JP4421078B2 - In-cylinder injection engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus for an in-cylinder injection engine that performs uniform combustion or stratified combustion in accordance with an operating state, and more particularly, to a purge process of evaporated fuel (evaporation) in such an engine.
[Prior art]
Conventionally, an engine that directly injects fuel into a combustion chamber, that is, an in-cylinder injection engine is known. Generally, in this type of engine, either a stratified combustion mode or a uniform combustion mode is selectively executed depending on the operating state of the engine, for example, the engine speed and the engine load. For example, Japanese Patent Laid-Open No. 11-36998 discloses evaporation purge control that takes into account the combustion mode in a cylinder injection engine. Specifically, when switching from stoichiometric combustion (uniform combustion) conditions to lean combustion (stratified combustion) conditions, the release of evaporation to the intake system is temporarily prohibited and then a predetermined time (delay time) After elapses, switch to lean combustion. This prevents deterioration in combustibility when switching from stoichiometric combustion to lean combustion.
[0002]
In JP-A-11-36921, when it is judged that the amount of evaporation is large and the evaporation purge has a large effect on stratified combustion, operation by stratified combustion is prohibited and operation by uniform combustion is continued. Techniques to do this are disclosed. This avoids a decrease in operability and the occurrence of exhaust smoke, which are problems when performing stratified combustion while purging the evaporation.
[0003]
[Problems to be solved by the invention]
In the technique disclosed in Japanese Patent Application Laid-Open No. 11-36998, when the operating state is switched from the uniform combustion condition to the stratified combustion condition, regardless of the amount of evaporation generated or the amount introduced, the amount corresponding to the delay time is uniform. The switch to stratified combustion is delayed. As a result, there is a problem that the operation region in the stratified combustion is substantially reduced, and the fuel consumption is lowered accordingly.
[0004]
This technique also relates to switching from uniform combustion to stratified combustion. Therefore, there is no disclosure regarding switching from stratified combustion to uniform combustion, and no mention is made of problems associated with this switching.
[0005]
Accordingly, an object of the present invention is to improve the drivability by preventing combustion fluctuations and deterioration of combustibility when switching from uniform combustion to stratified combustion, and to substantially reduce the operating range in stratified combustion. This is to further improve the fuel consumption.
[0006]
Another object of the present invention is to improve drivability by preventing combustion fluctuations and deterioration of combustibility when switching from stratified combustion to uniform combustion.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, a first invention is provided in a purge passage in which an intake passage and a fuel tank are communicated with each other in a control apparatus for a cylinder injection engine that performs uniform combustion or stratified combustion according to an operating state. A control valve that adjusts the amount of evaporation purge to the intake passage, and a combustion mode of stratified combustion or uniform combustion is selected according to the operating state, and a control valve is selected according to the selected combustion mode. Control means for controlling. Here, the control means first prohibits the purge of the evaporation when the operation state in which the combustion mode is to be switched from the uniform combustion to the stratified combustion is large and the amount of generated evaporation is large. After the prohibition of purging continues for a predetermined time, switching from uniform combustion to stratified combustion is performed in a state where the inflow amount of the evaporation, which is a disturbance of the fuel injection amount by the injector, is sufficiently reduced.
[0008]
According to a second aspect of the present invention, there is provided an in-cylinder injection engine control apparatus that performs uniform combustion or stratified combustion in accordance with an operating state, and is provided in a purge passage that communicates an intake passage and a fuel tank. A control valve that adjusts the purge amount of the engine, and a control means that selects either a stratified combustion or a uniform combustion according to the operating state and controls the control valve according to the selected combustion Have. Here, the control means switches the combustion mode in a state in which the purge mode is temporarily prohibited when the combustion mode is switched from the stratified combustion to the uniform combustion when the amount of generated evaporation is large. . Thereby, the switching of the combustion mode is performed in a stable state without being affected by the evaporation that becomes a disturbance of the fuel injection amount by the injector. Then, after the prohibition of purge continues for a predetermined time, the evaporation purge is started.
[0009]
Here, in the first or second invention, when a sensor for detecting the hydrocarbon concentration is further provided in the purge passage or the canister, and the hydrocarbon concentration detected by the sensor is higher than a predetermined value In addition, the control means preferably determines that the amount of evaporation generated is large.
[0010]
In the first or second aspect of the invention, a sensor for detecting the pressure in the fuel tank is further provided, and when the pressure detected by the sensor is higher than a predetermined value, the control means generates a large amount of evaporation. You may judge.
[0011]
In the first or second aspect of the invention, a sensor for detecting the fuel temperature in the fuel tank is further provided, and when the fuel temperature detected by the sensor is higher than a predetermined value, the control means You may judge that there are many.
[0012]
Further, in the first or second invention, a sensor provided in the exhaust passage for detecting the exhaust air / fuel ratio is further provided, and the control means is based on a deviation between the exhaust air / fuel ratio detected by the sensor and the target air / fuel ratio. May determine the amount of evaporation generated.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall configuration diagram showing an example of a direct injection engine to which the present invention is applicable. The in-cylinder injection engine 1 directly injects fuel into the cylinder and burns the air-fuel mixture by spark ignition. Each intake port of the engine 1 is provided with an intake valve 2, and these intake ports communicate with an intake manifold 3. Each exhaust port of the engine 1 is provided with an exhaust valve 4, and these exhaust ports communicate with the exhaust manifold 5. In addition, a discharge electrode of a spark plug 6 that ignites an air-fuel mixture in the combustion chamber faces an upper center of the combustion chamber in each cylinder of the engine 1. In the vicinity of the intake valve 2 in the combustion chamber, an injector 7 that directly injects fuel (gasoline) into the combustion chamber is provided. In general, in-cylinder injection engine 1, it is necessary to make fuel spray finer due to demands on combustion characteristics. Therefore, the fuel stored in the fuel tank 18 is increased to a prescribed pressure and supplied to the injector 7 via a fuel pipe (not shown).
[0014]
An air cleaner 8 provided in the intake passage is connected to an air chamber 9 communicating with the intake manifold 3. An electric throttle valve 10 for adjusting the intake air amount is interposed between the air cleaner 8 and the air chamber 9. The throttle valve 10 is operated by an electric motor 11 and is not mechanically linked to the accelerator pedal 30. The opening degree of the throttle valve 10 (hereinafter referred to as “throttle opening degree”) is set by an output signal from a control device 12 (hereinafter referred to as “ECU”) mainly composed of a microcomputer. The negative pressure (intake negative pressure) in the air chamber 9 located downstream of the throttle valve 10 changes according to the throttle opening.
[0015]
On the other hand, the exhaust manifold 5 communicates with the three-way catalytic converter 13 through an exhaust passage, and a NOx storage catalytic converter 14 is provided downstream thereof. An exhaust gas recirculation passage 16 is provided between the exhaust manifold 5 and the air chamber 9. The exhaust gas recirculation passage 16 is provided with an exhaust gas recirculation valve 17 (EGR valve) for adjusting the amount of exhaust gas recirculated to the intake air passage.
[0016]
The upper portion of the fuel tank 18 communicates with the air chamber 9 via a purge passage 19 for releasing the evaporation generated in the fuel tank 18 and the like. The purge passage 19 is provided with a canister 20 and a purge control valve 21. The canister 20 has an adsorption portion made of activated carbon or the like that adsorbs the evaporation, and a fresh air inlet for introducing the atmosphere is provided below the canister 20. The purge control valve 21 employed in this embodiment is a duty solenoid valve controlled by the ECU 12, but an appropriate one such as a linear solenoid valve or a step motor type may be employed.
[0017]
Sensor signals from various sensors including the sensors 22 to 29 are input to the ECU 12 configured mainly with a microcomputer. The fuel tank internal pressure sensor 22 is provided in the upper part of the fuel tank 18, and the pressure Pf in the tank 18 is detected based on this sensor signal. The fuel temperature sensor 23 is provided in the fuel tank 18, and the fuel temperature Tf is detected based on the sensor signal. The fuel temperature sensor 23 may be provided in a fuel pipe (not shown) that supplies fuel to the injector 7. The HC sensor 24 is provided in the purge passage 19, and the concentration of hydrocarbon HC in the purge passage 19 is detected based on the sensor signal. Thereby, the evaporation concentration De in the purge passage 19 is specified. The HC sensor 24 may be provided in the canister 20 instead of the purge passage 19. The throttle opening sensor 25 and the accelerator opening sensor 29 are sensors that respectively specify the throttle opening θt and the accelerator opening θa (corresponding to the depression amount of the accelerator pedal 30). The engine speed sensor 26 is a sensor for calculating the engine speed Ne. For example, a crank angle sensor that generates an output pulse every time the crankshaft rotates by a predetermined angle can be used. The engine coolant temperature sensor 27 is a sensor for specifying the coolant temperature Te of the engine coolant, and faces the coolant passage of the engine 1.
[0018]
Further, the air-fuel ratio sensor 28 is a sensor for detecting the actual air-fuel ratio A / F (exhaust air-fuel ratio) from the exhaust gas flowing through the exhaust passage, and for example, a linear O2 sensor can be used. Originally, the exhaust air-fuel ratio A / F calculated from the output signal of the air-fuel ratio sensor 28 is equivalent to the target air-fuel ratio when evaporation purge and EGR are not performed (ignoring blow-by gas). However, the actual air-fuel ratio does not match the target air-fuel ratio due to disturbance factors such as evaporation purge, exhaust gas inflow or secular change. Therefore, the deviation between the actual air-fuel ratio and the target air-fuel ratio is corrected by performing air-fuel ratio feedback control.
[0019]
The ECU 12 calculates the fuel injection amount, the fuel injection timing, the ignition timing, and the like according to the control program stored in the ROM based on the current operating state detected from various sensors, and performs the operation on the injector 7 and the spark plug 6. Output a control signal. Further, the ECU 12 outputs an instruction value to the electric motor 11 in order to secure the intake air amount necessary for combustion, and also instructs the EGR valve 17 to insure an appropriate exhaust gas recirculation amount. Is output. Furthermore, the ECU 12 controls the opening degree of the purge control valve 21 by outputting an instruction value DUTY that defines the duty ratio to the purge control valve 21.
[0020]
FIG. 2 is a flowchart of a control routine according to the present embodiment. The ECU 12 repeatedly executes this control routine at a predetermined interval (for example, 10 ms). In principle, the combustion mode is determined by referring to the combustion mode determination map shown in FIG. 3 from the current operating state. First, in step 1, parameters such as the evaporation concentration De, the engine speed Ne, and the accelerator opening degree θa are read as sensor information.
[0021]
Next, it is determined from the current operating state whether or not the following stratified combustion condition is satisfied (step 2).
(Stratified combustion conditions)
Condition 1: Te ≧ Teth
Condition 2: map (θa, Ne) = stratified combustion region
[0022]
From the above condition 1, when the engine water temperature Te is lower than the predetermined threshold value Teth, it is determined that the engine is in a cold state or in the process of warming up, and it is uniform without referring to the determination map of FIG. Combustion takes place. When the engine coolant temperature Te is equal to or higher than the threshold value Teth, it is determined whether or not the reference result of the determination map is the stratified combustion region (condition 2). That is, it is determined in which combustion region the operation state specified from the engine speed Ne and the accelerator opening θa corresponding to the required output of the engine is included. As can be seen from the figure, the low-load low-rotation state belongs to the stratified combustion region, and the other operating states belong to the uniform combustion (uniform mixed combustion) region. If the engine has been warmed up and is in the stratified combustion region, the stratified combustion condition is satisfied.
[0023]
When an affirmative determination is made in step 2, that is, when the stratified combustion condition is in an operating state, the routine proceeds to step 3 where it is determined whether or not the combustion mode instruction flag FMODE is “1”. The contents of instruction of this flag FMODE are as follows.
(Instruction contents of combustion mode instruction flag FMODE)
FMODE instruction contents
"1" Stratified combustion instruction
"2" Uniform combustion instruction
[0024]
When the instruction flag FMODE is set to “1”, stratified combustion is executed according to a combustion control routine that is a separate routine. Here, the stratified combustion is a combustion system in which fuel injection by the injector 7 is started in the compression stroke, is terminated immediately before ignition, and the rear end portion of the fuel spray is ignited by the spark plug 6 to burn the air-fuel mixture. Stratified combustion uses only air around the fuel and can obtain stable combustion with a very small amount of fuel with respect to the amount of charged air, and is therefore suitable for engine low load and low speed operation. Note that the evaporation purge is not performed during stratified combustion. This is because if the evaporation is purged during stratified combustion, the concentration of the combustible mixture in the vicinity of the ignition plug 6 may fluctuate greatly due to the effect of the evaporation, and the ignition may become unstable. This is because it may be discharged as it is.
[0025]
On the other hand, when the instruction flag FMODE is set to “2”, uniform combustion is executed according to the combustion control routine. Here, in the uniform combustion (also referred to as uniform mixed combustion), the fuel is injected at a time earlier than the stratified combustion (for example, at the end of the exhaust stroke or the intake stroke), and the injected fuel is sufficiently diffused into the cylinder, and the injected fuel It is a combustion system that ignites after uniformly mixing air and air. Uniform combustion is suitable for high-load high-speed operation because the air utilization rate is high and the engine output can be improved. Normally, evaporation purge is performed in accordance with the operating state during uniform combustion. Uniform combustion has a lower air-fuel ratio than stratified combustion, and the influence of purged evaporation on combustibility is relatively small, so that sufficient processing capacity for evaporation purge can be ensured. However, when a purge prohibition flag PPF, which will be described later, is set to “1”, evaporation purge is prohibited regardless of the operating state.
[0026]
When the instruction flag FMODE is switched from “1” to “2”, transition control is performed to switch the combustion mode from stratified combustion to uniform combustion. Further, when the instruction flag FMODE is switched from “2” to “1”, transition control for switching the combustion mode from uniform combustion to stratified combustion is performed. In these transition controls, it is necessary to accurately control the air-fuel ratio in order to prevent deterioration in drivability and combustion.
[0027]
If the determination in step 3 is affirmative, that is, if the stratified combustion condition is satisfied and stratified combustion is being executed (FMODE = “1”), the instruction flag FMODE is “1” in step 10. Therefore, the stratified combustion is continued. In this case, a purge prohibition flag PPF and a counter value CT described later are held at “0” (step 9).
[0028]
As described above, as long as the operation state having the stratified combustion region condition is maintained, the series of steps 1 to 3, 9, and 10 are repeated, so that the stratified combustion is continued.
[0029]
On the other hand, when the operation state that does not have the stratified combustion condition, that is, the operation state in the uniform combustion region is maintained, the series of steps 1, 2, 11, 16, and 17 are repeated, and the instruction flag FMODE Is held at “2”. Therefore, uniform combustion is continuously performed. In this case, in step 16, the purge prohibition flag PPF and the counter value CT are held at “0”.
[0030]
(Transition from uniform combustion to stratified combustion)
Next, control when the operating state shifts from the uniform combustion region to the stratified combustion region will be described. In this case, since the stratified combustion condition is established by the transition of the operation state, the process proceeds to step 3 after an affirmative determination in step 2. In the execution cycle before shifting to the operating state, the instruction flag FMODE is “2”, that is, uniform combustion is being executed. Therefore, when the operating state is switched from the uniform combustion region to the stratified combustion region, the process proceeds to step 4 through a negative determination in step 3.
[0031]
In step 4, it is determined whether or not the evaporation concentration De is equal to or greater than a predetermined determination value Deth1. This determination value Deth1 is a reference for determining whether or not the generated evaporation has a great influence on the combustibility. If a negative determination is made in step 4, that is, if it is determined that the evaporation concentration De is low, the process proceeds to step 10 via step 9. As a result, the instruction flag FMODE is set from “2” to “1” simultaneously with the transition of the operation state, so that the combustion mode is switched from uniform combustion to stratified combustion.
[0032]
In this way, when the evaporation concentration De is low, the concentration of the combustible air-fuel mixture in the vicinity of the ignition plug 6 does not vary greatly. Therefore, in this case, switching to stratified combustion is performed simultaneously with the transition of the operating state without providing a delay time as set in the prior art. Thereby, it can prevent that the driving | running area | region in stratified combustion reduces substantially, and can suppress the fall of a fuel consumption.
[0033]
On the other hand, if an affirmative determination is made in step 4, that is, if it is determined that the evaporation concentration De is high, the process proceeds to step 5 to determine whether or not the counter value CT has reached a predetermined upper limit value CT1. Since the initial value of the counter value CT is 0, in the execution cycle immediately after the transition of the operation state, the process proceeds to step 6 and the purge prohibition flag PPF is set from “0” to “1”. During the period in which the purge prohibition flag PPF is set to “1”, the evaporative purge is prohibited regardless of the operation state, so that the purge control valve 21 is fully closed. In step 7, the instruction flag FMODE is set to “2”. Therefore, even when the operation state shifts to the operation state where the stratified combustion condition is satisfied, the uniform combustion is continued. Finally, in step 8, the predetermined value α is incremented to the counter value CT (initial value is 0), and this routine in the current execution cycle ends.
[0034]
Thereafter, until the counter value CT reaches the upper limit value CT1, a series of steps 1 to 8 are repeated, and uniform combustion is continued in a state where the evaporation purge is prohibited (PPF = “1”) ( FMODE = “2”). At the same time, the counter value CT is incremented by a predetermined value α.
[0035]
Eventually, when the counter value CT reaches the upper limit value CT1, the determination result of step 5 in the execution cycle changes from positive to negative. As a result, the instruction flag FMODE is switched from “2” to “1”, so that the combustion mode is switched from uniform combustion to stratified combustion (step 10). At the same time, the purge prohibition flag PPF and the counter value CT are reset to “0”.
[0036]
Thus, when switching from uniform combustion to stratified combustion, if the evaporation concentration De is high, the concentration of the combustible air-fuel mixture in the vicinity of the ignition plug 6 may greatly vary due to the purged evaporation. Therefore, first, after evaporative purging is prohibited, uniform combustion is executed even though the operating state is the stratified combustion region. Then, the purge prohibition time is counted by the counter value CT, and the uniform combustion is continued until the upper limit value CT1 is reached. As a result, the amount of fuel disturbance caused by evaporation decreases with time. Then, after a predetermined time has elapsed, that is, in a state where the amount of fuel disturbance is sufficiently reduced, the combustion mode is switched from uniform combustion to stratified combustion. Thus, by performing transition control in a stable state with little disturbance due to evaporation, combustion fluctuations and deterioration of combustion can be prevented, and deterioration of drivability when switching combustion modes can be suppressed.
[0037]
(Transition from stratified combustion to uniform combustion)
Next, control when the operating state shifts from the stratified combustion region to the uniform combustion region will be described. In this case, since the stratified combustion condition is not satisfied due to the transition of the operation state, the process proceeds to step 11 through a negative determination in step 2. In step 11, it is determined whether or not the instruction flag FMODE is “2” and the purge prohibition flag PPF is “0”. The purge prohibition flag PPF is initially set to “0”. When the purge prohibition flag PPF is set to “1” in step 14 described later, the evaporation purge is forcibly prohibited regardless of the operating state. In the execution cycle of this routine before the change of the operation region, the instruction flag FMODE is “1”, that is, stratified combustion is being executed (PPF = “0”). Therefore, when the operation state is switched from the stratified combustion region to the uniform combustion region, the process proceeds to step 12 through a negative determination in step 11.
[0038]
In step 12, it is determined whether or not the evaporation concentration De is greater than or equal to a predetermined determination value Deth2. This determination value Deth2 is a value serving as a reference for determining whether the generated evaporation has a great influence on the combustibility. If a negative determination is made in step 12, that is, if the evaporation concentration De is determined to be low, the process proceeds to step 17 after resetting the purge prohibition flag PPF and the counter value CT in step 16. As a result, the instruction flag FMODE is set from “1” to “2” simultaneously with the transition of the operating state, so that the combustion mode is switched from stratified combustion to uniform combustion. In this way, when the evaporation concentration De is low, the influence of the evaporation that is the amount of fuel disturbance is small, so even if switching to the uniform combustion at the same time as the transition of the operating state, there is no possibility that drivability will be reduced.
[0039]
On the other hand, when an affirmative determination is made in step 12, that is, when it is determined that the evaporation concentration De is high, the routine proceeds to step 13 where it is determined whether or not the counter value CT has reached a predetermined upper limit value CT2. Since the initial value of the counter value CT is 0, in the execution cycle immediately after the transition of the operating state, the determination from step 13 proceeds to step 14 and the purge prohibition flag PPF is set from “0” to “1”. . In step 15, the predetermined value β is incremented to the counter value CT (initial value is 0). Finally, in step 17, uniform combustion is performed by setting the instruction flag FMODE to “2”.
[0040]
Thereafter, in the period until the counter value CT reaches the upper limit value CT2, the series of steps 1, 2, 11 to 15, and 17 are repeated, and hence the evaporative purge is prohibited (PPF = “1”). . At the same time, the counter value CT is sequentially incremented by the predetermined value β.
[0041]
Eventually, when the counter value CT reaches the upper limit value CT2, the determination result of step 13 in the execution cycle changes from positive to negative. As a result, the purge prohibition flag PPF is switched from “1” to “0” (step 16), and the evaporation purge is started.
[0042]
Thus, when switching from stratified combustion to uniform combustion, if the evaporation concentration De is high, drivability may be reduced when switching the combustion mode due to the effect of purged evaporation. Therefore, first, switching to uniform combustion is performed in a state where evaporation purge is temporarily prohibited. Then, the prohibition of the evaporation purge is continued for the purge prohibition period set by the upper limit value CT2. As a result, the combustion mode can be shifted without being affected by evaporation. Then, after a predetermined time has elapsed, the evaporation purge is started in a state where the amount of fuel disturbance is sufficiently reduced. In this way, during the changeover of the combustion mode that is easily affected by the evaporation that becomes the disturbance of the fuel injection amount in the injector 7, the purge of the evaporation is temporarily prohibited. As a result, it is possible to prevent combustion fluctuation and deterioration of combustion at the time of switching the combustion mode, and to improve drivability.
[0043]
In the above-described embodiment, the evaporation concentration De is directly detected using the HC sensor 24. However, the present invention is not limited to this. For example, the evaporation concentration may be estimated using the following method.
[0044]
1. Determination based on fuel tank internal pressure Pf
As the amount of evaporation generated increases, the pressure Pf in the fuel tank 18 also increases. Therefore, it is possible to determine the amount of evaporation generated from the pressure Pf in the fuel tank 18. Specifically, when the pressure Pf detected by the fuel tank internal pressure sensor 22 is higher than a predetermined value, it is determined that the amount of evaporation generated is large.
[0045]
2. Judgment based on fuel temperature Tf
Since the evaporation generation amount tends to increase as the fuel temperature rises, the evaporation generation amount can be determined from the fuel temperature Tf. Specifically, when the fuel temperature Tf detected by the fuel temperature sensor 23 is higher than a predetermined value, it is determined that the amount of evaporation generated is large.
[0046]
3. Judgment based on exhaust air-fuel ratio A / F
The greater the amount of evaporation generated and the greater the purge amount, the greater the deviation between the exhaust air-fuel ratio and the target air-fuel ratio. Therefore, it is also possible to estimate the evaporation concentration based on these air-fuel ratio deviations. This point will be specifically described. First, in the air-fuel ratio feedback control, the fuel injection pulse width Ti corresponding to the fuel injection amount of the injector 7 is specified by the following equation.
[Expression 1]
Tp = K × Q / Ne
Ti = Tp × Φ × LAMBDA + Ts
[0047]
That is, the basic fuel injection pulse width Tp is calculated based on the engine speed Ne and the intake air amount Q. K is an injector characteristic correction constant. The fuel injection pulse width Ti is calculated based on the equivalence ratio Φ, the basic fuel injection pulse width Tp, and the like, which are air-fuel ratio control variables. Here, LAMBDA is an air-fuel ratio feedback correction coefficient, and the exhaust air-fuel ratio is controlled to converge to the target air-fuel ratio by appropriately setting this correction coefficient. Ts is an invalid injection pulse width determined by the battery voltage. The details of the equation are described in Japanese Patent Application Laid-Open No. 11-36968, so please refer to it if necessary.
[0048]
When trying to maintain a certain air-fuel ratio, the higher the purge concentration to be purged, the more the fuel injection amount of the injector 7 needs to be corrected to decrease, so the air-fuel ratio feedback correction coefficient LAMBDA becomes smaller than the original set value. Go. Therefore, assuming that there is no great change in disturbance factors such as the EGR amount and that the purge control valve 21 is open, the value of the air-fuel ratio feedback correction coefficient LAMBDA has a correlation with the evaporation concentration. In view of such a correlation, the purge concentration can be estimated from the air-fuel ratio feedback correction coefficient LAMBDA set in accordance with the deviation between the exhaust air-fuel ratio and the target air-fuel ratio.
[0049]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent combustion fluctuation and deterioration of combustibility when switching from uniform combustion to stratified combustion, improve drivability, and further improve fuel efficiency. Further, it is possible to prevent combustion fluctuation and deterioration of combustibility when switching from stratified combustion to uniform combustion, and to improve drivability.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a control system of a direct injection engine
FIG. 2 is a flowchart of a control routine according to the present embodiment.
FIG. 3 is an explanatory diagram of a combustion form determination map
[Explanation of symbols]
1 in-cylinder injection engine, 2 intake valve,
3 Intake manifold, 4 Exhaust valve,
5 Exhaust manifold, 6 Spark plug,
7 Injector, 8 Air cleaner,
9 Air chamber, 10 Electric throttle valve,
11 electric motor, 12 control unit (ECU),
13 Three-way catalytic converter, 14 NOx storage catalytic converter,
15 muffler, 16 exhaust recirculation passage,
17 exhaust recirculation (EGR) valve, 18 fuel tank,
19 purge passage, 20 canister,
21 Purge control valve, 22 Fuel tank internal pressure sensor,
23 Fuel temperature sensor, 24 HC sensor,
25 throttle opening sensor, 26 engine speed sensor,
27 engine water temperature sensor, 28 air-fuel ratio sensor,
29 Accelerator opening sensor, 30 Accelerator pedal

Claims (6)

In the in-cylinder injection engine control device that performs uniform combustion or stratified combustion according to the operating state,
A control valve that is provided in a purge passage communicating the intake passage and the fuel tank, and that adjusts the purge amount of the evaporation to the intake passage;
Control means for selecting either stratified combustion or uniform combustion according to the operating state, and controlling the control valve according to the selected combustion form,
When the control means is in an operation state where the combustion mode should be switched from uniform combustion to stratified combustion, when the amount of evaporation is large, the purge of the evaporation is prohibited, and after the prohibition of the purge continues for a predetermined time, A control apparatus for an in-cylinder injection engine, wherein switching from uniform combustion to stratified combustion is performed. In the in-cylinder injection engine control device that performs uniform combustion or stratified combustion according to the operating state,
A control valve that is provided in a purge passage communicating the intake passage and the fuel tank, and that adjusts the purge amount of the evaporation to the intake passage;
Control means for selecting either stratified combustion or uniform combustion according to the operating state, and controlling the control valve according to the selected combustion form,
When the control means is in an operation state in which the combustion mode should be switched from stratified combustion to uniform combustion, and when the amount of generated evaporation is large, the control unit performs switching of the combustion mode in a state where the purge of the evaporation is temporarily prohibited, A control apparatus for an in-cylinder injection engine, wherein evaporative purging is performed after the prohibition of purge continues for a predetermined time. A sensor provided in the purge passage or the canister for detecting the concentration of hydrocarbon;
The in-cylinder injection according to claim 1 or 2, wherein the control means determines that the amount of evaporation generated is large when the concentration of hydrocarbons detected by the sensor is higher than a predetermined value. Engine control device. A sensor for detecting the pressure in the fuel tank;
The in-cylinder injection engine control according to claim 1 or 2, wherein the control means determines that the amount of evaporation generated is large when the pressure detected by the sensor is higher than a predetermined value. apparatus. A sensor for detecting a fuel temperature in the fuel tank;
The in-cylinder injection engine according to claim 1 or 2, wherein the control means determines that the amount of evaporation is large when the fuel temperature detected by the sensor is higher than a predetermined value. Control device. A sensor provided in the exhaust passage for detecting the exhaust air-fuel ratio;
The in-cylinder injection engine according to claim 1 or 2, wherein the control means determines the amount of evaporation generated based on a deviation between an exhaust air-fuel ratio detected by the sensor and a target air-fuel ratio. Control device.

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