JP2003247443A - Internal combustion engine with variable shift valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize fuel injection timing in terms of fuel atomization or the like for variable control of lifting amount in a constitution for intake port injection. <P>SOLUTION: An engine is provided with a lift/actuation angle varying mechanism continuously varying the lift/actuation angle of a suction valve and a phase varying mechanism continuously varying the phase of lifting center angle, and the amount of intake is controlled by the variable control of a valve lift characteristic. The fuel injection valve is disposed on an intake port and injects the fuel into the suction valve. In a range of a small lifting amount, intake stroke injection is selected because flow velocity near the suction valve is high. In a range of a large lifting amount, the suction valve is switched to waiting time injection in which injection is finished before the valve is opened in order to secondarily atomize the fuel by heat near the intake port because flow velocity near the suction valve becomes lower. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine equipped with a variable valve mechanism for variably controlling the lift amount or operating angle of an intake valve and a fuel injection valve upstream of the intake valve.

[0002]

2. Description of the Related Art In an internal combustion engine equipped with a variable valve mechanism capable of changing the lift characteristic of an intake valve and injecting fuel into an intake passage upstream of the intake valve, the variable valve mechanism is controlled. A technique for adjusting the fuel injection timing in accordance with this is disclosed in Japanese Patent Laid-Open No. 2001-221083.

In this prior art, the valve overlap amount is increased by changing the center phase of the lift center angle of the intake valve on the premise that the fuel injection is completed before the intake valve is opened. Sometimes, the fuel injection timing is retarded.

A variable valve mechanism for continuously variably controlling the lift amount of the intake valve is known from Japanese Patent Laid-Open No. 8-260923.

[0005]

In the case of an internal combustion engine equipped with a variable valve mechanism capable of changing the lift amount of the intake valve, the flow velocity of intake air near the intake valve changes significantly depending on the control state of the variable valve device. . For example, if the lift amount is small, the flow velocity in the annular passage of the intake valve will be high. Therefore, it is important to perform fuel injection that effectively utilizes this flow velocity change.

In the above-mentioned prior art, no study has been made on the fuel injection timing control when the lift amount of the intake valve is changed.

[0007]

An internal combustion engine according to the present invention comprises a variable valve mechanism for variably controlling the lift amount (maximum lift amount) of its intake valve. In this variable valve mechanism,
A second variable valve mechanism that can change the phase of the lift center angle of the intake valve can be further combined.

The fuel injection valve is arranged upstream of the intake valve and injects fuel into the intake passage. Desirably, this fuel injection valve has a conical spray form, and is configured such that the outer peripheral portion of the spray overlaps the seal portion on the outer peripheral surface of the intake valve.

The fuel injection timing of this fuel injection valve is
According to the present invention, the first injection timing, which is controlled by the control device and ends the fuel injection before the intake valve opens, and the second injection timing, which performs the fuel injection during the opening period of the intake valve, can be set as described above. It is adapted to be selected according to the control state of the variable valve mechanism.

More specifically, when the lift amount of the intake valve is larger than the predetermined lift amount, the first injection timing is selected,
The second injection timing is selected when the lift amount of the intake valve is smaller than the predetermined lift amount.

When the lift amount is large, the fuel injection is terminated before the intake valve opens (hereinafter referred to as waiting time injection) as the first injection timing, so that the heat of the intake valve and the intake port is reduced. Can accelerate the vaporization of fuel.
That is, secondary atomization of the fuel can be achieved. On the other hand, when the lift amount is small, fuel injection is performed during the opening period of the intake valve as the second injection timing (hereinafter, this is referred to as intake stroke injection).
As a result, it is possible to avoid variations in the degree of adhesion of fuel to the intake port, and consequently variations in the intake air amount due to the influence thereof. In other words, in the state where the lift amount is small and the flow passage area of the opening is small, the substantial flow passage area changes greatly when the fuel adhesion degree changes. Cycle variation is suppressed.

When the lift amount is large, even if the fuel adhesion degree varies, the change in the flow passage area of the opening due to the variation is a small ratio from the overall flow passage area, and the influence on the intake air amount is large. Does not matter. Also,
When the lift amount is small, the intake flow velocity when passing through the intake valve becomes large, and the fuel is atomized by the flow. Therefore, there is no problem even if the secondary atomization action due to heat such as waiting time injection is not given.

[0013]

According to the present invention, the waiting time injection capable of secondary atomization due to heat and the intake stroke injection capable of suppressing the variation in the degree of fuel adhesion are controlled according to the variable control of the intake valve lift amount. It can be optimal.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment in which the present invention is configured as a spark ignition type gasoline engine for an automobile will be described.

FIG. 1 is a structural explanatory view showing the structure of an intake valve side variable valve operating device of an internal combustion engine. This variable valve operating device is
As a variable valve mechanism, a lift / operating angle variable mechanism 1 for changing a lift / operating angle of an intake valve, and a phase variable for advancing or retarding a phase of a central angle of the lift (phase with respect to a crankshaft not shown). And a mechanism 21 (corresponding to a second variable valve mechanism).

First, the lift / operating angle varying mechanism 1 will be described. The lift / operating angle variable mechanism 1 was previously proposed by the present applicant, and is disclosed in, for example, Japanese Patent Laid-Open No. 11-10.
Since it is known from Japanese Patent Publication No. 7725, only its outline will be described.

The variable lift / operating angle mechanism 1 includes an intake valve 11 slidably mounted on a cylinder head (not shown).
And a cam bracket on the top of the cylinder head (not shown)
The drive shaft 2 rotatably supported by the
An eccentric cam 3 fixed by press fitting and the like, and a control shaft 12 rotatably supported by the same cam bracket above the drive shaft 2 and arranged parallel to the drive shaft 2.
The rocker arm 6 swingably supported by the eccentric cam portion 18 of the control shaft 12 and the swing cam 9 that abuts the tappet 10 arranged at the upper end portion of each intake valve 11. The eccentric cam 3 and the rocker arm 6 are linked by a link arm 4, and the rocker arm 6 and the swing cam 9 are linked by a link member 8.

The drive shaft 2 is driven by the crankshaft of the engine via a timing chain or timing belt, as will be described later.

The eccentric cam 3 has a circular outer peripheral surface, and the center of the outer peripheral surface is offset from the axial center of the drive shaft 2 by a predetermined amount, and the annular portion of the link arm 4 is formed on the outer peripheral surface. It is rotatably fitted.

The rocker arm 6 has a substantially central portion swingably supported by the eccentric cam portion 18, and one end portion of the rocker arm 6 is linked to the arm portion of the link arm 4 via a connecting pin 5. Together with the other end, the connecting pin 7
The upper end of the link member 8 is linked via the. The eccentric cam portion 18 is eccentric from the axis of the control shaft 12, and therefore the rocking center of the rocker arm 6 changes according to the angular position of the control shaft 12.

The swing cam 9 is rotatably supported by being fitted to the outer periphery of the drive shaft 2, and has an end portion extending laterally,
The lower end of the link member 8 is linked via the connecting pin 17. On the lower surface of the swing cam 9, a base circular surface that forms a circular arc concentric with the drive shaft 2 and a cam surface that extends from the base circular surface in a predetermined curve are continuously formed. The base circular surface and the cam surface come into contact with the upper surface of the tappet 10 according to the swing position of the swing cam 9.

That is, the base circle surface is a base circle section where the lift amount is 0, and the swing cam 9
When oscillates and the cam surface comes into contact with the tappet 10, it gradually lifts. A slight ramp section is provided between the base circle section and the lift section.

As shown in FIG. 1, the control shaft 12 is configured to rotate within a predetermined angle range by a lift / operating angle control actuator 13 provided at one end. This lift / operating angle control actuator 13
Is composed of, for example, a servo motor that drives the control shaft 12 via the worm gear 15, and is controlled by a control signal from the engine control unit 19 (control device). Here, the rotation angle of the control shaft 12 is detected by the control shaft sensor 14 which is an analog sensor, and the actuator 13 is closed-loop controlled based on the detected actual control state.

The operation of the lift / operating angle varying mechanism 1 will be described. When the drive shaft 2 rotates, the link arm 4 moves up and down by the cam action of the eccentric cam 3, and the rocker arm 6 swings accordingly. The swing of the rocker arm 6 is transmitted to the swing cam 9 via the link member 8, and the swing cam 9 swings. By the cam action of the swing cam 9, the tappet 10 is pressed and the intake valve 11 is lifted.

Here, when the angle of the control shaft 12 changes via the lift / operating angle control actuator 13, the center position of the rocking motion of the rocker arm 6 moves, and the initial position of the rocker arm 6 changes, which in turn rocks. The initial swing position of the moving cam 9 changes.

For example, assuming that the eccentric cam portion 18 is located above in the drawing, the rocker arm 6 is located above as a whole, and the end portion of the swing cam 9 on the connecting pin 17 side is relatively pulled up. It will be in a state of being. That is, the initial position of the swing cam 9 is tilted in the direction in which its cam surface moves away from the tappet 10. Therefore, when the oscillating cam 9 oscillates as the drive shaft 2 rotates, the base circle surface keeps contacting the tappet 10 for a long time, and the cam surface keeps contacting the tappet 10 for a short period. Therefore, the lift amount is reduced as a whole, and the angular range from the opening timing to the closing timing, that is, the operating angle is also reduced.

On the contrary, if the eccentric cam portion 18 is located downward in the figure, the rocker arm 6 is located downward as a whole, and the end of the swing cam 9 on the side of the connecting pin 17 is relatively downward. It will be pushed down. That is, the initial position of the swing cam 9 is inclined such that its cam surface approaches the tappet 10. Therefore, when the swing cam 9 swings as the drive shaft 2 rotates, the portion that comes into contact with the tappet 10 immediately shifts from the base circular surface to the cam surface. Therefore, the lift amount becomes large as a whole, and the operating angle thereof also increases.

Since the initial position of the eccentric cam portion 18 can be continuously changed, the valve lift characteristic is continuously changed accordingly. That is, as shown in FIG. 2, the lift and the working angle can be continuously expanded and contracted at the same time. Depending on the layout of each part, for example, the opening timing and the closing timing of the intake valve 11 change substantially symmetrically as the lift / operating angle changes. Note that FIG.
Shows the relationship between the rotation angle of the control shaft 12 (abbreviated as C / SFT in the drawing) and the lift / operating angle.

Next, as shown in FIG. 1, the phase varying mechanism 21 includes a sprocket 22 provided at the front end of the drive shaft 2 and the sprocket 22 and the drive shaft 2 within a predetermined angle range. And a phase control actuator 23 that relatively rotates. The sprocket 22 is interlocked with the crankshaft via a timing chain or timing belt (not shown). The phase control actuator 23 is composed of a rotary actuator such as a hydraulic type or an electromagnetic type,
It is controlled by a control signal from the engine control unit 19. This phase control actuator 2
By the action of 3, the sprocket 22 and the drive shaft 2 rotate relatively, and the lift center angle in the valve lift is retarded. In other words, the lift characteristic curve itself does not change,
The whole is advanced or retarded. Also, this change can be continuously obtained. The actual control state of the phase variable mechanism 21 is detected by the drive shaft sensor 16 which responds to the rotational position of the drive shaft 2, and the actuator 23 is closed-loop controlled based on this.

In the internal combustion engine of this embodiment equipped with such a variable valve operating device on the intake valve side, the intake amount is controlled by the variable control of the intake valve 11 without depending on the throttle valve. Incidentally, in a practical engine, it is preferable that a slight negative pressure exists in the intake system due to the circulation of blow-by gas, etc.
As described later, it is desirable to provide an appropriate throttle mechanism for generating negative pressure on the upstream side of the intake passage, instead of the throttle valve.

Explaining the intake air amount control using the lift / operating angle variable mechanism 1 and the phase variable mechanism 21, FIG. 4 shows the valve lift characteristics of the intake valve under typical operating conditions. As shown in the figure, the lift amount becomes a minimum lift in an extremely low load region such as idle. This is a small lift amount to such an extent that the phase of the lift central angle does not affect the intake amount. Then, the phase of the lift center angle by the phase changing mechanism 21 is at the most retarded position, whereby the closing timing is at the position immediately before bottom dead center.

By using the minimum lift in this way, the intake flow is choked in the gap of the intake valve 11, and the required minute flow rate can be stably obtained in the extremely low load region. Then, since the closing timing is near the bottom dead center, the effective compression ratio becomes sufficiently high, and in combination with the improvement of the gas flow due to the minimal lift, a relatively good combustion can be secured.

On the other hand, in the low load region where the load is larger than the extremely low load region such as idle (including the idle state where the auxiliary machine load is applied), the lift / operating angle becomes large and the lift center angle advances. It becomes a cornered position. At this time, the intake amount control is performed in consideration of the valve timing as well, and the intake amount is controlled to a relatively small amount by advancing the intake valve closing timing. As a result, the lift / operating angle becomes large to some extent, and the pumping loss due to the intake valve 11 is reduced.

In the extremely small lift in the extremely low load range such as idling, as described above, the intake air amount hardly changes even if the phase is changed. Therefore, when the extremely low load range is shifted to the low load range. Has priority over the phase change,
It is necessary to increase the working angle. The same applies when a load is added to auxiliary equipment such as an air conditioning compressor.

On the other hand, in the medium load range where the load further increases and the combustion becomes stable, as shown in FIG. 4, the phase of the lift central angle is advanced while the lift / operating angle is further expanded. The phase of the lift center angle is in the most advanced state at a point in the medium load range. As a result, the internal EGR is utilized, and the pumping loss can be further reduced.

Further, at the time of maximum load, the variable phase mechanism 21 is controlled so that the lift / operating angle is further expanded and the valve timing is optimized. As shown in the drawing, the optimum valve lift characteristic also differs depending on the engine speed.

FIGS. 5 and 6 show the structure of the fuel supply system of this internal combustion engine. An electromagnetic fuel injection valve 52 is arranged upstream of the intake port 51 opened and closed by the intake valve 11. The fuel is injected and supplied toward the intake valve 11. Reference numeral 53 is a negative pressure adjusting valve provided in the intake passage 55 on the upstream side for generating the negative pressure, 54 is an air cleaner, 56 is an exhaust passage, 57 is a catalytic converter, and 58 is an ignition plug. As shown in FIG. 6, the fuel injection valve 52 is configured to form a pair of conical sprays F corresponding to the pair of intake valves 11, and the outer peripheral portion of each spray F is provided with the intake valve 11. The spread of the spray is set so as to overlap the seal portion on the outer circumference of the umbrella portion.

Next, the fuel injection timing of the fuel injection valve 52 will be described.

When the lift amount of the intake valve 11 is reduced by using the lift / operating angle variable mechanism 1 as described above, the flow velocity near the seal portion of the intake valve 11 increases. Therefore, if the fuel is supplied at that time, the fuel can be atomized due to the increased air flow velocity. Therefore, during the extremely low lift of the intake valve 11, the intake stroke injection can be used relatively easily without depending on the secondary atomization due to the waiting time injection, and the injection timing can be set to the intake stroke injection according to the lift amount. It is possible to switch to and waiting time injection. In addition, when the waiting time injection is performed at an extremely low lift, the fuel droplets adhere to the vicinity of the valve seat, the fuel is supplied into the cylinder before the flow velocity develops, and the fuel particle size at the initial supply becomes large. Due to the variation in the degree of adhesion of fuel droplets, the intake valve 1
There is a possibility that the flow passage area in No. 1 changes and the amount of supplied air varies. Therefore, in the first embodiment, as shown in FIG. 7, the intake stroke injection and the waiting time injection are set by the lift amount of the intake valve 11. That is,
The intake stroke injection is performed when the lift amount is equal to or less than the predetermined lift amount, and the waiting time injection is performed when the lift amount is equal to or more than the predetermined lift amount. The lift amount is determined based on the rotation angle of the control shaft 12.

FIG. 8 is a flow chart of the first embodiment in which the injection timing is controlled based on the rotation angle of the control shaft 12. The flow of processing will be described below according to this flowchart.

First, at step 101, the control shaft 12 (in the figure,
Read the rotation angle (abbreviated as C / SFT)
At 02, it is determined whether the rotation angle is equal to or smaller than a predetermined rotation angle X corresponding to a predetermined lift amount. When the rotation angle is X or less,
In step 103, intake stroke injection is performed. In the following step 104, the advance angle amount (phase control amount) by the phase variable mechanism 21 is read. The actual valve opening timing and valve opening period of the intake valve 11 are calculated from the control axis angle and the phase control amount. In the following step 105, the fuel injection start timing is set roughly in step 10 in order to surely perform the intake stroke injection.
It is determined as the intake valve opening start timing calculated in step 4, and fuel is injected into the intake port for the fuel injection period corresponding to the air amount.

On the other hand, in step 102, a predetermined rotation angle X
If it is determined to be greater than, go to step 106,
It is a waiting time injection. In the following step 107, the phase control amount by the phase variable mechanism 21 is read, and the actual valve opening timing and valve opening period of the intake valve 11 are calculated from the control axis angle and the phase control amount. In the following step 108,
In order to reliably perform the waiting time injection, the fuel injection end timing is set to be earlier than the intake valve opening start timing calculated in step 107, and the injection start is performed at a timing that is traced back by a necessary fuel injection period according to the air amount. As the timing, fuel injection is executed.

FIG. 9 is a timing chart showing a comparison between the intake stroke injection and the waiting time injection.

In this way, by making the intake stroke injection to the intake valve low lift, the fuel atomization effect due to the high intake flow velocity near the seal portion of the intake valve 11 can be effectively utilized, and the unburned fuel can be reduced. At the same time, the adhesion of fuel to the intake port 51 is suppressed, the fuel arrival delay during transition and the cycle variation with respect to the set air-fuel ratio can be reduced, and the exhaust performance and the drivability can be improved. Moreover, by making the cone-shaped fuel spray correspond to the outer diameter of the intake valve 11, the fuel adhesion is further suppressed. Further, when the intake valve is in a high lift state where the flow velocity near the seal portion is low, by performing the waiting time injection, secondary atomization using the heat of the intake port 51 and the intake valve 11 can be achieved and a homogeneous air-fuel mixture can be obtained. You can

Next, a second embodiment corresponding to claim 3 will be described with reference to FIGS.

In this embodiment, in addition to the first embodiment, the fuel injection timing is switched in consideration of the engine rotation speed. As shown in FIG. The intake stroke injection and the waiting time injection are selectively set using the amount and the engine speed as parameters. That is, basically, the intake stroke injection is performed below the predetermined lift amount, and the waiting time injection is performed above the predetermined lift amount,
As the rotation speed increases, the value of the predetermined lift amount that is the switching point increases.

This is because even if the lift amount is the same as the rotation speed increases, the intake valve 1 is
This is because it is considered that the differential pressure before and after 1 increases, and as a result, the air flow velocity increases. In other words,
As the engine speed increases, the valve lift amount at which the air velocity becomes the same can be increased. The intake valve 11
In the region where the flow in the gap between the valve seat and the valve seat is already choked, the flow velocity in this part does not change, but the flow velocity in the cylinder increases due to the decrease in in-cylinder density. Can be achieved.

Explaining in accordance with the flowchart of FIG. 11, in step 111, the rotation angle of the control shaft 12 (C / SFT) and the engine rotation speed are read, and in step 112, a determination map showing the region where the intake stroke injection should be performed. Refer to. This map has the characteristics shown in FIG. Then, in step 113, it is determined based on this map whether or not the region is where the intake stroke injection is performed. If it is the region where the intake stroke injection is to be performed, step 11
4, and the intake stroke injection is performed. In the following step 115, the phase control amount by the phase variable mechanism 21 is read, and the intake valve opening timing and the valve opening period are calculated from the control axis angle and the phase control amount. In the following step 116, in order to reliably perform the intake stroke injection, the fuel injection start timing is obtained as the intake valve opening start timing calculated in the rough step 115, and the fuel is injected into the intake port for the fuel injection period corresponding to the air amount. To inject.

On the other hand, if it is determined in step 113 that the region is not the intake stroke injection, step 117
Proceed to and start the waiting time injection. In the following step 118, the phase control amount by the phase variable mechanism 21 is read, and the actual valve opening timing and valve opening period of the intake valve 11 are calculated from the control axis angle and the phase control amount. Continued Step 11
In No. 9, in order to surely perform the waiting time injection, the fuel injection end timing is before the intake valve opening start timing calculated in step 118, and the timing is traced back by the necessary fuel injection period according to the air amount. The fuel injection is executed with the injection start timing as.

Therefore, as shown in FIG. 10, as the rotational speed increases, the limit lift amount that allows intake stroke injection increases, and the operating range in which the atomization effect due to the high flow velocity is obtained increases.

Next, a third embodiment corresponding to claim 4 will be described with reference to FIGS.

In this embodiment, in addition to the intake valve lift amount,
The fuel injection timing is set in consideration of the advance amount of the intake valve lift central angle by the phase variable mechanism 21. That is, as shown in FIG. 12, basically, the intake stroke injection is performed below the predetermined lift amount, and the waiting time injection is performed above the predetermined lift amount. Further, in the case of the intake stroke injection, the phase control amount and Based on the lift amount, the injection start timing is selected to be the approximate intake valve opening start timing or the intake top dead center of the piston. As shown in the figure, in a region where the intake valve lift center angle is greatly advanced, the injection start timing is set to approximately the intake top dead center.

This means that when the intake valve 11 is opened during the exhaust stroke, burned gas is blown back from the inside of the cylinder to the intake port 51, and at that time, fuel is injected toward the intake valve 11. This is because the fuel spray may be blown back to the upstream side together with the blown back gas. When the fuel is blown back, as in the case of the waiting time injection, the fuel is likely to adhere to the inner wall surface of the port, cycle variation, and the like.
Therefore, in the present embodiment, the valve overlap is determined from the intake valve lift amount and the phase control amount (advance amount) of the intake valve lift center angle, and fuel is not injected during the valve overlap. is there.

Explaining in accordance with the flowchart of FIG. 13, first, in step 131, the turning angle of the control shaft 12 (C / SFT) is read together with the phase control amount of the phase changing mechanism 21, and in step 132, the turning angle is equal to or less than the predetermined turning angle X. Determine if there is. If the rotation angle is equal to or smaller than the predetermined rotation angle X, the routine proceeds to step 133, where intake stroke injection is performed.

In the following step 134, the injection start timing correction map is referred to. At the same time, the intake valve opening timing and the valve opening period are calculated from the control axis angle and the phase control amount. In the following step 135, it is determined whether or not the fuel injection start timing should be corrected to the intake top dead center based on the injection start timing correction map set to the characteristic shown in FIG. When it is determined that the correction is unnecessary, the process proceeds to step 137, and the injection is executed with the fuel injection start timing as the intake valve opening start timing, as in the first embodiment. Also, step 135
If it is determined that the fuel injection start timing needs to be corrected, the routine proceeds to step 136, where injection is performed with the fuel injection start timing as the intake top dead center of each cylinder.

On the other hand, in step 132, the predetermined rotation angle X
When it is determined that the above is the case, the process proceeds to step 138, the waiting time injection is performed, and the intake valve opening timing and the valve opening period are calculated from the control axis angle and the phase control amount. In the following step 139, the fuel injection end timing is set to be earlier than the intake valve opening start timing calculated in step 138 and the necessary fuel injection period is traced back in accordance with the air amount in order to reliably perform the waiting time injection. The fuel injection is performed with the injection start timing set at the above timing.

Therefore, as shown in FIG. 12, when the lift amount is equal to or less than the predetermined lift amount, the intake stroke injection is performed, and when the blowback gas is generated due to the valve overlap, the fuel injection should be started from the intake top dead center. Therefore, it is possible to avoid the blowback of the spray in the intake stroke injection. The heat of the blowback gas can be used for atomizing the fuel while avoiding the blowback of the spray.

Next, a fourth embodiment disclosing the contents of claim 5 will be described with reference to FIGS. 14 and 15. The fourth embodiment is based on the third embodiment, and the limit lift amount for performing the intake stroke injection is changed according to the phase control amount of the phase variable mechanism 21.

When the valve overlap is set to a negative value, the inside of the cylinder adiabatically expands during the intake stroke and the pressure drops. As mentioned above, when the lift is low, the operating angle becomes small at the same time.
When the control state of the phase variable mechanism 21 is on the retard side, the valve overlap becomes negative and adiabatic expansion occurs. In such a case, the differential pressure between the intake port 51 and the cylinder increases, and the flow velocity at the start of the intake valve lift increases, so as shown in FIG.
It can be set higher on the retard side.

Further, although the valve overlap becomes positive in the region where the phase variable mechanism 21 advances to some extent, when there is such valve overlap, if the phase of the intake valve lift is further advanced, the internal EGR is generated. Since the amount of burnt gas increases, the heat supplied to the intake air increases. Therefore, as shown in FIG. 14, the vaporization of the fuel is promoted toward the advance side, and the lift amount that can be injected in the intake stroke can be set higher.

The outline of the processing flow of this embodiment will be described with reference to the flowchart of FIG.
At step 152, the rotation angle of the control shaft 12 and the phase control amount of the phase changing mechanism 21 are read, and at step 152, a predetermined map for determining the fuel injection timing is determined from the rotation angle of the control shaft 12 and the phase control amount. refer. Note that this map is basically created in advance according to the characteristics shown in FIG. In the following step 153, the fuel injection timing is determined based on the referenced map, and the injection is executed. As in each of the above-described embodiments, in the case of the waiting time injection, the injection start timing is obtained from the injection end timing. According to this embodiment, as shown in FIG. 12, as the advance amount of the phase variable mechanism 21 increases, the limit lift amount that allows intake stroke injection is given as high as possible.

It is desirable that the injection start timing in the present invention considers the invalid pulse width generated when the injection valve is driven. Further, since the arrival timing of the fuel spray is the most important, it is more desirable to set the fuel injection start timing in consideration of the arrival time of the spray from the injection valve mounting position to the intake valve.

[Brief description of drawings]

FIG. 1 is a perspective view showing the overall configuration of a variable valve operating device used in an internal combustion engine of the present invention.

FIG. 2 is a lift characteristic diagram showing a state of changes in lift / operating angle.

FIG. 3 is a characteristic diagram showing a relationship between a rotation angle of a control shaft and a lift / operating angle.

FIG. 4 is a characteristic diagram showing valve lift characteristics under typical operating conditions.

FIG. 5 is an explanatory diagram of an internal combustion engine showing a fuel supply system.

FIG. 6 is an explanatory view showing a spray shape of a fuel injection valve.

FIG. 7 is a characteristic diagram showing a characteristic of switching between intake stroke injection and waiting time injection with respect to a lift amount in the first embodiment.

FIG. 8 is a flowchart showing a flow of processing according to the first embodiment.

FIG. 9 is a time chart showing a comparison between intake stroke injection and waiting time injection.

FIG. 10 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the second embodiment.

FIG. 11 is a flowchart showing the flow of processing according to the second embodiment.

FIG. 12 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the third embodiment.

FIG. 13 is a flowchart showing the flow of processing in the third embodiment.

FIG. 14 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the fourth embodiment.

FIG. 15 is a flowchart showing the flow of processing according to the fourth embodiment.

[Explanation of symbols]

1 ... Lift / Operating angle variable mechanism 2 ... Drive shaft 3 ... Eccentric cam 6 ... Rocker arm 8 ... Link member 9 ... Swing cam 11 ... Intake valve 12 ... Control axis 14 ... Control axis sensor 16 ... Drive axis sensor 19 ... Engine control unit 21 ... Phase variable mechanism 52 ... Fuel injection valve

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 69/04 F02M 69/04 R (72) Inventor Tsuneyasu Nohara 2 Takara-cho, Kanagawa-ku, Kanagawa Prefecture Nissan Motor Co., Ltd. Inner F term (reference) 3G018 AB05 AB17 BA02 BA09 BA19 BA32 DA01 DA12 DA19 FA06 FA07 GA08 3G092 AA01 AA11 BB06 DA05 DE01S EC01 FA08 3G301 HA01 HA09 HA19 JA12 LA01 LA07 LB02 LC01 MA19 ND03 NE11 NE12 PA17Z PE01Z PE03Z PE08 PE03Z PE08

Claims (7)

[Claims] 1. A variable valve mechanism capable of changing a lift amount of an intake valve, a fuel injection valve for injecting fuel into an intake passage, and a first injection timing for ending fuel injection before the intake valve opens. And a control device that selects a second injection timing for injecting fuel during the opening period of the intake valve according to the control state of the variable valve mechanism, and an internal combustion engine with a variable valve mechanism. 2. The control device selects the first injection timing when the lift amount of the intake valve is larger than a predetermined lift amount, and the second injection timing when the lift amount of the intake valve is smaller than the predetermined lift amount. 2. The method according to claim 1, wherein
An internal combustion engine with a variable valve mechanism according to. 3. The internal combustion engine with a variable valve mechanism according to claim 2, wherein the value of the predetermined lift amount increases as the rotation speed of the internal combustion engine increases. 4. A second variable valve mechanism capable of changing the phase of the lift center angle of the intake valve is further provided, and a control state of the second variable valve mechanism is predetermined when the second injection timing is selected. The internal combustion engine with a variable valve mechanism according to claim 2, wherein the fuel injection is started after the intake top dead center when it is on the advance side of the phase. 5. The internal combustion engine with a variable valve mechanism according to claim 4, wherein the value of the predetermined lift amount increases with the advance of the control state of the second variable valve mechanism. . 6. The variable valve 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 control shaft provided with an eccentric cam part and rotatable within at least a predetermined angle range, a rocker arm rotatably mounted on the eccentric cam part of the control shaft and swung by the link arm, and rotated on the drive shaft. A swing cam that is supported movably, is connected to the rocker arm via a link, and swings with the rocker arm to press the intake valve, and a lift / operating angle that changes the rotational position of the control shaft. A control actuator, and the lift of the intake valve is configured to increase or decrease with the operating angle thereof depending on the rotational position of the eccentric cam portion of the control shaft. An internal combustion engine with a variable valve mechanism according to any one of claims 1 to 5. 7. The fuel injection valve has a conical spray form, and is configured such that an outer peripheral portion of the spray overlaps a seal portion on an outer periphery of the intake valve.
An internal combustion engine with a variable valve mechanism according to any one of 1.