JP4120452B2 - In-cylinder internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-cylinder injection internal combustion engine that directly injects fuel into a cylinder, and more particularly to a technique for increasing the homogeneity of an air-fuel mixture during homogeneous combustion.
[0002]
[Prior art]
An in-cylinder spark ignition internal combustion engine that injects fuel directly into the cylinder of the internal combustion engine injects fuel directly into the cylinder. There is a risk that the homogeneity of the air-fuel mixture is deteriorated because the time required for conversion is short. In this case, the combustion state is deteriorated, and problems such as a decrease in output performance of the internal combustion engine, deterioration in emissions, and increase in smoke generation are caused.
[0003]
In addition, since the fuel is injected into the cylinder at a high pressure, the fuel directly collides with and adheres to the opposing wall surface of the cylinder and the top surface of the piston before the fuel is vaporized and atomized, particularly during cold weather. There is a risk (see FIG. 5). Even in such a case, the homogeneity of the air-fuel mixture deteriorates, causing problems such as a decrease in output performance, deterioration in emissions, and an increase in smoke generation.
[0004]
On the other hand, there is an apparatus that accelerates fuel vaporization and atomization by opening the exhaust valve during the intake stroke to flow the already burned gas into the cylinder and raising the temperature in the cylinder (for example, see Patent Document 1). ).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 06-280581 [Patent Document 2]
Japanese Patent Laid-Open No. 2000-199440
[Problems to be solved by the invention]
However, in the technique described in Patent Document 1, since the exhaust valve is opened during the entire stroke or almost the entire stroke of the intake stroke, the fuel injected into the cylinder flows out from the exhaust port before combustion and is charged. Efficiency may deteriorate.
[0007]
Further, according to the study by the present inventors, even if the exhaust valve is opened before fuel injection or after fuel injection even during the intake stroke, the effect of promoting fuel vaporization and atomization is small. It has been found.
[0008]
The present invention has been made in view of the above-described problems, and an object of the present invention is to promote the vaporization and atomization of the fuel injected into the cylinder without deteriorating the charging efficiency. An object of the present invention is to provide a direct injection internal combustion engine.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the direct injection internal combustion engine according to the present invention has a fuel injection means for directly injecting fuel into the cylinder, and opens mainly during the exhaust stroke, and is already burned from within the cylinder. A cylinder for exhausting the gas, and an exhaust valve driving means for opening and closing the exhaust valve, the exhaust valve driving means opening the exhaust valve even during the intake stroke, and allowing the burned gas to flow into the cylinder In the internal injection internal combustion engine, the exhaust valve driving means opens the exhaust valve during the intake stroke and the fuel injection means injects fuel.
[0010]
In an internal combustion engine that injects fuel directly into the cylinder, compared with the case of injecting fuel into the intake port, the period from injection of fuel to ignition is shorter, so the injected fuel is sufficiently vaporized.・ May not atomize. In such a case, the fuel and air are not mixed well, the fuel is unevenly distributed with respect to the air, and the combustion of the air-fuel mixture becomes unstable. As a result, the output performance of the internal combustion engine is deteriorated, emission is deteriorated, smoke is generated, and the like.
[0011]
Such a phenomenon is likely to occur when the temperature in the cylinder is low, such as when cold. This is because if the temperature in the cylinder is low, the injected fuel is difficult to vaporize and atomize. Further, the injected fuel collides with the opposing wall surface of the cylinder or the top surface of the piston and adheres to these surfaces, so that the fuel and air cannot be mixed well. Further, such a phenomenon is likely to occur even when the rotational speed of the output shaft of the internal combustion engine is high. This is because the higher the number of revolutions of the output shaft, the shorter the time from fuel injection to ignition, so that the injected fuel is less likely to vaporize and atomize.
[0012]
Therefore, the exhaust valve driving means opens mainly during the exhaust stroke and opens the exhaust valve that discharges the burnt gas from the cylinder during the intake stroke. Then, in the intake stroke, the pressure in the cylinder becomes negative, so that the high-temperature burned gas flows again into the cylinder. As a result, the temperature in the cylinder rises and the fuel injected into the cylinder is easily vaporized and atomized.
[0013]
The direct injection internal combustion engine according to the present invention is characterized in that the exhaust valve driving means opens the exhaust valve during the intake stroke and the fuel injection means injects fuel. According to the present invention, when the exhaust valve is opened and high-temperature burned gas flows in during the period when the fuel is being injected, the inside of the cylinder is warmed and the high-temperature burned gas flowing in again is Since it can be made to collide with the fuel in flight after injection, vaporization and atomization of fuel can be promoted.
[0014]
On the other hand, even during the intake stroke, the collision between the fuel and the burned gas does not occur even if the burned gas is introduced before or after the fuel is injected. The effect of promoting vaporization and atomization is small. Also, if the exhaust valve is opened for a long time, even during the intake stroke, the injected fuel may be discharged from the cylinder to the exhaust port before burning. In such a case, the filling efficiency is deteriorated.
[0015]
Therefore, in the present invention, during the period when the fuel injection means injects the fuel, the exhaust valve is opened to effectively promote the vaporization and atomization of the injected fuel without deteriorating the charging efficiency. did.
[0016]
In addition, it is preferable that the fuel injected from the fuel injection unit and the burned gas flowing into the cylinder due to the exhaust valve driving unit opening the exhaust valve during the intake stroke collide at substantially right angles. is there. In such a case, vaporization and atomization of the fuel during the flight after injection can be effectively promoted, and the flow velocity of the fuel during the flight can be reduced, and the cylinder wall or piston top surface can be reduced. It is possible to improve the homogeneity of the air-fuel mixture by reducing the fuel that collides and adheres.
[0017]
Preferably, the exhaust valve driving means starts opening the exhaust valve at an injection start timing of the fuel injection means and ends it at an injection end timing. In this way, since the high-temperature burned gas can collide with all the injected fuel, the vaporization and atomization of the fuel can be promoted more reliably.
[0018]
The exhaust valve driving means can adjust the opening amount of the exhaust valve, and it is preferable that the opening amount is increased as the temperature in the cylinder is lower. As described above, the lower the temperature in the cylinder, the more difficult it is for the injected fuel to vaporize and atomize. Therefore, it is preferable to adjust the opening amount of the exhaust valve that is opened during the intake stroke according to the temperature in the cylinder, and the opening amount is increased as the temperature in the cylinder is lower.
[0019]
In this way, the lower the temperature in the cylinder, the higher the temperature of the burned gas that flows into the cylinder, so the temperature in the cylinder can be increased earlier and the fuel in flight The already burned gas collides, fuel vaporization / atomization can be promoted, and the collision / attachment of the fuel to the cylinder wall surface can be prevented.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0021]
Hereinafter, an in-cylinder injection spark ignition internal combustion engine according to an embodiment of the present invention will be described.
[0022]
The internal combustion engine 1 includes a cylinder block 2 and a cylinder head 3, and a cylinder (cylinder) 4 is formed therein. A piston 5 is accommodated in the cylinder 4 so as to be capable of reciprocating, and a combustion chamber 6 is formed in a space surrounded by the top surface 5 a of the piston 5, the inner wall of the cylinder 4, and the cylinder head 3. .
[0023]
The cylinder head 3 is provided with a spark plug 7. The spark plug 7 is energized at an appropriate timing via the igniter 8 and ignites the fuel / air mixture filled in the combustion chamber 6. Similarly, the cylinder head 3 is provided with a fuel injection valve 9 that directly faces the injection hole in the combustion chamber 6. The fuel injection valve 9 is an electromagnetically driven on / off valve that supplies pressurized fuel pressurized by a high-pressure pump (not shown) or the like into the combustion chamber 6 at an appropriate amount and at an appropriate timing.
[0024]
Further, an intake port 10 communicating with the combustion chamber 6 and an exhaust port 11 communicating with the combustion chamber 6 are formed in the cylinder head 3, and the boundary between the intake port 10 and the combustion chamber 6 is opened and closed. And an exhaust valve 13 that opens and closes the boundary between the exhaust port 11 and the combustion chamber 6 is provided.
[0025]
The intake valve 12 includes a valve body 12b at the tip of a shaft member 12a and is driven to open and close by an intake valve drive mechanism 14. The intake valve drive mechanism 14 basically repeats reciprocating motion (open / close valve operation) in synchronization with rotation of a crankshaft (not shown) that is an output shaft of the internal combustion engine. The timing and the valve lift amount (valve opening amount) can be changed as appropriate.
[0026]
Similarly to the intake valve 12, the exhaust valve 13 is also provided with a valve body 13b at the tip of the shaft member 13a, and is driven to open and close by the exhaust valve drive mechanism 15. The exhaust valve drive mechanism 15 basically repeats reciprocating motion (open / close valve operation) in synchronization with the rotation of the crankshaft, but the open / close timing of the exhaust valve 13 and the valve lift amount (valve open amount) are also different. It can be changed as appropriate.
[0027]
As the intake valve drive mechanism 14 and the exhaust valve drive mechanism 15, mechanisms using various operating principles can be adopted. For example, a cam mechanism that interlocks with the rotation of the crankshaft, which can selectively drive the intake valve 12 or the exhaust valve 13 using a plurality of cams, or a cam that interlocks with the rotation of the crankshaft. A mechanism or the like that can be used together with a mechanism for correcting the operation of the cam to drive the valve can be exemplified.
[0028]
Further, a mechanism capable of applying an electromagnetic force to the intake valve 12 or the exhaust valve 13 along the reciprocal movement direction can be employed. When such a mechanism is employed, there is no need to link the operation of the intake valve 12 or the exhaust valve 13 with the rotation of the crankshaft, so that the degree of freedom in controlling the operation range and operation speed is increased.
[0029]
By utilizing such functions of the intake valve drive mechanism 14 and the exhaust valve drive mechanism 15, the ECU 16 of the internal combustion engine 1, which will be described later, can open and close the intake valve 12 and the exhaust valve 13 and the valve lift amount (valve open amount). Can be variably controlled.
[0030]
In the internal combustion engine 1, air is sucked into the cylinder 4 from the intake port 10 by opening the intake valve 12 during the intake stroke. Thereafter, when combustion of an air-fuel mixture composed of air sucked into the cylinder 4 and fuel injected from the fuel injection valve 9 is performed, the piston 5 reciprocates by the combustion energy at that time. Then, the reciprocating motion of the piston 5 is converted into a rotational motion of a crankshaft (not shown) that is an output shaft of the internal combustion engine 1 by a connecting rod (not shown) connected to the piston 5. On the other hand, the burned air-fuel mixture (pre-combusted gas) existing in the cylinder 4 is discharged from the cylinder 4 to the exhaust port 11 by opening the exhaust valve 13 in the exhaust stroke.
[0031]
The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU) 16 for controlling the internal combustion engine 1. The ECU 16 is an arithmetic logic circuit including a CPU, ROM, RAM, backup RAM, and the like.
[0032]
Various sensors such as a water temperature sensor 17 and a crank position sensor (not shown) attached to the internal combustion engine 1 are connected to the ECU 16 via electric wiring so that output signals of the various sensors described above are input to the ECU 16. It has become.
[0033]
On the other hand, the fuel injection valve 9, the intake valve drive mechanism 14, the exhaust valve drive mechanism 15 and the like are connected to the ECU 16 via electric wiring, and the ECU 16 is connected to the fuel injection valve 3, the intake valve drive mechanism 14, and the exhaust valve drive mechanism 15. Etc. can be controlled.
[0034]
For example, the ECU 16 executes input of output signals of various sensors, calculation of engine speed, calculation of fuel injection amount, calculation of fuel injection timing, and the like in a basic routine to be executed at regular intervals. Various signals input by the ECU 16 and various control values obtained by the ECU 16 in the basic routine are temporarily stored in the RAM of the ECU 16.
[0035]
Further, the ECU 16 reads various control values from the RAM in the interrupt processing triggered by the input of signals from various sensors and switches, the passage of a fixed time, or the input of a pulse signal from the crank position sensor, and controls them. The fuel injection valve 9 is controlled according to the value.
[0036]
Specifically, when the fuel injection amount control process is started, first, the operation state of the internal combustion engine 1, in this case, the rotational speed of the internal combustion engine, the accelerator (not shown) opening degree, and the like are provided in the RAM of the ECU 16. Read into the area. Then, based on the map, the fuel injection amount is calculated from the rotational speed of the internal combustion engine, the accelerator opening, and the like.
[0037]
The valve opening time of the fuel injection valve 9 is determined based on the fuel injection amount and the fuel pressure. Thereafter, the fuel injection valve 9 provided in the cylinder corresponding to the fuel injection timing is controlled to open for the valve opening time, and fuel corresponding to the calculated fuel injection amount is injected into the corresponding cylinder. .
[0038]
The ECU 16 switches the combustion mode of the air-fuel mixture in the combustion chamber 6 between stratified combustion and homogeneous combustion in accordance with the operating state of the internal combustion engine that changes depending on the engine speed, load, and the like. During the execution of stratified combustion, a combustible air-fuel mixture is made to exist around the spark plug 7 mainly by fuel injection in the compression stroke, and the air-fuel mixture is combusted by ignition by the spark plug 7 in that state. Further, during the execution of the homogeneous combustion, a homogeneous mixture in which fuel is evenly mixed with air is formed by fuel injection in the intake stroke, and the homogeneous mixture is burned by ignition by the spark plug 7 in that state. Done.
[0039]
By the way, fuel injection is performed in the intake stroke, such as in an idling operation state in homogeneous combustion, and both the fuel injection amount and the intake air amount are reduced, and the gas flow (airflow) in the cylinder 4 is also weakened. In the operating state, the fuel injected into the cylinder 4 is difficult to vaporize and atomize, so that the fuel and air cannot be mixed well. As a result, the fuel is unevenly distributed in the combustion chamber 6 and is unevenly distributed, the combustion of the air-fuel mixture becomes unstable, misfires and torque fluctuations occur, and the rotational fluctuations of the internal combustion engine 1 may increase.
[0040]
In addition, when the rotational speed of the internal combustion engine 1 is high, such as in a high-load operation state in homogeneous combustion, the time from when the fuel is injected to when it is ignited is short, so the injected fuel is sufficiently vaporized and atomized. Otherwise, the fuel and air may not be well mixed and there is a risk of ignition. As a result, combustion worsens, resulting in a decrease in output performance, emission deterioration, smoke generation, and the like.
[0041]
What has been described above is likely to occur when the temperature in the cylinder 4 is low, such as during cold weather. This is because if the temperature in the cylinder 4 is low, the injected fuel is difficult to vaporize and atomize. Further, when the fuel is cold, the injected fuel collides with the opposing wall surface of the cylinder 4 or the top surface 5a of the piston and adheres to the surface (see FIG. 5), so that the fuel and air are well mixed. This is because it will not be performed.
[0042]
Therefore, in the present embodiment, in the combustion mode in which homogeneous combustion is performed such that fuel is injected in the intake stroke, the exhaust valve 13 is opened in accordance with the fuel injection timing from the fuel injection valve 9 and the exhaust port 11 is opened. Let the hot burned gas flow in. Specifically, for example, it is executed as described below.
[0043]
FIG. 2 is a diagram showing a change in the lift amount of the valve with respect to the crankshaft angle, and mainly shows the lift amount of the valve during the exhaust stroke and the intake stroke. As shown in the figure, the intake valve 19 is driven and controlled to open (lift) mainly in the intake stroke (curve N1). On the other hand, the exhaust valve 13 is driven and controlled to open (lift) mainly in the exhaust stroke (curve E1).
[0044]
Further, when the exhaust valve 13 according to the present embodiment is a homogeneous combustion region in which fuel is injected during the intake stroke, the exhaust valve 13 is driven and controlled to open (lift) during the intake stroke (curve E2). In other words, the valve is opened once in the exhaust stroke in one cycle consisting of the intake stroke, the compression stroke, the explosion stroke, and the exhaust stroke of the internal combustion engine 1, and then is closed and then opened again during the intake stroke. Controlled.
[0045]
The start timing of the valve opening performed during the intake stroke is the same as the start timing of the fuel injection by the fuel injection valve 9, and the end timing of the valve opening is the end of the fuel injection by the fuel injection valve 9. Same as the time. That is, the exhaust valve 13 is driven and controlled to open during the fuel injection period of the fuel injection valve 9.
[0046]
Specifically, as shown in FIG. 2, the exhaust valve 13 starts the first opening slightly before the bottom dead center (BDC) at which the exhaust stroke starts, and exhausts the burned gas from the cylinder. After that, when the top dead center of the exhaust stroke ends a little, the first valve opening is ended.
[0047]
Thereafter, drive control is performed so that the second valve opening is performed during the fuel injection period of the fuel injection valve 9 during the intake stroke. Then, as the piston 5 descends, the pressure in the cylinder 4 becomes negative, and the burned gas discharged during the exhaust stroke as described above flows into the cylinder again (→ in FIG. 1). As a result, the inside of the cylinder 4 is warmed and, as shown in FIG. 1, the high-temperature burned gas flowing in again collides with the fuel in flight after being injected, so that the fuel is vaporized and atomized. Is promoted.
[0048]
In addition, as shown in FIG. 1, when the fuel injection angle and the inflow angle of the already burned gas are substantially perpendicular to each other, the flow rate of the injected fuel is already flowing from the exhaust port. Since it is decelerated by the combustion gas, it is difficult to collide and adhere to the cylinder wall surface or the piston top surface. Further, even if the fuel adheres to the cylinder wall surface or the piston top surface, the evaporation is promoted by the high-temperature burned gas flow flowing from the exhaust port.
[0049]
As a result, since the fuel and air are well mixed and combustion is performed satisfactorily, rotational fluctuations can be stabilized, and output performance degradation, emission deterioration, smoke generation, and the like can be suppressed.
[0050]
In addition, the exhaust valve 13 is not opened during the entire period during which the intake valve 12 is open, but the exhaust valve 13 is opened only during the same period as the fuel injection period by the fuel injection valve 9 during the intake stroke, and the injected fuel. Since the minimum burned gas necessary for vaporizing and atomizing the gas is introduced, it is possible to suppress deterioration of the charging efficiency.
[0051]
As described above, the fuel injection period varies according to the amount of fuel injected into the cylinder 4, but the valve opening period of the exhaust valve 13, which is opened in accordance with the fuel injection period during the intake stroke, Similarly, it fluctuates according to the fluctuation of the fuel injection period.
[0052]
Incidentally, as described above, the lower the temperature in the cylinder 4, the harder the injected fuel is vaporized and atomized. Therefore, it is preferable to change the opening amount of the exhaust valve 13 to be opened according to the fuel injection period during the intake stroke according to the temperature in the cylinder 4. In other words, the lower the temperature in the cylinder 4, the more the opening amount of the exhaust valve 13 is increased, the hot burned gas is frequently flowed into the cylinder 4 to increase the temperature in the cylinder 4 early, and the flight It is preferable that a large number of already burned gases collide with the fuel in the fuel so as to promote fuel vaporization / atomization and prevent collision / adhesion of the fuel to the cylinder wall surface or the like.
[0053]
Specifically, the lift amount of the exhaust valve 13 that is driven and controlled when the temperature in the cylinder 4 is low is a curve E3 indicated by a broken line in FIG. 2, and the fuel injection period is the same. The valve opening start timing and the valve opening end timing are not changed, but are adjusted to the fuel injection timing, and the lift amount for each crank angle is simply changed.
[0054]
The opening amount of the exhaust valve 13 is an area surrounded by the curve E2 or E3 in FIG. 2 and the horizontal axis where the valve lift amount is zero. That is, when the valve opening period is the same, the amount of opening increases as the lift amount of the exhaust valve increases. However, since the fuel injection period in the intake stroke varies, the ECU 16 determines the lift amount of the exhaust valve on the basis of the fuel injection period, that is, the valve opening period, once the opening amount is determined.
[0055]
FIG. 3 shows the relationship between the in-cylinder temperature and the opening amount of the exhaust valve 13 that is opened during the intake stroke. As shown in this figure, the opening amount of the exhaust valve 13 is decreased as the temperature in the cylinder increases, and the valve is not opened when the temperature exceeds a predetermined temperature Tf.
[0056]
The predetermined temperature Tf is high in the cylinder, the injected fuel is easily vaporized and atomized, the fuel and air are mixed well, the combustion is performed well, the output performance is deteriorated, the emission is deteriorated, the smoke is generated, etc. Is the minimum value of the temperature at which generation of water is prevented, for example, 90 ° C. The predetermined temperature Tf is a value determined in advance for each internal combustion engine.
[0057]
Next, a control routine for setting the opening amount of the exhaust valve 13 that is opened when fuel is injected during the intake stroke of the internal combustion engine will be described with reference to the flowchart of FIG.
[0058]
This control routine is a routine that is stored in advance in the ROM of the ECU 16, and is a routine that is executed by the ECU 16 as an interrupt process triggered by elapse of a predetermined time or input of a pulse signal from the crank position sensor.
[0059]
In this routine, the ECU 16 first determines in step 100 whether or not it is a homogeneous combustion region. If it is determined that the region is a homogeneous combustion region, the process proceeds to step 101. On the other hand, if it is determined that the region is not the homogeneous combustion region, the routine proceeds to step 104.
[0060]
In step 101, the ECU 16 determines whether or not the in-cylinder temperature is lower than the predetermined temperature Tf described above. In order to recognize the in-cylinder temperature, a temperature sensor may be provided in the cylinder and directly detected, or the in-cylinder temperature may be estimated based on the detection value of the water temperature sensor 17.
[0061]
If it is determined in step 101 that the cylinder internal temperature is lower than the predetermined temperature Tf, the process proceeds to step 102. If it is determined that the cylinder internal temperature is equal to or higher than Tf, the process proceeds to step 104.
[0062]
In step 102, the opening amount of the exhaust valve 13 is determined. This is because a map showing the correlation between the in-cylinder temperature and the opening amount of the exhaust valve 13 as shown in FIG. 3 is stored in the ROM in advance, and the in-cylinder temperature recognized in step 101 is substituted into the map. To decide.
[0063]
Thereafter, the routine proceeds to step 103, where the opening amount determined in step 102 is set as the opening amount of the exhaust valve 13 during the intake stroke, and this routine is terminated.
[0064]
On the other hand, if it is determined in step 100 that the region is not a homogeneous combustion region, that is, if it is determined that the region is a stratified combustion region, or if it is determined in step 101 that the in-cylinder temperature is equal to or higher than Tf. In this case, the valve opening amount in the intake stroke is set to zero and the execution of this routine is terminated.
[0065]
Thus, when the opening amount of the exhaust valve 13 during the intake stroke is set periodically, in the homogeneous combustion region, the fuel injection valve for each cylinder is mainly separated from the valve opening during the exhaust stroke. The ECU 16 controls the exhaust valve drive mechanism 15 to drive the exhaust valve 13 so that the valve is opened by a set opening amount in accordance with the fuel injection period 9. Alternatively, in the stratified combustion region, since the exhaust valve 13 is set to zero so that the exhaust valve 13 does not open during the intake stroke, the ECU 16 controls the exhaust valve drive mechanism 15 to perform one cycle of four strokes. The exhaust valve 13 is driven so that the valve is opened only once during the exhaust stroke.
[0066]
As described above, in the present embodiment, the case where the present invention is applied to the internal combustion engine operated in both the homogeneous combustion and the stratified combustion mode has been described. However, the present invention is not limited to this, and the intake stroke is being performed. The present invention may be applied to an internal combustion engine that is operated only in homogeneous combustion where fuel is injected. As a control routine in this case, step 100 in the flowchart of FIG. 4 is omitted and used. Specifically, the process proceeds to step 101 immediately after starting, and whether or not the in-cylinder temperature is lower than Tf. Is determined. Since the subsequent processing is the same as described above, the description thereof is omitted.
[0067]
In the present embodiment, the case where the present invention is applied to a spark ignition internal combustion engine has been described. However, the present invention can also be applied to a compression ignition internal combustion engine. In general, in a compression ignition internal combustion engine, fuel is injected during a compression stroke. However, in an internal combustion engine in which sub-injection such as bi-rubber injection is performed, fuel may be injected during an intake stroke. In such a case, when the present invention is applied, vaporization / atomization of the fuel injected into the cylinder is promoted and combustion can be stabilized as described above, and the same effect as described above can be obtained. be able to.
[0068]
In addition, the present invention can be applied regardless of the number of exhaust valves per cylinder, but in an internal combustion engine having a plurality of exhaust valves per cylinder, it is opened during the period during which fuel is injected during the intake stroke. The number of exhaust valves to be valved may be at least one, and can be arbitrarily set for each internal combustion engine. Further, the number may be changed as appropriate according to the operating state of the internal combustion engine.
[0069]
【The invention's effect】
As described above, according to the direct injection internal combustion engine according to the present invention, the exhaust valve is opened during the period in which the fuel is injected in the intake stroke. It is possible to promote vaporization and atomization of the fuel injected into the cylinder without deteriorating the efficiency.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a direct injection spark ignition internal combustion engine according to an embodiment.
FIG. 2 is a graph showing changes in lift amounts of an intake valve and an exhaust valve with respect to a crank angle.
FIG. 3 is a diagram showing the relationship between the in-cylinder temperature and the opening amount of an exhaust valve that is opened during a period in which fuel is injected during an intake stroke.
FIG. 4 is a flowchart of a control routine that is executed to set an opening amount of an exhaust valve that is opened during a period in which fuel is injected during an intake stroke.
FIG. 5 is a schematic view of an internal combustion engine according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder block 3 Cylinder head 4 Cylinder 5 Piston 6 Combustion chamber 7 Spark plug 8 Igniter 9 Fuel injection valve 10 Intake port 11 Exhaust port 12 Intake valve 13 Exhaust valve 14 Intake valve drive mechanism 15 Exhaust valve drive mechanism 16 ECU
17 Water temperature sensor

Claims (2)

Fuel injection means for directly injecting fuel into the cylinder;
An exhaust valve that opens mainly during the exhaust stroke and exhausts the burned gas from within the cylinder;
Exhaust valve driving means for opening and closing the exhaust valve;
With
In the in-cylinder injection internal combustion engine in which the exhaust valve driving means opens the exhaust valve even during the intake stroke and flows the already burned gas into the cylinder.
The exhaust valve driving means opens the exhaust valve at an injection start timing of the fuel injection means so that the exhaust valve is opened during a period in which the fuel injection means injects fuel during an intake stroke. Start and end at the end of injection ,
The exhaust valve driving means, the open amount of the exhaust valve can be adjusted, cylinder injection type internal combustion engine characterized in that the temperature is much Hirakiryou enough if lower the exhaust valve in the cylinder. The fuel injected from the fuel injection means and the burned gas flowing into the cylinder collide substantially at right angles when the exhaust valve driving means opens the exhaust valve during the intake stroke. Item 2. The cylinder injection internal combustion engine according to Item 1 .

Images