JP2006118439A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent large deterioration of exhaust emission and startability at a time of start due to large drop of control accuracy of air fuel ratio at the time of start caused by response delay of a variable valve system. <P>SOLUTION: Determination timing of fuel injection quantity of a first time at start is determined based on a flag fSTINJEND. A target at the time of start is established to actual open characteristics vREVEL at the time to retain open characteristics during start after that if the open characteristics vREVEL of an intake valve does not reach a target vTGVELST at the time of start at the determination timing. Fuel injection quantity at the tim of start is corrected according to deviation between the retained open characteristics and the target at the time of start if open characteristics is retained to open characteristics before reaching the target at the time of start. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine that controls the intake air amount of the internal combustion engine by variably controlling the opening characteristics of the intake valve.

In Patent Document 1, a target torque is set from the accelerator opening and the engine rotational speed, and the opening characteristics of the intake valve and / or the opening of the throttle valve are set so that a target intake air amount corresponding to the target torque is obtained. An organization of varying structure is disclosed.
JP-A-6-272580

By the way, when the internal combustion engine is started at a very low temperature, a large response delay occurs in the operation of the variable valve mechanism that makes the opening characteristic of the intake valve variable because the friction of each part is large.
For this reason, when it is necessary to change the control position of the variable valve mechanism at the start of the engine from the control position of the variable valve mechanism when the internal combustion engine is stopped, by the timing of determining the initial fuel injection amount, The variable valve mechanism does not reach the target control position at the start, and after the initial fuel injection amount is determined until the first fuel injection is actually performed, the opening characteristics of the intake valve In some cases, it changed toward the goal.

At the time of start-up, the engine rotational speed fluctuates greatly, and since the intake air amount cannot be accurately detected immediately after the air flow meter is started, the injection amount at start-up has been conventionally determined based on the water temperature, engine speed, etc. Even when the intake air amount is controlled by the opening characteristic of the intake valve, the starting fuel injection amount is adapted to correspond to the expected intake air amount at the target opening characteristic at the time of starting.
Therefore, at the time of very low temperature start that does not reach the target open characteristic by the timing of determining the initial fuel injection amount, the fuel injection amount cannot be made to correspond to the actual open characteristic (intake air amount). There was a problem that the air-fuel ratio deviated greatly, and the exhaust properties and starting performance at the time of starting deteriorated.

  The present invention has been made in view of the above-mentioned problems, and it is possible to prevent the control accuracy of the air-fuel ratio from greatly decreasing at the start due to the response delay of the variable valve mechanism, and the exhaust properties and the start performance from starting to be greatly deteriorated. An object of the present invention is to provide a control device for an internal combustion engine.

  Therefore, according to the first aspect of the present invention, there is provided a control device for an internal combustion engine that includes a variable valve mechanism that varies the opening characteristic of the intake valve, and controls the intake air amount of the internal combustion engine by controlling the opening characteristic of the intake valve. When the response delay in which the opening characteristic of the intake valve reaches the target opening characteristic at the time of starting is larger than a predetermined value, the opening characteristic at the starting time is changed to a predetermined opening characteristic before reaching the target opening characteristic at the starting time. It was set as the structure made to hold | maintain.

According to this configuration, when the variable valve mechanism is controlled from the start to the target opening characteristic at the time of starting, if the response delay to reach the target opening characteristic at a very low temperature is large, the target opening The engine is started by maintaining the open characteristic before reaching the characteristic.
As described above, if the opening characteristic of the intake valve is kept constant during start-up when the response delay of the variable valve mechanism is large, it is avoided that the opening characteristic of the intake valve changes after the fuel injection amount is determined. It is possible to make the injection amount correspond to the actual intake air amount.

According to the second aspect of the present invention, when the opening characteristic of the intake valve does not reach the target opening characteristic at the time of starting at the timing of determining the initial fuel injection amount, the opening of the intake valve during the subsequent engine starting is started. The characteristic is maintained at the open characteristic at the timing for determining the initial fuel injection amount.
According to such a configuration, if the opening characteristic of the intake valve does not reach the target opening characteristic at the time of start from the start to the timing of determining the initial fuel injection amount, the intake valve is determined after the fuel injection amount is determined. The open characteristic of the fuel changes toward the target, and the open characteristic when the fuel injection amount is determined differs from the open characteristic when the fuel is actually injected.

Therefore, if the target opening characteristic has not been reached at the timing of determining the initial fuel injection amount at the start, the opening characteristic at the time is maintained and the actual opening characteristic when the fuel injection amount is determined and the actual fuel It matches the open characteristics when jetting.
Therefore, it is possible to avoid the change of the opening characteristic of the intake valve after the determination of the fuel injection amount while ensuring the maximum time for changing the opening characteristic of the intake valve toward the target, and to change the fuel injection amount to the actual intake air. It becomes possible to correspond to the amount.

According to a third aspect of the present invention, the fuel injection amount at the start is corrected in accordance with the held open characteristic.
According to this configuration, if the opening characteristic of the intake valve is maintained at the opening characteristic before reaching the target opening characteristic at the time of starting, the intake air amount is different from that when the target opening characteristic is controlled at the original starting time. Therefore, the fuel injection amount is corrected to an amount commensurate with the actual open characteristic.

  Therefore, even if there is a response delay of the variable valve mechanism, the control accuracy of the air-fuel ratio at the start can be ensured, and the exhaust properties and the start performance at the start can be improved.

Embodiments of the present invention will be described below.
FIG. 1 is a system configuration diagram of an internal combustion engine for a vehicle according to an embodiment.
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 the internal combustion engine 101, and a combustion chamber 106 is connected via the electronic control throttle 104 and the intake valve 105. Air is inhaled inside.

The combustion exhaust gas in the internal combustion engine 101 is discharged from the combustion chamber 106 through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The exhaust valve 107 is driven to open and close by a cam 111 pivotally supported on the exhaust camshaft 110 while maintaining a constant valve lift, valve operating angle, and valve timing.
On the other hand, on the intake valve 105 side, a variable valve event and lift (VEL) mechanism 112 that continuously varies the valve lift amount of the intake valve 105 together with the operating angle is provided.

Further, on the intake valve 105 side, a VTC (Variable Valve Timing Control) mechanism 113 that continuously varies the center phase of the valve operating angle of the intake valve 105 by changing the rotational phase of the intake camshaft with respect to the crankshaft. Is provided.
The VEL mechanism 112 and the VTC mechanism 113 correspond to the variable valve mechanism in the present embodiment.

An engine control unit (ECU) 114 incorporating a microcomputer controls the electronic control throttle 104, the VEL mechanism 112, and the VTC mechanism 113 based on the target intake air amount and the target intake negative pressure.
The ECU 114 includes an air flow meter 115 that detects the intake air amount of the internal combustion engine 101, an accelerator pedal sensor 116 that detects the accelerator opening, a crank angle sensor 117 that outputs a crank angle signal for each reference rotational position of the crankshaft 120, A throttle sensor 118 that detects the opening TVO of the throttle valve 103b, a water temperature sensor 119 that detects the coolant temperature of the internal combustion engine 101, a cam sensor 132 that outputs a cam signal for each reference rotational position of the camshaft 13, an intake manifold pressure (intake A detection signal from an intake pressure sensor 133 that detects (atmospheric pressure) is input.

Further, an electromagnetic fuel injection valve 131 is provided in the intake port 130 upstream of the intake valve 105 of each cylinder. The fuel injection valve 131 is driven to open by the injection pulse signal from the ECU 114, and the injection is performed. An amount of fuel proportional to the injection pulse width (valve opening time) of the pulse signal is injected.
2 to 4 show the structure of the VEL mechanism 112 in detail.

  The VEL mechanism 112 shown in FIGS. 2 to 4 includes a pair of intake valves 105, 105, a hollow camshaft 13 (drive shaft) rotatably supported by the cam bearing 14 of the cylinder head 11, and the camshaft Two eccentric cams 15 and 15 (drive cams), which are rotational cams supported by the shaft 13, a control shaft 16 rotatably supported by the same cam bearing 14 above the cam shaft 13, and the control shaft 16, a pair of rocker arms 18 and 18 supported by a control cam 17 so as to be swingable, and a pair of independent rockers disposed at upper ends of the intake valves 105 and 105 via valve lifters 19 and 19, respectively. The moving cams 20 and 20 are provided.

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.
The rocker arms 18, 18, the link arms 25, 25, and the link members 26, 26 constitute a transmission mechanism.

As shown in FIG. 5, 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 camshaft insertion hole 15 c is formed through the shaft, and the axis X of the cam body 15 a is eccentric from the axis Y of the camshaft 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 a cam shaft insertion hole 15c.

As shown in FIG. 4, 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.
A pin hole 18d into which a pin 21 connected to the tip end of the link arm 25 is press-fitted is formed at one end 18b protruding from the outer end of the base 18a, while the inner end of the base 18a is formed. 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 portion.

The control cam 17 has a cylindrical shape, is fixed to the outer periphery of the control shaft 16, and the position of the axis P1 is eccentric from the axis P2 of the control shaft 16 by α as shown in FIG.
As shown in FIGS. 2, 6, and 7, 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 through, and a pin hole 23a is formed through 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 toward the end edge side of the end portion 23 are formed on the lower surface of the swing cam 20. The circular surface 24 a and the cam surface 24 b come into contact with predetermined positions on the upper surfaces of the valve lifters 19 in accordance with the swing position of the swing cam 20.
That is, when viewed from the valve lift characteristics shown in FIG. 8, as shown in FIG. 2, the predetermined angle range θ1 of the base circle surface 24a becomes the base circle section, and the predetermined angle range θ2 from the base circle section θ1 of the cam surface 24b changes. This 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 of the eccentric cam 15 is provided. A fitting hole 25c is formed in the outer peripheral surface of 15a 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.
Further, the link member 26 is formed in a straight line having a predetermined length, and circular pin ends 26a and 26b have pin holes 18d in the other end 18c of the rocker arm 18 and the end 23 of the swing cam 20, respectively. , 23a, and pin insertion holes 26c and 26d through which end portions of the pins 28 and 29 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.
In the above configuration, the valve lift amount changes as shown in FIGS. 6 and 7 depending on the positional relationship between the axis P2 of the control shaft 16 and the axis P1 of the control cam 17, and the control shaft 16 is rotated. By driving, the position of the axis P2 of the control shaft 16 with respect to the axis P1 of the control cam 17 is changed.

  The control shaft 16 is configured to be rotationally driven by a DC servo motor (actuator) 121 within a predetermined rotational angle range limited by a stopper with the configuration shown in FIG. Is changed by the actuator 121 so that the valve lift amount and the valve operating angle of the intake valve 105 continuously change within a variable range between the maximum valve lift amount and the minimum valve lift amount limited by the stopper. (See FIG. 9).

In FIG. 10, the DC servo motor 121 is arranged so that its rotation shaft is parallel to the control shaft 16, and a bevel gear 122 is pivotally supported at the tip of the rotation shaft.
On the other hand, a pair of stays 123a and 123b are fixed to the tip of the control shaft 16, and a nut 124 is swingably supported around an axis parallel to the control shaft 16 connecting the tips of the pair of stays 123a and 123b. The

A bevel gear 126 meshed with the bevel gear 122 is pivotally supported at the tip of the screw rod 125 meshed with the nut 124, and the screw rod 125 is rotated by the rotation of the DC servo motor 121. The position of the nut 124 that meshes with the 125 is displaced in the axial direction of the screw rod 125 so that the control shaft 16 is rotated.
Here, the direction in which the position of the nut 124 is brought closer to the bevel gear 126 is a direction in which the valve lift amount is reduced, and conversely, the direction in which the position of the nut 124 is moved away from the bevel gear 126 is a direction in which the valve lift amount is increased. ing.

As shown in FIG. 10, a potentiometer type angle sensor 127 for detecting the angle of the control shaft 16 is provided at the tip of the control shaft 16, and the actual angle detected by the angle sensor 127 is the target angle. The ECU 114 feedback-controls the DC servo motor 121 so as to match (a target valve lift amount equivalent value).
In addition, the stopper member 128 protruding from the outer periphery of the control shaft 16 abuts on a receiving member (not shown) on the fixed side in both the increasing direction and decreasing direction of the valve lift, thereby rotating the control shaft 16. The range is regulated so that the minimum valve lift amount and the maximum valve lift amount are defined.

Next, the configuration of the VTC mechanism 113 will be described with reference to FIG.
The VTC mechanism 113 in the present embodiment is a vane type variable valve timing mechanism, and is connected to a cam sprocket 51 (timing sprocket) rotated by a crankshaft 120 via a timing chain and an end portion of the intake camshaft 13. A rotating member 53 that is fixed and rotatably accommodated in the cam sprocket 51, a hydraulic circuit 54 that rotates the rotating member 53 relative to the cam sprocket 51, and a relative relationship between the cam sprocket 51 and the rotating member 53. And a lock mechanism 60 that selectively locks the rotational position 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 with openings at the front and rear ends, and has a trapezoidal shape in cross section on the inner peripheral surface, and four partition walls 63 provided along the axial direction of the housing 56 are spaced by 90 °. It is projecting at.

The rotating member 53 is fixed to the front end portion of the intake side camshaft 14, and four vanes 78 a, 78 b, 78 c, 78 d 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 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 ECU 114 controls the energization amount for the electromagnetic actuator 99 that drives the electromagnetic switching valve 95 based on a duty control signal on which a dither signal is superimposed.
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 opening period (opening timing and closing timing) of the intake valve 105 is delayed.
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, and thereby the opening period (opening timing and closing timing) of the intake valve 105 is advanced.
It is obvious that the configuration of the variable valve mechanism is not limited to the VEL mechanism 112 and the VTC mechanism 113 configured as described above.
The ECU 114 controls the intake air amount while generating the negative pressure by the intake throttle by the electronic control throttle 104 when the generation of the intake negative pressure is required. However, under the condition that the generation of the intake negative pressure is not required, the ECU 114 The intake air amount is controlled by the mechanism 112 and the VTC mechanism 113.

Hereinafter, the intake air amount control by the VEL mechanism 112 and the VTC mechanism 113 will be described.
The block diagram of FIG. 12 shows a block for setting the target opening characteristic vTGVAL of the intake valve 105. As the target opening characteristic vTGVAL, a control target value vTGVEL (target angle of the control shaft 16) of the VEL mechanism 112 and The control target value vTGVTC of the VTC mechanism 113 is set.

In FIG. 12, the start time target setting unit S1100 inputs a flag fSTINJEND that rises at the timing of determining the initial fuel injection amount, the actual angle vREVEL of the control shaft 16, and the water temperature vTW, and opens the target opening for start. Calculates and outputs the characteristic vTGVALST.
On the other hand, the normal time target setting unit S1200 receives the engine speed vNRPM and the accelerator opening vAPO, and calculates and outputs a target open characteristic vTGVALO for normal time (after starting).

The starting target opening characteristic vTGVALST and the normal target opening characteristic vTGVALO are input to the switching unit S1300.
The switching unit S1300 outputs a target opening characteristic vTGVALST for starting or a target opening characteristic vTGVALO for starting time as a target opening characteristic vTGVAL based on a flag fSTSW indicating ON / OFF of a start switch Specifically, the target opening characteristic vTGVALST for starting is output at the time of starting (cranking) when the start switch is on, and the target opening characteristic for normal time is output during normal operation when the start switch is off. Output vTGVALO.

The target opening characteristic vTGVAL output from the switching unit S1300 is separated into the control target value vTGVEL of the VEL mechanism 112 and the control target value vTGVTC of the VTC mechanism 113, and used for feedback control of the VEL mechanism 112 and VTC mechanism 113, respectively. It is done.
The block diagram of FIG. 13 is a block diagram showing in detail the processing contents in the start time target setting unit S1100.

The starting VEL target setting unit S1101 calculates and outputs a starting VEL target value vTGVELST based on the water temperature vTW.
On the other hand, the starting VTC target setting unit S1108 calculates and outputs a starting VTC target value vTGVTCST based on the water temperature vTW.
The deviation calculation unit S1102 calculates a deviation ΔVEL between the actual angle vREVEL and the starting VEL target value vTGVELST, that is, a deviation ΔVEL between the actual angle of the control shaft 16 and the target angle.

In an absolute value calculation unit S1103, an absolute value of the deviation ΔVEL is obtained.
In the comparison unit S1105, it is determined whether or not the absolute value of the deviation ΔVEL is greater than or equal to the threshold value mERVLSLMT set in S1104.
The comparison unit S1105 outputs “1” when the absolute value of the deviation ΔVEL is greater than or equal to the threshold value mERVLSLMT, and outputs “0” otherwise.

The output of the comparison unit S1105 is input to the logical product calculation unit S1106 together with a flag fSTINJEND indicating the determination timing of the initial fuel injection amount.
The AND operation unit S1106 outputs “1” when the absolute value of the deviation ΔVEL is equal to or greater than the threshold value mERVLSLMT and is the determination timing of the initial fuel injection amount, and “0” otherwise. Is output.

  The output of the AND operation unit S1106 is input to the switching unit S1107 as a switching control signal, and the switching unit S1107 has the absolute value of the deviation ΔVEL greater than or equal to the threshold value mERVLSLMT and the determination timing of the initial fuel injection amount If it is, the actual angle vREVEL at that time is output as the starting VEL target value vTGVELST, and otherwise, the starting VEL target value vTGVELST set by the starting VEL target setting unit S1101 is output.

The output control unit S1109 outputs the start time VEL target value vTGVELST output from the switching unit S1107 together with the start time VTC target value vTGVTCST as the start time target open characteristic vTGVALST.
Until the flag fSTINJEND rises, that is, from the start (cranking) to the timing for determining the initial fuel injection amount, even if the absolute value of the deviation ΔVEL is greater than or equal to the threshold value mERVLSLMT, the VEL target setting at the start The start-time VEL target value vTGVELST set in part S1101 is output as a final target, and feedback control is performed so that the start-time VEL target value vTGVELST becomes this start-time VEL target value vTGVELST.

  On the other hand, if the absolute value of the deviation ΔVEL is greater than or equal to the threshold value mERVLSLMT when the flag fSTINJEND rises when the initial fuel injection amount is determined, the start VEL target value vTGVELST depends on the water temperature up to that point. By switching from the obtained value to the actual angle vREVEL at that time, feedback control is performed so that the actual angle vREVEL at that time is maintained during the subsequent cranking.

In addition, when the initial fuel injection amount is determined and the flag fSTINJEND rises, if the absolute value of the deviation ΔVEL is less than the threshold mERVLSLMT, the start VEL target value vTGVELST corresponding to the water temperature is completed. Will continue to be output.
The block diagram of FIG. 14 shows a fuel injection amount setting unit at the time of starting.
The basic injection amount setting unit S2001 calculates a basic injection amount at start-up based on the water temperature vTW, and the rotation correction coefficient setting unit S2002 calculates a rotation correction coefficient based on the engine speed vNRPM.

In the multiplication unit S2017, the basic injection amount is multiplied by a rotation correction coefficient, and the basic injection amount at the start is corrected according to the engine speed.
On the other hand, the comparison unit S2004 compares the engine rotation speed vNRPM with a threshold value (for example, 600 rpm) set in S2003, and outputs “1” when the engine rotation speed vNRPM exceeds the threshold value.
On the other hand, the flag fSTSW corresponding to the on / off of the start switch is inverted by the inversion processing unit S2205, and “1” is output from the inversion processing unit S2205 when the start switch is turned off.

The logical sum operation unit S2006 performs a logical sum operation between the output of the comparison unit S2004 and the output of the inversion processing unit S2205.
Accordingly, the OR operation unit S2006 outputs “1” when the engine rotational speed vNRPM is equal to or higher than the threshold value and / or when the start switch is turned off.
The timer unit S2007 starts timing when the output of the logical sum calculation unit S2006 rises to “1”, and outputs the timing result to the time correction coefficient setting unit S2008.

In the time correction coefficient setting unit S2008, a correction coefficient for reducing the starting injection amount according to the time after the engine speed vNRPM becomes equal to or higher than the threshold or the time after the start switch is turned off is set. Calculate and output.
In the multiplication unit S2017, the time correction coefficient is multiplied by the starting injection amount that has been corrected in accordance with the engine speed.

On the other hand, the deviation calculating unit S2009 calculates a deviation ΔVEL (ΔVEL = vTGVELSTO−vREVEL) between the starting VEL target value vTGVELSTO and the actual angle vREVEL based on the water temperature vTW.
The absolute value calculation unit S2011 calculates the absolute value of the deviation ΔVEL, and the comparison unit S2013 determines whether or not the absolute value of the deviation ΔVEL is greater than or equal to the threshold set in S2012.

The comparison unit S2013 outputs “1” as a switching control signal to the switching unit S2015 when the absolute value of the deviation ΔVEL is greater than or equal to a threshold value.
On the other hand, the injection amount correction coefficient setting unit S2010 calculates a correction coefficient for correcting the starting injection amount in accordance with the deviation ΔVEL.
Here, if the deviation ΔVEL is 0, 1.0 is set as the correction coefficient.

When the actual angle vREVEL is smaller than the starting VEL target value vTGVELSTO and the deviation ΔVEL is calculated as a positive value, the larger the deviation ΔVEL is, the smaller the correction coefficient is with respect to 1.0. Is set.
Further, when the actual angle vREVEL is larger than the starting VEL target value vTGVELSTO and the deviation ΔVEL is calculated as a negative value, the larger the deviation ΔVEL is, the larger the correction coefficient is with respect to 1.0. Is set.

In the present embodiment, the valve lift amount increases as the angle of the control shaft 16 increases. Therefore, when the actual angle vREVEL is smaller than the start VEL target value vTGVELSTO, the intake valve 105 It is determined that the lift amount is small and the intake air amount is less than the expected amount.
Therefore, when the deviation ΔVEL is calculated as a positive value, a correction coefficient smaller than 1.0 is set to correct the start-up injection amount so that the intake air amount is smaller than expected. The injection amount is corrected.

  The switching unit S2015 selects either the correction coefficient calculated in the injection amount correction coefficient setting unit S2010 or the reference value (= 1.0) set in S2014 according to the comparison result in the comparison unit S2013. If the absolute value of the deviation ΔVEL is greater than or equal to the threshold, the correction coefficient calculated by the injection amount correction coefficient setting unit S2010 is output. If the absolute value of the deviation ΔVEL is less than the threshold, the reference value ( = 1.0) is output so that the starting injection amount is not substantially corrected.

The correction coefficient output from the switching unit S2015 is multiplied by the starting injection amount after being corrected by the time correction coefficient in the multiplication unit S2018, and the multiplication result in the multiplication unit S2018 is the final start time. Output as injection quantity vTIST.
The starting injection amount is compared with the fuel injection amount calculated based on the detection result of the air flow meter 115 and the engine speed, and the fuel injection valve 131 performs fuel injection based on the larger fuel injection amount. .

The VEL mechanism 112 of the present embodiment needs to be changed to the target angle at the start when starting, since the angular position of the control shaft 16 when the engine is stopped is different from the angular position required at the start. At the time of starting, the response delay becomes large, and the time delay until the angle position suitable for starting is reached becomes large.
As a result, the target at the time of starting may not be reached even when the initial fuel injection amount is determined.

On the other hand, the fuel injection amount at the start that is set based on the water temperature or the like is matched on the assumption that the VEL mechanism 112 and the VTC mechanism 113 are controlled to the target at the start, so the VEL mechanism 112 is started. If the time target is not reached, the fuel injection amount at the start will not be suitable.
Furthermore, even if the fuel injection amount is corrected according to the actual angle vREVEL at the timing of determining the fuel injection amount, if the actual angle vREVEL changes toward the original target before the fuel is actually injected, The fuel injection amount at the start does not match the intake air amount in the cycle, resulting in an air-fuel ratio shift.

Therefore, in the present embodiment, when the VEL mechanism 112 has not reached the start target at the timing when the initial fuel injection amount is determined, the actual angle vREVEL at that time is subsequently held. In the above, the fuel injection amount at the start is corrected according to the deviation between the original start target and the held angle.
As a result, even when the VEL mechanism 112 has not reached the target at the time of starting by the timing of determining the initial fuel injection amount, the fuel is actually injected from the timing of determining the fuel injection amount. During this period, the valve lift does not change, and the fuel injection amount corresponding to the valve lift at that time is corrected. Therefore, the fuel injection amount can be adapted to the actual intake air amount, and the air-fuel ratio at the time of cold start It is possible to suppress the occurrence of deviation and improve the exhaust properties and starting performance at the time of starting.

In the above embodiment, the intake air amount is controlled exclusively by controlling the valve lift by the VEL mechanism 113. However, the intake air amount is controlled by controlling the valve timing (closing timing) of the intake valve. Also good.
Even in a configuration in which the intake air amount is controlled by controlling the valve timing (closing timing) of the intake valve, when the valve timing (closing timing) of the intake valve does not change to the target by the timing of determining the initial fuel injection amount The actual valve timing (close timing) at that time is set as a control target at the time of start so that the valve timing (close timing) is maintained. Further, the actual valve timing (close timing) The fuel injection amount may be corrected according to the deviation from the target at the start.

  In the above-described embodiment, the determination is made as to whether or not the VEL mechanism 113 has a response delay greater than or equal to a predetermined time at the determination timing of the initial fuel injection amount. For example, for a predetermined time from when the VEL mechanism 113 is started. After the elapse of time, after a predetermined crank angle rotation from the start (cranking) start, it is possible to determine the response delay by comparing the actual angle vREVEL with the target at the start.

However, if the response delay determination timing is later than the initial fuel injection amount determination timing, the initial fuel injection amount will not match the actual intake air amount, and if the response delay determination timing is too early. Since the difference between the original target opening characteristic and the maintained opening characteristic becomes large, it is preferable to make a determination at the timing of determining the initial fuel injection amount.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof.
(A) In the control apparatus for an internal combustion engine according to claim 2,
The variable valve mechanism is feedback-controlled based on the deviation between the actual value and the target value of the opening characteristic of the intake valve, and the opening characteristic of the intake valve is determined at the timing for determining the initial fuel injection amount. When the target opening characteristic at the time of starting is not reached, the opening characteristic of the intake valve at that time is set to the target opening characteristic at the time of starting, so that the opening characteristic at the timing for determining the initial fuel injection amount of the engine start A control apparatus for an internal combustion engine, characterized by being held in

According to such a configuration, if the actual open characteristic at the timing of determining the initial fuel injection amount of the engine is set as the target in feedback control during start-up, feedback control is performed so as to maintain the actual open characteristic at the timing. Will be.
(B) In the control device for an internal combustion engine according to any one of claims 1 to 3,
A control apparatus for an internal combustion engine, characterized in that a state in which a start switch is on is determined as starting the engine.

According to this configuration, when the response delay in which the opening characteristic of the intake valve reaches the target opening characteristic at the start is greater than a predetermined value, the target of the opening characteristic of the intake valve is The predetermined open characteristic before reaching the target open characteristic is maintained.
(C) The control apparatus for an internal combustion engine according to claim 3, wherein the fuel injection amount is corrected in accordance with a deviation between the held open characteristic and the target open characteristic at the time of start.

According to such a configuration, the fuel injection amount is corrected in accordance with the deviation between the opening characteristic of the intake valve and the target opening characteristic at the start, so that it is set in accordance with the expected intake air amount at the original target opening characteristic. The fuel injection amount can be corrected to an amount commensurate with the expected intake air amount in actual open characteristics.
Therefore, when the open characteristic of the intake valve is maintained, the fuel injection amount can be accurately corrected to an amount commensurate with the actual open characteristic (intake air amount).

1 is a system configuration diagram of an internal combustion engine in an embodiment. Sectional drawing (AA sectional drawing of FIG. 3) which shows a VEL (Variable valve Event and Lift) mechanism. The side view of the said VEL mechanism. The top view of the said VEL mechanism. The perspective view which shows the eccentric cam used for the said VEL mechanism. Sectional drawing which shows the effect | action at the time of the low lift of the said VEL mechanism (BB sectional drawing of FIG. 3). Sectional drawing which shows the effect | action at the time of the high lift of the said VEL mechanism (BB sectional drawing of FIG. 3). The valve lift characteristic view corresponding to the base end surface and cam surface of the swing cam in the VEL mechanism. FIG. 6 is a characteristic diagram of valve timing and valve lift of the VEL mechanism. The perspective view which shows the rotational drive mechanism of the control shaft in the said VEL mechanism. The longitudinal cross-sectional view which shows a VTC (Variable valve Timing Control) mechanism. The block diagram which shows the setting process of the target opening characteristic of the intake valve in embodiment. The block diagram which shows the setting process of the target opening characteristic for the time of starting of the intake valve in embodiment. The block diagram which shows the setting process of the fuel injection amount for the start time in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 13 ... Cam shaft, 16 ... Control shaft, 99 ... Electromagnetic actuator, 101 ... Internal combustion engine, 104 ... Electronically controlled throttle, 105 ... Intake valve, 112 ... VEL mechanism, 113 ... VTC mechanism, 114 ... Engine control unit (ECU), 117 ... Crank angle sensor, 120 ... Crank shaft, 121 ... DC servo motor, 132 ... Cam sensor

Claims (3)

In a control device for an internal combustion engine, comprising a variable valve mechanism that varies an opening characteristic of the intake valve, and controlling an intake air amount of the internal combustion engine by controlling the opening characteristic of the intake valve.
When the response delay in which the opening characteristic of the intake valve reaches the target opening characteristic at the time of starting is larger than a predetermined value, the opening characteristic at the time of starting is maintained at the predetermined opening characteristic before reaching the target opening characteristic at the time of starting A control device for an internal combustion engine, characterized by comprising:   When the opening characteristic of the intake valve does not reach the target opening characteristic at the time of starting at the timing of determining the initial fuel injection amount, the opening characteristic of the intake valve during the subsequent engine start is 2. The control apparatus for an internal combustion engine according to claim 1, wherein an open characteristic at a timing for determining the fuel injection amount is maintained.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection amount at the start is corrected in accordance with the held open characteristic.

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