JP3760591B2 - Engine air volume control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air amount control device for an engine, and more particularly to a technique for appropriately controlling an intake air amount of an engine in an engine driven operation state in which fuel cut is prohibited.
[0002]
[Prior art]
Conventionally, a deceleration fuel cut that stops fuel supply to the engine in a deceleration operation state, which is a driven operation state of the engine, is known. However, the deceleration fuel cut is performed under a condition where the temperature of the catalyst that performs exhaust purification is high. When it is executed, the progress of the catalyst deterioration is accelerated. Therefore, it is desirable to inhibit the deceleration fuel cut when the catalyst temperature is high and to normally supply the fuel and burn it.
[0003]
However, when the vehicle is decelerated, the throttle valve is fully closed and the negative pressure becomes high. Therefore, in order to burn without causing misfire, supply of air through the bypass passage that bypasses the throttle valve is required. Conventionally, as a technique for controlling the amount of auxiliary air during deceleration, there has been one disclosed in Japanese Patent Laid-Open No. 58-178847.
[0004]
This detects the deceleration state based on the throttle opening, changes the driving time of the auxiliary air valve according to the closing speed of the throttle valve and the opening change width, and the fuel supply amount is also the above throttle By determining based on the information, an attempt is made to control the air-fuel ratio to an optimum even during deceleration.
[0005]
[Problems to be solved by the invention]
By the way, if the air amount during deceleration is insufficient, misfire occurs, and if the air amount is excessive, there is a problem that torque is generated and acceleration occurs. The air amount during deceleration accelerates while avoiding misfire. It is necessary to control to a value that can prevent this. However, in the configuration in which the auxiliary air amount is determined only from the information on the throttle valve opening as in the conventional case, the required air amount cannot always be supplied depending on the engine speed, and misfire or acceleration may occur. It was found experimentally.
[0006]
In addition, the required air amount cannot be accurately controlled due to a change in atmospheric pressure or the like, and misfire or acceleration may occur. Furthermore, there is a possibility that the required air amount cannot be obtained immediately after shifting to deceleration due to a delay in response of the auxiliary air amount control valve. The present invention has been made in view of the above problems, and can accurately supply the required air amount during deceleration operation (engine driven operation state) where fuel cut is prohibited, thereby causing misfire and acceleration. It is an object of the present invention to provide an air amount control device capable of obtaining combustion without causing it.
[0007]
It is another object of the present invention to be able to supply the amount of air required for deceleration (driven operation state) with good response.
[0008]
[Means for Solving the Problems]
Therefore, the invention of claim 1 isAn operating state detecting unit for detecting an operating state of the engine, a fuel cut unit for stopping fuel supply to the engine when a predetermined driven operating state of the engine is detected by the operating state detecting unit, A catalyst temperature detecting means for detecting the temperature of the catalyst interposed in the exhaust passage; and when the temperature of the catalyst detected by the catalyst temperature detecting means is equal to or higher than a predetermined value, the fuel cut means stops the fuel supply. Fuel cut prohibiting means for prohibiting, an auxiliary air amount control valve for controlling the amount of auxiliary air supplied to the engine from the bypass passage, and a rotation for detecting the rotational speed of the engine. The target auxiliary air amount that is set larger as the rotational speed detected by the rotational speed detecting means is higher. The auxiliary air amount supplied to the engine is the target air amount when the air amount setting unit and the engine are in the predetermined driven operation state and the fuel cut prohibiting unit prohibits the fuel supply from being stopped. Auxiliary air amount control means for controlling the auxiliary air amount control valve so as to be the target auxiliary air amount set by the setting means, and the engine is in the predetermined driven operation state according to the intake negative pressure of the engine In this case, a cut valve that opens at this time is interposed in the bypass passage.
[0009]
According to such a configuration, the fuel cut is basically performed in the driven state of the engine, but when the catalyst temperature is high and the result of the catalyst deterioration is accelerated by the fuel cut, the fuel cut is prohibited and the fuel is supplied. . In a driven operation state with combustion that prohibits fuel cut based on the catalyst temperature, the auxiliary air amount is reduced as the engine speed increases.Do more. In addition,Even if the auxiliary air amount control valve is open, if the cut valve is closed, auxiliary air is not supplied through the bypass passage, and the cut valve is opened and closed according to the suction negative pressure. Therefore, the bypass passage can be set to open only in a state where the suction negative pressure requiring supply of auxiliary air is large (a state where the absolute pressure is zero when the vacuum is zero).
[0010]
Claim2In the described invention, the auxiliary air amount control means sets the opening degree of the auxiliary air amount control valve to the target auxiliary air amount when the catalyst temperature detected by the catalyst temperature detecting means is equal to or higher than the predetermined value. It was set as the structure previously controlled to the target opening degree corresponding to. According to this configuration, when the catalyst temperature is in a high temperature state where prohibition of fuel cut is performed, the auxiliary air amount control valve is opened corresponding to the driven operation state in which fuel is supplied in advance before entering the driven operation state. The degree of air is controlled so that the required air amount can be obtained immediately by controlling the opening of the cut valve when the operation state is actually shifted.
[0011]
Claim3In the described invention, when the difference between the opening degree of the auxiliary air amount control valve and the target opening degree when the engine operating state shifts to the predetermined driven operating state is a predetermined value or more, the fuel A fuel cut forcing means based on an opening difference for forcibly stopping the fuel supply to the engine in preference to the 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, the required auxiliary air amount is changed to the driven operation state before the target opening degree is reached. When it cannot be obtained from the initial stage, the fuel is cut to avoid the occurrence of misfire due to the shortage of air.
[0012]
Claim4In the described invention, the cut valve is held closed when the throttle valve is open in preference to the suction negative pressure state. According to this configuration, when the throttle valve is in the open state, the cut valve is held closed, and torque fluctuation due to the supply of the auxiliary air amount in the normal running state is avoided.
[0013]
Claim5In the described invention, a suction negative pressure detection means for detecting the suction negative pressure of the engine as an absolute pressure is provided, and the target auxiliary air amount setting means is configured to detect a target auxiliary air amount according to the detected rotational speed and the suction negative pressure. It was set as the structure which sets. According to this configuration, the amount of auxiliary air is controlled based on the engine speed, and the amount of air that cannot be controlled to the desired suction negative pressure with the amount of auxiliary air corresponding to the rotational speed due to changes in atmospheric pressure or the like is reduced to the actual suction negative pressure. Correction is performed based on the detection result of the pressure (absolute pressure).
[0014]
Claim6In the described invention, misfire detection means for detecting misfire of the engine is provided, and the target auxiliary air amount setting means sets the target auxiliary air amount in accordance with the detected rotational speed and the presence or absence of misfire. 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 misfire occurrence.
[0015]
Claim7In the described invention, when the auxiliary air amount controlled by the auxiliary air amount control means exceeds a predetermined range, the fuel supply to the engine is forcibly stopped in preference to the fuel cut prohibiting means. The fuel cut forcing means is provided. According to such a configuration, when the auxiliary air amount (indicated value) exceeds the normally required range, it is estimated that the target air amount cannot be controlled due to a component failure or the like, and misfire or acceleration may occur. In addition, by performing fuel cut, misfire and acceleration are prevented.
[0016]
Claim8In the described invention, when an acceleration operation 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 fuel is supplied to the engine in preference to the fuel cut prohibition means. An acceleration fuel cut forcing means for forcibly stopping is provided. According to this configuration, when accelerating during the control of the auxiliary air amount, it is determined that an auxiliary air amount larger than the required amount is supplied, and the acceleration state is eliminated by executing the fuel cut.
[0017]
【The invention's effect】
According to the invention of claim 1,In addition to suppressing catalyst deterioration due to fuel cuts, it is possible to control the amount of air without causing misfires or acceleration when fuel cuts are prohibited in order to suppress catalyst deterioration, and assistance in unnecessary conditions There is an effect that supply of the air amount can be avoided.
[0018]
Claim2According to the described 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, and there is an effect that the responsiveness of the air amount control can be improved.
[0019]
Claim3According to the described invention, there is an effect that it is possible to avoid shifting to a driven operation state involving combustion while the opening degree of the auxiliary air amount control valve does not reach the target opening degree.
[0020]
Claim4According to the described invention, there is an effect that it is possible to surely prevent a torque fluctuation from being caused by supplying an unnecessary auxiliary air amount when the throttle valve is opened.
[0021]
Claim5According to the described invention, there is an effect that the target suction negative pressure (air amount) can be accurately controlled even if there is a change in atmospheric pressure or the like.
[0022]
Claim6According to the described invention, there is an effect that it is possible to reliably prevent the occurrence of misfire due to an insufficient amount of air.
[0023]
Claim7According to the described invention, it is possible to avoid combustion accompanied by misfire and acceleration by determining the state in which the required air amount cannot be controlled due to a component failure or the like and executing the fuel cut.
[0024]
Claim8According to the described invention, there is an effect that it is possible to reliably prevent the occurrence of acceleration due to an excessive amount of air.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.FIG. 1 shows an embodiment.FIG. 2 is a diagram showing a system configuration of the engine. In the engine 1, air filtered by an air cleaner 2 is measured by a throttle valve 3 and sucked into a cylinder through an intake valve 4.
[0026]
Each cylinder of the engine 1 is provided with an electromagnetic fuel injection valve 5 for injecting fuel (gasoline) directly into the combustion chamber, and an air-fuel mixture is formed in the cylinder by the fuel injected from the fuel injection valve 5. Is done. The air-fuel mixture in the cylinder is ignited and burned by spark ignition by the spark plug 6, and the combustion exhaust is discharged through the exhaust valve 7, purified by the catalyst 8, and released into the atmosphere.
[0027]
Although the engine 1 in the present embodiment constitutes a direct injection spark ignition engine with the above configuration, the fuel injection valve 5 may be a port injection spark ignition engine in which fuel is injected into an intake port portion. A control unit 10 incorporating a microcomputer controls fuel injection by the fuel injection valve 5 and ignition by the ignition plug 6 (energization to an ignition coil not shown) by arithmetic processing based on detection signals from various sensors.
[0028]
The various sensors include an air flow meter 11 that detects the intake air flow rate Q, a position sensor 12 that outputs a position signal POS for each 1 ° CA, and a reference sensor that outputs a reference signal (reference angle signal) REF for each reference crank angle. 13, 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 water temperature sensor 17 for detecting the cooling water temperature TwA boost sensor 18 (suction negative pressure detecting means) that detects the boost (suction negative pressure) of the engine 1 as an absolute pressure with zero vacuum.Etc. are provided.
[0029]
The control unit 10 calculates the engine rotational speed Ne based on the position signal POS or the reference signal REF, and the function as the rotational speed detecting means functions as the position sensor 12 or the reference sensor 13 and the control unit 10. And realized by. 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) that is opened and closed by an actuator such as a step motor so that the opening degree can be controlled. The control unit 10 controls the amount of auxiliary air supplied to the engine via the bypass passage 21 by controlling the opening degree of the auxiliary air amount control valve 22.
[0030]
Auxiliary air amount control valve twenty two Downstream bypass passage twenty one In addition, a cut valve that is opened and closed on and off twenty three This cut valve is interposed twenty three Is a boost sensor as shown in FIG. 18 The signal of the control unit Ten By processing with the logic circuit provided in the Opening / closing (energization / non-energization) is controlled based on the output of the circuit. That is, boost sensor 18 It is controlled to be either an open state or a closed state based on the boost detected in (1), and is controlled not by software processing but by a logic circuit in order to increase control reliability.
[0031]
The control unit 10 calculates the basic fuel injection amount Tp based on the intake air flow rate Q detected by the air flow meter 11 and the engine rotational speed Ne calculated based on the position signal POS or the reference signal REF. 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. The fuel supply to the engine 1 is controlled by outputting 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.
[0032]
Further, the control unit 10 controls the fuel injection by the fuel injection valve 5 to stop when the throttle valve 3 is fully closed and the engine rotational speed Ne is a deceleration operation at a predetermined speed or higher (predetermined driven operation state). (Hereinafter referred to as deceleration fuel cut) is performed to reduce HC emissions and improve fuel efficiency (fuel cut means). However, if the fuel cut is executed while the temperature of the catalyst 8 is high, the catalyst 8 will be deteriorated. Therefore, the deceleration fuel cut is prohibited when the temperature of the catalyst 8 is equal to or higher than a predetermined temperature. (Fuel cut prohibition means).
[0033]
Then, in the 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. 3 to control the air amount during the deceleration operation with combustion. is doing. In the flowchart of FIG. 3, in step 1 (denoted as S1 in the figure, the same applies hereinafter), it is determined whether or not a deceleration fuel cut condition is satisfied.
[0034]
If the deceleration fuel cut condition is satisfied, the process proceeds to step 2 to determine whether or not the deceleration fuel cut should be prohibited based on the temperature of the catalyst 8. The temperature of the catalyst 8 may be directly detected by a temperature sensor, or may be estimated from the engine load, the engine rotational speed Ne, etc. (catalyst temperature detecting means).
[0035]
When the conditions are such that the catalyst temperature is low and deceleration fuel cut can be executed, the routine proceeds to step 3 where deceleration fuel cut is executed. On the other hand, when the catalyst temperature is high and deceleration fuel cut is prohibited, fuel injection is normally performed. However, when the throttle valve 3 is fully closed, the negative pressure becomes high and the amount of air becomes insufficient and misfire occurs. Therefore, the amount of air is controlled by the auxiliary air amount control valve 22.
[0036]
Specifically, the process proceeds to step 4 and a table in which the target auxiliary air amount is stored in advance corresponding to the engine rotational speed Ne is referred to, and the target auxiliary air amount corresponding to the engine rotational speed Ne at that time is searched. (Target auxiliary air amount setting means). The target auxiliary air amount is set to a larger value as the engine rotational speed Ne is higher. Accordingly, the target auxiliary air amount can be controlled to an appropriate auxiliary air amount corresponding to a difference in required air amount that varies depending on the engine rotational speed Ne. .
[0037]
That is, as shown in FIG. 4, the target auxiliary air amount corresponding to the engine rotational speed Ne is obtained as a target boost (absolute pressure) between a misfire limit boost and a boost equivalent to N / L (no load). As a result of the preset value, the higher the engine rotational speed Ne, the larger the value is set. As a result, the amount of air is prevented from accelerating while avoiding misfire. Can be controlled.
[0038]
Steps 1 and 2 correspond to an operation state detection means for detecting a deceleration operation (driven operation) accompanied by combustion. In step 5, the opening degree of the auxiliary air amount control valve 22 is controlled to an opening degree at which the target auxiliary air amount set in step 4 is obtained (air amount control means, auxiliary air amount control means).
[0039]
In step 6, the fuel cut is prohibited in response to the determination result in step 2 (fuel cut prohibiting means), and combustion is performed in a state where the auxiliary air amount is obtained via the auxiliary air amount control valve 22.
[0040]
Where the cut valve twenty three Is controlled to open when it is below the no-load N / L equivalent boost (absolute pressure) shown in FIG. 4 and below the reference boost set above the target boost during deceleration, and closes when the reference boost is exceeded. As a result, the bypass passage opens immediately after shifting to the deceleration operation. twenty one The supplementary air amount can be supplied through the air. According to this configuration, the auxiliary air amount control valve twenty two Even if there is an open failure, it can be avoided that the auxiliary air amount is supplied except during deceleration.
[0041]
The flowchart of FIG. 5 shows a second embodiment of air amount control during deceleration operation with combustion.Figure5In step 11, in step 11, it is determined whether or not the deceleration fuel cut condition is satisfied. When the condition is satisfied, in step 12, the deceleration fuel cut should be prohibited based on the temperature of the catalyst 8. It is determined whether or not there is.
[0042]
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, when the temperature of the catalyst 8 is high and it is a condition that the deceleration fuel cut should be prohibited, the process proceeds to step 14 and the target auxiliary air amount is set based on the engine rotational speed Ne as in step 4 (target auxiliary air). Quantity setting means).
[0043]
In step 15, the boost PB detected by the boost sensor 18 (absolute pressure with zero vacuum) is read. In step 16, a deviation ΔPB between the boost PBTG targeted in setting the target auxiliary air amount based on the engine speed Ne and the detected actual boost PB is calculated (ΔPB = PBTG−PB).
[0044]
In step 17, a correction air amount HOS corresponding to the deviation ΔPB calculated in step 16 is obtained by referring to a table in which the correction air amount HOS is stored in advance according to the deviation ΔPB.
[0045]
In the table of the correction air amount HOS in the step 17, the absolute value of the correction amount HOS increases as the absolute value of the deviation ΔPB increases, and the deviation ΔPB is positive and the actual boost PB is the target boost PBTG. When the value 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. Thus, 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 is like that.
[0046]
That is, by correcting the target auxiliary air amount by the correction amount HOS, the auxiliary air amount that can obtain the target boost PBTG can be set with high accuracy even if there is a change in atmospheric pressure or the like.
[0047]
When the correction amount HOS is set in step 17, the correction is performed by adding the correction amount HOS to the target auxiliary air amount set in step 14 in step 18, and in step 19, based on the corrected target auxiliary air amount. Then, the opening degree of the auxiliary air amount control valve 22 is controlled. In step 20, deceleration fuel cut is prohibited, and combustion is performed in a state where an auxiliary air amount is obtained as a result of the opening degree control in step 19 described above.
[0048]
Again, the cut valve twenty three Is controlled to open when it is below the no-load N / L equivalent boost (absolute pressure) shown in FIG. 4 and below the reference boost set above the target boost during deceleration, and closes when the reference boost is exceeded. Controlled.
[0049]
Figure6This flowchart shows the state of the auxiliary air amount control in the third embodiment. Figure6In step 31, the deceleration fuel cut condition is determined in step 31, and when the condition is satisfied, the process proceeds to step 32 to determine whether or not the fuel cut should be prohibited based on the catalyst temperature.
[0050]
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 deceleration fuel cut should be prohibited, the process proceeds to step 34, and the target auxiliary air amount is set according to the engine rotational speed Ne as in steps 4 and 14.
[0051]
In step 35, it is determined whether or not a misfire has occurred in the engine 1. Detection of misfire can be detected based on fluctuations in the engine rotational speed Ne, and if an in-cylinder pressure sensor is provided, it can be detected based on the in-cylinder pressure detected by the sensor (misfire detection means).
[0052]
When it is determined in step 35 that misfire has occurred, the process proceeds to step 36, the correction air amount HOS is increased by a predetermined value Δα1, and when it is determined that no misfire has occurred, the process proceeds to step 37, where The correction air amount HOS is decreased by a predetermined value Δα2 (<Δα1).
[0053]
That is, when misfire has occurred, the amount of air is judged to be insufficient, and the amount of auxiliary air is increased. On the other hand, when there is no misfire, the amount of auxiliary air is decreased to avoid acceleration due to excessive supply of air. It is.
[0054]
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 limit values of the auxiliary air amount are set based on the engine speed Ne. The upper and lower limit values are set corresponding to the no-load / misfire limit boost shown in FIG.
[0055]
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 limit values set in step 39. When it is determined in step 40 that the target auxiliary air amount is within the range between the upper and lower limits, the process proceeds to step 41, where the auxiliary air amount control valve 22 is controlled according to the target auxiliary air amount, and in step 42, the deceleration is performed. Process to prohibit fuel cut.
[0056]
On the other hand, when it is determined in step 40 that the target auxiliary air amount exceeds the range sandwiched between the upper and lower limits, the process proceeds to step 43 to execute a deceleration fuel cut (fuel cut forcing means by the 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 a failure of the auxiliary air amount control valve 22, and combustion occurs in a state where misfire occurs or acceleration occurs. May have been done.
[0057]
When misfire occurs, unburned HC may burn in the catalyst 8 and cause melting of the catalyst 8, and if acceleration occurs, the operability is greatly impaired. This should be dealt with preferentially over the progress of catalyst degradation due to execution. Therefore, a deceleration fuel cut is executed so as to avoid a deceleration operation in a state where at least misfire and acceleration occur.
[0058]
When it is determined in step 40 that the target auxiliary air amount exceeds the range sandwiched between the upper and lower limits, until the ignition switch is turned off, even if the catalyst temperature is high. It is better not to prohibit the deceleration fuel cut.
[0059]
Again, the cut valve twenty three Is controlled to open when it is below the no-load N / L equivalent boost (absolute pressure) shown in FIG. 4 and below the reference boost set above the target boost during deceleration, and closes when the reference boost is exceeded. Controlled.
[0060]
Figure7This flowchart shows the state of the auxiliary air amount control in the fourth embodiment. Figure7In step 51, the deceleration fuel cut condition is determined in step 51. When the condition is satisfied, the process proceeds to step 52, and 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.
[0061]
On the other hand, when the catalyst temperature is high and the deceleration fuel cut should be prohibited, the routine proceeds to step 54, and the target auxiliary air amount is set according to the engine rotational speed Ne as in steps 4, 14, and 34. 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 increase change.
[0062]
Then, when the vehicle speed VSP is increasing, in other words, when the vehicle is accelerating, it is a step to surely avoid the acceleration at the time of the deceleration request under the condition that the deceleration fuel cut should be prohibited. Proceed to 53 to execute a deceleration fuel cut. On the other hand, if it is determined that the vehicle speed VSP has not increased, the routine proceeds to step 56 where the change ΔNe (ΔNe = latest speed−previous speed) of the engine rotation speed Ne is equal to or greater than a predetermined value and the engine rotation speed Ne increases. It is determined whether or not a change is indicated.
[0063]
Even when the engine rotational speed Ne is increasing and changing, the routine proceeds to step 53 to execute the deceleration fuel cut. The process from step 55 or step 56 to step 53 corresponds to acceleration fuel cut forcing means. When neither the vehicle speed VSP nor the engine speed Ne has increased, 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 air-fuel ratio controllability is lowered and there is a possibility that misfire or the like may occur. Therefore, the routine proceeds to step 53, where the deceleration fuel cut is executed.
[0064]
When neither the vehicle speed VSP nor the engine rotational speed Ne has increased and the basic fuel injection amount Tp is not less than the minimum value, the routine proceeds to step 58, where the auxiliary air amount control valve 22 is controlled according to the target auxiliary air amount. In step 59, deceleration fuel cut is prohibited.
[0065]
In the fourth embodiment, the target auxiliary air amount is determined based only on the engine rotational speed Ne. However, as in the second embodiment, the engine rotational speed Ne and the boost sensor 18 are determined. In the configuration in which the target auxiliary air amount is determined based on the detection result of the above, or in the configuration in which the target auxiliary air amount is determined from the engine rotational speed Ne and the result of misfire detection as in the third embodiment, the same as above. Further, a configuration may be adopted in which the deceleration fuel cut is executed based on the change in the vehicle speed VSP, the engine rotational speed Ne, and the basic fuel injection amount Tp.
[0066]
Again, the cut valve twenty three Is controlled to open when it is below the no-load N / L equivalent boost (absolute pressure) shown in FIG. 4 and below the reference boost set above the target boost during deceleration, and closes when the reference boost is exceeded. Controlled.
[0067]
The flowchart of FIG. 8 shows the state of the auxiliary air amount control in the fifth embodiment. This FIG.In step 61, in step 61, it is determined whether or not the temperature of the catalyst 8 is a predetermined high temperature state in which deceleration fuel cut should be prohibited.
[0068]
When the catalyst temperature is high, the routine proceeds to step 62, where the target auxiliary air amount is set to the engine in the same manner as in the first embodiment in order to cope with the deceleration operation in which fuel cut is prohibited without waiting for the deceleration operation. In step 63, the opening degree of the auxiliary air amount control valve 22 is opened corresponding to the target auxiliary air amount.
[0069]
In step 64, the deceleration fuel cut condition is determined. When the condition is satisfied, the process proceeds to step 65, and 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 66, where the deceleration fuel cut is executed.
[0070]
On the other hand, when the catalyst temperature is high and it is a condition that the deceleration fuel cut should be prohibited, the process proceeds to step 67 and the deceleration fuel cut is prohibited. At this time, since the cut valve 23 is controlled to open with a decrease in boost due to the shift to the deceleration operation, the auxiliary air amount adjusted by the auxiliary air amount control valve 22 opened in advance is immediately supplied to the engine. .
[0071]
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 the response delay of the opening degree change. When it is predicted to be performed, the opening of the auxiliary air amount control valve 22 is opened in advance to an opening corresponding to the target auxiliary air amount, and before the actual deceleration operation is performed, the auxiliary air amount is controlled by the cut valve 23. If the cut valve 23 is opened with the shift to the deceleration operation while the supply is cut off, the response of the cut valve 23 that opens and closes on / off is good, so the target auxiliary air amount immediately after the shift to the deceleration operation Can be supplied.
[0072]
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 detection result of misfire, and the corrected target auxiliary air amount falls within a predetermined range. It is also possible to adopt a configuration in which the fuel is shifted to the fuel cut when exceeding, or the fuel cut is shifted when acceleration is detected, which will be described later.6th and 7thThe same applies to the embodiments.
[0073]
Figure9The flowchart ofA sixth embodiment will be described.This figure9In step 71, in step 71, it is determined whether or not the temperature of the catalyst 8 is a predetermined high temperature state in which deceleration fuel cut should be prohibited. When the catalyst temperature is high, the process proceeds to step 72 and waits for deceleration operation. Instead, a target auxiliary air amount is set to cope with a deceleration operation in which fuel cut is prohibited, and in step 73, the opening degree of the auxiliary air amount control valve 22 is opened corresponding to the target auxiliary air amount.
[0074]
In step 74, it is determined whether or not the throttle valve 3 is fully closed. When the throttle valve 3 is in the open state, the routine proceeds to step 75 where the cut valve 23 is controlled to be closed in preference to the open / close control of the cut valve 23 corresponding to the boost detected by the boost sensor 18. To do. Thus, the auxiliary air amount is prevented from being supplied to the engine 1 through the auxiliary air amount control valve 22 in the traveling state in which the throttle valve 3 is opened. That is, in the present embodiment, as described above, the auxiliary air amount control valve 22 is opened in advance to meet the request for deceleration before the deceleration operation, but the throttle 3 is opened. In this state, if the auxiliary air is supplied, torque fluctuation occurs and the driver feels uncomfortable. To avoid this, when the throttle valve 3 is open, it is related to the boost at that time. First, the cut valve 23 is closed.
[0075]
On the other hand, when the throttle valve 3 is fully closed, the routine proceeds to step 76, where a deceleration fuel cut condition other than the throttle valve 3 is fully closed is determined, and when the condition is established, the routine proceeds to step 77, where fuel cut is prohibited based on the catalyst temperature. It is determined whether or not it is a power state. 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.
[0076]
On the other hand, when the catalyst temperature is high and the deceleration fuel cut should be prohibited, the process proceeds to step 79, and the deceleration fuel cut is prohibited. At this time, the cut valve 18 is controlled to open as the boost decreases due to the shift to the deceleration operation. Figure10The flowchart of7th Embodiment is shown.
[0077]
This figure10In step 81, in step 81, it is determined whether or not the temperature of the catalyst 8 is a predetermined high temperature state in which deceleration fuel cut should be prohibited. If the catalyst temperature is high, the process proceeds to step 82, where deceleration operation is waited. Instead, the target auxiliary air amount is set to cope with the deceleration operation in which fuel cut is prohibited, and in step 84, the opening degree of the auxiliary air amount control valve 22 is opened corresponding to the target auxiliary air amount.
[0078]
In step 84, it is determined whether or not the throttle valve 3 is fully closed. When the throttle valve 3 is in the open state, the routine proceeds to step 85 where the cut valve 23 is controlled to be closed in preference to the open / close control of the cut valve 23 corresponding to the boost detected by the boost sensor 18. To do. On the other hand, when the throttle valve 3 is fully closed, the routine proceeds to step 86, where a deceleration fuel cut condition other than the throttle valve 3 is fully closed is determined, and when the condition is satisfied, the routine proceeds to step 87, where fuel cut is prohibited based on the catalyst temperature. It is determined whether or not it is a power state.
[0079]
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 deceleration fuel cut should be prohibited, the process proceeds to step 89, and the deviation between the opening of the auxiliary air amount control valve 22 and the target opening (deviation = actual opening-target opening). Is determined to be within a predetermined range.
[0080]
Specifically, it is determined whether or not the deviation is smaller than -D1 and the actual opening is smaller than a target opening by a predetermined value D1 or more. The D1 is a value corresponding to the deviation between the target boost corresponding to the target opening and the misfire limit boost. When the actual opening is smaller than the target opening and the deviation is equal to or greater than the predetermined value D1, the air amount It is judged that there is a possibility of misfire due to lack.
[0081]
Further, it is determined whether the deviation is larger than D2 and the actual opening is larger than a target opening by a predetermined value D2. The D1 is a value corresponding to a deviation between a target boost corresponding to the target opening and a no-load N / L boost. When the actual opening is larger than the target opening and the deviation is equal to or greater than a predetermined value D2, It is judged that there is a possibility of acceleration due to excessive air volume.
[0082]
When the actual opening is smaller than the target opening by a predetermined value D1 or when the actual opening is larger than the target opening by a predetermined value D2, the air amount is excessive or insufficient even if the deceleration fuel cut is prohibited. Since there is a possibility that misfire or acceleration may occur due to the above, the routine proceeds to step 88, where a deceleration fuel cut is executed (fuel cut forcing means based on opening degree difference), although the catalyst temperature is high.
[0083]
On the other hand, when target opening-predetermined value D1 ≦ actual opening ≦ target opening + predetermined value D2, there is no excess or deficiency in the air amount that would cause misfire or acceleration. Is prohibited. According to such a configuration, it is determined that the catalyst temperature is high immediately before the deceleration fuel cut condition is satisfied, and the opening degree of the auxiliary air amount control valve 22 is controlled in advance to an opening degree corresponding to the target auxiliary air amount. If the target opening cannot be controlled before entering the operation, and the deviation between the target opening and the actual opening is a relatively large value that causes misfire and acceleration, Even if the deceleration fuel cut is prohibited, misfire and acceleration may occur in the initial state. Therefore, the deceleration fuel cut is executed as it is to prevent the occurrence of misfire and acceleration.
[0084]
The present invention is also applicable to an engine that includes a throttle valve whose opening degree is electrically controlled and does not have a passage that bypasses the throttle valve. That is, even in such an engine, when the engine output is not required (for example, when the accelerator depression amount by the driver is 0), the throttle valve opening is controlled to be substantially fully closed, and the engine speed at this time is The fuel is cut if the rotational speed is equal to or higher than the predetermined rotational speed. At this time, if both the fuel cut condition and the fuel cut prohibition condition based on the catalyst temperature are satisfied, a small opening degree set according to the engine rotational speed is established. It is only necessary to correct the increase in the throttle valve opening.
[Brief description of the drawings]
[Figure 1]The system block diagram of the engine which shows embodiment.
[Figure 2]The figure which shows the drive circuit of the cut valve in embodiment.
FIG. 3 is a flowchart showing the contents of auxiliary air amount control in the first embodiment.
FIG. 4 is a diagram illustrating a correlation between a no-load equivalent boost, a misfire limit boost, and a target boost.
[Figure 5]The flowchart which shows the content of auxiliary | assistant air amount control in 2nd Embodiment.
[Fig. 6]The flowchart which shows the content of auxiliary | assistant air amount control in 3rd Embodiment.
[Fig. 7]The flowchart which shows the content of the auxiliary | assistant air amount control in 4th Embodiment.
[Fig. 8]The flowchart which shows the content of the auxiliary | assistant air amount control in 5th Embodiment.
FIG. 9The flowchart which shows the content of auxiliary | assistant air amount control in 6th Embodiment.
FIG. 10The flowchart which shows the content of the auxiliary | assistant air amount control in 7th Embodiment.
[Explanation of symbols]
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 flow control valve
23 ... Cut valve

Claims (8)

An operating state detecting means for detecting the operating state of the engine;
Fuel cut means for stopping fuel supply to the engine when a predetermined driven operation state of the engine is detected by the operation state detection means;
Catalyst temperature detection means for detecting the temperature of the catalyst interposed in the exhaust passage of the engine;
Fuel cut prohibiting means for prohibiting fuel supply from being stopped by the fuel cut means when the catalyst temperature detected by the catalyst temperature detection means is equal to or higher than a predetermined value;
An auxiliary air amount control valve that 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;
A rotational speed detecting means for detecting the rotational speed of the engine;
Target auxiliary air amount setting means for setting the target auxiliary air amount supplied to the engine to be larger as the rotational speed detected by the rotational speed detecting means is higher;
Engine is a predetermined driven operating state, and, when the stop of the fuel cut prohibiting means thus fuel supply is prohibited, an auxiliary air amount supplied to the engine is set by the target air amount setting means Auxiliary air amount control means for controlling the auxiliary air amount control valve so as to achieve a target auxiliary air amount;
Including
An air amount control device for an engine, wherein a cut valve that opens when the engine is in the predetermined driven operation state according to an intake negative pressure of the engine is interposed in the bypass passage . When the catalyst temperature detected by the catalyst temperature detecting means is equal to or higher than the predetermined value, the auxiliary air amount control means sets the opening of the auxiliary air quantity control valve to a target opening corresponding to the target auxiliary air quantity. 2. The engine air amount control device according to claim 1 , wherein the air amount control device of the engine is controlled in advance every time. When the difference between the opening of the auxiliary air amount control valve and the target opening when the engine operating state shifts to the predetermined driven operating state is greater than or equal to a predetermined value, priority is given to the fuel cut prohibiting means. 3. An engine air amount control device according to claim 2, further comprising a fuel cut forcing means based on an opening difference for forcibly stopping fuel supply to the engine. The engine air amount control device according to any one of claims 1 to 3 , wherein the cut valve is held closed when the throttle valve is open in preference to the suction negative pressure state. Intake negative pressure detection means for detecting the intake negative pressure of the engine as an absolute pressure, and the target auxiliary air amount setting means sets the target auxiliary air amount in accordance with the detected rotational speed and intake negative pressure. The engine air quantity control device according to any one of claims 1 to 4 , wherein Comprising a misfire detecting means for detecting a misfire of the engine, the target assist air amount setting means, according to claim 1, wherein setting the target assist air amount in accordance with the presence or absence of the misfire detected rotational speed The air amount control device for an engine according to any one of the above. A fuel cut forcing means based on an auxiliary air amount forcibly stopping the fuel supply to the engine in preference to the fuel cut prohibiting means when the auxiliary air amount controlled by the auxiliary air amount control means exceeds a predetermined range; The engine air amount control device according to any one of claims 1 to 6 , wherein the engine air amount control device is provided. When an acceleration operation 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 fuel supply to the engine is forcibly stopped in preference to the fuel cut prohibition means. The engine air amount control device according to any one of claims 1 to 7 , further comprising an acceleration fuel cut forcing means.

Images