JP2001182630A - Control system of direct injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct injection engine which promotes fuel economy by efficiently utilizing purged evaporative emission. SOLUTION: This system comprises a control valve 21 provided in a purge passage 19 connecting an intake air passage and a fuel tank 18 to change inflow of evaporation fuel gas into the intake air passage according to degree of opening and a control unit 12 which selects either stratified charge combustion or homogeneous mixing combustion according to driving condition and controls degree of opening of the control valve 21 according to the selected combustion type. If the control unit 12 judges that concentration of evaporation fuel gas in the purging passage 19 is higher than the predetermined value, it selects homogeneous mixing combustion even when the driving condition is such that stratified charge combustion should be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a direct injection engine, and more particularly, to an evaporation purge control.

[0002]

2. Description of the Related Art Conventionally, an engine in which fuel is directly injected into a combustion chamber by an injector provided in the combustion chamber,
That is, a direct injection engine is known. Generally, in this type of engine, a combustion mode of either stratified combustion or homogeneous mixed combustion is selectively executed according to the operating state of the engine, for example, the engine speed and the engine load.

[0003] Regarding the evaporative purge control in such a direct injection engine, for example, Japanese Patent Application Laid-Open No. 4-194354 discloses that in order to improve the engine output, the evaporated fuel gas (evaporation) is supplied only when the engine load is large. The technique of supplying the inside is disclosed. Also, JP-A-11-36922
In order to suppress the influence of the evaporation, which is a disturbance factor of the air-fuel ratio, Japanese Patent Application Publication No. JP-A-2005-115122 discloses a technique in which the exhaust gas sensor measures the exhaust air-fuel ratio and controls the evaporation purge amount according to the air-fuel ratio.

[0004]

However, in these prior arts, the evaporative purge control and the setting of the combustion mode are performed without considering the evaporative concentration state. Therefore, when the evaporative purge is performed during the stratified charge combustion, even if the purge control valve is set to the target opening, it is difficult to secure a desired amount of purge (amount of evaporative inflow into the intake passage). May occur. During stratified combustion, which requires a large amount of intake air, the throttle opening is set to be larger than during uniform mixed combustion. Therefore, during stratified charge combustion, the negative pressure in the intake passage (intake negative pressure) tends to be shallow (if the purge environment is the same, the larger the intake negative pressure, the greater the purge amount). In addition, the evaporator purged during stratified combustion does not contribute much to combustion. This is because the air-fuel ratio of the air-fuel mixture into which the evaporation is mixed is thinner than the air-fuel ratio that allows the flame to propagate. Therefore, even if the evaporative purge is performed at the time of stratified charge combustion, improvement in fuel efficiency by the purge cannot be expected much.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a direct injection engine capable of further improving fuel efficiency by efficiently using a purged evaporator. To provide.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a control device for a direct injection engine, which is provided in a purge passage connecting an intake passage and a fuel tank, and is provided in accordance with an opening degree. A control valve that changes the amount of fuel vapor gas flowing into the intake passage; and a combustion mode of either stratified combustion or uniform mixed combustion depending on the operation state, and control according to the selected combustion mode. Control means for adjusting the opening of the valve. Here, when the control unit determines that the concentration of the evaporated fuel gas in the purge passage is higher than a predetermined value, the control unit selects the uniform mixed combustion even if the operation state is to perform the stratified combustion.

[0007] In the above configuration, it is preferable that the control means sets the opening degree of the control valve larger when uniform mixing combustion is selected than when stratified combustion is selected in the same operation state.

An exhaust gas recirculation valve for adjusting the amount of exhaust gas recirculated to the intake passage may be provided. At this time, when the control unit determines that the concentration of the evaporated fuel gas in the purge passage is higher than a predetermined value, the control unit performs uniform mixed combustion,
It is preferable that the exhaust gas recirculation valve be fully closed.

A sensor for detecting the concentration of hydrocarbons in the purge passage may be provided. At this time, it is preferable that the control unit determines that the concentration of the evaporated fuel gas in the purge passage is high when the concentration of the hydrocarbon detected by the sensor is higher than a predetermined value.

[0010] A sensor for detecting the pressure in the fuel tank may be provided. At this time, it is desirable that the control means determines that the concentration of the evaporated fuel gas in the purge passage is high when the pressure detected by the sensor is higher than a predetermined value.

Further, a sensor for detecting the fuel temperature may be provided. At this time, it is preferable that the control means determines that the concentration of the evaporated fuel gas in the purge passage is high when the fuel temperature detected by the sensor is higher than a predetermined value.

Further, a sensor provided in the exhaust passage for detecting the air-fuel ratio may be provided. At this time, it is preferable that the control means determines the concentration of the evaporated fuel gas in the purge passage based on a deviation between the exhaust air-fuel ratio detected by the sensor and the target air-fuel ratio.

[0013]

FIG. 1 is an overall block diagram of a control system of a direct injection engine. The in-cylinder injection engine 1 directly injects fuel into a cylinder and burns an 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 are connected to an exhaust manifold 5.
Is in communication with An ignition plug 6 for igniting the air-fuel mixture is provided at the center of the combustion chamber in the cylinder head of the engine 1. An injector 7 for directly injecting fuel (gasoline) into the combustion chamber is provided near the intake valve 2 in the combustion chamber. In general, in-cylinder injection engine 1 needs to make fuel spray finer due to demands on combustion characteristics. Then, the fuel stored in the fuel tank 18 is raised to a specified pressure and supplied to the injector 7 through a fuel pipe (not shown).

The air cleaner 8 provided in the intake passage has:
It is connected to an air chamber 9 communicating with the intake manifold 3. Between the air cleaner 8 and the air chamber 9, an electric throttle valve 1 for adjusting the amount of intake air is provided.
0 is interposed. The throttle valve 10 is operated by the electric motor 11 and does not have a structure that is mechanically linked to the accelerator pedal 30. The opening of the throttle valve 10 (hereinafter referred to as "throttle opening")
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.

On the other hand, the exhaust manifold 5 communicates with the three-way catalytic converter 13 through an exhaust passage, and has a NOx storage catalytic converter 14 downstream thereof.
Is provided. Here, the NOx storage catalytic converter 14 has a catalyst in which a NOx storage material such as an alkali metal, an alkaline earth, or a rare earth, and a noble metal such as platinum are supported on a carrier such as alumina. Due to the storage function of NOx and O2, when the oxygen concentration of the exhaust gas is high, HC and CO are oxidized and reduced and NO
Absorb x. On the other hand, when the oxygen concentration in the exhaust gas decreases, the stored NOx is released, and the NOx is reduced and purified by the excess HC and CO without being oxidized and reduced. Exhaust gas purified via these converters 13 and 14 is discharged through a muffler 15.

An exhaust gas recirculation passage 16 is provided between the exhaust manifold 5 and the air chamber 9. The exhaust gas recirculation passage 16 has an exhaust gas recirculation valve 17 (hereinafter referred to as “E”) for adjusting the amount of exhaust gas recirculated to the intake passage.
GR valve). The EGR valve 17 is driven by a built-in stepper motor,
The opening is set by an output signal from the ECU 12. The opening degree of the EGR valve 17 (hereinafter referred to as “EGR opening degree”) is adjusted so that inert gas that does not contribute to combustion is appropriately mixed into the intake air flowing through the intake passage. Thereby,
The combustion temperature can be reduced, and the amount of NOx contained in the exhaust gas can be reduced.

The upper part of the fuel tank 18 is
It communicates with the air chamber 9 via a purge passage 19 for discharging the evaporated fuel gas (evaporation) generated in the inside. In the purge passage 19, a canister 20 and a purge control valve 21 are provided. Canister 20
Has an adsorbing portion made of activated carbon or the like for adsorbing the evaporator, and a fresh air inlet for introducing air is provided below the adsorbing portion. The purge control valve 21 employed in the present embodiment is a duty solenoid valve controlled by the ECU 12, but may be an appropriate one such as a linear solenoid valve or a step motor type.

The ECU 12 receives sensor signals from various sensors including the sensors 22 to 29. The fuel tank internal pressure sensor 22 is provided at an upper part in the fuel tank 18 and detects the pressure Pf in the tank 18.
The fuel temperature sensor 23 is provided in the fuel tank 18 and detects the temperature Tf of the fuel. Note that the fuel temperature sensor 23 may be provided in a fuel pipe (not shown) for supplying fuel to the injector 7. The HC sensor 24 is provided in the purge passage 19 and detects the concentration of hydrocarbon (HC) in the purge passage 19. Thereby, the purge passage 1
The evaporation concentration De in 9 is specified. Note that 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 for detecting the throttle opening θt and the accelerator opening θa (corresponding to the depression amount of the accelerator pedal 30), respectively. Engine speed sensor 2
Reference numeral 6 denotes a sensor for calculating the engine speed Ne. For example, a crank angle sensor that generates an output pulse every time the crankshaft rotates a predetermined angle can be used. The engine water temperature sensor 27 is a sensor that detects a water temperature Te of the engine cooling water, and faces the cooling water passage of the engine 1.

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. 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 has the same value as the target air-fuel ratio when there is no evaporative purge and EGR (ignoring blow-by gas). However, the actual air-fuel ratio does not match the target air-fuel ratio due to disturbance factors such as an evaporation purge, an inflow of exhaust gas, and aging. Therefore, the difference between the actual air-fuel ratio and the target air-fuel ratio is corrected by performing the air-fuel ratio feedback control.

The ECU 12 calculates a fuel injection amount, an ignition timing, and the like according to a control program stored in a ROM based on a current operation state detected from various sensors, and calculates a fuel injection amount and an ignition plug 6 for the injector 7 and the ignition plug 6. Outputs control signal. In addition, the ECU 12 outputs an instruction value to the electric motor 11 in order to secure a necessary intake air amount by adjusting the throttle opening, and an EGR valve 17 in order to secure an appropriate exhaust gas recirculation amount. Outputs the indicated value to. Further, the ECU 12 controls the opening of the purge control valve 21 by outputting an instruction value DUTY defining the duty ratio to the purge control valve 21.

FIG. 2 is a flowchart showing a combustion mode determination routine. The ECU 12 repeatedly executes a series of procedures shown in this flowchart at predetermined intervals (for example, 10 ms). In principle, the combustion mode is determined by referring to the combustion mode determination map shown in FIG. 4 from the current operation state. First, in step 1, the sensor information in the current cycle, that is, the engine speed Ne, the accelerator opening θa, the engine water temperature Te, and the evaporation concentration De are read.

Next, it is determined whether or not the engine coolant temperature Te is higher than a determination threshold Teth (step 2).
If a negative determination is made in step 2, that is, if the engine is in a cold state or in a warming-up state,
The combustion mode instruction flag FMODE is set to "3" without referring to the determination map of FIG. 4 (step 8). The instruction content of the combustion mode instruction flag FMODE is as follows. FMODE instruction Description “1” Stratified combustion instruction “2” First uniform mixed combustion instruction (with uniform mixed combustion + EGR) “3” Second uniform mixed combustion instruction (uniform mixed combustion + no EGR)

Here, the stratified combustion is a combustion method in which fuel injection by the injector 7 is started in the compression stroke and ended immediately before ignition, and the rear end of the fuel spray is ignited by the ignition plug 6 to burn the air-fuel mixture. is there. In the stratified combustion, only the air around the fuel is used, and stable combustion can be obtained with an extremely small amount of fuel relative to the amount of charged air (A / F = about 25 to 40). Sometimes suitable. On the other hand, in the homogeneous mixed combustion, the fuel is used earlier (for example, at the end of the exhaust stroke or the intake stroke) than in the stratified combustion.
This is a combustion method in which the fuel is injected into the cylinder, the injected fuel is sufficiently diffused in the cylinder, and the injected fuel and the air are uniformly mixed and ignited. The uniform mixed combustion has a high air utilization rate and can improve the output of the engine (A / F = about 12 to 23), and is therefore suitable for high load and high speed operation.

When the instruction flag FMODE is set to "3" in step 8, the routine proceeds to return, and the execution of this routine in the current cycle is ended. While the instruction flag FMODE is set to “3”, the uniform mixed combustion is continued with the EGR valve 17 fully closed (no EGR) by a combustion execution routine provided separately from this routine. Thus, warming up of the engine is promoted while the engine is warming up.

On the other hand, if the determination in step 2 is affirmative, it is determined whether or not the reference result of the determination map in FIG. 4 is in the stratified combustion region (step 3). That is, it is determined in which combustion region shown in FIG. 4 the operating state specified by the engine speed Ne and the accelerator opening θa corresponding to the required output of the engine is included. As can be seen from FIG. 4, the low-load low-rotation state is included in the stratified combustion region, and the other operation states are included in the uniform mixed combustion region.

If a negative determination is made in step 3 (if not in the stratified combustion region), it is determined whether or not the reference result of the determination map in FIG. 4 is in the first homogeneously mixed combustion region (step 6). . When the determination is affirmative in step 6 (when it corresponds to the first uniform mixed combustion region)
The instruction flag FMODE is set to "2" (step 7), and if a negative determination is made (corresponding to the second homogeneously mixed combustion region), it is set to "3" (step 8). Thereby, the contents of the instruction flag FMODE (“2”,
According to “3”), the first or second uniform mixed combustion is performed. That is, when the first uniform mixed combustion is instructed, the throttle opening and the EGR opening are set according to the operating state with reference to the opening map and the like. On the other hand, the second
Is instructed, the throttle opening is set according to the operating state, as described above.
The opening is set to 0, that is, fully closed.

On the other hand, if the determination in step 3 is affirmative, that is, if the reference result of the determination map in FIG.
It is determined whether it is higher than eth (step 4). If a negative determination is made in step 4, that is,
If the evaporation concentration De is low, the combustion mode instruction flag FMOD
E is set to "1" (step 5). Therefore, stratified combustion is executed according to the reference result of the determination map. On the other hand, if the vapor concentration De is high, the process proceeds from step 4 to step 8, where the combustion mode instruction flag FMODE is set to "3". Thereby, the sensor information Ne,
Even in the case where the operation state specified from θa corresponds to the stratified combustion region, the second uniform mixed combustion is forcibly executed.

FIG. 3 is a flowchart showing an evaporative purge control routine. This routine is also repeatedly executed at a predetermined interval (for example, 10 ms). First, in step 11, the sensor information in this cycle, that is, the engine speed Ne and the throttle opening θt are read.

Next, it is determined whether or not the combustion mode instruction flag FMODE is "1", that is, whether or not stratified combustion is instructed (step 12). If stratified combustion is instructed, the process proceeds to step 13, where a low flow rate duty ratio min is set as an instruction value DUTY (duty ratio) for setting the opening of the purge control valve 21. Basically, the opening of the purge control valve 21 is set such that the ratio between the intake air amount Q and the purge flow rate P (purge rate P / Q) is constant except in an operation state in which the throttle opening is considerably large. You. In step 13, the purge rate is 0%,
That is, the value of the low flow duty ratio min may be set to 0 (fully closed) (purging prohibited), or a setting may be made to perform a low flow purge (for example, a purge rate of about 1%). When purging at a low flow rate, the low flow rate duty ratio min can be calculated, for example, from the low flow rate purge opening degree map shown in FIG. That is, with reference to the opening degree map, the low flow duty ratio min (7% to 100%) with interpolation calculation based on the throttle opening degree θt and the engine speed Ne.
%) Is calculated. The opening degree map shown in FIG.
Like the opening degree maps shown in FIGS. 6 and 7 described below,
It is stored in the ROM of the ECU 12. Step 13
Is calculated by the purge control valve 2
1 (step 17).

On the other hand, if a negative determination is made in step 12 (during uniform mixed combustion), the combustion mode instruction flag FMODE
Is "2" or "3" (step 14). The combustion mode instruction flag FMODE is "2"
, That is, when the first uniform mixed combustion is instructed, the medium flow purge is executed. In this case, the medium flow duty ratio mid which becomes the instruction value DUTY is calculated from the medium flow purge opening degree map shown in FIG. That is, referring to the opening degree map, the medium flow duty ratio mid (15% to 100%) is calculated with interpolation calculation based on the throttle opening degree θt and the engine speed Ne. The instruction value DUTY calculated in step 15 is output to the purge control valve 21 (step 17). As can be seen by comparing the opening degree maps shown in FIGS. 5 and 6,
In the same operation state (same throttle opening θt), the duty ratio is set to be larger during the middle flow purge than during the low flow purge (as a result, the purge flow becomes larger).

On the other hand, if a negative determination is made in step 14, that is, if the second uniform mixed combustion is instructed by the instruction flag FMODE, a large flow purge is performed. In this case, the large flow duty ratio max that becomes the instruction value DUTY is calculated from the large flow purge opening degree map shown in FIG. That is, with reference to the opening degree map, the duty ratio mid (20% to 100%) with interpolation calculation based on the throttle opening degree θt and the engine speed Ne.
Is calculated. Indication value calculated in step 16
DUTY is output to the purge control valve 21 (step 17). As can be seen by comparing the opening degree maps shown in FIGS. 5 to 7, in the same operating state (the same throttle opening degree θt), the duty ratio set at the time of the large flow rate purge is larger than that at the time of the other purges. (The result is the highest purge flow rate).

As described above, in this embodiment, even in an operation state in which stratified charge combustion is to be performed, when the purge concentration is high, uniform mixed combustion is forcibly executed. By shifting to the homogeneous mixture combustion, a sufficient intake negative pressure for purging the evaporator is secured, and a large pressure difference is generated between the intake negative pressure and the internal pressure of the purge passage 19. As a result, the evaporation adsorbed by the canister 20 can be effectively sucked into the combustion chamber of the engine 1.

Further, during the stratified combustion, the evaporator discharged without significantly contributing to the combustion can be completely burned by forcibly shifting to the homogeneous mixed combustion when the evaporative concentration is high. Therefore, the fuel injection amount can be reduced by the amount of the purged evaporation. As a result, since the evaporation can be used efficiently, the fuel efficiency of the in-cylinder injection engine can be further improved.

In the above-described embodiment, when the evaporative concentration De is higher than the predetermined value in the stratified combustion region (step 4), the homogeneous mixed combustion without the EGR (the EGR valve 17 is fully closed) (the instruction flag FMODE is set to "3"). )) (Step 8). The reason for this is that E
If the GR valve 17 is set to the fully closed state, the intake negative pressure (the negative pressure in the air chamber 9) is increased by the amount of the exhaust gas recirculation, that is, the intake negative pressure is increased. This is because purging can be performed. On the contrary,
If an affirmative determination is made in step 4, uniform mixed combustion with EGR (instruction flag FMODE is “2”) may be instructed. In this case, since the opening control of the EGR valve 17 is performed, the intake negative pressure becomes shallower by the opening degree (the efficiency of the evaporative purge also relatively decreases). However, it is necessary to secure the necessary intake negative pressure by uniform mixed combustion. Is possible.

In the above-described embodiment, the HC sensor 2
4 is used to directly detect the evaporation concentration. However, the present invention is not limited to this, and the evaporative concentration may be estimated using, for example, the following method.

1. Estimation Based on Fuel Tank Internal Pressure Since the evaporative concentration tends to increase as the pressure in the fuel tank 18 increases, the evaporative concentration can be estimated from the pressure in the fuel tank 18. In particular,
When the pressure Pf detected by the fuel tank internal pressure sensor 22 is higher than a predetermined value, it is determined that the evaporation concentration is high.

2. Estimation based on fuel temperature Since the evaporative concentration tends to increase as the fuel temperature increases, it is possible to estimate the evaporative concentration from the fuel temperature. Specifically, when the fuel temperature Tf detected by the fuel temperature sensor 23 is higher than a predetermined value, it is determined that the evaporation concentration is high.

3. Estimation Based on Exhaust Air-Fuel Ratio The deviation between the exhaust air-fuel ratio and the target air-fuel ratio tends to increase as the concentration of the evaporated evaporator increases. Therefore,
It is also possible to estimate the evaporative concentration based on the deviation of the air-fuel ratio. To explain this point more specifically, 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.

## EQU1 ## Tp = K × Q / Ne Ti = Tp × Φ × LAMBDA + Ts

That is, the basic fuel injection pulse width Tp is
It is calculated based on the engine speed Ne and the intake air amount Q. Note that K is an injector characteristic correction constant. The fuel injection pulse width Ti is calculated based on the equivalent ratio Φ, which is a control variable of the air-fuel ratio, the basic fuel injection pulse width Tp, and the like. Here, LAMBDA is an air-fuel ratio feedback correction coefficient, and by appropriately setting this correction coefficient,
Control is performed so that the exhaust air-fuel ratio converges to the target air-fuel ratio.
Ts is an invalid injection pulse width determined by the battery voltage. The details of the mathematical formula are described in
Since it is described in JP-A-11-36968, please refer to it if necessary.

In order to maintain a certain air-fuel ratio, it is necessary to correct the fuel injection amount of the injector 7 by decreasing as the vapor concentration to be purged becomes higher. Therefore, the air-fuel ratio feedback correction coefficient LAMBD is set to be smaller than the originally set value. It gets smaller. Therefore, assuming that there is no significant change in disturbance factors such as the EGR amount and that the purge control valve 21 is open, the value of the feedback correction coefficient LAMBDA has a correlation with the evaporation concentration. In view of such a correlation, it is possible to estimate the purge concentration to some extent from the feedback correction coefficient LAMBDA set according to the deviation between the exhaust air-fuel ratio and the target air-fuel ratio.

[0041]

As described above, according to the present invention, even in an operation state in which stratified charge combustion is to be performed, uniform mixed combustion is executed in a situation where the evaporation concentration is high. As a result, it is possible to secure a negative intake air pressure deep enough to effectively purge the evaporation. At the same time, in the uniform mixed combustion, the purged evaporator can be completely burned, so that the fuel injection amount can be reduced by the amount of the purged evaporator. As a result, since the evaporation can be used efficiently, the fuel efficiency of the in-cylinder injection engine can be further improved.

[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 showing a combustion mode determination routine.

FIG. 3 is a flowchart showing an evaporative purge control routine.

FIG. 4 is a combustion type determination map.

FIG. 5 is an opening map of a purge control valve in a low flow rate purge.

FIG. 6 is an opening map of a purge control valve in a medium flow rate purge.

FIG. 7 is an opening map of a purge control valve in a large flow purge.

[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, 1
2 control unit (ECU), 13 three-way catalytic converter,
14 NOx storage catalytic converter, 15 muffler, 16 exhaust gas recirculation passage, 17
Exhaust gas recirculation (EGR) valve, 18 fuel tank, 19
Purge passage, 20 canisters, 2
DESCRIPTION OF SYMBOLS 1 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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 25/07 570 F02M 25/07 570A F-term (Reference) 3G062 AA07 BA02 BA04 EA11 GA15 GA17 GA21 3G084 BA09 BA13 BA20 BA27 DA02 FA00 FA13 FA26 FA29 FA37

Claims (7)

[Claims] 1. A control device for a direct injection engine, wherein said control device is provided in a purge passage connecting an intake passage and a fuel tank, and varies an amount of fuel vapor gas flowing into said intake passage in accordance with an opening degree. A valve, and a control unit that selects one of the combustion modes of stratified combustion or uniform mixed combustion according to an operation state, and adjusts an opening degree of the control valve according to the selected combustion mode; When the control means determines that the concentration of the evaporated fuel gas in the purge passage is higher than a predetermined value, the control means selects the uniform mixed combustion even if the operation state in which the stratified combustion should be performed. Control device for in-cylinder injection engine. 2. The control means sets the opening of the control valve larger when uniform mixing combustion is selected than when stratified combustion is selected in the same operation state. A control device for a direct injection engine according to claim 1. 3. An exhaust gas recirculation valve for adjusting an amount of exhaust gas recirculated to the intake passage, wherein the control means determines that the concentration of the evaporated fuel gas in the purge passage is higher than a predetermined value. The control apparatus for a direct injection engine according to claim 1 or 2, wherein uniform mixing combustion is performed, and the exhaust gas recirculation valve is fully closed. 4. The apparatus according to claim 1, further comprising: a sensor for detecting a concentration of hydrocarbons in said purge passage, wherein said control means is configured to control said purge passage when a concentration of hydrocarbons detected by said sensor is higher than a predetermined value. 3. The control device for a direct injection engine according to claim 1, wherein it is determined that the concentration of the evaporated fuel gas in the inside is high. 5. The fuel cell system according to claim 1, further comprising: a sensor for detecting a pressure in the fuel tank, wherein the control unit detects the pressure of the fuel gas in the purge passage when the pressure detected by the sensor is higher than a predetermined value. 3. The control device for a direct injection engine according to claim 1, wherein the control unit determines that the concentration is high. 6. A sensor for detecting a fuel temperature, wherein the control means increases the concentration of the evaporated fuel gas in the purge passage when the fuel temperature detected by the sensor is higher than a predetermined value. 3. The control device for a direct injection engine according to claim 1, wherein the control unit determines that the control is performed. 7. A sensor provided in an exhaust passage for detecting an exhaust air-fuel ratio, wherein the control means controls the purge based on a deviation between the exhaust air-fuel ratio detected by the sensor and a target air-fuel ratio. 3. The control device for a direct injection engine according to claim 1, wherein a concentration of the evaporated fuel gas in the passage is determined.