JP6186856B2 - Control device and control method for internal combustion engine - Google Patents

Description

  The present invention relates to a control device and control method for an internal combustion engine having a variable compression ratio mechanism, and more particularly to a technique for suppressing poor lubrication due to oil deterioration.

  Various types of variable compression ratio mechanisms for changing the mechanical compression ratio of an internal combustion engine have been known. For example, the applicants have proposed a number of variable compression ratio mechanisms in which the piston top dead center position is displaced up and down by changing the link geometry of a multi-link piston crank mechanism. A variable compression ratio mechanism is also known in which the mechanical compression ratio is similarly changed by displacing the cylinder position up and down with respect to the center position of the crankshaft.

  In such a variable compression ratio mechanism, it is basically desirable that the compression ratio be as high as possible without causing abnormal combustion such as knocking. Therefore, as a general tendency of the target compression ratio, the load is The lower the value, the higher the compression ratio.

  By the way, the oil that lubricates each part of the internal combustion engine is collected in the crankcase at the lower part of the cylinder block and is sent again from here to the oil gallery or the like by the oil pump, but the blow-by leaked from the combustion chamber in the crankcase. Since it contacts with gas, there exists a problem that oil deteriorates with NOx contained in blow-by gas. If the oil deterioration is left unattended, poor lubrication of each part occurs due to a decrease in viscosity. Patent Document 1 discloses that such oil deterioration is optically detected and notified to the driver when the oil replacement time is approaching.

JP 2010-145107 A

  The above-mentioned Patent Document 1 does not describe the compression ratio of the internal combustion engine, and merely informs the driver when the oil replacement time is approaching. An object of the present invention is to suppress the further progress of the oil deterioration as much as possible when the oil change time approaches by utilizing the change of the mechanical compression ratio by the variable compression ratio mechanism.

The present invention is a control apparatus for an internal combustion engine having a variable compression ratio mechanism for changing the mechanical compression ratio, means for determining the deterioration of the oil deteriorated by the blow-by gas has reached a predetermined degree of deterioration, the driver Warning means for notifying the user that the oil needs to be changed, and when the oil deterioration reaches a predetermined deterioration level, the compression ratio by the variable compression ratio mechanism is lowered and the warning means is activated. make, it is characterized in that.

When the mechanical compression ratio of the internal combustion engine is high, the combustion temperature becomes high, and the amount of NOx generated and thus the NOx contained in the blow-by gas also increases. It is desirable that the compression ratio of the variable compression ratio mechanism be as high as possible within a range that does not cause abnormal combustion such as knocking from the viewpoint of improving thermal efficiency, but in the present invention, when the deterioration of the oil reaches a predetermined degree of deterioration. a is set low mechanical compression ratio, and Ru is performed notified to the driver. Thereby, NOx contained in blow-by gas decreases, and the progress of subsequent oil deterioration is suppressed. Therefore, the risk of poor lubrication due to oil deterioration between the notification to the driver and the oil change is reduced.

  According to the present invention, when the deterioration of the oil reaches a predetermined deterioration level, the mechanical compression ratio is lowered, so that the progress of the subsequent oil deterioration can be suppressed, and poor lubrication due to the oil deterioration occurs. Risk can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Structure explanatory drawing which shows the system structure of the control apparatus which concerns on one Example of this invention. The flowchart which shows the flow of control in this Example.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the system configuration of an automotive internal combustion engine 1 to which the present invention is applied. The internal combustion engine 1 is a four-stroke cycle direct injection type spark ignition internal combustion engine having a variable compression ratio mechanism 2 using, for example, a multi-link type piston crank mechanism. The intake valve 4 and a pair of exhaust valves 5 are disposed, and a spark plug 6 is disposed in a central portion surrounded by the intake valves 4 and the exhaust valves 5.

  A fuel injection valve 8 that directly injects fuel into the combustion chamber 3 is disposed below the intake port 7 that is opened and closed by the intake valve 4. The fuel injection valve 8 is an electromagnetic or piezoelectric injection valve that opens when a drive pulse signal is applied, and injects an amount of fuel substantially proportional to the pulse width of the drive pulse signal. .

  An electronically controlled throttle valve 19 whose opening degree is controlled by a control signal from the engine controller 9 is interposed on the upstream side of the collector portion 18a of the intake passage 18 connected to the intake port 7, and further upstream thereof. On the side, an air flow meter 10 for detecting the intake air amount is disposed.

  In addition, a catalyst device 13 made of a three-way catalyst is interposed in the exhaust passage 12 connected to the exhaust port 11, and an air-fuel ratio sensor 14 for detecting the air-fuel ratio is disposed upstream thereof.

  In addition to the air flow meter 10 and the air-fuel ratio sensor 14, the engine controller 9 includes a crank angle sensor 15 for detecting the engine speed, a water temperature sensor 16 for detecting the coolant temperature, and an accelerator pedal operated by the driver. Detection signals of sensors such as an accelerator opening sensor 17 that detects the amount of depression of the vehicle are input. Based on these detection signals, the engine controller 9 optimally controls the fuel injection amount and injection timing by the fuel injection valve 8, the ignition timing by the spark plug 6, the opening of the throttle valve 19, and the like.

  The internal combustion engine 1 also includes an oil deterioration sensor 41 for measuring deterioration of oil that lubricates each part. Although the lubricating mechanism of the internal combustion engine 1 that uses this oil is not particularly shown, the oil is temporarily stored in the bottom of the crankcase (a so-called oil pan portion) below the cylinder block 29, and an oil pump (not shown) The sucked-up oil has a general configuration in which it is pumped to each part through an oil gallery. As a method for detecting the deterioration of the oil of the internal combustion engine 1, in addition to the optical method as in Patent Document 1, an electrical method for detecting the capacitance or potential difference of the oil, a decrease in viscosity, a pressure change, etc. There are various known methods such as a method for detecting from the oil, a method for chemically detecting the change in the chemical characteristics of the oil, and the oil deterioration sensor 41 of the embodiment is an appropriate sensor corresponding to these detection methods. (Including those composed of a plurality of probes) are used, and depending on the type, an oil pan portion in which oil is stored and an oil passage through which oil passes are disposed at appropriate positions. The detection signal of the oil deterioration sensor 41 is input to the engine controller 9, and it is determined whether or not a predetermined degree of deterioration has been reached, as will be described later. For example, a warning lamp 42 is provided as warning means for notifying the driver that oil replacement is necessary when a predetermined degree of deterioration is reached. Note that an acoustic warning means such as a voice or a warning sound may be used instead of the visual notification such as the warning lamp 42.

  On the other hand, the variable compression ratio mechanism 2 uses a known multi-link type piston crank mechanism described in Japanese Patent Application Laid-Open No. 2004-116434 and is rotatably supported by the crank pin 21a of the crankshaft 21. A lower link 22, an upper link 25 that connects the upper pin 23 at one end of the lower link 22 and the piston pin 24 a of the piston 24, and a control having one end connected to a control pin 26 at the other end of the lower link 22. The link 27 and a control shaft 28 that pivotally supports the other end of the control link 27 are mainly configured. The crankshaft 21 and the control shaft 28 are rotatably supported in a crankcase below the cylinder block 29 via a bearing structure (not shown). The control shaft 28 has an eccentric shaft portion 28a whose position changes with the rotation of the control shaft 28. Specifically, the end portion of the control link 27 is rotatably fitted to the eccentric shaft portion 28a. Match. In the variable compression ratio mechanism 2 described above, the top dead center position of the piston 24 is displaced up and down with the rotation of the control shaft 28, so that the mechanical compression ratio changes.

  As a drive mechanism for variably controlling the compression ratio of the variable compression ratio mechanism 2, an electric motor 31 having a rotation center axis parallel to the crankshaft 21 is disposed below the cylinder block 29. A reduction gear 32 is connected so as to be arranged in series in the direction. As the speed reducer 32, for example, a wave gear mechanism having a large speed reduction ratio is used, and the speed reducer output shaft 32 a is positioned coaxially with the output shaft (not shown) of the electric motor 31. Accordingly, the speed reducer output shaft 32a and the control shaft 28 are positioned in parallel with each other, and the first arm 33 and the control shaft 28 fixed to the speed reducer output shaft 32a are connected to each other so that both of them rotate in conjunction with each other. The fixed second arm 34 is connected to each other by an intermediate link 35.

  That is, when the electric motor 31 rotates, the angle of the speed reducer output shaft 32a changes in a form greatly decelerated by the speed reducer 32. The rotation of the speed reducer output shaft 32a is transmitted from the first arm 33 to the second arm 34 via the intermediate link 35, and the control shaft 28 rotates. Thereby, as mentioned above, the mechanical compression ratio of the internal combustion engine 1 changes. In the illustrated example, the first arm 33 and the second arm 34 extend in the same direction. Therefore, for example, when the speed reducer output shaft 32a rotates in the clockwise direction, the control shaft 28 also rotates in the clockwise direction. Although it is related, the link mechanism can also be configured to rotate in the opposite direction.

  The target compression ratio of the variable compression ratio mechanism 2 is set in the engine controller 9 based on engine operating conditions (for example, required load and engine speed), and the electric motor 31 is driven so as to realize this target compression ratio. Be controlled.

  FIG. 2 is a flowchart showing the flow of compression ratio control that is repeatedly executed at predetermined time intervals during operation of the internal combustion engine 1 in the engine controller 9. In step 1, the intake air amount Qa of the internal combustion engine 1 (corresponding to the load of the internal combustion engine 1), the engine rotational speed Ne, and the oil deterioration degree Or are read. The oil deterioration degree Or is a parameter indicating the degree of oil deterioration and is calculated based on the detection signal of the oil deterioration sensor 41 using the above-described known method by another routine (not shown).

  In step 2, the basic target compression ratio ε0 is obtained based on the intake air amount Qa and the engine speed Ne with reference to a predetermined compression ratio map. This basic target compression ratio ε0 is basically determined so as to be as high as possible within a range in which abnormal combustion such as knocking does not occur, and has a tendency to become a high compression ratio on the low load side. ing.

  Next, in step 3, it is determined whether the oil deterioration degree Or is less than a predetermined deterioration degree, that is, a predetermined oil deterioration determination threshold value Orth. If the oil deterioration degree Or is less than the oil deterioration determination threshold Orth, the process proceeds to step 4 and the basic target compression ratio ε0 is used as it is as the final target compression ratio tε. The oil deterioration determination threshold value Orth is set so as to correspond to the degree of deterioration that requires oil replacement. That is, if the operation of the internal combustion engine 1 is continued as it is, seizure of sliding parts and parts due to poor lubrication. This corresponds to a deteriorated state that may cause damage.

  If the oil deterioration degree Or is equal to or greater than the oil deterioration determination threshold Orth in step 3, the process proceeds to step 5 and the warning lamp 42 is turned on to notify the driver that the oil replacement time has come and to prompt the oil replacement. . In step 6, the compression ratio decrease correction amount εh is obtained based on the oil deterioration degree Or at that time. The compression ratio decrease correction amount εh becomes a larger value as the oil deterioration degree Or is larger (in a state where deterioration is progressing). That is, if the operation is continued even after the oil deterioration degree Or becomes equal to the oil deterioration determination threshold value Orth and the warning lamp 42 is turned on, the compression ratio reduction correction amount εh obtained in step 6 gradually increases.

  In step 7, the temporary target compression ratio ε1 is obtained as “ε1 = ε0−εh”. That is, the temporary target compression ratio ε1 corresponds to the corrected compression ratio when the basic target compression ratio ε0 is corrected to the low compression ratio side with the compression ratio decrease correction amount εh corresponding to the oil deterioration degree Or. In step 8, it is determined whether or not the temporary target compression ratio ε1 is larger than the minimum compression ratio εmin. The minimum compression ratio εmin is the lowest compression ratio that can be controlled by the variable compression ratio mechanism 2.

  If the temporary target compression ratio ε1 is larger than the minimum compression ratio εmin, the process proceeds to step 9 to set the temporary target compression ratio ε1 as the final target compression ratio tε. If the temporary target compression ratio ε1 is equal to or less than the minimum compression ratio εmin, the minimum compression ratio εmin is used as the final target compression ratio tε.

  As described above, in the above embodiment, when the oil has deteriorated to the extent that the oil needs to be changed, the driver is notified by turning on the warning lamp 42, and at the same time, the target compression ratio tε is forcibly reduced. As a result, although the thermal efficiency is reduced and a slight deterioration in fuel consumption is caused, the generation of NOx in the combustion chamber 3 and the concentration of NOx contained in the blow-by gas in the crankcase are suppressed by the reduction in the combustion temperature. Therefore, the progress of the subsequent oil deterioration is suppressed, and the risk of poor lubrication due to the oil deterioration before the actual oil change is reduced. In addition, since the combustion pressure peak decreases due to a decrease in the compression ratio, for example, in a lubricating portion where a combustion load acts such as a bearing portion of the crankshaft 21 or a piston pin 24a, it is more advantageous in avoiding seizure due to poor lubrication. It becomes.

  Here, in the above embodiment, since the compression ratio decrease correction amount εh is set according to the oil deterioration degree Or, a relatively small compression ratio decrease occurs immediately after the warning lamp 42 is lit, and thereafter, a long time operation is performed. If it continues, it will become a form fixed to minimum compression ratio (epsilon) min. Therefore, an excessive reduction in the compression ratio at a stage where there is a margin before the occurrence of poor lubrication is avoided.

  As another embodiment of the present invention, the target compression ratio tε may be fixed to the minimum compression ratio εmin when the oil deterioration degree Or becomes equal to or greater than the oil deterioration determination threshold Orth. In this way, the progress of oil deterioration is suppressed to the maximum.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, A various change is possible. For example, in the above embodiment, the variable compression ratio mechanism 2 that changes the compression ratio by moving the top dead center position of the piston 24 up and down is used, but the variable compression ratio of the type that moves the cylinder side up and down is used. The present invention can be similarly applied to the mechanism.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Variable compression ratio mechanism 8 ... Fuel injection valve 9 ... Engine controller 19 ... Throttle valve 41 ... Oil deterioration sensor 42 ... Warning light

Claims (5)

A control device for an internal combustion engine including a variable compression ratio mechanism for changing a mechanical compression ratio,
Means for determining that the deterioration of the oil deteriorated by blow-by gas has reached a predetermined deterioration level, and warning means for notifying the driver that oil replacement is necessary ,
A control apparatus for an internal combustion engine, wherein when the deterioration of oil reaches a predetermined deterioration level, the compression ratio by the variable compression ratio mechanism is lowered and the warning means is operated .   2. The control apparatus for an internal combustion engine according to claim 1, wherein the predetermined degree of deterioration is set to a degree of deterioration that requires oil replacement. 3. The control device for an internal combustion engine according to claim 1, wherein the compression ratio is set to a minimum compression ratio of the variable compression ratio mechanism when the deterioration of the oil reaches a predetermined degree of deterioration. When the oil deterioration reaches a predetermined deterioration level, the basic target compression ratio set according to the operating condition of the internal combustion engine is corrected to the low compression ratio side with a correction amount according to the degree of deterioration. performed, control apparatus for an internal combustion engine according to claim 1 or 2, characterized in. In an internal combustion engine having a variable compression ratio mechanism for changing a mechanical compression ratio,
Determine whether the oil deterioration due to blow-by gas has reached a predetermined degree of deterioration,
A control method for an internal combustion engine, characterized by lowering the compression ratio by the variable compression ratio mechanism and notifying the driver that oil replacement is required when the deterioration of oil reaches a predetermined degree of deterioration. .

Images