JP5664081B2 - Control device for spark ignition internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a spark ignition type internal combustion engine.

In recent years, for the purpose of reducing fuel consumption and reducing CO ₂ emissions, the internal combustion engine is automatically stopped when the vehicle equipped with the internal combustion engine is stopped, and the internal combustion engine is automatically activated when the vehicle starts again. A control device for an internal combustion engine that performs control to be restarted (hereinafter referred to as “eco-run control”) has been developed. During such eco-run control, for example, when the vehicle is stopped and the amount of depression of the accelerator pedal by the driver is zero, the engine stop condition is satisfied, and the fuel supply from the fuel injection valve or the spark plug The ignition due to is stopped, and the rotation of the internal combustion engine is stopped. Thereafter, the engine restart condition is satisfied, for example, when the accelerator pedal is depressed, and the internal combustion engine is rotated again.

  When such an eco-run control is performed, if the internal combustion engine is always restarted using the starter motor when the engine restart condition is satisfied, the starter motor will be used too many times and the life of the starter motor will be increased. Becomes shorter. Further, since the battery charge / discharge load increases with the increase in use of the starter motor, a large capacity battery is required.

  Therefore, stop position control is performed to control the piston to stop at the target stop position when the operation of the internal combustion engine is automatically stopped, and fuel injection is performed to the cylinder in the middle of the expansion stroke while the engine is stopped. In addition, there is known a system in which ignition is performed and an internal combustion engine is started without using a starter motor by combustion of an air-fuel mixture accompanying the ignition. According to such an apparatus, the number of times the starter motor can be used can be reduced, and a large-capacity battery is not necessary.

  For example, in the apparatus described in Patent Document 1, the throttle valve opening is increased as fuel injection and ignition are stopped after the engine stop condition is satisfied, so that the in-cylinder charged air amount increases for each cylinder. . As a result, a large amount is added to a cylinder that is in the middle of the compression stroke when the engine is stopped (hereinafter referred to as a “compression stroke cylinder when stopped”) and a cylinder that is in the middle of the expansion stroke (hereinafter referred to as “expansion stroke cylinder when stopped”). In addition, almost the same amount of air is filled, so that when the engine is stopped, the piston is positioned near the middle position of the stroke.

JP 2004-293474 A

  By the way, a variable compression ratio mechanism capable of changing the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of the intake valve are provided, and the amount of intake air supplied into the combustion chamber is mainly used to close the intake valve. There is known a spark ignition type internal combustion engine which is controlled by changing the valve timing and has a higher mechanical compression ratio in engine low load operation than in engine high load operation. When the above-described eco-run control is applied to the spark ignition type internal combustion engine having such a configuration, the internal combustion engine is controlled by controlling the closing timing of the intake valve as one measure of the stop position control as described above. It is conceivable to perform stop position control of the piston when the operation is automatically stopped. However, in such stop position control, since the closing timing of the intake valve is changed in order to stop the piston at the target stop position, the actual compression ratio at the time of restart changes, and start failure due to insufficient compression or the like occurs. It can happen. By the way, even if the piston can be stopped at the target stop position, the pressure in the cylinder decreases due to air outflow from the combustion chamber while the engine is stopped, etc. In some cases, torque may not be obtained at restart.

  In view of the above problems, the present invention comprises a variable compression ratio mechanism capable of changing the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of the intake valve, and the amount of intake air supplied into the combustion chamber is reduced. A spark ignition type internal combustion engine that is controlled by changing the valve closing timing of the intake valve and has a higher mechanical compression ratio in engine low load operation than in engine high load operation, and directly injects fuel into the cylinder An in-cylinder fuel injection device and an ignition plug for igniting an air-fuel mixture in the cylinder, and the internal combustion engine is automatically stopped when a predetermined condition including at least a vehicle stop is satisfied. In a spark ignition type internal combustion engine controller that automatically restarts the internal combustion engine when the engine is no longer satisfied, the piston stop position when the engine is stopped is accurately controlled to an appropriate target stop position from the viewpoint of restartability To do Come, and an object thereof is to provide a control device for enabling and to be an internal combustion engine to thereby restart the engine restart condition is satisfied as soon as possible after and reliably the internal combustion engine without applying external force by use of such a starter motor.

According to the first aspect of the present invention, the intake system is provided with the variable compression ratio mechanism capable of changing the mechanical compression ratio and the variable valve timing mechanism capable of controlling the closing timing of the intake valve, and is supplied to the combustion chamber. A spark ignition internal combustion engine in which the amount of air is controlled by changing the closing timing of the intake valve and the mechanical compression ratio is higher during engine low load operation than during engine high load operation. An in-cylinder fuel injection device that performs injection and an ignition plug that ignites an air-fuel mixture in the cylinder, and the internal combustion engine is automatically stopped when at least a predetermined condition including vehicle stop is satisfied, In a spark ignition type internal combustion engine control device in which an internal combustion engine is automatically restarted when a predetermined condition is not satisfied, a predetermined piston is stopped at a target stop position when the internal combustion engine is automatically stopped Stop position control hand The stop position control means stops the piston at the target stop position by controlling the expansion ratio while keeping the actual compression ratio constant when the operation of the internal combustion engine is automatically stopped. And a restart control means for injecting and igniting fuel into the cylinder using the in-cylinder fuel injection device and the spark plug at the time of restart. Expansion stroke cylinder restarting means for performing fuel injection and ignition to the stop-time expansion stroke cylinder, and compression stroke cylinder restarting means for performing fuel injection and ignition to the stop-time compression stroke cylinder at the time of restarting, The compression stroke cylinder restarting means corrects the mechanical compression ratio to adjust the in-cylinder pressure based on the elapsed time from the stop at the time of restart, and restarts the internal combustion engine at the corrected mechanical compression ratio. perform, a spark-ignition internal combustion engine Your device is provided. The “expansion stroke cylinder at stop” refers to a cylinder that is in the middle of the expansion stroke when the engine is stopped (that is, a cylinder that is in the middle of the expansion stroke at the time of restart). The cylinder in the middle of the compression stroke when the engine is stopped (that is, the cylinder in the middle of the compression stroke at the time of restart) is shown.

  That is, in the invention described in claim 1, a spark ignition internal combustion engine having a variable compression ratio mechanism and a variable valve timing mechanism, the internal combustion engine is automatically stopped when a predetermined condition is satisfied, In a control device for a spark ignition type internal combustion engine in which the internal combustion engine is automatically restarted when the predetermined condition is not satisfied, the predetermined piston is moved to a target stop position when the internal combustion engine is automatically stopped. The stop position control means is configured to control the expansion ratio while keeping the actual compression ratio constant by the variable compression ratio mechanism and the variable valve timing mechanism. The piston is configured to stop at the target stop position. According to the control device for the spark ignition internal combustion engine of the present invention having such a configuration, the ignition is necessary for smooth restart by including the stop position control means for stopping the piston at the target stop position. The piston can be stopped at the target stop position where the performance and generated torque can be obtained, and the piston is stopped at the target stop position by controlling the expansion ratio while keeping the actual compression ratio constant. By configuring the piston, the piston can be stopped at the target stop position without changing the actual compression ratio when the internal combustion engine is automatically stopped, and the start failure due to insufficient compression or the like can be suppressed. It is possible to reliably restart the internal combustion engine as soon as possible after the restart condition of the internal combustion engine is satisfied without applying external force due to use.

According to the invention described in claim 2 , the compression stroke cylinder restarting means adjusts the positional relationship between the in-cylinder injection device and the piston in accordance with the engine coolant temperature and the fuel injection amount at the time of restarting. Accordingly, there is provided a control device for a spark ignition type internal combustion engine according to claim 1 , which further corrects the mechanical compression ratio.

According to a third aspect of the present invention, the compression stroke cylinder restarting unit is configured to calculate an in-cylinder pressure decrease amount based on an elapsed time from when the internal combustion engine is stopped, and the in-cylinder pressure decrease amount. The control device for the spark ignition type internal combustion engine according to claim 1 , wherein the mechanical compression ratio at the next restart is corrected based on the behavior of the engine speed after the restart to adjust the calculation error of the engine. .

  According to the invention described in each claim, the intake system is provided with a variable compression ratio mechanism capable of changing the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of the intake valve, and is supplied to the combustion chamber. A spark ignition internal combustion engine in which the amount of air is controlled by changing the closing timing of the intake valve and the mechanical compression ratio is higher during engine low load operation than during engine high load operation. An in-cylinder fuel injection device that performs injection and an ignition plug that ignites an air-fuel mixture in the cylinder, and the internal combustion engine is automatically stopped when at least a predetermined condition including vehicle stop is satisfied, In a spark ignition type internal combustion engine control device in which the internal combustion engine is automatically restarted when a predetermined condition is no longer satisfied, a target stop position at which the ignitability and generated torque necessary for smooth restart can be obtained. The piston is stopped In addition, when the internal combustion engine is automatically stopped, the piston can be stopped at the target stop position without changing the actual compression ratio. Thus, there is a common effect that the internal combustion engine can be restarted as soon as possible after the restart condition of the internal combustion engine is established without applying external force due to the use of the above.

1 is an overall view of a spark ignition internal combustion engine. It is a disassembled perspective view of a variable compression ratio mechanism. 1 is a schematic side sectional view of an internal combustion engine. It is a figure which shows a variable valve timing mechanism. It is a figure which shows the lift amount of an intake valve and an exhaust valve. It is a figure for demonstrating a mechanical compression ratio, an actual compression ratio, and an expansion ratio. It is a figure which shows the relationship between theoretical thermal efficiency and an expansion ratio. It is a figure for demonstrating a normal cycle and a super-high expansion ratio cycle. It is a figure which shows changes, such as a mechanical compression ratio according to an engine load. 1 is an overall view of an internal combustion engine to which the present invention is applied. It is a flowchart which shows one Embodiment of a stop position control routine. It is a flowchart which shows one Embodiment of the control routine at the time of restart.

  FIG. 1 shows a side sectional view of a spark ignition type internal combustion engine. Referring to FIG. 1, 1 is a crankcase, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is a spark plug disposed at the center of the top surface of the combustion chamber 5, and 7 is intake air. 8 is an intake port, 9 is an exhaust valve, and 10 is an exhaust port. The intake port 8 is connected to the surge tank 12 via the intake branch pipe 11. An in-cylinder fuel injection device 13 that directly injects fuel into the cylinder (inside the cylinder) is disposed around the inner wall surface of the cylinder head 3.

  The surge tank 12 is connected to an air cleaner 15 via an intake duct 14, and a throttle valve 17 driven by an actuator 16 and an intake air amount detector 18 using, for example, heat rays are disposed in an engine intake passage in the intake duct 14. Is done. The surge tank 12 is provided with a pressure sensor 23 for detecting the pressure in the surge tank 12. On the other hand, the exhaust port 10 is connected to a catalytic converter 25 containing, for example, a three-way catalyst via an exhaust manifold 24. The exhaust manifold 24 is disposed in the engine exhaust passage in the exhaust manifold 24 and detects an exhaust air-fuel ratio 26. Is placed.

  On the other hand, in the embodiment shown in FIG. 1, the piston 4 is positioned at the compression top dead center by changing the relative position of the crankcase 1 and the cylinder block 2 in the cylinder axis direction at the connecting portion between the crankcase 1 and the cylinder block 2. Is provided with a variable compression ratio mechanism A capable of changing the volume of the combustion chamber 5 when the engine is operated, and a variable valve timing capable of controlling the closing timing of the intake valve 7 in order to change the actual start timing of the compression action. A mechanism B is provided.

  2 is an exploded perspective view of the variable compression ratio mechanism A shown in FIG. 1, and FIG. 3 is a side sectional view of the internal combustion engine schematically shown. Referring to FIG. 2, a plurality of protrusions 50 spaced from each other are formed below both side walls of the cylinder block 2, and cam insertion holes 51 each having a circular cross section are formed in each protrusion 50. Has been. On the other hand, a plurality of protrusions 52 are formed on the upper wall surface of the crankcase 1 so as to be fitted between the corresponding protrusions 50 spaced apart from each other. Cam insertion holes 53 each having a circular cross section are formed.

  As shown in FIG. 2, a pair of camshafts 54 and 55 are provided, and on each camshaft 54 and 55, a circular cam 56 that is rotatably inserted into each cam insertion hole 51. It is fixed. These circular cams 56 are coaxial with the rotational axes of the camshafts 54 and 55. On the other hand, an eccentric shaft 57 arranged eccentrically with respect to the rotation axis of each camshaft 54, 55 extends between the circular cams 56 as shown by hatching in FIG. A cam 58 is eccentrically mounted for rotation. As shown in FIG. 2, the circular cams 58 are disposed between the circular cams 56, and the circular cams 58 are rotatably inserted into the corresponding cam insertion holes 53.

  When the circular cams 56 fixed on the camshafts 54 and 55 are rotated in opposite directions as indicated by solid arrows in FIG. 3A from the state shown in FIG. In order to move toward the lower center, the circular cam 58 rotates in the opposite direction to the circular cam 56 in the cam insertion hole 53 as shown by the broken arrow in FIG. 3A, and is shown in FIG. As described above, when the eccentric shaft 57 moves to the lower center, the center of the circular cam 58 moves below the eccentric shaft 57.

  3A and 3B, the relative positions of the crankcase 1 and the cylinder block 2 are determined by the distance between the center of the circular cam 56 and the center of the circular cam 58. The cylinder block 2 moves away from the crankcase 1 as the distance between the center and the center of the circular cam 58 increases. When the cylinder block 2 moves away from the crankcase 1, the volume of the combustion chamber 5 increases when the piston 4 is located at the compression top dead center. Therefore, by rotating the camshafts 54 and 55, the piston 4 is compressed at the top dead center. The volume of the combustion chamber 5 when it is located at can be changed.

  As shown in FIG. 2, in order to rotate the camshafts 54 and 55 in the opposite directions, a pair of worm gears 61 and 62 having opposite spiral directions are attached to the rotation shaft of the drive motor 59, respectively. Gears 63 and 64 that mesh with the worm gears 61 and 62 are fixed to the ends of the camshafts 54 and 55, respectively. In this embodiment, by driving the drive motor 59, the volume of the combustion chamber 5 when the piston 4 is located at the compression top dead center can be changed over a wide range. The variable compression ratio mechanism A shown in FIGS. 1 to 3 shows an example, and any type of variable compression ratio mechanism can be used.

  On the other hand, FIG. 4 shows the variable valve timing mechanism B attached to the end of the camshaft 70 for driving the intake valve 7 in FIG. Referring to FIG. 4, the variable valve timing mechanism B includes a timing pulley 71 that is rotated in the direction of an arrow by a crankshaft of an engine via a timing belt, a cylindrical housing 72 that rotates together with the timing pulley 71, an intake valve A rotating shaft 73 that rotates together with the driving camshaft 70 and is rotatable relative to the cylindrical housing 72, and a plurality of partition walls 74 that extend from the inner peripheral surface of the cylindrical housing 72 to the outer peripheral surface of the rotating shaft 73. And a vane 75 extending from the outer peripheral surface of the rotating shaft 73 to the inner peripheral surface of the cylindrical housing 72 between the partition walls 74, and an advance hydraulic chamber 76 on each side of each vane 75. A retarding hydraulic chamber 77 is formed.

  The hydraulic oil supply control to the hydraulic chambers 76 and 77 is performed by the hydraulic oil supply control valve 85. The hydraulic oil supply control valve 85 includes hydraulic ports 78 and 79 connected to the hydraulic chambers 76 and 77, a hydraulic oil supply port 81 discharged from the hydraulic pump 80, a pair of drain ports 82 and 83, And a spool valve 84 that performs communication cutoff control between the ports 78, 79, 81, 82, and 83.

  When the cam phase of the intake valve driving camshaft 70 should be advanced, the spool valve 84 is moved rightward in FIG. 4 and the hydraulic oil supplied from the supply port 81 is advanced via the hydraulic port 78. The hydraulic oil in the retard hydraulic chamber 77 is discharged from the drain port 83 while being supplied to the hydraulic chamber 76. At this time, the rotary shaft 73 is rotated relative to the cylindrical housing 72 in the direction of the arrow.

  On the other hand, when the cam phase of the intake valve driving camshaft 70 should be retarded, the spool valve 84 is moved to the left in FIG. 4, and the hydraulic oil supplied from the supply port 81 causes the hydraulic port 79 to move. The hydraulic oil in the advance hydraulic chamber 76 is discharged from the drain port 82 while being supplied to the retard hydraulic chamber 77. At this time, the rotating shaft 73 is rotated relative to the cylindrical housing 72 in the direction opposite to the arrow.

  If the spool valve 84 is returned to the neutral position shown in FIG. 4 while the rotating shaft 73 is rotated relative to the cylindrical housing 72, the relative rotating operation of the rotating shaft 73 is stopped, and the rotating shaft 73 is The relative rotation position at that time is held. Therefore, the variable valve timing mechanism B can advance and retard the cam phase of the intake valve driving camshaft 70 by a desired amount.

  In FIG. 5, the solid line shows the time when the cam phase of the intake valve driving camshaft 70 is advanced most by the variable valve timing mechanism B, and the broken line shows the cam phase of the intake valve driving camshaft 70 being the most advanced. It shows when it is retarded. Therefore, the valve opening period of the intake valve 7 can be arbitrarily set between the range indicated by the solid line and the range indicated by the broken line in FIG. 5, and therefore the closing timing of the intake valve 7 is also the range indicated by the arrow C in FIG. Any crank angle can be set.

  The variable valve timing mechanism B shown in FIG. 1 and FIG. 4 shows an example. For example, the variable valve timing that can change only the closing timing of the intake valve while keeping the opening timing of the intake valve constant. Various types of variable valve timing mechanisms, such as mechanisms, can be used. In the present invention, since the variable valve timing mechanism B is used to change the actual compression action start timing, the actual compression action can be changed without using the variable valve timing mechanism. Any type of actual compression action start time changing mechanism can be used as long as it is a start time changing mechanism.

  Next, the meanings of terms used in the present application will be described with reference to FIG. 6A, 6B, and 6C show an engine having a combustion chamber volume of 50 ml and a piston stroke volume of 500 ml for the sake of explanation. , (B), (C), the combustion chamber volume represents the volume of the combustion chamber when the piston is located at the compression top dead center.

  FIG. 6A explains the mechanical compression ratio. The mechanical compression ratio is a value mechanically determined only from the stroke volume of the piston and the combustion chamber volume during the compression stroke, and this mechanical compression ratio is expressed by (combustion chamber volume + stroke volume) / combustion chamber volume. In the example shown in FIG. 6A, this mechanical compression ratio is (50 ml + 500 ml) / 50 ml = 11.

  FIG. 6B describes the actual compression ratio. This actual compression ratio is a value determined from the actual piston stroke volume and the combustion chamber volume from when the compression action is actually started until the piston reaches top dead center, and this actual compression ratio is (combustion chamber volume + actual (Stroke volume) / combustion chamber volume. That is, as shown in FIG. 6B, even if the piston starts to rise in the compression stroke, the compression operation is not performed while the intake valve is open, and the actual compression is performed from the time when the intake valve is closed. The action begins. Therefore, the actual compression ratio is expressed as described above using the actual stroke volume. In the example shown in FIG. 6B, the actual compression ratio is (50 ml + 450 ml) / 50 ml = 10.

  FIG. 6C illustrates the expansion ratio. The expansion ratio is a value determined from the stroke volume of the piston and the combustion chamber volume during the expansion stroke, and this expansion ratio is expressed by (combustion chamber volume + stroke volume) / combustion chamber volume. In the example shown in FIG. 6C, this expansion ratio is (50 ml + 500 ml) / 50 ml = 11.

  Next, the super expansion ratio cycle used in the present invention will be described with reference to FIGS. FIG. 7 shows the relationship between the theoretical thermal efficiency and the expansion ratio, and FIG. 8 shows a comparison between a normal cycle and an ultrahigh expansion ratio cycle that are selectively used according to the load in the present invention.

  FIG. 8A shows a normal cycle when the intake valve closes near the bottom dead center and the compression action by the piston is started from the vicinity of the compression bottom dead center. In the example shown in FIG. 8A, the combustion chamber volume is 50 ml, and the stroke volume of the piston is 500 ml, as in the examples shown in FIGS. 6A, 6B, and 6C. As can be seen from FIG. 8A, in a normal cycle, the mechanical compression ratio is (50 ml + 500 ml) / 50 ml = 11, the actual compression ratio is almost 11, and the expansion ratio is also (50 ml + 500 ml) / 50 ml = 11. That is, in a normal internal combustion engine, the mechanical compression ratio, the actual compression ratio, and the expansion ratio are substantially equal.

  The solid line in FIG. 7 shows the change in the theoretical thermal efficiency when the actual compression ratio and the expansion ratio are substantially equal, that is, in a normal cycle. In this case, it can be seen that the theoretical thermal efficiency increases as the expansion ratio increases, that is, as the actual compression ratio increases. Therefore, in order to increase the theoretical thermal efficiency in a normal cycle, it is only necessary to increase the actual compression ratio. However, the actual compression ratio can only be increased to a maximum of about 12 due to the restriction of the occurrence of knocking at the time of engine high load operation, and thus the theoretical thermal efficiency cannot be sufficiently increased in a normal cycle.

  On the other hand, under such circumstances, it is considered to increase the theoretical thermal efficiency while strictly dividing the mechanical compression ratio and the actual compression ratio. As a result, the theoretical thermal efficiency is governed by the expansion ratio, and the actual compression ratio is compared to the theoretical thermal efficiency. Was found to have little effect. That is, if the actual compression ratio is increased, the explosive force is increased, but a large amount of energy is required for compression. Thus, even if the actual compression ratio is increased, the theoretical thermal efficiency is hardly increased.

  On the other hand, when the expansion ratio is increased, the period during which the pressing force acts on the piston during the expansion stroke becomes longer, and thus the period during which the piston applies the rotational force to the crankshaft becomes longer. Therefore, the larger the expansion ratio, the higher the theoretical thermal efficiency. The broken line ε = 10 in FIG. 7 indicates the theoretical thermal efficiency when the expansion ratio is increased with the actual compression ratio fixed at 10. Thus, the theoretical thermal efficiency when the expansion ratio is increased while the actual compression ratio ε is maintained at a low value, and the theoretical thermal efficiency when the actual compression ratio is increased with the expansion ratio as shown by the solid line in FIG. It can be seen that there is no significant difference from the amount of increase.

  Thus, if the actual compression ratio is maintained at a low value, knocking does not occur. Therefore, if the expansion ratio is increased while the actual compression ratio is maintained at a low value, the theoretical thermal efficiency is reduced while preventing the occurrence of knocking. Can be greatly increased. FIG. 8B shows an example where the variable compression ratio mechanism A and variable valve timing mechanism B are used to increase the expansion ratio while maintaining the actual compression ratio at a low value.

  Referring to FIG. 8B, in this example, the variable compression ratio mechanism A reduces the combustion chamber volume from 50 ml to 20 ml. On the other hand, the variable valve timing mechanism B delays the closing timing of the intake valve until the actual piston stroke volume is reduced from 500 ml to 200 ml. As a result, in this example, the actual compression ratio is (20 ml + 200 ml) / 20 ml = 11, and the expansion ratio is (20 ml + 500 ml) / 20 ml = 26. In the normal cycle shown in FIG. 8A, the actual compression ratio is almost 11 and the expansion ratio is 11, as described above. Compared with this case, only the expansion ratio is shown in FIG. 8B. It can be seen that it has been increased to 26. This is why it is called an ultra-high expansion ratio cycle.

  Generally speaking, in an internal combustion engine, the lower the engine load, the worse the thermal efficiency. Therefore, in order to improve the thermal efficiency during engine operation, that is, to improve fuel efficiency, it is necessary to improve the thermal efficiency when the engine load is low. Necessary. On the other hand, in the ultra-high expansion ratio cycle shown in FIG. 8B, since the actual piston stroke volume during the compression stroke is reduced, the amount of intake air that can be sucked into the combustion chamber 5 is reduced. The expansion ratio cycle can only be adopted when the engine load is relatively low. Therefore, in the present invention, when the engine load is relatively low, the super high expansion ratio cycle shown in FIG. 8B is used, and during the high engine load operation, the normal cycle shown in FIG. 8A is used.

Next, the overall operation control will be schematically described with reference to FIG.
FIG. 9 shows changes in the intake air amount, the intake valve closing timing, the mechanical compression ratio, the expansion ratio, the actual compression ratio, and the opening degree of the throttle valve 17 according to the engine load at a certain engine speed. . FIG. 9 shows that the average air-fuel ratio in the combustion chamber is theoretically based on the output signal of the air-fuel ratio sensor so that unburned HC, CO and NO _x in the exhaust gas can be simultaneously reduced by the three-way catalyst in the catalytic converter. This shows the case where feedback control is performed to the air-fuel ratio.

  As described above, the normal cycle shown in FIG. 8 (A) is executed during engine high load operation. Accordingly, as shown in FIG. 9, the expansion ratio is low because the mechanical compression ratio is lowered at this time, and the valve closing timing of the intake valve 7 is advanced as shown by the solid line in FIG. ing. At this time, the amount of intake air is large, and at this time, the opening degree of the throttle valve 17 is kept fully open, so that the pumping loss is zero.

  On the other hand, as shown in practice in FIG. 9, when the engine load becomes low, the intake valve closing timing is delayed to reduce the intake air amount accordingly. Further, at this time, as shown in FIG. 9, the mechanical compression ratio is increased as the engine load is lowered so that the actual compression ratio is kept substantially constant. Therefore, the expansion ratio is also increased as the engine load is lowered. At this time, the throttle valve 17 is kept fully open, and therefore the amount of intake air supplied into the combustion chamber 5 is controlled by changing the closing timing of the intake valve 7 regardless of the throttle valve 17. Has been.

  As described above, when the engine load is reduced from the engine high load operation state, the mechanical compression ratio is increased as the intake air amount is decreased while the actual compression ratio is substantially constant. That is, the volume of the combustion chamber 5 when the piston 4 reaches the compression top dead center is decreased in proportion to the decrease in the intake air amount. Therefore, the volume of the combustion chamber 5 when the piston 4 reaches the compression top dead center changes in proportion to the intake air amount. At this time, in the example shown in FIG. 9, the air-fuel ratio in the combustion chamber 5 is the stoichiometric air-fuel ratio, so the volume of the combustion chamber 5 when the piston 4 reaches the compression top dead center is proportional to the fuel amount. Will change.

When the engine load is further reduced, the mechanical compression ratio is further increased, and when the engine load is lowered to the medium load L ₁ slightly close to the low load, the mechanical compression ratio reaches a limit mechanical compression ratio that is a structural limit of the combustion chamber 5. When the mechanical compression ratio reaches the limit mechanical compression ratio, the mechanical compression ratio is held at the limit mechanical compression ratio in a region where the load is lower than the engine load L ₁ when the mechanical compression ratio reaches the limit mechanical compression ratio. Accordingly, the mechanical compression ratio is maximized and the expansion ratio is maximized at the time of low engine load operation and low engine load operation, that is, on the engine low load operation side. In other words, the mechanical compression ratio is maximized so that the maximum expansion ratio is obtained on the engine low load operation side.

On the other hand, in the embodiment shown in FIG. 9, when the engine load decreases to L ₁ , the closing timing of the intake valve becomes the limit closing timing that can control the intake air amount supplied into the combustion chamber 5. When the closing timing of the intake valve reaches the limit closing timing, the closing timing of the intake valve 7 is limited in a region where the load is lower than the engine load L ₁ when the closing timing of the intake valve reaches the closing timing. It is held at the closing timing.

When the closing timing of the intake valve 7 is held at the limit closing timing, the intake air amount can no longer be controlled by changing the closing timing of the intake valve. In the embodiment shown in FIG. 9, at this time, that is, in a region where the load is lower than the engine load L ₁ when the valve closing timing of the intake valve 7 reaches the limit valve closing timing, the fuel is supplied into the combustion chamber 5 by the throttle valve 17. The amount of intake air to be controlled is controlled, and the opening degree of the throttle valve 17 is made smaller as the engine load becomes lower.

On the other hand, as shown by the broken line in FIG. 9, the intake air amount can be controlled without depending on the throttle valve 17 by advancing the closing timing of the intake valve 7 as the engine load becomes lower. Accordingly, when expressing the case shown in FIG. 9 so as to include both the case indicated by the solid line and the case indicated by the broken line, in the embodiment according to the present invention, the valve closing timing of the intake valve 7 becomes smaller as the engine load becomes lower. It is moved in a direction away from the compression bottom dead center BDC until the limit valve closing timing L _{1 at} which the amount of intake air supplied into the combustion chamber can be controlled. Thus, the intake air amount can be controlled by changing the valve closing timing of the intake valve 7 as shown by the solid line in FIG. 9 or by changing it as shown by the broken line.

  Incidentally, as described above, the expansion ratio is 26 in the ultra-high expansion ratio cycle shown in FIG. The higher the expansion ratio, the better. However, as can be seen from FIG. 7, a considerably high theoretical thermal efficiency can be obtained if it is 20 or more with respect to the practically usable lower limit actual compression ratio ε = 5. Therefore, in the present invention, the variable compression ratio mechanism A is formed so that the expansion ratio is 20 or more.

  Below, the control apparatus of this invention is demonstrated in detail. FIG. 10 is an overall view of an internal combustion engine to which the present invention is applied. Referring to FIG. 10, the engine main body 100 includes a plurality of, for example, four cylinders 101a. Each cylinder 101a is connected to the surge tank 12 via a corresponding intake branch pipe. Each cylinder 101a is connected to a catalytic converter via an exhaust manifold. In the internal combustion engine shown in FIG. 10, combustion is performed in the order of # 1- # 3- # 4- # 2.

  An electric motor 128 can be connected to the crankshaft 127 via a clutch (not shown). The electric motor 128 can be formed of, for example, a so-called starter motor, or can be formed of an electric motor having a power generation function that is driven to rotate by the crankshaft 127 to generate electric power.

  The electronic control unit (ECU) 130 is composed of a digital computer, and a ROM (read only memory) 132, a RAM (random access memory) 133, a CPU (microprocessor) 134, and a power supply are always connected to each other by a bidirectional bus 131. B-RAM 135 (backup RAM), an input port 136, and an output port 137 are provided.

  In addition, an accelerator depression amount sensor 141 that generates an output voltage indicating the depression amount of the accelerator pedal is attached to an accelerator pedal (not shown). The output signal of the accelerator depression amount sensor 141 is input to the input port 136 via the corresponding AD converter 138. A crank angle sensor 142 for detecting the crank angle is attached to the crankshaft 127, and the crank angle sensor 142 is connected to the input port 136. In ECU 130, the engine speed (engine speed) is calculated based on the output of crank angle sensor 142. Further, the input port 136 is connected to an ignition (IG) switch 143 that generates an output pulse indicating that it is turned on, and a key switch 144 that generates an output pulse that indicates that it is turned on. . These ignition switch 143 and key switch 144 are operated by a driver of a vehicle equipped with an internal combustion engine. On the other hand, the output port 137 is connected to the actuator 16, spark plug 6, in-cylinder fuel injection device 13, various valve drive devices, electric motor, variable compression ratio mechanism A, and variable valve timing mechanism B through corresponding drive circuits 139. Is done.

  The internal combustion engine of the present embodiment, in normal operation, injects fuel during the intake stroke to make the air-fuel ratio of the air-fuel mixture substantially uniform over the entire combustion chamber and then ignites the air-fuel mixture, and ignition Operation can be performed in two combustion modes: a stratified combustion mode in which fuel is injected in the immediately preceding compression stroke and fuel is ignited only in the vicinity of the spark plug. These operation modes are selected based on the engine load and the engine speed. For example, in the operation region where the engine load is low and the engine speed is low, the engine is operated in the stratified combustion mode, and the engine load is high and the engine speed is low. In the operation region where the number is high, the operation is performed in the homogeneous combustion mode.

  Further, in the internal combustion engine of the present embodiment, when the ignition switch 143 is turned on by the driver, the internal combustion engine is started by the electric motor 128, and when the key switch 144 is turned off by the driver, the rotation of the internal combustion engine ( That is, the rotation of the crankshaft 127 is stopped.

  Further, in the internal combustion engine of the present embodiment, even when the key switch 144 is not turned off by the driver, the fuel injection from the in-cylinder fuel injection device is automatically performed when a predetermined engine stop condition is satisfied. And ignition by the spark plug is stopped, and as a result, the rotation of the internal combustion engine is stopped. Thereafter, when the engine restart condition is satisfied, the rotation of the internal combustion engine is automatically started again (that is, the crankshaft 127 of the internal combustion engine is rotated again). In this way, even when the key switch is not turned off by the driver, the control automatically stops and restarts the internal combustion engine under certain conditions (hereinafter, such control is referred to as “eco-run control”). In addition, reduction of fuel consumption and suppression of deterioration of exhaust emission can be realized.

  Here, the engine stop condition is satisfied when the engine load is zero (that is, the accelerator depression amount detected by the accelerator depression amount sensor 141 is zero) and the engine speed is low, or in addition to the above conditions This is the case where the speed of the vehicle equipped with the internal combustion engine is zero, and specifically includes the case where the vehicle is decelerating rapidly, the case where the vehicle is stopped, and the like. Therefore, the success or failure of the engine stop condition is detected based on the accelerator depression amount sensor 141, the crank angle sensor 142, the vehicle speed sensor (not shown) for detecting the speed of the vehicle equipped with the internal combustion engine, and the depression amount of the brake pedal by the driver. The ECU 130 makes a determination based on the output of a brake depression amount sensor (not shown) or the like.

  On the other hand, the case where the engine restart condition is satisfied is a case where the engine load is no longer zero or a case where the engine load is expected not to be zero. Specifically, the driver depresses the accelerator pedal. And when the brake pedal is depressed by the driver, the clutch pedal depressing operation or shift position is changed from N (neutral) or P (parking) to D (drive). This includes the case where a change operation is performed. Therefore, the success or failure of the engine restart condition is determined by the accelerator depression amount sensor 141, the vehicle speed sensor, the brake depression amount sensor, the clutch sensor (not shown) for detecting depression of the clutch pedal by the driver, and the shift position sensor (not shown). ) And the like based on the output.

  In the present embodiment, when the engine restart condition is satisfied after the rotation of the internal combustion engine is stopped by the eco-run control, the restart of the rotation of the internal combustion engine is performed without applying an external force to the internal combustion engine, that is, the driving force by the electric motor 128. Without being added, fuel injection and ignition are performed on a cylinder in the middle of an expansion stroke while the engine is stopped (hereinafter referred to as “expansion stroke cylinder when stopped”). Thus, energy consumption can be reduced by resuming the rotation of the internal combustion engine.

  The restart of the rotation of the internal combustion engine that is performed without applying an external force by using a starter motor or the like will be specifically described. When the engine stop condition is satisfied, fuel injection and ignition are stopped for all the cylinders, and stop position control is performed to control the piston to stop at the target stop position. Next, when the engine restart condition is satisfied, fuel is injected from the in-cylinder fuel injection device into the cylinder of the expansion stroke cylinder at the time of stop, and the injected fuel forms an air-fuel mixture with the air in the cylinder. Next, the mixture is ignited by the spark plug, and the mixture is ignited and combusted. When the air-fuel mixture is ignited and combusted in the expansion stroke cylinder at the time of stop, rotation of the internal combustion engine is started by the driving force obtained by this combustion.

  Further, when the engine restart condition is satisfied, in addition to the fuel injection and ignition for the stop-time expansion stroke cylinder as described above, a cylinder in the middle of the compression stroke while the engine is stopped (hereinafter referred to as “stop-time compression stroke cylinder”). Fuel injection from the in-cylinder fuel injection device. Such fuel injection is performed immediately after the engine restart condition is satisfied or after the engine restart condition is satisfied and immediately after the rotation of the internal combustion engine is started. Thereafter, as described above, when the internal combustion engine is rotated by the driving force due to combustion in the stop expansion stroke cylinder and the crank angle is at the compression top dead center for the stop compression stroke cylinder or immediately after the compression top dead center is exceeded. The cylinder is ignited by a spark plug. Thus, following the combustion in the stop expansion stroke cylinder described above, combustion is also performed in the stop compression stroke cylinder, and the operation of the internal combustion engine is started more reliably.

  Incidentally, as described above, when the piston stop position control is performed by controlling the closing timing of the intake valve and automatically stopping the operation of the internal combustion engine, the piston is stopped at the target stop position. Therefore, since the closing timing of the intake valve is changed as much as possible, the actual compression ratio at the time of restart may change, and a starting failure due to insufficient compression may occur.

  Based on this, in the present invention, when the operation of the internal combustion engine is automatically stopped, the piston is stopped at the target stop position by changing the expansion ratio while keeping the actual compression ratio constant. That is, the combustion chamber volume is changed so that the expansion ratio becomes a desired expansion ratio while adjusting the closing timing of the intake valve so as to keep the actual compression ratio constant even if the combustion chamber volume is changed, and the expansion stroke By adjusting the amount of change in the cylinder pressure per unit movement of the piston at the time, the load (resistance) against the rotation of the internal combustion engine after stopping the fuel injection and ignition is controlled, thereby bringing the piston to the target stop position Stop position control means for stopping the piston at the target stop position when the internal combustion engine is stopped is configured to stop.

  FIG. 11 is a flowchart showing an embodiment of a control routine by such a stop position control means. First, in step 201, it is determined whether or not a stop condition for the internal combustion engine is satisfied based on outputs from the accelerator depression amount sensor 141, the crank angle sensor 142, and the like. If it is determined that the stop condition is not satisfied, the control routine is terminated. On the other hand, if it is determined that the stop condition is satisfied, the process proceeds to step 202. In step 202, the fuel injection and ignition are stopped, the internal combustion engine is automatically stopped, and the process proceeds to step 203. In this embodiment, in order to stop the predetermined piston at the target stop position, the stop expansion stroke cylinder and the stop are stopped in this embodiment. The expansion ratio is controlled so that the piston in each cylinder of the hour compression stroke cylinder is stopped at the target stop position.

  In step 203, first, the target stop position of the piston is set from the engine speed immediately before the internal combustion engine is automatically stopped to calculate the target crank stop position, and the engine speed and expansion immediately before the stop are calculated. An actual crank estimated stop position that is a crank stop position at the time of actual stop estimated based on the ratio is calculated. Then, the target expansion ratio change amount is calculated according to the difference between the target crank stop position and the actual crank estimated stop position, and the target expansion ratio is calculated based on the target expansion ratio change amount. At this time, the closing timing of the intake valve is adjusted so that the actual compression ratio is kept constant even when the combustion chamber volume is changed to change the expansion ratio to the target expansion ratio. In the present embodiment, calculation of the target crank stop position and the actual crank estimated stop position based on the engine speed, the expansion ratio, etc. immediately before the internal combustion engine is automatically stopped is created in advance by analysis or test evaluation. Shall be done using the mapped map.

  According to such stop position control, when the fuel injection and ignition are stopped and the internal combustion engine is automatically stopped, the piston can be accurately stopped at the target stop position without changing the actual compression ratio. In the next restart, it is possible to start the internal combustion engine without using a starter motor or the like while suppressing a start failure due to insufficient compression or the like. That is, according to the stop position control means of the present invention, the stop position of the piston at the time of automatic engine stop can be accurately controlled to an appropriate position from the viewpoint of restartability, and by using a starter motor or the like. The internal combustion engine can be restarted as soon as possible after the restart condition of the internal combustion engine is established without applying external force.

  By the way, even if the piston can be stopped at the target stop position by the stop position control as described above, the pressure in the cylinder is reduced due to the outflow of air from the combustion chamber while the engine is stopped, etc. There may be a case where the ignitability and generated torque necessary for starting cannot be obtained at the time of restart. For example, a general piston structure has a piston ring that fills the gap between the piston and the cylinder, but air may flow out of the combustion chamber through the piston ring. Depending on the time during which the engine is stopped, the amount of outflow air becomes large, and the ignitability and generated torque necessary for smooth restart may not be obtained at the time of restart.

  Based on this, in one embodiment of the present invention, the fuel injection and ignition are stopped and the internal combustion engine is automatically stopped. And a restart-time control means for injecting and igniting fuel, and the restart-time control means includes an expansion stroke cylinder restarting means for performing fuel injection and ignition to the stop-time expansion stroke cylinder upon restart, and restart A compression stroke cylinder restarting means for performing fuel injection and ignition on the compression stroke cylinder at the time of stop, and the compression stroke cylinder restarting means is in-cylinder based on an elapsed time from the stop at the time of restart The mechanical compression ratio is corrected so as to adjust the pressure, and the internal combustion engine is restarted at the corrected mechanical compression ratio. In this embodiment, at the time of restart after the fuel injection and ignition are stopped and the internal combustion engine is automatically stopped, the outflow air amount from the combustion chamber is calculated based on the time during which the engine is stopped, A cylinder pressure drop amount is calculated from the outflow air amount. Then, based on the in-cylinder pressure drop amount, a correction amount of the mechanical compression ratio is calculated so that the in-cylinder pressure at the time of restart can be a desired pressure, and the mechanical compression ratio is corrected based on the correction amount. The internal combustion engine is restarted at the corrected mechanical compression ratio. The in-cylinder pressure drop may be calculated based on the time when the engine is stopped and the engine water temperature, and by providing an in-cylinder pressure sensor in each cylinder. It may be measured directly.

  When the mechanical compression ratio is corrected based on the in-cylinder pressure drop amount as described above, due to the change in the positional relationship between the in-cylinder fuel injection device and the piston due to the change in the mechanical compression ratio, It is possible that a large amount of fuel will be deposited, which may adversely affect exhaust emissions.

  Based on this, in one embodiment of the present invention, the fuel injection is performed at the corrected mechanical compression ratio based on the in-cylinder pressure drop in order to suppress the deterioration of exhaust emission caused by the fuel adhering to the piston due to the fuel injection. In consideration of the fuel adhering to the piston in the case where is executed, it is determined whether or not the correction of the mechanical compression ratio by the correction amount calculated based on the in-cylinder pressure drop amount can be executed. The degree of fuel adhesion to the piston by fuel injection can be specified by the engine coolant temperature, the fuel injection amount, and the like. For example, when the engine coolant temperature is high (that is, the engine temperature is high) and the fuel injection amount is small, the positional relationship between the in-cylinder fuel injection device and the piston upper surface is a closer relationship. The mechanical compression ratio can be increased. On the other hand, in the case where the engine coolant temperature is low and the fuel injection amount is large, if the mechanical compression ratio is increased, the degree of fuel adhesion to the piston due to fuel injection may increase. It is done.

  Therefore, in one embodiment of the present invention, the compression stroke cylinder restarting means adjusts the mechanical compression ratio, the engine coolant temperature, and the fuel injection amount after correction by the correction amount calculated based on the in-cylinder pressure drop amount. On the basis of determining whether or not to execute correction of the mechanical compression ratio by the correction amount calculated based on the in-cylinder pressure drop amount, and when it is determined that the correction of the mechanical compression ratio cannot be executed, A limit correction mechanical compression ratio that is a mechanical compression ratio that can avoid deterioration of exhaust emission due to fuel adhesion to the piston due to fuel injection is calculated, and the mechanical compression ratio is corrected to the limit correction mechanical compression ratio. That is, the compression stroke cylinder restarting means converts the mechanical compression ratio corrected based on the in-cylinder pressure drop amount as described above with the in-cylinder injection device according to the engine coolant temperature and the fuel injection amount at the time of restart. It is comprised so that it may correct | amend further in order to adjust the positional relationship with a piston.

  FIG. 12 is a flowchart showing an embodiment of the control routine at the time of restart as described above. First, in step 301, it is determined whether or not a restart condition for the internal combustion engine is established based on outputs from the accelerator depression amount sensor 141 and the vehicle speed sensor. If it is determined that the restart condition is not satisfied, the control routine is terminated. On the other hand, if it is determined that the restart condition is satisfied, the routine proceeds to step 302.

  In step 302, the outflow air amount from the combustion chamber is calculated based on the time during which the internal combustion engine has been stopped, and the in-cylinder pressure drop amount is calculated from the outflow air amount. Then, based on the in-cylinder pressure drop amount, a mechanical compression ratio correction amount (α) is calculated so that the in-cylinder pressure at the time of restart can be set as the target in-cylinder pressure.

  In step 303 following step 302, in-cylinder pressure reduction is performed in consideration of fuel adhesion to the piston when fuel injection is executed at a corrected mechanical compression ratio based on the correction amount (α) calculated in step 302. Whether or not the correction of the mechanical compression ratio can be executed is determined based on the mechanical compression ratio corrected by the correction amount (α) calculated based on the amount, the engine coolant temperature, and the fuel injection amount.

  If it is determined in step 303 that the correction of the mechanical compression ratio based on the correction amount (α) calculated in step 302 can be executed, the process proceeds from step 304 to step 306 and calculated in step 302. The corrected amount (α) is reflected in the mechanical compression ratio, and fuel injection and ignition are executed at the corrected mechanical compression ratio. On the other hand, if it is determined that the correction of the mechanical compression ratio cannot be performed, the process proceeds to step 307, and the mechanical compression ratio is set such that deterioration of exhaust emission due to fuel adhesion to the piston due to fuel injection can be avoided. Is calculated based on the engine coolant temperature and the fuel injection amount, and the mechanical compression ratio is controlled to the limit corrected mechanical compression ratio. That is, the mechanical compression ratio corrected based on the in-cylinder pressure drop amount in step 302 is further corrected to the limit corrected mechanical compression ratio calculated based on the engine coolant temperature and the fuel injection amount at the time of restart. In the subsequent step 308, fuel injection is executed at the limit corrected mechanical compression ratio. When fuel injection is executed in step 308, in step 309, the mechanical compression ratio is controlled to the corrected mechanical compression ratio based on the correction amount (α) calculated in step 302. Executed. According to such restart control, it is possible to suppress the influence on the restartability of the internal combustion engine caused by the outflow of air from the combustion chamber while the engine is stopped, and the fuel adheres to the piston by fuel injection. It is possible to suppress the influence on the exhaust emission caused by.

  Even when the above restart control is executed, the mechanical compression ratio correction amount (α) calculated in step 302 is theoretically calculated according to the time during which the internal combustion engine is stopped. The calculated in-cylinder pressure drop amount is calculated, and the calculated in-cylinder pressure drop amount may differ greatly from the actual in-cylinder pressure drop amount.

  Based on this, in one embodiment of the present invention, the compression stroke cylinder restarting means adjusts the error between the calculated in-cylinder pressure drop amount and the actual in-cylinder pressure drop amount. In order to adjust the calculation error of the internal pressure drop amount, the mechanical compression ratio is further corrected based on the behavior of the engine speed after restart. In this embodiment, the compression stroke cylinder restarting means calculates the mechanical compression ratio after correction based on the correction amount (α) calculated to make the in-cylinder pressure the target in-cylinder pressure in step 302 shown in FIG. The actual engine speed that is the actual engine speed when ignition is performed at the corrected mechanical compression ratio, and the theoretically calculated reference engine speed, which is the target in-cylinder pressure. Based on the reference engine speed, a correction value that can correct an error between the calculated in-cylinder pressure drop amount and the actual in-cylinder pressure drop amount is calculated as a learning value. Configured to reflect on restart. According to such restart control, it is possible to further improve restartability.

DESCRIPTION OF SYMBOLS 1 Crankcase 2 Cylinder block 3 Cylinder head 4 Piston 5 Combustion chamber 7 Intake valve 70 Camshaft for intake valve drive A Variable compression ratio mechanism B Variable valve timing mechanism

Claims (3)

A variable compression ratio mechanism capable of changing the mechanical compression ratio and a variable valve timing mechanism capable of controlling the closing timing of the intake valve are provided, and the amount of intake air supplied into the combustion chamber changes the closing timing of the intake valve. A spark ignition type internal combustion engine that is controlled by the engine and has a higher mechanical compression ratio at the time of engine low load operation than at the time of engine high load operation, and an in-cylinder fuel injection device that directly injects fuel into the cylinder, and a cylinder An ignition plug for igniting the air-fuel mixture, and the internal combustion engine is automatically stopped when a predetermined condition including at least a vehicle stop is satisfied, and when the predetermined condition is not satisfied, the internal combustion engine In the control device of the spark ignition internal combustion engine in which is automatically restarted,
When the internal combustion engine is automatically stopped, it is provided with stop position control means for stopping a predetermined piston at the target stop position, and the stop position control means is provided when the operation of the internal combustion engine is automatically stopped. The piston is stopped at the target stop position by controlling the expansion ratio while keeping the actual compression ratio constant ,
A restart control means for injecting and igniting fuel into the cylinder using the in-cylinder fuel injection device and the spark plug at the time of restart;
The restart-time control means performs expansion-stroke cylinder restart means for performing fuel injection and ignition for the stop-time expansion stroke cylinder during restart, and performs fuel injection and ignition for the stop-time compression stroke cylinder during restart. Compression stroke cylinder restarting means,
The compression stroke cylinder restarting means corrects the mechanical compression ratio to adjust the in-cylinder pressure based on the elapsed time from the stop at the time of restart, and restarts the internal combustion engine at the corrected mechanical compression ratio. A control device for a spark ignition type internal combustion engine. The compression stroke cylinder restarting means further corrects the mechanical compression ratio to adjust the positional relationship between the in-cylinder injection device and the piston according to the engine coolant temperature and the fuel injection amount at the time of restarting. 2. A control device for a spark ignition type internal combustion engine according to 1 . The compression stroke cylinder restarting means is configured to calculate an in-cylinder pressure drop amount based on an elapsed time from the stop of the internal combustion engine, and after the restart to adjust a calculation error of the in-cylinder pressure drop amount The control device for a spark ignition type internal combustion engine according to claim 1, wherein the mechanical compression ratio at the next restart is corrected based on the behavior of the engine speed.

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