JP5434243B2 - Variable compression ratio internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine capable of changing an engine compression ratio.

  Conventionally, an internal combustion engine having a mechanism capable of changing the engine compression ratio (hereinafter referred to as a variable compression ratio internal combustion engine) has been proposed. If the compression ratio is set high during engine operation, power can be obtained efficiently, but there is a problem that knocking is likely to occur. For this reason, in the variable compression ratio type internal combustion engine, the compression ratio is changed according to the operating state. Specifically, when the load on the internal combustion engine is low, knocking is unlikely to occur, so the compression ratio is set high. On the other hand, when the load on the internal combustion engine is high, knocking is likely to occur, so the compression ratio is set low.

  However, for example, when the driver suddenly opens the accelerator, that is, when the accelerator opening is changed from a small state to a large state, the load of the internal combustion engine increases, so the target compression ratio is changed from a large value to a small value. Although a change request is issued, in practice, the compression ratio may not be lowered quickly due to the mechanism of the variable compression ratio.

  Focusing on this point, conventionally, in order to further suppress abnormal combustion such as knocking that may occur during a change period from a high compression ratio to a low compression ratio, an invention as shown in Patent Document 1 below is known. Yes. According to this invention, when the mechanical compression ratio changing unit is controlled to change from the first state having a relatively high mechanical compression ratio to the second state having a relatively low state, the closing timing of the intake valve is changed. Thus, the effective compression ratio is changed to be smaller than the effective compression ratio in the second state, or the operating angle of the intake valve is changed to be set smaller than the operating angle in the second state. Thus, the effective compression ratio in the change period is set lower than the effective compression ratio in the second state.

JP 2004-239174 A

  However, in the invention shown in Patent Document 1, in order to reduce the effective compression ratio, the closing timing of the intake valve is delayed or the operating angle is reduced, but when the closing timing is delayed, When the engine speed is relatively low, the blowback of the intake air occurs, resulting in a decrease in output due to a decrease in volumetric efficiency. On the other hand, when the operating angle is reduced, there is an inertia effect of intake air. To obtain the same level of output, the effective compression ratio reduction effect is reduced. Since the amount is small, there is a problem that the output is reduced. That is, while considering the prevention of knocking, the question of how to reduce the effective compression ratio according to the driving situation has not been answered.

  Therefore, the present invention achieves a transient load characteristic required by the driver and suppresses the occurrence of knocking, that is, makes a determination based on the load characteristic required by the driver, and preferable effective compression ratio changing means. The purpose is to provide.

In order to achieve the above object, the variable compression ratio internal combustion engine of the present invention includes a mechanism capable of changing the engine compression ratio and a mechanism capable of changing the closing timing of the intake valve. Then, the degree of acceleration is compared with a first predetermined value and a second predetermined value smaller than the first predetermined value. The second predetermined value corresponds to the degree of acceleration at which the actual change in the mechanical compression ratio can follow the change in the mechanical compression ratio required with acceleration, and the degree of acceleration is greater than the second predetermined value. If it is larger, it is determined that it is necessary to delay the closing timing of the intake valve so as to move away from the vicinity of the bottom dead center in order to reduce the effective compression ratio . degree sets the closing timing of the intake valve when Kere magnitude than the first predetermined value to the retard side from the bottom dead center, than the bottom dead center of the closing timing of the first intake valve is equal to or less than a predetermined value It is characterized by being set on the advance side .

  According to the present invention, the occurrence of knocking can be suppressed while realizing the transient load characteristics required by the driver.

1 is an overall schematic diagram of a variable compression ratio internal combustion engine according to a first embodiment. The structure explanatory view of the variable valve mechanism in the present invention. Sectional drawing of the principal part of a lift and a working angle variable mechanism. The characteristic view which shows the characteristic change of the lift and working angle by a lift and working angle variable mechanism. The characteristic view which shows the phase change of the valve lift characteristic by a phase variable mechanism. The characteristic view which shows an intake valve lift characteristic. The control system whole figure of this invention. An example of the engine compression ratio map of this invention. The relationship of each index due to the difference in the closing timing of the intake valve when the amount of intake air is equal Time chart during slow acceleration Time chart for sudden acceleration (relatively rapid) of this control. Time chart during sudden acceleration (medium) of this control. 3 is a flowchart of control in the first embodiment. FIG. 3 is a schematic configuration diagram of Embodiment 2. 10 is a flowchart of control in the second embodiment. 10 is a flowchart of control in Embodiment 3.

  Hereinafter, preferred embodiments for realizing a variable compression ratio internal combustion engine of the present invention will be described based on Examples 1 to 3 shown in the drawings.

  FIG. 1 is an overall view showing an overall schematic configuration of a variable compression ratio internal combustion engine according to a first embodiment. The engine according to the embodiment has a mechanism capable of changing a mechanical compression ratio and a variable valve mechanism for an intake valve in addition to a conventionally known internal combustion engine. Here, the mechanical compression ratio means a value obtained by dividing the sum of the volume of the combustion chamber and the piston stroke volume when the piston 4 is at the bottom dead center by the volume of the combustion chamber when the piston 4 is at the top dead center. .

  As shown in FIG. 1, the internal combustion engine body includes a cylinder head 2 and a cylinder block 3, and a piston 4 that reciprocates up and down is provided in the cylinder. As a result, the combustion chamber 1 is formed. The cylinder head 2 is provided with an intake port 5 that guides intake air to the combustion chamber 1 and an exhaust port 6 that sends burned exhaust gas to the exhaust pipe. An intake valve 7 is disposed in the intake port 5 and an exhaust valve 8 is disposed in the exhaust port 6. An intake valve swing cam 58 and an exhaust valve cam 10 for operating them are substantially omitted. Located at the top. Further, a fuel injection valve 11 and a spark plug 12 are disposed between the intake valve 7 and the exhaust valve 8. An engine control unit 13 for electrically controlling the internal combustion engine and an ignition coil 14 for increasing the voltage are controlled in the vicinity of or away from the internal combustion engine, and the intake air amount is controlled upstream of the intake port 5. A throttle valve 15 is provided.

  On the other hand, the mechanism capable of changing the mechanical compression ratio includes an upper link 20 having one end connected to the piston 4 of each cylinder via a piston pin 26, and swinging to the other end of the upper link 20 via an upper link pin 27. The lower link 21 is connected to a crank pin (not shown) of the crankshaft 25, the control shaft 23 extends substantially parallel to the crankshaft 25, and one end is swingably connected to the control shaft 23. And a control link 22 having the other end pivotably connected to the lower link 21 via a control link pin 28. Here, the central axis of the control shaft 23 and the central axis of the fastening portion of the control link 22 are eccentric to each other. When the control shaft 23 rotates, the fastening portion with the control link 22 moves, and the lower link 21 By changing the inclination, the top dead center positions of the upper link 21 and the piston 4 are changed. The control shaft 23 is rotated by a mechanical compression ratio changing actuator 24 with a motor. Thus, the mechanical compression ratio can be made variable by changing the piston top dead center position.

  FIG. 2 shows the variable valve mechanism of this embodiment. This mechanism is installed above the swing cam 58 for the intake valve. This variable valve mechanism is a variable phase that advances or retards the lift / operating angle variable mechanism 50 that changes the lift amount and operating angle of the intake valve 7 and the phase of the lift center angle (phase relative to the crankshaft 25). The mechanism 70 is combined.

  FIG. 3 is a schematic view of the lift / operating angle variable mechanism. The mechanism of each representative part will be described later. The variable lift / operating angle mechanism 50 has a hollow shape rotatably supported by an intake valve 7 slidably provided on a cylinder head 2 via a valve guide (not shown) and a cam bracket 51 above the cylinder head 2. Drive shaft 52 and an eccentric cam 53 fixed to the drive shaft 52 by press-fitting or the like. A control shaft 54 that is rotatably supported by the same cam bracket 51 at a position above the drive shaft 52 and that is disposed in parallel with the drive shaft 52 and is supported by the eccentric cam portion 55 of the control shaft 54 so as to be swingable. The rocker arm 56 and a swing cam 58 that contacts the valve lifter 57 disposed at the upper end of each intake valve 7 are provided. The eccentric cam 53 and the rocker arm 56 are linked by a link arm 59, and the rocker arm 56 and the swing cam 58 are linked by a link member 60.

  The drive shaft 52 is driven by the crankshaft 25 of the engine via a timing chain or timing belt (not shown).

  The eccentric cam 53 has a circular outer peripheral surface, the center of the outer peripheral surface is offset from the shaft center of the drive shaft 52 by a predetermined amount, and the annular portion 59a of the link arm 59 is rotatable on the outer peripheral surface. It is mated.

  The rocker arm 56 is supported at its substantially central portion by an eccentric cam portion 55, and an extension portion 59 b of the link arm 59 is linked to one end portion thereof, and an upper end portion of the link member 60 is linked to the other end portion thereof. doing. The eccentric cam portion 55 is eccentric from the axis of the control shaft 54, and accordingly, the rocking center of the rocker arm 56 changes according to the angular position of the control shaft 54.

  The swing cam 58 is rotatably supported by being fitted to the outer periphery of the drive shaft 52, and the lower end portion of the link member 60 is linked to the end portion 58a extending to the side. On the lower surface of the swing cam 58, there are a base circle surface 61a that forms a concentric arc with the drive shaft 52, and a cam surface 61b that extends in a predetermined curve from the base circle surface 61a to the end portion 58a. The base circle surface 61 a and the cam surface 61 b are formed so as to come into contact with the upper surface of the valve lifter 57 in accordance with the swing position of the swing cam 58.

  That is, the base circle surface 61a is a section in which the lift amount becomes 0 as a base circle section. When the swing cam 58 swings and the cam surface 61b contacts the valve lifter 57, the base circle section 61a gradually lifts. . A slight ramp section is provided between the base circle section and the lift section.

  As shown in FIG. 2, the control shaft 54 is configured to rotate within a predetermined rotation angle range by a lift / operation angle control hydraulic actuator 30 provided at one end. The hydraulic pressure supply to the actuator 30 is controlled by the first hydraulic pressure control unit 32 in FIG. 7 based on a control signal from the engine control unit 13. The lift / operating angle control hydraulic actuator 30 is configured to urge the intake valve 7 to the small lift / small operating angle side when the drive hydraulic pressure of the lift / operating angle control hydraulic actuator 30 is OFF. ing.

  With the above configuration, the intake valve opening / closing timing and the valve lift amount can be controlled by operating the lift / operating angle control hydraulic actuator 30. The valve lift characteristic changes continuously as shown in FIG. That is, the lift and the operating angle can be continuously expanded and contracted simultaneously. In particular, in the case shown in FIG. 4, the closing timing and opening timing of the intake valve 7 change substantially symmetrically as the lift and operating angle change.

  Next, as shown in FIG. 2, the phase variable mechanism 70 relatively rotates the sprocket 71 provided at the front end portion of the drive shaft 52 and the sprocket 71 and the drive shaft 52 within a predetermined angle range. And a hydraulic actuator 31 for phase control. The sprocket 71 is linked to the crankshaft 25 via a timing chain or a timing belt (not shown). The hydraulic pressure supply to the phase control hydraulic actuator 31 is controlled by the second hydraulic pressure control unit 33 in FIG. 7 based on a control signal from the engine control unit 13.

  With the above configuration, the hydraulic control to the phase control hydraulic actuator 31 causes the sprocket 71 and the drive shaft 52 to rotate relatively, and the lift center angle is retarded as shown in FIG. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The phase variable mechanism 70 is not limited to a hydraulic one, and various configurations such as one using an electromagnetic actuator are possible.

  By operating the variable valve mechanism including the lift / operating angle variable mechanism 50 and the phase variable mechanism 70, the intake valve lift characteristic shown in FIG. 6 can be realized, and the effective compression ratio can be changed by changing the intake valve closing timing. Here, the effective compression ratio refers to the ratio between the volume of the combustion chamber when the intake valve is closed and the minimum volume of the combustion chamber.

  By the way, the response time of the hydraulic actuator 31 for phase control for controlling the timing of the intake valve 7 and the hydraulic actuator 30 for lift / operation angle control for controlling the lift amount and operating angle of the intake valve 7 is mechanical compression. It is known that the response time of the mechanical compression ratio changing actuator 24 for controlling the ratio is earlier than the response time. Here, “the response time is fast” means that the time from when the actuator starts operating until the target value is reached after the drive command signal flows to each actuator is short. That is, the time until the target value is reached is slower in the mechanical compression ratio variable mechanism than in the phase variable mechanism 70 and the lift / operating angle variable mechanism 50. This is because the mechanical compression ratio variable mechanism has a large actuator load due to a combustion load generated during combustion of the engine.

  FIG. 7 is an explanatory diagram showing the overall configuration of the combustion control system of this embodiment, and is a combination of the above-described variable compression ratio mechanism of FIG. 1 and the variable valve mechanism of FIG.

  In the present embodiment, the crank angle sensor 40 is used to indicate the rotational speed of the internal combustion engine, the throttle valve opening sensor 41 is used to determine the throttle opening, the accelerator pedal opening sensor 42 is used to determine the accelerator pedal opening, and the intake air amount sensor. The intake air amount is detected by 43 and the knocking of the internal combustion engine is detected by the knock sensor 46, and is input to the engine control unit 13.

  The command signal from the engine control unit 13 drives the compression ratio changing actuator 24 which is a power source of the control shaft 23 of the compression ratio variable mechanism, and operates the ignition advance controller 47 for adjusting the ignition timing.

  Here, FIG. 8 shows an example of the engine compression ratio map of the present embodiment. With the variable compression ratio mechanism, the compression ratio can be changed according to operating conditions (engine rotation × engine load). For example, when the driver requests rapid acceleration from the low load condition (1) in FIG. 8, the load is increased to the high load condition (2). According to the engine load, the engine compression ratio is set to 18 under the low load condition (1), but the engine compression ratio is reduced to 10 under the high load condition (2). As described above, when the driver's acceleration request is steep, it is necessary to instantaneously reduce the compression ratio. However, since the response speed of the mechanical compression ratio changing actuator 24 is slow, the required value cannot be satisfied. As a result, the worst knocking occurs when no measures are taken.

  Conventionally, as a means for avoiding knocking under the above-described circumstances, the control for intentionally advancing or retarding the closing timing of the intake valve from near the bottom dead center is known at the beginning. As shown in the background art. This has an effect of reducing the effective compression ratio as compared with the case where the closing timing of the intake valve is not usually delayed, which is effective in avoiding knocking.

  However, changing the closing timing of the intake valve often causes drivability, blowback to intake air, and rebound of fuel consumption and the like. Here, FIG. 9 shows the relationship of each index depending on the difference in the closing timing of the intake valve when the amount of intake air is equal. The reason why the intake valve is not symmetric with respect to the bottom dead center in the case where the closing timing of the intake valve is set before and after the bottom dead center is due to the influence of the inertia effect of the intake air. In the diagram on the right side of FIG. 9, if the intake valve closing timing is changed before the bottom dead center, the intake valve closing timing change after securing the necessary intake air amount is effective compression. There is a disadvantage that the effect of reducing the ratio is small. On the other hand, in order to obtain more effective compression ratio reduction effect, it is necessary to further advance the closing timing of the intake valve, and there is a possibility that the intake air amount is insufficient, the output is insufficient, and the drivability is deteriorated. On the other hand, in the left diagram of FIG. 9, if the closing timing of the intake valve is changed after the bottom dead center, a problem such as a return to the intake air may occur, or a lift / operating angle changing mechanism may be used. In such a case, although the effect of reducing the effective compression ratio is large, it is necessary to increase the lift amount of the intake valve, leading to an increase in friction of the valve operating system, which may cause a deterioration in fuel consumption.

  Therefore, the present invention has a trade-off relationship between rebound such as blowback and friction when the effective compression ratio is delayed so that the closing timing of the intake valve is moved away from the vicinity of the bottom dead center to avoid knocking. Thus, it is determined and executed whether the closing timing of the intake valve is advanced or retarded with respect to the bottom dead center between when knocking must be avoided and when it is not. That is, an object of the present invention is to perform control to ensure output and fuel consumption while preferably avoiding knocking.

  FIG. 10 shows a time chart during slow acceleration. This is a time chart in a slow acceleration state where there is an acceleration request from the driver but the change in the mechanical compression ratio can sufficiently catch up with the acceleration. That is, the throttle valve opening speed ΔTPO (or the accelerator opening change speed ΔAPO, the intake air amount change speed ΔQA, the fuel injection amount change speed ΔTP, the target compression ratio change speed Δε, or the engine load response speed ΔTR). , Smaller than the second predetermined value TPO2 (or APO2, or QA2, or TP2, or ε2, or TR2). The throttle valve is opened by the accelerator pedal operation from the driver, and an increase in engine load is required. The transient load response from the low load condition (1) to the high load condition (2) in FIG. 8 is a requirement. The engine target compression ratio is changed from 18 in the low load condition (1) to 10 in the high load condition (2) according to the load request. With such a moderate acceleration, since the actual engine compression ratio can follow the change in the engine target compression ratio, the intake valve closing timing change control is not performed.

  FIG. 11 shows a time chart at the time of sudden acceleration (relatively rapid) in this control. The throttle valve is opened by the accelerator pedal operation from the driver, and an increase in engine load is required. That is, the transient load response from the low load condition (1) to the high load condition (2) in FIG. The engine target compression ratio is changed from 18 in the low load condition (1) to 10 in the high load condition (2) according to the load request. However, since the response speed of the mechanical compression ratio changing actuator 24 is slow, it takes time until the actual compression ratio is changed to 10. The throttle valve opening speed ΔTPO (or accelerator opening change speed ΔAPO, intake air amount change speed ΔQA, fuel injection amount change speed ΔTP, target compression ratio change speed Δε, or engine load response speed ΔTR) When it is determined that the value is greater than two predetermined values TPO2 (or APO2, or QA2, or TP2, or ε2, or TR2), the effective compression ratio changing control by changing the intake valve closing timing is entered. Then, ΔTPO (or ΔAPO, or ΔQA, ΔTP, or Δε, or ΔTR) is determined to be larger than the first predetermined value TPO1 (or APO1, QA1, or TP1, or ε1, or TR1). Then, the intake valve closing timing is set later, that is, changed to the retard side, and the effective compression ratio is lowered. Thereby, knocking of the internal combustion engine can be preferably avoided. Here, the second predetermined value is a value smaller than the first predetermined value. The ignition timing set at this time is set to the advance side as compared with the intake valve close timing change control which sets the close timing of the intake valve, which will be described later, to the advance side. By advancing the ignition timing, the combustion state can be made suitable, so that the engine load can be increased and the load response required by the driver can be realized.

  FIG. 12 shows a time chart at the time of sudden acceleration (medium) in this control. The control up to the effective compression ratio changing control by changing the intake valve closing timing is the same as the control shown in FIG. When it is determined that the first predetermined value TPO1 (or APO1, or QA1, or TP1, or ε1, or TR1) is less than or equal to, the closing timing of the intake valve is set in advance, that is, the effective compression is changed to the advance side. Reduce the ratio. Thereby, it is possible to suppress the deterioration of fuel consumption while avoiding knocking by lowering the effective compression ratio.

  FIG. 13 shows a flowchart of this control.

  In step 100 (hereinafter, referred to as S100 in the flowchart), ΔTPO, which is a change speed (or amount) of the throttle valve opening, in response to a driver's acceleration request (for example, depression of an accelerator pedal) is a second predetermined value. If it is greater than TPO2, control proceeds to step 101. In this determination, the driver's acceleration request detecting means may be the accelerator opening, the intake air amount, the fuel injection amount, or the engine load, but the target compression ratio is a means for directly solving this problem. Because it is better.

  In step 101, the intake valve closing timing change control is performed based on the determination in step 100.

  In step 102, it is further determined whether the acceleration request requested by the driver is rapid. That is, when it is larger than the first predetermined value TPO1, the process proceeds to step 103, and when it is equal to or smaller than the first predetermined value, the process proceeds to step 104.

  In step 103, in order to give priority to avoiding knocking while responding to the driver's sudden acceleration request, effective compression is performed by delaying the closing timing of the intake valve with respect to the normal time near the bottom dead center. Reduce the ratio. As the intake valve closing timing is retarded, in step 105, the ignition timing is advanced to make the combustion state suitable. As a result, the engine load can be increased, and the load response required by the driver can be realized.

  In step 104, if the driver requested sudden acceleration, but the acceleration was relatively moderate, the intake valve closing timing should be near the bottom dead center. The effective compression ratio is lowered by moving forward (advancing) with respect to the normal time. In step 106, as the intake valve closing timing is advanced, the ignition timing is advanced to make the combustion state suitable. When the intake valve closing timing is advanced, the effective compression ratio is relatively large compared to when the intake valve closing timing is retarded, and therefore the ignition timing advance amount is small.

  In Step 107 and Step 108, when the actual mechanical compression ratio approaches the target compression ratio and reaches a level that does not exceed the knocking limit, it is determined that the control for changing the mechanical compression ratio is completed. That is, when the value of the difference between the actual mechanical compression ratio and the target mechanical compression ratio (described as ε (actual-target) in FIG. 13) becomes smaller than the predetermined value α for determining the knocking limit, the valve closing timing change control is performed. Exit. Here, when the value is equal to or greater than the predetermined value α, the process returns to step 103 and step 104, respectively.

  As described above, by having a means for judging the degree of acceleration demand of the driver and a means for selecting a preferable compression ratio change, the occurrence of knocking can be prevented according to the situation or the blow-back of the intake air can be suppressed. It becomes possible.

  FIG. 14 is an overall schematic diagram of the second embodiment, which includes a turbocharger supercharger 16 and a collector intake pressure sensor 17 installed in an intake collector (not shown) in addition to the configuration of the first embodiment.

  In an internal combustion engine having a turbocharger such as a turbocharger, it is known that the knocking limit value is low because the intake air temperature is higher especially in the supercharging region compared to an internal combustion engine without a supercharger. The situation is the same for the compression ratio internal combustion engine. Therefore, it is necessary to make the control more excellent in knocking resistance than the control described in the first embodiment.

  FIG. 15 shows a flowchart of the second embodiment.

  In Step 200, the collector internal pressure is detected by the intake pressure sensor 17, and when the internal combustion engine is in the supercharging region, that is, when the collector internal pressure is larger than the atmospheric pressure, the process proceeds to Step 201. Do the same control.

  In step 201, it is determined whether or not the acceleration request requested by the driver is greater than or equal to a second predetermined value. As in the case of the first embodiment, when ΔTPO which is the change speed (or amount) of the throttle valve opening is equal to or greater than the second predetermined value, the process proceeds to step 202 and step 203.

  In step 203, the effective compression ratio is lowered by delaying the closing timing of the intake valve. In step 204, the ignition timing is advanced as in the first embodiment. In step 205, when the actual mechanical compression ratio approaches the target compression ratio and reaches a level that does not exceed the knocking limit, it is determined that the control for changing the mechanical compression ratio is finished, and the valve closing timing change control is finished. To do.

  As described above, in the internal combustion engine with a supercharger, occurrence of knocking can be reliably prevented by performing the above control in the supercharging region.

  In addition, in Example 2, although the turbocharger supercharger was raised as an example of a supercharger, a supercharger supercharger may be used.

  Although the configuration of the third embodiment is not illustrated, the configuration of the first or second embodiment includes an outside air temperature sensor that can measure the outside air temperature and a water temperature sensor that can measure the engine cooling water temperature. If the outside air temperature is high, the intake air intake temperature becomes high, so that the knocking limit value becomes low. As is well known, when the cooling water temperature is high, the temperature in the combustion chamber increases, so that the knocking limit value tends to decrease.

  FIG. 16 shows a flowchart of the third embodiment. In step 300, it is determined whether or not the outside air temperature TA is high. If the outside air temperature TA is higher than the predetermined outside air temperature TA1, the process proceeds to step 302. The case where the outside air temperature is high is, for example, a case where the outside air temperature is 35 ° C. or higher.

  On the other hand, if the outside air temperature is not high, it is determined in step 301 whether or not the cooling water temperature TW is high. If it is higher than the predetermined cooling water temperature TW1, step 302 is entered. The case where the cooling water temperature is high is, for example, the case where the cooling water temperature is 105 ° C. or higher. If the cooling water temperature is not high in step 301, the process enters step 307, and the subsequent steps are the same as in the first embodiment.

  In step 302, it is determined whether or not to change the closing timing of the intake valve based on the change rate (or amount) of the throttle valve opening similar to that shown in the first and second embodiments. is there. When it is larger than the second predetermined value TPO2, the routine proceeds to step 303, where the intake valve closing timing change control is started.

  In step 304, the effective compression ratio is lowered by delaying the closing timing of the intake valve based on the above determination. In step 305, the ignition timing is advanced as in the first and second embodiments. In step 306, when the actual mechanical compression ratio approaches the target compression ratio and reaches a level that does not exceed the knocking limit, it is determined that the control for changing the mechanical compression ratio is finished, and the valve closing timing change control is finished. To do.

  As described above, the occurrence of knocking can be reliably prevented by performing the above control under the high temperature outside air temperature condition and the high water temperature condition.

  In the above-described embodiment, the phase variable mechanism and the lift / operating angle changing mechanism are used together, but the closing timing of the intake valve is changed from near the bottom dead center by the phase variable mechanism alone or the lift / operating angle changing mechanism alone. You may control to make it delay.

DESCRIPTION OF SYMBOLS 1 Combustion chamber 4 Piston 5 Intake port 7 Intake valve 12 Spark plug 13 Engine control unit 14 Ignition coil 15 Throttle valve 16 Turbocharger supercharger 17 Collector internal pressure sensor 18 Collector 24 Mechanical compression ratio change actuator 30 For lift / working angle control Hydraulic actuator 31 Phase control hydraulic actuator 32 First hydraulic control unit 33 Second hydraulic control unit 41 Throttle valve opening sensor 42 Accelerator pedal opening sensor 43 Intake air amount sensor 44 Outside air temperature sensor 45 Water temperature sensor 50 Lift / operating angle variable Mechanism 70 Phase variable mechanism

Claims (13)

In a variable compression ratio internal combustion engine comprising means capable of changing the mechanical compression ratio and having a valve closing timing variable mechanism capable of advancing or retarding the closing timing of the intake valve ,
When there is an acceleration request, the degree of acceleration is compared with a first predetermined value and a second predetermined value smaller than the first predetermined value,
The second predetermined value corresponds to the degree of acceleration at which the actual change in the mechanical compression ratio can follow the change in the mechanical compression ratio required with acceleration, and the degree of acceleration is greater than the second predetermined value. If it is larger, it is determined that it is necessary to delay the closing timing of the intake valve to reduce the effective compression ratio and away from the vicinity of the bottom dead center ,
When it is determined that there is a need for the further, the degree of acceleration sets the closing timing of the first intake valve if Kere magnitude than a predetermined value on the retard side from the bottom dead center, the first predetermined value A variable compression ratio internal combustion engine characterized in that the closing timing of the intake valve is set to an advance side with respect to the bottom dead center if below. The variable compression ratio internal combustion engine according to claim 1 , wherein the acceleration request is determined based on an increase in an accelerator pedal opening. The variable compression ratio internal combustion engine according to claim 1 , wherein the acceleration request is determined based on an increase in throttle valve opening. 2. The variable compression ratio internal combustion engine according to claim 1 , wherein the acceleration request is determined based on an increase in intake air amount. The variable compression ratio internal combustion engine according to claim 1 , wherein the acceleration request is determined based on an increase in fuel injection amount. The variable compression ratio internal combustion engine according to claim 1 , wherein the acceleration request is determined based on a decrease in mechanical compression ratio. A variable compression ratio internal combustion engine having a supercharger, wherein when the operating region is in the supercharging region and the degree of acceleration is greater than the second predetermined value, the degree of acceleration is the first predetermined value The variable compression ratio internal combustion engine according to any one of claims 1 to 6, wherein the closing timing of the intake valve is set to be retarded from the bottom dead center regardless of whether or not it is larger . When the outside air temperature is higher than a predetermined value, if the degree of acceleration is greater than the second predetermined value , the closing timing of the intake valve will be lowered regardless of whether the degree of acceleration is greater than the first predetermined value. The variable compression ratio internal combustion engine according to any one of claims 1 to 7, wherein the variable compression ratio internal combustion engine is set at a retard angle side with respect to the point. If the degree of acceleration is greater than the second predetermined value when the coolant temperature is higher than the predetermined value , the closing timing of the intake valve is decreased regardless of whether the degree of acceleration is greater than the first predetermined value. The variable compression ratio internal combustion engine according to any one of claims 1 to 8, wherein the variable compression ratio internal combustion engine is set on the retard side with respect to the dead center. When the intake valve closing timing is set to the retarded side from the bottom dead center, the intake valve lift amount is large, and when the intake valve closing timing is set to the advanced angle side from the bottom dead center, the intake valve The variable compression ratio internal combustion engine according to any one of claims 1 to 9, wherein the lift amount of the engine is small. Compared to the response time required for the mechanical compression ratio changes by the variable compression ratio mechanism, in any one of claims 1 to 1 0, characterized in that the fast response time required for effective compression ratio changes by the closing timing varying mechanism The variable compression ratio type internal combustion engine as described. When the closing timing of the intake valve is set to the retard side from the bottom dead center, the set ignition timing is set in comparison with the case where the closing timing of the intake valve is set to the advance side from the engine bottom dead center. The variable compression ratio internal combustion engine according to any one of claims 1 to 11, wherein the internal combustion engine is advanced. When it is determined that the control for changing the mechanical compression ratio has ended, the control for delaying the closing timing of the intake valve in the direction away from the vicinity of the bottom dead center is ended in order to reduce the effective compression ratio. The variable compression ratio internal combustion engine according to any one of claims 1 to 12 .