JP2002089300A - In-cylinder direct injection internal combustion engine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To stabilize stratified combustion in combination with a variable valve mechanism. SOLUTION: An ignition plug is arranged substantially at the center of a combustion chamber recessed on a cylinder head side, and a shallow dish-shaped combustion chamber is recessed on a crown surface of a piston along a forward tumble flow. A fuel injection valve is arranged below the intake port so as to inject fuel in a direction obliquely downward with respect to the cylinder center line, and a part of the spray injected from the fuel injection valve is linearly transferred to the ignition plug. 1 is an in-cylinder direct injection internal combustion engine configured so as to face the shape. The intake valve includes a lift / operating angle variable mechanism that enlarges / reduces the lift / operating angle, and a variable phase mechanism that changes the phase of the operating angle. During stratified combustion, the intake valve opening timing is set to optimize the internal EGR, and the intake valve closing timing is set to optimize the spray penetration, that is, the in-cylinder pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder direct injection internal combustion engine capable of stratified charge combustion, and more particularly to a combination with a variable valve mechanism in order to stabilize stratified charge combustion by optimizing the valve lift characteristics of the engine. About technology.

[0002]

2. Description of the Related Art A variable valve timing mechanism is combined with an in-cylinder direct injection internal combustion engine that performs stratified combustion at low and medium loads,
A proposal for improving the state of stratified combustion by opening and closing the intake and exhaust valves is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-248277.

[0003] In this system, a variable valve timing mechanism capable of simultaneously delaying the opening timing and the closing timing is provided for both the intake valve and the exhaust valve, and the opening / closing timing of both the intake valve and the exhaust valve is determined during stratified combustion with a low load. When the intake valve is opened after the top dead center and the exhaust valve is closed later, the internal EGR
Increases, and the in-cylinder temperature increases. At the same time, it is disclosed that the intake valve closing timing is greatly retarded from the bottom dead center, so that the actual compression ratio is reduced and the pumping loss is reduced.

[0004]

However, the above-mentioned conventional structure mainly focuses on the control of the internal EGR, and the intake valve opening timing related to the internal EGR and the intake air related to the actual compression ratio. The valve closing timing cannot be controlled independently.

[0005] The present applicant has previously disclosed that a spark plug is disposed substantially at the center of a combustion chamber recessed on the cylinder head side, and a shallow dish-shaped combustion chamber is provided on a crown surface of a piston so as to follow a forward tumble flow. A fuel injection valve is disposed below the intake port so as to inject fuel in a direction obliquely downward with respect to the cylinder center line, and one of the sprays injected from the fuel injection valve is provided below the intake port. An in-cylinder direct-injection internal combustion engine whose section is directed straight to the ignition plug has been proposed (for example, Japanese Patent Application No. 11-242484). In this case, the reach of the spray toward the spark plug, that is, the penetration of the spray, greatly affects the stability of stratified combustion. The penetration depends on the in-cylinder pressure when the fuel is injected, that is, the actual compression ratio. However, in the above conventional device,
If the intake valve opening timing is determined to optimize the internal EGR, the intake valve closing timing related to the actual compression ratio is uniquely determined, so that the penetration of the spray cannot always be maintained optimally. There is a problem that the stratified combustion region in which stable operation is possible is relatively narrowly limited.

[0006]

According to a first aspect of the present invention, an ignition plug is provided at substantially the center of a combustion chamber recessed on a cylinder head side, and a piston is provided. A shallow dish-shaped combustion chamber is recessed along the forward tumble flow on the crown surface, and a fuel injection valve is provided below the intake port so as to inject fuel in a direction obliquely downward with respect to the cylinder center line. Is disposed, in a direct injection type internal combustion engine in which a part of the spray injected from the fuel injection valve is directed straight to the ignition plug,
A lift / operating angle variable mechanism that changes the operating angle and the lift amount while keeping the operating angle center of the intake valve substantially constant, and a phase variable mechanism that changes the phase of the operating angle center, comprising: It is characterized in that valve lift control is performed so as to optimize the penetration.

That is, by appropriately combining and controlling the variable lift / operating angle mechanism and the variable phase mechanism,
It is possible to separately optimize the opening timing and the closing timing of the intake valve. Therefore, the opening timing of the intake valve is determined by the internal EGR
However, the closing timing of the intake valve is not restricted by this, and the closing timing of the intake valve can be optimized in terms of the actual compression ratio that affects the penetration.

According to a second aspect of the present invention, the opening timing of the intake valve is advanced and the closing timing is retarded during the stratified charge combustion compared with the homogeneous combustion.
Further, it is characterized in that the closing timing of the exhaust valve is not changed.

According to a third aspect of the present invention, the opening timing of the intake valve is advanced during stratified charge combustion compared with homogeneous combustion.
The closing timing is a position advanced from the bottom dead center, and the closing timing of the exhaust valve is not changed.

The invention according to claim 4 is characterized in that the operating angle and the lift amount of the intake valve are controlled to be smaller in stratified charge combustion than in homogeneous charge combustion.

According to a fifth aspect of the present invention, the closing timing of the exhaust valve is not changed during stratified charge combustion than during homogeneous charge combustion.
The opening timing of the intake valve is advanced, and the closing timing of the intake valve after the bottom dead center is advanced with an increase in load.

According to a sixth aspect of the present invention, in the third aspect, the amount of advance from the bottom dead center of the closing timing of the intake valve during stratified charge combustion decreases as the load increases.

According to a seventh aspect of the present invention, in the third aspect, the operating angle and the lift amount of the intake valve during stratified combustion are:
It is characterized in that it increases with an increase in the engine speed.

According to an eighth aspect of the present invention, in the fifth aspect, the opening timing of the intake valve during stratified combustion is substantially constant regardless of the load.

A ninth aspect of the present invention is characterized in that the variable lift / operating angle mechanism has a characteristic that when the operating angle / lift amount is reduced, the maximum positive acceleration of the intake valve is reduced.

Further, the invention of claim 10 is characterized in that at the time of idling stratified combustion, the opening timing of the intake valve is retarded from the top dead center, and the closing timing is retarded than at the time of idling homogeneous combustion.

An eleventh aspect of the present invention is a variable lift / operating angle mechanism on the exhaust valve side for changing the operating angle and the lift amount while maintaining the operating angle center of the exhaust valve substantially constant, and changing the phase of the operating angle center. And a variable phase mechanism on the exhaust valve side.

According to a twelfth aspect of the present invention, the exhaust valve closing timing is advanced from the top dead center and the intake valve opening timing is delayed from the top dead center during stratified combustion. , Minus overlap.

Further, the invention of claim 13 is the invention of claim 12
Is characterized in that the period from the top dead center to the intake valve opening timing is longer than the period from the exhaust valve closing timing to the top dead center.

The lift / operating angle variable mechanism may include, for example, an eccentric cam rotatably driven by a drive shaft, a link arm fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, and A rotatable control shaft provided in parallel with the shaft and having an eccentric cam portion; a rocker arm rotatably mounted on the eccentric cam portion of the control shaft and swinging by the link arm; A swing cam that is rotatably supported by a shaft, is connected to the rocker arm via a link, and presses an intake valve by swinging with the rocker arm. By changing the rotational position of the cam portion, the operating angle and lift of the intake valve are simultaneously increased and decreased.

[0021]

According to the first aspect of the present invention, not only the internal EGR amount but also the actual compression ratio can be optimally controlled according to the load and the rotation speed of the internal combustion engine. Is optimized, and the area where stable stratified combustion can be performed is expanded.

According to the second aspect of the present invention, the internal EGR can be increased and the actual compression ratio can be reduced during stratified combustion without complicating the structure of the valve mechanism on the exhaust valve side.

According to the third aspect of the invention, the actual compression ratio can be reduced in the same manner as in the second aspect. In particular, since heat is received from the cylinder bore surface in the latter half of the intake stroke, atomization of the spray can be further achieved.

According to the fourth aspect of the invention, by reducing the lift during stratified charge combustion, the flow velocity of the intake air passing through the intake valve is improved, the gas flow is enhanced, and the combustion state is improved.

According to the fifth and sixth aspects of the present invention,
The actual compression ratio is increased with an increase in load, and an excessive increase in penetration is suppressed. Thus, the stratified region can be expanded in the load direction.

According to the seventh aspect of the invention, in the low rotation region where the gas flow rate is low, the flow rate of the intake air passing through the intake valve can be increased by setting the small lift. Then, as the amount of gas flow generated in the cylinder increases as the rotation speed increases, the lift amount is increased to reduce the throttle loss.

According to the invention of claim 8, the generation of smoke is suppressed, and the stratified region can be enlarged.

According to the ninth aspect of the present invention, the increasing time of the flow velocity at the time of the low lift is increased, and the area of the stratified combustion can be expanded.

According to the tenth aspect of the present invention, during idling stratified combustion, the valve overlap is reduced or negatively overlapped, and the combustion state of idling stratified combustion is improved by increasing the gas flow rate and increasing the in-cylinder temperature.
As a result, the fuel efficiency can be improved and the unburned fuel rate can be reduced.

According to the eleventh aspect, by combining the variable mechanism on the intake valve side and the variable mechanism on the exhaust valve side,
The valve overlap and the like can be set more freely.

According to the twelfth aspect of the present invention, the temperature of the internal EGR gas is further increased during the stratified charge combustion by advancing the exhaust valve closing timing to make the overlap negative.

According to the thirteenth aspect, in addition to the function and effect of the twelfth aspect, an effect of increasing the gas flow rate due to the in-cylinder negative pressure can be obtained, and the stratification region can be further expanded and the combustion efficiency can be improved. .

According to the fourteenth aspect of the present invention, when the magnitude of the operating angle is reduced, the lift amount is reduced at the same time, and the effect of reducing the lift and the function of reducing the operating angle are simultaneously realized. it can.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the structure of a variable valve mechanism for an intake valve used in a direct injection type internal combustion engine according to the present invention. A variable lift / operating angle mechanism 1 for changing the operating angle, and a variable phase mechanism 2 for advancing or retarding the phase at the center of the operating angle (phase with respect to a crankshaft not shown) are configured in combination. I have.

FIG. 2 shows only the lift / operating angle variable mechanism 1, and based on FIGS.
The variable operating angle mechanism 1 will be described. The variable lift / operating angle mechanism 1 has been proposed by the applicant of the present invention, but is known, for example, from Japanese Patent Application Laid-Open No. 11-107725, so that only its outline will be described.

The lift / operating angle variable mechanism 1 is rotatably supported by an intake valve 12 slidably provided on a cylinder head 11 via a valve guide (not shown) and a cam bracket 14 on the cylinder head 11. A hollow drive shaft 13, an eccentric cam 15 fixed to the drive shaft 13 by press-fitting or the like, and a drive bracket 1 rotatably supported by the same cam bracket 14 above the drive shaft 13.
3 and a rocker arm 1 swingably supported by an eccentric cam portion 17 of the control shaft 16.
8 and a tappet 19 arranged at the upper end of each intake valve 12
And a swing cam 20 that abuts against the swing cam 20. The eccentric cam 15 and the rocker arm 18 are linked by a link arm 25, and the rocker arm 18 and the swing cam 20 are linked by a link member 26.

The drive shaft 13 is driven by a crankshaft of the engine via a timing chain or a timing belt, as described later.

The eccentric cam 15 has a circular outer peripheral surface,
The center of the outer peripheral surface is offset from the axis of the drive shaft 13 by a predetermined amount, and the annular portion 25a of the link arm 25 is rotatably fitted to the outer peripheral surface.

The rocker arm 18 has a substantially central portion supported by the eccentric cam portion 17. One end of the rocker arm 18 is linked to an extension 25b of the link arm 25, and the other end is connected to the link. The upper ends of the members 26 are linked. The eccentric cam portion 17 is eccentric from the axis of the control shaft 16, so that the rocking center of the rocker arm 18 changes according to the angular position of the control shaft 16.

The swing cam 20 is rotatably supported by being fitted on the outer periphery of the drive shaft 13, and the lower end of the link member 26 is linked to the end 20a extending laterally. . On the lower surface of the swing cam 20, a base circular surface 24a concentric with the drive shaft 13 and a cam surface 24b extending in a predetermined curve from the base circular surface 24a to the end 20a.
The base circular surface 24a and the cam surface 24b are brought into contact with the upper surface of the tappet 19 according to the swing position of the swing cam 20.

That is, the base circle surface 24a is a base circle section in which the lift amount is 0. When the swing cam 20 swings and the cam surface 24b contacts the tappet 19, the base circle surface 24a gradually lifts. Will go. Note that a slight ramp section is provided between the base circle section and the lift section.

As shown in FIG. 1, the control shaft 16 is configured to rotate within a predetermined rotation angle range by a lift / operation angle control hydraulic actuator 31 provided at one end. The supply of the hydraulic pressure to the lift / actuation angle control hydraulic actuator 31 is controlled by the first hydraulic control valve 3 based on a control signal from the engine control unit 33.
2. Reference numeral 30 denotes a hydraulic pump serving as a hydraulic pressure source.

The operation of the lift / operating angle variable mechanism 1 will be described. When the drive shaft 13 rotates, the link arm 25 moves up and down by the cam action of the eccentric cam 15, and the rocker arm 18 swings accordingly. This rocker arm 1
The swing of 8 is transmitted to the swing cam 20 via the link member 26, and the swing cam 20 swings. This swing cam 20
, The tappet 19 is pressed and the intake valve 12 is lifted.

Here, when the angle of the control shaft 16 changes via the lift / operating angle control hydraulic actuator 31,
The initial position of the rocker arm 18 changes, and consequently, the initial swing position of the swing cam 20 changes.

For example, assuming that the eccentric cam portion 17 is located upward in the drawing, the rocker arm 18 is located upward as a whole, and the end portion 20a of the swing cam 20 is relatively pulled upward. . That is, the initial position of the swing cam 20 is inclined such that the cam surface 24b moves away from the tappet 19. Therefore, when the swing cam 20 swings with the rotation of the drive shaft 13, the base circle surface 24 a is long and the tappet 19 is long.
And the period during which the cam surface 24b contacts the tappet 19 is short. Accordingly, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.

Conversely, assuming that the eccentric cam portion 17 is located downward in the figure, the rocker arm 18 is located entirely downward, and the end portion 20a of the swing cam 20 is relatively pushed downward. Becomes That is, the initial position of the swing cam 20 is inclined in a direction in which the cam surface 24 b approaches the tappet 19. Therefore, with the rotation of the drive shaft 13, the swing cam 2
When 0 is swung, the portion in contact with the tappet 19 immediately shifts from the base circular surface 24a to the cam surface 24b. Therefore, the lift amount is increased as a whole, and the operating angle is also increased.

Since the position of the eccentric cam portion 17 can be continuously changed, the valve lift characteristic is accordingly changed.
As shown in FIG. 3, it changes continuously. That is, both the lift and the operating angle can be simultaneously enlarged and reduced simultaneously. In particular, in this case, the opening timing and the closing timing of the intake valve 12 change substantially symmetrically with the change in the lift / operating angle. When the lift becomes low, the maximum positive acceleration of the intake valve 12 also decreases.

Next, as shown in FIG. 1, the variable phase mechanism 2 includes a sprocket 35 provided at the front end of the drive shaft 13 and a sprocket 35 and the drive shaft 13.
And a phase control hydraulic actuator 36 that relatively rotates within a predetermined angle range. The sprocket 35 is linked to a crankshaft via a timing chain or a timing belt (not shown). The above phase control hydraulic actuator 36
The supply of hydraulic pressure to is controlled by a second hydraulic control valve 37 based on a control signal from the engine control unit 33. Reference numeral 30 denotes a hydraulic pump. By the hydraulic control of the phase control hydraulic actuator 36, the sprocket 35 and the drive shaft 13 rotate relatively, and the phase of the operating angle is advanced, as shown in FIG. That is, the lift characteristic curve itself does not change, and the whole is advanced or retarded. This change can also be obtained continuously. The phase variable mechanism 2 is not limited to a hydraulic type, and various configurations such as a type using an electromagnetic actuator are possible.

As the control of the variable lift / operating angle mechanism 1 and the variable phase mechanism 2, a sensor for detecting the actual lift / operating angle or phase may be provided to perform closed loop control, or Open loop control may be simply performed according to conditions.

FIG. 5 shows the overall configuration of an in-cylinder direct injection internal combustion engine having the above-described variable valve mechanism on the intake valve 12 side. In this internal combustion engine, a pent roof-shaped combustion chamber 51 is recessed on the cylinder head side, and an ignition plug 52 is disposed substantially at the center of the combustion chamber 51. The intake port 53 is configured to generate a forward tumble flow in the cylinder, and a shallow dish-shaped combustion chamber 55 is formed in the crown of the piston 54 so as to follow the forward tumble flow. . The shallow dish-shaped combustion chamber 55 has a substantially cylindrical surface whose cross-sectional shape in a plane passing through the center axis of the piston from the intake side to the exhaust side (a plane parallel to the plane of the drawing) approximates an arc having a predetermined radius of curvature. I have. A fuel injection valve 56 is disposed below the intake port 53 (more specifically, between the pair of intake ports 53) so as to inject fuel in a direction obliquely downward with respect to the cylinder center line. The hollow cone-shaped spray F injected from the fuel injection valve 56
Is configured so as to go straight to the ignition plug 52. The intake port 53 may be provided with an intake control valve 59 for controlling gas flow. In this embodiment, the exhaust valve 58 that opens and closes the exhaust port 57 does not have a variable valve mechanism and is opened and closed with a fixed lift characteristic.

Next, control of the variable valve mechanism will be described with reference to a flowchart shown in FIG.

First, in step 101, engine operating conditions such as engine speed, load, oil temperature, water temperature and the like are fetched, and in step 102, it is determined whether or not the engine is in a region where stratified combustion operation is to be performed. If it is determined that the stratified combustion region has occurred, in a succeeding step 103, the required intake valve opening timing (required IVO) is referred to from the map value according to the rotational speed and the load.
Since the required intake valve opening timing corresponds to the required recirculation rate (EGR rate) in the internal EGR, the map may be referred to according to the engine operating conditions as described above, or the cylinder volume, The required value may be calculated based on the operating air-fuel ratio of the cycle and the required oxygen concentration.

In step 104, the required intake valve closing timing (required IVC) is similarly read with reference to a map.
Then, in step 105, the request IVO and the request I
The required operating angle and phase are determined from VC and
At 6, these values are set.

The above-mentioned demand IVC is determined, for example, from a map whose characteristics are schematically shown in FIG. That is,
In the stratified combustion state where the rotation speed and the load are low, the gas flow is small, and the degree of stratification depends on the spray form of the fuel injection valve 56 and the spray reaching distance (penetration). Each of these spray forms and reach (penetration) changes depending on the surrounding pressure (back pressure). When the in-cylinder pressure (back pressure) increases, the spray angle and the penetration basically decrease. Conversely, when the in-cylinder pressure (back pressure) decreases, the spray angle and the penetration basically increase. In the low-speed low-load region, as described above, a sufficient gas flow cannot be obtained, so that it is necessary to lower the in-cylinder pressure to secure a certain amount of penetration. On the other hand, when the load increases,
The injection volume increases, the penetration increases inherently,
In addition, since the concentration in the spray also increases, it is necessary to suppress the spray and stratify by applying a higher back pressure.

FIG. 8 shows an example of the opening / closing timing of the intake valve, the opening / closing timing of the exhaust valve, the operation timing of the injection valve, and the ignition timing.
Three examples of low-speed medium load and medium-speed medium load are shown. As shown in this figure, in the first embodiment, the intake valve closing timing (IVC) is after the bottom dead center, and at low speed and low load,
It is retarded so as to increase the penetration, that is, to lower the actual compression ratio. On the other hand, when the load is low and medium, the penetration is inherently high. Therefore, the IVC is advanced to increase the actual compression ratio. In the middle speed range where the engine speed is higher than in the low speed range, the IVC is relatively retarded.

On the other hand, the request for the intake valve opening timing (IVO)
As described above, in response to the requirement of the internal EGR rate, in the stratified combustion, the oxygen concentration of the exhaust gas is decreased due to the increase in the fuel amount with the increase in the load, and at the same time, the stratified combustible portion is reduced. In this embodiment, the IVO is controlled to be substantially constant irrespective of the level of the load, since the equivalent ratio increases to the lean side.

Next, FIG. 9 shows a map of the request IVC in the second embodiment, and FIG. 10 shows a diagram similar to FIG. 8 in the second embodiment.

In the second embodiment, the intake valve closing timing (I
VC) is set to be more advanced than the bottom dead center, and is closed during the intake stroke to control the actual compression ratio. Note that the intake valve opening timing, that is, the valve overlap, is the same as in the above-described embodiment.

Even with such IVC control, the actual compression ratio can be controlled in consideration of the penetration.
In particular, due to heat flowing into the cylinder after the intake valve is closed, atomization of the fuel is further promoted, and the unburned rate at low load can be reduced.

In FIG. 10, the intake valve opening / closing timing at the time of homogeneous combustion on the high load side is additionally shown for reference. The requirement of the homogeneous combustion region is substantially determined by the WOT requirement, and the IVC substantially reaches the bottom dead center at extremely low rotation, and the retardation is retarded as the rotation increases. In addition, the request for IVO requires that the angle be advanced to such an extent that the residual gas does not excessively increase. Therefore, the valve opening period of the homogeneous region is 180 ° CA or more.

On the other hand, the opening period of the intake valve during stratified combustion is 180 ° CA or less.

Next, FIG. 11 shows a map of the request IVC in the third embodiment, and FIG. 12 shows a diagram similar to FIG. 8 in the third embodiment.

The third embodiment is characterized in that the exhaust valve 58 is also provided with a lift / operating angle variable mechanism and a phase variable mechanism similar to those on the intake valve side. And
In particular, during stratified combustion, the valve overlap is set to minus overlap. The variable valve mechanism on the exhaust valve side has the same configuration as that on the intake valve side described above, and a description thereof will be omitted.

FIG. 13 is a flowchart showing the flow of the control of the variable valve mechanism on the exhaust valve side. This is the same as FIG. 6 described above.
, The engine operating conditions such as the engine speed, load, oil temperature, water temperature, etc. are fetched, and in step 112, it is determined whether or not the engine is in a region where stratified combustion operation is to be performed. If it is determined that the combustion area is in the stratified combustion region, in the next step 113, the required exhaust valve closing timing (required EVC) is referred to from the map value according to the rotational speed and the load. The required exhaust valve closing timing may be calculated based on the intake valve opening timing at that time so that a predetermined minus overlap is obtained.

In the following step 114, the required exhaust valve opening timing (required EVO) is similarly read with reference to a map.
Then, in step 115, the request EVC and the request E
The required operating angle and phase are obtained from VO and step 11
At 6, these values are set.

As is clear from FIG. 12, during stratified combustion,
With the negative overlap, the temperature of the internal EGR gas is prevented from lowering, and the temperature in the cylinder increases. Thereby, atomization of the spray is promoted, and the unburned rate is further reduced. Further, the atomization can shorten the combustion period and increase the isocapacity.

When the negative overlap is made as described above, as shown in FIG. 14, a period a from the exhaust valve closing timing to the top dead center and a period b from the top dead center to the intake valve opening timing b Are in a relationship of b> a. As a result, the characteristics shown in the schematic PV diagram in FIG. 15 are obtained, the negative pressure increases in the early stage of the intake stroke, the gas flow is strengthened, and the in-cylinder temperature further increases.

On the other hand, the required EVO is discharged for a long time in a stratified state with a low rotational speed, for example. Therefore, setting it near the bottom dead center increases the expansion work, which leads to further improvement in efficiency. The required EVO is set to advance as the rotational speed increases.

FIG. 16 shows a comparison between the opening timing and the closing timing of the intake and exhaust valves in each embodiment, and particularly shows the characteristics at low speed and low load such as idle.

FIG. 17 shows a change in the opening timing of the intake valve due to a change in the load in the first embodiment.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a variable valve mechanism used in a direct injection type internal combustion engine according to the present invention.

FIG. 2 is a sectional view showing a lift / operating angle variable mechanism.

FIG. 3 is a characteristic diagram showing a characteristic change of a lift / operating angle by a lift / operating angle variable mechanism.

FIG. 4 is a characteristic diagram showing a phase change of a valve lift characteristic by a variable phase mechanism.

FIG. 5 is a sectional view showing the configuration of the entire in-cylinder direct injection internal combustion engine.

FIG. 6 is a flowchart showing control of an intake valve side variable valve mechanism.

FIG. 7 is a map of a request IVC in the first embodiment.

FIG. 8 is a time chart showing intake valve opening / closing timing and the like in the first embodiment.

FIG. 9 is a map of a request IVC in the second embodiment.

FIG. 10 is a time chart showing intake valve opening / closing timing and the like in a second embodiment.

FIG. 11 is a map of a request IVC in the third embodiment.

FIG. 12 is a time chart showing intake valve opening / closing timing and the like in a third embodiment.

FIG. 13 is a flowchart illustrating control of an exhaust valve-side variable valve mechanism according to a third embodiment.

FIG. 14 is a valve timing diagram according to the third embodiment.

FIG. 15 is a PV diagram according to the third embodiment.

FIG. 16 is a valve timing diagram showing a comparison between the opening timing and the closing timing of the intake and exhaust valves of the embodiments.

FIG. 17 is a valve timing diagram showing a change in the opening timing of the intake valve due to a load change in the first embodiment.

[Explanation of symbols]

 1: Variable lift / operating angle mechanism 2: Variable phase mechanism 33: Engine control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 320 F02D 41/04 320 41/08 320 41/08 320 43/00 301 43/00 301E 301Z 301G 45/00 301 45/00 301H 312 312C F-term (reference) 3G018 AA00 AB07 AB16 BA01 BA11 CA07 DA04 DA08 EA02 EA03 EA04 EA11 EA17 EA31 EA32 EA35 FA01 FA06 FA07 FA08 FA26 FA27 GA07 GA08 3G084 BA09 BA03 BA10 FA18 FA20 FA31 FA33 FA38 3G092 AA01 AA06 AA09 AA11 BA04 BA09 BB06 DA05 EC10 FA05 GA04 HA06Z HE01Z HE03Z HE06Z HE08Z HF08Z 3G301 HA01 HA04 HA19 JA04 KA07 MA01 MA11 MA18 NC04 PA11Z PA17Z PE01Z PE03Z08

Claims (14)

[Claims] An ignition plug is disposed substantially at the center of a combustion chamber recessed on a cylinder head side, and a shallow dish-shaped combustion chamber is recessed on a crown surface of a piston along a forward tumble flow. A fuel injection valve is arranged below the intake port so as to inject fuel in a direction obliquely downward with respect to the cylinder center line, and a part of the spray injected from the fuel injection valve is transmitted to the ignition plug. A lift / operating angle variable mechanism for changing an operating angle and a lift amount while keeping a center of an operating angle of an intake valve substantially constant in an in-cylinder direct injection type internal combustion engine configured to go straight; A direct-injection type internal combustion engine, comprising: a variable phase mechanism that changes the phase of the fuel injection; and performing valve lift control to optimize the penetration of spray during stratified combustion. 2. In stratified charge combustion, the opening timing of the intake valve is advanced and the closing timing is retarded, as compared with homogeneous combustion.
2. The direct injection internal combustion engine according to claim 1, wherein the closing timing of the exhaust valve is not changed. 3. In stratified charge combustion, the opening timing of the intake valve is advanced, the closing timing is advanced from the bottom dead center, and the closing timing of the exhaust valve is not changed as compared with homogeneous combustion. The in-cylinder direct injection internal combustion engine according to claim 1, wherein: 4. An in-cylinder direct injection internal combustion engine according to claim 1, wherein the operating angle and lift of the intake valve are controlled to be smaller during stratified charge combustion than during homogeneous charge combustion. 5. In stratified charge combustion, the opening timing of the intake valve is advanced without changing the closing timing of the exhaust valve, and the closing timing of the intake valve after the bottom dead center is changed without changing the closing timing of the exhaust valve. 2. An in-cylinder direct injection internal combustion engine according to claim 1, wherein the internal combustion engine is advanced with the rise. 6. An in-cylinder direct injection internal combustion engine according to claim 3, wherein the advance amount from the bottom dead center of the closing timing of the intake valve at the time of stratified combustion decreases as the load increases. 7. An in-cylinder direct injection internal combustion engine according to claim 3, wherein the operating angle and lift amount of the intake valve during stratified charge combustion increase as the engine speed increases. 8. An in-cylinder direct injection internal combustion engine according to claim 5, wherein the opening timing of the intake valve during stratified combustion is substantially constant regardless of the load. 9. The variable lift / operating angle mechanism according to claim 1, wherein the maximum positive acceleration of the intake valve is reduced when the operating angle / lift amount is reduced. An in-cylinder direct injection internal combustion engine according to claim 1. 10. The engine according to claim 1, wherein at the time of idling stratified combustion, the opening timing of the intake valve is retarded from the top dead center, and the closing timing is retarded at the time of idle homogeneous combustion.
An in-cylinder direct injection internal combustion engine according to claim 1. 11. A lift / operating angle variable mechanism on the exhaust valve side for changing the operating angle and the lift amount while keeping the operating angle center of the exhaust valve substantially constant, and the exhaust valve side for changing the phase of the operating angle center. The in-cylinder direct injection internal combustion engine according to claim 1, further comprising: a variable phase mechanism. 12. During stratified charge combustion, the exhaust valve closing timing is advanced from the top dead center and the intake valve opening timing is delayed from the top dead center to make a negative overlap. Item 12. An in-cylinder direct injection internal combustion engine according to item 11. 13. An in-cylinder direct injection internal combustion engine according to claim 12, wherein a period from the top dead center to the intake valve opening timing is longer than a period from the exhaust valve closing timing to the top dead center. 14. The lift / operating angle variable mechanism is provided in parallel with the drive shaft, an eccentric cam rotatably driven by a drive shaft, a link arm fitted to the outer periphery of the eccentric cam so as to be relatively rotatable. A rotatable control shaft having an eccentric cam portion, a rocker arm rotatably mounted on the eccentric cam portion of the control shaft and swinging by the link arm, and rotatably supported by the drive shaft. As well as
A swing cam that is connected to the rocker arm via a link and swings along with the rocker arm to press the intake valve, thereby changing a rotation position of the eccentric cam portion of the control shaft. The direct-injection internal combustion engine according to any one of claims 1 to 13, wherein the operating angle and the lift of the intake valve are simultaneously increased and decreased.