JP4379273B2 - Internal combustion engine with variable compression ratio mechanism - Google Patents

Description

  The present invention relates to an internal combustion engine that changes a compression ratio by changing a relative distance between a cylinder head and a piston at a top dead center.

The compression ratio can be changed by changing the relative distance between the cylinder head and the piston at the top dead center, and the thermal efficiency of the internal combustion engine can be improved. A technique for correcting a valve timing shift associated with a change in the compression ratio by a valve timing changing device in an internal combustion engine that changes the compression ratio by moving the cylinder block in the cylinder axial direction with respect to the crankcase is known. (For example, see Patent Document 1).
JP 2003-206871 A JP 7-26981 A JP-T-2-503817 JP 2003-206770 A

  In order to change the compression ratio of the internal combustion engine, when changing the arrangement, size, etc. of some of the engine elements of the internal combustion engine, the relative relationship between the rotation of the crankshaft of the internal combustion engine and the position of the piston in the combustion cycle is shifted. There is a case. Here, when the intake / exhaust valve is driven by the power of the crankshaft or when the valve timing, which is the opening / closing timing of the intake / exhaust valve, is controlled based on the crank angle, the piston has a predetermined deadline such as the top dead center of the compression stroke. There is a possibility that the valve timing of the intake / exhaust valve deviates from the timing which should be originally with respect to the time at which it is located.

  According to Patent Document 1, it is possible to correct a valve timing shift. However, it is necessary to correct the valve timing shift every time the compression ratio changes, and it takes time to complete the correction. During correction, it becomes difficult to obtain an optimal valve timing, which may cause emission deterioration and engine output reduction.

  The present invention has been made in view of the various problems as described above, and an object thereof is to obtain an appropriate valve timing more quickly in an internal combustion engine having a variable compression ratio mechanism.

In order to achieve the above object, an internal combustion engine provided with a variable compression ratio mechanism according to the present invention is characterized by the following. That is,
In an internal combustion engine having a variable compression ratio mechanism for changing the compression ratio,
A valve timing changing device for changing the valve timing of at least one of the intake valve and the exhaust valve; and
A valve timing control device that feedback-controls the valve timing changing device so that an actual valve timing converges to a target valve timing based on an operating state of the internal combustion engine;
When the compression ratio is changed by the variable compression ratio mechanism, feedback gain correction means for changing the feedback gain in the feedback control of the valve timing changing device with respect to the feedback gain when the compression ratio is not changed;
It is provided with.

  The greatest feature of the present invention is that the valve timing shifts with the change of the compression ratio. Therefore, by changing the valve timing change rate, the valve timing shift can be quickly eliminated to obtain the optimum valve timing. is there.

  In the internal combustion engine described above, the compression ratio is changed by changing the elements involved in the compression ratio of the internal combustion engine, such as the piston stroke and the combustion chamber volume, by the variable compression ratio mechanism. However, there is a close relationship between the compression ratio and the operating state of the internal combustion engine, and if the compression ratio deviates from the compression ratio suitable for the operating state of the internal combustion engine, the fuel consumption and emission may be deteriorated. Therefore, in the above internal combustion engine, the compression ratio is changed based on the operating state of the internal combustion engine. As described above, the fuel consumption performance and the output performance are improved by changing the compression ratio according to the operating state of the internal combustion engine.

  Further, the valve timing changing device uses a predetermined angle as a reference value when changing the valve timing, and changes the valve timing by advancing the valve timing from the reference value according to the operating state of the internal combustion engine.

  In the internal combustion engine configured as described above, the valve timing control device controls the valve timing by feedback control so that the valve timing becomes optimum.

  On the other hand, by changing the compression ratio, changes are made to the elements involved in the compression ratio of the internal combustion engine, so the piston driven by the driving force transmitted from the crankshaft via one transmission route and the one transmission The valve timing of the drive valve that is driven by the driving force from the crankshaft by obtaining another transmission route different from the route is shifted, or the valve timing of the drive valve that is controlled according to the rotation angle of the piston and the crankshaft The valve timing may be shifted. In other words, as the compression ratio is changed, the valve timing of the drive valve with respect to the timing when the piston is in a predetermined position, for example, the timing at which compression top dead center is shifted, makes it difficult to ensure efficient intake and exhaust. As a result, the output of the internal combustion engine, fuel consumption deterioration, emission deterioration, etc. may occur, and it may be difficult to fully enjoy the effect of changing the compression ratio.

  In that respect, the feedback gain correction means changes the feedback gain (proportional gain of duty control) when the compression ratio of the internal combustion engine is changed, compared to when the compression ratio is not changed. That is, when changing the compression ratio of the internal combustion engine, the amount of change per unit time of the valve timing is changed. In this way, the valve timing can be changed quickly.

  Here, the feedback gain when the compression ratio is not changed is set to a value that can suppress overshoot of valve timing, deterioration of drivability, and the like. Therefore, if the feedback gain is increased when the compression ratio is changed, overshoot or the like may occur. However, when the compression ratio is changed, the valve timing is deviated compared to when the compression ratio is not changed. This affects the output performance, fuel consumption, and exhaust state of the internal combustion engine. It is better to get the valve timing. That is, by eliminating the occurrence of the valve timing deviation as early as possible, it is possible to avoid a decrease in the output of the internal combustion engine accompanying the change in the compression ratio.

  For this reason, in the present invention, the feedback gain correction means uses a feedback gain in feedback control of the valve timing changing device when the compression ratio is changed by the variable compression ratio mechanism, than a feedback gain when the compression ratio is not changed. May be set to a large value.

In this way, if the feedback gain is set to a large value, the valve timing is quickly changed, so that the deviation of the valve timing can be quickly eliminated.

  In the present invention, the time when the compression ratio is changed by the variable compression ratio mechanism may be a predetermined period from the start of changing the compression ratio. In this way, by changing the feedback gain for a predetermined period from the start of the compression ratio change, it is possible to quickly eliminate the valve timing shift accompanying the compression ratio change. Further, by returning the feedback gain after the predetermined period has elapsed, the occurrence of valve timing overshoot or the like when the compression ratio is not changed can be suppressed.

  Further, in the present invention, the variable compression ratio mechanism further includes a compression ratio change determination unit that determines whether or not to change the compression ratio, and the variable compression ratio mechanism has a compression ratio after the compression ratio change determination is made by the compression ratio change determination unit. The time when the compression ratio is changed by the variable compression ratio mechanism may be a predetermined period after the compression ratio change determination is made. By changing the feedback gain even after the compression ratio change determination is made and before the compression ratio is actually changed, the shift in valve timing can be eliminated more quickly.

  The predetermined period may be until the actual valve timing reaches the target valve timing.

  According to the internal combustion engine including the variable compression ratio mechanism according to the present invention, an appropriate valve timing can be quickly obtained when the compression ratio is changed.

  Specific embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a variable compression ratio internal combustion engine (hereinafter simply referred to as “internal combustion engine”) 1 in which the compression ratio is variable. In the present embodiment, in order to display the internal combustion engine 1 simply, some components are not shown. An intake pipe 19 is connected to the combustion chamber in the cylinder 2 via an intake port 18 provided in the cylinder head 10. The intake of the intake air into the cylinder 2 is controlled by the intake valve 5. Opening and closing of the intake valve 5 is controlled by rotational driving of the intake side cam 7. An exhaust pipe 21 is connected via an exhaust port 20 provided in the cylinder head 10. Exhaust discharge to the outside of the cylinder 2 is controlled by an exhaust valve 6. Opening and closing of the exhaust valve 6 is controlled by rotational driving of the exhaust side cam 8. Further, a fuel injection valve 17 is provided at the intake port 18, and a spark plug 16 is provided at the top of the cylinder 2. The piston 15 connected to the crankshaft 13 of the internal combustion engine 1 via the connecting rod 14 reciprocates in the cylinder 2.

  In the internal combustion engine 1, the compression ratio of the internal combustion engine 1 is changed by moving the cylinder block 3 relative to the crankcase 4 in the axial direction of the cylinder 2 by the variable compression ratio mechanism 9. That is, the variable compression ratio mechanism 9 is constituted by the cylinder block 3, the cylinder head 10 and the piston 15 by moving the cylinder head 10 together with the cylinder block 3 relative to the crankcase 4 in the axial direction of the cylinder 2. The volume of the combustion chamber is changed, and as a result, the compression ratio of the internal combustion engine 1 is variably controlled. For example, when the cylinder block 3 is relatively moved away from the crankcase 4, the combustion chamber volume increases and the compression ratio decreases.

The variable compression ratio mechanism 9 includes the shaft portion 9a, a cam portion 9b having a circular cam profile fixed to the shaft portion 9a while being eccentric with respect to the central axis of the shaft portion 9a, and the cam portion 9b. A movable bearing portion 9c having an outer shape and rotatable relative to the shaft portion 9a and attached in an eccentric state like the cam portion 9b, a worm wheel 9d provided concentrically with the shaft portion 9a, and a worm wheel 9d And a motor 9f that rotationally drives the worm 9e. The cam portion 9 b is installed in a storage hole provided in the cylinder block 3, and the movable bearing portion 9 c is installed in a storage hole provided in the crankcase 4. Here, the driving force from the motor 9f is transmitted to the shaft portion 9a via the worm 9e and the worm wheel 9d. Then, the cam block 9 b and the movable bearing portion 9 c in an eccentric state are driven, so that the cylinder block 3 is moved relative to the crankcase 4 in the axial direction of the cylinder 2.

  The internal combustion engine 1 is also provided with an electronic control unit (hereinafter referred to as “ECU”) 90 for controlling the internal combustion engine 1. The ECU 90 includes a CPU, a ROM, a RAM, and the like for storing various programs and maps to be described later, and controls the operating conditions of the internal combustion engine 1 according to the operating conditions of the internal combustion engine 1 and the driver's request. Unit.

  Here, the accelerator opening sensor 92 is electrically connected to the ECU 90, and the ECU 90 receives a signal corresponding to the accelerator opening, and calculates an engine load and the like required for the internal combustion engine 1 according to this signal. A crank position sensor 91 is electrically connected to the ECU 90. The ECU 90 receives a signal corresponding to the rotational angle of the output shaft of the internal combustion engine 1, and the engine rotational speed of the internal combustion engine 1, the engine rotational speed and the gears. The vehicle speed or the like of the vehicle on which the internal combustion engine 1 is mounted is calculated from the ratio or the like.

  Further, a motor 9f that constitutes the variable compression ratio mechanism 9 is electrically connected to the ECU 90. Then, the motor 9f is driven by a command from the ECU 90, and the compression ratio of the internal combustion engine 1 is changed by the variable compression ratio mechanism 9. The change in the compression ratio of the internal combustion engine 1 is performed based on the operating state of the internal combustion engine 1. For example, when the operating state of the internal combustion engine 1 is expressed by an engine load and an engine speed, the cylinder block 3 is connected to the crankcase 4 as the engine speed changes from a low engine load to a high engine load or from a low engine speed to a high engine speed. The motor 9f is driven in a direction away from the engine to shift the compression ratio of the internal combustion engine 1 from a high compression ratio to a low compression ratio.

  Next, the opening / closing operation of the intake valve 5 and the exhaust valve 6 in the internal combustion engine 1 and the opening / closing mechanism for performing the opening / closing operation will be described with reference to FIGS. 2 and 3 are diagrams mainly showing a mechanism of the valve timing control system of the internal combustion engine 1. FIG. 2A shows that the cylinder block 3 approaches the crankcase 4 and the compression ratio of the internal combustion engine 1 is relatively high. FIG. 2B shows a state in which the compression ratio (hereinafter simply referred to as “high compression ratio”) is reached. FIG. 2B shows the compression ratio (the compression ratio of the internal combustion engine 1 is relatively low) because the cylinder block 3 moves away from the crankcase 4. Hereinafter, the state of simply “low compression ratio” is shown. As shown in FIG. 2, the compression ratio of the internal combustion engine 1 is changed by the relative movement of the cylinder block 3 in the axial direction of the cylinder 2 by Δh. FIG. 3 is a diagram schematically showing the vicinity of the top of the cylinder head 10 with the intake valve 5 and the exhaust valve 6 as the center.

  In the internal combustion engine 1, the intake valve 5 is opened and closed by the intake side cam 7. The intake side cam 7 is attached to the intake side camshaft 22, and an intake side pulley 24 is provided at the end of the intake side camshaft 22. Further, a variable rotation phase mechanism (hereinafter referred to as “intake side VVT”) 23 that can change the relative rotation phase between the intake side camshaft 22 and the intake side pulley 24 is provided. The intake side VVT 23 controls the relative rotation phase between the intake side camshaft 22 and the intake side pulley 24 in accordance with a command from the ECU 90. Further, an intake side cam angle sensor 93 that detects the rotation angle of the intake side camshaft 22 is provided, and the intake side cam angle sensor 93 and the ECU 90 are electrically connected.

  The opening / closing operation of the exhaust valve 6 is performed by the exhaust side cam 8. The exhaust side cam 8 is attached to the exhaust side cam shaft 25, and an exhaust side pulley 27 is provided at the end of the exhaust side cam shaft 25. Further, a variable rotation phase mechanism (hereinafter referred to as “exhaust side VVT”) 26 that can change the relative rotation phase between the exhaust side camshaft 25 and the exhaust side pulley 27 is provided. The exhaust side VVT 26 controls the relative rotation phase between the exhaust side camshaft 25 and the exhaust side pulley 27 in accordance with a command from the ECU 90. Further, an exhaust side cam angle sensor 94 that detects the rotation angle of the exhaust side camshaft 25 is provided, and the exhaust side cam angle sensor 94 and the ECU 90 are electrically connected.

  The rotation of the intake camshaft 22 and the exhaust camshaft 25 is driven by the driving force of the crankshaft 13. Specifically, a timing belt 33 is hung on a crank pulley 32, an intake pulley 24, and an exhaust pulley 27 provided on the crankshaft 13, and the timing belt 33 is further provided on the crankcase 4 side. The first crankcase pulley 30, the second crankcase pulley 31 and the first cylinder block pulley 28 and the second cylinder block pulley 29 provided on the cylinder block 3 side are also engaged.

  The timing belt 33 is applied to the crank side pulley 32, the first crankcase side pulley 30, the first cylinder block side pulley 28, the intake side pulley 24, the exhaust side pulley 27, and the second cylinder block side pulley. 29, in order of the second crankcase pulley 31.

  The first crankcase side pulley 30 and the second crankcase side pulley 31 are in contact with the outer peripheral surface of the timing belt 33, and the other crank side pulley 32, first cylinder block side pulley 28, and intake side pulley 24. The exhaust side pulley 27 and the second cylinder block side pulley 29 are in contact with the inner peripheral surface of the timing belt 33.

  In this manner, the intake side camshaft 22 and the exhaust side camshaft 25 are driven to rotate by the driving force of the crankshaft 13, so that the intake side cam 7 and the exhaust side cam 8 cause the intake valve 5 and the exhaust valve 6 to move. Opening and closing operations are performed.

  Here, when the compression ratio of the internal combustion engine 1 is changed by the variable compression ratio mechanism 9, for example, the state is changed from the high compression ratio state shown in FIG. 2 (a) to the low compression ratio state shown in FIG. 2 (b). When this is done, the cylinder block 3 relatively moves in the direction away from the crankcase 4 as described above. Accordingly, the first cylinder block side pulley 28 and the second cylinder block side pulley 29 provided in the cylinder block 3 also move in accordance with the change of the compression ratio. As a result, the length L1 of the timing belt 33 between the first crankcase side pulley 30 and the first cylinder block side pulley 28 and the second crankcase side pulley 31 and the second cylinder block side pulley 29 are between. The length L2 of the timing belt 33 applied to is changed with the change of the compression ratio. With such a configuration, even if the cylinder block 3 moves, the total length of the timing belt 33 does not change.

  In the internal combustion engine 1, the relationship between the crank angle and the cam angles of the intake and exhaust valves 5 and 6 is based on signals from the crank position sensor 91, the intake side cam angle sensor 93, and the exhaust side cam angle sensor 94. The intake phase VVT 23 and the exhaust side VVT 26 feedback control the rotational phases of the intake side camshaft 22 and the exhaust side camshaft 25 so as to achieve an appropriate relationship.

In this embodiment, the intake side VVT 23 and the exhaust side VVT 26 are controlled according to how many times the intake side camshaft 22 and the exhaust side camshaft 25 are rotated from the most retarded position. That is, the position at which the intake side camshaft 22 and the exhaust side camshaft 25 are most retarded (hereinafter referred to as the most retarded position) is set as a reference position, and the reference position is used in accordance with the operating state of the internal combustion engine 1. The angles of the intake side camshaft 22 and the exhaust side camshaft 25 are advanced. The advance amount from the reference position is stored in the ECU 90 in advance as a map of the relationship between the operating state of the internal combustion engine 1 (for example, the engine speed and the engine load) and the advance amount. It can be obtained by substituting the operating state of the internal combustion engine 1.

  However, in the internal combustion engine 1 according to this example, when the state of the high compression ratio shown in FIG. 2 (a) is changed to the state of the low compression ratio shown in FIG. 2 (b), the timing belt length L1 becomes shorter. The timing belt length L2 becomes longer. As a result, the phases of the intake side pulley 24 and the exhaust side pulley 27 when the crankshaft 13 is at a specific rotation angle, in other words, when the position of the piston 15 is at the top dead center of the compression stroke, which is a specific position, etc. However, the high compression ratio state shown in FIG. 2 (a) is different from the low compression ratio state shown in FIG. 2 (b). That is, when the high compression ratio state shown in FIG. 2A is used as a reference, in the low compression ratio state shown in FIG. 2B, the rotation phases of the intake side pulley 24 and the exhaust side pulley 27 are shifted by ΔTv.

  Therefore, the valve timings of the intake valve 5 and the exhaust valve 6 with respect to the timing when the piston position is at the top dead center of the compression stroke are the high compression ratio state shown in FIG. 2 (a) and the low compression ratio state shown in FIG. 2 (b). However, there is a possibility that the valve timing may deviate from an appropriate timing as the compression ratio is changed. That is, as a result of the change of the compression ratio, there is a possibility that the valve timing suitable for the combustion performed in the cylinder 2 cannot be obtained.

  Here, the rotational phases of the intake side pulley 24 and the exhaust side pulley 27 are feedback-controlled by the intake side VVT 23 and the exhaust side VVT 26, thereby correcting the rotational phase shift between the intake side pulley 24 and the exhaust side pulley 27. However, if only relying on feedback control, it takes time to converge to an appropriate valve timing.

  In that respect, in the valve timing control system of the internal combustion engine 1 according to the present embodiment, the change rate of the valve timing is increased when the compression ratio is changed. That is, the proportional gain of duty control is increased.

  Since the intake side pulley 24 and the exhaust side pulley 27 are interlocked with the crankshaft 13 via the timing belt 33, the rotation phase of the intake side VVT 23 and the exhaust side VVT 26 changes the rotation angle of the crankshaft 13. The relative relationship between the rotation angles of the intake side camshaft 22 and the exhaust side camshaft 25 is quickly changed, and the valve timings of the intake valve 5 and the exhaust valve 6 with respect to the piston position of the piston 15 become appropriate timings.

  Here, FIG. 4 is a diagram showing the relationship between the difference between the target value of the valve timing and the actual measurement value and the proportional gain of the duty control of the valve timing. A solid line indicates a time when the compression ratio is changed (hereinafter referred to as a compression ratio change), and a broken line indicates a time when the compression ratio is not changed (hereinafter referred to as a normal time). When the difference between the target value of the valve timing and the actual measurement value is the same when the compression ratio is changed and when the compression ratio is changed, the proportional gain is higher than when the compression ratio is changed (for example, point A in FIG. 4). The middle point B) is set to a larger value.

  FIG. 5 is a diagram showing the relationship between the duty ratio when the valve timing is changed and the operating speeds of the intake side VVT 23 and the exhaust side VVT 26. The operating speeds of the intake side VVT 23 and the exhaust side VVT 26 are the rotational speed when the relative rotational phase between the intake side camshaft 22 and the intake side pulley 24 is changed, and the exhaust side camshaft 25 and the exhaust side pulley 27. The rotation speed when changing the relative rotation phase of.

  The duty ratio at the time of changing the compression ratio is larger than normal (for example, point A in FIG. 5), and the operating speeds of the intake side VVT 23 and the exhaust side VVT 26 are fast (for example, point B in FIG. 5).

  FIG. 6 is a time chart showing changes in the advance amount of the intake side VVT 23 and the exhaust side VVT 26 when the compression ratio is changed. The “target value” is the advance amount of the intake side VVT 23 and the exhaust side VVT 26 determined by the ECU 90 according to the operating state of the internal combustion engine 1. “Normal time” indicates a case where the duty control of the intake side VVT 23 and the exhaust side VVT 26 is performed using the same proportional gain as in the normal time even when the compression ratio is changed. Further, “when the compression ratio is changed” indicates a case where duty control is performed using the proportional gain when the compression ratio is changed according to the present embodiment.

  In “normal time” shown in FIG. 6, the proportional gain is set to a small value as shown in FIG. 4 in order to improve drivability, so the rate of change of the advance amount is small. On the other hand, in “when the compression ratio is changed”, since the proportional gain is set to a large value in order to quickly change the advance amount to the vicinity of the target value, the rate of change of the advance amount is large. Note that the magnitude of the proportional gain when the compression ratio is changed can be experimentally determined so that the advance amount overshoots, the drivability deteriorates, and the exhaust state is as large as possible within an allowable range. .

  Next, a control for adjusting the valve timings of the intake valve 5 and the exhaust valve 6 when the compression ratio of the internal combustion engine 1 is changed by the variable compression ratio mechanism 9 (hereinafter referred to as “compression ratio change control”) is shown in FIG. 7 will be described. Note that the compression ratio change control in this embodiment is a routine that is repeatedly executed in a constant cycle.

  First, in S101, the ECU 90 detects the operating state of the internal combustion engine 1. This operating state is an operating state related to the combustion in the cylinder 2, and is a basic item for determining whether or not the compression ratio of the internal combustion engine 1 is suitable for the combustion. In the present embodiment, the operating state of the internal combustion engine 1 is detected based on the engine rotation speed obtained based on the signal from the crank position sensor 91 and the engine load obtained based on the signal from the accelerator opening sensor 92. . In addition, the operating state may be detected based on the intake air amount, the coolant temperature, or the like in the internal combustion engine 1. When the process of S101 ends, the process proceeds to S102.

  In S102, the ECU 90 calculates a compression ratio most suitable for combustion performed in the internal combustion engine 1 (hereinafter referred to as “optimal compression ratio”) based on the operating state of the internal combustion engine 1 detected in S101. Specifically, the relationship between the operating state of the internal combustion engine 1 determined by the engine speed and the engine load and the optimum compression ratio in each operating state is obtained in advance by experiments or the like, and this relationship is expressed in the form of a control map. It stores in ECU90. In S102, the optimal compression ratio is calculated by accessing the control map using the operating state of the internal combustion engine 1 as a parameter. When the process of S102 ends, the process proceeds to S103.

  In S103, the ECU 90 performs relative movement between the cylinder block 3 and the crankcase 4 so that the compression ratio of the internal combustion engine 1 becomes the optimum compression ratio by the variable compression ratio mechanism based on the optimum compression ratio calculated in S102. When the process of S103 ends, the process proceeds to S104.

In S104, the ECU 90 reads the proportional gain from the duty control proportional gain map set for changing the compression ratio. Here, a map indicated by a solid line in FIG. 4 is stored in advance in the ECU 90, and a proportional gain is obtained by substituting the difference between the target value and the actual measurement value into the map. The target value is obtained from the operating state of the internal combustion engine 1, and the actual measurement value can be obtained from the output signals of the intake side cam angle sensor 93 and the exhaust side cam angle sensor 94. Further, the map indicated by the solid line in FIG. 4 is obtained in advance by experiments or the like and stored in the ECU 90. When the process of S104 ends, the process proceeds to S105.

  In S105, the ECU 90 determines whether or not the deviation between the target values of the advance amounts of the intake side camshaft 22 and the exhaust side camshaft 25 and the actually measured values has been eliminated. For example, if the change amount of the advance amount within a predetermined time is within the allowable range, it is assumed that there is no difference between the target value of the advance amount of the intake side camshaft 22 and the exhaust side camshaft 25 and the measured value. It is determined that the deviation has been eliminated. Further, the deviation may be eliminated after a predetermined period has elapsed since the start of changing the compression ratio. Further, the deviation may be eliminated after a predetermined period from the start or end of any of the processes in steps S101 to S104.

  If an affirmative determination is made in S105, the process proceeds to S106, whereas if a negative determination is made, the process returns to S105.

  In S106, the ECU 90 reads the proportional gain from the map of the proportional gain of the duty control set for the normal time. Here, the broken line portion of the map shown in FIG. 4 is stored in advance in the ECU 90, and a proportional gain is obtained by substituting the difference between the target value and the actual measurement value into the map. The map indicated by the broken line in FIG. 4 is obtained in advance by experiments or the like and stored in the ECU 90. When the process of S106 ends, this control ends.

  According to this control, the displacement of the valve timing of the intake and exhaust valves 5 and 6 that may occur when the compression ratio of the internal combustion engine 1 is changed is eliminated or suppressed as much as possible, thereby deteriorating emissions, fuel consumption, engine output. It is possible to suppress a decrease or the like.

  In this control, the processing from S104 to S106 mainly corresponds to the feedback gain correction means of the present invention.

  Further, in the present embodiment, the processes of step S103 and step S104 may be interchanged. Thereby, the proportional gain can be changed before the compression ratio is changed.

  In the present embodiment, the variable compression ratio internal combustion engine in which the cylinder block 3 moves relative to the crankcase 4 has been described. However, the present invention is not limited to this, and the valve timing is set to an appropriate timing in accordance with the change in the compression ratio. Any variable compression ratio internal combustion engine can be applied.

  Further, in this embodiment, the intake side VVT 23 and the exhaust side VVT 26 are provided, but the present invention can also be applied to an internal combustion engine provided with only one of them. The present invention can also be applied to an internal combustion engine having a mechanism that can arbitrarily change the valve timing by an electromagnetically driven valve or the like. Further, the present invention can be applied to an internal combustion engine provided with a variable rotation phase mechanism that can change the relative rotation phase between the crankshaft 13 and the crank pulley 32.

1 is a diagram illustrating a schematic configuration of a variable compression ratio internal combustion engine to which a valve timing control system for a variable compression ratio internal combustion engine according to a first embodiment is applied. FIG. 1 is a first diagram showing a mechanism of a valve timing control system for a variable compression ratio internal combustion engine according to Embodiment 1. FIG. FIG. 3 is a second diagram illustrating the mechanism of the valve timing control system for the variable compression ratio internal combustion engine according to the first embodiment. It is the figure which showed the relationship between the difference of the target value of valve timing which concerns on Example 1, and a measured value, and the proportional gain of duty control of valve timing. It is the figure which showed the relationship between the duty ratio at the time of the valve timing change which concerns on Example 1, and the operating speed of intake side VVT and exhaust side VVT. 6 is a time chart showing changes in the advance amounts of the intake side VVT and the exhaust side VVT at the normal time and when the compression ratio is changed according to the first embodiment. In the valve timing control system of the variable compression ratio internal combustion engine according to the first embodiment, it is a diagram showing a control flow of compression ratio change control performed when the compression ratio is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Cylinder block 4 Crankcase 5 Intake valve 6 Exhaust valve 7 Intake side cam 8 Exhaust side cam 9 Variable compression ratio mechanism 9a Shaft part 9b Cam part 9c Movable bearing part 9d Worm wheel 9e Worm 9f Motor 10 Cylinder head 13 crankshaft 14 connecting rod 15 piston 16 spark plug 17 fuel injection valve 18 intake port 19 intake pipe 20 exhaust port 21 exhaust pipe 22 intake side camshaft 24 intake side pulley 25 exhaust side camshaft 27 exhaust side pulley 28 first cylinder block side Pulley 29 Second cylinder block side pulley 30 First crankcase side pulley 31 Second crankcase side pulley 32 Crank side pulley 33 Timing belt 90 ECU
91 Crank position sensor 92 Accelerator opening sensor 93 Intake side cam angle sensor 94 Exhaust side cam angle sensor

Claims (4)

In an internal combustion engine equipped with a variable compression ratio mechanism that changes the compression ratio by changing the relative distance between the cylinder head and the piston ,
A valve timing changing device for changing the valve timing of at least one of the intake valve and the exhaust valve; and
A valve timing control device that feedback-controls the valve timing changing device so that an actual valve timing converges to a target valve timing based on an operating state of the internal combustion engine;
If the difference between the target valve timing and the actual valve timing is the same when the compression ratio is changed by the variable compression ratio mechanism and when the compression ratio is not changed, the compression ratio is changed by the variable compression ratio mechanism. Sometimes, the feedback gain correction means for setting the feedback gain in the feedback control of the valve timing changing device to a value larger than the feedback gain when the compression ratio is not changed,
An internal combustion engine provided with a variable compression ratio mechanism. The internal combustion engine having a variable compression ratio mechanism according to claim 1 , wherein the time when the compression ratio is changed by the variable compression ratio mechanism is a predetermined period from the start of the compression ratio change. The variable compression ratio mechanism further includes compression ratio change determination means for determining whether or not to change the compression ratio, and the variable compression ratio mechanism changes the compression ratio after the compression ratio change determination is made by the compression ratio change determination means, and the variable compression 2. An internal combustion engine having a variable compression ratio mechanism according to claim 1 , wherein the time when the compression ratio is changed by the ratio mechanism is a predetermined period after the determination of the compression ratio change is made. The internal combustion engine having a variable compression ratio mechanism according to claim 2 or 3 , wherein the predetermined period is a period until an actual valve timing reaches a target valve timing.

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