JP4396678B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  In an internal combustion engine such as an automobile engine, fuel and oil present in the intake system come into contact with the high-temperature wall surface and are carbonized and deposited as deposits, thereby reducing the air circulation area of the intake system. In the intake system of the engine, the higher the temperature of carbonization when the fuel or oil comes into contact, the higher the temperature at the back of the umbrella part of the intake valve or the vicinity of the combustion chamber of the intake port that is susceptible to heat during fuel combustion in the combustion chamber. Because of the inner surface, deposits accumulate at these locations.

  In so-called port injection type internal combustion engines that inject fuel into the intake system of an internal combustion engine to remove deposits from the back surface of the umbrella portion of the intake valve, toward the back surface of the intake valve umbrella portion and the inner surface of the intake port near the combustion chamber Some fuels are supplied by injection, and deposits adhering to these portions are washed away by the injected fuel.

In a so-called cylinder injection type internal combustion engine that directly injects fuel into the combustion chamber of the internal combustion engine, fuel is injected near the bottom dead center of the intake air before the intake valve closes in order to wash away the intake system deposit. This has also been proposed (see Patent Document 1). In this case, the fuel injected and supplied into the combustion chamber is caused to flow into the intake port due to the movement toward the top dead center side of the piston, and the deposit adhering to the rear surface of the umbrella portion of the intake valve is washed away.
JP 2001-289097 A

  As described above, the deposits can be removed to some extent by washing away the deposits adhering to the back surface of the umbrella portion of the intake valve and the inner surface of the intake port near the combustion chamber. However, even if the rear surface of the umbrella portion of the intake valve or the inner surface of the intake port near the combustion chamber is cleaned with fuel, the deposits cannot always be removed from these locations, and this is inconvenient. It can also be a cause.

  For example, an internal combustion engine provided with a maximum lift amount variable mechanism that makes the maximum lift amount of the intake valve variable, a multi-cylinder internal combustion engine having a plurality of cylinders, and a valve timing variable mechanism that makes the valve timing of the intake valve variable In an internal combustion engine, the following problems may occur due to the adhesion of the deposit.

[Internal combustion engine with variable maximum lift]
In the internal combustion engine, the maximum lift amount variable mechanism is controlled so that the maximum lift amount of the intake valve becomes a value suitable for the engine operating state. That is, as the engine load becomes lighter, the required intake air amount becomes smaller, so the maximum lift amount of the intake valve is made smaller and the intake air amount is reduced. By reducing the intake air amount by reducing the maximum lift amount of the intake valve in this way, it is not necessary to control the throttle valve to the closed side to reduce the intake air amount. It is possible to hold it every time. For this reason, it can suppress that the pump loss of an internal combustion engine increases with control of a throttle valve to the closed side as mentioned above, and the improvement in the fuel consumption of the same engine is prevented.

  If deposits adhere to the back of the intake valve umbrella or the inner surface of the intake port in the vicinity of the combustion chamber, the deposit becomes inflow resistance and the amount of intake air is insufficient relative to the required amount. The fuel ratio shifts from the appropriate value to the rich side. In particular, when the maximum lift amount of the intake valve is small and the intake air amount is small, the ratio of the shortage of the intake air amount due to the deposit to the total required intake air amount is large. The influence of the shortage of the intake air amount due to the deposit becomes large. For this reason, the amount of deviation from the appropriate value of the air-fuel ratio to the rich side due to the shortage of the intake air amount becomes large, and this inevitably leads to fluctuations in the rotation of the internal combustion engine and the like, resulting in unstable operation of the engine.

  When the engine is lightly loaded, the maximum lift amount is fixed in addition to maintaining the throttle valve on the open side and reducing the maximum lift amount of the intake valve to secure the required intake air amount as described above. In some cases, a necessary intake air amount is secured by controlling the opening of the throttle valve. In this case as well, since the amount of intake air is insufficient with respect to the required amount due to the adhesion of deposits, the same problem as described above also occurs.

[Multi-cylinder internal combustion engine]
In the internal combustion engine, an intake valve is provided for each intake port of each cylinder, and the back surface of the umbrella portion of these intake valves and the inner surface of the intake port near the combustion chamber are washed with fuel. However, the back surface of the umbrella portion of the intake valve of each cylinder and the inner surface of the intake port near the combustion chamber are not always cleaned uniformly between the cylinders, and the amount of deposit that cannot be removed by cleaning with fuel It is likely that the value will be different for each. Therefore, there are cylinders with a large amount of deposits and cylinders with a small amount of deposits, cylinders with deposits and cylinders with no deposits, and the amount of intake air caused by the deposits. The shortage also differs for each cylinder. For this reason, the amount of deviation from the appropriate value of the air-fuel ratio to the rich side is also different for each cylinder. Due to the variation in the air-fuel ratio among the cylinders, rotational fluctuations occur in the internal combustion engine, and the engine operates stably. It becomes difficult.

[Internal combustion engine with variable valve timing mechanism]
In the internal combustion engine, the valve timing variable mechanism is controlled so that the valve timing of the intake valve becomes suitable for the engine operating state. In other words, in this engine, air is sucked into the combustion chamber while pulsating during the intake stroke, so that the intake air amount is reduced as much as possible by closing the intake valve when the pressure in the intake port reaches the peak value. The engine output can be improved by increasing the number. For this reason, the valve timing of the intake valve is controlled so that the closing timing of the intake valve becomes the timing when the pressure in the intake port reaches the peak value.

  However, if deposits are attached to the rear surface of the umbrella portion of the intake valve or the inner surface of the intake port near the combustion chamber, the air flow area of the intake port is reduced by that amount, and the pulsation mode such as the pulsation wavelength of the intake air changes. As a result, the timing at which the pressure in the intake port peaks shifts to the advance side or the retard side. For this reason, the timing at which the pressure in the intake port reaches the peak value and the timing at which the intake valve closes deviate, and there is a possibility that the amount of intake air is reduced and the required value is insufficient. If the air-fuel ratio deviates from the appropriate value to the rich side due to the shortage of the intake air amount, the operation of the internal combustion engine becomes unstable and the operation of the engine becomes unstable.

  The present invention has been made in view of such circumstances, and an object thereof is an internal combustion engine capable of suppressing a decrease in drivability of the engine due to deposits attached to an intake system of the internal combustion engine. It is to provide an engine control device.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, the invention according to claim 1 is applied to a multi-cylinder internal combustion engine having a plurality of cylinders, and the maximum lift amount of the intake valve of the engine can be made variable for each cylinder. In a control apparatus for an internal combustion engine provided with a variable lift amount mechanism, detection means for detecting deposit adhesion to the intake system for each cylinder of the internal combustion engine, and deposit to the intake system for each cylinder detected by the detection means Control means for controlling the variable maximum lift amount mechanism so that the maximum lift amount of the intake valve is increased for each cylinder in response to an increase in the amount of adhering fuel.

Even if deposits are attached to the intake system and the amount of deposits is different for each cylinder, the maximum lift amount of the intake valve increases for each cylinder as the deposit amount of each cylinder increases. Thus, the intake air amount is increased for each cylinder. Therefore, due to the difference in the amount of deposit deposited on the intake system of each cylinder, the shortage of the intake air amount differs for each cylinder, and the deviation amount from the appropriate value of the air-fuel ratio to the rich side differs for each cylinder. It can be suppressed. Then, it is possible to suppress a decrease in the drivability of the internal combustion engine caused by such a variation in the air-fuel ratio among the cylinders and a reduction in the drivability of the internal combustion engine.

  According to a second aspect of the present invention, in the first aspect of the invention, the control means increases the maximum lift amount so that the larger the deposit adhesion amount, the larger the maximum lift amount increases. The maximum lift amount variable mechanism was controlled.

  The greater the amount of deposit deposited on the intake system, the greater the shortage of the intake air amount due to the deposit. For this reason, as the deposit amount increases as described above, the maximum lift amount of the intake valve is increased, so that the shortage of the intake air amount accompanying the deposit can be accurately suppressed. Accordingly, it is possible to suppress the difference in the shortage of the intake air amount for each cylinder and to appropriately suppress the variation in the air-fuel ratio among the cylinders.

According to a third aspect of the present invention, in the first or second aspect of the present invention, when the control means is at least in an engine operating region where the maximum lift amount is small, the deposit amount on the intake system for each cylinder. The maximum lift amount variable mechanism is controlled so that the maximum lift amount is increased for each cylinder in accordance with the increase in the amount.

  When the maximum lift amount of the intake valve is made small, the proportion of the shortage of the intake air amount due to deposit adhesion to the intake system becomes large in the total required intake air amount. For this reason, when the amount of deposit deposited on the intake system differs for each cylinder, the corresponding shortage of intake air amount for each cylinder also deviates greatly from each other, and the air-fuel ratio between the cylinders There is a risk that the variation will be large. However, by increasing the maximum lift amount of the intake valve for each cylinder based on the deposit amount for each cylinder, it is possible to suppress a significant shift in the intake air amount for each cylinder, and A large variation in the air-fuel ratio can also be suppressed.

[First Embodiment]
Hereinafter, an embodiment in which the present invention is applied to an in-cylinder spark ignition type four-cylinder engine mounted on an automobile will be described with reference to FIGS.

  In the engine 1 shown in FIG. 1, air is sucked into the combustion chambers 2 of the first to fourth cylinders # 1 to # 4 (only the first cylinder # 1 is shown) through the intake passage 3 and fuel is injected. Fuel is directly injected from the valve 4. When the air / fuel mixture is ignited by the spark plug 5, the air / fuel mixture burns, the piston 6 reciprocates, and the crankshaft 7 that is the output shaft of the engine 1 rotates. The air-fuel mixture after combustion is sent out from each combustion chamber 2 to the exhaust passage 8 as exhaust gas.

  The output adjustment of the engine 1 adjusts the opening degree (throttle opening degree) of the throttle valve 19 provided in the intake passage 3 when a homogeneous air-fuel mixture in which air and fuel are evenly mixed is burned at the stoichiometric air-fuel ratio. Is realized. That is, when the throttle opening is adjusted, the intake air amount of the engine 1 changes, the fuel injection amount is controlled in response to the change, and the amount of the air-fuel mixture filled in the combustion chamber 2 changes to output the engine 1 output. Will be adjusted. The throttle opening is adjusted based on the depression amount (accelerator depression amount) of the accelerator pedal 16 operated by the driver.

  In the engine 1, the combustion chamber 2 and the intake passage 3 are connected and cut off by the opening / closing operation of the intake valve 9, and the combustion chamber 2 and the exhaust passage 8 are connected and cut off by the opening / closing operation of the exhaust valve 10. . The intake valve 9 and the exhaust valve 10 are opened and closed in accordance with the rotation of the intake camshaft 11 and the exhaust camshaft 12 to which the rotation of the crankshaft 7 is transmitted.

  The intake camshaft 11 is provided with a variable valve timing mechanism 13 that adjusts the relative rotational phase of the intake camshaft 11 with respect to the crankshaft 7 to advance or retard the valve timing (opening period) of the intake valve 9. Yes. Further, between the intake camshaft 11 and the intake valve 9, a maximum lift amount variable mechanism 14 that continuously varies the maximum lift amount of the valve 9 is provided. The valve timing adjustment of the intake valve 9 by the variable valve timing mechanism 13 and the maximum lift amount adjustment of the intake valve 9 by the maximum lift amount variable mechanism 14 are uniformly performed for the intake valves 9 of the cylinders # 1 to # 4. Is done.

  The automobile is equipped with an electronic control unit 15 that controls the operation of the engine 1. Through this electronic control unit 15, fuel injection control of the engine 1, ignition timing control, throttle opening control, valve timing control of the intake valve 9 and maximum lift amount control are performed. Further, detection signals from various sensors described below are input to the electronic control unit 15.

A crank position sensor 25 that outputs a signal corresponding to the rotation of the crankshaft 7.
A cam position sensor 26 that outputs a signal corresponding to the rotational position of the intake camshaft 11.

An accelerator position sensor 17 that detects a depression amount (accelerator depression amount) of the accelerator pedal 16 that is depressed by the driver.
A throttle position sensor 20 that detects the throttle opening.

An air flow meter 18 that detects the flow rate of air passing through the intake passage 3.
A pressure sensor 22 capable of detecting, for each cylinder, the pressure in the intake port 21, which is a portion connected to the combustion chambers 2 of the first to fourth cylinders # 1 to # 4 in the intake passage 3.

An air-fuel ratio sensor 23 that detects the oxygen concentration of exhaust exhausted from the combustion chambers 2 of the first to fourth cylinders # 1 to # 4 for each cylinder and outputs a signal corresponding to the oxygen concentration.
An oxygen sensor that outputs a rich signal or lean signal based on the oxygen concentration in the exhaust after the exhaust discharged from the combustion chambers 2 of the first to fourth cylinders # 1 to # 4 merges in the exhaust passage 8 24.

Next, the fuel injection amount control of the engine 1 when the homogeneous air-fuel mixture is burned at the stoichiometric air-fuel ratio will be described.
In such fuel injection amount control, an injection amount command value is calculated based on the engine operating state such as the engine rotation speed and the engine load, and the fuel injection valve 4 is passed through the electronic control unit 15 so that an amount of fuel corresponding to the command value is injected. This is realized by performing the drive control.

  The engine speed is obtained based on a detection signal from the crank position sensor 25, and the engine load is obtained based on a parameter related to the intake air amount of the engine 1 and the engine speed. Parameters relating to the intake air amount of the engine 1 include the intake air amount obtained from the detection signal of the air flow meter 18, the accelerator depression amount obtained from the detection signal of the accelerator position sensor 17, and the detection signal of the throttle position sensor 20. The required throttle opening or the like is used.

  When the engine 1 is in a stable operating state after the warm-up is completed, air-fuel ratio feedback for accurately adjusting the average air-fuel ratio of the first to fourth cylinders # 1 to # 4 to the theoretical air-fuel ratio that is the target value Control is performed. In this air-fuel ratio feedback control, the fuel injection amount command value is corrected to increase or decrease depending on whether the average air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio.

  When the average air-fuel ratio is richer than the stoichiometric air-fuel ratio and the rich signal is output from the oxygen sensor 24, the feedback correction value FAF used for correcting the fuel injection amount command value is reduced. Then, based on the fuel injection amount command value corrected by the correction value FAF, the fuel injection valves 4 of the first to fourth cylinders # 1 to # 4 are driven and controlled, so that each cylinder # 1 to # 4 is controlled. The fuel injection amount is corrected to decrease, and the average air-fuel ratio is adjusted to the lean side.

  When the average air-fuel ratio is leaner than the stoichiometric air-fuel ratio and the lean signal is output from the oxygen sensor 24, the feedback correction value FAF is increased. Then, based on the fuel injection amount command value corrected by the correction value FAF, the fuel injection valves 4 of the first to fourth cylinders # 1 to # 4 are driven and controlled, so that each cylinder # 1 to # 4 is controlled. The fuel injection amount is corrected to increase, and the average air-fuel ratio is adjusted to the rich side.

  As described above, even if the average air-fuel ratio of all the cylinders # 1 to # 4 deviates from the stoichiometric air-fuel ratio for some reason by performing the air-fuel ratio feedback control, the deviation is corrected and the average air-fuel ratio becomes the stoichiometric air-fuel ratio. It can be adjusted to the exact position. Incidentally, as one of the causes that the average air-fuel ratio deviates from the stoichiometric air-fuel ratio, deposits adhere to the intake system of the engine 1, particularly the back surface of the umbrella portion of the intake valve 9, and the inner surface of the intake port 21 near the combustion chamber 2. It is conceivable that the deposits are not attached.

Next, the maximum lift amount control of the intake valve 9 and the opening degree control of the throttle valve 19 will be described.
The maximum lift amount of the intake valve 9 is controlled to a value suitable for the engine operating state by drivingly controlling the maximum lift amount variable mechanism 14 through the electronic control unit 15 based on the engine rotational speed, the engine load, and the like. For example, under the condition that the engine rotation speed is constant, the maximum lift of the intake valve 9 is increased in order to easily secure the intake air amount of the engine 1 as the engine load increases. This is because as the engine load increases, a larger engine output is required, and the amount of intake air required to obtain the output increases.

  On the other hand, the throttle valve 19 is controlled to be opened through the electronic control unit 15 as the accelerator depression amount indicating the driver's output request to the engine 1 increases. When the homogeneous air-fuel mixture is burned at the stoichiometric air-fuel ratio, the intake air amount of the engine 1 increases as the throttle opening increases, and the fuel injection amount increases accordingly, so the combustion chamber 2 is filled. The amount of air-fuel mixture increases and engine output increases. In this way, an engine output corresponding to the driver's output request for the engine 1 can be obtained.

  By the way, in an engine operation region where the required intake air amount is small, for example, in an engine low load region such as during idle operation, the throttle valve 19 is controlled to close to adjust the intake air amount to a required value. Is done. As a result, the intake resistance of the engine 1 increases, resulting in a pump loss, which adversely affects the improvement in fuel consumption of the engine 1. Therefore, in recent years, it has also been proposed that the throttle valve 19 is fixed on the open side when the engine is under a low load, and the intake air amount is adjusted by making the maximum lift amount of the intake valve 9 variable in the low lift region. In this case, since the increase in the intake resistance of the engine 1 due to the throttle valve 19 being controlled to the closed side is suppressed, the fuel efficiency of the engine 1 is improved.

  As described above, when the intake air amount is adjusted by varying the maximum lift amount of the intake valve 9 when the engine is under a low load, the maximum lift amount of the intake valve 9 is extremely small because the required intake air amount is small. The However, if deposits are attached to the intake system of the engine 1 in such a state and the air circulation area of the intake system is small, a shortage of the intake air amount accompanying the deposit attachment is required. Larger than the amount of intake air. For this reason, the shift to the rich side of the average air-fuel ratio of all the cylinders # 1 to # 4 due to the shortage of the intake air amount also increases.

  The deviation of the average air-fuel ratio to the rich side is suppressed by reducing the fuel injection amount by the feedback correction value FAF during the air-fuel ratio feedback control. However, even if the deviation of the average air-fuel ratio to the rich side can be suppressed by air-fuel ratio feedback control, it is inevitable that the amount of air-fuel mixture burned will be less than appropriate at this time. Insufficient air volume causes rotational fluctuations in the engine 1. Therefore, if the average air-fuel ratio deviates to the rich side, the engine 1 becomes unstable due to the rotational fluctuation of the engine 1 due to this.

  Note that the problem associated with deposit adhesion described above is limited to the engine 1 that secures a necessary intake air amount by varying the maximum lift amount of the intake valve 9 while individualizing the throttle valve 19 on the open side in the engine low load region. Not a thing. For example, the same problem occurs in an engine that secures a necessary intake air amount by controlling the opening degree of the throttle valve 19 while fixing the maximum lift amount of the intake valve 9 at a low engine load.

Here, a procedure for suppressing the unstable operation of the engine due to the adhesion of the deposit to the intake system will be described with reference to FIGS.
FIG. 2 is a flowchart showing an intake control routine for executing the maximum lift amount control of the intake valve 9 and the opening degree control of the throttle valve 19 when deposits adhere to the intake system. FIG. 3 is used to explain how the control modes of the maximum lift amount control and the throttle opening degree control change according to the presence or absence of deposits on the intake system when the engine is under a low load. It is a time chart.

  The intake control routine of FIG. 2 is executed through the electronic control unit 15 by, for example, a time interruption at every predetermined time. In this routine, it is first determined whether or not deposits are attached to the intake system (S101).

  Such a determination is made, for example, when one or more of the air-fuel ratios of the cylinders # 1 to # 4 obtained from the detection signal of the air-fuel ratio sensor 23 during the air-fuel ratio feedback control is set to a rich side by a predetermined amount or more from the theoretical air-fuel ratio. This is based on whether or not they are separated. That is, when any one or more of the air-fuel ratios of the cylinders # 1 to # 4 are made richer by a predetermined amount or more along with deposit adhesion to the intake system, the deposit adhesion amount to the intake system becomes the engine 1 Is estimated to have reached a predetermined value that adversely affects the intake air amount, and an affirmative determination is made in step S101.

  Further, it may be determined whether deposits are attached to the intake system based on the rotational fluctuation of the crankshaft 7. For example, the rotational fluctuation is obtained for each cylinder # 1 to # 4 when the crankshaft 7 passes a predetermined crank angle in the combustion stroke, and the angular velocity of the cylinder in the previous combustion stroke and the cylinder velocity in the current combustion stroke are It can be obtained by calculating the difference from the angular velocity. When deposits adhere to the intake system, the deposit amount differs for each of the cylinders # 1 to # 4. Therefore, the angular velocity also takes a different value for each of the cylinders # 1 to # 4. Therefore, the deposits cause a difference in the angular velocities of the cylinders # 1 to # 4, which leads to rotation fluctuations of the crankshaft 7. Therefore, whether deposits adhere to the intake system based on the rotation fluctuations or not. Can be judged.

  If a negative determination is made in step S101, the deposit is not adhered to the intake system so as to cause a problem. In this state, in order to improve the fuel consumption of the engine 1, the throttle opening is fixed to the open side value as shown in FIG. As shown in FIG. 3B, the intake air amount required for the low lift region is controlled. As described above, the throttle opening control and the maximum lift amount control suppress the increase in the intake resistance of the engine 1 and improve the fuel consumption.

  On the other hand, when an affirmative determination is made in step S101 (FIG. 2), the maximum lift amount of the intake valve 9 is fixed to a predetermined increase side value (S102), and the intake air amount is further adjusted to a required value. Throttle opening control is executed (S103).

  For example, when it is determined that the deposit adheres to the intake system as shown in FIG. 3A at the time of engine low load, the maximum lift amount of the intake valve 9 is increased after the timing t in FIG. As shown in FIG. 3B, the value is raised to a predetermined value on the increase side, and then fixed. By fixing the maximum lift amount to a predetermined value on the increase side in this way, it is possible to suppress the intake air amount from being insufficient with respect to the required amount due to the deposit adhering to the intake system. For this reason, the shift to the rich side of the average air-fuel ratio of all the cylinders # 1 to # 4 due to the shortage of the intake air amount is suppressed. Due to this shift, the engine 1 fluctuates and the engine operation becomes unstable. It is suppressed to become.

  In this way, by fixing the maximum lift amount to a predetermined value on the increase side, a shortage of the intake air amount is suppressed. Further, as described above, the excess amount of the intake air amount due to the maximum lift amount being fixed at a predetermined increase value is absorbed by adjusting the intake air amount by the throttle opening control. Therefore, after the timing t, the throttle opening changes to the closing side as shown in FIG. 3C, and the intake air amount should be adjusted to a required value in the opening side region of the closing side. To be controlled.

According to the embodiment described in detail above, the following effects can be obtained.
(1) Even if deposits are attached to the intake system of the engine 1, at that time, the maximum lift amount of the intake valve 9 is increased to a predetermined increase side value, and the intake air amount is increased. Therefore, the shortage of the intake air amount accompanying the deposit adhesion to the intake system is suppressed, and the average air-fuel ratio of all the cylinders # 1 to # 4 becomes the target value at the time of combustion at the stoichiometric air-fuel ratio of the homogeneous mixture accompanying the shortage. Deviation from a certain theoretical air-fuel ratio to the rich side is suppressed. And it can suppress that the fluctuation | variation of the rotation of the engine 1 resulting from this shift | offset | difference of an average air fuel ratio arises, and the operability of the engine 1 falls.

  (2) Further, the increase in the maximum lift amount as described above is executed even when the engine is under a low load such as an idling operation in which the required intake air amount is reduced. When the engine is under a low load, the required intake air amount is small, so the maximum lift amount of the intake valve 9 is set to a very small value. In this state, when deposits adhere to the intake system, the ratio of the shortage of the intake air amount to the entire required intake air amount becomes large, and the above average air-fuel ratio due to the shortage The problem of shifting to the rich side is also significant. However, since the shortage of the intake air amount is suppressed by the increase in the maximum lift amount described above, the above-described problems associated with the shortage of the intake air amount can be suppressed.

  (3) When the maximum lift amount is fixed to a predetermined increase value when deposits are attached to the intake system, the excess intake air amount is absorbed by adjusting the intake air amount by throttle opening control. Therefore, it is possible to suppress the intake air amount from being excessive and adjust the intake air amount to a required value.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 4 is a flowchart showing an intake control routine of the present embodiment. In this embodiment, when it is determined that deposits are attached to the intake system of the engine 1 (S201: YES), the maximum lift amount of the intake valve 9 is controlled to be increased by an amount corresponding to the deposit amount. (S202). The deposit adhesion amount can be estimated, for example, from the amount of deviation of the air-fuel ratio that is most deviated from the stoichiometric air-fuel ratio among the air-fuel ratios of the cylinders # 1 to # 4 to the rich side. Therefore, it is estimated that the deposit amount on the intake system increases as the air-fuel ratio shifts to the rich side, and the maximum lift amount of the intake valve 9 is controlled to increase.

  Here, the control mode of the maximum lift amount control of the intake valve 9 and the opening degree control of the throttle valve 19 when it is determined that deposits are attached at the time of low engine load will be described with reference to the time chart of FIG. To do.

  When it is determined that deposits are attached to the intake system as shown in FIG. 5 (a) at the time of engine low load (timing t2), the maximum lift amount of the intake valve 9 is shown in FIG. 5 (b). As shown in FIG. 4, the amount is increased by an amount corresponding to the amount of deposit deposited, and in this state, the required intake air amount is controlled. Such maximum lift amount control ensures a necessary intake air amount even when deposits are deposited, so that the throttle opening is maintained at a fixed value as shown in FIG. 5C. Therefore, as in the first embodiment, the throttle valve 19 is controlled to the closed side as the deposit adheres when the engine is under a low load, and the fuel efficiency improvement of the engine 1 is not hindered.

According to this embodiment, the following effects can be obtained.
(4) Even when deposits adhere to the intake system of the engine 1, at that time, the maximum lift amount of the intake valve 9 is controlled to be increased by an amount corresponding to the deposit amount. As the amount of deposit adhesion increases, the amount of intake air deficiency increases.However, by increasing the intake air amount by controlling the maximum lift as described above, the amount of intake air deficiency associated with deposit adhesion can be reduced. It can be accurately suppressed. Therefore, due to the shortage of the intake air amount accompanying the deposit adhesion to the intake system, the average air-fuel ratio of all the cylinders # 1 to # 4 from the stoichiometric air-fuel ratio when the homogeneous air-fuel mixture burns at the stoichiometric air-fuel ratio is the target value The shift to the rich side is suppressed. Then, it is possible to suppress a decrease in the drivability of the engine 1 due to the rotational fluctuation of the engine 1 due to the deviation in the average air-fuel ratio.

  (5) During engine low-load operation when deposits are attached, the amount of intake air required by the maximum lift amount control can be secured, so the throttle opening is fixed to the open side value. It becomes possible to leave. For this reason, it is not necessary to control the throttle valve 19 to the closed side when deposits are attached, and it is possible to suppress the improvement in fuel efficiency of the engine 1 from being controlled by the control to the closed side.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS.
In this embodiment, when the deposit amount on the intake system differs for each cylinder # 1 to # 4, the air-fuel ratio of each cylinder # 1 to # 4 approaches the average air-fuel ratio of all cylinders # 1 to # 4. Thus, the fuel injection amount is corrected for each cylinder so as to suppress variations in the air-fuel ratio among the cylinders # 1 to # 4. In this way, by suppressing the variation in the air-fuel ratio among the cylinders # 1 to # 4, it is possible to suppress the engine 1 from being unstable due to rotational fluctuations caused by the variation. Can do.

  FIG. 6 is a flowchart showing a fuel injection amount correction routine for executing the fuel injection amount correction described above. This fuel injection amount correction routine is executed through an electronic control unit 15 by, for example, an angle interruption every predetermined crank angle.

  In the fuel injection amount correction routine, it is first determined whether air-fuel ratio feedback control is being executed (S301). During the air-fuel ratio feedback control, the fuel injection amount of each cylinder # 1 to # 4 is uniformly increased or decreased based on the feedback correction value FAF so that the average air-fuel ratio of all the cylinders # 1 to # 4 becomes the stoichiometric air-fuel ratio. Is done. In this state, as shown in FIG. 7, the fuel injection amounts of the cylinders # 1 to # 4 are uniform, and the average air-fuel ratio of all the cylinders # 1 to # 4 becomes the stoichiometric air-fuel ratio.

  However, if the deposit amount on the intake system is different for each cylinder # 1 to # 4 and the intake air amount is different for each cylinder # 1 to # 4 at this time, as shown in FIG. The air-fuel ratio varies among the cylinders # 1 to # 4. In order to suppress such variations in the air-fuel ratio, the processes of steps S302 and S303 in the fuel injection amount correction routine (FIG. 6) are executed. In step S302, the deviation amount of the air-fuel ratio of each cylinder # 1 to # 4 with respect to the average air-fuel ratio (theoretical air-fuel ratio) is calculated. Subsequently, in step S303, the fuel injection amount is corrected for each cylinder # 1 to # 4 based on the amount of deviation calculated as described above so that the air-fuel ratio of each cylinder # 1 to # 4 approaches the average air-fuel ratio. Is done.

  That is, in the cylinder leaner than the average air-fuel ratio, the fuel injection amount is corrected to be increased corresponding to the amount of deviation of the air-fuel ratio from the average air-fuel ratio toward the lean side. The fuel injection amount increase correction amount at this time is increased as the amount of deviation of the air-fuel ratio toward the lean side increases. Further, in the cylinder richer than the average air-fuel ratio, the fuel injection amount is corrected to decrease in accordance with the amount of deviation of the air-fuel ratio with respect to the average air-fuel ratio toward the rich side. The fuel injection reduction correction amount at this time is increased as the deviation amount of the air-fuel ratio toward the rich side increases. Thus, by correcting the fuel injection amount for each cylinder # 1 to # 4, the air-fuel ratio of each cylinder # 1 to # 4 approaches the average air-fuel ratio (theoretical air-fuel ratio) of all cylinders # 1 to # 4. It is done.

  As the fuel injection amount correction for each cylinder # 1 to # 4, in addition to the fuel injection amount correction for each cylinder in S303, the fuel injection amount correction based on the feedback correction value FAF is also performed. . By these two fuel injection amount corrections, the fuel injection amounts of the respective cylinders # 1 to # 4 are corrected to the reduction side as the deposit adhesion amount in the respective cylinders # 1 to # 4 increases.

  When the fuel injection amount correction for each cylinder in S303 described above is completed for all cylinders # 1 to # 4, the fuel injection amount differs for each cylinder # 1 to # 4 as shown in FIG. Although the air-fuel ratio is uniform between the cylinders # 1 to # 4, the amount of the air-fuel mixture charged in the combustion chamber 2 varies among the cylinders. For this reason, variations occur in the output torque among the cylinders # 1 to # 4, and the engine 1 may vary in rotation due to the variations. In order to suppress such variations in output torque, the processing of steps S304 to S306 in the fuel injection amount correction routine (FIG. 6) is executed.

  That is, when it is determined in step S304 that the fuel injection amount correction described above has been completed for all cylinders # 1 to # 4, the output torque for each cylinder based on the operation of each cylinder # 1 to # 4 is calculated (S305). ). Such output torque can be calculated from, for example, rotational fluctuations of the crankshaft 7 based on the operation of the cylinders # 1 to # 4. As shown in FIG. Corresponding value. Then, in the subsequent step S306 (FIG. 6), torque reduction is performed in the cylinders with high output torque among the cylinders # 1 to # 4.

  For example, the amount of deviation of the output torque of each of the other cylinders relative to the output torque of the cylinder with the smallest output torque is obtained, and the output torque is reduced by controlling parameters other than the fuel injection amount in the other cylinders based on the amount of deviation. Is planned. The ignition timing and fuel injection timing can be considered as these parameters. By increasing at least one of the ignition timing and the fuel injection timing to the retard side as the deviation amount increases, the same output is achieved in a cylinder with high output torque. Torque can be reduced.

  Here, the output torque for each cylinder # 1 to # 4, the ignition timing retardation amount, and the fuel injection when the variation in output torque among the cylinders is suppressed by both the ignition timing retardation and the fuel injection timing retardation. FIG. 9 shows the timing retardation amount.

  As shown in the figure, the larger the deviation amount of the output torque of the other cylinders relative to the output torque of the cylinder with the smallest output torque, the greater the ignition timing retard amount and the fuel injection timing retard amount. Is done. As a result, the output torque of the other cylinders is reduced in accordance with the output torque of the cylinder having the smallest output torque, and the output torques of the cylinders # 1 to # 4 are made uniform. Therefore, when the fuel injection amount is corrected for each cylinder so that the air-fuel ratio of each cylinder # 1 to # 4 approaches the average air-fuel ratio, the engine 1 will fluctuate due to variations in output torque among the cylinders. Is suppressed.

  In order to make the output torque of each cylinder # 1 to # 4 uniform, the output torque of each cylinder is matched with that of the cylinder with the smallest output torque, but instead it is matched with the cylinder with the largest output torque. The output torque of other cylinders may be increased. In this case, as an increase in the output torque of each cylinder, for example, an advance of the ignition timing or the fuel injection timing is performed.

According to the embodiment described in detail above, the following effects can be obtained.
(6) Even if the deposit amount on the intake system differs for each cylinder # 1 to # 4, it is based on the fuel injection amount correction and feedback correction value FAF for each cylinder # 1 to # 4 in S303 described above. By the uniform fuel injection amount correction for all cylinders # 1 to # 4, the fuel injection amount reduction correction for each cylinder based on the deposit adhesion amount is performed. In such fuel injection amount reduction correction for each cylinder, the reduction correction amount is increased as the deposit adhesion amount increases. For this reason, it is possible to suppress the deviation amount of the air-fuel ratio from the initial state to the rich side from being different for each cylinder # 1 to # 4 due to the difference in the deposit amount of each cylinder # 1 to # 4. Can do. And it can suppress that the fluctuation | variation of rotation arises in the engine 1 resulting from the dispersion | variation in the air fuel ratio between such cylinders, and the operability of the engine 1 falls.

  (7) The fuel injection amount correction for each cylinder # 1 to # 4 in S303 described above is performed by changing the average air-fuel ratio to the theoretical air-fuel ratio by uniform fuel injection amount correction for all cylinders # 1 to # 4 in the air-fuel ratio feedback control. And then executed. Then, the fuel injection amount increase correction for the cylinders that are leaner than the average air-fuel ratio (theoretical air-fuel ratio) of all cylinders # 1 to # 4 by the fuel injection amount correction for each cylinder # 1 to # 4 in S303. The fuel injection amount reduction correction is performed for the cylinders that are richer than the average air-fuel ratio. Further, the increase / decrease correction amount of the fuel injection amount is increased as the deviation amount of the air-fuel ratios of the cylinders # 1 to # 4 with respect to the average air-fuel ratio increases. Therefore, the air-fuel ratio of each cylinder # 1 to # 4 is accurately brought close to the stoichiometric air-fuel ratio that is the target value of the average air-fuel ratio, and variation in the air-fuel ratio among the cylinders # 1 to # 4 is accurately suppressed. it can.

  (8) The fuel injection amount correction for each cylinder # 1 to # 4 in S303 and the uniform fuel injection amount correction for all cylinders # 1 to # 4 based on the feedback correction value FAF can be obtained by changing the required intake air amount. It is also executed when the engine is under a low load, such as during idling. At such a low engine load, the actual intake air amount is adjusted to a very small value because the required intake air amount is small. In this state, if deposits are attached to the intake system, the ratio of the shortage of the intake air amount to the total required intake air amount becomes large, and the deviation from the appropriate value of the air-fuel ratio becomes large. Will also be big. For this reason, when the deposit amount differs for each of the cylinders # 1 to # 4, the shortage of the intake air amount for each of the cylinders # 1 to # 4 is greatly shifted from each other. The variation in the air-fuel ratio between # 1 and # 4 may be large. However, the variation in the air-fuel ratio among the cylinders # 1 to # 4 can be suppressed by correcting the fuel injection amount.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
In the engine 1, the valve timing control of the intake valve 9 is executed so that the intake air amount is as much as possible and the engine output is improved. That is, in the intake stroke, air is sucked into the combustion chamber 2 while pulsating, so that the valve timing is variable through the electronic control unit 15 so that the intake valve 9 is closed when the pressure in the intake port 21 reaches the peak value. The mechanism 13 is driven, and as a result, as much intake air amount as possible is secured.

  However, when the air flow area of the intake port 21 is reduced due to deposits attached to the intake system, the timing at which the pressure in the intake port 21 reaches the peak value due to a change in the pulsation mode such as the pulsation wavelength of the intake air is advanced. Shift to the side or retarded side. In this embodiment, when the timing at which the pressure in the intake port 21 reaches the peak value shifts due to the deposit, the valve timing is corrected so that the closing timing of the intake valve 9 approaches the same timing. is there. By performing such valve timing correction, the timing at which the pressure in the intake port 21 reaches the peak value and the valve closing timing of the intake valve 9 are shifted, the intake air amount becomes insufficient, and the air-fuel ratio becomes richer than the appropriate value. It is possible to prevent the engine 1 from being unstable due to the rotational fluctuation of the engine 1 due to the deviation.

  FIG. 10 is a flowchart showing a valve timing correction routine for performing the valve timing correction. This valve timing correction routine is executed through an electronic control unit 15 by, for example, an angle interruption every predetermined crank angle. When it is determined in the valve timing correction routine that deposits are attached to the intake system (S401: YES), the actual timing (actual peak timing maxtR) at which the pressure in the intake port 21 reaches the peak value is determined by the pressure sensor. Based on the 22 detection signals, it is obtained for each cylinder # 1 to # 4 (S402).

  Here, the transition trend of the pressure in the intake port 21 of the predetermined cylinder in the intake stroke is shown in FIGS. In these drawings, the solid line indicates the transition of the pressure in the intake port 21 in a state where no deposit is attached, and the timing at which the valve closing timing Lc of the intake valve 9 reaches the peak value of the pressure (theoretical peak timing). maxtV). That is, normally, the valve timing control of the intake valve 9 is executed through the electronic control unit 15 so that the valve closing timing Lc becomes the theoretical peak timing maxtV.

  On the other hand, when deposit adheres to the cylinder, the pulsation mode of the pressure in the intake port 21 changes, and the pressure changes as indicated by a broken line in FIGS. 11 and 12, for example. The timing to reach the peak value shifts to the retard side (FIG. 11) or shifts to the advance side (FIG. 12). The actual peak timing maxtR in step S402 is obtained as the timing at which the pressure becomes highest in a predetermined range (Lc−TC to Lc + TC) including the valve closing timing Lc of the intake valve 9. As the predetermined range (Lc−TC to Lc + TC), for example, the maximum range in which the timing to reach the peak value of the pressure with the deposit adhesion can be adopted.

  In step S403 of the valve timing correction routine (FIG. 10), valve timing correction for correcting the valve timing of the intake valve 9 for each cylinder # 1 to # 4 based on the theoretical peak timing maxtV and the actual peak timing maxtR. A value tH is calculated. That is, the valve timing correction value tH is calculated for each cylinder # 1 to # 4 by subtracting the actual peak timing maxtR from the theoretical peak timing maxtV for each cylinder # 1 to # 4. When the valve timing correction value tH becomes a positive value, the valve timing of the intake valve 9 is advanced during the valve timing correction, and when the valve timing correction value tH becomes a negative value, The valve timing is retarded.

  When the actual peak timing maxtR shifts to the retard side with respect to the theoretical peak timing maxtV as shown in FIG. 11 as the deposit adheres, the valve timing correction value tH is a negative value, that is, the valve timing of the intake valve 9 is retarded. The value to be corrected. Further, when the actual peak timing maxtR is shifted to the advance side from the theoretical peak timing maxtV as shown in FIG. 12 as the deposit adheres, the valve timing correction value tH becomes a positive value, that is, the valve timing of the intake valve 9 is increased. This is the value to be advanced.

  In the subsequent step S404, an average correction value tHav that is an average value of the valve timing correction values tH for each of the cylinders # 1 to # 4 is calculated. The absolute value of the average correction value tHav increases as the actual peak timing maxtR of each cylinder # 1 to # 4 becomes farther from the theoretical peak timing maxtV (normal valve closing timing Lc of the intake valve 9). When the average correction value tHav is out of the allowable range (−DP to DP) (S405: NO), the valve timing of the intake valve 9 is uniformly corrected by the average correction value tHav for all cylinders # 1 to # 4. Is done. By this valve timing correction, the closing timing of the intake valve 9 is made closer to the timing (actual peak timing maxtR) at which the pressure in the intake port 21 reaches the peak value in each cylinder # 1 to # 4.

According to the embodiment described in detail above, the following effects can be obtained.
(9) When deposits are attached to the intake system, the valve timing of the valve 9 is corrected to advance and retard so that the closing timing of the intake valve 9 approaches the actual peak timing maxtR. It is possible to prevent the intake air amount from becoming excessively insufficient due to the deviation. As the intake air amount is insufficient, the air-fuel ratios of the cylinders # 1 to # 4 and the average air-fuel ratios of all the cylinders # 1 to # 4 are shifted from the appropriate values to the rich side, causing the engine 1 to fluctuate. A reduction in drivability can be suppressed.

  (10) The actual peak timing maxtR changes according to the amount of deposit deposited on the intake system. However, the absolute value of the average correction value tHav increases as the actual peak timing maxtR increases from the valve closing timing Lc (theoretical peak timing maxtV) of the intake valve 9, and the advance / retard angle correction of the valve timing increases. Is done. Accordingly, the valve closing timing of the intake valve 9 can be accurately brought close to the actual peak timing maxtR by the advance / retard angle correction of the valve timing.

[Other Embodiments]
Each said embodiment can also be changed as follows, for example.
In the first to fourth embodiments, the present invention is applied to the in-cylinder direct injection engine 1. However, the present invention may be applied to, for example, a port injection engine that injects fuel into the intake port 21. . In addition, in the direct injection type engine 1, deposits are likely to be attached to the intake system, and various problems due to a shortage of intake air due to the deposits are likely to occur. To be done.

  In the first embodiment, the present invention is applied to the engine 1 that secures a necessary intake air amount by adjusting the maximum lift amount of the intake valve 9 while fixing the throttle valve 19 to the open side at a low engine load. The present invention may be applied to the engine 1 that secures a necessary intake air amount by another method. For example, the present invention may be applied to an engine that secures a necessary intake air amount by controlling the opening degree of the throttle valve 19 while fixing the maximum lift amount of the intake valve 9 at a low engine load.

  In the second embodiment, the maximum lift amount control when deposits adhere to the intake system is uniformly performed for each cylinder # 1 to # 4. However, the maximum lift amount control is performed individually for each cylinder # 1 to # 4. May be. In this case, as a maximum lift amount variable mechanism that controls the maximum lift amount of the intake valve 9 for each of the cylinders # 1 to # 4, the intake valve 9 may be a so-called electromagnetically driven valve that is controlled to open and close by an electromagnetic force, for example. It is done. The electromagnetically driven valve (intake valve 9) is individually driven for each cylinder # 1 to # 4 through the electronic control unit 15 so that the maximum lift amount is controlled to be increased for each cylinder # 1 to # 4. Be controlled. In such maximum lift amount control for each cylinder # 1 to # 4, it is preferable to increase the maximum lift amount as the deposit adhesion amount of each cylinder # 1 to # 4 increases. It should be noted that the deposit amount of each cylinder # 1 to # 4 can be estimated based on the air-fuel ratio of each cylinder # 1 to # 4 and the rotation fluctuation of the crankshaft based on the operation of each cylinder # 1 to # 4. it can.

  In the third embodiment, in order to suppress variation in the air-fuel ratio among the cylinders # 1 to # 4, each cylinder # 1 is set so that the air-fuel ratio approaches the average air-fuel ratio of all the cylinders # 1 to # 4. Although the fuel injection amount is corrected every .about.4, the present invention is not limited to this. For example, the intake valve 9 can be changed to the above-described electromagnetically driven valve so that the maximum lift amount can be individually changed for each cylinder # 1 to # 4, and the air-fuel ratio of each cylinder # 1 to # 4 approaches the average air-fuel ratio. The maximum lift amount may be controlled for each cylinder. In this case as well, as described above, it is preferable to increase the maximum lift amount as the deposit amount of each cylinder # 1 to # 4 increases. Accordingly, it is possible to suppress the deposit amount from being different for each of the cylinders # 1 to # 4 and the intake air amount from being insufficient for each of the cylinders. Thus, the variation in the air-fuel ratio can be accurately suppressed. Since the maximum lift amount control for each of the cylinders # 1 to # 4 at the time of deposit attachment is executed even at a low engine load when the required intake air amount is reduced, the cylinders # 1 to # 4 are at that time. The occurrence of large variations in the air-fuel ratio can be suppressed.

  In the third embodiment, the ignition timing retard or fuel injection timing retard is performed on the cylinder with high output torque to reduce the output torque, but other parameters such as the internal EGR amount are used as parameters for reducing the output torque. May be used. When the internal EGR amount is used, for example, the intake valve 9 is constituted by the above-described electromagnetically driven valve so that the valve timing of the intake valve 9 can be made variable for each cylinder # 1 to # 4. For cylinders with high output torque, the valve timing of the intake valve 9 is advanced to increase the valve overlap, and the output torque is reduced by increasing the internal EGR amount.

  In the fourth embodiment, as the valve timing control mechanism for controlling the valve timing of the intake valve 9 for each cylinder # 1 to # 4, the intake valve 9 is, for example, the above-described electromagnetically driven valve, and for each cylinder # 1 to # 4 Alternatively, the valve timing correction may be performed so that the closing timing of the intake valve 9 approaches the actual peak timing maxtR. In this case, valve timing correction of the intake valve 9 is performed for each cylinder # 1 to # 4 using the valve timing correction value tH for each cylinder # 1 to # 4.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole cylinder injection spark ignition type 4 cylinder engine to which the control apparatus of 1st Embodiment is applied. 5 is a flowchart showing an execution procedure of intake valve maximum lift amount control and throttle valve opening control when deposits adhere to the intake system in the first embodiment. (A) to (c) show how the control modes of the maximum lift amount control and the throttle opening degree control change in accordance with the presence or absence of deposit adhesion to the intake system at the time of engine low load in the first embodiment. A time chart used to explain what to do. In 2nd Embodiment, the time chart which shows the execution procedure of the maximum lift amount control of an intake valve when a deposit adheres to an intake system. (A) to (c) show how the control modes of the maximum lift amount control and the throttle opening degree control change according to the presence or absence of deposits on the intake system when the engine is under a low load in the second embodiment. A time chart used to explain what to do. In 3rd Embodiment, the flowchart which shows the fuel injection amount correction | amendment procedure when a deposit adheres to an intake system. The graph which shows the fuel injection amount and air fuel ratio of each cylinder in air-fuel ratio feedback control, and the average air fuel ratio of all the cylinders. The graph which shows the fuel injection amount of each cylinder when the said fuel injection amount correction | amendment is performed with the adhesion of the deposit to an intake system, and an average air fuel ratio of all the cylinders. Fuel injection amount for each cylinder, output torque, ignition timing retard amount when suppressing the variation in output torque of each cylinder when the above fuel injection amount correction is executed in accordance with deposit adhesion to the intake system, and The graph which shows fuel injection timing retard amount. The flowchart which shows the valve timing correction | amendment procedure of an intake valve when a deposit adheres to the intake system in 4th Embodiment. The time chart which shows the transition tendency of the pressure in the intake port of a predetermined cylinder in an intake stroke. The time chart which shows the transition tendency of the pressure in the intake port of a predetermined cylinder in an intake stroke.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, # 1- # 4 ... First-fourth cylinder, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust Passage, 9 ... intake valve, 10 ... exhaust valve, 11 ... intake camshaft, 12 ... exhaust camshaft, 13 ... variable valve timing mechanism, 14 ... maximum lift variable mechanism, 15 ... electronic control device (detection means, control means) ), 16 ... Accelerator pedal, 17 ... Accelerator position sensor, 18 ... Air flow meter, 19 ... Throttle valve, 20 ... Throttle position sensor, 21 ... Intake port, 22 ... Pressure sensor, 23 ... Air-fuel ratio sensor (detection means), 24 ... oxygen sensor, 25 ... crank position sensor (detection means), 26 ... cam position sensor (detection means).

Claims (3)

In a control apparatus for an internal combustion engine, which is applied to a multi-cylinder internal combustion engine having a plurality of cylinders and includes a maximum lift amount variable mechanism capable of varying the maximum lift amount of the intake valve of the engine for each cylinder.
Detecting means for detecting adhesion of deposits to the intake system for each cylinder of the internal combustion engine;
The maximum lift amount variable mechanism is controlled so that the maximum lift amount of the intake valve is increased for each cylinder in accordance with an increase in the amount of deposit adhering to the intake system for each cylinder detected by the detection means. Control means;
A control device for an internal combustion engine. 2. The internal combustion engine according to claim 1, wherein when the maximum lift amount is increased, the control unit controls the maximum lift amount variable mechanism such that the increase amount of the maximum lift amount increases as the deposit amount increases. Control device. The control means is configured to increase the maximum lift amount for each cylinder in accordance with an increase in deposit amount on the intake system for each cylinder when at least in the engine operation region where the maximum lift amount is small. The control apparatus for an internal combustion engine according to claim 1, wherein the maximum lift amount variable mechanism is controlled.

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