JP2006161583A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of avoiding problems such as knocking of an engine or the like upon failure of a variable compression ratio mechanism. <P>SOLUTION: An abnormality determination part B51 determines whether there is an abnormality in the variable compression ratio mechanism 102 or not, and if there is an abnormality, determines what kind of an abnormality failure it is. A calculating part B52 calculates compression ratio eε for control in an abnormal time, using a detected compression ratio ε1 and the determination result in B51. In B53, when it is determined there is an abnormality in the variable compression ratio mechanism 102, the compression ratio eε calculated in B52 is selected as a compression ratio ε for control, and when no abnormality is detected in the variable compression ratio mechanism 102, the detected compression ratio ε1 is selected as the compression ratio ε for control. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  It is generally known that increasing the compression ratio improves the thermal efficiency of the engine. However, if the compression ratio is increased too much, knocking (abnormal combustion) occurs, so that the compression ratio cannot be increased much particularly in a high load region. Therefore, in an engine in which the compression ratio can be made variable, a technique for improving the fuel consumption rate without causing knocking by setting the target compression ratio large in the low load region and small in the high load region is disclosed in Patent Literature. Conventionally known by 1 etc.

Patent Document 2 discloses a technique for detecting a failure of a so-called variable compression ratio mechanism that varies the compression ratio of an internal combustion engine.
JP 7-229431 A JP 2001-182571 A

  However, in Patent Document 2, when the variable compression ratio mechanism that changes the compression ratio fails for some reason, a deviation occurs between the actual compression ratio and the detected compression ratio, and air amount control and ignition timing control are performed. There is a risk that knocking may occur frequently due to failure to perform properly.

  Therefore, the main object of the present invention is to avoid problems such as engine knocking when the variable compression ratio mechanism fails in an engine having a variable compression ratio mechanism capable of operating the compression ratio.

  The present invention includes a variable compression ratio mechanism that changes an engine compression ratio according to an engine operating state, and the variable compression ratio mechanism includes a compression ratio detection unit that detects an engine compression ratio, and the compression ratio detection unit The control apparatus for an internal combustion engine that performs various controls of the internal combustion engine using the detected compression ratio detected in step 1 has abnormality determination means for determining whether or not the variable compression ratio mechanism is abnormal, and the variable compression ratio mechanism is abnormal Is determined, the control of the internal combustion engine is performed using an abnormal control compression ratio obtained by adding a predetermined value to the detected compression ratio detected by the compression ratio detecting means.

  According to the present invention, when an abnormality occurs in the variable compression ratio mechanism, various types of control of the internal combustion engine are performed using the compression ratio for abnormality control, so that knocking occurs, extreme fuel consumption deterioration and operation Deterioration can be avoided.

  An embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing an outline of a system configuration of a control device for an internal combustion engine according to the present invention. The internal combustion engine includes a variable compression ratio mechanism 102 that changes the engine compression ratio according to the engine operating state. The variable compression ratio mechanism 102 is basically controlled by an engine control unit (hereinafter referred to as ECU) 31 so as to have a target compression ratio tε calculated according to the engine operating state.

  First, the variable compression ratio mechanism 102 will be described. The crankshaft 51 includes a plurality of journal portions 52 and a crankpin portion 53, and the journal portion 52 is rotatably supported by the main bearing of the cylinder block 50. The crankpin portion 53 is eccentric by a predetermined amount from the journal portion 52, and a lower link 54 is rotatably connected thereto.

  The lower link 54 is configured to be divided into two members on the left and right sides, and the crank pin portion 53 is fitted in a substantially central connecting hole.

  The upper link 55 has a lower end side rotatably connected to one end of the lower link 54 by a connecting pin 56 and an upper end side rotatably connected to a piston 58 by a piston pin 57. The piston 58 receives the combustion pressure and reciprocates in the cylinder 59 of the cylinder block 50. Note that an intake valve and an exhaust valve (not shown) are disposed on the upper portion of the cylinder 59.

  The control link 60 is pivotably connected at its upper end side to the other end of the lower link 54 by a connecting pin 61, and its lower end side can be pivoted to the lower part of the cylinder block 50 that forms part of the engine body via the control shaft 62. It is connected. Specifically, the control shaft 62 is rotatably supported by the engine body and has an eccentric cam portion 62a that is eccentric from the center of rotation, and the lower end portion of the control link 60 is rotatable on the eccentric cam portion 62a. It is mated.

  The rotation position of the control shaft 62 is controlled by a compression ratio control actuator 63 using an electric motor based on a control signal (corresponding to the target compression ratio tε) from the ECU 31.

  Further, the control shaft 62 is provided with a position detection sensor 32 for detecting the rotation position. The detection signal of the position detection sensor 32 is input to the ECU 31, and the current engine compression ratio (detection compression ratio ε1) of the variable compression ratio mechanism 102 is calculated in the ECU 31 based on the detection signal of the position detection sensor 32. ing. That is, the engine compression ratio (detection compression ratio ε1) is determined by the position detection sensor 32 and a calculation program in the ECU 31 that calculates the current engine compression ratio of the variable compression ratio mechanism 102 based on the sensor detection value of the position detection sensor 32. A compression ratio detecting means for detecting is provided. In addition, 33 in FIG. 1 is a knock sensor.

  In the variable compression ratio mechanism 102 using the multi-link type piston-crank mechanism as described above, when the control shaft 62 is rotated by the compression ratio control actuator 63, the center position of the eccentric cam portion 62a, particularly the engine main body. The relative position with respect to changes. Thereby, the rocking | fluctuation support position of the lower end of the control link 60 changes. When the swing support position of the control link 60 changes, the stroke of the piston 58 changes, and the position of the piston at the piston top dead center (TDC) increases or decreases. This makes it possible to change the engine compression ratio.

  A target compression ratio tε used for control of the variable compression ratio mechanism 102 is calculated in the ECU 31. 2 and 3 show the calculation procedure of the target compression ratio tε in a block diagram and a flowchart, respectively.

  First, a target torque tT1 as a required load is obtained from the accelerator opening APO and the engine speed Ne (B11 in FIG. 2, S11 in FIG. 3). Next, the target compression ratio tε of the variable compression ratio mechanism 102 is obtained from the target torque tT1 and the engine speed Ne (B12 in FIG. 2 and S12 in FIG. 3). Specifically, the target compression ratio tε is obtained using a map as shown in FIG. Further, as shown in FIG. 5, the target compression ratio tε is set so as to decrease as the target torque tT1 increases if the engine speed is constant.

  FIG. 6 is a block diagram showing a control procedure of the compression ratio control actuator 63 of the variable compression ratio mechanism 102.

  The detection compression ratio ε1 of the variable compression ratio mechanism 102 converts the sensor detection value of the position detection sensor 32 into units (B21), and performs upper and lower limit processing from the maximum compression ratio to the minimum compression ratio that can be realized by the variable compression ratio mechanism 102. It is calculated by applying (B22). Then, a control command value to the compression ratio control actuator 63 is determined according to the difference between the detected compression ratio ε1 and the target compression ratio tε (B23).

  Further, the ECU 31 performs various controls of the engine such as the target throttle opening degree and the ignition timing based on the compression ratio set by the variable compression ratio mechanism 102.

  FIG. 7 is a block diagram showing a calculation procedure of the target throttle opening performed by the ECU 31.

  In B31 which is a required load calculation unit, the target torque tT1 is calculated according to the accelerator opening APO and the engine speed Ne. Specifically, for example, the target torque tT1 is calculated using a map in which the target torque tT1 is assigned according to the accelerator opening APO and the engine speed Ne.

  In B32, the required air amount rP is calculated according to the target torque tT1 and the engine speed Ne. Specifically, for example, the required air amount rP is calculated using a map in which the required air amount rP is assigned according to the target torque tT1 and the engine speed Ne.

  In B33, an upper limit air amount tPmax, which is an air amount capable of avoiding knocking, is calculated according to the control compression ratio ε (details will be described later). The upper limit air amount tPmax is calculated using, for example, a map in which the control compression ratio ε and the upper limit air amount tPmax are allocated. The upper limit air amount tPmax is set so as to increase as the control compression ratio ε decreases.

  In B34, the required air amount rP calculated in B32 and the upper limit air amount tPmax calculated in B33 are compared, and the smaller one is set as the target air amount tP.

  In B35, the throttle opening that can realize the target air amount tP is set as the target throttle opening. In FIG. 7, B32 to B35 are the target throttle opening calculation unit.

  FIG. 8 is a block diagram showing a calculation procedure of the ignition timing performed by the ECU 31. In B41 which is an engine load calculation unit, the engine load T is calculated using the output value of the air flow meter and the engine speed Ne. Specifically, for example, the engine load T is calculated using a map in which the engine load is assigned according to the output value of the air flow meter and the engine speed Ne.

  Then, in the ignition timing calculation unit B42, the required ignition timing is calculated using the engine load T calculated in B41, the engine speed Ne, and the control compression ratio ε. The required ignition timing is calculated using, for example, a plurality of maps in which the engine load T and the engine speed Ne are assigned for each control compression ratio ε.

  FIG. 9 is a block diagram showing an outline of the calculation procedure of the control compression ratio ε described above. This control compression ratio ε is determined according to whether or not the variable compression ratio mechanism 102 is abnormal.

  The variable compression ratio mechanism abnormality determination unit B51 determines whether or not there is an abnormality in the variable compression ratio mechanism 102 and, if there is an abnormality, how it is abnormal. That is, in B51, the presence / absence and type of abnormality of the variable compression ratio mechanism 102 is determined.

  In B52 which is the control ratio calculation unit for abnormal control, the control ratio eε for abnormal control is calculated using the detected compression ratio ε1 and the determination result in B51.

  In B53, it is determined which one of the detected compression ratio ε1 and the abnormal control compression ratio eε is used as the control compression ratio ε. That is, in B53, when it is determined that there is an abnormality in the variable compression ratio mechanism 102, the abnormal-time control compression ratio eε calculated in B52 is selected as the control compression ratio ε, and the variable compression ratio mechanism 102 is selected. If there is no abnormality, the detection compression ratio ε1 is selected as the control compression ratio ε.

  FIG. 10 is a block diagram specifically showing a calculation procedure performed in the variable compression ratio mechanism abnormality determination unit (B51) of FIG. 9 described above.

  In B61 which is an actuator drive current time calculation means, a time during which the actuator drive current flowing through the compression ratio control actuator 63 is continuously larger than a predetermined value, that is, a drive current large time Imaxtime is measured. To do. In other words, the time during which the actuator drive current continuously increases is measured.

  In B62 which is a compression ratio deviation amount calculation means, Δε which is a deviation between the detected compression ratio ε1 and the target compression ratio tε is calculated.

  In B63 which is a compression ratio deviation time calculation means, a time during which Δε calculated in B62 is continuously larger than a predetermined value, that is, a deviation between the detected compression ratio ε1 and the target compression ratio tε. The time Δtime during which Δε is large is measured.

  In B64, which is a knocking frequency calculating means, the occurrence frequency of knocking is calculated based on the signal from the knock sensor 33.

  In B65 which is a variable compression ratio mechanism abnormality determination means, preliminary determination flags fNG1, fNG2 and fNG3 are determined based on inputs from B61, B63 and B64. Specifically, when the large drive current time Imaxtime is larger than a predetermined value, the preliminary determination flag fNG1 is set to “1”, and when it is equal to or less than the predetermined value, fNG1 is set to “0”. When Δε is larger than a predetermined value set in advance, fNG2 that is a preliminary determination flag is set to “1”, and when it is equal to or less than a predetermined value, fNG2 is set to “0”. When the occurrence frequency of knocking is larger than a predetermined value set in advance, the preliminary determination flag fNG3 is set to “1”, and when it is equal to or lower than the predetermined value, fNG3 is set to “0”.

  In B66 which is a failure mode determination means, a failure mode (details will be described later) of the variable compression ratio mechanism 102 is estimated using the preliminary determination flags fNG1, fNG2 and fNG3, and a determination flag FNG corresponding to the failure mode (details will be described later). ) Is output.

  FIG. 11 summarizes the correlation between the preliminary determination flags fNG1, fNG2, and fNG3 and the estimated failure mode.

  When the preliminary determination flags fNG1, fNG2, and fNG3 are all “0”, it is determined that the variable compression ratio mechanism 102 is normal and there is no abnormality, and the determination flag FNG is set to “0”.

  When the preliminary determination flag fNG1 is “1”, and fNG2 and fNG3 are “0”, it is determined that the variable compression ratio mechanism 102 is mechanically fixed, and it is determined that the compression ratio is not changed, and the abnormality is caused by mechanical fixation. The determination flag FNG is set to “1”. In this specification, the concept of mechanical fixation includes a case where the compression ratio cannot be changed due to malfunction of the compression ratio control actuator 63 due to disconnection or the like.

  When the preliminary determination flags fNG1 and fNG3 are “0” and fNG2 is “1”, the detection compression ratio ε1 is the minimum compression ratio of the variable compression ratio mechanism 102 due to the disconnection of the position detection sensor 32 (sensor disconnection). Abnormality), and the determination flag FNG is set to “2”.

  When the preliminary determination flags fNG1 and fNG2 are “0” and fNG3 is “1”, it is determined that the output range of the position detection sensor 33 has changed due to aging, so-called abnormality due to sensor drift, and the determination flag FNG is set to “3”. " Strictly speaking, the sensor drift of the position detection sensor 33 can be detected only when the detection compression ratio ε1 is shifted to the low compression side.

  When the preliminary determination flags fNG1 and fNG2 are “1” and fNG3 is “0”, it is determined that there is an abnormality due to the mechanical fixation described above, and the determination flag FNG is set to “1”.

  When the preliminary determination flags fNG1 and fNG3 are “1” and fNG2 is “0”, it is determined that there is an abnormality due to the sensor drift described above, and the determination flag FNG is set to “3”.

  When the preliminary determination flag fNG1 is “0”, and fNG2 and fNG3 are “1”, it is determined that the position detection sensor 33 is abnormal, and the determination flag FNG is set to “2”.

  When the preliminary determination flags fNG1, fNG2, and fNG3 are all “1”, it is determined that there is an abnormality due to disconnection of the position detection sensor 33, and the determination flag FNG is set to “2”.

  FIG. 12 is a flowchart specifically showing a calculation procedure performed in the above-described variable compression ratio mechanism abnormality determining means (B65 in FIG. 10).

  In S21, it is determined whether or not the large drive current time is greater than a predetermined value set in advance. If the drive current is large, the process proceeds to S22, where the preliminary determination flag fNG1 is set to “1”. The process proceeds to S23 with fNG1 set to “0”.

  In S23, it is determined whether or not Δtime is larger than a predetermined value set in advance. If it is larger, the process proceeds to S24, where the preliminary determination flag fNG2 is set to “1”, otherwise, the preliminary determination flag fNG2 is set to “1”. In the state of “0”, the process proceeds to S25.

  In S25, it is determined whether or not the occurrence frequency of knocking is larger than a predetermined value set in advance. If it is larger, the process proceeds to S26, and the preliminary determination flag fNG3 is set to “1”. The process ends with fNG3 set to “0”.

  FIG. 13 is a block diagram specifically illustrating a calculation procedure performed in the above-described abnormality control compression ratio calculation unit (B52) of FIG.

  In B71, which is a compression ratio extra amount calculating means, a compression ratio extra amount to be added to the detected compression ratio ε is determined in accordance with the above-described determination flag FNG, knocking strength (magnitude of the sensor output signal of the knock sensor), and the like.

  Specifically, when the determination flag FNG is “1”, the compression ratio addition amount is set to zero. When the determination flag FNG is “2”, the difference between the maximum compression ratio and the minimum compression ratio that can be realized by the variable compression ratio mechanism 102 is used as the compression ratio addition amount. When the determination flag FNG is “3”, the deviation amount of the detected compression ratio ε1 with respect to the actual compression ratio (actual compression ratio) due to the sensor drift described above is set as the compression ratio addition amount. This amount of deviation is calculated, for example, by obtaining a correlation with the knocking intensity in advance by experimental adaptation or the like and mapping it. FIG. 14 is an explanatory diagram summarizing the amount of compression ratio addition according to the determination flag FNG.

  In the embodiment of the present invention described above, the control compression ratio ε used for various controls of the internal combustion engine is determined according to whether or not the variable compression ratio mechanism 102 is abnormal.

  When the detection compression ratio ε1 is always used as the control compression ratio ε, when the position detection sensor 33 is disconnected, the detection compression ratio 1ε becomes the minimum compression ratio, and the target compression ratio tε is larger than the detection compression ratio ε1. Thus, the compression ratio control actuator 63 is controlled to increase the compression ratio. That is, as shown in FIG. 15, when the detected compression ratio ε stops moving at a small value, the compression ratio control actuator 63 is controlled to increase the compression ratio, so that the actual compression ratio of the variable compression ratio mechanism 102 is increased. The (actual compression ratio) is likely to be a high value. Therefore, when the detected compression ratio ε1 is used as the control compression ratio ε in such a state, a deviation occurs between the actual compression ratio (actual compression ratio) and the detected compression ratio ε1, and air amount control or ignition timing is generated. Control or the like is not appropriately performed, and knocking is likely to occur in a high load range.

  However, in this embodiment, when it is estimated that the position detection sensor 33 is disconnected (FNG = 2), the variable compression ratio mechanism 102 can be realized with respect to the detection compression ratio ε1, as shown in FIG. A value obtained by adding the difference between the maximum compression ratio and the minimum compression ratio is used as the control compression ratio ε. That is, the control compression ratio ε is set to the maximum compression ratio that can be realized by the variable compression ratio mechanism 102. Therefore, various controls using the control compression ratio ε are performed at the maximum compression ratio, the maximum air amount is reduced in the air amount control, and the retard side is set in the ignition timing control. The occurrence of knocking can be avoided.

  When the position detection sensor 33 is in the sensor drift state described above, and the detected compression ratio ε1 is estimated to be a smaller value than the actual compression ratio (actual compression ratio) (FNG = 3). As shown in FIG. 17, the control compression ratio ε1 is obtained by adding the amount of deviation of the detection compression ratio ε1 to the actual compression ratio (actual compression ratio) to the compression ratio. For this reason, the maximum air amount is reduced in the air amount control and the retard side is set in the ignition timing control, so that the occurrence of knocking can be reliably avoided. In addition, since various controls using the control compression ratio ε are performed in a state closer to the actual compression ratio (actual compression ratio), it is possible to minimize the reduction in fuel consumption and maximum output.

  When it is estimated that the compression ratio variable mechanism 102 fails and the compression ratio cannot be varied (FNG = 1), as shown in FIG. 18, the variable compression ratio mechanism 102 is prohibited from performing the variable compression ratio operation. The compression ratio is fixed, and the actual compression ratio ε1 is used as the control compression ratio ε. That is, the variable compression ratio mechanism 102 is not operated with the target compression ratio tε. Therefore, the amount of operation of the compression ratio control actuator 63 can be reduced, and the energy consumption can be reduced. When the determination flag FNG is “1”, there is no difference between the detected compression ratio ε1 and the target compression ratio tε, so that knocking can be avoided without adding the compression ratio.

  In the above-described embodiment, the detection compression ratio ε1 is used as the control compression ratio ε when the determination flag FNG is “1”, but the control compression ratio ε can be realized by the variable compression ratio mechanism 102. It is also possible to use a value obtained by adding a predetermined value to the maximum compression ratio or the detected compression ratio ε1 according to the knocking strength (see FIG. 19). When the determination flag FNG is “2”, the maximum compression ratio that can be realized by the variable compression ratio mechanism 102 is used as the control compression ratio ε, but the control compression ratio ε is knocked to the detected compression ratio ε1. Accordingly, a value obtained by adding a predetermined value can be used (see FIG. 19). Further, when the determination flag FNG is “3”, a value obtained by adding a predetermined value according to the knocking strength to the detected compression ratio ε1 is used as the control compression ratio ε, but the variable compression ratio mechanism is used as the control compression ratio ε. It is also possible to use the maximum compression ratio achievable with 102 (see FIG. 19).

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

(1) A variable compression ratio mechanism that changes the engine compression ratio according to the engine operating state is provided, and the variable compression ratio mechanism has compression ratio detection means for detecting the engine compression ratio,
A control apparatus for an internal combustion engine that performs various controls of the internal combustion engine using the detected compression ratio detected by the compression ratio detection means, and has an abnormality determination means for determining whether there is an abnormality in the variable compression ratio mechanism, and the variable compression ratio mechanism When it is determined that there is an abnormality in the engine, various controls of the internal combustion engine are performed using a compression ratio for abnormal control that is obtained by adding a predetermined value to the detected compression ratio detected by the compression ratio detecting means. As a result, when an abnormality occurs in the variable compression ratio mechanism, various controls of the internal combustion engine are performed using the compression ratio for abnormal control, so that knocking, extreme deterioration in fuel consumption, and drivability decrease are prevented. It can be avoided.

  (2) In the control device for an internal combustion engine according to (1), the compression ratio for abnormal control is a maximum compression ratio that can be realized by the variable compression ratio mechanism.

  (3) In the control device for an internal combustion engine according to (1), the abnormality determination unit can determine the type of abnormality of the variable compression ratio mechanism, and the predetermined value added to the detected compression ratio is: It is set according to the type of failure.

  As a result, various controls of the internal combustion engine are performed using the compression ratio for abnormal control according to the failure mode of the variable compression ratio mechanism, so that knocking, extreme deterioration in fuel consumption, and drivability deterioration are more effective. Can be avoided.

  (4) In the control device for an internal combustion engine according to (3), when the abnormality is determined to be large by the abnormality determination unit, the deviation between the actual compression ratio and the detected compression ratio of the internal combustion engine is large. Is the maximum compression ratio that can be realized by the variable compression ratio mechanism. As a result, various controls of the internal combustion engine using the compression ratio for abnormal control are performed at the equivalent of the maximum compression ratio, the maximum air amount is reduced in the air amount control, and set to the retard side in the ignition timing control. Thus, knocking can be reliably avoided. Moreover, it can avoid that the performance of the whole internal combustion engine deteriorates due to the failure of the variable compression ratio mechanism.

  (5) The control apparatus for an internal combustion engine according to (3) or (4), further including knocking detection means for detecting knocking of the internal combustion engine, wherein the actual determination ratio and the detected compression ratio of the internal combustion engine are detected by the abnormality determination means. At the time of an abnormality in which knocking occurs even though it is estimated that the deviation is small, a predetermined value to be added to the detected compression ratio is determined according to the knocking strength. As a result, the compression ratio for abnormal control becomes larger than the detected compression ratio, so the maximum air amount is throttled in the air amount control, and set to the retard side in the ignition timing control, so that knocking is reliably avoided. can do.

  (6) In the control apparatus for an internal combustion engine according to any one of the above (3) to (5), it is estimated that the deviation between the actual compression ratio and the detected compression ratio of the internal combustion engine is hardly caused by the abnormality determination means. In spite of this, when the compression ratio variable operation by the variable compression ratio mechanism is not possible, the compression ratio variable operation by the variable compression ratio mechanism is prohibited, and the detected compression ratio is set as the control compression ratio for abnormal control. Thereby, energy consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the outline of the system configuration | structure of the control apparatus of the internal combustion engine which concerns on this invention. The block diagram which shows the calculation procedure of target compression ratio t (epsilon). The flowchart which shows the calculation procedure of target compression ratio t (epsilon). The map figure for target compression ratio tε calculation. The map figure for target compression ratio tε calculation. The block diagram which shows the procedure of control of a compression ratio control actuator. The block diagram which shows the calculation procedure of target throttle opening. The block diagram which shows the calculation procedure of ignition timing. The block diagram which shows the outline of the calculation procedure of compression ratio (epsilon) for control. The block diagram which shows concretely the calculation procedure performed within the variable compression ratio mechanism abnormality determination part (B51) of FIG. Explanatory drawing which shows the correlation with the failure mode estimated with the preliminary | backup discrimination | determination flags fNG1, fNG2, and fNG3. The flowchart which shows concretely the calculation procedure performed within the variable compression ratio mechanism abnormality determination means (B65) of FIG. The block diagram which shows concretely the calculation procedure performed within the compression ratio calculation part (B52) for control at the time of abnormality of FIG. Explanatory drawing which put together the compression ratio addition amount according to the determination flag FNG. 9 is a timing chart showing an example of changes in accelerator opening, various compression ratios, and torque when the detected compression ratio ε1 is always used as the control compression ratio ε and the detected compression ratio ε stops moving at a small value. The timing chart which shows an example of the accelerator opening degree in the case of FNG = 2, various compression ratios, and the change of a torque. The timing chart which shows an example of the accelerator opening degree in the case of FNG = 3, various compression ratios, and the change of a torque. The timing chart which shows an example of the change of the accelerator opening degree in the case of FNG = 1, various compression ratios, and torque. Explanatory drawing which summarized the setting example of the control compression ratio (epsilon) set corresponding to a failure mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 31 ... Engine control unit 32 ... Position detection sensor 63 ... Compression ratio control actuator 102 ... Variable compression ratio mechanism

Claims (6)

A variable compression ratio mechanism that changes the engine compression ratio according to the engine operating state, and the variable compression ratio mechanism has compression ratio detection means for detecting the engine compression ratio;
In a control device for an internal combustion engine that performs various controls of the internal combustion engine using the detected compression ratio detected by the compression ratio detection means,
There is an abnormality determining means for determining whether there is an abnormality in the variable compression ratio mechanism, and when it is determined that there is an abnormality in the variable compression ratio mechanism, a predetermined value is added to the detected compression ratio detected by the compression ratio detecting means. A control apparatus for an internal combustion engine, which performs various controls of the internal combustion engine using the abnormal compression control ratio.   The control apparatus for an internal combustion engine according to claim 1, wherein the compression ratio for abnormal control is a maximum compression ratio that can be realized by the variable compression ratio mechanism.   The abnormality determination means is capable of determining the type of abnormality of the variable compression ratio mechanism, and the predetermined value added to the detected compression ratio is set according to the type of failure. 2. A control device for an internal combustion engine according to 1.   In the case of an abnormality in which the deviation between the actual compression ratio and the detected compression ratio of the internal combustion engine is estimated to be large by the abnormality determination means, the compression ratio for abnormal control is set to the maximum compression ratio that can be realized by the variable compression ratio mechanism. The control apparatus for an internal combustion engine according to claim 3. Having knocking detection means for detecting knocking of the internal combustion engine,
In the event of an abnormality in which knocking occurs despite the fact that the deviation between the actual compression ratio of the internal combustion engine and the detected compression ratio is estimated to be small by the abnormality determination means, the predetermined value added to the detected compression ratio depends on the knocking strength. The control apparatus for an internal combustion engine according to claim 3 or 4, wherein the control apparatus is determined as follows.   When the abnormality determination means estimates that there is almost no deviation between the actual compression ratio and the detected compression ratio of the internal combustion engine, the variable compression ratio mechanism is used when the variable compression ratio mechanism cannot be operated. 6. The control apparatus for an internal combustion engine according to claim 3, wherein the compression ratio variable operation is prohibited, and the detected compression ratio is set to a compression ratio for abnormal control.

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