JP4010092B2 - In-cylinder internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct injection internal combustion engine that can promote exhaust gas purification.
[0002]
[Prior art]
In recent years, a spark ignition type cylinder injection internal combustion engine (hereinafter also referred to as a direct injection gasoline engine) has been put into practical use as an automobile engine. In the intake pipe injection gasoline engine, the fuel supply timing into the cylinder is limited only when the intake valve is opened, but in the direct injection gasoline engine, the fuel supply into the cylinder can be performed at any timing. For this reason, fuel injection can be performed at an optimal timing for uniform combustion by premixing to obtain a larger output, or ultra lean stratified combustion can be performed at the time of partial load, and fuel consumption can be reduced.
[0003]
[Problems to be solved by the invention]
However, the direct injection gasoline engine has a problem that it is easy to discharge visible smoke and high-concentration HC.
By examining these generation mechanisms, we found the following.
Smoke is prominently generated when the air-fuel ratio is made rich under the condition that the wall surface temperature of the combustion chamber is low, such as during racing immediately after cold start.
[0004]
HC has a high concentration when operating with a rich air-fuel ratio in order to suppress knocking and excessive temperature rise of the exhaust gas purification catalyst when operating under high speed and high load conditions such as high speed fully open travel. become.
The fuel includes various components from a component having a relatively low boiling point that is easy to vaporize and mix to a component having a relatively high boiling point that is difficult to vaporize and mix, but in the case of an intake pipe injection gasoline engine, as shown in FIG. Low-boiling components in the fuel injected from the injection valve 102 into the intake pipe 101 [see FIG. 7A] are selectively supplied directly into the cylinder 103, and the remaining vaporization / mixing is difficult (evaporation is difficult). ) Component stays in the intake pipe 101 [see FIG. 7B], is vaporized over a sufficient vaporization time, and is supplied to the cylinder 103 in the next stroke.
[0005]
On the other hand, in the case of a direct-injection gasoline engine, as shown in FIG. 8, all the boiling point components of the fuel are supplied directly from the injection valve 102 to the cylinder 103 [see FIG. 8 (a)]. High boiling components in the fuel that are difficult to evaporate easily during combustion in the cold state where the wall surface temperature is low or at high speed operation where sufficient mixing time cannot be ensured are easily burnt in the liquid phase [see FIG. 8B], This is considered to be a factor that emits smoke and HC.
[0006]
By the way, Japanese Patent Laid-Open No. 9-280092 discloses a technique for correcting the advance angle of the fuel injection end timing when the fuel injection end timing is later than the intake valve closing timing in order to suppress the generation of HC and smoke. ing.
However, in the case of a direct injection gasoline engine, HC and smoke are generated because all the boiling point components of the fuel are supplied directly into the cylinder as described above, and the high boiling point components in the fuel that are difficult to evaporate are liquid. Combustion in the same phase is also a major factor, and it is not possible to sufficiently suppress the generation of HC and smoke by simply correcting the fuel injection timing without considering such points.
[0007]
The present invention has been devised in view of such problems, and provides a direct injection internal combustion engine that can suppress smoke and HC emissions in the direct injection internal combustion engine. Objective.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned target, the direct injection internal combustion engine of the present invention directly injects fuel into the cylinder during the intake stroke of the engine by the intake stroke fuel injection means. When the intake stroke fuel injection means is operated , In a specific operating state that is at least one of a cold operation of the engine, a high output operation in which the air-fuel ratio of the engine is rich or stoichiometric, and a low fuel consumption operation in which the air-fuel ratio is lean , the control means The operation of the intake valve closing timing varying means is controlled so that the valve closing timing is retarded and the air-fuel mixture blown back to the intake port increases.
[0009]
The fuel in the air-fuel mixture blown back to the intake port evaporates sufficiently in the intake port, mixes with the intake air in the next stroke, and is supplied into the cylinder. Therefore, if the air-fuel mixture blown back to the intake port is increased, the amount of fuel that does not evaporate in the cylinder and remains in the liquid phase and combusts can be reduced, and smoke and HC emissions can be suppressed.
[0011]
Furthermore, the control means, during the acceleration increase of the fuel injection quantity, and / or when full acceleration of the engine is preferably configured so as to prohibit control to retard the closing timing of the intake valve (claim 2 ).
The intake valve closing timing variable means is configured to be capable of adjusting a delay level of the intake valve closing timing, and the control means is configured to reduce the delay in response to an output request to the engine. It is preferable to control the variable means (Claim 3 ).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings .
Also not a, cylinder injection type internal combustion engine of spark ignition type according to the present embodiment (hereinafter, also referred to as direct injection gasoline engines or simply the engine) configuration will be described. It is assumed that this engine is mounted on an automobile.
[0013]
As shown in FIG. 1, the cylinder head 2 of the engine 1 is provided with an ignition plug 4 for each cylinder 3 and a fuel injection valve 6 as fuel injection means that opens directly into the combustion chamber 5. The fuel injection valve 6 is driven by the ignition coil 4A and the driver 6A by the driver 6A. A piston 8 connected to the crankshaft 7 is provided in the cylinder 3, and a cavity 9 recessed in a hemispherical shape is formed on the top surface of the piston 8. The fuel injection valve 6 can directly inject fuel into the cylinder during the intake stroke of the engine, and also functions as an intake stroke fuel injection means.
[0014]
An intake port 11 that can communicate with the combustion chamber 5 via the intake valve 10 and an exhaust port 13 that can communicate with the combustion chamber 5 via the exhaust valve 12 are formed in the cylinder head 2. The intake port 11 is disposed substantially vertically above the combustion chamber 5 and forms a reverse tumble flow by intake air in the combustion chamber 5 in cooperation with the cavity 9 on the top surface of the piston 8.
A water temperature sensor 16 for detecting the cooling water temperature is provided on the water jacket 15 on the outer periphery of the cylinder 3, and a crank angle sensor 17 for outputting a signal at a predetermined crank angle position is provided on the crankshaft 7 with the intake valve 10 and the exhaust valve. A cylinder identification sensor (cam angle sensor) 20 that outputs a cylinder identification signal corresponding to the camshaft position is attached to each of the camshafts 18 and 19 that drive the cylinder 12. Since the engine speed can be calculated based on the crank angle signal, the crank angle sensor 17 also functions as an engine speed detecting means.
[0015]
A variable valve mechanism 41 is provided between the camshaft 18 and the intake valve 10. The variable valve mechanism 41 functions as intake valve closing timing variable means that can change the closing timing of the intake valve 10. That is, the variable valve mechanism 41 can retard the closing timing of the intake valve 10 by a predetermined amount from the normal timing.
[0016]
The variable valve mechanism 41 of this embodiment is of a cam phase angle change type (cam swing type), and the opening period (corresponding to the crank angle) of the intake valve 10 is constant, but the opening / closing timing can be shifted. The opening / closing timing of the intake valve 10 can be retarded with respect to the normal time.
A description of the variable valve mechanism 41 is omitted since various known ones can be applied. Here, what is required of the variable valve mechanism 41 is a function for making the closing timing of the intake valve 10 variable. Therefore, for example, depending on the type of the variable valve mechanism 41, such as one configured to drive the intake valve 10 by selectively using a plurality of cams having different cam profiles (cam switching type), the intake valve 10 You may use what changed only a closing time, without changing an opening time.
[0017]
The intake system is configured from the upstream side in the order of an air cleaner 21, an intake pipe 22, a throttle body 23, a surge tank 24, and an intake manifold 25, and an intake port 11 is provided at the downstream end of the intake manifold 25. The throttle body 23 is provided with an electronically controlled throttle valve (ETV) 30 as an air amount adjusting means for adjusting the amount of air flowing into the combustion chamber 5, and the opening degree control of the ETV 30 is performed according to the accelerator opening degree. In addition to the above control, idle speed control and control of introducing a large amount of intake air during lean operation, which will be described later, can be performed.
[0018]
Further, an air flow sensor 37 for detecting the intake air flow rate is provided immediately downstream of the air cleaner 21, and a throttle position sensor 38 for detecting the throttle opening of the ETV 30 and a fully closed state of the ETV 30 are detected on the throttle body 23 to generate an idle signal. An idle switch 39 for outputting is provided.
The exhaust system includes an exhaust manifold 26 having an exhaust port 13 and an exhaust pipe 27 in this order from the upstream side. A three-way catalyst 29 for exhaust gas purification is interposed in the exhaust pipe 27, and an O ₂ is connected to the exhaust manifold 26. A sensor 40 is provided.
[0019]
Although the fuel supply system is not shown, the fuel whose pressure is adjusted to a predetermined high pressure (several tens of atmospheres (for example, about 2 to 7 MPa)) is guided to the fuel injection valve 6, and the high pressure fuel is supplied from the fuel injection valve 6. Is to be injected.
Further, an accelerator position sensor (hereinafter referred to as APS) 42 for detecting an accelerator pedal depression amount (accelerator position) θap is provided.
[0020]
In order to control the operation of each engine control element such as the spark plug 4, the fuel injection valve 6, and the ETV 30, an electronic control unit (ECU) 60 having a function as control means for the internal combustion engine is provided. The ECU 60 includes an input / output device, a storage device for storing a control program, a control map, etc., a central processing unit, a timer, a counter, and the like. Based on the position information and the like, the ECU 60 controls the engine control elements described above.
[0021]
In particular, this engine is an in-cylinder injection engine. Fuel injection can be performed at any timing, and uniform mixing is performed by fuel injection centered on the intake stroke to perform uniform combustion, and fuel injection centered on the compression stroke. Stratified combustion can be performed using the above-described reverse tumble flow. As an operation mode of this engine, a stoichiometric operation mode in which the air-fuel ratio is maintained in the vicinity of the theoretical air-fuel ratio by feedback control based on detection information of the O ₂ sensor 40, and an enrichment operation mode in which the air-fuel ratio is richer than the theoretical air-fuel ratio. And a lean operation mode in which lean combustion is performed with the air-fuel ratio leaner than the stoichiometric air-fuel ratio.
[0022]
The ECU 60 selects one of the operation modes according to an engine rotation speed (hereinafter referred to as engine rotation speed) Ne and a target value (target Pe) of the average effective pressure Pe indicating the engine load state based on a map (not shown). When the engine speed Ne is small and the target Pe is small, the lean operation mode is selected. As the engine speed Ne and the target Pe increase, the operation mode is selected in the order of stoichiometric and enrichment. Go.
[0023]
The engine speed Ne is calculated from the output signal of the crank angle sensor 17, and the target Pe is calculated from the engine speed Ne and the throttle opening detected by the throttle position sensor 38.
In addition, the ECU 60 controls the variable valve mechanism 41 so that the closing timing of the intake valve 10 is retarded with respect to the normal time when the engine is cold and during high-speed steady operation, and the intake stroke (in this case, particularly the first half of the intake stroke). ), The fuel is injected during the period, and the air-fuel mixture blown back to the intake port 11 is increased.
[0024]
That is, smoke is likely to occur when the operation is performed with the air-fuel ratio rich under conditions where the wall surface temperature of the combustion chamber is low, such as during racing immediately after cold start. In addition, when operating under high-speed and high-load conditions such as high-speed full-open running, HC is operating with a rich air-fuel ratio to suppress knocking and excessive temperature rise of the exhaust gas purification catalyst. High concentration. In the case of a direct injection gasoline engine, such smoke generation and HC increase are caused by burning all the boiling point components of the fuel directly into the cylinder and burning the high boiling point components in the fuel that are difficult to evaporate in the liquid phase. It is to reach.
[0025]
On the other hand, the fuel in the air-fuel mixture blown back to the intake port 11 evaporates over a sufficient amount of time in the intake port 11, mixes with the intake air in the next stroke, and is supplied into the cylinder. If the air-fuel mixture blown back to the intake port 11 is increased, the amount of fuel that does not evaporate in the cylinder and remains in the liquid phase and combusts can be reduced, and smoke and HC emissions can be suppressed. In this case, it is assumed that the blow-back flow to the intake port 11 is an air-fuel mixture containing fuel, and it is necessary to retard the closing timing of the intake valve 10 after injecting fuel during the intake stroke. .
[0026]
However, in the present embodiment, the condition for retarding the closing timing of the intake valve 10 is when the engine is cold or during high-speed steady operation (except for high-speed full-open travel). The reason why the smoke and HC generation conditions are not used as they are is that the closing timing of the intake valve 10 is retarded (conditions for increasing the blowback mixture) when the control is simplified and the blowback mixture is increased. This is in consideration of the point that the output is reduced.
[0027]
That is, if the closing timing of the intake valve 10 is retarded to increase the blowback mixture, the charging efficiency and the actual compression ratio are reduced, leading to a reduction in engine output. For this reason, when the engine output request is high, it is desirable to give priority to securing the engine output without delaying the closing timing of the intake valve 10. Therefore, during operation under high-speed and high-load conditions in which the HC emission concentration increases, it is limited to high-speed operation (ie, high-speed steady operation) excluding acceleration with high engine output requirements and high-speed full-open travel. The delay of the closing timing of the intake valve 10 is executed.
[0028]
In addition, as specific conditions at the time of high-speed steady operation, here, the engine speed Ne or the vehicle speed V calculated from the output signal of the crank angle sensor 17 is equal to or higher than a predetermined speed Ne ₀ or V ₀ set in advance. and, we have a the accelerator opening speed dθap / dt calculated from the detected accelerator position θap is below a predetermined opening speed [Delta] [theta] ₀ which is set in advance in APS42. Since the predetermined rotational speed Ne ₀ is a reference value for high speed determination, a correspondingly high value is set, and since the predetermined opening speed Δθ ₀ is a reference value for steady running determination, a correspondingly small value is set.
[0029]
In addition, when the engine is cold, the operation of making the air-fuel ratio rich, such as racing, causes significant smoke.However, when the engine is cold, the fuel vaporization deteriorates, so even in the operation where the air-fuel ratio is not rich, Although it is not, smoke is likely to occur. Furthermore, since there is less demand for engine output during racing or when the air-fuel ratio is not rich during cooling, there is no problem because the air-fuel mixture is increased by retarding the closing timing of the intake valve 10 and causing no adverse effects. Smoke generation can be suppressed. Therefore, when the engine is cold, the closing timing of the intake valve 10 is retarded not only when the air-fuel ratio is rich.
[0030]
Further, as a specific condition when the engine is cold, here, the cooling water temperature Tw detected by the water temperature sensor 16 is set to be equal to or lower than a predetermined water temperature Tw ₀ set in advance. The water temperature Tw ₀ is set to a correspondingly low value because it is a reference value for engine cold state determination.
Since the direct injection internal combustion engine as one embodiment of the present invention is configured as described above, the intake valve closing timing and the fuel injection timing are determined according to the state of the engine 1 as shown in FIG. Be controlled.
[0031]
That is, it is determined whether or not the engine 1 is in a cold state (step S10). Here, if the cooling water temperature Tw is equal to or lower than the predetermined water temperature Tw _0, it is assumed that the engine 1 is in a cold state, and the process proceeds to step S30. The valve mechanism 41 is controlled and fuel injection is performed during a period centered on the first half of the intake stroke.
[0032]
On the other hand, if the cooling water temperature Tw is higher than the predetermined water temperature Tw _0, it is determined that the engine 1 is not in the cold state, and the process proceeds to step S20 to determine whether or not the engine 1 is in high-speed steady operation. Here, if the engine rotational speed Ne is equal to or higher than the predetermined rotational speed Ne ₀ and the accelerator opening speed dθap / dt is equal to or lower than the predetermined opening speed Δθ ₀ , the routine proceeds to step S30, and the intake valve 10 is passed through the ECU 60. The variable valve mechanism 41 is controlled so that the closing timing of the engine is retarded from the normal timing, and fuel injection is performed during a period centered on the first half of the intake stroke.
[0033]
If the engine speed Ne is less than the predetermined engine speed Ne ₀ or the accelerator opening speed dθap / dt is larger than the predetermined opening speed Δθ _{0 in} step S20, the engine is not in high-speed steady operation (that is, even if the engine 1 is cold). However, in step S40, the variable valve mechanism 41 is controlled through the ECU 60 so that the closing timing of the intake valve 10 is normal, and fuel injection is performed at a timing according to the set combustion mode. To do. That is, if uniform combustion is selected, fuel injection is performed centering on the intake stroke, and if stratified combustion is selected, fuel injection is performed centering on the compression stroke.
[0034]
In this way, when the engine 1 is in a cold state or at a high speed steady operation, as shown in FIG. 3A, fuel injection is performed during a period centered on the first half of the intake stroke, and the closing timing of the intake valve 10 is retarded. As shown in FIG. 3B, the intake valve 10 is opened until the initial stage of the compression stroke after the intake bottom dead center (or the first half of the compression stroke), and the air-fuel mixture in the cylinder is introduced into the intake pipe (intake pipe) in the first half of the compression stroke. A so-called blow-back that flows backward in the (port) 11 occurs.
[0035]
FIG. 4 shows the flow velocity in the intake port in correspondence with the crank angle (compression top dead center is set to 0 ° as a reference). The case where the opening / closing timing of the intake valve is normally set is indicated by a broken line, and the opening / closing timing of the intake valve is shown. The solid line shows the case where the angle is retarded. As shown by the solid line, if the closing timing of the intake valve is retarded, the flow velocity in the intake port becomes negative during the compression stroke (particularly between 540 and 630 °), that is, the air-fuel mixture becomes the intake port. It turns out that it flows backward in 11.
[0036]
FIG. 5 shows the HC concentration in the intake port corresponding to the crank angle (compression top dead center is set to 0 ° as a reference), and the case where the opening / closing timing of the intake valve is normally set is indicated by a broken line (supplied as standard). The case where the opening / closing timing of the intake valve is delayed is indicated by a solid line (denoted as a delay). As shown by the solid line, it can be seen that when the closing timing of the intake valve is retarded, the HC concentration significantly increases around the compression stroke. This significant increase in the HC concentration means a significant increase in the air-fuel mixture blowback.
[0037]
The air-fuel mixture that has flowed back into the intake port 11 in this way can evaporate with sufficient time while remaining in the intake port 11, and is mixed with the intake air in the next stroke and supplied into the cylinder. Is done. That is, as shown in FIG. 3 (c), the combustion in the combustion stroke is performed by subtracting the current blow-out amount from the fuel injected in the cylinder in the immediately preceding intake stroke, and the previous stroke (previous combustion cycle). The fuel in the blown-back air-fuel mixture blown back into the intake port 11 is added. While the fuel in the blown-back mixture stays in the intake port 11, even the high boiling point components that are difficult to evaporate are sufficiently evaporated and used for combustion. As a result, the mixing of the fuel and the air proceeds, and the amount of fuel that reaches combustion in the liquid phase can be reduced, so that the generation of smoke and HC due to combustion can be suppressed.
[0038]
FIG. 6 shows the results of tests conducted under the same conditions of engine speed, volumetric efficiency, and air-fuel ratio. The amount of blown air, amount of blown fuel, amount of HC generated after combustion, with respect to the closing timing of the intake valve 10, The amount of smoke generated after combustion is shown. As shown in FIG. 6, when the closing timing of the intake valve 10 is retarded (changed to the compression top dead center side), both the amount of blown air and the amount of blown fuel increase, and the amount of HC generated, It can be seen that the amount of smoke generated decreases.
[0039]
This is because if the closing timing of the intake valve 10 is delayed, the backflow of the air-fuel mixture from the cylinder to the intake port 11 increases, the amount of blown air and the amount of blown fuel both increase, and the blown fuel is taken into the intake air. Even the high boiling point components that are difficult to evaporate while staying in the port 11 are sufficiently evaporated and supplied to the subsequent combustion to reduce the HC generation amount and the smoke generation amount. It is considered that the generation of HC and smoke can be suppressed as the delay is delayed.
[0040]
However, even if the closing timing of the intake valve 10 is greatly delayed, the effect of reducing HC and smoke reaches its peak. In this test result, HC and smoke are sufficiently reduced if the closing timing of the intake valve 10 is delayed so that the amount of blown fuel reaches about 10% of the fuel injection amount. It is desirable to delay the closing timing of the intake valve 10 so as to reach about 10% or more. In addition, in this test result, even if the closing timing of the intake valve 10 is further delayed so that the amount of fuel blown back is larger than about 10% of the fuel injection amount, the effect of reducing HC and smoke becomes dull. Considering this point, it is desirable to delay the closing timing of the intake valve 10 so that the amount of blown fuel reaches about 10% of the fuel injection amount.
[0041]
Thus, according to the direct injection gasoline engine (in-cylinder injection internal combustion engine), the direct injection gasoline engine (cylinder injection internal combustion engine) is combined with a variable valve mechanism that can function as intake valve closing timing variable means. By simply delaying the closing timing of the intake valve 10 as the intake stroke injection, it is possible to reduce the discharge of HC and smoke. For example, as in the case of a system that assists injection of fuel into the intake pipe, the fuel for assist injection Without adding piping or fuel injection valves, it is possible to promote the reduction of HC and smoke emissions at a low cost with a simple hardware configuration.
[0042]
In particular, the variable valve mechanism is generally equipped to switch the drive timings of the intake valve and the exhaust valve to those suitable for the low and high engine speed ranges. Therefore, if a variable valve mechanism that changes the intake timing and exhaust timing according to the operating state of the engine is provided, this can be used to delay the intake valve closing timing, adding a hardware configuration Therefore, it is possible to promote the reduction of HC and smoke emission at low cost.
[0043]
In addition, if the intake valve closing timing is delayed, the volumetric efficiency is reduced and the output torque is reduced. In this embodiment, the intake valve closing is performed even during high-speed and high-load operation of the engine in which the HC concentration increases. The timing is delayed only during high-speed steady operation, and in situations such as acceleration where the output demand is strong, the intake valve closing timing is not delayed in favor of the output over the HC concentration reduction. Ensuring output and reducing HC concentration can be achieved in a well-balanced manner.
[0044]
The in-cylinder injection internal combustion engine of the present invention is not limited to the above embodiment, and can be implemented with various modifications without departing from the spirit of the present invention.
For example, in the above embodiment, when the engine is cold, the intake valve closing timing is not limited to when the engine is heavily loaded, such as during racing, that is, both when the engine is heavily loaded and when the load is low (including lean operation). However, the intake valve closing timing may be delayed only when the engine has a high load where the occurrence of smoke becomes significant.
[0045]
In the above-described embodiment, in order to achieve a good balance between securing the output of the engine and reducing the HC concentration during high-speed operation of the engine, even during high-speed and high-load operation of the engine where the HC concentration increases. The intake valve closing timing is delayed only during high-speed steady operation with low engine output requirements. For example, when the delay level of the intake valve closing timing can be adjusted, the delay is reduced according to the output request. In this way, the intake valve closing timing may be delayed in a wider high speed and high load operation region. In particular, during high-speed operation, there is no allowance for fuel vaporization time, so it is effective to reduce the HC concentration by delaying the intake valve closing timing as wide as possible.
[0046]
It is also conceivable that the engine cold is defined within a predetermined time after the cold start or within a predetermined time after the start, or the vehicle speed is used for high speed determination of the engine.
In the above embodiment, the fuel injection is performed in the intake stroke as a premise for delaying the intake valve closing timing. Conversely, the predetermined condition is limited to the operation mode in which the fuel injection is performed in the intake stroke. The intake valve closing timing may be delayed under control.
[0047]
【The invention's effect】
As described above, according to the in-cylinder injection internal combustion engine of the present invention according to claim 1, by increasing the blown back air-fuel mixture to the intake port, the liquid phase is combusted without being evaporated in the cylinder. It is possible to reduce the amount of fuel that reaches, and to suppress smoke and HC emissions. In particular, if there is a device that can change the closing timing of the intake valve in the existing period, the above effect can be achieved without adding a large cost by simply adding or changing the control content without adding a device specially. Can be obtained .
According to a cylinder injection type internal combustion engine of the present invention according to 請 Motomeko 2 can be achieved with good balance and a reduction in the security and HC concentration of the output of the engine.
According to the cylinder injection type internal combustion engine of the present invention according to claim 3 , the intake valve closing timing can be delayed in a wider high speed and high load operation region.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an overall configuration of a direct injection internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a flowchart showing intake valve control in the direct injection internal combustion engine according to the embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view for explaining the operation of the direct injection internal combustion engine according to the embodiment of the present invention in the order of (a) to (c).
FIG. 4 is a diagram for explaining the effect of intake valve control in the direct injection internal combustion engine according to the embodiment of the present invention.
FIG. 5 is a diagram for explaining the effect of intake valve control in the direct injection internal combustion engine according to the embodiment of the present invention.
FIG. 6 is a diagram for explaining the effect of intake valve control in the direct injection internal combustion engine according to the embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view for explaining fuel behavior by conventional intake pipe injection in the order of (a) and (b).
FIG. 8 is a schematic cross-sectional view for explaining fuel behavior by conventional in-cylinder injection in the order of (a) and (b).
[Explanation of symbols]
1 In-cylinder internal combustion engine (direct injection gasoline engine)
4 Spark plug 6 Fuel injection valve 41 as intake stroke fuel injection means Variable valve mechanism 60 as intake valve closing timing variable means ECU

Claims (3)

An intake stroke fuel injection means for directly injecting fuel into the cylinder during the intake stroke of the engine;
An intake valve closing timing variable means capable of changing the closing timing of the intake valve for opening and closing the intake port;
At least one of a cold operation of the engine, a high output operation in which the air-fuel ratio of the engine is rich or stoichiometric, and a low fuel consumption operation in which the air-fuel ratio is lean is performed during the operation of the intake stroke fuel injection means. And a control means for controlling the operation of the intake valve closing timing varying means so as to retard the closing timing of the intake valve and increase the blowback mixture to the intake port in a specific operating state. A cylinder injection type internal combustion engine characterized by the above . The control means does not perform control for retarding the closing timing of the intake valve even during the specific operation state during acceleration increase of the fuel injection amount and / or when the engine is fully opened. The in-cylinder injection internal combustion engine according to claim 1 . The intake valve closing timing varying means is configured to be able to adjust a delay level of the intake valve closing timing, and the control means is configured to reduce the delay in response to an output request to the engine. The in-cylinder injection internal combustion engine according to claim 1, wherein the internal combustion engine is controlled.

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