed. On the other hand, when the catalyst temperature is high and the conditions for prohibiting the deceleration fuel cut are satisfied, the process proceeds to step 34,
As in steps 4 and 14, the target auxiliary air amount is set according to the engine speed Ne.

In step 35, it is determined whether or not a misfire has occurred in the engine 1. Misfire can be detected based on the fluctuation of the engine rotation speed Ne, and if a cylinder pressure sensor is provided, it can be detected based on the cylinder pressure detected by the sensor (misfire detection means). If it is determined in step 35 that a misfire has occurred, the process proceeds to step 36, in which the corrected air amount HOS is increased by a predetermined value Δα1, and if it is determined that no misfire has occurred, the process proceeds to step 37, The correction air amount HOS is reduced by a predetermined value Δα2 (<Δα1). That is, when misfire has occurred, it is determined that the amount of air is insufficient, and the amount of auxiliary air is increased. On the other hand, when misfire is not occurring, the amount of auxiliary air is reduced to avoid acceleration due to excessive supply of air. It is.

In step 38, the target auxiliary air amount set in step 34 is corrected by the correction amount HOS. In step 39, the upper and lower limits of the auxiliary air amount are set based on the engine speed Ne. The upper and lower limits are:
The setting is made in accordance with the no-load and misfire limit boosts shown in FIG.

In step 40, it is determined whether or not the target auxiliary air amount obtained by the correction setting by the correction amount HOS in step 38 is within the range between the upper and lower limits set in step 39. If it is determined in step 40 that the target auxiliary air amount is within the range between the upper and lower limits,
Proceeding to step 41, the auxiliary air amount control valve 22 is controlled in accordance with the target auxiliary air amount, and in step 42, processing for inhibiting deceleration fuel cut is performed.

On the other hand, if it is determined in step 40 that the target auxiliary air amount exceeds the range sandwiched by the upper and lower limits, the process proceeds to step 43, in which a deceleration fuel cut is executed (fuel cut forcing by auxiliary air amount). ). When the target auxiliary air amount exceeds the upper and lower limit values, the target auxiliary air amount is not actually obtained due to the failure of the auxiliary air amount control valve 22, and combustion occurs in a state where misfiring occurs or in an accelerated state. May have been done.

When a misfire occurs, unburned HC may be burned by the catalyst 8 to cause the catalyst 8 to be melted.
When acceleration occurs, operability is greatly impaired, and these are matters to be dealt with prior to the progress of catalyst deterioration due to execution of deceleration fuel cut. Therefore, a deceleration fuel cut is executed to avoid deceleration operation in a state where at least misfire and acceleration occur.

If it is determined in step 40 that the target auxiliary air amount exceeds the range between the upper and lower limits,
Thereafter, it is preferable that the deceleration fuel cut is not prohibited until the ignition switch is turned off, even when the catalyst temperature is high. The flowchart of FIG. 8 shows how the auxiliary air amount is controlled in the fourth embodiment. The control content of the fourth embodiment will be described below as being applied to the system configuration of the first embodiment shown in FIG.

In the flowchart of FIG.
At 51, a deceleration fuel cut condition is determined. When the condition is satisfied, the routine proceeds to step 52, where it is determined whether or not the fuel cut should be prohibited based on the catalyst temperature. When the catalyst temperature is low and the deceleration fuel cut can be executed, the routine proceeds to step 53, where the deceleration fuel cut is executed.

On the other hand, if the catalyst temperature is high and the conditions for prohibiting deceleration fuel cut are to be prohibited, the routine proceeds to step 54, where the target auxiliary air amount is set according to the engine speed Ne, as in steps 4, 14, and 34. I do. In step 55, it is determined whether or not the vehicle speed change ΔVSP (ΔVSP = latest vehicle speed−previous vehicle speed) is equal to or greater than a predetermined value and the vehicle speed VSP indicates an increasing change.

When the vehicle speed VSP is increasing and changing, in other words, when the vehicle is accelerating, it is possible to surely avoid acceleration when a deceleration request is made, even though the deceleration fuel cut is prohibited. In step 53, the deceleration fuel cut is executed. On the other hand, if it is determined that the vehicle speed VSP has not increased, the process proceeds to step 56, where the change ΔNe (ΔNe = newest speed−previous speed) of the engine speed Ne is equal to or greater than a predetermined value, and the engine speed Ne increases. It is determined whether or not it indicates a change.

Then, even when the engine speed Ne is increasing, the program proceeds to step 53, where the deceleration fuel cut is executed. The process of proceeding from step 55 or step 56 to step 53 corresponds to acceleration-time fuel cut forcing means. If the vehicle speed VSP and the engine speed Ne have not both increased and changed, the routine proceeds to step 57, where it is determined whether or not the basic fuel injection amount Tp is equal to or greater than the minimum value. The minimum value corresponds to the minimum injection time at which an injection amount proportional to the injection time is obtained. When the basic fuel injection amount Tp is less than the minimum value, the controllability of the air-fuel ratio may be reduced and a misfire or the like may occur. Therefore, the routine proceeds to step 53, where the deceleration fuel cut is executed.

When both the vehicle speed VSP and the engine speed Ne do not increase and change and the basic fuel injection amount Tp is equal to or greater than the minimum value, the routine proceeds to step 58, where the auxiliary air amount control valve is controlled in accordance with the target auxiliary air amount. 22 is controlled, and in step 59, deceleration fuel cut is prohibited. In the fourth embodiment, the target auxiliary air amount is determined based only on the engine rotation speed Ne. However, as in the second embodiment, the engine rotation speed Ne and the boost sensor 18 are determined.
A configuration for determining a target auxiliary air amount based on the detection result of
Alternatively, in a configuration in which the target auxiliary air amount is determined from the engine rotation speed Ne and the result of misfire detection as in the third embodiment, the vehicle speed VSP, the change in the engine rotation speed Ne, and the basic fuel injection amount are similarly set. The deceleration fuel cut may be executed based on Tp.

FIG. 9 is a system diagram of an engine showing a fifth embodiment, in which the auxiliary air amount control shown in the first to fourth embodiments is applied to the system configuration shown in FIG. It is possible. In FIG. 9, a cut valve 23 which is opened / closed on and off is interposed in a bypass passage 21 downstream of the auxiliary air amount control valve 22.
As shown in FIG. 10, the signal of the boost sensor 18 is processed by a logic circuit provided in the control unit 10 to open and close (energized / deenergized) based on the output of the logic circuit.
Controlled. That is, it is controlled to either the open state or the closed state based on the boost detected by the boost sensor 18, and is controlled not by software processing but by a logic circuit to enhance control reliability. It is.

The cut valve 23 is controlled to open when the boost (absolute pressure) is equal to or lower than the boost (absolute pressure) corresponding to the no-load N / L shown in FIG. 4 and is equal to or lower than the reference boost set at or above the target boost during deceleration. In the state exceeding the reference boost, the control is controlled to be closed, so that it is opened immediately after the shift to the deceleration operation and the supply of the auxiliary air amount via the bypass passage 21 becomes possible.

According to this configuration, the auxiliary air amount control valve 22
Even if there is an open failure, it is possible to prevent the auxiliary air amount from being supplied except during deceleration. The flowchart of FIG. 11 shows the sixth embodiment, and shows the auxiliary air amount control applied to the system configuration of FIG. This figure
In the flowchart of FIG. 11, in step 61, the catalyst 8
It is determined whether or not the temperature is a predetermined high temperature state in which the deceleration fuel cut should be prohibited. When the catalyst temperature is high, the process proceeds to step 62, and the target auxiliary air amount is set to the same value as in the first embodiment in order to cope with the deceleration operation in which the fuel cut is prohibited without waiting for the deceleration operation. Set according to the rotation speed, and in step 63, the auxiliary air amount control valve
The opening degree of 22 is opened corresponding to the target auxiliary air amount.

At step 64, a deceleration fuel cut condition is determined. If the condition is satisfied, the routine proceeds to step 65, where it is determined whether fuel cut is prohibited based on the catalyst temperature. When the catalyst temperature is low and the deceleration fuel cut can be executed, the routine proceeds to step 66, where the deceleration fuel cut is executed.

On the other hand, if the catalyst temperature is high and the conditions are such that the deceleration fuel cut should be prohibited, the routine proceeds to step 67, where the deceleration fuel cut is prohibited. At this time, since the cut valve 23 is controlled to open with a decrease in the boost due to the shift to the deceleration operation, the auxiliary air amount adjusted by the auxiliary air amount control valve 22 that has been opened in advance is immediately supplied to the engine. .

If the opening degree of the auxiliary air amount control valve 22 is controlled after shifting to the deceleration operation, the target auxiliary air amount cannot be obtained immediately due to a response delay of the opening degree change. When it is predicted that the fuel cut will be performed, the opening of the auxiliary air amount control valve 22 is opened to an opening corresponding to the target auxiliary air amount in advance, and the auxiliary valve is cut by the cut valve 23 before the actual deceleration operation. If the cutoff valve 23 is opened with the transition to the deceleration operation while the supply of air is cut off, the response of the cut valve 23 that is opened and closed on and off is good. It is possible to supply an auxiliary air quantity.

After the actual shift to the deceleration operation, the target auxiliary air amount is corrected based on the detection result of the boost sensor 18 and the misfire detection result. It is also possible to adopt a configuration in which a fuel cut shift is made when exceeding a predetermined range, or a fuel cut is made when acceleration is detected. This is described in the seventh and eighth embodiments described later. The same is true for

The flowchart of FIG. 12 shows the seventh embodiment, and shows the auxiliary air amount control applied to the system configuration of FIG. In the flowchart of FIG. 12, in step 71, it is determined whether or not the temperature of the catalyst 8 is in a predetermined high temperature state in which the deceleration fuel cut should be prohibited. If the catalyst temperature is high, the process proceeds to step 72, Without waiting for the operation, the target auxiliary air amount is set in order to cope with the deceleration operation in which the fuel cut is prohibited.In step 73, the opening of the auxiliary air amount control valve 22 is opened to the target auxiliary air amount. deep.

In step 74, it is determined whether or not the throttle valve 3 is fully closed. When the throttle valve 3 is open, the routine proceeds to step 75, in which the cut valve 23 is controlled to be closed in preference to the opening / closing control of the cut valve 23 in accordance with the boost detected by the boost sensor 18. I do. This prevents the auxiliary air amount from being supplied to the engine 1 via the auxiliary air amount control valve 22 when the throttle valve 3 is running with the throttle valve 3 opened. That is, in the present embodiment, as described above, before the deceleration operation, the auxiliary air amount control valve 22
Is opened to an opening degree that meets the demand for deceleration. However, in a running state in which the throttle 3 is open, torque fluctuation occurs when supplementary air is supplied, giving the driver an uncomfortable feeling. Therefore, in order to avoid this reliably, the cut valve 23 is closed when the throttle valve 3 is open regardless of the boost at that time.

On the other hand, when the throttle valve 3 is fully closed, the routine proceeds to step 76, where the deceleration fuel cut conditions other than the throttle valve 3 fully closed are determined. When the condition is satisfied, the routine proceeds to step 77, where the fuel cut is performed based on the catalyst temperature. It is determined whether or not the state should be prohibited. When the catalyst temperature is low and the deceleration fuel cut can be executed, the routine proceeds to step 78, where the deceleration fuel cut is executed.

On the other hand, when the catalyst temperature is high and the conditions for prohibiting the deceleration fuel cut are to be prohibited, the routine proceeds to step 79, where the deceleration fuel cut is prohibited. At this time, the cut valve 18 is controlled to open with a decrease in the boost due to the shift to the deceleration operation. The flowchart of FIG. 13 shows the eighth embodiment, and shows the auxiliary air amount control applied to the system configuration of FIG.

In the flowchart of FIG. 13, in step 81, it is determined whether or not the temperature of the catalyst 8 is at a predetermined high temperature at which the deceleration fuel cut should be prohibited. If the catalyst temperature is high, the process proceeds to step 82. Then, without waiting for the deceleration operation, the target auxiliary air amount is set to cope with the deceleration operation in which the fuel cut is prohibited, and in step 84, the opening degree of the auxiliary air amount control valve 22 is set to the target auxiliary air amount. Keep open.

In step 84, it is determined whether or not the throttle valve 3 is fully closed. When the throttle valve 3 is open, the routine proceeds to step 85, in which the cut valve 23 is controlled to be closed in preference to the opening / closing control of the cut valve 23 in accordance with the boost detected by the boost sensor 18. I do. on the other hand,
When the throttle valve 3 is fully closed, the routine proceeds to step 86, where deceleration fuel cut conditions other than the throttle valve 3 are fully closed are determined. When the condition is satisfied, the routine proceeds to step 87, where the fuel cut should be prohibited based on the catalyst temperature. Is determined.

When the catalyst temperature is low and the deceleration fuel cut can be executed, the routine proceeds to step 88, where the deceleration fuel cut is executed. On the other hand, when the catalyst temperature is high and the conditions are such that the deceleration fuel cut should be prohibited, the routine proceeds to step 89,
Deviation between the opening of the auxiliary air flow control valve 22 and the target opening (deviation =
It is determined whether or not (actual opening-target opening) is within a predetermined range.

Specifically, it is determined whether or not the deviation is smaller than -D1 and the actual opening is smaller than the target opening by a predetermined value D1 or more. D1 is a value corresponding to the difference between the target boost corresponding to the target opening and the boost at the misfire limit. When the actual opening is smaller than the target opening and the difference is equal to or greater than the predetermined value D1, the air amount It is determined that there is a possibility of misfire due to shortage.

Further, it is determined whether or not the deviation is larger than D2 and the actual opening is larger than the target opening by a predetermined value D2 or more. D1 is a value corresponding to a deviation between the target boost corresponding to the target opening and the boost of the no-load N / L. When the actual opening is larger than the target opening and the deviation is equal to or more than the predetermined value D2, It is determined that there is a possibility of acceleration due to excess air.

When the actual opening is smaller than the target opening by a predetermined value D1 or more, or when the actual opening is smaller than the target opening by a predetermined value D2.
If it is larger than this, even if the deceleration fuel cut is prohibited,
Since there is a possibility that misfire or acceleration may occur due to an excess or deficiency of the air amount, the routine proceeds to step 88, where the deceleration fuel cut is executed even though the catalyst temperature is high (fuel cut forcing means based on the difference in the opening degree).

On the other hand, if the target opening degree-predetermined value D1 ≦ actual opening degree ≦ target opening degree + predetermined value D2, there is no excess or deficiency of the air amount that would cause misfire or acceleration. Prohibit deceleration fuel cut. According to this configuration, the catalyst temperature is determined to be high immediately before the deceleration fuel cut condition is satisfied, and the opening of the auxiliary air amount control valve 22 is controlled in advance to an opening that matches the target auxiliary air amount. If the target opening cannot be controlled to the target opening before the operation is started, and if the deviation between the target opening and the actual opening at that time is a relatively large value that causes misfire and acceleration,
Even if the deceleration fuel cut is prohibited, there is a possibility of misfire and acceleration in the initial state. Therefore, the deceleration fuel cut is executed as it is to prevent the occurrence of misfire and acceleration.

The present invention can be applied to an engine having a throttle valve whose opening is electrically controlled and having no passage for bypassing the throttle valve. That is, even in such an engine, in a situation where the output of the engine is not required (for example, a state where the accelerator pedal is depressed by the driver is 0), the throttle valve opening is controlled to be almost fully closed, and the engine rotation speed at this time is reduced. If the rotation speed is equal to or higher than the predetermined rotation speed, the fuel cut is performed. At this time, if both the fuel cut condition and the fuel cut prohibition condition based on the catalyst temperature are satisfied, the minute opening set according to the engine rotation speed is set. Only the throttle valve opening may be increased and corrected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the invention according to claim 3;

FIG. 2 is a system configuration diagram of an engine according to the first embodiment.

FIG. 3 is a flowchart showing the contents of auxiliary air amount control in the first embodiment.

FIG. 4 is a diagram showing a correlation between a boost corresponding to no-load and a misfire limit boost and a target boost.

FIG. 5 is a system configuration diagram of an engine according to a second embodiment.

FIG. 6 is a flowchart showing the contents of auxiliary air amount control according to the second embodiment.

FIG. 7 is a flowchart showing the contents of auxiliary air amount control in a third embodiment.

FIG. 8 is a flowchart showing the contents of auxiliary air amount control in a fourth embodiment.

FIG. 9 is a system configuration diagram of an engine according to a fifth embodiment.

FIG. 10 is a diagram illustrating a drive circuit of a cut valve according to a fifth embodiment.

FIG. 11 is a flowchart showing the contents of auxiliary air amount control in a sixth embodiment.

FIG. 12 is a flowchart showing the contents of auxiliary air amount control in a seventh embodiment.

FIG. 13 is a flowchart showing the contents of auxiliary air amount control in the eighth embodiment.

[Explanation of symbols]

 Reference Signs List 1 engine 3 throttle valve 5 fuel injection valve 8 catalyst 10 control unit 11 air flow meter 12 position sensor 13 reference sensor 15 air-fuel ratio sensor 16 throttle sensor 17 water temperature sensor 18 boost sensor 21 bypass passage 22 auxiliary air amount control valve 23 cut valve

Claims (11)

[Claims] 1. An air amount control device for an engine, wherein the amount of air supplied to the engine is increased as the engine rotational speed increases in a driven operation state of the engine accompanied by combustion. 2. An operating state detecting means for detecting an operating state of the engine; an air amount control valve for controlling an amount of air supplied to the engine; a rotational speed detecting means for detecting a rotational speed of the engine; When the detecting means detects the driven operating state of the engine accompanied by combustion, the air amount is set such that the higher the rotational speed detected by the rotational speed detecting means, the larger the amount of air supplied to the engine. An air amount control device for an engine, comprising: air amount control means for controlling a control valve. 3. An operating state detecting means for detecting an operating state of the engine, and a fuel cut for stopping a fuel supply to the engine when the operating state detecting means detects a predetermined driven operating state of the engine. Means, a catalyst temperature detecting means for detecting a temperature of a catalyst interposed in an exhaust passage of the engine, and when the temperature of the catalyst detected by the catalyst temperature detecting means is a predetermined value or more, the fuel cut means Fuel cut prohibition means for prohibiting fuel supply stop, and a bypass passage bypassing the throttle valve,
An auxiliary air amount control valve for controlling an amount of auxiliary air supplied to the engine from the bypass passage; a rotational speed detecting means for detecting a rotational speed of the engine; Means for setting the target auxiliary air amount to be larger as the rotational speed detected by the means is higher, and stopping the fuel supply by the fuel cut prohibiting means while the engine is in the predetermined driven operation state. The auxiliary air amount control means for controlling the auxiliary air amount control valve so that the auxiliary air amount supplied to the engine is equal to the target auxiliary air amount set by the target air amount setting means. An air amount control device for an engine, comprising: 4. The engine according to claim 3, wherein a cut valve that opens when the engine is in the predetermined driven operation state according to the suction negative pressure of the engine is interposed in the bypass passage. Air flow control device. 5. The auxiliary air amount control means, when the temperature of the catalyst detected by the catalyst temperature detection means is equal to or higher than the predetermined value, sets the opening degree of the auxiliary air amount control valve to the target auxiliary air amount. The air amount control device for an engine according to claim 4, wherein the target opening degree is controlled in advance. 6. When the difference between the opening of the auxiliary air amount control valve and the target opening when the operating state of the engine shifts to the predetermined driven operating state is equal to or greater than a predetermined value, the fuel 6. The air amount control device for an engine according to claim 5, further comprising a fuel cut forcing means based on an opening difference for forcibly stopping the supply of fuel to the engine prior to the cut prohibiting means. 7. The air for an engine according to claim 4, wherein the cut valve is kept closed when the throttle valve is open, prior to the suction negative pressure state. Quantity control device. 8. An intake negative pressure detection means for detecting an intake negative pressure of the engine as an absolute pressure, wherein said target auxiliary air amount setting means includes a target auxiliary air amount according to the detected rotation speed and the suction negative pressure. The air amount control device for an engine according to any one of claims 3 to 7, wherein 9. A target misfire detection means for detecting misfire of the engine, wherein the target supplementary air amount setting means sets a target supplementary air amount according to the detected rotational speed and the presence or absence of misfire. An engine air amount control device according to any one of claims 3 to 8. 10. An auxiliary air amount for forcibly stopping the supply of fuel to the engine prior to the fuel cut prohibition means when the auxiliary air amount controlled by the auxiliary air amount control means exceeds a predetermined range. The air amount control device for an engine according to any one of claims 3 to 9, further comprising a fuel cut forcing means. 11. When the acceleration state is detected by the operation state detection means during the control of the auxiliary air amount by the auxiliary air amount control means, the supply of fuel to the engine is given priority over the fuel cut inhibition means. 4. An acceleration fuel cut forcing means for forcibly stopping the vehicle is provided.
An air amount control device for an engine according to any one of the eleventh to eleventh aspects.