JP3815345B2 - Internal combustion engine with variable valve mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine that includes a variable valve mechanism that variably controls the lift amount or operating angle of an intake valve, and that includes a fuel injection valve upstream of the intake valve.
[0002]
[Prior art]
In an internal combustion engine that includes a variable valve mechanism that can change the lift characteristics of the intake valve and that injects and supplies fuel into an intake passage upstream of the intake valve, the fuel injection timing according to the control state of the variable valve mechanism Japanese Patent Application Laid-Open No. 2001-221083 discloses a technique for adjusting the above.
[0003]
In this prior art, when the valve overlap amount becomes large by changing the lift center angle phase of the intake valve on the premise that the fuel injection is terminated before the intake valve is opened, and the lift center angle phase of the intake valve is changed, The fuel injection timing is retarded.
[0004]
Japanese Patent Laid-Open No. 8-260923 discloses a variable valve mechanism that continuously and variably controls the lift amount of an intake valve.
[0005]
[Problems to be solved by the invention]
In the case of an internal combustion engine provided with a variable valve mechanism that can change the lift amount of the intake valve, the flow velocity of intake air in the vicinity of the intake valve varies greatly depending on the control state of the variable valve device. For example, when the lift amount is small, the flow velocity in the annular flow path of the intake valve becomes large. Therefore, it is important to perform fuel injection that effectively utilizes this change in flow velocity.
[0006]
In the above prior art, no study is made on the fuel injection timing control when changing the lift amount of the intake valve.
[0007]
[Means for Solving the Problems]
The internal combustion engine according to the present invention includes a variable valve mechanism that variably controls the lift amount (maximum lift amount) of the intake valve. This variable valve mechanism can be further combined with a second variable valve mechanism that can change the phase of the lift central angle of the intake valve.
[0008]
The fuel injection valve is disposed on the upstream side 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 periphery of the intake valve.
[0009]
The fuel injection timing of the fuel injection valve is controlled by the control device. In the present invention, the fuel injection timing is terminated before the intake valve opens, and the fuel injection is performed during the intake valve opening period. The second injection timing to be performed is selected according to the control state of the variable valve mechanism.
[0010]
More specifically, the first injection timing is selected when the lift amount of the intake valve is larger than a predetermined lift amount, and the second injection timing is selected when the lift amount of the intake valve is smaller than the predetermined lift amount. Then, the value of the predetermined lift amount increases as the rotational speed of the internal combustion engine increases.
[0011]
When the lift amount is large, the fuel injection is terminated before the intake valve opens as the first injection timing (hereinafter referred to as waiting time injection), so that the heat of the intake valve and the intake port Vaporization can be promoted. That is, secondary atomization of the fuel can be achieved. On the other hand, when the lift amount is small, the fuel injection is performed during the intake valve opening period as the second injection timing (hereinafter referred to as intake stroke injection), thereby causing a variation in the degree of fuel adhesion to the intake port, As a result, variation in intake air amount due to the influence can be avoided. In other words, in a 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.
[0012]
When the lift amount is large, even if the degree of fuel adhesion varies, the change in the flow path area of the opening due to this is a slight ratio from the overall flow path area, and the influence on the intake air amount is a problem. Don't be. Also, when the lift amount is small, the intake flow velocity when passing through the intake valve increases, and the fuel is atomized by the flow, so there is no problem even if the secondary atomization effect due to heat such as waiting time injection is not given Absent.
[0013]
【The invention's effect】
According to the present invention, the waiting time injection that enables secondary atomization by heat and the intake stroke injection that can suppress the variation in the degree of fuel adhesion are optimized in accordance with the variable control of the intake valve lift amount. be able to.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is configured as a spark ignition gasoline engine for an automobile will be described.
[0015]
FIG. 1 is a configuration explanatory view showing the configuration of an intake valve side variable valve operating device of an internal combustion engine. This variable valve operating device serves as a variable valve operating mechanism for changing the lift / operating angle of an intake valve. A variable angle mechanism 1 and a phase variable mechanism 21 (corresponding to a second variable valve mechanism) that advances or retards the phase of the center angle of the lift (phase with respect to a crankshaft (not shown)). Yes.
[0016]
First, the lift / operating angle variable mechanism 1 will be described. The lift / operating angle variable mechanism 1 has been previously proposed by the applicant of the present application. However, since it has been publicly known, for example, in Japanese Patent Application Laid-Open No. 11-107725, only the outline thereof will be described.
[0017]
The variable lift / operating angle mechanism 1 includes an intake valve 11 slidably provided on a cylinder head (not shown) and a drive shaft 2 rotatably supported by a cam bracket (not shown) on the cylinder head. And an eccentric cam 3 fixed to the drive shaft 2 by press-fitting or the like, and a control shaft 12 that is rotatably supported by the same cam bracket at a position above the drive shaft 2 and arranged in parallel with the drive shaft 2. And a rocker arm 6 that is swingably supported by the eccentric cam portion 18 of the control shaft 12, and a swing cam 9 that contacts the tappet 10 disposed at the upper end 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.
[0018]
As will be described later, the drive shaft 2 is driven by a crankshaft of an engine via a timing chain or a timing belt.
[0019]
The eccentric cam 3 has a circular outer peripheral surface, and the center of the outer peripheral surface is offset from the shaft center of the drive shaft 2 by a predetermined amount, and the annular portion of the link arm 4 is rotatable on the outer peripheral surface. It is mated.
[0020]
The rocker arm 6 has a substantially central portion supported by the eccentric cam portion 18 so as to be swingable, and an arm portion of the link arm 4 is linked to one end portion thereof via a connecting pin 5. The upper end portion of the link member 8 is linked to the end portion via the connecting pin 7. The eccentric cam portion 18 is eccentric from the axis of the control shaft 12, and accordingly, the rocking center of the rocker arm 6 changes according to the angular position of the control shaft 12.
[0021]
The rocking cam 9 is fitted to the outer periphery of the drive shaft 2 and is rotatably supported, and the lower end portion of the link member 8 is linked to the end portion extending sideways via a connecting pin 17. ing. On the lower surface of the swing cam 9, a base circle surface concentric with the drive shaft 2 and a cam surface extending in a predetermined curve from the base circle surface are continuously formed. These base circle surface and cam surface are in contact with the upper surface of the tappet 10 according to the swing position of the swing cam 9.
[0022]
That is, the base circle surface is a section where the lift amount becomes 0 as a base circle section, and when the swing cam 9 swings 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.
[0023]
As shown in FIG. 1, the control shaft 12 is configured to rotate within a predetermined angle range by a lift / operation angle control actuator 13 provided at one end. The lift / operating angle control actuator 13 includes, for example, a servo motor that drives the control shaft 12 via the worm gear 15 and is controlled by a control signal from an engine control unit 19 (control device). Here, the rotation angle of the control shaft 12 is detected by a control shaft sensor 14 formed of an analog sensor, and the actuator 13 is closed-loop controlled based on the detected actual control state.
[0024]
The operation of the variable lift / operating angle 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. The tappet 10 is pressed by the cam action of the swing cam 9, and the intake valve 11 is lifted.
[0025]
Here, when the angle of the control shaft 12 changes via the lift / operating angle control actuator 13, the center position of the rocker movement of the rocker arm 6 moves to change the initial position of the rocker arm 6. The initial swing position of the is changed.
[0026]
For example, if the eccentric cam portion 18 is positioned upward in the figure, the rocker arm 6 is positioned upward as a whole, and the end of the swing cam 9 on the side of the connecting pin 17 is relatively lifted upward. Become. That is, the initial position of the swing cam 9 is inclined in a direction in which the cam surface is separated from the tappet 10. Therefore, when the swing cam 9 swings as the drive shaft 2 rotates, the base circle surface is kept in contact with the tappet 10 for a long time, and the period during which the cam surface is in contact with the tappet 10 is short. Therefore, 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.
[0027]
Conversely, assuming that the eccentric cam portion 18 is positioned downward in the figure, the rocker arm 6 is positioned downward as a whole, and the end of the swing cam 9 on the side of the connecting pin 17 is relatively pushed downward. It becomes a state. That is, the initial position of the swing cam 9 is inclined in a direction in which the cam surface approaches the tappet 10. Therefore, when the swing cam 9 swings as the drive shaft 2 rotates, the portion that contacts the tappet 10 immediately shifts from the base circle surface to the cam surface. Therefore, the lift amount is increased as a whole, and the operating angle is increased.
[0028]
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 operating angle can be continuously expanded and contracted simultaneously. Depending on the layout of each part, for example, the opening timing and closing timing of the intake valve 11 change substantially symmetrically as the lift and operating angle change. FIG. 3 shows the relationship between the rotation angle of the control shaft 12 (abbreviated as C / SFT in the drawing) and the lift / operation angle.
[0029]
Next, as shown in FIG. 1, the phase variable mechanism 21 relatively connects the 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 to be rotated. The sprocket 22 is interlocked with the crankshaft via a timing chain or a timing belt (not shown). The phase control actuator 23 is composed of, for example, a hydraulic or electromagnetic rotary actuator, and is controlled by a control signal from the engine control unit 19. The action of the phase control actuator 23 causes the sprocket 22 and the drive shaft 2 to rotate relative to each other, thereby delaying the lift center angle in the valve lift. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The actual control state of the phase variable mechanism 21 is detected by the drive shaft sensor 16 that responds to the rotational position of the drive shaft 2, and based on this, the actuator 23 is closed-loop controlled.
[0030]
In the internal combustion engine of the present embodiment provided with such a variable valve device on the intake valve side, the intake amount is controlled by variable control of the intake valve 11 without depending on the throttle valve. In a practical engine, it is preferable that a slight negative pressure exists in the intake system due to recirculation of blow-by gas, etc. Therefore, as described later, instead of a throttle valve, a negative pressure is provided upstream of the intake passage. It is desirable to provide an appropriate throttle mechanism for generating pressure.
[0031]
The intake air amount control using the lift / operating angle variable mechanism 1 and the phase variable mechanism 21 will be described. FIG. 4 shows the valve lift characteristics of the intake valve under typical operating conditions. As described above, in an extremely low load region such as an idle, the lift amount is a minimum lift. In particular, the lift amount is so small that the phase of the lift center angle does not affect the intake air amount. The phase of the lift center angle by the phase variable mechanism 21 is the most retarded position, so that the closing timing is the position immediately before the bottom dead center.
[0032]
By setting the minimum lift in this way, the intake flow becomes choked in the gap between the intake valves 11, and the necessary minute flow rate can be stably obtained in the extremely low load region. Since the closing time is near the bottom dead center, the effective compression ratio is sufficiently high, and it is possible to ensure relatively good combustion in combination with the improvement of gas flow by the minimal lift.
[0033]
On the other hand, in the low load region where the load is higher than the extremely low load region such as idle (including the idle state where the auxiliary load is applied), the lift / operating angle is large and the lift center angle is the advanced position. It becomes. At this time, the intake air amount control is performed in consideration of the valve timing, and the intake air amount is controlled to a relatively small amount by advancing the intake valve closing timing. As a result, the lift / operating angle becomes somewhat large, and the pumping loss due to the intake valve 11 is reduced.
[0034]
Note that in the case of a minimal lift in an extremely low load range such as idle, the intake air amount hardly changes even if the phase is changed, as described above, so when shifting from the very low load range to the low load range, Prior to the change, it is necessary to enlarge the lift and operating angle. The same applies when a load of auxiliary equipment such as an air conditioning compressor is applied.
[0035]
On the other hand, in the middle load region where the load is further increased and the combustion is stabilized, as shown in FIG. 4, the phase of the lift center angle is advanced while further increasing the lift / operation angle. The phase of the lift center angle is the most advanced state at a certain point in the middle load region. Thereby, internal EGR is utilized and the pumping loss can be further reduced.
[0036]
In addition, at the maximum load, the phase variable mechanism 21 is controlled so that the lift / operation angle is further expanded and the optimum valve timing is obtained. As shown in the figure, the optimum valve lift characteristic varies depending on the engine speed.
[0037]
5 and 6 show the configuration of the fuel supply system of the internal combustion engine. An electromagnetic fuel injection valve 52 is disposed upstream of the intake port 51 opened and closed by the intake valve 11, and the intake valve The fuel is injected to 11. In addition, 53 is the negative pressure adjusting valve for generating negative pressure described above provided in the intake passage 55 on the upstream side, 54 is an air cleaner, 56 is an exhaust passage, 57 is a catalytic converter, and 58 is a spark plug. As shown in FIG. 6, the fuel injection valve 52 forms a pair of conical sprays F corresponding to the pair of intake valves 11, and the outer peripheral portion of each spray F is the intake valve 11. The spread of the spray is set so as to overlap the seal portion on the outer periphery of the umbrella portion.
[0038]
Next, the fuel injection timing by the fuel injection valve 52 will be described.
[0039]
When the lift amount of the intake valve 11 is reduced 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 fuel is supplied at that time, the fuel can be atomized by the increased air flow velocity. Therefore, when the intake valve 11 is extremely low lifted, the intake stroke injection can be used relatively easily without depending on the secondary atomization by the waiting time injection, and the injection timing is set according to the lift amount. It is possible to switch to the waiting time injection. Also, when waiting time injection is performed during extremely low lift, fuel droplets adhere to the vicinity of the valve seat, fuel is supplied into the cylinder before the flow velocity develops, and the initial fuel particle size increases. Due to cycle variations in the degree of adhesion of fuel droplets, the flow passage area in the intake valve 11 may change, causing variations in the amount of supplied air. Therefore, in the present invention , basically , the intake stroke injection and the waiting time injection are set by the lift amount of the intake valve 11 as shown in FIG. That is, the intake stroke injection is set below the predetermined lift amount, and the waiting time injection is set above the predetermined lift amount. The lift amount is determined based on the rotation angle of the control shaft 12.
[0040]
FIG. 8 is a flowchart of a reference example for controlling the injection timing based on the rotation angle of the control shaft 12. The process flow will be described below according to this flowchart.
[0041]
First, in step 101, the rotation angle of the control shaft 12 (abbreviated as C / SFT in the figure) is read. In step 102, it is determined whether the rotation angle is equal to or less than a predetermined rotation angle X corresponding to a predetermined lift amount. If it is equal to or smaller than the rotation angle X, the routine proceeds to step 103 and intake stroke injection is performed. In the next step 104, the advance 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 shaft angle and the phase control amount. In the following step 105, in order to ensure the intake stroke injection, the fuel injection start timing is obtained as the intake valve opening start timing calculated in the general step 104, and the fuel is supplied to the intake port only during the fuel injection period corresponding to the air amount. Inject into.
[0042]
On the other hand, if it is determined in step 102 that the rotation angle is larger than the predetermined rotation angle X, the process proceeds to step 106, and the waiting time injection is performed. In the next 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 shaft angle and the phase control amount. In the following step 108, in order to ensure the waiting time injection, the fuel injection end timing is set before the intake valve opening start timing calculated in step 107, and the required fuel injection period according to the air amount is traced back. The fuel injection is executed with the injection timing as the injection start timing.
[0043]
FIG. 9 is a timing chart showing the intake stroke injection and the waiting time injection in comparison.
[0044]
Thus, by using the intake stroke injection to the intake valve low lift, the fuel atomization effect due to the high intake flow velocity in the vicinity of the seal portion of the intake valve 11 can be effectively used, and the unburned fuel can be reduced and the intake air can be reduced. Fuel adhering to the port 51 is suppressed, fuel arrival delay at the time of transition can be reduced, and cycle variation with respect to the set air-fuel ratio can be reduced, and exhaust performance and operability can be improved. In addition, fuel adhesion is further suppressed by making the conical fuel spray correspond to the outer diameter of the intake valve 11. In addition, when the intake valve is in a high lift where the flow velocity near the seal portion is low, by using 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. Can do.
[0045]
Next, a first embodiment of the present invention corresponding to claim 1 will be described with reference to FIGS.
[0046]
In this embodiment, in addition to the reference example , the fuel injection timing is switched in consideration of the engine rotational speed. As shown in FIG. 10, the intake valve lift amount and the engine speed are changed. With the speed as a parameter, intake stroke injection and waiting time injection are selectively set. That is, basically, intake stroke injection is performed below a predetermined lift amount, and waiting time injection is performed above a predetermined lift amount, but as the rotational speed increases, the value of the predetermined lift amount serving as a switching point increases.
[0047]
This is because the differential pressure across the intake valve 11 increases due to the increase in piston speed and the air flow rate increases as a result of an increase in the piston speed even with the same lift amount. is there. In other words, as the engine speed increases, the valve lift amount at which the air flow rate becomes the same can be increased. In the region where the flow in the gap between the intake valve 11 and the valve seat is already choked, the flow velocity of the flow in this portion does not change, but the flow velocity in the cylinder increases due to a decrease in cylinder density. After all, atomization can be achieved.
[0048]
Referring to the flowchart of FIG. 11, in step 111, the rotation angle of the control shaft 12 (C / SFT) and the engine rotational speed are read, and in step 112, a determination map indicating a region where the intake stroke injection is to be performed is referred to. . This map is set to the characteristics shown in FIG. In step 113, it is determined based on this map whether the region is the region where the intake stroke injection is performed. If it is the region that should be the intake stroke injection, the routine proceeds to step 114 where the intake stroke injection is set. 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 shaft angle and the phase control amount. In the following step 116, in order to ensure the intake stroke injection, the fuel injection start timing is obtained as the intake valve opening start timing calculated in the general step 115, and the fuel is supplied to the intake port only during the fuel injection period corresponding to the air amount. Inject into.
[0049]
On the other hand, if it is determined in step 113 that the region is not to be the intake stroke injection, the routine proceeds to step 117 and the waiting time injection is performed. In the next 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 shaft angle and the phase control amount. In the following step 119, in order to ensure the waiting time injection, the fuel injection end timing is set before the intake valve opening start timing calculated in step 118, and the required fuel injection period according to the air amount is traced back. The fuel injection is executed with the injection timing as the injection start timing.
[0050]
Therefore, as shown in FIG. 10, the limit lift amount that can perform the intake stroke injection increases with the increase of the rotational speed, and the operation region in which the atomization effect by the high flow velocity can be obtained increases.
[0051]
Next, a second embodiment corresponding to claim 2 will be described with reference to FIGS.
[0052]
In this embodiment, the fuel injection timing is set in consideration of the advance amount of the intake valve lift center angle by the phase variable mechanism 21 in addition to the intake valve lift amount. That is, as shown in FIG. 12, basically, the intake stroke injection is performed below the predetermined lift amount, the waiting time injection is performed above the predetermined lift amount, and further, in the case of the intake stroke injection, the phase control amount and From the lift amount, it is selected whether the injection start timing is the approximate intake valve opening start timing or the intake top dead center of the piston. As shown in the drawing, in the region where the intake valve lift central angle is greatly advanced, the injection start timing is set to the approximate intake top dead center.
[0053]
This is because when the intake valve 11 is opened during the exhaust stroke, the burned gas is blown back from the inside of the cylinder to the intake port 51, and at that time, when the fuel is injected toward the intake valve 11, it is blown back. This is because the fuel spray may be blown back together with the gas. When the fuel is blown back, the fuel is likely to adhere to the inner wall surface of the port, cycle variations, etc., as in the case of the waiting time injection. Therefore, in the present embodiment, the valve overlap is obtained 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.
[0054]
Referring to the flowchart of FIG. 13, first, at step 131, the rotation angle of the control shaft 12 (C / SFT) is read together with the phase control amount of the phase variable mechanism 21, and at step 132 whether the rotation angle is equal to or less than the predetermined rotation angle X. to decide. When the rotation angle is equal to or smaller than the predetermined rotation angle X, the process proceeds to step 133, and the intake stroke injection is performed.
[0055]
In subsequent step 134, the injection start timing correction map is referred to. In addition, the intake valve opening timing and the valve opening period are calculated from the control shaft 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 characteristics as shown in FIG. If 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. If it is determined in step 135 that the fuel injection start timing needs to be corrected, the routine proceeds to step 136, where the injection is executed with the fuel injection start timing as the intake top dead center of each cylinder.
[0056]
On the other hand, if it is determined in step 132 that the rotation angle is equal to or greater than the predetermined rotation angle X, the process proceeds to step 138, and the waiting time injection is performed. Calculate the valve period. In the following step 139, in order to ensure the waiting time injection, the fuel injection end timing is set before the intake valve opening start timing calculated in step 138, and the required fuel injection period according to the air amount is traced back. The fuel injection is executed with the injection timing as the injection start timing.
[0057]
Therefore, as shown in FIG. 12, when the lift amount is equal to or less than a predetermined lift amount, intake stroke injection is performed, and when blowback gas is generated due to valve overlap, fuel injection is started from the intake top dead center. It is possible to avoid spray blowback in the stroke injection. Note that the heat of the blown-back gas can be utilized for fuel atomization while avoiding the blowback of the spray.
[0058]
Next, a third embodiment disclosing the contents of claim 3 will be described with reference to FIGS. The third embodiment is based on the second embodiment and changes the limit lift amount for performing the intake stroke injection in accordance with the phase control amount of the phase variable mechanism 21.
[0059]
If the valve overlap is negative, the cylinder expands adiabatically during the intake stroke and the pressure drops. As described above, since the operating angle becomes small at the same time when the lift is low, if 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 intake valve lift becomes large. Therefore, as shown in FIG. 14, the lift amount that can be used for intake stroke injection is retarded. Can be set higher on the side.
[0060]
Further, the valve overlap is positive in a region where the phase variable mechanism 21 is advanced to some extent, but when there is such a valve overlap, if the phase of the intake valve lift is further advanced, the burned combustion that becomes the internal EGR As the amount of gas increases, the heat supplied to the intake air increases. Therefore, as shown in FIG. 14, the fuel vaporization is promoted toward the advance side, and the lift amount that can be injected in the intake stroke can be set higher.
[0061]
The outline of the processing flow of the present embodiment will be described with reference to the flowchart of FIG. 15. In step 151, the rotation angle of the control shaft 12 and the phase control amount of the phase variable mechanism 21 are read. A predetermined map for determining the fuel injection timing is referred to from the 12 rotation angles and the phase control amount. This map is created in advance basically according to the characteristics shown in FIG. In the subsequent step 153, the fuel injection timing is determined based on the referenced map, and the injection is executed. Note that, in the case of the waiting time injection, the injection start timing is obtained from the injection end timing, as in the above-described embodiments. 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 the intake stroke injection is given as high as possible.
[0062]
In addition, it is desirable that the injection start timing in the present invention takes into account the invalid pulse width generated when the injection valve is driven. In addition, since the fuel spray intake valve arrival timing is the most important, it is more desirable to set the fuel injection start timing in consideration of the arrival time from when the spray reaches the intake valve to the intake valve.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the overall configuration of a variable valve operating apparatus used in an internal combustion engine of the present invention.
FIG. 2 is a lift characteristic diagram showing a state of change in lift and operating angle.
FIG. 3 is a characteristic diagram showing a relationship between a rotation angle of a control shaft and a lift / operation 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 characteristics of switching between intake stroke injection and waiting time injection with respect to a lift amount in a reference example .
FIG. 8 is a flowchart showing the flow of processing in a reference example .
FIG. 9 is a time chart showing the intake stroke injection and the waiting time injection in comparison.
FIG. 10 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the first embodiment.
FIG. 11 is a flowchart showing the flow of processing in the first embodiment.
FIG. 12 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the second embodiment.
FIG. 13 is a flowchart showing the flow of processing in the second embodiment.
FIG. 14 is a characteristic diagram showing characteristics of switching between intake stroke injection and waiting time injection in the third embodiment.
FIG. 15 is a flowchart showing the flow of processing in the third embodiment.
[Explanation of symbols]
DESCRIPTION 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 shaft 14 ... Control shaft sensor 16 ... Drive shaft sensor 19 ... Engine control Unit 21 ... Phase variable mechanism 52 ... Fuel injection valve

Claims (5)

A variable valve mechanism that can change the lift amount of the intake valve;
A fuel injection valve that injects fuel into the intake passage;
According to the control state of the variable valve mechanism, a first injection timing for terminating the fuel injection before the intake valve opens and a second injection timing for performing the fuel injection during the valve opening period of the intake valve , A control device for selecting the first injection timing when the lift amount of the intake valve is larger than a predetermined lift amount , and for selecting the second injection timing when the lift amount of the intake valve is smaller than the predetermined lift amount ;
Equipped with a,
An internal combustion engine with a variable valve mechanism , characterized in that the value of the predetermined lift amount increases as the rotational speed of the internal combustion engine increases . A variable valve mechanism that can change the lift amount of the intake valve;
A fuel injection valve that injects fuel into the intake passage;
According to the control state of the variable valve mechanism, a first injection timing for terminating the fuel injection before the intake valve opens and a second injection timing for performing the fuel injection during the valve opening period of the intake valve, A control device for selecting the first injection timing when the lift amount of the intake valve is larger than a predetermined lift amount, and for selecting the second injection timing when the lift amount of the intake valve is smaller than the predetermined lift amount;
A second variable valve mechanism that can change the phase of the lift center angle of the intake valve ;
With
During the second injection timing selected, controllable state of the second variable valve mechanism you characterized in that the intake top dead center after the start of fuel injection when in the advance side of a predetermined phase Internal combustion engine with variable valve mechanism. 3. The internal combustion engine with a variable valve mechanism according to claim 2 , wherein the value of the predetermined lift amount increases with advance of the control state of the second variable valve mechanism. The variable valve mechanism includes an eccentric cam that is rotationally driven by a drive shaft, a link arm that is fitted to the outer periphery of the eccentric cam so as to be relatively rotatable, and an eccentric cam portion that is provided in parallel to the drive shaft. Further, a control shaft that is rotatable within at least a predetermined angle range, a rocker arm that is rotatably attached to an eccentric cam portion of the control shaft, and is pivoted by the link arm, and is rotatably supported by the drive shaft. And a rocking cam that is connected to the rocker arm via a link and rocks with the rocker arm to press the intake valve, and a lift / operating angle control actuator that changes the rotational position of the control shaft, The lift of the intake valve varies with the operating angle according to the rotational position of the eccentric cam portion of the control shaft. Variable valve mechanism with an internal combustion engine according to any one of 1-3. The fuel injection valve has a conical spray form according to any one of claims 1 to 4, the outer peripheral portion of the spray is characterized by being configured to overlap the sealing portion of the intake valve periphery An internal combustion engine with a variable valve mechanism.

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