JP2003035169A - Control device for in-cylinder injection internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a control device for an in-cylinder injection type internal combustion engine that can suppress a starting failure at the time of restart or the like. A valve timing of an intake valve of an engine is made variable by hydraulically controlling a variable valve timing mechanism. When it is determined that the variable valve timing mechanism 25 has not returned to the position (reference position) where the valve timing of the intake valve 20 is the most retarded at the start of the engine 1, the fuel during the engine start and immediately after the completion of the engine start is determined. The injection amount is reduced. For this reason,
Even if the variable valve timing mechanism 25 has not returned to the reference position, and the internal EGR amount becomes excessive due to the fuel combustion in this state and oxygen shortage occurs, the air-fuel ratio becomes excessively rich with it. Be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a cylinder injection type internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as an internal combustion engine for an automobile, for example, an in-cylinder injection type that directly injects fuel into a combustion chamber is known.

When the internal combustion engine is cold-started, the fuel injected into the combustion chamber is less likely to be atomized and is likely to remain as a liquid fuel. Therefore, the fuel is burned in the presence of the liquid fuel in the combustion chamber. Sometimes. In this case, the liquid fuel in the combustion chamber burns due to the heat of combustion,
The exhaust from the internal combustion engine may contain black smoke.

Therefore, for example, Japanese Patent Laid-Open No. 11-324778.
As disclosed in the publication, the exhaust gas of the internal combustion engine is made to exist in the combustion chamber during fuel combustion, thereby lowering the combustion temperature during fuel combustion and suppressing the burning of liquid fuel, and the heat of the exhaust gas causes combustion chamber combustion. It is also conceivable to raise the temperature of the fuel to accelerate atomization of the liquid fuel. In this way, it is possible to suppress the occurrence of black smoke by suppressing the burning of the liquid fuel in the combustion chamber and promoting the atomization of the fuel.

As a method of allowing the exhaust gas of the internal combustion engine to exist in the combustion chamber during fuel combustion, the valve timing variable mechanism for varying the valve timing of the intake valve in the engine is hydraulically controlled to control the valve timing of the intake valve. There is a method of performing advance control for advancing from the most retarded state. That is, when the valve timing of the intake valve is advanced from the most retarded state by the advance control as described above, the valve overlap between the intake valve and the exhaust valve increases as the advance amount increases, and the fuel combustion increases. A large amount of exhaust gas generated during the previous combustion of fuel will remain in the combustion chamber at that time.

[0006]

By the way, in the process of stopping the internal combustion engine, the hydraulic pressure of the hydraulic oil for operating the variable valve timing mechanism decreases, and a reaction force associated with the opening / closing drive of the intake valve acts on the mechanism. Therefore, the variable valve timing mechanism operates to retard the valve timing of the intake valve to the most retarded state.

However, in the case where the above-mentioned advance control is started at the time of cold start of the internal combustion engine and then the engine is stopped and restarted, the intake valve is started before the restart is started. There is a risk that the valve timing of will not be fully returned to the most retarded state.

The causes of this are as follows: The internal combustion engine was stopped before the hydraulic oil for operating the variable valve timing mechanism was warmed by the engine operation and became low in viscosity, so the variable valve timing was set before the restart was started. The mechanism does not return to the position where the intake valve is in the most retarded state (reference position) .- A hydraulic oil with a viscosity higher than that suitable for operating the valve timing variable mechanism is used. Therefore, it is possible that the variable valve timing mechanism does not completely return to the reference position before the restart is started.

When the valve timing of the intake valve has not fully returned to the most retarded state by the time of the restart, the amount of exhaust gas existing in the gas in the combustion chamber at the time of the restart is excessively large. Become. As a result, the oxygen in the combustion chamber is insufficient for obtaining good fuel combustion, and the air-fuel ratio becomes excessively rich, which may cause a start failure of the internal combustion engine.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a control apparatus for a cylinder injection type internal combustion engine capable of suppressing a start failure such as at the time of restart. It is in.

[0011]

[Means for Solving the Problems] Means for achieving the above-mentioned objects and their effects will be described below. In order to achieve the above object, the invention according to claim 1 is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting an amount of exhaust gas contained in a gas in a combustion chamber at the time of fuel combustion. In the control device for a cylinder injection internal combustion engine, which executes the exhaust amount increase control for operating the adjusting means from the predetermined position to the side for increasing the exhaust amount in the gas by hydraulic pressure at the time of starting, at the time of starting the internal combustion engine, A correction unit is provided to correct the fuel injection amount from engine start-up based on the operation amount of the adjustment unit from the predetermined position to increase the exhaust amount in the gas.

At the time of starting the internal combustion engine, if the adjusting means does not return to the predetermined position from the side where the amount of exhaust gas contained in the gas in the combustion chamber during fuel combustion is increased, the amount of exhaust gas in the gas is appropriate. More than the value. Therefore, oxygen in the combustion chamber is insufficient for obtaining good fuel combustion,
The air-fuel ratio of the internal combustion engine becomes excessively rich. However, according to the above configuration, when the internal combustion engine is started, the fuel injection amount is reduced and corrected based on the operation amount from the predetermined position in the adjusting means to the side that increases the exhaust amount contained in the gas. It is possible to prevent the start-up failure from occurring due to the air-fuel ratio becoming excessively rich due to the excessive displacement.

The operation amount for increasing the exhaust amount of the gas from the predetermined position in the adjusting means is determined in the process of stopping the internal combustion engine or in the process of starting the internal combustion engine. Can be adopted.
Further, regarding the reduction correction of the fuel injection amount from the engine start, it is preferable to increase the reduction correction amount as the above-mentioned operation amount increases.

According to the second aspect of the invention, the invention is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and at the time of cold starting of the engine. In a control device for a cylinder injection internal combustion engine, which executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side that increases an exhaust gas amount in the gas,
When starting the internal combustion engine, when it is determined that the adjusting unit has not returned to the vicinity of the predetermined position from the side that increases the exhaust amount in the gas, a correction unit that reduces the fuel injection amount from the start of the engine start Equipped with.

When the internal combustion engine is started, the air-fuel ratio becomes excessively rich due to the execution of the exhaust gas increase control when the adjusting means has not returned to the predetermined position. This is suppressed by the decrease correction of the fuel injection amount. Therefore, the starting failure due to the rich air-fuel ratio is suppressed.

According to the invention of claim 3, claim 1 or 2
In the invention described above, the correction means starts the reduction correction of the fuel injection amount on condition that the fuel combustion is performed after the start of the internal combustion engine.

Since the exhaust gas does not exist in the combustion chamber at the time of the first fuel combustion, it is unlikely that the air-fuel ratio becomes excessively rich due to the lack of oxygen due to the excessive exhaust gas amount. According to the above configuration, the reduction of the fuel injection amount that is not necessary in the first fuel injection after the start of the start is performed, and thus it is possible to prevent the fuel injection amount from becoming insufficient and leading to a start failure.

According to a fourth aspect of the invention, in the third aspect of the invention, the correction means is provided on condition that the first fuel combustion is performed in all the cylinders of the internal combustion engine after the start of the internal combustion engine. The reduction correction of the fuel injection amount is started.

According to the above construction, the unnecessary fuel injection amount is reduced in the first fuel injection after the start of the start in each cylinder, thereby preventing the fuel injection amount from becoming insufficient and leading to a start failure. be able to.

In the invention according to claim 5, in the invention according to any one of claims 1 to 4, the initial value of the reduction correction amount of the fuel injection amount is in the gas from a predetermined position in the adjusting means. It is supposed to be variable based on the operating amount to the side that increases the displacement.

Since the amount of exhaust gas existing in the gas in the combustion chamber at the time of fuel combustion changes based on the operation amount of the adjusting means, the initial value of the reduction correction amount of the fuel injection amount can be changed according to the operation amount. By doing so, the weight reduction correction can be appropriately performed.

It should be noted that the initial value of the reduction correction amount of the fuel injection amount is preferably increased as the above-mentioned operation amount is increased. In the invention of claim 6, claims 1 to 5
In any one of the above aspects, the initial value of the reduction correction amount of the fuel injection amount is variable based on the piston temperature.

The amount of fuel adhering to the inner wall surface of the combustion chamber, which affects the air-fuel ratio of the internal combustion engine, and the amount of vaporization of the adhering fuel change depending on the piston temperature. By making the initial value of the amount reduction correction variable, the amount reduction correction can be appropriately performed.

It should be noted that the piston temperature is estimated based on the operation execution time in the engine operation immediately before starting, or based on the integrated intake air amount and the integrated fuel injection amount during execution of the engine operation. It is possible to do it. Furthermore, in estimating the piston temperature, the engine stop time from the last engine operation to the present engine start may be taken into consideration.

In the invention of claim 7, claim 5 or 6
In the invention described above, the reduction correction amount of the fuel injection amount is
The initial value was gradually decreased with the lapse of time.

According to the above configuration, it is possible to prevent a problem such as a torque shock from occurring due to the reduction correction amount of the fuel injection amount suddenly becoming "0". According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the correction unit is configured to perform the fuel injection when the internal combustion engine has not been started for a predetermined time after the start of the internal combustion engine. It was decided to stop the amount reduction correction.

If the amount of correction of the fuel injection amount at the time of starting is excessively corrected, it becomes difficult to start the internal combustion engine. However, according to the above configuration, the reduction correction of the fuel injection amount is stopped when the internal combustion engine is difficult to start, so that it is possible to prevent the startability of the internal combustion engine from being deteriorated by the reduction correction of the excessive fuel injection amount. it can.

According to a ninth aspect of the invention, the invention is applied to a cylinder injection internal combustion engine equipped with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion. In a control device for a cylinder injection internal combustion engine, which executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side that increases an exhaust gas amount in the gas,
At the time of starting the internal combustion engine, when the operation amount of the adjusting means from the predetermined position to increase the exhaust amount in the gas is larger than a predetermined value, the adjusting means is controlled to the predetermined position side. It is equipped with a control means.

At the time of starting the internal combustion engine, when the adjusting means does not return to the predetermined position from the side where the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion is increased, the amount of exhaust gas in the gas is appropriate. More than the value. Therefore, oxygen in the combustion chamber is insufficient for obtaining good fuel combustion,
The air-fuel ratio of the internal combustion engine becomes excessively rich. However, according to the above configuration, the adjusting means is controlled to the predetermined position side in such a situation, and the exhaust amount in the gas is reduced, so that the air-fuel ratio becomes excessively rich due to the excessive exhaust amount. Therefore, it is possible to suppress the occurrence of poor starting.

According to the tenth aspect of the invention, the invention is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion. In a control device for a direct injection internal combustion engine that executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side that increases the exhaust gas amount in the gas by hydraulic pressure, when the internal combustion engine is started, the adjusting means is A control means is provided for controlling the adjusting means to the predetermined position side when it is determined that the amount of exhaust gas in the gas has not returned to the vicinity of the predetermined position.

When the internal combustion engine is started, the air-fuel ratio becomes excessively rich due to the execution of the exhaust gas increase control when the adjusting means has not returned to the predetermined position. As a result, the start failure due to the rich air-fuel ratio is suppressed.

In the invention according to claim 11, in the invention according to claim 9 or 10, when the control means controls the adjusting means to the predetermined position side when the internal combustion engine is started, the adjusting means is The fuel injection is stopped until it returns to a predetermined operating position on the predetermined position side.

According to the above construction, the fuel injection is temporarily stopped and the scavenging of the combustion chamber is performed, so that the fuel is not burned in the state where a large amount of exhaust gas exists in the combustion chamber. Therefore, it is possible to properly prevent the exhaust amount in the gas existing in the combustion chamber at the time of fuel combustion from becoming excessively large, and the air-fuel ratio becoming excessively rich accordingly, leading to a start failure.

According to a twelfth aspect of the invention, in the invention of the second or tenth aspect, it is determined that the adjusting means has not returned to the vicinity of the predetermined position in the gas from the predetermined position in the adjusting means. It is assumed that the operation amount to the side that increases the exhaust amount is greater than a predetermined value.

With the above arrangement, it is possible to accurately determine that the adjusting means has not returned to the vicinity of the predetermined position when the internal combustion engine is started, based on the operation amount.
It should be noted that as the operation amount for increasing the exhaust amount in the gas from the predetermined position in the adjusting means, one that is obtained in the process of stopping the internal combustion engine or one that is obtained in the process of starting the internal combustion engine is adopted. be able to.

According to the thirteenth aspect of the present invention, in the second or tenth aspect of the invention, it is determined that the adjusting means has not returned to the vicinity of the predetermined position, and the operating oil used for hydraulic control of the adjusting means is determined. It was decided to be based on the assumption that the viscosity is high.

According to the above construction, it is possible to accurately judge that the adjusting means has not returned to the vicinity of the predetermined position when the internal combustion engine is started, based on the estimated viscosity of the hydraulic oil.

The estimation of whether or not the viscosity of the hydraulic oil is high is made based on whether or not the engine operating time since the exhaust amount increase control in the previous engine operation was performed is shorter than a predetermined time. It is possible that

According to the fourteenth aspect of the present invention, the invention is applied to a cylinder injection internal combustion engine equipped with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion. In a control device for a direct injection internal combustion engine that executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side where the amount of exhaust gas in the gas is increased, the exhaust gas increase control is performed at least when the internal combustion engine is started. When the engine is stopped after execution of the above, the stop that stops the internal combustion engine is performed on the condition that the adjustment unit returns to the vicinity of a predetermined position from the side that increases the exhaust amount in the gas. Equipped with means.

According to the above construction, since the internal combustion engine is stopped after the adjusting means returns to the vicinity of the predetermined position in the engine stop process, there is a situation in which the adjusting means does not return to the vicinity of the predetermined position when the internal combustion engine is started. What happens is avoided. Therefore, at the time of engine startup, it is possible to prevent the start-up failure of the internal combustion engine due to insufficient oxygen in the combustion chamber and excessive enrichment of the air-fuel ratio due to fuel injection being performed under these circumstances. it can.

According to a fifteenth aspect of the invention, the invention is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and when the engine is cold started. In a control device for a direct injection internal combustion engine that executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side where the amount of exhaust gas in the gas is increased by hydraulic pressure, the operation of the adjusting means is evaluated during the low temperature start. However, when it is determined that the operation of the adjusting means is slow, a stop means for stopping the exhaust gas increase control at the low temperature start is provided.

According to the above arrangement, when there is a possibility that the operation of the adjusting means is slow and the adjusting means is not fully returned to the vicinity of the predetermined position when the internal combustion engine is started, the exhaust gas increase control is stopped and the above-mentioned control is stopped. The situation like this will not occur. Therefore, at the time of engine start, it is possible to suppress the occurrence of a start failure of the internal combustion engine due to insufficient oxygen in the combustion chamber and excessively rich air-fuel ratio due to the fuel injection being executed under such circumstances. it can.

Regarding the judgment as to whether or not the operation of the adjusting means is slow, for example, the operation of the adjusting means when a predetermined time elapses after the adjusting means is controlled to the side that increases the exhaust amount in the gas It can be done based on quantity.

According to the sixteenth aspect of the invention, the invention is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and when the engine is cold started. In a control device for a direct injection internal combustion engine that executes an exhaust gas increase control for operating the adjusting means from a predetermined position to a side that increases the exhaust gas amount in the gas by a hydraulic pressure, a stop process and a start process of the internal combustion engine The heating means for heating the hydraulic oil for operating the adjusting means is provided during a predetermined period in at least one of the two.

According to the above construction, the viscosity of the hydraulic oil is lowered by heating the hydraulic oil for operating the adjusting means. It is possible to prevent a situation in which the vehicle has not completely returned to the vicinity of the predetermined position. Therefore, at the time of starting the engine, the exhaust gas increase control and the fuel injection are executed under such a situation, so that the oxygen in the combustion chamber becomes insufficient and the air-fuel ratio becomes excessively rich, which causes a start failure of the internal combustion engine. Can be suppressed.

In the exhaust amount increase control according to the invention described in claims 1 to 16, the adjusting means is operated from the reference position where the exhaust amount in the gas is the minimum to the side where the exhaust amount is increased. It is possible to Further, the adjusting means operates so as to change the valve timing of the intake valve of the internal combustion engine, and when the exhaust amount increase control is performed, the adjusting means is operated from the reference position where the intake valve is in the most retarded state. It is considered that the intake valve is operated to advance the valve timing.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which the present invention is applied to an in-cylinder injection spark ignition type multi-cylinder engine for an automobile will be described below with reference to FIGS.

In the engine 1 shown in FIG. 1, with respect to the air-fuel mixture composed of the air sucked from the intake passage 2 into the combustion chamber 3 and the fuel injected and supplied from the fuel injection valve 4 into the combustion chamber 3. Then, the ignition by the spark plug 5 is performed. The ignition timing of the spark plug 5 is adjusted by the igniter 5a. When the air-fuel mixture in the combustion chamber 3 is burned by this ignition, the piston 6 reciprocates due to the combustion energy at that time, and the air-fuel mixture after combustion is sent to the exhaust passage 7 as exhaust gas.

Further, the reciprocating movement of the piston 6 is converted into rotation of the crankshaft 9 which is the output shaft of the engine 1 by the connecting rod 8. Then, when the crankshaft 9 rotates, a signal corresponding to the rotation is output from the crank position sensor 10. Also,
When the engine 1 is driven as described above, the engine 1 is cooled by the cooling water, and the temperature of the cooling water is detected by the water temperature sensor 36.

A throttle valve 11 that opens and closes to adjust the amount of air sucked into the combustion chamber 3 (intake air amount) is provided in the upstream portion of the intake passage 2, and downstream from the throttle valve 11. A vacuum sensor 12 for detecting the pressure in the intake passage 2 (intake pressure) is provided. The opening degree of the throttle valve 11 (throttle opening degree) is adjusted according to the depression amount of the accelerator pedal 13 (accelerator depression amount) operated by the driver of the vehicle. The accelerator depression amount is detected by the accelerator position sensor 14, and the throttle opening amount is detected by the throttle position sensor 15.

In the engine 1, the intake passage 2 and the combustion chamber 3 are connected / disconnected by the opening / closing operation of the intake valve 20, and the exhaust valve 21 is provided between the exhaust passage 7 and the combustion chamber 3.
It is connected and disconnected by opening and closing. Then, the intake valve 20 and the exhaust valve 21 are opened and closed with the rotation of the intake camshaft 22 and the exhaust camshaft 23 to which the rotation of the crankshaft 9 is transmitted. A cam position sensor 24 for detecting the rotational position of the intake camshaft 22 is provided near the intake camshaft 22.

The intake camshaft 22 has a variable valve timing mechanism 25 for changing the valve timing (opening / closing timing) of the intake valve 20 by changing the relative rotation phase of the intake camshaft 22 with respect to the rotation of the crankshaft 9. Is provided. An advance side oil passage 26 and a retard side oil passage 27 are connected to the variable valve timing mechanism 25. And these oil passages 26 and 27
Is connected to an oil pan 31 of the engine 1 via an oil control valve (OCV) 28, and a supply passage 29 and a discharge passage 30.

The supply passage 29 is provided with an oil pump 32 which is driven by the rotation of the crankshaft 9. Further, the OCV 28 is switched by the biasing forces of the coil spring 33 and the electromagnetic solenoid 34 acting in opposite directions, and the supply passage 29 and the discharge passage 30 are connected to the advance side oil passage 26 and the retard side oil passage 27. Change the state.

That is, the OCV 28 has an electromagnetic solenoid 34.
In the demagnetized state, the retard side oil passage 27 and the supply passage 29
And the advance side oil passage 26 and the discharge passage 30.
Communicate with. In this case, the oil (working oil) in the oil pan 31 is sent to the retard side oil passage 27 by the oil pump 32, and the oil (working oil) in the advance side oil passage 26 enters the oil pan 31. Will be returned. At this time, the variable valve timing mechanism 25 includes the retard side oil passage 27.
Oil is supplied through. As a result, the variable valve timing mechanism 25 is hydraulically operated to retard the relative rotation phase of the intake camshaft 22 with respect to the crankshaft 9. As a result, the valve timing of the intake valve 20 changes to the retard side.

When the electromagnetic solenoid 34 is excited, the retard side oil passage 27 communicates with the discharge passage 30 and the advance side oil passage 26 communicates with the supply passage 29.
In this case, the oil in the oil pan 31 is the oil pump 3
2 is sent to the advance side oil passage 26, and the oil in the retard side oil passage 27 is returned to the oil pan 31. At this time, oil is supplied to the variable valve timing mechanism 25 through the advance side oil passage 26. As a result, the variable valve timing mechanism 25 is hydraulically operated to advance the relative rotational phase of the intake camshaft 22 with respect to the crankshaft 9. As a result, the valve timing of the intake valve 20 changes to the advance side.

Next, the electrical construction of the engine control system of this embodiment will be described. This control device is an electronic control device 3 mounted on an automobile to control the operation of the engine 1.
It is equipped with 5.

This electronic control unit 35 includes an igniter 5
a, the fuel injection valve 4, the OCV 28 and the like are drive-controlled.
Further, the electronic control unit 35 receives detection signals from various sensors such as a crank position sensor 10, a vacuum sensor 12, an accelerator position sensor 14, a throttle position sensor 15, a cam position sensor 24, and a water temperature sensor 36. Further, the electronic control unit 35 is a RAM that is a memory that temporarily stores data and the like input from the various sensors, and a backup that is a non-volatile memory that stores data to be stored when the engine 1 is stopped. It has a RAM and the like.

The electronic control unit 35, based on the detection signals from the crank position sensor 10, the throttle position sensor 15, the vacuum sensor 12, and the accelerator position sensor 14, the engine speed NE, the intake pressure PM, the accelerator depression amount ACCP, and the throttle. The opening degree TA is obtained. Then, the electronic control unit 35 sets the load factor KL, which is a value indicating the current load ratio with respect to the maximum engine load, to the engine speed NE, the throttle opening TA, the accelerator depression amount ACCP, the intake pressure PM, and the like of the engine 1. It is calculated based on the parameters related to the intake air amount.

The electronic control unit 35 controls the engine speed N
Ignition timing control, fuel injection amount control, and intake valve 2 according to the operating state of the engine 1 such as E and load factor KL.
Various operation controls of the engine 1 such as zero valve timing control are executed.

Next, a procedure for suppressing the generation of black smoke when the engine is in a state where the exhaust gas contains black smoke, such as when the engine 1 is started at a low temperature, will be described with reference to FIG. Figure 2
By controlling the valve timing of the intake valve 20, the amount of exhaust gas contained in the gas in the combustion chamber 3 during fuel combustion (internal EGR
6 is a flowchart showing a black smoke suppressing routine for adjusting the amount) to suppress the generation of the black smoke. This black smoke suppression routine is periodically executed by the electronic control unit 35, for example, by an angle interruption at every predetermined crank angle.

In the black smoke suppression routine, the engine 1
If the start of the combustion chamber 3 is started (S101: YES).
An estimated temperature T, which is a value obtained by estimating the temperature of, is calculated (S102).

The actual temperature of the combustion chamber 3 rises for each combustion cycle of the engine 1 by an amount corresponding to the amount of fuel consumed in the combustion cycle. This fuel amount becomes a value corresponding to the command value of the fuel injection amount used when the fuel injection amount control of the engine 1 is performed, that is, the final fuel injection amount Qfin obtained from the load factor KL and the engine rotation speed NE.

Therefore, in the process of step S102, the temperature rise amount of the combustion chamber 3 in the present combustion cycle is calculated by multiplying the final fuel injection amount Qfin by the conversion coefficient K, and the value "Qfin.K" is calculated. The previous S10
The estimated temperature T of this time is calculated by adding to the estimated temperature T calculated in the process of 2. In addition,
The conversion coefficient K is the amount of fuel consumed (combusted) in one combustion cycle of the engine 1 (final fuel injection amount Qfin).
Is converted into a unit of the temperature rise amount of the combustion chamber 3 due to the combustion.

When the process of step S102 is first executed after the start of the engine 1, the initial temperature calculated from the cooling water temperature of the engine 1 is used as the previous estimated temperature T used to calculate the estimated temperature T. Adopted.
The initial temperature is calculated to have a higher value as the cooling water temperature of the engine 1 obtained from the detection signal of the water temperature sensor 36 becomes higher.

After the estimated temperature of the combustion chamber 3 is calculated in this manner, it is determined whether the estimated temperature T is less than or equal to a predetermined value a2 which is a temperature range in which black smoke may occur (S10).
3). Then, if the determination is affirmative, it is determined that it is a situation in which the generation of black smoke should be suppressed by the exhaust gas contained in the gas in the combustion chamber 3 at the time of fuel combustion, and the advance control of the valve timing of the intake valve 20 is executed. (S104). In this process, the valve timing of the intake valve 20 is controlled to the advanced side from the most retarded state to cause a valve overlap, so that the exhaust gas of the engine 1 contained in the gas in the combustion chamber 3 at the time of fuel combustion. The amount (internal EGR amount) is adjusted to the increasing side.

When the temperature of the combustion chamber 3 is raised by this exhaust gas, the fuel injected and supplied into the combustion chamber 3 is prevented from being atomized and remaining as a liquid fuel. Furthermore,
Since the combustion temperature of the fuel is lowered by the exhaust gas existing in the combustion chamber 3 at the time of fuel combustion, the burning of the liquid fuel in the combustion chamber 3 due to the combustion heat is also suppressed. In this way
By reducing the combustion temperature when the fuel burns while reducing the liquid fuel in the combustion chamber 3, it is possible to suppress the generation of black smoke due to the burning of the liquid fuel.

On the other hand, when a negative determination is made in step S103, it is determined that it is not necessary to suppress the above-described generation of black smoke, and normal valve timing control is executed (S105).

The above-mentioned valve timing advance control (S1
04) and normal valve timing control (S105)
This is realized by duty-controlling the applied voltage to the electromagnetic solenoid 34 of the OCV 28 based on the duty ratio D calculated / set by the electronic control unit 35. That is, the hydraulic pressure acting on the variable valve timing mechanism 25 is controlled by such duty control, and the valve timing of the intake valve 20 is adjusted by the operation of the mechanism 25 based on this hydraulic pressure control.

The normal valve timing control and the valve timing advance angle control will be individually described in detail. [Normal Valve Timing Control] In the normal valve timing control, the advance amount of the valve timing of the intake valve 20 is adjusted according to the operating state of the engine 1 such as the load factor KL and the engine rotation speed NE. This advance amount is
It is a value indicating how much the valve timing is advanced with reference to the time when the valve timing is in the most retarded state. In other words, the advance amount is a variable valve timing from the position (reference position) when the valve timing variable mechanism 25 sets the valve timing of the intake valve 20 to the most retarded state, to the side that advances the valve timing. This is the operation amount of the mechanism 25.

The adjustment of the advance amount of the valve timing in the normal valve timing control is performed by the load factor K.
This is performed by changing the duty ratio D so that the actual advance amount θr obtained from the detection signal of the cam position sensor 24 approaches the target advance amount θt set according to L and the engine speed NE.

When the duty ratio D is set to "0%", oil is supplied to the variable valve timing mechanism 25 through the retard side oil passage 27, whereby the valve timing of the intake valve 20 is maximized. The variable valve timing mechanism 25 operates so as to be in the retarded state as described above. On the other hand, the duty ratio D is "10.
When set to "0%", oil is supplied to the variable valve timing mechanism 25 through the advance side oil passage 26, so that the valve timing of the intake valve 20 is changed to the most advanced state. The mechanism 25 will operate.

Therefore, as for the duty ratio D in the normal valve timing control, the actual advance amount θr is the target advance amount θt.
If the value is on the valve timing advance side of
% ”, The actual advance amount θr is set to the target advance amount θ.
When the value is on the retard side of t, the value is set to a value closer to "100%". In this way, by changing the duty ratio D based on the actual advance amount θr and the target advance amount θt,
The actual advance amount θr is brought close to the target advance amount θt, and the valve timing of the intake valve 20 is set to the optimum timing for the operation of the engine 1.

[Valve Timing Advance Control] In the valve timing advance control, the duty ratio D is set to “100%” when the valve timing of the intake valve 20 has never reached the maximum advance after starting the engine. As a result, the valve timing variable mechanism 25 operates so that the valve timing of the intake valve 20 is in the most advanced state. When the valve timing of the intake valve 20 reaches the most advanced angle even once, the duty ratio D is calculated so that the actual advanced angle amount θr approaches the target advanced angle amount θt calculated based on the estimated temperature T. Become.

This target advance angle amount θt is, for example, the estimated temperature T
Is calculated as the value becomes higher. This is because as the estimated temperature T increases, less of the fuel injected and supplied into the combustion chamber 3 becomes liquid fuel without being atomized, and the valve timing of the intake valve 20 is adjusted to the advance side. This is because it is possible to suppress the generation of black smoke without increasing the amount of exhaust gas (internal EGR amount) existing in the combustion chamber 3 during fuel combustion.

By the way, when the engine 1 is stopped, the pressure (oil pressure) of the oil normally supplied to the valve timing variable mechanism 25 and the reaction force associated with the opening / closing drive of the intake valve 20 act on the valve timing variable mechanism 25. As a result, the variable mechanism 25 is returned to the side (reference position side) where the valve timing of the intake valve 20 is the most retarded angle.

However, if the engine 1 is stopped relatively early after the valve timing advance control is performed when the engine is started, the variable valve timing mechanism 25 may not return to the reference position. The cause of this is
It is conceivable that the engine 1 is stopped before the oil is warmed to a low viscosity, or that a high viscosity oil is used.

When the engine 1 is restarted while the variable valve timing mechanism 25 has not returned to the reference position, the fuel injection is performed with the valve timing of the intake valve 20 advanced from the most retarded state. Will be started. When the fuel combustion is performed under such a condition, the amount of exhaust gas (internal EGR amount) in the gas existing in the combustion chamber 3 at the time of fuel combustion becomes excessively larger than an appropriate value. Will be insufficient for good fuel combustion. Therefore, the air-fuel ratio of the engine 1 becomes excessively rich, which may lead to a start failure.

Therefore, in this embodiment, whether or not the advance amount of the intake valve 20 is larger than the predetermined value a at the start of the cold start, that is, the valve timing variable mechanism 25 moves from the internal EGR amount increasing side to the reference position. It is judged whether or not it has not returned to the vicinity. When the advance amount of the intake valve 20 is larger than the predetermined value a, the variable valve timing mechanism 2
When it is determined that 5 has not returned to the vicinity of the reference position, the fuel injection amount during the start-up of the engine 1 and immediately after the start-up is reduced and corrected.

By correcting the fuel injection amount in this way, when the oxygen shortage occurs due to the excessive internal EGR amount described above, the air-fuel ratio of the engine 1 becomes excessively rich, and the air-fuel ratio It is possible to suppress the start failure due to the rich condition.

Next, with respect to the procedure for setting the start control change flag F1 for determining whether or not to perform the reduction correction of the fuel injection amount, referring to the flowchart of FIG. 3 showing the start control change flag setting routine. explain. This start control change flag setting routine is periodically executed by the electronic control unit 35, for example, by a time interrupt at every predetermined time.

In the start control change flag setting routine, the current actual advance amount θr is stored in a predetermined area of the backup RAM as the advance amount θoff during engine operation (S201). Therefore, from the time the engine 1 is stopped to the time it is started, the actual advance angle θr at the time the engine is stopped
Is stored as the amount of advance angle θoff.

At the start of engine 1 (S
(202: YES), it is determined whether the advance amount θoff is larger than the predetermined value a (S203). If a positive determination is made and it is determined that the variable valve timing mechanism 25 has not returned to the vicinity of the reference position, the start control change flag F1 is set to "1 (execution)" (S204). .

As described above, the start control change flag F1 is set to "1".
When set to “(execution)”, execution of the reduction correction of the fuel injection amount during starting and immediately after completion of starting is instructed. The start control change flag F1 set to "1 (execution)" is "0 (non-execution)" when the engine 1 is stopped.
Is reset to.

Next, with respect to the procedure for calculating the final fuel injection amount Qfin which is the command value of the fuel injection amount when performing the fuel injection amount control during the start and after the completion of the start, FIG. This will be described with reference to the flowchart of FIG.

In the final fuel injection amount calculation routine,
When it is determined that the engine 1 is starting (S301
(FIG. 4): YES), the final fuel injection amount Qfin used during engine start is calculated (S303 to S31).
5 (FIGS. 5 and 6)). Further, when it is determined that the engine 1 is in the start-up completed state (S302 (FIG. 4): YE
S), the final fuel injection amount Qfin used after the completion of the engine start is calculated (S316 to S324 (FIG. 7)).

First, the procedure for calculating the final fuel injection amount Qfin used during engine startup will be described with reference to FIGS. 5 and 6. Here, the start-time injection amount Qst is calculated based on the cooling water temperature (S303 (FIG. 5)), and the correction coefficient K1 used to correct the reduction of the fuel injection amount during the engine start is calculated and set (S304-). S314 (FIG. 5, FIG. 6)) is sequentially performed. And, these starting injection quantity Q
Based on st, the correction coefficient K1, and other correction coefficients A1, the final fuel injection amount Qfin is calculated from the following equation (1) (S315 (FIG. 6)).

Qfin = Qst · A1 · K1 (1) When the final fuel injection amount Qfin is calculated in this manner, the fuel injection valve 4 is electronically controlled so that the corresponding amount of fuel is injected into the combustion chamber 3. The drive is controlled through the device 35.

The correction coefficient K1 is determined that the start control change flag F1 is not "1 (execution)" (S304: NO) and it is not necessary to execute the above-described correction for reducing the fuel injection amount during engine startup. When it is done, it is set to "1.0" (S311). In this way, when the correction coefficient K1 is set to "1.0", the reduction correction of the fuel injection amount during engine start is not executed.

When the start control change flag F1 is "1 (execution)" (S304: YES), it is determined whether or not the number of fuel injections from the start is greater than or equal to the number of cylinders, that is, all the fuel is injected after the start. It is determined whether fuel combustion has been performed in the cylinder (S305). If a negative determination is made here, the correction coefficient K1 is set to "0" as in the above (S31).
1). This is because the first fuel combustion in each cylinder,
Since the internal EGR amount is almost “0”, it is unlikely that the air-fuel ratio becomes excessively rich due to the lack of oxygen due to the excessive internal EGR amount. Even when “F1 = 1”, the above-mentioned engine is being started. This is because it is not necessary to perform the reduction correction of the fuel injection amount of.

If the affirmative determination is made in step S305, it is determined whether or not the number of fuel injections from the start of the engine is equal to the number of cylinders, that is, the fuel injection in the next fuel injection is performed in all the cylinders. It is determined whether or not it is the first time (S306). If an affirmative determination is made here, the correction coefficient K1 is calculated based on the advance amount θoff and the piston temperature.
An initial value K01 is calculated (S307), and the initial value K
01 is set as the correction coefficient K1 (S308).

The piston temperature used for calculation of the initial value K01 is an estimated value of the piston temperature at the start of starting, and the running time in the engine operation immediately before the start or the execution of the engine operation is performed. It is estimated based on the cumulative intake air amount, the cumulative fuel injection amount, etc. Further, in estimating the piston temperature, if the engine stop time from the last engine operation to the present engine start is taken into consideration, the estimation can be performed more accurately.

Initial value K0 calculated in step S307
As shown in FIG. 8, 1 changes according to the change of the piston temperature so that it becomes minimum when the piston temperature reaches a predetermined value under the condition that the advance amount θoff is constant. Therefore, under the condition that the advance amount θoff is constant, when the piston temperature reaches the above-mentioned predetermined value, the reduction correction amount of the fuel injection amount during engine start becomes maximum. It should be noted that the above-described change in the initial value K01 depending on the piston temperature is such that the higher the piston temperature, the smaller the amount of the injected fuel that adheres to the inner wall surface of the combustion chamber 3 becomes, but This is because of the property that the amount is large.

Further, the initial value K01 becomes smaller as the advance amount θoff becomes larger under the condition that the piston temperature is constant. This is because the internal EGR increases as the advance angle θoff increases.
This is because it is possible to suppress that the amount becomes excessive and the shift of the air-fuel ratio to the rich side due to lack of oxygen easily proceeds.

On the other hand, when a negative determination is made in step S306 and it is determined that the next fuel injection is after the second time after the fuel combustion in all the cylinders,
A new correction coefficient K1 is obtained by adding the predetermined value b to the correction coefficient K1 used in the previous calculation of the final fuel injection amount Qfin.
Is set as (S309). Then, the correction coefficient K
1 is "1.0" and the upper limit is guarded (S310).

After the correction coefficient K1 is calculated and set as described above, whether or not a predetermined time has elapsed from the start of the start,
That is, it is determined whether or not the start has not been completed even after a predetermined time has elapsed from the start of the start (S312 (FIG. 6)). If an affirmative determination is made here, it is determined that the reduction correction of the fuel injection amount during engine start is excessively performed, and the start control change flag F1 is set to "0 (non-execution)" (S313). The correction coefficient K1 is set to "1.0" (S314). By setting the correction coefficient K1 to "1.0" in this way, the reduction correction of the fuel injection amount during the engine start is stopped, and the startability of the engine 1 when the reduction correction is excessive. Is suppressed.

Next, the procedure for calculating the final fuel injection amount Qfin used after the engine 1 is completely started will be described with reference to FIG. Here, the basic fuel injection amount Qbse is calculated based on the engine speed NE and the load factor KL (S3
16), and calculation of the correction coefficient K2 used for the correction correction of the fuel injection amount immediately after the completion of the engine start described above.
Settings (S317 to S323) are sequentially performed. And
The final fuel injection amount Qfin is calculated from the following equation (2) based on the starting injection amount Qst, the correction coefficient K2, and the other correction coefficient A2 (S324).

Qfin = Qst · A1 · K1 (2) When the final fuel injection amount Qfin is calculated in this manner, the fuel injection valve 4 is electronically controlled so that the fuel of the corresponding amount is injected into the combustion chamber 3. The drive is controlled through the device 35.

With respect to the correction coefficient K2, the start control change flag F1 is not "1 (execution)" (S317: NO), and it is not necessary to execute the above-described correction for reducing the fuel injection amount immediately after the completion of the engine start. If judged, "1.
It is set to "0" (S323). Thus, the correction coefficient K
When 1 is set to "1.0", the reduction correction of the fuel injection amount immediately after the completion of the engine start is not executed.

When the start control change flag F1 is "1 (execution)" (S317: YES), it is determined whether or not the next fuel injection is the first one after completion of the start (S318). ). If a positive determination is made here, an initial value K02 of the correction coefficient K2 is calculated based on the advance amount θoff and the piston temperature (S319), and this initial value K02 is set as the correction coefficient K2 (S32).
0).

The initial value K02 calculated as described above is
As shown in FIG. 9, under the condition that the advance amount θoff is constant, the piston temperature changes in accordance with the change of the piston temperature so that it becomes minimum when the piston temperature reaches a predetermined value. Therefore, under the condition that the advance amount θoff is constant, when the piston temperature reaches the above-mentioned predetermined value, the reduction correction amount of the fuel injection amount during engine start becomes maximum. Also, the initial value K02
Is the advance angle θoff under the condition that the piston temperature is constant.
Becomes larger, becomes smaller.

The initial value K02 is changed with respect to the changes in the advance angle θoff and the piston temperature in this way because the initial value K01 is changed with respect to the changes in the advance angle θoff and the piston temperature.
For the same reason as shown in FIG.

On the other hand, when a negative determination is made in step S318 and it is determined that the next fuel injection is the second or later fuel injection after completion of the start, the last final fuel injection amount Qfi
A value obtained by adding a predetermined value c to the correction coefficient K2 used for calculating n is set as a new correction coefficient K2 (S32).
1). Subsequently, the correction coefficient K1 is guarded with an upper limit of "1.0" (S322).

Finally, FIG. 1 shows the manner in which the fuel injection amount is reduced during the starting of the engine 1 and immediately after the completion of the starting.
Please refer to the time chart of 0 as well. When the variable valve timing mechanism 25 has not returned to the reference position at the start of the engine and the internal EGR amount may be excessive, until the first fuel combustion in each cylinder is executed (timing T1). , The correction coefficient K1 is “1.
It is set to "0" and the normal fuel injection at the time of starting is performed.

Then, in the first fuel injection after the first fuel combustion in each cylinder is executed, the correction coefficient K1 is set to the initial value K01 and the reduction correction of the fuel injection amount during the engine start is started. It As for the amount of reduction correction of the fuel injection amount at this start, the initial value K01 is the advance amount θoff.
And the piston temperature, as shown in FIG. 8, the same changes according to the advance amount θoff and the piston temperature. After the start of the reduction correction of the fuel injection amount during the engine start, the correction coefficient K1 is brought closer to the "1.0" side by the predetermined value b for each predetermined cycle, and the reduction correction amount of the fuel injection amount is gradually reduced. To be done.

When the reduction correction of the fuel injection amount during the engine start is performed and the start of the engine 1 is completed, instead of the reduction correction of the fuel injection amount by the correction coefficient K1 during the engine start, Immediately after the start is completed, the correction correction of the fuel injection amount by the correction coefficient K2 is executed.

That is, the correction coefficient K2, which was "1.0", is set to the initial value K02, and the reduction correction of the fuel injection amount immediately after the completion of the engine start is started. The reduction correction amount of the fuel injection amount at the time of the start changes the initial value K02 according to the advance amount θoff and the piston temperature as shown in FIG. Will change. After the start of the reduction correction of the fuel injection amount immediately after the completion of the engine start, the correction coefficient K2 is brought closer to the “1.0” side by the predetermined value c for each predetermined cycle, and the reduction correction amount of the fuel injection amount is gradually increased. Be reduced.

As described above, by performing the correction correction of the fuel injection amount during the start of the engine 1 and immediately after the completion of the start, the variable valve timing mechanism 25 has not returned to the reference position at the start of the start, and the internal EGR amount is reduced. Even if the oxygen deficiency occurs due to the excess, the air-fuel ratio is prevented from becoming excessively rich due to the oxygen deficiency.

Further, when the engine is being started and the start has not been completed at the time when a predetermined time has passed from the start (timing T2), the fuel injection amount reduction correction is excessively performed during the engine start. The correction coefficient K1 is set to "1.0". As a result, the reduction correction of the fuel injection amount during the engine start is stopped, and the deterioration of the engine startability due to the excessive reduction correction of the fuel injection amount is suppressed. Further, in this case, the correction coefficient K2 is maintained at "1.0" after the engine start is completed.
As a result, the reduction correction of the fuel injection amount immediately after the completion of the engine start is also stopped, and useless execution of the reduction correction is suppressed.

According to this embodiment described in detail above, the following effects can be obtained. (1) When the variable valve timing mechanism 25 has not fully returned to the vicinity of the reference position at the time of starting the engine 1, the internal EGR amount becomes excessively large and oxygen is insufficient for obtaining good fuel combustion, The air-fuel ratio of 1 may become excessively rich. However, at the time of starting the engine 1, when it is determined that the advance amount θoff is larger than the predetermined value a and the variable valve timing mechanism 25 has not returned to the vicinity of the reference position, the fuel injection amount reduction correction is performed. Will be executed. By this reduction correction of the fuel injection amount, it is possible to prevent the air-fuel ratio from becoming excessively rich due to the excessive amount of the internal EGR amount and starting failure.

(2) Reduction correction of the fuel injection amount during engine start is started on condition that the first fuel combustion is performed in all cylinders after the start of start. Therefore, the internal EGR
When the fuel is burned for the first time when the amount is almost “0”, unnecessary reduction correction of the fuel injection amount is performed, whereby it is possible to prevent the fuel injection amount from becoming insufficient and leading to a start failure.

(3) The initial value of the fuel injection amount reduction correction amount during the engine start and immediately after the completion of the engine start (initial value K
(Corresponding to 01 and K02) is variable so that it becomes larger as the advance angle amount θoff is larger. Since the internal EGR amount changes according to this advance angle amount θoff, by making the initial value of the reduction correction amount variable as described above, the reduction amount of internal EGR is corrected.
It becomes possible to appropriately perform the suppression of the rich air-fuel ratio due to the excessive amount of R.

(4) Further, the initial value of the above-mentioned weight reduction correction amount is
It also becomes variable based on the piston temperature. When the piston temperature changes, the amount of fuel adhering to the inner wall surface of the combustion chamber 3 that affects the air-fuel ratio of the engine 1 and the amount of vaporization of the adhering fuel change. Therefore, by making the initial value of the reduction correction amount variable as described above, the reduction correction can be appropriately performed according to the fuel adhesion amount to the inner wall surface of the combustion chamber 3 and the vaporization amount of the adhesion fuel. it can.

(5) The reduction correction amount of the fuel injection amount during the engine start and immediately after the completion of the engine start is gradually reduced after the correction is started. Therefore, it is possible to prevent a problem such as torque shock from occurring due to the reduction correction amount suddenly becoming “0”.

(6) When the reduction correction of the fuel injection amount during the engine start is being executed, if it is determined that the start is not completed even after a lapse of a predetermined time from the start of the engine, the fuel injection amount of the fuel injection amount is changed. Weight loss correction is stopped. Therefore, even if the engine 1 becomes difficult to start due to the reduction correction of the fuel injection amount during the engine start, it is possible to accurately judge that fact and stop the reduction correction, and the startability of the engine 1 is improved. It is possible to suppress the decrease due to the weight reduction correction.

(7) When it is determined that the engine has not been started even after the lapse of a predetermined time from the start as described above, the reduction correction of the fuel injection amount immediately after the completion of the engine start is also stopped. The useless execution of the weight reduction correction can be suppressed.

The present embodiment can be modified as follows. The reduction correction amount of the fuel injection amount during the engine start and immediately after the completion of the engine start is gradually reduced every predetermined time, but it is also possible to be gradually reduced every time the fuel injection is performed, for example. .

The initial value of the reduction correction amount is set to the advance amount θof
Although variable depending on both f and the piston temperature, it may be variable according to only one of them or may be a fixed value.

It is also possible to perform only the reduction correction of the fuel injection amount during engine startup. Although the amount reduction correction is not performed in the first fuel injection in each cylinder after the start of the engine, the amount reduction correction may be performed in the first fuel injection in each cylinder instead.

When the fuel injection amount reduction correction is being performed while the engine is being started and the completion of the start is slow, the reduction correction is stopped. However, such a reduction correction stop process is not necessarily performed. There is no.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The present embodiment differs from the first embodiment in that the advance amount used for setting the start control change flag F1 is obtained when the engine 1 is started.

FIG. 11 is a flow chart showing the start control change flag setting routine of this embodiment. In the start control change flag setting routine, after it is started (S403: YES), when it is determined that the engine rotation is stable enough to calculate the actual advance amount θr (S402: YES), cam position sensor 2
The actual amount of advance angle θr is calculated based on the detection signal from S4 (S403).

After starting the engine 1,
Fuel injection from the fuel injection valve 4 is prohibited until the engine rotation becomes stable enough to calculate the actual advance amount θr (S402: NO) (S406). By prohibiting fuel injection in this way, it is possible to prevent the engine rotation from becoming unstable due to fuel combustion, to perform stable engine rotation due to cranking, and to quickly complete the calculation of the actual advance angle amount θr. Will be able to.

After the calculation of the actual advance angle amount θr, it is determined whether or not the actual advance angle amount θr is larger than the predetermined value a (S404). If the determination is affirmative, the start control change flag F is determined.
1 is set to “1 (execution)”. Then, "F1 =
By setting "1", the fuel injection amount reduction correction is performed during the engine start and immediately after the engine start is completed.

Also in this embodiment, the same effects as (1) to (7) described in the first embodiment can be obtained. (Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIG.
It will be explained based on.

In this embodiment, the start control change flag F1
Variable valve timing mechanism 25 when setting
Is not returned to near the reference position,
The difference from the first embodiment is that the operation is performed based on whether or not the viscosity of oil for operating the variable mechanism 25 is high.

FIG. 12 is a flow chart showing the start control change flag setting routine of this embodiment. In this start control change flag setting routine, at the start of start (S501: YES), whether or not the engine operating time t after the valve timing advance control is started in the previous engine operation is less than the predetermined value d. Is determined (S50
2). As the operating time t becomes longer, the oil for operating the variable valve timing mechanism 25 is heated and the viscosity becomes lower.
When a positive determination is made in 02, it can be estimated that the viscosity of the oil is high.

When it is estimated that the oil viscosity is high (S502: YES), the valve timing changing mechanism 25
Is determined not to have returned to the vicinity of the reference position, and the start control change flag F1 is set to "1 (execution)" (S5).
03). By setting “F1 = 1” in this way,
Reduction correction of the fuel injection amount is performed during the engine start and immediately after the engine start is completed.

In the start control change flag setting routine, the processing from step S504 should be performed at the next engine start by using the engine operation time t after the valve timing advance control in this engine operation is started. It is for calculating and storing.

In this series of processes, the counter C is incremented at predetermined intervals during the valve timing advance control (S504, S50).
5). Then, when the engine 1 is stopped (S506: YE
S), the product of the count value of the counter C and the conversion coefficient h is stored in a predetermined area of the backup RAM as the engine operating time t (S507). This conversion factor h
Is for converting the count value of the counter C into a unit of time.

The engine operating time t thus stored is used when the engine is started next time. The counter C is cleared to “0” after the storage of the engine operating time t is completed (S508).

In this embodiment, it is possible to judge that the valve timing variable mechanism 25 has not returned to the vicinity of the reference position when the engine is started based on the fact that the oil viscosity is estimated to be high. The same effects as described in (1) to (7) can be obtained.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. In the present embodiment, when the start control change flag F1 is "1 (execution)", the valve timing variable mechanism 25 is used as a reference instead of executing the reduction correction of the fuel injection amount during the engine start and immediately after the completion of the engine start. The position side is controlled. By controlling the variable valve timing mechanism 25 in this way, an excessive amount of internal EGR amount at the time of starting the engine 1 is suppressed, and a resulting rich air-fuel ratio is also suppressed.

FIG. 13 is a flow chart showing a starting control routine for controlling the variable valve timing mechanism 25 as described above. This start control routine is periodically executed through the electronic control unit 35 by, for example, a time interruption at every predetermined time.

In the start control routine, the start control change flag F1 is not "1 (execution)" (S601:
NO), the valve timing advance control is executed as usual, and the normal fuel injection amount control without the fuel injection amount reduction correction as in the first to third embodiments is executed (S604, S605). .

On the other hand, if the start control change flag F1 is "1 (execution)", it is determined that the variable valve timing mechanism 25 has not returned to the vicinity of the reference position when the engine is started, and the actual advance amount θr is never reached. The duty ratio D is set to "0%" on condition that it is not less than the predetermined value e (S602, S603).

Therefore, the start control change flag F1 is "1".
(Execution) ”, the duty ratio D is fixed to“ 0% ”until the actual advance amount θr becomes less than the predetermined value e even once, and the valve timing variable mechanism 25 is controlled to the reference position side. It At this time, the normal fuel injection amount control is executed (S605), but since the control of the valve timing variable mechanism 25 to the reference position side suppresses the excess of the internal EGR amount, the rich air-fuel ratio is also suppressed. To be done. After that, when the actual advance angle amount θr becomes less than the predetermined value e, an affirmative determination is made thereafter in step S602, and the normal valve timing advance angle control is executed.

According to this embodiment, the following effects can be obtained. (8) When it is determined that the variable valve timing mechanism 25 has not returned to the vicinity of the reference position when the engine 1 is started, the variable timing mechanism 25 is controlled to the reference position side.
Therefore, it is possible to prevent the internal EGR amount from becoming excessive due to the variable mechanism 25 not returning to the vicinity of the reference position, resulting in excessively rich air-fuel ratio and starting failure. it can.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, when the start control change flag F1 is "1 (execution)", the valve timing variable mechanism 25 is controlled to the reference position side as in the fourth embodiment, and while the control is being performed. Is for stopping the fuel injection. Since the scavenging of the combustion chamber 3 is performed by temporarily stopping the fuel injection as described above, the fuel combustion is not performed in the state where the internal EGR amount is excessive. Therefore, it is possible to accurately suppress that the fuel combustion in this state is performed and the air-fuel ratio becomes excessively rich, which leads to a start failure of the engine 1.

FIG. 14 is a flowchart showing a starting control routine for controlling the variable valve timing mechanism 25 as described above and for stopping the fuel injection.
This start control routine differs from the fourth embodiment only in the processes (steps S703 to S706) corresponding to the processes after step S603 in the start control routine (FIG. 13) of the fourth embodiment.

In the startup control routine of this embodiment, if the startup control change flag F1 is "1 (execution)" (S701: YES), the variable valve timing mechanism 25 has returned to the vicinity of the reference position when the engine is started. If it is determined that the actual advance angle θr is not less than the predetermined value e, the fuel injection is stopped and the duty ratio D is set to "0%" (S702 to S702).
704).

By setting the duty ratio D to "0%" in this manner, the variable valve timing mechanism 25 is controlled to the reference position side. After that, the actual advance amount θr is the predetermined value e.
If it is less than this, the affirmative determination will be made thereafter in step S702, and the normal fuel injection amount control and valve timing advance control will be executed (S705,
S706).

According to this embodiment, the following effects can be obtained. (9) When it is determined that the valve timing variable mechanism 25 has not fully returned to the vicinity of the reference position when the engine 1 is started, the variable timing mechanism 25 is controlled to the reference position side, and while the control is being performed. Fuel injection is stopped. The scavenging of the combustion chamber 3 is performed by the stop of the fuel injection, and the fuel combustion is not performed when the internal EGR amount is excessive. Therefore, it is suppressed that the fuel combustion is performed in this state and the air-fuel ratio becomes excessively rich, which leads to a poor starting of the engine 1.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIG. In this embodiment, when the engine 1 is stopped, the variable valve timing mechanism 25 returns to the vicinity of the reference position, and then the engine 1 is stopped. With this configuration, it is possible to avoid a situation in which the variable valve timing mechanism 25 is not fully returned to the vicinity of the reference position when the engine 1 is started.

FIG. 15 is a flow chart showing an engine stop routine for stopping the engine 1 as described above. The engine stop routine is periodically executed by the electronic control unit 35, for example, at predetermined time intervals by time interruption.

In the engine stop routine, when the engine stop command is issued (S801: YES), the duty ratio D is set to "0%" (S802). As a result, the variable valve timing mechanism 25 is controlled to the reference position side. Then, the actual advance amount θr becomes less than the predetermined value f (S803: YES), and the valve timing variable mechanism 2
When it is determined that the number 5 has returned to the vicinity of the reference position, the stop of the engine 1 is started (S804).

According to this embodiment, the following effects can be obtained. (10) Since the engine start will not be performed in a situation where the variable valve timing mechanism 25 has not fully returned to the vicinity of the reference position, the fuel injection for engine start is performed in such a situation, so that the air-fuel ratio is increased. Can be prevented from becoming excessively rich and starting failure occurs.

The present embodiment can be modified as follows, for example. The engine 1 may be stopped as described above only when the valve timing advance control is executed.
In this case, it can be avoided that it takes more time than necessary to stop the engine 1.

After the engine 1 stop command, the actual advance amount θr
The engine 1 started to stop when was less than the predetermined value f, but instead of this, the engine operation is continued for the time required for the valve timing variable mechanism 25 to return to the vicinity of the reference position after the engine 1 stop command is issued. However, it is also possible to start the stop of the engine 1 after the time has elapsed.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described with reference to FIGS. The present embodiment evaluates the operation of the variable valve timing mechanism 25 at the time of low temperature start in which the valve timing advance control is performed, and suspends the valve timing advance control when it is determined that the operation of the variable mechanism 25 is slow. Is. If it is determined that the operation of the variable valve timing mechanism 25 is slow, and if the valve timing advance control is performed, there is a high possibility that the variable mechanism 25 will not fully return to the vicinity of the reference position in the subsequent engine stop process. However, by stopping the valve timing advance control as described above, such a situation is prevented.

FIG. 16 is a flow chart showing the black smoke suppression routine of this embodiment. This black smoke suppression routine differs from that of the first embodiment (FIG. 2) in step S
The processes of 904 and S907 are added.

That is, the estimated temperature T of the combustion chamber 3 after the start of starting
Is calculated (S901, S902), and it is determined that the estimated temperature is equal to or less than the predetermined value a2 and the generation of black smoke should be suppressed (S903: YES), the valve timing advance control (S905). It is determined whether or not the advance control stop flag F2 used for determining whether or not to stop is "0 (not stopped)". If a negative determination is made here, the duty ratio D is set to "0%" (S9
07), whereby the variable valve timing mechanism 25 is controlled to the reference position side, and the valve timing advance control (S9
05) will be canceled.

If a negative determination is made in step S903 and it is determined that it is not necessary to suppress the black smoke generation, normal valve timing control is executed (S906).

Here, the procedure for setting the advance angle control stop flag F2 will be described with reference to the flowchart of FIG. 17 showing the advance angle control stop flag setting routine. This advance angle control stop flag setting routine is periodically executed by the electronic control unit 35 by a time interruption at every predetermined time.

In the advance angle control stop flag setting routine, the valve timing advance angle control is started when the engine is started (S1001: YES), and the advance angle control stop flag F2 is "0" (not executed). ) ”(S1002: YES), step S100 for evaluating the operation of the variable valve timing mechanism 25.
3, the processing of S1004 is executed.

In the processes of steps S1003 and S1004, it is determined whether or not the actual advance amount θr at the time when a predetermined time has elapsed from the start of the advance control is less than the predetermined value g, that is, the valve timing of the intake valve 20 is advanced. It is determined whether or not the operation of the variable valve timing mechanism 25 toward the turning side is slow. When it is determined that the actual advance angle amount θr is less than the predetermined value g and the operation of the variable valve timing mechanism 25 is slow, the advance angle control stop flag F2 is set to "1 (stop)" (S1005). ). When the advance control stop flag F2 is set to "1 (stop)" in this way, the valve timing advance control is stopped in the black smoke suppression routine shown in FIG.

In this embodiment, the following effects can be obtained. (11) When it is determined that the operation is slow as a result of the operation evaluation of the valve timing variable mechanism 25 performed at the time of starting the engine, the valve timing advance control is stopped. For this reason, it is possible to prevent a situation in which the valve timing variable mechanism 25 is not actuated slowly and cannot return to the reference position in the engine stop process. When the above situation occurs, it is possible to prevent the start-up failure from occurring due to the air-fuel ratio becoming excessively rich due to the excessive internal EGR amount when the engine is started.

(12) The cause of the situation in which the variable valve timing mechanism 25 cannot fully return to the reference position in the engine stop process is that a highly viscous oil is used as the oil for operating the mechanism 25. Can also be considered. Even if the above situation occurs due to such a cause, the occurrence thereof can be suppressed.

(Eighth Embodiment) Next, an eighth embodiment of the present invention will be described with reference to FIGS. 18 and 19. In the present embodiment, the oil for operating the valve timing varying mechanism 25 at the time of engine start is heated for a predetermined time to reduce the viscosity of the oil, and the high viscosity causes the variable mechanism 25 to operate at the time of starting. This suppresses a situation in which the vehicle has not completely returned to the vicinity of the reference position.

FIG. 18 shows a heater 3 for heating the oil.
7 is a schematic view showing an installation mode of FIG. The heater 37 is provided in the middle of the supply passage 29 and the discharge passage 30 and heats the oil flowing through the passages 29 and 30. The heating of oil by the heater 37 is controlled by the electronic control unit 35.

FIG. 19 is a flow chart showing an oil heating routine for heating the oil by the heater 37. This oil heating routine is performed by the electronic control unit 35.
Through, for example, a periodical interrupt is executed at predetermined time intervals.

In the oil heating routine, the heating of the oil by the heater 37 is started at the start of starting the engine 1 (S1101: YES), and when the predetermined time has elapsed from the start of starting (S1103: YES). The heating of the oil by 37 is stopped (S110).
4).

In this embodiment, the following effects can be obtained. (13) In the starting process of the engine 1, the oil is heated for a predetermined time to reduce the viscosity. Therefore, when the engine 1 is stopped immediately after the valve timing advance control is started at the low temperature start, the oil is It is possible to prevent a situation in which the variable valve timing mechanism 25 cannot fully return to the reference position during the engine stop process due to the high viscosity. When the above situation occurs, it is possible to prevent the start-up failure from occurring due to the air-fuel ratio becoming excessively rich due to the excessive internal EGR amount when the engine is started.

The present embodiment can be modified as follows, for example. The oil may be heated only when the valve timing advance control is executed, instead of always heating the oil in the engine starting process. In this case, the heating of the oil by the heater 37 is started when the same advance control is started, and when the predetermined time elapses after the start or when the actual advance amount θr reaches the predetermined value, the heater is heated. It is conceivable to adopt an oil heating mode in which the heating of oil by 37 is stopped.

[0164] Instead of heating the oil in the engine starting process, the oil may be heated for a predetermined time in the engine stopping process. Also in this case, the same effect as described above can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of an engine to which a control device of a first embodiment is applied.

FIG. 2 is a flowchart showing a black smoke suppression procedure of the first embodiment.

FIG. 3 is a flowchart showing a procedure for setting a start control change flag in the first embodiment.

FIG. 4 is a flowchart showing a procedure for calculating a final fuel injection amount.

FIG. 5 is a flowchart showing a procedure for calculating a final fuel injection amount.

FIG. 6 is a flowchart showing a procedure for calculating a final fuel injection amount.

FIG. 7 is a flowchart showing a procedure for calculating a final fuel injection amount.

FIG. 8 is a graph showing changes in an initial value K01 with respect to changes in an advance amount θoff and a piston temperature.

FIG. 9 is a graph showing changes in an initial value K02 with respect to changes in an advance amount θoff and a piston temperature.

FIG. 10 is a time chart showing changes in initial values K01 and K02 with the lapse of time after the start of the engine.

FIG. 11 is a flowchart showing a procedure for setting a start control change flag in the second embodiment.

FIG. 12 is a flowchart showing a procedure for setting a start control change flag according to the third embodiment.

FIG. 13 is a flowchart showing a procedure of valve timing control and fuel injection amount control at the time of engine startup in the fourth embodiment.

FIG. 14 is a flowchart showing a procedure of valve timing control and fuel injection amount control at the time of engine startup in the fifth embodiment.

FIG. 15 is a flowchart showing an engine stop procedure in the sixth embodiment.

FIG. 16 is a flowchart showing a black smoke suppression procedure in the seventh embodiment.

FIG. 17 is a flowchart showing a procedure for setting an advance angle control stop flag.

FIG. 18 is a schematic view showing an installation example of a heater.

FIG. 19 is a flowchart showing an oil heating procedure.

[Explanation of symbols]

1 ... Engine, 3 ... Combustion chamber, 4 ... Fuel injection valve, 10 ... Crank position sensor, 11 ... Throttle valve, 1
2 ... Vacuum sensor, 14 ... Accelerator position sensor, 15 ... Throttle position sensor, 20 ... Intake valve, 21 ... Exhaust valve, 24 ... Cam position sensor, 25 ... Valve timing variable mechanism, 28 ... Oil control valve (OCV), 35 ... Electronic control unit, 3
6 ... Water temperature sensor, 37 ... Heater.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 41/04 301 F02D 41/04 301H 41/06 320 41/06 320 330 330 330A 330B 43/00 301 43 / 00 301H 301Z 45/00 310 45/00 310B 310G 312 312B 312G 312Q F02N 17/02 F02N 17/02 F 17/04 17/04 Z 17/08 17/08 Z (72) Inventor Jun Takahashi Toyota City, Aichi Prefecture Toyota Town No. 1 Toyota Motor Corporation (72) Inventor Yoshihiko Masuda No. 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation No. 1 (72) Inventor Kiyoo Hirose 1 Toyota Town, Aichi Prefecture Toyota Motor Corporation Stock In-house (72) Inventor Kazuhiro Iwahashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation Stock In-house F-term (reference) 3G084 BA13 BA23 BA26 CA01 CA02 CA07 DA09 EA07 EA11 EC01 EC03 FA00 FA18 FA20 FA33 3G092 AA01 AA06 AA11 BB01 DA01 DA10 DE03S DG05 DG09 EA01 EA02 EA02 HA13 HA01 HA13 HA01 HA13 FA01 FA13 FA01 FA18 FA21 FA18 FA21 FA18 FA21 FA18 FA21 FA18 FA21 FA13 FA01 FA13 FA01 HE08Z 3G301 HA19 JA00 KA01 KA02 KA04 KA26 KA28 LA07 MA11 MA24 NA08 NE17 NE23 PE00Z PE01Z PE08Z PE10Z

Claims (16)

[Claims] 1. A cylinder injection type internal combustion engine equipped with adjusting means for adjusting the amount of exhaust gas contained in the gas in a combustion chamber during fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for a cylinder injection internal combustion engine that executes an exhaust gas increase control that operates from a predetermined position to the side that increases the exhaust gas amount in the gas, at the time of starting the internal combustion engine, from the predetermined position in the adjusting means. A control device for a cylinder injection internal combustion engine, comprising: a correction unit that corrects the fuel injection amount from engine start-up based on an operation amount to the side that increases the exhaust gas amount. 2. A cylinder injection type internal combustion engine having an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion. The adjusting means is hydraulically operated when the engine is cold started. In a control device for a direct injection internal combustion engine that executes an exhaust amount increase control that operates from a predetermined position to the side that increases the exhaust amount in the gas, at the time of starting the internal combustion engine, the adjusting unit causes the exhaust amount in the gas. A control device for a cylinder injection internal combustion engine, comprising: a correction unit that corrects the fuel injection amount from the start of the engine in a reduced amount when it is determined that the fuel injection amount has not returned to the vicinity of the predetermined position from the side where the fuel injection amount is increased. 3. The in-cylinder injection internal combustion engine according to claim 1 or 2, wherein the correction means starts reduction correction of the fuel injection amount on condition that fuel combustion has been performed after starting the internal combustion engine. Control device. 4. The correction means starts the reduction correction of the fuel injection amount on condition that the first fuel combustion is performed in all cylinders of the internal combustion engine after the start of the internal combustion engine. Of a cylinder injection type internal combustion engine. 5. The initial value of the reduction correction amount of the fuel injection amount is
The control device for a cylinder injection internal combustion engine according to any one of claims 1 to 4, wherein the control device is variable based on an operation amount toward a side that increases an exhaust amount of the gas from a predetermined position in the adjusting unit. 6. The initial value of the reduction correction amount of the fuel injection amount is:
The control device for a cylinder injection internal combustion engine according to any one of claims 1 to 5, which is variable based on a piston temperature. 7. The control device for a cylinder injection internal combustion engine according to claim 5, wherein the correction amount for reducing the fuel injection amount is gradually reduced from the initial value with the lapse of time. 8. The correction means stops the reduction correction of the fuel injection amount when the start of the internal combustion engine is not completed even after a predetermined time has elapsed since the start of the internal combustion engine. Of a cylinder injection type internal combustion engine. 9. The present invention is applied to a cylinder injection internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber during fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for a cylinder injection internal combustion engine that executes an exhaust gas increase control that operates from a predetermined position to the side that increases the exhaust gas amount in the gas, at the time of starting the internal combustion engine, from the predetermined position in the adjusting means. A cylinder injection internal combustion engine characterized by comprising control means for controlling the adjusting means to the predetermined position side when the operation amount to increase the exhaust gas amount is larger than a predetermined value. Control device. 10. The present invention is applied to a cylinder injection internal combustion engine equipped with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for a direct injection internal combustion engine that executes an exhaust amount increase control that operates from a predetermined position to the side that increases the exhaust amount in the gas, at the time of starting the internal combustion engine, the adjusting unit causes the exhaust amount in the gas. The control device for a cylinder injection type internal combustion engine, comprising: a control means for controlling the adjusting means to the predetermined position side when it is determined that it has not returned to the vicinity of the predetermined position from the side of increasing the fuel injection amount. 11. The control means, when starting the internal combustion engine and controlling the adjusting means to the predetermined position side,
The control device for a cylinder injection internal combustion engine according to claim 9 or 10, wherein fuel injection is stopped until the adjusting means returns to a predetermined operating position on the predetermined position side. 12. When it is determined that the adjusting means has not returned to the vicinity of the predetermined position, the operation amount to the side of increasing the exhaust amount in the gas from the predetermined position in the adjusting means is higher than a predetermined value. The control device for a cylinder injection type internal combustion engine according to claim 2 or 10, which is made based on the fact that it is large. 13. The determination as to whether the adjusting means has not returned to the vicinity of the predetermined position is made based on the fact that the viscosity of the hydraulic oil used for hydraulic control of the adjusting means is estimated to be high. 10. The control device for a direct injection internal combustion engine according to item 10. 14. A cylinder injection type internal combustion engine provided with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for a cylinder injection internal combustion engine that executes an exhaust gas increase control that operates from a predetermined position to the side that increases the exhaust gas amount in the gas, at least after the exhaust gas increase control is executed at the time of starting the internal combustion engine. When stopping the engine, the adjusting means is provided with a stopping means for stopping the internal combustion engine on condition that it is judged that the adjusting means has returned to the vicinity of a predetermined position from the side of increasing the exhaust amount in the gas. A control device for a cylinder injection internal combustion engine. 15. The present invention is applied to a cylinder injection internal combustion engine equipped with an adjusting means for adjusting the amount of exhaust gas contained in the gas in the combustion chamber at the time of fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for a direct injection internal combustion engine that executes an exhaust amount increase control that operates from a predetermined position to the side that increases the exhaust amount in the gas, evaluates the operation of the adjusting means at the time of the low temperature start, and adjusts the same. A control device for a cylinder injection internal combustion engine, comprising: a canceling unit for canceling the exhaust gas increase control at the time of low temperature start when it is determined that the operation is slow. 16. The present invention is applied to a cylinder injection internal combustion engine equipped with adjusting means for adjusting the amount of exhaust gas contained in gas in a combustion chamber during fuel combustion, and the adjusting means is hydraulically operated when the engine is cold started. In a control device for an in-cylinder injection internal combustion engine that executes an exhaust amount increase control that operates to increase the amount of exhaust gas in a gas from a predetermined position, during a predetermined period in at least one of a stop process and a start process of the internal combustion engine. A control device for a cylinder injection internal combustion engine, further comprising heating means for heating the hydraulic oil for operating the adjusting means.