JP2011140962A - Fuel injection control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inject fuel necessary for forming an air-fuel mixture of a target air-fuel ratio in response to operation of a variable valve system after determination of a fuel injection amount in an engine including a cylinder direct injection type fuel injection valve directly injecting fuel into a cylinder, and a variable valve gear varying an opening characteristic of an intake valve. <P>SOLUTION: First fuel injection of injecting a first injection amount, and second fuel injection of injecting a second injection amount by the cylinder direct injection type fuel injection valve at a vicinity of valve closing timing of the intake valve are carried out. At this time, computing timing of the second injection amount is set on the basis of closing timing of the intake valve based upon a controlled variable of the variable valve gear in computing timing of the first injection amount, and the second injection amount is set on the basis of a change rate of the closing timing of the intake valve based upon a controlled variable of the variable valve gear in the computing timing of the second injection amount with respect to the closing timing, and a deviation between an intake air amount based upon the controlled variable of the variable valve gear in the computing timing of the first injection amount, and an intake air amount based upon the controlled variable of the variable valve gear in the computing timing of the second injection amount. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an engine fuel injection control device that includes an in-cylinder direct injection type fuel injection valve that directly injects fuel into a cylinder and a variable valve mechanism that varies the opening characteristics of an intake valve.

  Patent Document 1 discloses an intake valve injection valve that injects fuel into an intake passage upstream of an intake valve, an in-cylinder injection valve that directly injects fuel into a cylinder, a lift amount of the intake valve and / or a valve. In an engine equipped with a variable valve mechanism that changes timing, the intake passage relative to the total fuel injection amount becomes smaller as the lift amount of the intake valve becomes smaller and / or the opening timing of the intake valve becomes later after the intake top dead center. A control system is disclosed in which the ratio of the fuel injection amount from the inner injection valve is lowered and the ratio of the fuel injection amount from the in-cylinder injection valve to the total fuel injection amount is increased.

JP 2005-248883 A

  By the way, when the cylinder intake air amount is controlled by continuously changing the opening characteristic of the intake valve by the variable valve mechanism, even during the transient operation in which the opening characteristic of the intake valve is changing, even after the intake valve starts to open. Since the opening characteristic (valve lift amount) of the intake valve gradually changes, the cylinder intake air amount in the intake stroke is determined when the intake valve is closed.

However, in order to increase the homogeneity of the air-fuel mixture, it is required to inject fuel at an early stage. For this reason, the injection timing in the case of performing homogeneous combustion is, for example, exhaust when injecting into the intake port. It was set from the stroke (before the intake valve was opened) to the first half of the intake stroke (immediately after the intake valve was opened), and in the case of direct injection into the cylinder, it was set immediately after the exhaust valve was closed.
For this reason, there is a large difference between the timing at which the cylinder intake air amount is finally determined and the timing at which the fuel injection amount is determined, and after the fuel injection amount is determined, the variable valve mechanism operates to open the intake valve opening characteristics. When the change occurs, a difference occurs between the cylinder intake air amount adapted to the fuel injection amount and the actual cylinder intake air amount, and the actual air-fuel ratio deviates from the target air-fuel ratio.

In other words, since the intake air amount changes due to the operation of the variable valve mechanism, when the variable valve mechanism operates after the fuel injection amount is determined, the amount of change in the intake air amount due to the operation exceeds the fuel injection amount. There will be a shortage.
When the actual air-fuel ratio deviates from the target air-fuel ratio during the transient operation of the engine, there has been a problem that exhaust properties deteriorate or power performance deteriorates.

  The present invention has been made in view of the above problems, and includes a direct injection type fuel injection valve that directly injects fuel into a cylinder, and a variable valve mechanism that varies the opening characteristics of the intake valve. It is an object of the present invention to allow fuel required for formation of an air-fuel mixture with a target air-fuel ratio to be injected in accordance with the operation of the variable valve mechanism after the injection amount is determined.

Therefore, an engine fuel injection control device according to the present invention includes a direct injection type fuel injection valve that directly injects fuel into a cylinder, and a variable valve mechanism that varies the opening characteristics of the intake valve. In the engine
A first injection for injecting a first injection amount, and a second injection for injecting a second injection amount by the direct injection type fuel injection valve after the first injection and in the vicinity of the closing timing of the intake valve And
A fuel injection control device that corrects the second injection amount based on a change in an intake air amount generated by an operation of the variable valve mechanism after the calculation of the first injection amount;
The calculation timing of the second injection amount is set based on the closing timing of the intake valve based on the control amount of the variable valve mechanism at the calculation timing of the first injection amount,
The rate of change of the closing timing of the intake valve based on the control amount of the variable valve mechanism at the calculation timing of the second injection amount with respect to the closing timing, and the variable valve mechanism at the calculation timing of the first injection amount The second injection amount is set based on a deviation between the intake air amount based on the control amount and the intake air amount based on the control amount of the variable valve mechanism at the calculation timing of the second injection amount.

  According to the above invention, the second injection amount in the second injection performed near the closing timing of the intake valve can be changed in response to the change in the intake air amount after the calculation of the first injection amount in the first injection. The amount of fuel that can be obtained and corresponds to the cylinder intake air amount in the intake stroke determined when the intake valve is closed, and the sum of the first injection amount and the second injection amount is obtained. It can be.

The block diagram of an engine provided with a port injection type fuel injection valve and a cylinder direct injection type fuel injection valve in embodiment of this invention. The block diagram of an engine provided only with an in-cylinder direct injection type fuel injection valve in the embodiment of the present invention. Sectional drawing (AA sectional drawing of FIG. 4) of the variable valve lift mechanism VEL in embodiment of this invention. The side view of the said variable valve lift mechanism VEL. The top view of the said variable valve lift mechanism VEL. The perspective view which shows the eccentric cam used for the said variable valve lift mechanism VEL. Sectional drawing which shows the effect | action at the time of the low lift of the said variable valve lift mechanism VEL (BB sectional drawing of FIG. 4). Sectional drawing which shows the effect | action at the time of the high lift of the said variable valve lift mechanism VEL (BB sectional drawing of FIG. 4). FIG. 6 is a valve lift characteristic diagram corresponding to the base end surface of the swing cam and the cam surface in the variable valve lift mechanism VEL. The valve timing of the said variable valve lift mechanism VEL and the characteristic figure of a valve lift. The perspective view which shows the rotational drive mechanism of the control shaft in the said variable valve lift mechanism VEL. Sectional drawing of the variable valve timing mechanism (VTC) 114 in embodiment of this invention. The block diagram which shows the whole structure of the intake air amount (torque) control in embodiment of this invention. The block diagram which shows the calculation of the target operating angle of the variable valve lift mechanism VEL in embodiment of this invention. The block diagram which shows the setting of the valve timing correction value KHOSIVC which correct | amends a VEL target operating angle according to the valve closing timing of an intake valve in embodiment of this invention. The figure which shows the setting of the valve | bulb upstream pressure correction value KMANIP which correct | amends a VEL target operating angle according to the intake pressure of the intake valve upstream in this embodiment of this invention. The block diagram which shows the target throttle opening calculation in embodiment of this invention. The block diagram which shows the setting of the intake valve opening correction value KAVEL in embodiment of this invention. The block diagram which shows calculation of the intake valve passage volume flow ratio WQH0VEL and the actual intake valve passage volume flow ratio RQH0VEL when the throttle valve is fully opened in the embodiment of the present invention. The figure which shows the correlation with the timing of the 1st, 2nd injection in the engine provided with the port injection type fuel injection valve of embodiment of this invention, and the lift state of an intake / exhaust valve. The figure which shows the correlation with the timing of the 1st, 2nd injection in the engine provided only with the cylinder direct injection type fuel injection valve of embodiment of this invention, and the lift state of an intake / exhaust valve. The flowchart which shows the calculation of the 1st injection quantity Ti in the 1st injection performed by the exhaust stroke in the embodiment of the present invention. The block diagram which shows the calculation of the start timing of the 2nd injection in embodiment of this invention. The flowchart which shows the calculation of the port wall flow correction amount in embodiment of this invention. The diagram which shows the correlation of the balance wall flow adhesion amount, engine load TP, and engine speed NE in the intake port in embodiment of this invention. The diagram which shows the correlation with the water temperature coefficient and water temperature TW which correct | amend the cylinder inner wall flow correction | amendment basic value in embodiment of this invention. The diagram which shows the correlation with the (DELTA) TVO coefficient which correct | amends the cylinder inner wall flow correction | amendment basic value in embodiment of this invention, and change (DELTA) TVO of the throttle valve opening degree TVO. The flowchart which shows the calculation of the cylinder inner wall flow correction amount in embodiment of this invention. The diagram which shows the correlation with the balance wall flow adhesion amount in the cylinder in the embodiment of this invention, engine load TP, and engine speed NE. The diagram which shows the correlation with the time coefficient after starting which correct | amends the cylinder wall flow correction | amendment basic value in embodiment of this invention, and the elapsed time after starting. The diagram which shows the correlation with the intake stroke injection basic share amount Tveldef, engine load TP, and engine rotational speed NE in embodiment of this invention. The flowchart which shows the calculation of the 2nd injection quantity Tint in the 2nd injection performed by the intake stroke in embodiment of this invention. The diagram which shows the correlation with the correction coefficient HOSEI and water temperature TW which correct | amend correction part Tintbas in embodiment of this invention. The figure which shows the characteristic of the injection quantity at the time of acceleration (at the time of the increase change of a valve lift amount) in embodiment of this invention. The figure which shows the characteristic of the injection quantity at the time of the deceleration in the embodiment of this invention (at the time of the decrease change of valve lift amount).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vehicle engine to which a fuel injection control device according to the present invention is applied.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of an engine 101. Air is drawn through the control throttle 104 and the intake valve 105.

The intake port 102 upstream of the intake valve 105 is provided with a port injection fuel injection valve 121 for each cylinder. The port injection fuel injection valve 121 injects fuel into the intake port 102.
Further, an in-cylinder direct injection type fuel injection valve 122 for directly injecting fuel into the cylinder is provided for each cylinder.

Both the fuel injection valves 121 and 122 are opened by the magnetic attractive force of the electromagnetic coil and inject fuel in an amount proportional to the valve opening time (injection pulse width).
The fuel in the combustion chamber 106 is ignited and burned by spark ignition by a spark plug (not shown).
The combustion exhaust in the combustion chamber 106 is discharged to the exhaust pipe 123 through the exhaust valve 107.

Exhaust gas led out from the combustion chamber 106 by the exhaust pipe 123 passes through the catalytic converter 108 and the muffler 109 and is then released into the atmosphere.
The exhaust valve 107 is opened and closed by a cam 111 provided integrally with the exhaust camshaft 110 while maintaining a constant valve lift, valve operating angle, and valve timing.
On the other hand, the intake valve 105 is configured such that a valve lift amount and a valve operating angle are continuously changed by a variable valve lift mechanism (VEL) 112 as a variable valve mechanism.

Further, at the end of the intake camshaft 113, a variable valve timing mechanism (continuously changing the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft 113 with respect to the crankshaft 124). VTC) 114 is provided.
The electronic control throttle 104, the fuel injection valves 121 and 122, the variable valve lift mechanism (VEL) 112, and the variable valve timing mechanism (VTC) 114 are controlled by a control unit (C / U) 115 incorporating a microcomputer.

Signals from various sensors are input to the control unit (C / U) 115.
The various sensors include an accelerator opening sensor 116 that detects an accelerator pedal depression amount (accelerator opening) ACC, an air flow meter (AF / M) 117 that detects an intake air amount Qa of the engine 101, and a rotation of the crankshaft 124. A crank angle sensor 118 that outputs an angle signal POS, a cam angle sensor 119 that outputs a rotation angle signal CAM of the intake camshaft 113, a throttle sensor 120 that detects an opening TVO of the throttle valve 103b, and the like are provided.

  The control unit (C / U) 115 detects the rotational phase of the intake camshaft 113 with respect to the crankshaft 124 based on the detection signals of the crank angle sensor 118 and the cam angle sensor 119, and sets the operating state of the engine 101. Accordingly, a target value (target advance value) of the rotational phase is set, and the variable valve timing mechanism (VTC) 114 is controlled so that the rotational phase of the intake camshaft 113 becomes the target value.

The control unit (C / U) 115 controls the electronic control throttle 104 and the variable valve lift mechanism (VEL) 112 so as to obtain an intake air amount corresponding to the accelerator opening ACC.
Specifically, the target intake pipe negative pressure (manifold negative pressure) is generated while controlling the intake air amount by controlling the valve lift amount and the valve operating angle by the variable valve lift mechanism (VEL) 112. In addition, the opening degree of the throttle valve 103b is controlled.

The intake pipe negative pressure is used for purging fuel vapor from a canister that collects fuel vapor generated in a fuel tank, processing blowby gas, and the like, as well as a power source in a master back that boosts brake operating force. Used as.
Note that, under an operating condition in which there is no demand for generation of intake pipe negative pressure, the throttle valve 103b is held fully open and the intake air amount is controlled only by the variable valve lift mechanism (VEL) 112.

In a low load region where the intake air amount cannot be controlled with the variable valve lift mechanism (VEL) 112 alone, the variable valve lift mechanism (VEL) 112 is controlled and the opening of the throttle valve 103b is throttled. I do.
In the vehicle engine shown in FIG. 1, each cylinder is provided with a port injection fuel injection valve 121 and an in-cylinder direct injection fuel injection valve 122. However, as shown in FIG. A vehicle engine in which only the in-cylinder direct injection fuel injection valve 122 is provided in each cylinder without including the injection valve 121 may be used.

The vehicle engine shown in FIG. 2 differs from the vehicle engine shown in FIG. 1 only in that the port injection type fuel injection valve 121 is omitted, and all other configurations are shown in FIG. Since it is the same as the vehicle engine, detailed description is omitted.
Next, the structure of the variable valve lift mechanism (VEL) 112 will be described.
As shown in FIGS. 3 to 5, the variable valve lift mechanism (VEL) 112 includes a hollow cam shaft 13 that is rotatably supported by the cam bearing 14 of the cylinder head 11 and a position above the cam shaft 13. A control shaft 16 rotatably supported by the same cam bearing 14 is provided as a common part for each cylinder, and is supported by a pair of intake valves 105 and 105 and the cam shaft 13 as a part for each cylinder. Two eccentric cams 15 and 15 that are rotating cams, a pair of rocker arms 18 and 18 that are swingably supported by the control shaft 16 via a control cam 17, and upper ends of intake valves 105 and 105, respectively. And a pair of independent rocking cams 20, 20 arranged via valve lifters 19, 19.

The eccentric cams 15 and 15 and the rocker arms 18 and 18 are linked by link arms 25 and 25, and the rocker arms 18 and 18 and the swing cams 20 and 20 are linked by link members 26 and 26.
As shown in FIG. 6, the eccentric cam 15 has a substantially ring shape, and includes a small-diameter cam main body 15a and a flange portion 15b integrally provided on the outer end surface of the cam main body 15a. A cam shaft insertion hole 15c is formed in a direction so as to penetrate in the direction, and the axis X of the cam body 15a is eccentric from the axis Y of the cam shaft 13 by a predetermined amount.

The eccentric cam 15 is press-fitted and fixed to the camshaft 13 on both outer sides that do not interfere with the valve lifter 19 via camshaft insertion holes 15c, and the outer peripheral surface 15d of the cam body 15a has the same cam profile. Is formed.
As shown in FIG. 5, the rocker arm 18 is bent in a substantially crank shape, and a central base 18 a is rotatably supported by the control cam 17.

In addition, a pin hole 18d into which a pin 21 connected to the distal end portion of the link arm 25 is press-fitted is formed at one end portion 18b protruding from the outer end portion of the base portion 18a of the rocker arm 18. A pin hole 18e into which a pin 28 connected to one end portion 26a (described later) of each link member 26 is press-fitted is formed in the other end portion 18c projecting from the inner end portion of 18a.
The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the shaft center P1 is eccentric from the shaft center P2 of the control shaft 16 by a predetermined amount α as shown in FIG.

As shown in FIGS. 3, 7, and 8, the rocking cam 20 has a substantially horizontal U shape, and a cam shaft 13 is fitted into a substantially annular base end portion 22 so as to be rotatably supported. A support hole 22a is formed in a penetrating manner, and a pin hole 23a is formed in the end 23 located on the other end 18c side of the rocker arm 18.
Further, a base circle surface 24a on the base end portion 22 side and a cam surface 24b extending in an arc shape from the base circle surface 24a to the end portion 23 edge side are formed on the lower surface of the rocking cam 20. The base circle surface 24 a and the cam surface 24 b are in contact with predetermined positions on the upper surface of each valve lifter 19 according to the swing position of the swing cam 20.

That is, when viewed from the valve lift characteristics shown in FIG. 9, as shown in FIG. 3, the predetermined angular range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angular range from the base circle section θ1 of the cam surface 24b. θ2 is a so-called ramp section, and further, a predetermined angle range θ3 from the ramp section θ2 of the cam surface 24b is set to be a lift section.
The link arm 25 includes an annular base portion 25a and a projecting end 25b projecting at a predetermined position on the outer peripheral surface of the base portion 25a. At the center position of the base portion 25a, the cam body 15a of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of the pin 21 so as to be freely rotatable, and a pin hole 25d through which the pin 21 is rotatably inserted is formed in the protruding end 25b.

The link member 26 is formed in a straight line having a predetermined length, and circular end portions 26a and 26b are provided on the pin holes 18d and 18d of the other end portion 18c of the rocker arm 18 and the end portion 23 of the swing cam 20, respectively. Pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 press-fitted into 23a are rotatably inserted are formed.
In addition, snap rings 30, 31, and 32 that restrict the axial movement of the link arm 25 and the link member 26 are provided at one end of each pin 21, 28, and 29.

As shown in FIG. 11, the control shaft 16 is rotationally driven within a predetermined rotational angle range by an actuator 201 such as a DC servo motor provided at one end, and the angle of the control shaft 16 Is changed by the actuator 201, the valve lift amount and the valve operating angle of the intake valves 105, 105 are continuously changed (see FIG. 10).
That is, in FIG. 11, the rotation of the actuator (DC servo motor) 201 is transmitted to the threaded shaft 103 through the transmission member 202, and the axial position of the nut 204 through which the shaft 203 is passed is determined. Change.

The control shaft 16 is rotated by a pair of stay members 205 a and 205 b attached to the tip of the control shaft 16 and having one end fixed to the nut 204.
In the present embodiment, as shown in FIG. 11, the valve lift amount is reduced by moving the position of the nut 204 closer to the transmission member 202, and conversely, the position of the nut 204 is moved away from the transmission member 202. Increases the valve lift.

  Further, an operating angle sensor 206 for detecting the angle (VEL operating angle) of the control shaft 16 is provided at the tip of the control shaft 16, and the actual control shaft 16 detected by the operating angle sensor 206 is provided. The control unit (C / U) 115 feedback-controls the operation amount of the actuator (DC servo motor) 201 so that the angle approaches the target angle (target VEL operating angle).

When the control shaft 16 is driven to rotate in one direction, the control cam 17 has the shaft center P1 in a rotational position on the upper left side from the shaft center P2 of the control shaft 16 as shown in FIGS. The thick portion 17a is held away from the cam shaft 13 and moved upward.
For this reason, the entire rocker arm 18 moves upward with respect to the camshaft 13, whereby each rocking cam 20 is forcibly pulled up slightly by the end portion 23 via the link member 26. Rotate left.

  Therefore, as shown in FIGS. 7A and 7B, when the eccentric cam 15 rotates and pushes up the one end portion 18b of the rocker arm 18 via the link arm 25, the lift amount swings via the link member 26. The lift amount L1 is transmitted to the cam 20 and the valve lifter 19, but the lift amount L1 is relatively small as shown in FIG. 7B, and the valve lift angle is simultaneously reduced as shown in FIG. (The angle of the valve opening period) becomes smaller.

On the other hand, when the control shaft 16 is driven in the reverse direction, as shown in FIGS. 8A and 8B, the control shaft 16 rotates the control cam 17 clockwise from the position shown in FIG. The shaft center P1 (thick part 17a) is moved downward.
Therefore, the entire rocker arm 18 moves in the direction of the camshaft 13 (downward), and the other end 18c presses the upper end 23 of the swing cam 20 downward via the link member 26. The entire swing cam 20 is rotated clockwise by a predetermined amount.

Accordingly, the contact position of the lower surface of the swing cam 20 with respect to the upper surface of the valve lifter 19 is moved to the left position as shown in FIGS.
Therefore, when the eccentric cam 15 rotates as shown in FIG. 8 and the one end 18b of the rocker arm 18 is pushed up via the link arm 25, the lift amount L2 with respect to the valve lifter 19 is as shown in FIG. 8B. As shown in FIG. 10, the valve lift amount increases and at the same time the valve operating angle increases.

FIG. 12 shows the structure of the variable valve timing mechanism (VTC) 114.
The variable valve timing mechanism (VTC) 114 in this embodiment is a hydraulic vane type mechanism, and is a cam sprocket 51 (timing sprocket) that is rotationally driven by a crankshaft 124 via a timing chain, and an end of the intake camshaft 113. A rotating member 53 that is fixed to the camshaft and rotatably accommodated in the cam sprocket 51, a hydraulic circuit 54 that rotates the rotating member 53 relative to the cam sprocket 51, the cam sprocket 51, and the rotating member 53 And a lock mechanism 60 that selectively locks the relative rotational position of the two at a predetermined position.

The cam sprocket 51 includes a rotating part (not shown) having a tooth part meshed with a timing chain (or timing belt) on the outer periphery, and a housing that is disposed in front of the rotating part and rotatably accommodates the rotating member 53. 56, and a front cover and a rear cover (not shown) for closing the front and rear openings of the housing 56.
The housing 56 has a cylindrical shape in which both front and rear ends are formed, and the inner peripheral surface has a trapezoidal cross section, and each of the four partition walls 63 provided along the axial direction of the housing 56 is 90 °. Projected at intervals.

The rotating member 53 is fixed to the front end of the intake camshaft 113, and four vanes 78a, 78b, 78c, and 78d are provided on the outer peripheral surface of the annular base 77 at 90 ° intervals.
Each of the first to fourth vanes 78a to 78d has a substantially inverted trapezoidal cross section, and is disposed in a recess between the partition walls 63. The recesses are separated from each other in the rotational direction, and the vanes 78a to 78d. An advance side hydraulic chamber 82 and a retard side hydraulic chamber 83 are formed between both sides and both side surfaces of each partition wall 63.

The lock mechanism 60 is configured such that the lock pin 84 engages with an engagement hole (not shown) at the rotation position (reference operation state) on the maximum retard angle side of the rotation member 53.
The hydraulic circuit 54 includes two systems, a first hydraulic passage 91 that supplies and discharges hydraulic pressure to the advance side hydraulic chamber 82 and a second hydraulic passage 92 that supplies and discharges hydraulic pressure to the retard side hydraulic chamber 83. These hydraulic passages 91 and 92 are connected to a supply passage 93 and drain passages 94a and 94b through passage switching electromagnetic switching valves 95, respectively.

The supply passage 93 is provided with an engine-driven oil pump 97 that pumps the oil in the oil pan 96, while the downstream ends of the drain passages 94 a and 94 b communicate with the oil pan 96.
The first hydraulic passage 91 is connected to four branch passages 91 d that are formed substantially radially in the base 77 of the rotating member 53 and communicate with the advance-side hydraulic chambers 82. It is connected to four oil holes 92 d that open to the retard side hydraulic chamber 83.

The electromagnetic switching valve 95 is configured such that an internal spool valve body relatively switches and controls the hydraulic passages 91 and 92, the supply passage 93, and the drain passages 94a and 94b.
The control unit (C / U) 115 controls the energization amount to the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal that controls the on-time ratio.

For example, when a control signal (OFF signal) with a duty ratio of 0% is output to the electromagnetic actuator 99, the hydraulic oil pressure-fed from the oil pump 47 is supplied to the retard-side hydraulic chamber 83 through the second hydraulic passage 92. At the same time, the hydraulic oil in the advance side hydraulic chamber 82 is discharged from the first drain passage 94 a into the oil pan 96 through the first hydraulic passage 91.
Therefore, the internal pressure of the retard side hydraulic chamber 83 is high and the internal pressure of the advance side hydraulic chamber 82 is low, and the rotating member 53 rotates to the maximum retard side via the vanes 78a to 78b. The center phase of the operating angle of the intake valve 105 is retarded.

On the other hand, when a control signal (ON signal) with a duty ratio of 100% is output to the electromagnetic actuator 99, the hydraulic oil is supplied into the advance side hydraulic chamber 82 through the first hydraulic passage 91 and the retard side hydraulic pressure is supplied. The hydraulic oil in the chamber 83 is discharged to the oil pan 96 through the second hydraulic passage 92 and the second drain passage 94b, and the retard side hydraulic chamber 83 becomes low pressure.
For this reason, the rotating member 53 rotates to the maximum advance side via the vanes 78a to 78d, whereby the central phase of the operating angle of the intake valve 105 is advanced.

  Note that the variable valve timing mechanism (VTC) 114 is not limited to the hydraulic vane type mechanism shown in FIG. 12, and for example, is displaced into a spiral guide disclosed in Japanese Patent Application Laid-Open No. 2003-184516. A variable valve timing mechanism including a movable guide portion that can be guided and engaged; a motor-type variable valve timing mechanism that drives a camshaft by a motor disclosed in Japanese Patent Application Laid-Open No. 2008-025541; It may be an electromagnetic brake type variable valve timing mechanism composed of a combination of a helical spline and an electromagnetic brake disclosed in 2007-120339.

Next, intake air amount control by the control unit (C / U) 115 will be described.
FIG. 13 is a block diagram showing the basic configuration of the control function of the intake air amount by the control unit (C / U) 115. As shown in FIG. 13, the control unit (C / U) 115 has a target volume. It has functions as a flow rate calculation unit a, a VEL target operating angle calculation unit b, and a target throttle opening calculation unit c (see Japanese Patent Application Laid-Open No. 2003-184587).

First, calculation processing in the target volume flow ratio calculation unit a will be described.
The target volume flow ratio calculation unit a calculates a target volume flow ratio TQH0ST corresponding to the target torque.
Specifically, while calculating the required air amount Q0 corresponding to the accelerator opening ACC and the engine speed NE, or obtaining the target torque set based on the accelerator opening ACC and the engine speed NE, The required idle air amount QISC required to bring the engine rotational speed NE close to the target idle rotational speed NE is calculated.

The engine speed NE is calculated by the control unit (C / U) 115 based on a signal from the crank angle sensor 118.
Then, the idle required air amount QISC is added to the required air amount Q0 to calculate the total required air amount Q (Q = Q0 + QISC), and the total required air amount Q is calculated based on the engine speed Ne and the exhaust amount (cylinder). The target volume flow ratio TQH0ST is calculated by dividing by (total volume) VOL #.

Formula (1) ... TQH0ST = Q / (Ne.VOL #)
Next, calculation processing in the VEL target operating angle calculation unit b will be described.
The VEL target operating angle calculator b calculates a target valve opening area TVELAA based on the target volume flow ratio TQH0ST, and further sets a target VEL operating angle TGVEL based on the target valve opening area TVELAA.

FIG. 14 shows details of the calculation function of the VEL target operating angle calculation unit b.
In FIG. 14, in part A, the larger one is selected by comparing the target volume flow ratio TQH0ST and the minimum volume flow ratio QH0LMT, and the volume flow ratio TQH0VEL to be realized by the variable valve lift mechanism VEL112 is set.
The minimum volume flow ratio QH0LMT is the minimum volume flow ratio that can be realized by the variable valve lift mechanism (VEL) 112, that is, the volume flow ratio at the minimum valve lift amount. Based on the above, by searching a table TQH0LMT as shown in the figure, the higher the engine speed NE, the larger the value is calculated.

In part B, the volume flow rate ratio TQH0VEL is converted into a state quantity VACDNV corresponding to the valve opening area AV based on a table TVACDNV as shown in the figure.
Here, VACDNV = AV · Cd / N / V, where AV is a valve opening area, Cd is a loss factor, N is a rotation speed, and V is an exhaust amount.
Then, the required valve opening area TVELAA0 is calculated by multiplying the state quantity VACDNV obtained in the B part by the engine rotational speed NE in the C part and the exhaust amount VOL # in the D part.

That is, the required valve opening area TVELAA0 is TVELAA0 = Av · Cd.
In section E, the required valve opening area TVELAA0 is divided by a correction value KHOSIVC corresponding to the valve closing timing IVC of the intake valve 105 to calculate the required valve opening area TVELAA1.

This is because the effective cylinder volume decreases when the valve closing timing IVC of the intake valve 105 is advanced, and the volume flow rate ratio decreases even at the same valve opening area. TVELAA0 is corrected.
In the F part, the required valve opening area TVELAA1 calculated in the E part is multiplied by the correction value KMANIP set in accordance with the upstream intake pipe pressure to the intake valve 105 to obtain the required valve opening area TVELAA2.

In the G part, the required valve opening area TVELAA2 calculated in the F part is divided by the correction value KHOSNE set according to the engine speed NE to obtain the required valve opening area TVELAA.
The correction value KHOSNE is calculated by searching a table TKHOSNE as shown in the figure based on the engine speed Ne in the g1 part, and is set to a value larger than 1 as the engine speed NE increases.

In the part H, the required valve opening area TVELAA is converted into a target VEL operating angle TGVEL0 (target angle of the control shaft 16) using a table TTGVEL0 as shown in the figure.
In part I, the target VEL operating angle TGVEL0 obtained in part H is compared with the maximum VEL operating angle VELHLMT. If TGVEL0 ≧ VELHLMT, VELHLMT is set as the target VEL operating angle TGVEL, and If there is, TGVEL0 is set as the target VEL operating angle TGVEL.

The maximum VEL operating angle VELHLMT is calculated by searching a table TVELHLMT as shown in the figure based on the engine rotational speed Ne in the i1 part.
The control unit C / U 115 feedback-controls the operation amount of the actuator 201 so that the actual VEL operating angle VELCOM (the actual angle of the control shaft 16) becomes the target VEL operating angle TGVEL.

Here, the setting of the correction value KHOSIVC used in the E part of FIG. 14 will be described based on FIG.
In FIG. 15, in the e1 part, when the variable valve timing mechanism (VTC) 114 is not operating, that is, when the central phase of the operating angle of the intake valve 105 is the most retarded state, the intake valve 105 is closed. The angle V0IVC of the timing IVC is obtained with reference to a table TV0IVC as shown in the drawing based on the valve operating angle VSC-ANGL of the intake valve 105 at that time.

Next, in part e2, the actual IVC angle REALIVC is obtained by subtracting the advance value VTCNOW of the center phase at that time by the variable valve timing mechanism (VTC) 114 from the angle V0IVC of the valve closing timing IVC. .
Then, in section e3, based on the actual IVC angle REALIVC, a table TKHOSIVC as shown in the figure is searched to set a correction value KHOSIVC and output to section E in FIG.

Next, the setting of the correction value KMANIP used in the F part of FIG. 14 will be described based on FIG.
In the f1 part of FIG. 16, the correction value KMANIP is atmospheric pressure / target boost (for example, 101.3 KPa / 88 KPa) or 1.0, and the target volume flow rate TQH0ST is less than or equal to the minimum volume flow rate ratio QH0LMT. Then, 1.0 is output as the correction value KMANIP, and otherwise, the atmospheric pressure / target boost is output as the correction value KMANIP.

Next, calculation processing in the target throttle opening calculation unit c will be described with reference to FIG.
In FIG. 17, the J portion calculates a state quantity TADNV0 corresponding to the opening area At of the throttle valve required when the operation characteristic of the intake valve 105 is in the reference state.
The case where the operating characteristic is in the reference state corresponds to the case where the valve lift amount, the valve operating angle, and the valve timing of the intake valve 105 are fixed and the intake air amount of the engine 101 is controlled by the throttle valve opening.

The J section calculates TADNV0 by searching a conversion table TTADNV0 as shown in the figure based on the target volume flow ratio TQH0ST.
The state quantity TADNV0 is represented by TADNV0 = At / (Ne · VOL #), where At is the throttle valve opening area, Ne is the engine speed, and VOL # is the displacement (cylinder volume). It is.

Then, the calculated TADNV0 is multiplied by the engine rotational speed Ne in the K portion and the exhaust amount VOL # in the L portion, and the throttle required opening area TVOAA0 when the operation characteristic of the intake valve 105 is in the reference state is calculated.
In the M section, the calculated throttle required opening area TVOAA0 is corrected according to the actual operating characteristic of the intake valve 105, that is, the operating characteristic.

Specifically, the target throttle opening area TVOAA is calculated by multiplying the throttle required opening area TVOAA by a correction value KAVEL set according to the actual operating characteristic of the intake valve 105.
In the N section, based on the calculated target throttle opening area TVOAA, a conversion table TTDTVO as shown in the figure is searched to set the target throttle opening TDTVO.

The control unit (C / U) 115 feedback-controls the operation amount of the electronic control throttle 104 so that the actual opening degree TVO of the throttle valve 103b converges to the target throttle opening degree TDTVO.
Here, the setting of the correction value KAVEL used in the M part of FIG. 17 will be described with reference to FIG.

18, the pressure ratio Pm′0 / Pa is obtained with reference to a map as shown in the drawing based on the target volume flow rate ratio TQH0ST and the engine speed NE.
Note that Pa is the atmospheric pressure, and Pm′0 is the intake manifold pressure when the operation characteristic of the intake valve 105 is in the reference state.
Then, in the m2 part, based on the pressure ratio Pm′0 / Pa, the table TBLKPA0 shown in the figure is searched to calculate the coefficient KPA0.

On the other hand, in the m3 part, by multiplying the intake valve passage volume flow rate ratio WQH0VEL when the throttle valve 103b is fully opened by the conversion constant TPGAIN #, the amount of air TP100 taken into the cylinder when the throttle valve 103b is fully opened is calculated. .
In the m4 portion, the fresh air ratio η is calculated with reference to a map as shown in the figure based on the intake valve passage volume flow ratio RQH0VEL and the engine speed NE when the throttle valve 103b is throttled. To do.

In part m5, the amount of air TP100 sucked into the cylinder when the throttle valve 103b is fully opened is multiplied by the fresh air ratio η to calculate “TP100 · η”. In part m6, “TP / (TP100 · η) ”is calculated.
“TP / (TP100 · η)” indicates the pressure ratio Pm′1 / Pa when the variable valve lift mechanism (VEL) 112 is operated.

Further, in section m7, based on the pressure ratio Pm′1 / Pa when the variable valve lift mechanism (VEL) 112 is operated, the table TKPA1 shown in the figure is searched to calculate the coefficient KPA1.
The m8 part sets the correction value KAVEL by dividing the coefficient KAP0 calculated in the m2 part by the coefficient KAP1 calculated in the m7 part, and outputs it to the M part in FIG.

Next, calculation of the intake valve passage volume flow ratio WQH0VEL and the actual volume flow ratio RQH0VEL will be described based on the block diagram of FIG.
In the section m10, based on the operating angle VELREAL (control amount) of the control shaft 16 of the variable valve lift mechanism (VEL) 112, a table TAAVEL0 as shown in the figure is searched to calculate the opening area AAVEL0 of the intake valve 105. .

In the section m11, similarly to the section G in FIG. 14, the opening area AAVEL0 is divided by the correction value KHOSNE corresponding to the engine rotational speed Ne to calculate AAVEL.
Then, the calculated AAVEL is divided by the engine speed NE at m12, and is divided by the displacement (cylinder volume) VOL # at m13.
In the section m14, a table TWH0VEL0 as shown in the figure is searched, and AAVEL / NE / VOL # is converted into a volume flow ratio WH0VEL0.

Then, in the m15 part, similarly to the E part of FIG. 14, the correction by the correction value KHOSIVC is performed on the volume flow ratio WH0VEL0 to calculate the intake valve passage volume flow ratio WQH0VEL when the throttle valve 103b is fully opened. Output to 18 m3 parts.
On the other hand, in m16 part, AAVEL 'is calculated by multiplying AAVEL calculated in m11 part by the ratio (Pm / Pa) of actual intake manifold pressure Pm and atmospheric pressure Pa.

Then, the AAVEL ′ is divided by the engine rotational speed Ne at m17, and is divided by the displacement (cylinder volume) VOL # at m18.
In the m19 part, as in the m14 part, the table TRH0VEL0 as shown in the figure is searched to convert AAVEL '/ NE / VOL # into the volume flow ratio RH0VEL0.
Then, in m20 part, similarly to m15 part (E part in FIG. 14), correction by the correction value KHOSIVC is performed on the volume flow rate ratio RH0VEL0 to calculate the actual volume flow ratio RQH0VEL, and m4 part in FIG. Output to.

Next, fuel injection control by the control unit (C / U) 115 will be described.
As shown in FIG. 1, when the vehicle engine 101 includes a port injection type fuel injection valve 121 and an in-cylinder direct injection type fuel injection valve 122 in each cylinder, the exhaust stroke per cycle of each cylinder. The first injection performed by the port injection type fuel injection valve 121 during the middle (for example, the middle stage of the exhaust stroke), and the second injection performed by the direct injection fuel injection valve 122 in the vicinity of the closing timing of the intake valve 105 The fuel injection is performed in two times, and an air-fuel mixture is formed by the sum of the fuel injected by the first injection and the fuel injected by the second injection (see FIG. 20).

The first injection by the port injection type fuel injection valve 121 is not limited to the exhaust stroke and may be in the initial stage of the intake stroke, but by injecting as early as possible, Heat can be used to promote vaporization of the fuel, and the fuel can be evenly distributed in the combustion chamber during the intake stroke.
On the other hand, when the vehicular engine 101 includes only the in-cylinder direct injection fuel injection valve 122 in each cylinder as shown in FIG. 2, the intake stroke initial stage (exhaust valve closing) per cycle of each cylinder. 2) the first injection performed by the in-cylinder direct injection fuel injection valve 122 and the second injection performed by the in-cylinder direct injection fuel injection valve 122 in the vicinity of the closing timing of the intake valve 105. Fuel injection is performed separately, and an air-fuel mixture is formed by the sum of the fuel injected by the first injection and the fuel injected by the second injection (see FIG. 21).

When the engine 101 includes only the in-cylinder direct injection type fuel injection valve 122, if the fuel injection by the in-cylinder direct injection type fuel injection valve 122 is performed during the exhaust stroke in which the exhaust valve 107 is open, the injected fuel Is discharged from the combustion chamber 106 as it is through the exhaust valve 107.
Therefore, although it is desired that the first injection is performed as early as possible so that the fuel is evenly distributed in the combustion chamber, in the engine 101 having only the in-cylinder direct injection fuel injection valve 122, the earliest injection timing is the exhaust gas. After the valve 107 is closed, the first injection is performed at a timing immediately after the exhaust valve 107 is closed.

Further, as described above, the second injection is performed in the vicinity of the closing timing of the intake valve 105. This is because the change in the opening characteristic of the intake valve 105 after the first injection (variable valve lift mechanism (VEL)). 112 and the operation of the variable valve timing mechanism (VTC) 114), the sum of the injection amounts per cycle is changed in accordance with the change in the intake air amount.
Here, since the cylinder intake air amount in the intake stroke is determined at the closing timing of the intake valve 105, the calculation of the second injection amount is performed at the closing timing of the intake valve 105 or immediately before the closing timing or What is performed after the valve is closed is required for obtaining the fuel injection amount corresponding to the actual intake air amount.

On the other hand, although injection by the direct injection fuel injection valve 122 is possible until immediately before ignition, in order to form a uniform mixture, it is required to inject as early as possible. It is desired to inject immediately and to calculate the injection amount as early as possible.
Therefore, in this embodiment, the vicinity of the closing timing of the intake valve 105 is determined as the injection timing, and the injection is performed immediately after the calculation of the injection amount. It can be formed.

The start timings of the first and second injections are detected based on signals from the crank angle sensor 118 and the cam angle sensor 119.
When the first injection starts at a preset first injection start timing, that is, during the exhaust stroke for port injection, or immediately after the exhaust valve 107 is closed for in-cylinder injection, the fuel injection amount (first injection amount) ) Ti is calculated and an injection pulse having a pulse width corresponding to the fuel injection amount (first injection amount) Ti is injected into the port injection type fuel injection valve 121 provided in the cylinder at the injection start timing or in-cylinder direct injection. This is done by outputting to the fuel injection valve 122.

The fuel injection amount (first injection amount) Ti is, as will be described in detail later, a basic fuel injection amount Tp, various correction coefficients COEF, a port wall flow correction amount Tvelp, a cylinder wall flow correction amount Tvels, and an invalid injection pulse amount. It is calculated as Ti = Tp × COEF + Tvelp + Tvels + Ts + Tveli−Tveldef from Ts, the increase / decrease correction share Tveli, and the basic share amount Tveldef at the end of the intake stroke.
Here, the basic share amount Tveldef at the end of the intake stroke is a basic value of the fuel amount to be injected in the second injection, and among the fuel amounts corresponding to the cylinder intake air amount at the timing of the first injection, the intake stroke end The amount excluding the time basic sharing amount Tveldef is injected by the first injection, the remaining Tveldef is injected by the second injection, the first injection amount injected by the first injection, and the second injection injected thereafter. The sum of the two injection amounts is an amount commensurate with the cylinder intake air amount in a steady state so that an air-fuel mixture having a target air-fuel ratio is formed.

The flowchart of FIG. 22 shows the control of the first injection.
The routine shown in the flowchart of FIG. 22 is interrupted when the crank angle sensor 118 detects that the injection start timing (injection start crank angle) in the first injection is set in advance. ing.
As described above, when the port injection type fuel injection valve 121 is provided, the injection start timing in the first injection is the fixed crank angle position during the exhaust stroke or the engine operating state (engine load, engine rotation speed). The crank angle position between the exhaust stroke and the initial stage of the intake stroke is variably set from the engine temperature.

Further, in an engine provided with only the direct injection type fuel injection valve 122, the fixed crank angle position is set immediately after the exhaust valve 107 is closed (including the closing timing).
When the injection start timing in the first injection is started and the interruption process of the routine shown in the flowchart of FIG. 22 is started, first, in step S1001, the intake valve 105 after the first injection is close to the closing timing. The injection start timing of the second injection is determined.

Specifically, as shown in FIG. 23, the variable valve timing mechanism (VTC) 114 is controlled to the most retarded angle from the operating angle (VEL angle) of the control shaft 16 of the variable valve lift mechanism (VEL) 112 at that time. The valve closing timing IVC (ATDC angle) of the intake valve 105 when it is assumed that the intake valve 105 is assumed is obtained.
The valve closing timing IVC is corrected by the advance amount (VTC angle) of the rotational phase of the camshaft 113 by the variable valve timing mechanism (VTC) 114 at that time, so that the variable valve lift mechanism (VEL) at that time is corrected. ) 112 and the valve closing timing IVC of the intake valve 105 in the control state of the variable valve timing mechanism (VTC) 114 are obtained.

Further, as the engine rotational speed NE is lower, the angular position that is retarded from the currently estimated valve closing timing IVC is set as the start timing of the second injection with the retardation correction value corresponding to the engine rotational speed NE. The result of delay angle correction of the valve closing timing IVC is set as the start timing of the second injection.
When the engine speed NE is high, the time from the first injection timing to the valve closing timing IVC of the intake valve 105 is short, and even after the first injection timing, the variable valve lift mechanism (VEL) 112 changes the valve lift amount. Even if the operation is performed, the actual valve closing timing does not greatly deviate from the valve closing timing IVC of the intake valve 105 predicted at the time of the first injection timing.

  On the other hand, when the engine speed NE is low, the time from the first injection timing to the valve closing timing IVC of the intake valve 105 is long, and the variable valve lift mechanism (VEL) 112 changes the valve lift amount after the first injection timing. By performing this operation, there is a possibility that the actual valve closing timing is significantly deviated from the valve closing timing IVC of the intake valve 105 predicted at the time of the first injection timing.

  At the time of acceleration for increasing the valve lift, the actual valve closing timing is greatly delayed from the valve closing timing IVC of the intake valve 105 predicted at the time of the first injection timing, and is predicted at the time of the first injection timing. Assuming that the closing timing IVC of the intake valve 105 is the second injection timing, the second injection is actually performed before the closing timing of the intake valve 105.

  As will be described later, the injection amount of the second injection is corrected in accordance with the change in the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 after the first injection. If the second injection timing is an angular position advanced from the actual valve closing timing at the time of acceleration, the second injection amount is set corresponding to the increase change in the cylinder intake air amount from the first injection timing to that time. As a result, the fuel corresponding to the cylinder intake air amount finally determined at the closing timing of the intake valve 105 cannot be injected, and as a result, the air-fuel ratio is made lean. .

  Therefore, especially at the time of acceleration for increasing the valve lift, the second injection timing is greatly delayed as the engine speed is low, in order to avoid setting the second injection timing to a position that is advanced more than the actual valve closing timing. Even if the variable valve lift mechanism (VEL) 112 operates in the increasing direction of the valve lift after the first injection timing, the second injection timing is set near the actual valve closing timing.

  In addition to or instead of the correction based on the engine rotational speed NE, information on the degree of transient operation correlated with the change rate of the valve lift amount (for example, the change rate of the accelerator opening, the change rate of the target volume flow ratio, The valve closing timing IVC estimated from the control state at the first injection timing of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 is corrected based on the change speed of the target angle of the control shaft 16. The correction result can be set as the second injection timing.

In step S1001, the valve closing timing is obtained from the operating angle of the control shaft 16 of the variable valve lift mechanism (VEL) 112 and the advance amount of the rotational phase of the cam shaft 113 by the variable valve timing mechanism (VTC) 114. An angle IVCANGz from the injection start timing of the first injection to the valve closing timing is obtained and stored.
In the next step S1002, a basic fuel injection amount (basic injection pulse width) Tp is calculated.

The basic fuel injection amount (basic injection pulse width) Tp is calculated by using the intake air amount Qa detected by the engine speed NE and the air flow meter (AF / M) 117 and the constant K, and Tp = Qa / Ne × K. Is calculated as
That is, the basic fuel injection amount (basic injection pulse width) Tp is the total fuel amount required to form a target air-fuel ratio mixture with respect to the cylinder intake air amount measured at that time.

In step S1003, various correction coefficients COEF for correcting the basic fuel injection amount (basic injection pulse width) Tp are calculated.
The various correction factors COEF are: start-up and post-start-up increase Kas for increasing the fuel amount during and immediately after start-up, water temperature increase rate Ktw for increasing the fuel amount at low water temperature (cold), high-load high-rotation operation High load high rotation increase rate KMR for generating output while suppressing increase in exhaust temperature by sometimes increasing fuel temperature, Increase rate KHOT at high water temperature for increasing fuel at high water temperature to suppress increase in exhaust temperature, etc. Is calculated as COEF = Kas + Ktw + KMR + KHOT.

In step S1004, a port wall flow correction amount Tvelp for correcting the basic fuel injection amount (basic injection pulse width) Tp according to a change in the port wall flow rate is calculated.
The calculation of the port wall flow correction amount Tvelp is shown in detail in the flowchart of FIG.
In step S2011, the engine speed NE, the basic injection pulse width (basic fuel injection amount) Tp representative of the engine load, the water temperature Tw, the throttle valve opening TVO, and the operating angle (valve lift amount) of the control shaft 16 are input.

In step S2012, a port wall flow correction basic value is calculated based on the engine rotational speed Ne, basic injection pulse width Tp, water temperature Tw, and throttle valve opening TVO.
Specifically, as shown in FIG. 25, the engine rotation before the accelerator operation (immediately before the transient operation) is obtained from a map storing the equilibrium adhesion amount of the port wall flow corresponding to the engine rotation speed NE and the basic injection pulse width Tp. The equilibrium adhesion amount corresponding to the speed Ne and the basic injection pulse width Tp and the equilibrium adhesion amount corresponding to the engine speed NE and the basic injection pulse width Tp after the accelerator operation (during transient operation) are searched.

Note that the amount of equilibrium adhesion of the port wall flow is set to a larger value as the load becomes lower.
Then, the basic correction value is calculated as basic correction value = equilibrium adhesion amount (after accelerator operation) −equilibrium adhesion amount (before accelerator operation).
On the other hand, as shown in FIG. 26, the lower the water temperature Tw, the larger the water temperature correction coefficient is set. Further, as shown in FIG. 27, the amount of change (change speed) ΔTVO per unit time of the throttle valve opening TVO is A larger ΔTVO coefficient is set as the value is larger.

Then, the port wall flow correction basic value is calculated as port wall flow correction basic value = basic correction value × water temperature correction coefficient × ΔTVO coefficient.
In step S2013, a VEL correction amount is set according to the operating angle of the control shaft 16.
In this embodiment, it is assumed that the valve lift amount of the intake valve 105 increases as the operating angle of the control shaft 16 increases, and the VEL correction amount is a control shaft that increases the valve lift amount as shown in the flowchart. A larger value is set as the operating angle of 16 is larger.

The VEL correction amount is such that when the valve lift amount is small, the flow rate of the intake air passing through the intake valve 105 is high, and the fuel adhering to the wall surface of the intake port near the intake valve 105 is easily sucked out. It corresponds to the wall flow rate being reduced.
In step S2014, the port wall flow correction amount Tvelp is calculated as Tvelp = port wall flow correction basic value × VEL correction amount.

Returning to the flowchart of FIG. 22 and continuing the description, in step S1005, the cylinder inner wall flow correction amount Tvels for correcting the basic fuel injection amount (basic injection pulse width) Tp in accordance with the change in the cylinder inner wall flow rate is calculated. To do.
The calculation of the cylinder wall flow correction amount Tvels is shown in detail in the flowchart of FIG.
In step S3021, the engine speed Ne, the basic injection pulse width (basic fuel injection amount) Tp representative of the engine load, the water temperature Tw, the throttle valve opening TVO, the operating angle (valve lift amount) of the control shaft 16 and after the start. Enter the elapsed time of.

In step S3022, the cylinder inner wall flow correction basic value is calculated based on the engine speed Ne, the basic injection pulse width Tp, the water temperature Tw, the throttle valve opening TVO, and the elapsed time after the start.
Specifically, as shown in FIG. 29, the engine rotation before the accelerator operation (immediately before the transient operation) is obtained from a map in which the equilibrium adhesion amount of the cylinder inner wall flow is stored corresponding to the engine rotation speed Ne and the basic injection pulse width Tp. The equilibrium adhesion amount corresponding to the speed Ne and the basic injection pulse width Tp and the equilibrium adhesion amount corresponding to the engine rotational speed Ne and the basic injection pulse width Tp after the accelerator operation (during transient operation) are searched.

Note that the amount of equilibrium adhesion of the cylinder inner wall flow is set to a larger value when the rotation is low and the load is low.
Then, the basic correction value is calculated as basic correction value = equilibrium adhesion amount (after accelerator operation) −equilibrium adhesion amount (before accelerator operation).
On the other hand, as shown in FIG. 26, the lower the water temperature Tw, the larger the water temperature correction coefficient is set. Further, as shown in FIG. 27, the amount of change (change speed) ΔTVO per unit time of the throttle valve opening TVO is A larger ΔTVO coefficient is set as the value is larger.

Further, a post-start time coefficient is set according to the elapsed time from the start. As shown in FIG. 30, the post-start time coefficient is set to a smaller value as the elapsed time from the start becomes longer.
Then, the cylinder wall flow correction basic value is calculated as cylinder wall flow correction basic value = basic correction value × water temperature correction coefficient × ΔTVO coefficient × time coefficient after start.

In step S <b> 3023, a VEL correction amount is set according to the operating angle of the control shaft 16.
As shown in the flowchart, the VEL correction amount is set to a smaller value as the operating angle of the control shaft 16 that increases the valve lift amount is larger.
The VEL correction amount used for correcting the cylinder wall flow correction basic value is such that the flow of the intake air when passing through the intake valve is directed toward the periphery under the condition that the valve lift amount is small (the diameter from the center of the umbrella portion of the intake valve 105). This corresponds to an increase in the in-cylinder attached wall flow rate.

In step S3024, the cylinder inner wall flow correction amount Tvels is calculated as Tvels = cylinder inner wall flow correction basic value × VEL correction amount.
As described above, in the calculation of the port wall flow correction amount Tvelp and the cylinder inner wall flow correction amount Tvels, the correction according to the valve lift amount of the intake valve 105 is performed, so that the port wall flow rate and the cylinder inner wall due to the change in the valve lift amount are obtained. The fuel injection amount can be appropriately corrected in accordance with the change in the flow rate, and the air-fuel ratio control accuracy during the transition can be improved.

Returning to the flowchart of FIG. 22 and continuing the description, in step S1006, an invalid injection pulse portion Ts is calculated.
The invalid injection pulse Ts is a correction value for dealing with a change in the valve opening delay time of the fuel injection valves 121 and 122 due to the voltage of the battery that is the power source of the fuel injection valve 121, and the fuel voltage is low. A larger value is set as the valve opening delay time of the valves 121 and 122 becomes longer.

In step S1007, an increase / decrease correction share Tveli is calculated.
In this embodiment, as will be described later, the injection amount increase / decrease correction corresponding to the increase / decrease change in the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 after calculating the first injection amount Ti, By applying to the second injection amount in the second injection, a mixture of the target air-fuel ratio is formed with the changed cylinder intake air amount.

  However, since the second injection is performed in the vicinity of the closing timing of the intake valve 105 as described above, it is difficult to evenly distribute the fuel injected by the second injection in the combustion chamber 106 and the combustion. In order to form a homogeneous air-fuel mixture in the chamber 106, it is desirable to inject as much fuel as possible from the amount of fuel required for forming the air-fuel mixture with the target air-fuel ratio in the first injection.

Therefore, in the previous second injection, the amount calculated as an increase / decrease correction amount corresponding to the increase / decrease change amount of the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 after calculating the first injection amount. A certain ratio is injected by the first injection in the next cycle, and the amount of fuel to be injected by the second injection is reduced.
That is, the increase / decrease correction share is calculated from the increase / decrease correction amount Tintbas corresponding to the change in the cylinder intake air amount after the first injection calculated at the previous injection start timing of the second injection and the preset ratio Ratio. The minute Tveli is calculated as Tveli = Tintbas × Ratio.

The ratio Ratio may be a fixed value or may be set to a larger value as the acceleration is accelerated.
The increase / decrease correction amount Tintbas will be described in detail later.
In step S1008, the basic share amount Tveldef at the end of the intake stroke is calculated.
The basic share amount Tveldef at the end of the intake stroke is a basic value of the second injection amount that is injected by the second injection even during steady operation of the engine 101, and is set according to the operating state of the engine 101.

Specifically, as shown in the map shown in FIG. 31, the basic share amount Tveldef at the end of the intake stroke depends on the engine speed Ne and the basic injection pulse width (basic fuel injection amount) Tp representative of the engine load. It is set in advance, and is set to a larger value at the time of low rotation / high load, and is set to zero in the low rotation / low load region, middle / high rotation / low load, and high rotation / medium / high load region.
The region where the basic share amount Tveldef is set to zero is an operation region that is generally used in steady operation, and since it enters an operation region where the basic share amount Tveldef> 0 by acceleration, it is substantially When the cylinder intake air amount is increased after the first injection is performed, the basic share amount Tveldef> 0 is set, and the correction of the injection amount by the second injection is unnecessary, The second injection is not performed.

It should be noted that the basic share amount Tveldef at the end of the intake stroke can be set to a different value at the time of acceleration and at the time of deceleration. Specifically, at the time of acceleration, the share amount Tveldef can be made smaller than that at the time of deceleration.
This is because when the cylinder intake air amount decreases with deceleration, the reduction margin needs to be secured in advance in the second injection in order to cope with the decrease change, whereas during acceleration, the cylinder intake air This is because additional fuel may be injected in response to an increase in the air amount, and the shared amount Tveldef may be zero.

Even if the fuel is reduced at the timing of the second injection, the maximum amount can be reduced only to the basic share amount Tveldef. If the basic share amount Tveldef is small, the fuel is already injected even if the second injection amount is reduced to the maximum. There is a possibility that the air-fuel ratio is enriched only by the first injection amount, and the second injection amount needs to be larger than the amount to be reduced.
Therefore, acceleration / deceleration operation is discriminated, and during acceleration, the sharing amount Tveldef is set to zero or about the minimum injection amount, and during deceleration, acceleration is performed as a fixed value (> 0) or a variable value according to the engine load, engine speed, etc. It is possible to set a sharing amount Tveldef larger than the time.
Furthermore, by increasing the sharing amount Tveldef during rapid deceleration, the sharing amount Tveldef can be increased in advance when the change in the cylinder intake air amount after the first injection is large.

The determination of the rapid deceleration can be made based on a state quantity that correlates with the change speed of the cylinder intake air amount, such as the change speed of the accelerator opening or the angular speed of the control shaft 16.
In step S1009, a fuel injection amount (first injection amount) Ti is calculated according to the following equation based on the calculation results of steps S1002 to S1008.
Formula (2) ... Ti = Tp * COEF + Tvelp + Tvels + Ts + Tveli-Tveldef
In step S1010, an injection pulse signal having a pulse width corresponding to the fuel injection amount (first injection amount) Ti is sent to the port injection type fuel injection valve 121 provided in the cylinder at the start timing of the first injection or in the cylinder. Output to the direct injection type fuel injection valve 122.

  In the engine (see FIG. 1) provided with the in-cylinder direct injection type fuel injection valve 122 and the port injection type fuel injection valve 121, the first injection timing is set during the exhaust stroke, and the first injection start timing during this exhaust stroke. Then, the fuel injection amount (first injection amount) Ti is calculated, and the injection of the fuel injection amount (first injection amount) Ti is immediately started by the port injection type fuel injection valve 121.

  On the other hand, in an engine (see FIG. 2) having only the direct injection type fuel injection valve 122, the first injection timing is set immediately after the exhaust valve 107 is closed, and the first injection timing immediately after the exhaust valve 107 is closed. At the injection start timing, the fuel injection amount (first injection amount) Ti is calculated, and the injection of the fuel injection amount (first injection amount) Ti is immediately performed by the in-cylinder direct injection type fuel injection valve 122. Let it begin.

However, the calculation of the fuel injection amount (first injection amount) Ti is repeatedly executed at regular intervals, and when the crank angle corresponding to the first injection timing is reached, the latest calculated fuel injection amount (first The first injection can be performed based on the injection amount Ti.
In step S1011, the latest value of the intake valve passage volume flow rate ratio WQH0VEL is stored as the value WQH0VELz at the time of the first injection.

The intake valve passage volume flow ratio WQH0VEL corresponds to an intake air amount estimated based on an angle of the control shaft 16 (a control amount of the variable valve lift mechanism (VEL) 112).
The routine shown in the flowchart of FIG. 32 is a routine for controlling the second injection, and it is detected based on the signal from the crank angle sensor 118 that the injection start timing of the second injection calculated in step S1001 has come. When it happens, an interrupt is executed.

When the interrupt process is started at the start timing of the second injection, first, in step S1101, the start timing of the first injection, in other words, the fuel injection amount (first injection amount) Ti in the first injection. The correction amount Tintbas, which is the injection amount corresponding to the change in the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 after the determination is made, is calculated.
In the steady state, the first injection amount is set to an amount obtained by subtracting the basic share amount Tveldef from the cylinder intake air equivalent amount at that time, and the second injection is performed by the basic share amount Tveldef. The sum of the two injection amounts is an amount commensurate with the cylinder intake air amount at that time.

  However, if there is an operation of the variable valve lift mechanism (VEL) 112 that changes the cylinder intake air amount from the timing when the first injection amount is calculated until the intake valve 105 closes, If the second injection is performed by the basic share amount Tveldef, the change in the cylinder intake air amount cannot be dealt with, and an error occurs in the injection amount corresponding to the changed cylinder intake air amount.

That is, when control is performed to change the valve lift after calculating the first injection amount, the actual amount of cylinder intake air is determined when the intake valve 105 is closed. And the intake air amount measured during the first injection is different from the intake air amount. As a result, the required injection amount determined during the first injection becomes excessive or insufficient.
Therefore, in the present embodiment, the timing of the second injection is set near the closing timing of the intake valve 105 where the cylinder intake air amount is finally determined, and the cylinder intake air amount is determined at the timing of the second injection. By correcting the second injection amount by the amount of change in the cylinder intake air amount from the injection timing to the second injection timing, the amount of fuel corresponding to the amount of air actually sucked into the cylinder becomes the first injection amount. The sum is obtained with the second injection amount.

  For example, when the valve lift changes in the increasing direction at the time of acceleration, the control shaft 16 rotates in the lift increasing direction even after the first injection amount is determined, so that the cylinder is determined when the intake valve 105 is closed. Since the intake air amount is larger than the cylinder intake air amount at the time of determining the first injection amount, the second injection amount is increased by a correction amount Tintbas corresponding to the increase change in the cylinder intake air amount, An amount of fuel corresponding to the cylinder intake air amount is injected.

  Since the second injection is performed near the closing timing of the intake valve 105, it is difficult to evenly distribute the fuel injected by the second injection in the combustion chamber 106, but the required injection amount Most of the fuel is injected by the first injection during the exhaust stroke or immediately after the exhaust valve is closed, so that the fuel can be distributed substantially uniformly in the combustion chamber 106, and the combustion chamber 106 is obtained by the first injection and the second injection. The air-fuel mixture formed inside can be a homogeneous air-fuel mixture.

In particular, when the port injection type fuel injection valve 121 is provided and the first injection is performed during the exhaust stroke, the fuel spray vaporized using the heat of the intake port 102 is put on the air flow during the intake stroke. Thus, it can be distributed substantially uniformly in the combustion chamber 106, and the air-fuel mixture formed in the combustion chamber 106 by the first injection and the second injection can be made more uniform.
The correction amount Tintbas is calculated as follows using the intake valve passage volume flow ratio WQH0VEL calculated according to the block diagram of FIG.

  First, the latest value of the intake valve passage volume flow ratio WQH0VEL, in other words, the control of the variable valve lift mechanism (VEL) 112 (variable valve mechanism) near the closing timing of the intake valve 105, which is the start timing of the second injection. Changes in the cylinder intake air amount estimated from the amount, the intake valve passage volume flow rate ratio WQH0VELz calculated at the start timing of the first injection (when determining the first injection amount), and the closing timing IVC of the intake valve 105 A change amount DWQH0VEL of the cylinder intake air amount from the first injection start timing (when determining the first injection amount) is calculated based on the gain GAIN based on the gain GAIN.

Formula (3) ... DWQH0VEL = (WQH0VEL−WQH0VELz) × GAIN
The gain GAIN is calculated as GAIN = IVCANGnew / IVCANGz.
Here, the angle IVCANG is an angle from the start timing of the first injection (when the first injection amount is determined) to the valve closing timing IVC of the intake valve 105, and the IVCANGnew is at the start timing of the second injection. The value is based on the valve closing timing IVC predicted according to the control amounts of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114, and the IVCANGz is the first injection start timing (the first injection amount of the first injection amount). This value is based on the valve closing timing IVC predicted according to the control amounts of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 at the time of determination.

  That is, the gain GAIN is the ratio of the valve closing timing predicted when the second injection start timing is reached to the valve closing timing predicted at the first injection start timing. The valve closing timing predicted at the time when the second injection start timing is more retarded than the valve closing timing predicted at the start timing, and when IVCANGnew> IVCANGz, a value exceeding 1 is set. On the contrary, when the valve closing timing predicted at the time when the second injection start timing is advanced with respect to the valve closing timing predicted at the start timing of the first injection, and IVCANGnew <IVCANGz, It is set to a value less than 1.

  The start timing of the second injection is set to a crank angle position corresponding to the valve closing timing IVC predicted according to the control amounts of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 at the start timing of the first injection. However, the control state of the variable valve lift mechanism (VEL) 112 and / or the variable valve timing mechanism (VTC) 114 changes from the start timing of the first injection to the second injection start timing, and the intake valve When the valve closing timing 105 changes, the relative position between the start timing of the second injection and the valve closing timing of the intake valve 105 changes.

  The control state of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 does not change from the start timing of the first injection, and the intake valve 105 is actually operated at the valve closing timing predicted at the start timing of the first injection. When closed, the second injection timing substantially coincides with the closing timing of the intake valve 105, and the intake valve passage volume flow ratio WQH0VEL at that time substantially represents the final cylinder intake air amount in the current intake stroke. It will be.

  However, for example, when the valve closing timing of the intake valve 105 changes from the angular position predicted at the time of the start timing of the first injection, the second injection start timing is relatively greater than the valve closing timing of the intake valve 105. When the control state of the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 continues to change even after the second injection timing, the intake valve passage volume flow rate ratio WQH0VEL at the second injection timing Does not represent the final cylinder intake air amount in the intake stroke of this time, but indicates the course of the changing cylinder intake air amount.

  On the other hand, if it is assumed that the change in the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 between the first injection start timing and the second injection start timing continues at a rate until then, WQH0VEL− When the change in air amount per unit crank angle obtained by dividing WQH0VELz by IVCANGz is multiplied by IVCANGnew, the change in air amount in IVCANGnew, in other words, the start timing of the second injection from the start timing of the first injection. The change in the air amount until the valve closing timing predicted in step 1 is obtained.

  Therefore, for example, even if the valve closing timing of the intake valve 105 is greatly retarded due to an increase in the valve lift amount accompanying acceleration, the first injection timing is increased even if the second injection start timing is relatively advanced from the valve closing timing. The change corresponding to the deviation between the cylinder intake air amount estimated from the control state of the variable valve lift mechanism (VEL) 112 in the engine and the cylinder intake air amount corresponding to the control state of the variable valve lift mechanism (VEL) 112 at the valve closing timing. The amount DWQH0VEL can be obtained at the second injection start timing.

  In the present embodiment, a variable valve lift mechanism (VEL) 112 and a variable valve timing mechanism (VTC) 114 are provided as variable valve mechanisms that vary the opening characteristics of the intake valve 105, and the intake valve 105 is bottom dead. In the case of closing before the point, the intake air amount increases as the closing timing of the intake valve 105 delays (closer to the bottom dead center) and the valve lift amount of the intake valve 105 increases. Is closed after the bottom dead center, the intake air amount increases as the closing timing of the intake valve 105 advances (closer to the bottom dead center) and the valve lift amount of the intake valve 105 increases.

  Here, in the present embodiment, the intake valve passage volume flow rate ratio WQH0VEL obtained based on the operating angle VELREAL (control amount) of the control shaft 16 of the variable variable valve lift mechanism (VEL) 112, and the variable valve lift mechanism (VEL). 112 and the gain GAIN based on the valve closing timing IVC predicted according to the control amount of the variable valve timing mechanism (VTC) 114, the change amount DWQH0VEL is obtained substantially, and thus the variable valve lift mechanism (VEL) 112 and the variable valve timing mechanism (VTC) 114 can estimate the change in the intake air amount.

If only the variable valve timing mechanism (VTC) 114 is provided as the variable valve mechanism, the second injection amount can be determined by estimating the change in the intake air amount from the change in the closing timing of the intake valve 105. it can.
When the change amount DWQH0VEL is obtained as described above, the deviation DWQH0VEL as the volume flow rate is then converted into the deviation DMASCYL as the mass flow rate by the coefficient AIRSPG.

Expression (4): DMASCYL = DWQH0VEL × AIRSPG
The coefficient AIRSPG is calculated according to the following equation based on the intake air temperature and the intake manifold pressure.
Formula (5)... AIRSPG = (1.293 / (1 + 0.00367 × intake air temperature ° C.)) × intake manifold pressure kPa / 101.3 kPa
Further, the deviation DMASCYL is corrected based on a coefficient K for converting the intake air amount into a fuel injection amount equivalent to the target air-fuel ratio and a correction coefficient HOSEI set according to the water temperature, and the result is corrected. Let the minute Tintbas.

Expression (6) Tintbas = DMASCYL × K × HOSEI
As shown in FIG. 33, the correction coefficient HOSEI is set to 1.0 when the temperature is high, and is set to a value larger than 1.0 as the temperature becomes low.
In the increase correction by the correction coefficient HOSEI, similarly to the various correction coefficients COEF (water temperature increase rate Ktw) in the fuel injection amount (first injection amount) Ti, the correction amount Tintbas is increased and corrected as the temperature is lower.

In step S1102, the increase / decrease correction share Tveli set in step S1007 is read, and in the next step S1103, the intake stroke end basic share amount Tveldef set in step S1008 is read.
In step S1104, the second injection amount Tint is calculated according to the following equation.
Expression (7): Tint = Tveldef + Tintbas-Tveli
As described above, the second injection amount Tint is based on the basic share amount Tveldef at the end of the intake stroke, and only the change Tintbas of the air amount from when the first injection amount is determined until the intake valve 105 is closed. It corrects and subtracts and corrects Tveli, which is the amount by which the first injection amount is transferred in the change amount Tintbas.

The increase / decrease correction share Tveli is set as Tveli = Tintbas × Ratio as described above. For example, a predetermined ratio of Tintbas obtained at the current second injection timing is added to the next first injection. Accordingly, the second injection amount is subtracted by the amount of Tveli added to the first injection amount, so that the total amount is not changed.
As described above, if the first injection amount is corrected by the increase / decrease correction share Tveli, the variable valve lift mechanism (VEL) 112 operates and the valve lift amount of the intake valve 105 continues to change. The first injection amount is corrected in anticipation of an increase in the cylinder intake air amount after the first injection, and the amount of fuel that needs to be injected in the second injection is relatively reduced. .

Here, in order to form a homogeneous air-fuel mixture, fuel injection at an early timing is desired. Therefore, the homogenization of the air-fuel mixture can be improved by increasing the amount of fuel injected in the first injection as much as possible. Can be made.
However, if the increase / decrease correction share Tveli is excessive, the first injection amount may be excessively corrected when shifting from the transient operation in which the intake air amount changes to the steady operation in which the intake air amount hardly changes. Therefore, the ratio Ratio is adapted in advance through experiments and simulations so as not to overcorrect the first injection amount.

  The ratio Ratio can be a fixed value. For example, the cylinder intake air such as the changing speed of the accelerator opening or the operating speed of the variable valve lift mechanism (VEL) 112 (specifically, the angular speed of the control shaft 16). The ratio Ratio can be set to a larger value under the condition that the change speed of the cylinder intake air amount becomes faster.

FIG. 34 shows changes in Ti, Tintbas, and Tveli during acceleration. Here, the ratio Ratio = 0.5.
At the time of acceleration, the basic share amount Tveldef at the end of the intake stroke is corrected by an amount corresponding to an increase change in the cylinder intake air amount from the start timing of the first injection to the closing timing of the intake valve 105 to determine the second injection amount Tint. Is done.

  Specifically, when Tintbas = A (ms) is calculated at the start timing of the second injection by the start of acceleration, the second injection amount at that time is determined as Tint = Tveldef + A-0, While Tveli = A × 0.5 is added to the injection amount, and Tintbas = B (ms) is calculated at the start timing of the next second injection, the second injection amount is Tint = Tveldef + B−. A × 0.5 is determined.

Further, in the next first injection, Tveli = B × 0.5 is added. On the other hand, when Tintbas = C (ms) is calculated at the start timing of the next second injection, Tint = Tveldef + C−B X is determined to be 0.5.
On the other hand, at the time of deceleration, as shown in FIG. 35, the basic allocation amount Tveldef at the end of the intake stroke is corrected to decrease by the decrease change in the cylinder intake air amount from the start timing of the first injection to the closing timing of the intake valve 105. As a result, the total injection amount of the first injection and the second injection is reduced from the expected amount at the time of the first injection.

  Since the valve operating angle decreases as the valve lift amount decreases due to the deceleration operation, the closing timing of the intake valve 105 advances during the deceleration operation, and the second injection determined at the start timing of the first injection. However, since the second injection is performed by the direct injection type fuel injection valve 122, the second injection is performed during the compression stroke. Can be burned in that cycle.

When the second injection amount Tint is calculated as described above in step S1104, in step S1105, an injection pulse signal having a pulse width corresponding to the second injection amount Tint is supplied to the cylinder fuel at the end of the intake stroke at that time. It outputs to the injection valve 122 and fuel injection is started.
In the next step S1106, the correction amount Tintbas calculated this time is stored in order to correct the next first injection amount Ti based on the correction amount Tintbas calculated this time.

  According to the above embodiment, the cylinder intake air amount due to the operation of the variable valve lift mechanism (VEL) 112 from the start timing of the first injection (determination timing of the first injection amount Ti) until the intake valve 105 is closed. By correcting the second injection amount by the amount of change, the total fuel injection amount in the cycle is corrected to an amount commensurate with the amount of air actually sucked into the cylinder.

Therefore, even if the variable valve lift mechanism (VEL) 112 is operated from the start timing of the first injection (determination timing of the first injection amount Ti) until the intake valve 105 is closed, the actual cylinder intake air amount Therefore, it is possible to inject an amount of fuel substantially commensurate with the above, and to suppress deterioration in exhaust properties and reduction in power performance due to an air-fuel ratio shift.
In the case where a mechanical abnormality has occurred in the variable valve lift mechanism (VEL) 112 and it has become impossible to converge on the target valve lift, or when the response speed is greatly reduced, the control shaft When the variable valve system system is abnormal, such as when the operating angle sensor 206 that detects the angle of 16 is out of order, the second injection is stopped, and only the first injection is performed with the first injection amount Ti = Tp × COEF + Tvelp + Tvels + Ts. Or the second injection amount is limited to be equal to or less than the limit value for the fail state.

Since the amount that can be corrected by the second injection differs depending on the response speed of the variable valve lift mechanism (VEL) 112, the possibility of correction by the second injection predicted according to the response speed at that time is possible. The limit value can be set based on a certain amount.
As described above, by restricting the second injection when the system of the variable valve system is abnormal, it is possible to suppress the occurrence of an air-fuel ratio shift due to an erroneous setting of the second injection amount, and to generate a homogeneous mixture Can be prevented from being hindered by the second injection.

In addition, in the steady operation state or the slow acceleration / deceleration state, the second injection including the basic share is stopped, and even in the transient operation state, the change in the intake air amount after the first injection is small. When the correction is unnecessary or when the correction is not substantially significant, the correction of the second injection amount or the second injection for responding to the change in the intake air amount can be stopped.
Further, when the fuel cut condition such as deceleration is satisfied, the second injection is stopped together with the first injection, but the calculation of the second injection amount is continued even during the fuel cut, and the fuel injection is resumed. Sometimes, it is preferable to immediately restart the second injection in alignment with the restart control of the injection.

Further, the setting of the basic share amount Tveldef at the end of the intake stroke can be omitted (Tveldef = 0 is fixed), and the second injection as the additional injection at the time of acceleration can be performed based on the correction amount Tintbas. Correction of the first and second injection amounts by Tveli can be omitted.
Further, in the present embodiment, the change in the intake air amount after the first injection is detected based on the change in the intake valve passage volume flow ratio WQH0VEL. For example, the change in the actual intake valve passage volume flow ratio RQH0VEL is detected. Further, the second injection amount (correction amount Tintbas) is determined based on the change in the angle (control amount) of the control shaft 16 of the variable valve lift mechanism (VEL) 112 and the operation amount of the actuator (DC servo motor) 201. be able to.

The mechanism for continuously varying the valve lift amount is not limited to the variable valve lift mechanism (VEL) 112, and the actuator of the variable valve mechanism is not limited to the DC servo motor. For example, a brushless motor The second injection amount can be set from a change in the control amount or the operation amount of the variable valve mechanism to be applied.
Further, in the above embodiment, in the engine provided with the port injection type fuel injection valve 121, the first injection is performed during the exhaust stroke, but immediately after the exhaust valve 107 is closed or at the initial stage of the intake stroke (the intake valve 105). The first injection by the port injection type fuel injection valve 121 can be performed immediately after the valve is opened.

Further, the structure of the variable valve lift mechanism (VEL) 112 as the variable valve mechanism is not limited to the structure shown in FIGS. 3 to 5, and the engine is controlled by the advance / retard angle control of the closing timing of the intake valve 105. A variable valve mechanism that controls the amount of intake air may be used.
As a variable valve timing mechanism for controlling the advance / retard angle of the closing timing of the intake valve 105, in addition to the mechanism shown in FIG. 11, the valve operating angle is disclosed by Japanese Patent Laid-Open No. 2003-269124 by the magnetic force of an electromagnetic retarder. A mechanism for controlling the advancement / retarding angle of the center phase, a mechanism disclosed in Japanese Patent Application Laid-Open No. 2003-184516, and a mechanism provided with a movable guide part that is displaceably guided and engaged with a spiral guide; A known mechanism such as a mechanism for driving a camshaft by a motor as disclosed in Japanese Patent Application Laid-Open No. 2008-025541 can be appropriately employed.

In addition, as a mechanism for continuously varying the valve lift amount, for example, a mechanism disclosed in Japanese Patent Application Laid-Open No. 2001-263015 can be used.
The mechanism disclosed in Japanese Patent Laid-Open No. 2001-263015 includes a slider gear that can move in conjunction with a control shaft, an input arm that is driven by a cam of the camshaft, and an output arm that lifts the engine valve. When the slider gear moves in the axial direction in conjunction with the movement of the control shaft in the axial direction, the relative positions of the slider gear, the input arm and the output arm in the axial direction change, and the input arm on the slider gear This is a mechanism that changes the relative phase difference between the output arm and the output arm to continuously change the operating angle and lift amount of the engine valve.

Furthermore, the advance timing of the second injection start timing determined by the start timing of the first injection can be corrected based on the change in the closing timing of the intake valve 105 after the first injection.
For example, when the valve lift amount increases after the first injection at the time of acceleration, the second injection timing is determined at the time of the first injection in response to a change in the closing timing of the intake valve 105 due to the increase change. If the valve lift amount decreases after the first injection at the time of deceleration, the second injection timing is set to the first injection timing corresponding to the advance angle change of the closing timing of the intake valve 105 due to the decrease change. The angle is advanced rather than the decision at the time of injection.

  If the second injection timing is corrected as described above, it is possible to prevent the relative position between the second injection timing and the intake valve closing timing from deviating greatly, and therefore, the intake air after the first injection. The amount change can be estimated stably.

Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) The fuel injection control device for an engine according to claim 6, wherein the basic value of the second injection amount is set to a larger value as the engine speed is lower.
According to the above invention, the basic value of the second injection amount is set to a larger value as the engine speed is low, and the basic value is corrected to increase or decrease in accordance with the change in the intake air amount.

(B) The engine fuel injection control device according to claim 6 or (a), wherein the basic value of the second injection amount is set to a larger value as the engine is heavily loaded.
According to the above invention, the basic value of the second injection amount is set to a larger value as the engine is heavily loaded, and the basic value is corrected to increase or decrease in accordance with the change in the intake air amount.

(C) A fuel injection control device for an engine that includes a direct injection type fuel injection valve that directly injects fuel into a cylinder and a variable valve mechanism that varies an opening characteristic of the intake valve,
A first injection for injecting a first injection amount, and a second injection for injecting a second injection amount by the direct injection type fuel injection valve after the first injection and in the vicinity of the closing timing of the intake valve And a fuel injection control device for an engine.

According to the above invention, the fuel injection is performed in two parts, the second injection near the closing timing of the intake valve and the first injection before the second injection, and the first injection in the first injection is performed. A mixture is formed in the cycle by the sum of the injection amount and the second injection amount in the second injection.
Therefore, it is possible to change the second injection amount in the second injection performed near the closing timing of the intake valve in response to the change in the intake air amount after the calculation of the first injection amount in the first injection. The sum of the first injection amount and the second injection amount corresponds to the cylinder intake air amount in the intake stroke that is determined when the intake valve is closed, and is the amount of fuel from which a mixture of the target air-fuel ratio can be obtained. Can do.

(D) The engine fuel injection control apparatus according to claim (c), wherein the second injection amount is corrected based on an operation of the variable valve mechanism after the calculation of the first injection amount.
In the above invention, when control is performed to change the opening characteristic of the intake valve after calculating the first injection amount, the actual amount of cylinder intake air is determined when the intake valve is closed. As a result, the intake air amount is different from the intake air amount measured at the time of the first injection, and as a result, the required injection amount determined at the time of the first injection becomes excessive or insufficient.
Therefore, the second injection amount is corrected based on the operation of the variable valve mechanism after the calculation of the first injection amount.

(E) Estimated from the intake air amount estimated from the control amount of the variable valve mechanism at the calculation timing of the first injection amount, and from the control amount of the variable valve mechanism at the calculation timing of the second injection amount. The engine fuel injection control apparatus according to claim (2), wherein the second injection amount is corrected based on a deviation from the intake air amount.
According to the above invention, by correcting the second injection amount by the amount of change in the intake air amount between the timing of the first injection and the timing of the second injection, the fuel amount that matches the amount of air actually sucked into the cylinder. Is obtained as the sum of the first injection amount and the second injection amount.

(F) The calculation timing of the second injection amount is set based on the closing timing of the intake valve estimated from the control amount of the variable valve mechanism at the calculation timing of the first injection amount. Calculating a change rate of the closing timing of the intake valve estimated from a control amount of the variable valve mechanism at a calculation timing of the second injection amount, correcting the deviation based on the change rate, and calculating the second The fuel injection control device for an engine according to claim 6, wherein the injection amount is corrected.
According to the above-described invention, the change amount of the intake air amount from the calculation timing of the first injection amount to the closing timing of the intake valve is obtained, and the second injection amount is set based on the change amount.

DESCRIPTION OF SYMBOLS 101 ... Engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 112 ... Variable valve lift mechanism (VEL), 114 ... Variable valve timing mechanism (VTC), 115 ... Control unit (C / U), 116 ... Accelerator opening Sensor: 117 ... Air flow meter (AF / M), 118 ... Crank angle sensor, 119 ... Cam angle sensor, 120 ... Throttle sensor, 121 ... Port injection type fuel injection valve, 122 ... In-cylinder direct injection type fuel injection valve, 201 ... Actuator (DC servo motor), 206 ... Operating angle sensor

Claims (9)

In an engine that includes a direct injection type fuel injection valve that directly injects fuel into a cylinder, and a variable valve mechanism that varies the opening characteristics of the intake valve,
A first injection for injecting a first injection amount, and a second injection for injecting a second injection amount by the direct injection type fuel injection valve after the first injection and in the vicinity of the closing timing of the intake valve And
A fuel injection control device that corrects the second injection amount based on a change in an intake air amount generated by an operation of the variable valve mechanism after the calculation of the first injection amount;
The calculation timing of the second injection amount is set based on the closing timing of the intake valve based on the control amount of the variable valve mechanism at the calculation timing of the first injection amount,
The rate of change of the closing timing of the intake valve based on the control amount of the variable valve mechanism at the calculation timing of the second injection amount with respect to the closing timing, and the variable valve mechanism at the calculation timing of the first injection amount The second injection amount is set on the basis of a deviation between the intake air amount based on the control amount and the intake air amount based on the control amount of the variable valve mechanism at the calculation timing of the second injection amount. A fuel injection control device for an engine.   The closing timing of the intake valve is estimated from the control amount of the variable valve mechanism at the calculation timing of the first injection amount, and the timing delayed from the closing timing of the intake valve as the engine speed decreases is set to the second timing. 2. The engine according to claim 1, wherein the engine is set to an injection amount calculation timing, the second injection amount is calculated at the calculation timing, and the second injection for injecting the second injection amount is started. Fuel injection control device.   The first injection amount in the next first injection is corrected by a predetermined ratio of the fuel injection amount commensurate with the change in the intake air amount, and the corrected amount of the first injection is canceled out. The fuel injection control device for an engine according to claim 1 or 2, wherein the second injection amount is corrected.   The engine fuel injection according to any one of claims 1 to 3, wherein the first injection is performed by the in-cylinder direct injection fuel injection valve at an initial stage of an intake stroke after the exhaust valve is closed. Control device.   The basic value of the second injection amount is preset, and the second injection amount is determined by correcting the basic value based on a change in the intake air amount. The fuel injection control device for the engine described in 1.   The engine fuel injection control device according to claim 5, wherein the basic value of the second injection amount is determined in accordance with an operating state of the engine.   The engine fuel according to claim 5 or 6, wherein an amount obtained by subtracting a basic value of the second injection amount from a required injection amount of the engine at the calculation timing of the first injection amount is set as the first injection amount. Injection control device.   8. The engine fuel injection control device according to claim 1, wherein the second injection is not performed when it is not necessary to cope with a change in the intake air amount. .   The engine according to any one of claims 1 to 8, wherein correction of the fuel injection amount corresponding to the change in the intake air amount is limited in a state where a system abnormality of the variable valve system has occurred. Fuel injection control device.

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