JP5038638B2 - Control device and control method for internal combustion engine - Google Patents

Description

  The present invention relates to a control technique for an internal combustion engine including a variable compression ratio mechanism capable of changing an engine compression ratio.

Patent Document 1 includes a variable compression ratio mechanism that can change the compression ratio of an internal combustion engine, and by setting the low load side to a high compression ratio and the high load side to a low compression ratio, knocking particularly on the high load side is performed. A technique for improving the fuel consumption rate by increasing the compression ratio on the low load side while preventing the occurrence is disclosed.
JP 07-229431 A

  However, the conventional control method has the following problems. In an internal combustion engine mounted on a vehicle, carbon or the like is easily generated at the time of combustion due to repeated low-temperature start-up in winter and the like, and the oil content in blow-by gas recirculates to intake air at high loads, The actual compression ratio may change over time due to adhesion / deposition on the piston crown. Further, when the piston ring or cylinder bore surface wears out, the air-fuel mixture easily blows through the crankcase, and the actual effective compression pressure may decrease. Due to such factors, it is inevitable that the condition of the internal combustion engine changes over time.

  Also, depending on the nature of the fuel used, the knocking limit may change relatively large. When using heavy fuel, the knocking limit increases, but when using light fuel, the knocking limit decreases. In addition, since it is sufficient that the fuel to be used changes for each fuel supply, a change in the margin with respect to the knock limit value occurs at a relatively short cycle with respect to the change on the internal combustion engine side with time.

  Due to such unavoidable changes over time, the target ignition timing and target set by referring to a map set in advance according to the engine operating state such as engine speed and required load in an actual internal combustion engine The compression ratio must be set with a sufficient margin so as not to cause damage to the internal combustion engine in the worst case in anticipation of a change with time with respect to the initial engine condition. For this reason, the target ignition timing and the target compression ratio become values on the retard side and low compression ratio side rather than the ignition timing and compression ratio near the knock limit to be originally set. Inevitably decreases.

  Moreover, even when a sufficient margin is provided in anticipation of these changes over time, the actual effective compression ratio has become higher than the initial expected range due to carbon adhesion, etc., that was initially assumed. In such a case, even if the target ignition timing and the target compression ratio that are determined in advance with a sufficient margin are used, there is a risk that knocking will always occur.

  With regard to ignition timing control, a knock sensor that detects the occurrence of knocking has been provided, and the ignition timing is advanced as much as possible within the range where knocking does not occur. A so-called trace knock control is known in which the ignition timing is retarded in order to quickly resolve this. Further, it is known that a fuel property or the like is estimated according to the degree of occurrence of knocking, and a setting map for a target ignition timing is switched, or the result is retained and reflected in the next and subsequent operations. However, with respect to the control of the engine compression ratio, and further the control combining the ignition timing and the compression ratio, sufficient studies and countermeasures have not yet been made, and improvements are desired.

  The present invention has been made in view of such problems, and has a variable compression ratio mechanism that changes the compression ratio of the internal combustion engine, and a knocking detection unit that detects the occurrence of knocking, and the engine operating state The basic target compression ratio is set based on the above, and in the case of a predetermined steady operation state, based on the detection signal of the knocking detection means, the target compression ratio is operated to the higher compression ratio side than the basic target compression ratio, The variable compression ratio mechanism is driven and controlled toward the target compression ratio.

  According to the present invention, the target compression ratio can be increased to near the limit at which knocking occurs in a predetermined steady operation state, and knocking can be prevented even when the effective compression ratio of the internal combustion engine decreases due to deterioration over time. The actual torque can be improved without being generated.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, a configuration example of a control device for an internal combustion engine according to the present invention will be described with reference to FIGS. 1 and 18. FIG. 18 shows a variable compression ratio which is a multi-link type piston-crank mechanism in which the piston 3 and the crank pin 8 of the crankshaft 7 are linked by a plurality of links as a variable compression ratio mechanism that makes the engine compression ratio of the internal combustion engine variable. The mechanism 21 is shown. The variable compression ratio mechanism 21 is known as disclosed in Japanese Patent Application Laid-Open No. 2003-90409 and the like, and only a brief description will be given here.

  The variable compression ratio mechanism 21 includes an upper link 5 having one end connected to a piston 3 sliding in the cylinder 2 of the cylinder block 1 via a piston pin 4, and a connection pin 6 connected to the other end of the upper link 5. The lower link 9 is rotatably connected to the crankpin 8 of the crankshaft 7 and one end is connected to the lower link 9 via the connection pin 10 in order to limit the degree of freedom of the lower link 9. A control link 11 that is coupled and supported at the other end by an engine body (engine fixed body) such as a cylinder block 1 so as to be swingable. The swing support position of the control link 11 is a control shaft 12. The eccentric cam portion (control eccentric shaft portion) 13 is variably controlled. The control shaft 12 is disposed in parallel with the crankshaft 7 and is rotatably supported by the cylinder block 1.

  When the rotational position of the control shaft 12 changes, the motion constraint condition of the lower link 9 by the control link 11 changes, and the stroke characteristics and engine compression ratio of the piston 3 can be changed continuously. The rotation angle of the control shaft 12 is changed and held by, for example, a hydraulic actuator 22. The actuator 22 operates according to the hydraulic pressure supplied from the hydraulic device 23. The engine control unit 20 outputs a control signal corresponding to a target compression ratio tε, which will be described later, to the hydraulic device 23, and controls the supply hydraulic pressure to drive-control the variable compression ratio mechanism 21 toward the target compression ratio tε. . This compression ratio control is performed based on engine operating conditions. Typically, the compression ratio control is performed toward the low compression ratio side so as to avoid knocking as the engine load increases. Note that the rotational position of the control shaft 12 may be changed and held by an electric actuator using a motor or the like instead of the hydraulic drive type.

  According to such a variable compression ratio mechanism 21, in addition to being able to change the engine compression ratio in a continuous and stepless manner according to the engine operating state, the piston stroke characteristic itself is brought close to a preferable characteristic, for example, a characteristic close to simple vibration. Can do. Further, by connecting the control link 11 to the lower link 9, the control shaft 12 can be disposed obliquely below the crankshaft 7 having a relatively large space, and the engine mountability is excellent.

  Referring to FIG. 1, various sensors 25 such as a crank angle sensor and an accelerator opening sensor detect signals related to an engine operating state such as an engine speed, an engine load, an intake negative pressure, an exhaust temperature, and the like. Output to the control unit 20. Based on these detection signals, the engine control unit 20 controls the hydraulic device 23 as well as an ignition device (ignition plug) 26 that sparks and ignites an air-fuel mixture in the combustion chamber formed above the piston 3 and a fuel injection device. Is output to control the ignition timing, fuel injection amount, fuel injection timing, and the like.

  The cylinder block 1 is provided with a knocking sensor 24 that detects the occurrence of knocking in the combustion chamber. The knocking sensor 24 is, for example, a piezoelectric element mounted on a washer, and detects knocking from the combustion pressure.

  2 and 3 are flowcharts showing a routine for setting the target ignition timing tADV and the target compression ratio tε according to the first embodiment of the present invention. These routines are stored by the engine control unit 20 and are repeatedly executed every predetermined period (for example, every 10 ms or every predetermined crank angle).

  First, the setting of the target ignition timing tADV will be described with reference to FIG. The ignition device 26 is driven and controlled toward the target ignition timing tADV set here. In step S11, the engine speed rNe1 is read. As is well known, the engine speed rNe1 is calculated based on detection signals from, for example, a crank angle sensor and a cam angle sensor. In step S12, the accelerator opening rAPO1 corresponding to the torque requested by the driver is read. The accelerator opening rAPO1 is detected by, for example, a known accelerator opening sensor. In step S13, a basic target ignition timing tADV0 is calculated. Specifically, based on the engine speed rNe1 and the accelerator opening degree rAPO1, for example, a basic target ignition timing setting map set and stored in advance as shown in FIG. To get. As shown in FIG. 4, the basic target ignition timing tADV0 is set to the advance side as the engine speed rNe1 increases, and to the retard side (retard) as the accelerator opening rAPO1 increases. As shown in FIGS. 12 to 14, the basic target ignition timing tADV0 has a predetermined margin ΔMG on the retard side with respect to the knocking limit so as not to cause knocking in consideration of changes over time and dimensional errors. It is a secured value. Therefore, depending on the engine operating conditions, the basic target ignition timing tADV0 is a value that deviates from the optimal ignition timing on the MBT line to the retard side.

  In step S14, it is determined whether a predetermined MBT (Minimum Advance for Best Torque) learning condition is satisfied. Specifically, it is determined whether or not a predetermined steady operation state in which changes in the accelerator opening rAPO1 and the engine speed rNe1 are small. When the MBT learning condition is not satisfied, that is, in a situation where the driving condition changes such as during acceleration or deceleration, the operation amount described later cannot be obtained accurately, so the learning end flag is set to 0 and the process proceeds to step S21. Then, the ignition timing manipulated variable is set to “0”. That is, except for the steady operation state, basically, the basic target ignition timing tADV0 is set as the target ignition timing tADV as it is. The learning end flag indicates whether or not learning control for each engine operating condition has already been performed. If “0”, learning has not yet been performed, and if “1”, learning has been completed. Represents that.

  If the MBT learning condition is satisfied, the process proceeds to step S15, and learning is performed at least once (may be multiple times) under the current engine operating condition so that learning is not performed more than necessary under the same engine operating condition. Judgment was made. Specifically, it is determined whether or not the learning end flag is 1. If learning has not yet been performed, the process proceeds from step S15 to step S16, and it is determined whether a compression ratio operation described later is being performed. Specifically, it is determined whether the compression ratio operation permission flag is 1. The compression ratio operation permission flag indicates permission / prohibition of the compression ratio operation, and indicates that “1” is permitted, and “0” is prohibited. When the compression ratio operation is permitted, the compression ratio operation is performed by a target compression ratio setting routine of FIG. If the compression ratio is not being operated, the process proceeds from step S16 to step S17, and based on the detection signal of the knocking sensor 24, it is determined whether knocking at a predetermined level / frequency has occurred.

  If knocking has occurred, the process proceeds to step S22, and the operation amount to the evolution zone side of the ignition timing is returned to the value immediately before the occurrence of knocking, specifically, the previous value before one calculation. In step S23, the learning end flag is set to 1. Therefore, the learning of the ignition timing ends when knocking occurs, and the operation amount immediately before the occurrence of knocking is held as the learned value.

  On the other hand, if it is determined in step S17 that knocking has not occurred, the process proceeds to step S18, where the operation amount to the advance side of the ignition timing is a predetermined maximum value θPmax (for example, 15 deg) corresponding to the optimal ignition timing. It is determined whether it has reached. If the maximum value θPmax has been reached, the process proceeds to step S24, and the compression ratio operation permission flag is set to 1. That is, the operation of the compression ratio is prohibited until the target ignition timing reaches the optimal ignition timing. If the maximum value θPmax has not been reached, the routine proceeds to step S19, where the manipulated variable of the ignition timing is calculated. This operation amount may be a fixed value set in advance, or may be set according to the engine speed rNe1, the accelerator opening rAPO1, or the like. In step S20, the target ignition timing tADV is set. Specifically, the basic target ignition timing tADV0 is calculated by adding the basic target ignition timing tADV0 and the ignition timing manipulated variable set in the above steps S19, S21, and S22.

  Next, the setting of the target compression ratio tε will be described with reference to FIG. In step S31, the engine speed rNe1 is read. In step S32, the accelerator opening degree rAPO1 corresponding to the torque requested by the driver is read. In step S33, a basic target compression ratio tε0 is calculated. Specifically, based on the engine speed rNe1 and the accelerator opening rAPO1, for example, a basic target compression ratio setting map as shown in FIG. 5 is looked up to obtain the basic target compression ratio tε0. To do. As shown in FIG. 5, the basic target compression ratio tε0 is set to be lower as the accelerator opening degree rAPO1 is higher, and the low compression ratio side is set so as not to cause knocking in consideration of changes over time and dimensional errors. To a value with a predetermined margin.

  In step S34, it is determined whether a predetermined MBT learning condition is satisfied. Specifically, it is determined whether or not a predetermined steady operation state in which changes in the accelerator opening rAPO1 and the engine speed rNe1 are small. If the MBT learning condition is not satisfied, that is, if the driving condition changes as during acceleration or deceleration, the process proceeds to step S40, and the compression ratio manipulated variable is set to zero. That is, except for the steady operation state, basically, the basic target compression ratio tε0 is set as the target compression ratio tε as it is. When the MBT learning condition is satisfied, the process proceeds to step S35, and it is determined whether the compression ratio operation permission flag is 1. As described above, this compression ratio operation permission flag is set to “1” only when the target ignition timing is set to the optimal ignition timing.

  If the compression ratio operation permission flag is 1, the process proceeds to step S36, and the operation amount to the high compression ratio side of the target compression ratio is calculated. This operation amount may be a fixed value set in advance, or may be set according to the engine speed rNe1, the accelerator opening rAPO1, or the like. In step S38, it is determined whether knocking at a predetermined level / frequency has occurred. If knocking has occurred, the routine proceeds to step 41, where the compression ratio manipulated variable is returned to the previous value before one calculation. For example, the operation amount added last time is subtracted. Then, the process proceeds to step S42, the learning end flag is set to “1”, and the compression ratio operation permission flag is set to 0 in step S43. Therefore, the manipulated variable of the target compression ratio immediately before the occurrence of knocking is held as the learning value.

  In step S39, the target ignition timing tε is set. Specifically, the target compression ratio tε is calculated by adding the ignition timing manipulated variable set in steps S36, S40, and S41 to the basic target compression ratio tε.

  6 and 7 are flowcharts showing the flow of setting control of the target ignition timing tADV and the target compression ratio tε according to the second embodiment of the present invention. Note that the same steps as those in the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted as appropriate. In the second embodiment, the basic target ignition timing tADV0 and the basic target compression ratio tε0 are corrected based on the learned value.

  First, the correction of the basic target ignition timing tADV0 will be described. As shown in FIG. 6, in step S13A, the basic target ignition timing tADV0 calculated in step S13 is reflected or added to the basic target ignition timing tADV0. The ignition timing tADV0 is updated.

  As shown in FIG. 8, the ignition timing learning value is stored and held as an ignition timing learning map according to the basic fuel injection amount Tp corresponding to the engine speed Ne and the accelerator opening rAPO1. This ignition timing learning map is updated by, for example, a routine shown in FIG. In step S51, it is determined whether or not to update the ignition timing learning map. For example, when the learning end flag is switched from “0” to “1”, the update of the ignition timing learned value is permitted, and the process proceeds to step S52, where the ignition timing learned value on the map is updated. Specifically, the map value corresponding to the engine speed Ne and the fuel injection amount Tp is updated to the ignition timing manipulated variable held as the learning value.

  Next, the correction of the basic target compression ratio tε0 will be described. As shown in FIG. 7, in step S33A, the basic target compression ratio tε0 calculated in step S33 is reflected, that is, added to the basic compression ratio tε0. The target compression ratio tε0 is updated. As shown in FIG. 10, the compression ratio learning value is stored and held in accordance with the basic fuel injection amount Tp corresponding to the engine speed Ne and the accelerator opening rAPO1 as a compression ratio learning map. This compression ratio learning map is updated by a routine shown in FIG. 11, for example. In step S53, it is determined whether or not to update the compression ratio learning map. For example, when the compression ratio learning end flag is switched from “0” to “1”, updating of the compression ratio learning map is permitted, the process proceeds to step S54, and the compression ratio learning map is updated. Specifically, the value on the compression ratio learning map corresponding to the engine speed Ne and the fuel injection amount Tp is updated to the value of the compression ratio manipulated variable held as the learned value.

  Next, the effect of the said Example is demonstrated with reference to drawings. Referring to FIGS. 12 and 13, basic target ignition timing tADV0 and basic target compression ratio tε0 are set with a sufficient margin ΔMG with respect to the knocking limit in consideration of changes over time, dimensional errors, and the like. According to the above embodiment, in the steady operation state, based on the detection signal of the knocking sensor 24, the target ignition timing tADV is optimally advanced along the MBT line on the advance side of the basic target ignition timing tADV0 as shown by the arrow Y1. While operating toward the ignition timing, and as indicated by the arrow Y2, the target compression ratio tε is operated to the higher compression ratio side than the basic target compression ratio tε0, so that the basic target ignition timing does not occur without causing knocking. The predetermined increase ΔTq and torque can be effectively improved with respect to the setting of tADV0 and basic target compression ratio tε0. Although not shown in the above routine, during the compression ratio operation, the ignition timing is controlled to maintain the optimal ignition timing, that is, the compression ratio is high within the range where the ignition timing can take the optimal ignition timing. Operated to the ratio side.

  Further, as shown in FIG. 14, when knocking occurs during operation toward the high compression ratio side in steady operation, the value immediately before knocking occurs (specifically, one calculation is performed) as shown by an arrow Y3. By setting the previous value) as the target ignition timing and the target compression ratio, it is possible to improve the torque performance to the maximum extent that knocking does not occur. Further, the operation amount immediately before the occurrence of knocking is stored as a learned value, and this learned value is reflected in the setting of the basic target ignition timing tADV0 and the basic target compression ratio tε0 from the next time onward, so that it can be quickly performed during the subsequent operation. A target ignition timing and a target compression ratio can be set appropriately, and torque improvement and knock avoidance performance can be improved.

  The technical ideas of the present invention that can be understood from the above description will be listed with reference to the drawings. However, the present invention is not limited to the configuration of the embodiment given the reference numerals, and includes various modifications and changes without departing from the spirit thereof.

  (1) A variable compression ratio mechanism that changes the compression ratio of the internal combustion engine, a knocking detection unit that detects the occurrence of knocking, and a control unit that drives and controls the variable compression ratio mechanism toward a target compression ratio. The control unit sets a basic target compression ratio based on the engine operation state, and, in a predetermined steady operation state, determines the target compression ratio based on the detection signal of the knocking detection means based on the basic target compression ratio. Also operate to the high compression ratio side. Therefore, the target compression ratio can be increased to near the limit at which knocking occurs in a predetermined steady operation state, and even when the internal combustion engine has fallen due to deterioration over time or the like, the effective compression ratio is reduced without causing knocking. Torque can be improved.

  (2) It has an ignition device capable of changing the ignition timing. Then, the basic target ignition timing is set based on the engine operating state, and the target ignition timing is advanced from the basic target ignition timing to the advance side based on the detection signal of the knocking detecting means in a predetermined steady operating state. Operate and drive-control the ignition device toward the target ignition timing. According to this configuration, the torque can be further improved by combining the advance of the ignition timing and the increase of the compression ratio.

  (3) The operation to the high compression ratio side by the variable compression ratio mechanism and the operation to the advance side of the ignition timing by the ignition device inevitably differ in responsiveness, and the optimum ignition timing also depends on the engine compression ratio. Therefore, if both operations are performed at the same time, knocking may occur transiently or the ignition timing may deviate from the optimal ignition timing, and the combination of compression ratio and ignition timing that provides the most torque can be obtained stably. Is difficult. Therefore, in order to obtain a stable combination of the compression ratio and the ignition timing at which the torque can be obtained, preferably, the target compression ratio is set until the target ignition timing reaches the optimal ignition timing in a predetermined steady operation state. The operation to the high compression ratio side is prohibited. That is, first, the target compression ratio is operated to the high compression ratio side only when the ignition timing having excellent responsiveness is advanced and the target ignition timing can be set to the optimal ignition timing without causing knocking.

  (4) More preferably, when the occurrence of knocking at a predetermined level is detected during the operation of the target compression ratio or the target ignition timing, the operation amount immediately before the occurrence of knocking is stored as a learning value, and the learning value is reflected. Thus, the basic target compression ratio and the basic target ignition timing are set. As a result, during the subsequent engine operation, it is possible to quickly set an appropriate target compression ratio and target ignition timing reflecting the learned value.

  (5) The variable compression ratio mechanism includes a lower link attached to a crankpin of a crankshaft, an upper link that links the lower link and a piston of an internal combustion engine, and a control shaft whose rotational position is changed and held by an actuator. And a control eccentric shaft portion provided eccentric to the control shaft, and a control link that links the control eccentric shaft portion and the lower link.

  (6) Referring to FIG. 15, means (B1) for calculating the basic target compression ratio in response to the operating condition signal of the internal combustion engine, and means (B9) for calculating the basic target ignition timing in response to the operating condition signal. The output of the actual torque detecting means (B6), the means (B4) for receiving the driving condition signal and permitting learning, the actual torque detecting means (B6) for receiving the driving condition signal and detecting the actual torque. In response to the means (B7) for determining the maximum torque and the outputs of (B7) and (B4), the target compression ratio is set higher than the basic target compression ratio while maintaining the MBT (optimum ignition timing). And means (B5) for learning the compression ratio manipulated variable and means (B2) for correcting (or switching) (B1) by the output of (B5). In response to the outputs of (B7) and (B4), the target ignition timing is operated toward the advanced ignition side with respect to the basic target compression ratio toward the optimum ignition timing at which MBT is achieved, and the ignition timing operation amount is learned. Means (B8) and means (B10) for correcting (or switching) (B9) by the output of (B8).

  Examples of the actual torque detection means (B6) include the knocking sensor 24 of the above-described embodiment. By adopting such a configuration, it becomes possible to operate in combination with the compression ratio and the ignition timing up to a value of MBT while observing the actual torque change. Compared with the case where the basic target compression ratio and the basic target ignition timing set with a margin are used as they are, the torque is greatly improved and the thermal efficiency can be increased.

  (7) As shown in FIG. 16, in addition to the configuration of FIG. 15, the knocking signal detection means (such as the knocking sensor 24) is inputted to the inputs of the target compression ratio learning means (B5) and the ignition timing learning means (B8). In this configuration, the output of B12) is used.

  By adopting such a configuration, when learning the MBT by operating the ignition timing and the compression ratio, it becomes possible to operate the ignition timing and the compression ratio while confirming whether knocking has actually occurred. Even under operating conditions where knocking occurs before MBT, a value near the knocking limit can be set, so that knocking occurs by increasing the ignition timing and compression ratio. Risk can be avoided, and at the same time, high torque can be ensured. Also in the operation region where knocking does not occur and MBT can be obtained, as in the example of FIG. 15, the basic target compression ratio and basic target ignition timing set with a sufficient margin for each normal operation region in advance. Compared with the case where the value of is used as it is, the torque is greatly improved and the thermal efficiency can be increased.

  (8) Referring to FIG. 17, there is a target compression ratio learned value holding means (B5-2) for holding and storing the output of the target compression ratio learning means (B5-1) as a learned value. The configuration is such that the target compression ratio is corrected (or switched) using the outputs of the learning values (B5-3) and (B1), and the output of the ignition timing learning means (B8-1) is held as the learning value. A configuration having a target ignition timing learned value holding means (B8-2) for storing and correcting (or switching) the ignition timing using the output of the learned values (B8-3) and (B9) of the output. It is what. By adopting such a configuration, it becomes possible to hold and store the manipulated variable obtained by manipulating the compression ratio and the ignition timing for the MBT learning as a learned value. Therefore, it is necessary to search for the MBT by learning again at the next driving. This makes it possible to quickly set the ignition timing / compression ratio at the MBT or knock limit, so that the effect of improving torque and increasing thermal efficiency can be further improved.

The system figure which shows an example of the control apparatus of the internal combustion engine which concerns on this invention. The flowchart which shows the setting routine of the target ignition timing which concerns on 1st Example of this invention. The flowchart which shows the setting routine of the target compression ratio which concerns on the said 1st Example. The characteristic view which shows an example of the setting map of basic target ignition timing. The characteristic view which shows an example of the setting map of a basic target compression ratio. The flowchart which shows the setting routine of the target ignition timing which concerns on 2nd Example of this invention. The flowchart which shows the setting routine of the target compression ratio which concerns on the said 2nd Example. The characteristic view which shows an example of an ignition timing learning value map. The flowchart which shows the update routine of the said ignition timing learning value map. The characteristic view which shows an example of a compression ratio learning value map. The flowchart which shows the update routine of the said compression ratio learning value map. The characteristic view for demonstrating the effect of the said Example. The characteristic view for demonstrating the effect of the said Example similarly. The characteristic view for demonstrating the effect of the said Example similarly. The control block diagram which shows the 1st aspect of this invention. The control block diagram which shows the 2nd aspect of this invention. The control block diagram which shows the 3rd aspect of this invention. 1 is a cross-sectional view showing an example of a variable compression ratio mechanism for an internal combustion engine according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Engine control part 21 ... Variable compression ratio mechanism 24 ... Knocking sensor (knocking detection means)
26 ... Ignition device

Claims (4)

A variable compression ratio mechanism for changing the compression ratio of the internal combustion engine;
Knocking detection means for detecting occurrence of knocking;
An ignition device capable of changing the ignition timing;
A control unit that drives and controls the variable compression ratio mechanism toward the target compression ratio and drives and controls the ignition device toward the target ignition timing ;
This control unit
Set the basic target compression ratio and basic target ignition timing based on the engine operating state,
In the steady operating state of Jo Tokoro, and when the knocking detecting means does not detect the occurrence of knocking, as well as the operation to the high compression ratio side than the basic target compression ratio the target compression ratio, the target ignition timing Is operated to the advance side with respect to the basic target ignition timing, and the operation to the high compression ratio side of the target compression ratio is prohibited until the target ignition timing reaches the optimal ignition timing. Engine control device. When the control unit detects the occurrence of knocking at a predetermined level during the operation of the target compression ratio or the target ignition timing, the control unit stores the operation amount immediately before the occurrence of knocking as a learning value, and reflects the learning value, 2. The control device for an internal combustion engine according to claim 1 , wherein the basic target compression ratio and the basic target ignition timing are set. The variable compression ratio mechanism includes a lower link attached to a crankpin of a crankshaft, an upper link that links the lower link and the piston of the internal combustion engine, a control shaft whose rotational position is changed and held by an actuator, The control device for an internal combustion engine according to claim 1 or 2 , further comprising: a control eccentric shaft portion eccentrically provided on the control shaft; and a control link that links the control eccentric shaft portion and the lower link. . A variable compression ratio mechanism for changing the compression ratio of the internal combustion engine;
Knocking detection means for detecting occurrence of knocking;
Possess an ignition device capable of change, the ignition timing,
In a control method for an internal combustion engine that drives and controls the variable compression ratio mechanism toward a target compression ratio and drives and controls the ignition device toward a target ignition timing ,
Set the basic target compression ratio and basic target ignition timing based on the engine operating state,
At a predetermined steady operating condition, and when the knocking detecting means does not detect the occurrence of knocking, the target compression ratio as well as the operation to the high compression ratio side than the basic target compression ratio, the basic target ignition timing Control of an internal combustion engine characterized in that operation to the advance side with respect to the target ignition timing and operation to the high compression ratio side of the target compression ratio are prohibited until the target ignition timing reaches the optimal ignition timing. Method.

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