JP2012031869A - Control system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of more certainly suppressing a malfunction such as seizure on a sliding surface while further reducing a workload on an ECU even if lubricating oil in an internal combustion engine is diluted with injected fuel.SOLUTION: A control system includes an output improvement mechanism improving the output of the internal combustion engine based on a mechanistic operation. When a degree of oil dilution in the internal combustion engine is higher than a threshold (step S102), operation to improve the output of the internal combustion engine by the output improvement mechanism is stopped (step S104).

Description

  The present invention relates to a control system for an internal combustion engine having an output improvement mechanism for improving the engine output of the internal combustion engine based on a mechanical operation.

  When the internal combustion engine is cold, the temperature in the cylinder is low, so the fuel is difficult to atomize, and the fuel injected from the fuel injection valve may remain attached to the top surface of the piston or the cylinder side wall.

  Of the fuel adhering to the top surface of the piston and the cylinder side wall, in particular, the fuel adhering to the piston top surface is gradually atomized during subsequent engine combustion, and may be incompletely combusted and discharged from the cylinder. In this case, exhaust characteristics may be deteriorated, such as generation of black smoke and increase in unburned fuel components.

  Further, of the above adhering fuel, the fuel adhering to the cylinder side wall is mixed with the lubricating oil adhering to the cylinder side wall for piston lubrication. As a result, dilution of the lubricating oil with fuel, so-called oil dilution occurs. The lubricating oil in the cylinder diluted with fuel is scraped off along with the reciprocating motion of the piston and returned to the oil pan, and is further used for lubricating the internal combustion engine.

  As described above, since the viscosity of the fuel diluted by oil dilution decreases, there is a possibility that sufficient lubrication performance cannot be exhibited particularly when the oil temperature is increased and the viscosity is further decreased.

  On the other hand, at the time of cold start, the fuel injection timing may be set during the intake stroke, and the period from fuel injection to ignition may be ensured as long as possible to promote atomization of the injected fuel. However, even in such a case, it is difficult to completely eliminate the above-mentioned fuel adhesion, and some fuels remain attached to the cylinder after engine combustion without being used for combustion. It remains.

  By the way, in recent internal combustion engines, the maximum combustion pressure has been increased by the progress of fuel injection technology and the like. Recently, in order to improve fuel efficiency, friction has been reduced by using low-viscosity lubricating oil, and the width of sliding parts such as bearings has been narrowed to reduce friction. To be done.

  Such an increase in the maximum combustion pressure, a lower viscosity of the lubricating oil, and a narrower bearing are effective in terms of improving the performance and fuel consumption of the internal combustion engine. The load (load due to combustion pressure) is increased.

  In such a severe environment with respect to lubrication, if the viscosity of the lubricating oil further decreases due to the oil dilution described above, the lubrication at each sliding portion becomes insufficient, resulting in inconvenience such as bearing seizure. Easy situation. In particular, since a large combustion load acts on a mechanism constituting an output system such as a connecting rod bearing and a crankshaft, there is a high possibility that seizure will occur.

In relation to this, the required rotation time per unit crank angle or the operation parameter of the internal combustion engine correlated therewith is detected, and based on the detected required rotation time or operation parameter, combustion is performed before fuel is injected by the fuel injection valve. There is a known technique for determining whether or not the fuel has been used and detecting oil dilution by fuel when it is determined that the combustion before the injection has been performed. In this technique, when oil dilution is detected, control is performed to suppress output formation of the internal combustion engine (see Patent Document 1).

  Further, an invention has been proposed in which the dilution amount of the engine oil diluted by the post-injected fuel and the evaporation amount of the fuel evaporated from the engine oil are calculated, and based on these, the dilution state of the engine oil is estimated. (See Patent Document 2).

  Further, an invention is known that reduces the output of an internal combustion engine when the amount of lubricating oil exceeds a predetermined value, that is, when the lubricating oil is diluted with fuel and the sliding portion such as a bearing becomes insufficiently lubricated. It is. In the present invention, for example, by controlling to lower the maximum combustion pressure, the combustion load acting on the sliding portion such as the bearing at the maximum combustion pressure is suppressed, and seizure of the connecting rod bearing or the like is prevented (patent document) 3).

  For example, in the invention according to Patent Document 3, when the lubricating oil is diluted with fuel and the sliding portion such as a bearing becomes insufficiently lubricated, an internal combustion engine is used by using a control map having a low maximum combustion pressure. This is a software measure that controls the amount of fuel injection. This complicates control when dealing with oil dilution, and increases the number of necessary maps and increases the use capacity of the memory, resulting in an inconvenience that the burden on the ECU increases.

JP-A-2005-346441 Japanese Utility Model Publication No. 2007-2688 JP 2006-283709 A

  The present invention has been made in view of the above circumstances, and its object is to suppress an increase in the burden on the ECU even when the lubricating oil in the internal combustion engine is diluted with the injected fuel. It is to provide a technique that can more reliably suppress inconveniences such as seizure in the sliding portion.

  The present invention for achieving the above object has an output improving mechanism for improving the output of the internal combustion engine based on the mechanical operation, and when the oil dilution in the internal combustion engine becomes excessive, the output is increased. The biggest feature is to stop the operation by the improvement mechanism.

More specifically, an output improvement mechanism that improves the output of the internal combustion engine based on a mechanical operation;
Oil dilution detection means for detecting the degree of dilution of the engine oil in the internal combustion engine with fuel;
With
When the degree of dilution of the engine oil detected by the oil dilution detection means is greater than a predetermined degree,
The output improvement of the internal combustion engine by the output improvement mechanism is stopped.

Here, when so-called oil dilution occurs in which the engine oil is diluted by the injected fuel, as described above, it becomes difficult to secure the oil film thickness at each sliding portion of the internal combustion engine. Insufficient lubrication is likely to cause inconveniences such as seizure. In particular, since a large combustion load acts on the sliding portion of a mechanism that constitutes an output system such as a connecting rod bearing and a crankshaft (hereinafter also referred to as “output system construction mechanism”), there is a possibility that seizure or the like may occur. Get higher.

  On the other hand, when oil dilution is detected, it is conceivable to switch the map for determining the fuel injection amount in the cylinder and reduce the output of the internal combustion engine by a soft method. If it does so, the load which acts on each sliding part of an output system mechanism can be reduced, and generation | occurrence | production of seizure etc. can be suppressed. However, when the output of the internal combustion engine is reduced by a soft method, the control becomes complicated and the scale of the map to be stored in the memory increases, which may increase the burden on the ECU.

  Therefore, the present invention includes an output improvement mechanism that improves the output of the internal combustion engine based on a mechanical operation, and an oil dilution detection unit that detects the degree of dilution of the engine oil in the internal combustion engine with fuel. If the degree of dilution of the engine oil detected by the oil dilution detection means is greater than a predetermined degree, the output improvement of the internal combustion engine by the output improvement mechanism is stopped.

  As a result, while suppressing an increase in the burden on the ECU, the output of the internal combustion engine can be reduced, and the load acting on the output system constituting mechanism such as the connecting rod and the crankshaft can be reduced. Therefore, an increase in sliding resistance due to insufficient lubrication in each sliding portion of the output system constituting mechanism can be suppressed, and a decrease in reliability of each sliding portion can be suppressed.

  In the above description, the oil dilution detection means may be a viscosity sensor that directly measures the viscosity of the engine oil. Alternatively, the fuel injection amount and the amount of fuel remaining in the cylinder may be estimated from the operating state of the internal combustion engine, and the degree of oil dilution may be estimated based on the estimated fuel injection amount.

  In addition, the predetermined degree in the above is the degree of oil dilution as a threshold at which, if the degree of oil dilution is greater than this, there is a risk of seizure or the like due to insufficient lubricity in each sliding part of the internal combustion engine. Alternatively, it may be obtained in advance by experiments or the like.

  In the present invention, the output improvement mechanism can switch the cam profile of the valve mechanism in the internal combustion engine between a high lift profile and a low lift profile, and switches the cam profile to the high lift profile. Thus, a cam profile switching mechanism for improving the output of the internal combustion engine may be used.

  Here, the cam profile switching mechanism may have two types of cams, for example, a high lift cam having a high lift profile and a low lift cam having a low lift profile. That is, a mechanism that allows selection of which one of the two types of cams is used to drive the valve may be used.

  In this case, when it is determined that the degree of oil dilution is greater than the predetermined degree, the cam profile switching mechanism switches the cam used for driving the valve from the high lift cam to the low lift cam. As a result, the cam profile is changed from the high lift profile to the low lift profile to reduce the lift amount of the valve. As a result, the engine output can be reduced, so that the load acting on each sliding portion of the output system constituting mechanism of the internal combustion engine can be reduced.

Further, the cam of the valve mechanism opens the valve against the urging force, and the load acting on the cam and the valve can be reduced by changing the high lift profile to the low lift profile. . As a result, the increase in the output of the internal combustion engine can be stopped while suppressing an increase in the burden on the ECU, and the load acting on each sliding portion of the output system constituting mechanism of the internal combustion engine and the output improving mechanism itself. The load can be reduced, and the occurrence of inconvenience such as seizure can be suppressed.

  Further, in the present invention, the output improvement mechanism can change the rotational phase of the cam of the valve mechanism in the internal combustion engine, and the output of the internal combustion engine can be changed by changing the rotational phase of the cam and changing the valve timing. A variable valve mechanism to be improved may be used.

  In this case, the state in which the output improving mechanism is improving the output is possible as long as the valve timing at which the output of the internal combustion engine becomes higher than a predetermined threshold output (hereinafter referred to as “high output valve timing”). The cam phase is adjusted by the variable valve mechanism. When the degree of oil dilution exceeds a predetermined level, the variable valve mechanism returns the cam phase to the normal state, so that the valve timing deviates from the high output valve timing, and the engine output is Below the threshold output. Here, the predetermined threshold output is when the output of the internal combustion engine is higher than this, and when the oil dilution degree is higher than the predetermined degree, there is a problem such as seizure in the sliding portion of the output system constituting mechanism. The engine output is considered to be possibly generated, and may be obtained in advance through experiments or the like.

  According to this, the simple control of changing the rotational phase of the cam by the variable valve mechanism can stop the improvement of the output of the internal combustion engine and reduce the engine output while suppressing the burden on the ECU. As a result, the load acting on each sliding portion of the output system constituting mechanism of the internal combustion engine can be reduced, and the occurrence of inconvenience such as seizure can be suppressed.

According to the present invention, there is further provided a transmission mechanism that is disposed between the cam and the valve of the valve mechanism in the internal combustion engine and swings based on the action of the cam and transmits the swing motion to the valve. Prepared,
The output enhancement mechanism is
A valve opening period changing mechanism for improving the output of the internal combustion engine by changing the valve opening period and the lift amount of the valve by changing the timing and amplitude of swinging of the transmission mechanism.

  In this case, the state in which the output of the internal combustion engine is improved is that the valve opening period and the lift amount of the valve in the internal combustion engine are increased, and the valve opening period changing mechanism is set so that the engine output becomes larger than the aforementioned threshold output. Is the state in which the phase and amplitude of the oscillation of the transmission mechanism are set. When the degree of oil dilution is equal to or greater than a predetermined degree, the valve opening period changing mechanism returns the swinging phase of the transmission mechanism to the normal state, and the swinging amplitude is reduced. As a result, the valve opening period is shortened, the lift amount is reduced, and the engine output is reduced below the threshold output. Therefore, it is possible to reduce the load acting on the sliding portion of the output system constituting mechanism of the internal combustion engine while suppressing the burden on the ECU. In addition, the cam opens the valve against the urging force via the transmission mechanism, and acts on the cam, the valve, and the valve opening period changing mechanism itself by reducing the valve lift amount and the valve opening period. Load to be reduced.

  In the present invention, the output improvement mechanism may be a variable compression ratio mechanism that improves the output of the internal combustion engine by increasing the compression ratio by reducing the volume of the combustion chamber in the internal combustion engine.

In this case, the state in which the output of the internal combustion engine is improved is a state in which the variable compression ratio mechanism sets the compression ratio in the internal combustion engine to the high compression ratio side so that the output of the internal combustion engine is greater than the threshold output. It is. If the degree of oil dilution is determined to be greater than or equal to the predetermined degree, the variable compression ratio mechanism stops the improvement of the output of the internal combustion engine by returning the compression ratio to the normal compression ratio, and the engine output is the threshold output. Reduce to: Therefore, it is possible to reduce the load acting on the sliding portion of the output system constituting mechanism of the internal combustion engine while suppressing the burden on the ECU. At this time, since the combustion pressure is reduced, the load acting on the variable compression ratio mechanism itself that mechanically controls the volume of the combustion chamber is also reduced.

  According to this, the simple control of changing the compression ratio of the internal combustion engine can stop the improvement of the output of the internal combustion engine while suppressing the burden on the ECU, and the sliding of the output system constituting mechanism of the internal combustion engine can be stopped. The load acting on the moving part can be reduced. In addition, the load acting on the variable compression ratio mechanism itself can be reduced, and the occurrence of inconvenience such as seizure can be suppressed.

In the present invention, the output improvement mechanism is
It may be a variable nozzle mechanism that improves the output of the internal combustion engine by changing the opening degree of the nozzle vane provided in the turbocharger turbine in the internal combustion engine to the closed side.

  In this case, the state in which the output of the internal combustion engine is improved is that the variable nozzle mechanism increases the supercharging pressure by controlling the opening degree of the nozzle vane of the supercharger to the closed side, and the engine output exceeds the threshold output. It is in a state of trying to increase. If it is determined that the degree of oil dilution is greater than or equal to the predetermined degree, the output of the internal combustion engine is stopped by returning the nozzle vane opening to the normal opening, and the engine output is below the threshold output. To lower.

  According to this, with the simple control of changing the opening degree of the nozzle vane by the variable nozzle mechanism, it is possible to stop the improvement of the output of the internal combustion engine while suppressing the burden on the ECU, and the output system configuration of the internal combustion engine The load acting on the sliding part of the mechanism can be reduced. At this time, when the engine output is reduced, the turbine inlet pressure in the exhaust system is also reduced, so that the load acting on the variable nozzle mechanism itself including the nozzle vanes can be reduced. As a result, it is possible to more reliably suppress the occurrence of inconvenience such as image sticking.

In the present invention, the output improvement mechanism is
By temporarily closing the intake control valve provided in the intake passage in the internal combustion engine and performing the impulse supercharging to open the intake control valve while the intake valve is open, the output of the internal combustion engine is reduced. An impulse charge mechanism to improve may be used.

  In this case, the state of improving the output of the internal combustion engine means the following. That is, the intake control valve provided in the intake passage of the internal combustion engine is temporarily closed in synchronization with the opening and closing of the intake valve, and the impulse charge is performed to open the intake control valve while the intake valve is open, The engine output is set to be larger than the threshold output. If it is determined that the degree of oil dilution is greater than or equal to a predetermined degree, the impulse supercharging is stopped and the engine output is reduced to a threshold output or less.

  According to this, it is possible to stop the improvement of the output of the internal combustion engine while suppressing the burden on the ECU with a simple control of stopping the impulse supercharging, and the sliding part of the output system constituting mechanism of the internal combustion engine The load acting on the can be reduced. At this time, by stopping the impulse supercharging, the negative pressure generated in the intake passage between the intake control valve and the intake valve is also reduced, so that the load acting on the impulse charge mechanism itself can be reduced. As a result, it is possible to more reliably suppress the occurrence of inconvenience such as image sticking.

  Further, in the present invention, when the degree of dilution of the engine oil detected by the oil dilution detecting means is larger than a predetermined degree, the engine speed of the internal combustion engine is limited to a predetermined low speed range. May be.

  Then, when the degree of oil dilution is greater than the predetermined degree, the load on the output system configuration mechanism can be further reduced by limiting the engine speed, resulting in inconvenience such as seizure of each sliding part. Can be more reliably suppressed.

  The means for solving the problems in the present invention can be used in combination as much as possible.

  In the present invention, even when the lubricating oil in the internal combustion engine is diluted with the injected fuel, it is possible to more reliably suppress inconveniences such as seizure at each sliding portion of the internal combustion engine while suppressing an increase in the burden on the ECU. can do.

It is a figure which shows schematic structure of the valve operating mechanism which has a cam switching mechanism in Example 1 of this invention, a lubrication system, and a control system. It is a flowchart about the mechanism change routine at the time of oil dilution in Example 1 of this invention. It is a flowchart about the mechanism change routine 2 at the time of oil dilution in this Example 2 of this invention. It is a figure which shows schematic structure of the rocking | swiveling type variable valve mechanism in Example 3 of this invention. It is a graph which shows the example of the change amount of the lift amount and valve opening period of an intake valve by the rocking | fluctuation type variable valve mechanism in Example 3 of this invention. It is a flowchart about the mechanism change routine 3 at the time of oil dilution in Example 3 of this invention. It is a figure which shows schematic structure of the internal combustion engine provided with the variable compression ratio mechanism in Example 4 of this invention. It is a flowchart about the mechanism change routine 4 at the time of oil dilution in Example 4 of this invention. It is a figure which shows the state at the time of nozzle opening of the variable nozzle mechanism in Example 5 of this invention. It is a figure which shows the state at the time of the nozzle valve closing of the variable nozzle mechanism in Example 5 of this invention. It is a flowchart about the mechanism change routine 5 at the time of oil dilution in Example 5 of this invention. It is a figure which shows schematic structure of the impulse charge mechanism periphery part of the internal combustion engine in Example 6 of this invention. It is a flowchart about the mechanism change routine 6 at the time of oil dilution in Example 6 of this invention.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings.

[Example 1]
FIG. 1 shows a schematic configuration of a valve operating mechanism having a cam switching mechanism, a lubrication system, and a control system in this embodiment. In the camshaft 3 of the valve operating mechanism 10 in the present embodiment, two types of first cams 1 and second cams 2 are prepared for each valve so that the lift amount of the intake valve 6 can be changed. Then, the lift amount of the intake valve 6 can be changed by selectively engaging either the first cam 1 or the second cam 2 by moving the rocker arm 4 parallel to the cam shaft 3. Yes.

Here, the first cam 1 has a high lift profile that increases the lift amount of the intake valve 6, and the second cam 2 has a low lift profile that decreases the lift amount of the intake valve 6. .

The valve operating mechanism 10 is provided with a lubricating oil pump 13 driven by a crankshaft 15, and supplies engine oil to each part of the internal combustion engine and a hydraulic control valve (hereinafter referred to as OCV) 11.
Engine oil as pressure oil is supplied to a hydraulic cylinder 17 that moves the rocker arm 4 in the axial direction via Further, engine oil as lubricating oil is pumped to each part of the internal combustion engine by the lubricating oil pump 13 and is returned to the oil pan 14 after being used for lubricating each part. The oil passage 12 at that time is provided with a viscosity sensor 19 so that the viscosity of the engine oil can be detected. In this embodiment, the viscosity of the engine oil is detected by the viscosity sensor 19, and the degree of dilution of the engine oil is obtained from the viscosity.

Reference numeral 18 denotes an electronic control unit (ECU) that performs basic control such as fuel injection and ignition timing control of the internal combustion engine. The ECU 18 is constituted by a digital computer, and performs valve lift amount control in this embodiment in addition to the basic control of the internal combustion engine. The ECU 18 is connected to the actuator of the OCV 11 via a drive circuit (not shown) and controls the operation of the OCV 11.

  In the cam switching mechanism 10a in the present embodiment, when the internal combustion engine is operating at a high load, the OCV 11 is controlled by the ECU 18 so that the rocker arm 4 and the first cam 1 are engaged. 17 is controlled. When the internal combustion engine is operated at a low load, the ECU 18 controls the OCV 11 so that the hydraulic cylinder 17 is controlled so that the rocker arm 4 and the second cam 2 are engaged.

  As a result, an optimal valve lift amount can be obtained depending on the operating state of the internal combustion engine, and finer control of the output characteristics of the internal combustion engine is possible.

  Next, in the present embodiment, when the internal combustion engine is operating at a high load, that is, when the OCV 11 is controlled so that the rocker arm 4 and the first cam 1 are engaged, oil dilution occurs. Think. In this case, the lubrication performance by the engine oil is lowered, and there is a case in which the rotational load on the crankshaft 15 or the like increases or the durability is lowered. Further, since the lubrication performance between the first cam 1 and the rocker arm 4 is lowered, the durability of the valve mechanism 10 may also be lowered.

  Therefore, in this embodiment, when oil dilution is detected in the above-described state, the OCV 11 causes the cam engaged with the rocker arm 4 to be moved from the first cam 1 having the high lift profile to the low lift. It was decided to switch to the second cam 2 having a profile.

  By doing so, first, the amount of intake air is reduced by reducing the lift amount of the intake valve 6 and the combustion pressure in the cylinder is lowered, so the load on the output system mechanism such as the crankshaft 15 is reduced. Further, the intake valve 6 is normally urged to the valve closing side by a valve spring (not shown), and is opened against the urging force by the action of the first cam 1 or the second cam 2. As the lift amount increases, the load acting on the cam and the intake valve 6 increases. In this embodiment, when the second cam 2 is selected, the lift amount is smaller than when the first cam 1 is selected, so that the load acting on the second cam 2, the rocker arm 4 and the intake valve 6 is reduced. And the durability of the cam switching mechanism 10a itself can be improved.

  FIG. 2 shows a flowchart of a mechanism change routine at the time of oil dilution in the present embodiment. This routine is a program stored in the ROM in the ECU 18, and is a routine executed by the ECU 18 at predetermined intervals during operation of the internal combustion engine.

  When this routine is executed, first, in S101, the oil dilution degree is acquired. Specifically, the output signal of the viscosity sensor 19 is taken into the ECU 18. When the processing of S101 ends, the process proceeds to S102.

  In S102, it is determined whether or not the oil dilution degree acquired in S101 is larger than a predetermined threshold value. When the oil dilution degree is larger than this, this threshold is considered to be a risk that sufficient lubrication performance cannot be obtained at each sliding portion of the internal combustion engine, resulting in an increase in load or a decrease in reliability. Yes, it has been obtained in advance by experiments. If a negative determination is made here, it can be determined that the degree of oil dilution is sufficiently low, so the process returns to S101 and the processes of S101 and S102 are executed again. The processes of S101 and S102 are repeatedly executed until an affirmative determination is made in S102. If an affirmative determination is made in S102, the degree of oil dilution increases and it is determined that the above-described problem may occur, so the process proceeds to S103.

  In S103, it is determined whether or not the cam selected at this time is the first cam 1 having the high lift profile. If a negative determination is made here, the process returns to S101. On the other hand, if a positive determination is made, the process proceeds to S104.

  In S104, the selected cam is switched from the first cam 1 to the second cam 2 having a low lift profile. When the process of S104 is completed, this routine is temporarily ended.

  As described above, in this embodiment, when the degree of oil dilution exceeds the threshold value, first, the cam profile of the valve mechanism 10 is switched to the low lift profile, and the lift amount of the intake valve 6 is reduced. To reduce the combustion pressure in the cylinder. Thereby, the load concerning the mechanism of the output system such as the crankshaft 15 can be reduced. At the same time, the cam profile of the valve mechanism 10 is switched to the low lift profile, so that the load acting on the cam switching mechanism 10a itself such as the rocker arm 4 and the intake valve 6 is reduced. Accordingly, it is possible to suppress the disadvantage that the lubricating performance of the engine oil is reduced due to the oil dilution and the load is increased and the durability is lowered in the sliding portion.

  In the above description, the cam switching mechanism 10a corresponds to the cam profile switching mechanism and the output improvement mechanism in this embodiment. The viscosity sensor 19 constitutes an oil dilution detection means. The threshold value in S102 corresponds to a predetermined degree for the degree of dilution of the engine oil.

[Example 2]
Next, a second embodiment of the present invention will be described. In this embodiment, the valve timing depends on the degree of oil dilution. The normal valve timing is normally used from the high output timing at which high engine output is enabled by a variable valve mechanism (hereinafter referred to as “VVT”). An example of switching to output timing will be described. In addition, about the internal combustion engine and VVT in a present Example, since what is generally used is used, description by a figure is abbreviate | omitted.

  In FIG. 3, the flowchart about the mechanism change routine 2 at the time of oil dilution in a present Example is shown. This routine is a program stored in the ROM in the ECU, and is a routine executed by the ECU at predetermined intervals while the internal combustion engine is operating.

  Since the processing of S101 and S102 in this routine is the same as the processing in the oil dilution mechanism changing routine shown in the first embodiment, description thereof will be omitted. In this embodiment, when an affirmative determination is made in the process of S102, the process proceeds to S201.

  In S201, it is determined whether or not the valve timing set by the VVT at this time is a high output timing. Here, the high output timing indicates a valve timing that is selected when the engine output required by the driver is a high output of a certain level or more, and the range is determined in advance by experiments or the like. If a negative determination is made in S201, the process returns to the step before S101. On the other hand, if a positive determination is made, the process proceeds to S202.

  In S202, the valve timing is changed from the high output valve timing to the normal valve timing used in a general traveling state by VVT. When the process of S202 ends, this routine is temporarily ended.

  As described above, in this embodiment, when the degree of oil dilution is larger than the threshold value, the valve timing is changed from the high output valve timing to the normal valve timing by the VVT. Then, since the engine output decreases, the load on the output system mechanism such as the crankshaft can be reduced. Therefore, the lubrication performance of engine oil decreases due to oil dilution, and it is possible to suppress inconveniences such as an increase in operating resistance and a decrease in durability particularly in a sliding part of an output system mechanism such as a crankshaft with a large load. .

  In this embodiment, VVT corresponds to the output improvement mechanism. In this embodiment, an example in which VVT is applied to an intake valve has been described. However, the present invention is applied to an internal combustion engine in which output is improved by applying VVT to an exhaust valve (or an intake valve and an exhaust valve). It doesn't matter.

Example 3
Next, a third embodiment of the present invention will be described. In the present embodiment, an example in which the valve opening period and the lift amount are changed depending on the degree of oil dilution will be described.

  First, the schematic configuration of the oscillating variable valve mechanism 20 according to the present invention will be described with reference to FIG. In FIG. 4, the swing type variable valve mechanism 20 is provided for the intake valve 26. In the oscillating variable valve mechanism 20, the rotational motion of the cam shaft 23 is converted into the oscillating motion of the rocker arm 24 by the cam 22 provided on the cam shaft 23, and the intake valve 26 supported by the rocker arm 24 is vertically moved. Converted to lift movement. A part of the outer periphery of the cam 22 is formed such that the distance from the center of the cam shaft 23 gradually increases and gradually decreases after exceeding the top, thereby forming a cam nose 22a.

  In the swing type variable valve mechanism 20, the variable mechanism 30 is interposed between the cam 22 and the rocker arm 24. The variable mechanism 30 is a mechanism that can continuously change the interlocking state between the rotational movement of the cam 22 and the rocking movement of the rocker arm 24. In the oscillating variable valve mechanism 20 in the present embodiment, by controlling the variable mechanism 30, the operation amount and operation timing of the rocker arm 24 are changed, and the lift amount and valve opening period of the intake valve 26 are continuously set. It can be changed.

  The variable mechanism 30 includes a control shaft 32, a control plate 33, a control arm 34, a swing cam 35, and an intermediate roller 36. The control shaft 32 is disposed in parallel with the cam shaft 23. The rotation angle of the control shaft 32 is controlled by an actuator such as a motor (not shown).

The control plate 33 is integrally fixed to the control shaft 32. A part of the control plate 33 forms a protruding portion 33 a that protrudes in the radial direction of the control shaft 32. A control arm 34 is rotatably attached to the protrusion 33a. An intermediate roller 36 is provided at the tip of the control arm 34. The intermediate roller 36 is in contact with the cam 12 and rotates first.
A second intermediate roller 36b that rotates in direct contact with a slide surface 350 (described later) of the intermediate roller 36a and the swing cam 35 is provided independently.

  The swing cam 35 is rotatably attached to the control shaft 32. A slide surface 350 on which the second intermediate roller 36b rotates is formed on the swing cam 35 on the intermediate roller 36 side.

  A rocker arm contact surface 351 is formed on the opposite side of the swing cam 35 from the slide surface 350. Further, the rocker arm 24 is disposed so as to face the rocker arm contact surface 351. A rocker roller 24 a is rotatably attached to an intermediate portion of the rocker arm 24. A rear end portion of the intake valve 26 is attached to one end of the rocker arm 24, and the other end of the rocker arm 24 is rotatably supported by a hydraulic lash adjuster 38.

  Further, the swing cam 35 is biased in a counterclockwise direction in FIG. 4 by a biasing spring (not shown). Due to this urging force, the swing cam 35 abuts against the second intermediate roller 36 b, and further, the first intermediate roller 36 a coaxial with the second intermediate roller 36 b abuts against the cam 22.

  In this configuration, when the cam shaft 23 rotates, the cam nose 22a of the cam 22 contacts the first intermediate roller 36a. As a result, the intermediate roller 36 is periodically pushed down toward the swing cam 35. Then, the second intermediate roller 36b periodically pushes down the slide surface 350 of the swing cam 35, whereby the swing cam 35 swings. Further, the rocker arm contact surface 351 of the swing cam 35 periodically pushes down the rocker roller 24 a of the rocker arm 24.

  Therefore, when the cam shaft 23 rotates, the swing cam 35 swings around the control shaft 32, so that the contact position of the rocker roller 24a on the rocker arm contact surface 351 changes. Then, the rocker arm 24 is pushed down according to the distance of the rocker arm contact surface 351 from the center of the control shaft 32 and swings counterclockwise around the support point by the hydraulic lash adjuster 38. As a result, the intake valve 26 is periodically pushed down to perform the valve opening operation.

  Next, the changing operation of the lift amount and the valve opening period of the intake valve 26 in the swing type variable valve mechanism 20 will be described. When changing the lift amount and valve opening period of the intake valve 26, the control shaft 32 is driven to rotate counterclockwise in FIG. Then, the protruding portion 33a moves around the control shaft 32 in an arc shape counterclockwise. At this time, since the intermediate roller 36 is held at a constant distance from the protrusion 33a by the control arm 34, the second intermediate roller 36b moves in a direction away from the control shaft 32 along the slide surface 350, and at the same time, The first intermediate roller 36a moves along the drive cam 12a to the upstream side in the rotational direction.

  As the second intermediate roller 36b moves away from the control shaft 32, the distance from the center of the control shaft 32 to the contact position on the slide surface 350 of the second intermediate roller 36b becomes longer, and the swing cam 35 The swing angle decreases. As a result, the lift amount of the intake valve 26 is reduced and the opening timing of the intake valve 26 is delayed.

  On the other hand, when the second intermediate roller 36b moves away from the control shaft 32, the cam nose 22a of the cam 22 acts on the first intermediate roller 36a earlier when the cam shaft 23 rotates. As a result, the opening timing of the intake valve 26 is advanced.

That is, when the intermediate roller 36 moves away from the control shaft 32, the lift amount of the intake valve 26 decreases, and as a result, the opening timing of the intake valve 26 changes to the retard side, and the cam 22 As the timing at which the cam nose 22a acts on the intermediate roller 36 becomes earlier, a phenomenon occurs in which the opening timing of the intake valve 26 changes to the advance side.

  That is, by appropriately determining the shapes of the slide surface 350 and the rocker arm contact surface 351, the swing angle of the swing cam 35 when the intermediate roller 36 moves on the slide surface 350 toward the tip side of the swing cam 35. And change of swing timing can be set. Then, by changing the rotation angle of the control shaft 32, the lift amount and the valve opening period of the intake valve 26 can be controlled based on the setting.

  FIG. 5 shows an example of a change pattern of the lift amount and valve opening period of the intake valve 26 by the swing type variable valve mechanism 20. A plurality of curves in the drawing are curves showing temporal changes in the lift amount of the intake valve 26 when the control shaft 32 is changed variously. As shown in FIG. 5, by appropriately determining the shapes of the slide surface 350 and the rocker arm contact surface 351, for example, the valve opening period (and the lift amount) is changed while keeping the valve opening timing of the intake valve 26 constant. It is possible. In this embodiment, in FIG. 5, for example, a valve opening period corresponding to a range of L1 to L3 (including L3) is defined as a high power valve opening period, and a valve opening period corresponding to L3 to L5 (not including L3). Is defined as the normal valve opening period.

  In FIG. 6, the flowchart about the mechanism change routine 3 at the time of oil dilution in a present Example is shown. In this routine, S101 and S102 are equivalent to the routine 2 and will not be described. When it is determined in S102 of this routine that the oil dilution degree is larger than the threshold value, the process proceeds to S301.

  In S301, it is determined whether or not the high output valve opening period is being used. If it is determined in S301 that the high-power valve opening period is not used, the process returns to S101. On the other hand, if it is determined that the high-power valve opening period is being used, the process proceeds to S302.

  In S302, the valve opening period is changed to the normal valve opening period by changing the rotation angle of the control shaft 32. When the process of S302 ends, this routine is temporarily ended.

  According to the present embodiment, when it is determined that the degree of oil dilution is greater than the predetermined degree, the control valve 32 is rotated to shorten the valve opening period of the intake valve 26 and reduce the lift amount. The engine output can be reduced. If it does so, the load concerning the mechanism of output systems, such as a crankshaft, can be reduced. At this time, since the load for opening the intake valve 26 against the valve spring is reduced, the swinging variable valve mechanism 20 including the rocker arm 24, the intake valve 26, the variable mechanism 30, the cam shaft 23, and the like. The load acting on itself is also reduced. Therefore, the lubrication performance of the engine oil is reduced by the oil dilution, and it is possible to suppress inconveniences that increase the load and decrease the durability at each sliding portion.

  In the above description, the oscillating variable valve mechanism 20 corresponds to a valve opening period changing mechanism and an output improving mechanism. The rocker arm 24 constitutes a transmission mechanism. Further, in this embodiment, the example in which the swing type variable valve mechanism is applied to the intake valve has been described, but the output is improved by applying the mechanism to the exhaust valve (or the intake valve and the exhaust valve). The present invention may be applied to an internal combustion engine.

Example 4
Next, a fourth embodiment of the present invention will be described. In this embodiment, in an internal combustion engine equipped with a variable compression ratio mechanism that can change the compression ratio by changing the volume of the combustion chamber, when the degree of oil dilution is greater than a predetermined degree, the compression ratio is An example of changing from a high compression ratio to a low compression ratio will be described.

  FIG. 7 is a diagram illustrating a schematic configuration of an internal combustion engine (hereinafter simply referred to as “internal combustion engine”) 50 including the variable compression ratio mechanism 40 in the present embodiment. The internal combustion engine 50 is a four-cylinder internal combustion engine having four cylinders 53 in a direction perpendicular to the paper surface. The piston 52 connected to the crankshaft 55 of the internal combustion engine 50 via the connecting rod 57 performs a reciprocating motion in the cylinder 53.

  Here, in the internal combustion engine 50, the compression ratio of the internal combustion engine 50 is changed by moving the cylinder block 51 relative to the crankcase 56 in the axial direction of the cylinder 53 by the variable compression ratio mechanism 40. That is, the variable compression ratio mechanism 40 is constituted by the cylinder block 51, the cylinder head 54, and the piston 52 by moving the cylinder head 54 together with the cylinder block 51 relative to the crankcase 56 in the axial direction of the cylinder 53. The volume of the combustion chamber is changed, and as a result, the compression ratio of the internal combustion engine 50 is variably controlled. For example, when the cylinder block 51 is relatively moved away from the crankcase 56, the combustion chamber volume increases and the compression ratio decreases.

  The variable compression ratio mechanism 40 is the same as the cam portion 40a, a cam portion 40b having a circular cam profile fixed to the shaft portion 40a while being eccentric with respect to the central axis of the shaft portion 40a, and the cam portion 40b. A movable bearing portion 40c having an outer shape and rotatable with respect to the shaft portion 40a and attached in an eccentric manner like the cam portion 40b, a worm wheel 40d provided concentrically with the shaft portion 40a, and a worm wheel 40d And a motor 40f that rotationally drives the worm 40e. The cam portion 40 b is installed in a storage hole provided in the cylinder block 51, the movable bearing portion 40 c is installed in a storage hole provided in the crankcase 56, and the motor 40 f is fixed to the cylinder block 51. And moves integrally with the cylinder block 51. Here, the driving force from the motor 40f is transmitted to the shaft portion 40a via the worm 40e and the worm wheel 40d. Then, the cam block 40 b and the movable bearing portion 40 c in an eccentric state are driven, so that the cylinder block 51 is moved relative to the crankcase 56 in the axial direction of the cylinder 53.

  The internal combustion engine 50 is also provided with an ECU 58. By the command of the ECU 58, the compression ratio of the internal combustion engine 50 is changed according to the operating state. Here, when the compression ratio is set to a relatively high compression ratio, the compression ratio is set to a relatively low compression ratio because the combustion efficiency is good and the volume of the combustion chamber is reduced. The combustion pressure tends to be higher than the case. Then, when the compression ratio is set to a relatively high compression ratio, the load related to the output system mechanism such as the crankshaft 55 tends to increase. Further, the higher the compression ratio, the larger the load that acts in the direction of separating the crankcase 56 and the cylinder block 51 due to the combustion pressure, so the load acting on the variable compression ratio mechanism 40 also increases.

  In FIG. 8, the flowchart about the mechanism change routine 4 at the time of oil dilution in a present Example is shown. In this routine, S101 and S102 are equivalent to the routine 3 and will not be described. If it is determined in S102 of this routine that the oil dilution degree is greater than the threshold value, the process proceeds to S401.

In S401, it is determined whether or not the compression ratio is set to a high compression ratio. In S401, when it is determined that the compression ratio is not set to the high compression ratio, the process returns to the step before S101. On the other hand, if it is determined that the compression ratio is set to a high compression ratio, the process proceeds to S402. Here, the high compression ratio indicates a compression ratio higher than a predetermined threshold compression ratio. The predetermined threshold compression ratio is a compression ratio value set in advance in relation to the threshold value in S102. When the compression ratio is higher than this (when the compression ratio is set to a high compression ratio), oil dilution is performed. In a state where the degree is larger than the threshold value, a compression ratio at a limit that may cause problems such as excessive load during operation or reduced durability in the output system mechanism such as the crankshaft 55 or the variable compression ratio mechanism 40. It is.

  In S402, the motor 40f is operated based on a command from the ECU 58, and the compression ratio is changed to a low compression ratio. When the process of S402 ends, this routine is temporarily ended.

  According to the present embodiment, when it is determined that the degree of oil dilution is greater than a predetermined degree, the combustion pressure generated in the cylinder 53 can be reduced by a simple control of changing the compression ratio to a low compression ratio. it can. If it does so, the load concerning the mechanism of output systems, such as crankshaft 55, can be reduced. At the same time, the load acting on each member of the variable compression ratio mechanism 40 is also reduced. Therefore, the lubrication performance of the engine oil is reduced by the oil dilution, and it is possible to suppress inconveniences that increase the load and decrease the durability at each sliding portion.

Example 5
Next, a fifth embodiment of the present invention will be described. In the present embodiment, in an internal combustion engine having a variable nozzle mechanism capable of changing the nozzle vane opening degree in the turbocharger turbine, when the degree of oil dilution is greater than a predetermined degree, the variable nozzle mechanism An example of changing the opening will be described.

  In this embodiment, the supercharger of the internal combustion engine is provided with a variable nozzle mechanism 60 that can control the supercharging pressure by controlling the exhaust speed flowing into the turbine with the nozzle vane opening being variable. It is assumed. FIG. 9 shows a state when the variable nozzle mechanism 60 in the present embodiment is opened, and FIG. 10 shows a state when the device 60 is closed.

  As shown in FIG. 9, the variable nozzle mechanism 60 in the present embodiment has a plurality of nozzle vanes 62 arranged at the inflow portion of the exhaust gas to the turbine wheel 61. In addition, a nozzle plate 64 that holds the nozzle vane 62 through a shaft 63 so as to be swingable, a unison ring 66 that rotates the shaft 63 through an arm 65 fixed to the end of each shaft 63, and the like.

  Furthermore, the variable nozzle mechanism 60 includes a drive motor (not shown), a motor rod 68 pushed and pulled by the operation of the drive motor, and a drive arm 67 that rotates by pushing and pulling the motor rod 68 to rotate the unison ring 66. Yes.

  FIG. 9A and FIG. 10A show the surface of the variable nozzle mechanism 60 opposite to the nozzle vane 62. On the other hand, FIG. 9B and FIG. 10B show the surface of the variable nozzle mechanism 60 on the nozzle vane 62 side.

  In FIG. 9, when the motor rod 68 is pulled by driving the drive motor, the unison ring 66 rotates clockwise in FIG. Then, the arm 65 engaged with the unison ring 66 is swung around the shaft 63, and the opening degree of the nozzle vane 62 is changed to the open side by the rotation of the shaft 63.

  On the contrary, in FIG. 10, when the motor rod 68 is pushed by driving the drive motor, the unison ring 66 rotates counterclockwise in FIG. Then, the arm 65 engaged with the unison ring 66 is swung around the shaft 63, and the opening degree of the nozzle vane 62 is changed to the closed side by the rotation of the shaft 63.

In FIG. 11, the flowchart about the mechanism change routine 5 at the time of oil dilution in a present Example is shown. In this routine, S101 and S102 are equivalent to the routine 4 and will not be described. When it is determined in S102 of this routine that the oil dilution degree is larger than the threshold value, the process proceeds to S501.

  In S501, it is determined whether or not the opening degree of the nozzle vane 62 is closed. In S501, when it is determined that the opening degree of the nozzle vane 62 is not on the closed side, the process returns to S101. On the other hand, when it is determined that the opening degree of the nozzle vane 62 is on the closed side, the process proceeds to S502. Here, the closed side of the nozzle vane opening means that the opening is set closer to the closing side than a predetermined threshold opening. The predetermined threshold opening is a value of the opening of the nozzle vane 62 set in advance in relation to the threshold in S102, and when the opening of the nozzle vane 62 is closer to this, the degree of oil dilution is larger than the threshold. In this state, the compression ratio is a limit that may cause a problem that an output system mechanism such as a crankshaft or the load applied to the nozzle vane 62 itself becomes excessive or the durability is lowered.

  In S502, a drive motor (not shown) is operated to change the opening degree of the nozzle vane 62 to the open side. When the processing of S502 ends, this routine is once ended.

  According to this embodiment, when it is determined that the degree of oil dilution is greater than the predetermined degree, the supercharging pressure is reduced by a simple control of changing the opening of the nozzle vane of the supercharger to the open side. The engine output can be reduced. If it does so, the load concerning the mechanism of output systems, such as a crankshaft, can be reduced. At the same time, since the turbine inlet pressure of the supercharger is also reduced, the load acting on the variable nozzle mechanism 60 including the nozzle vane 62 is also reduced. Therefore, the lubrication performance of the engine oil is reduced by the oil dilution, and it is possible to suppress inconveniences that increase the load and decrease the durability at each sliding portion. In this embodiment, the variable nozzle mechanism 60 corresponds to an output improvement mechanism.

Example 6
Next, a sixth embodiment of the present invention will be described. In this embodiment, the opening degree of the intake control valve in the internal combustion engine is temporarily closed in synchronism with the intake valve, and the intake control valve is opened while the intake valve is opened, thereby producing a supercharging effect. (Hereinafter referred to as “impulse supercharging”) is an example of an internal combustion engine provided with an impulse charge mechanism for improving the output of the internal combustion engine. That is, in this embodiment, when the oil dilution degree is larger than the predetermined degree, the impulse supercharging by the impulse charge mechanism is stopped.

  FIG. 12 shows a schematic configuration of the internal combustion engine 90 in the present embodiment. The intake passage 71 in the internal combustion engine 90 is provided with an air flow meter 72, an intake throttle valve 73, and an intake control valve 74 in order from the upstream side. These constitute the impulse charge mechanism 70.

  The internal combustion engine 90 is also provided with an EGR device 80 for performing exhaust gas recirculation (EGR). The EGR device 80 includes an EGR passage 81 that connects the intake passage 71 and the exhaust passage 92, and an EGR valve 82 and an EGR cooler 83 that are provided in the EGR passage 81. The downstream end of the EGR passage 81 is connected to the intake passage 71 between the intake throttle valve 73 and the intake control valve 74.

  The intake control valve 74 is provided with an electric actuator such as a rotary solenoid (not shown). The intake control valve 74 can close the intake passage 71. In particular, in the present embodiment, unlike the intake throttle valve 73, the intake passage 71 is completely closed when the valve is fully closed, and the passage of intake air is completely blocked. It has a highly sealed structure. In contrast, the intake throttle valve 73 allows the intake air to pass only by restricting the intake passage 71 to the maximum when the intake throttle valve 73 is fully closed.

Further, the electric actuator of the intake control valve 74 can operate at a higher speed than the electric actuator of the intake throttle valve 73 and has high responsiveness, and can be opened and closed within 1 msec, for example. Thus, the intake control valve 74 can be opened and closed in synchronization with the opening and closing of the intake valve 94.

  The opening degree of the intake control valve 74 is controlled from fully open to fully closed in accordance with an opening signal output from the ECU 98 to the electric actuator. Further, the intake control valve 74 is provided for each cylinder 93, and the intake air introduced for each cylinder 93 can be individually controlled.

  The intake control valve 74 in the present embodiment is used for performing so-called impulse supercharging during normal operation. In this impulse supercharging, the intake control valve 74 is controlled so as to be opened later than the intake valve 94 is opened, for example, at a later stage of the valve opening period of the intake valve 94. Then, a negative pressure is formed in the intake passage 71 between the intake control valve 74 and the intake valve 94 between the opening start timing of the intake valve 94 and the opening start timing of the intake control valve 74. By opening the control valve 74 instantaneously, the intake air in the intake passage 71 located on the upstream side of the intake control valve 74 flows into the cylinder 93 at once, and a large amount of intake air flows into the cylinder 93 due to a kind of inertia supercharging effect. Can be filled. Thereby, the engine output of the internal combustion engine 90 can be improved.

  In the present embodiment, in the internal combustion engine 90 having such an impulse charge mechanism 70, when the oil dilution degree becomes larger than a predetermined degree, the operation of the intake control valve 74 is stopped to stop the impulse supercharging. did.

  In FIG. 13, the flowchart about the mechanism change routine 6 at the time of oil dilution in a present Example is shown. In this routine, S101 and S102 are equivalent to the routine 5 and will not be described. When it is determined in S102 of this routine that the oil dilution degree is larger than the threshold value, the process proceeds to S601.

  In S601, it is determined whether or not impulse supercharging control is being executed. If it is determined in S601 that the impulse supercharging control is not being executed, the process returns to S101. On the other hand, when it is determined that the impulse charge control is being executed, the process proceeds to S602.

  In S602, the intake control valve 74 is stopped in the open state, and the impulse charge is stopped. When the processing of S602 ends, this routine is once ended.

  According to the present embodiment, when it is determined that the degree of oil dilution is greater than the predetermined degree, the boost pressure is reduced by a simple control of stopping the operation command to the intake control valve 74 and stopping the impulse charge. The engine output can be reduced by reducing the engine output. If it does so, the load concerning the mechanism of output systems, such as a crankshaft, can be reduced. At the same time, the negative pressure acting on the intake control valve 74 itself can be reduced by stopping the impulse supercharging. Therefore, the lubrication performance of the engine oil is reduced by the oil dilution, and it is possible to suppress inconveniences that increase the load and decrease the durability at each sliding portion. In this embodiment, the impulse charge mechanism 70 corresponds to an output improvement mechanism.

  In the above six embodiments, when the degree of oil dilution in the internal combustion engine is larger than a predetermined degree, the operation of the output improvement mechanism that mechanically improves the engine output is stopped. In addition, it may be used in combination with control for reducing the fuel injection amount and limiting the engine speed of the internal combustion engine to a predetermined low speed range by software-switching the map storing the fuel injection amount data. .

Here, the predetermined low rotational speed range is an engine rotational speed range on the low rotational speed side defined in advance by experiments or the like, and the crankshaft is limited by limiting the engine rotational speed within this low rotational speed range. It is an engine speed range that is considered to reduce the load acting on the output system mechanism.

  According to this, by reducing the engine speed of the internal combustion engine, it is possible to more reliably reduce the load acting on the output system mechanism such as the crankshaft, and inconvenience such as seizure at each sliding portion. Generation can be suppressed more reliably.

  In the processing of S102 in the oil dilution mechanism changing routine to the oil dilution mechanism changing routine 6 in the above six embodiments, it is determined whether or not the oil dilution degree is larger than a threshold value. Independently optimized values experimentally in each embodiment may be used.

DESCRIPTION OF SYMBOLS 1 ... 1st cam 2 ... 2nd cam 3 ... Cam shaft 4 ... Rocker arm 6 ... Intake valve 10 ... Valve operating mechanism 10a ... Cam switching mechanism 11 ... OCV
15 ... Crankshaft 18 ... ECU
DESCRIPTION OF SYMBOLS 19 ... Viscosity sensor 20 ... Swing type variable valve mechanism 24 ... Rocker arm 30 ... Variable mechanism 35 ... Swing cam 36 ... Intermediate roller 40 ... Variable compression ratio mechanism 50 ... Internal combustion engine 60 ... Variable nozzle mechanism 62 ... Nozzle vane 68 ... Motor rod 70 ... Impulse charge mechanism 73 ... Intake throttle valve 74 ... Intake control valve

Claims (5)

An output improving mechanism for improving the output of the internal combustion engine based on mechanical operation;
Oil dilution detection means for detecting the degree of dilution of the engine oil in the internal combustion engine with fuel;
With
The output enhancement mechanism is
A variable valve mechanism that is capable of changing a rotation phase of a cam of a valve mechanism in the internal combustion engine, and improving an output of the internal combustion engine by changing a valve timing by changing the rotation phase of the cam.
When the degree of dilution of the engine oil detected by the oil dilution detection means is greater than a predetermined degree,
A control system for an internal combustion engine, wherein an improvement in output of the internal combustion engine by the variable valve mechanism is stopped by changing a valve timing in the variable valve mechanism from a high output valve timing to a normal valve timing. The output enhancement mechanism is
2. The control system for an internal combustion engine according to claim 1, further comprising a variable compression ratio mechanism for improving an output of the internal combustion engine by increasing a compression ratio by reducing a volume of a combustion chamber in the internal combustion engine. The output enhancement mechanism is
The variable nozzle mechanism for improving the output of the internal combustion engine by changing an opening degree of a nozzle vane provided in a turbine of a supercharger in the internal combustion engine to a closed side. Control system for internal combustion engine. The output enhancement mechanism is
By temporarily closing the intake control valve provided in the intake passage in the internal combustion engine and performing the impulse supercharging to open the intake control valve while the intake valve is open, the output of the internal combustion engine is reduced. The control system for an internal combustion engine according to claim 3, further comprising an impulse charge mechanism that improves the control system. When the degree of dilution of the engine oil detected by the oil dilution detection means is greater than a predetermined degree,
The internal combustion engine control system according to any one of claims 1 to 4, wherein the engine speed of the internal combustion engine is limited to a predetermined low speed range.

Images