JP4110836B2 - Control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of an internal combustion engine that switches between compression self-ignition combustion and spark ignition combustion.
[0002]
[Prior art]
The spark ignition type engine has an advantage of a large specific output. However, since the fuel consumption is inferior due to the intake throttle loss at low load, the improvement of the fuel consumption by lean combustion with a lean air-fuel ratio is becoming common.
As lean combustion, homogeneous lean combustion that forms a homogeneous lean mixture in the combustion chamber and stratified lean that forms a flammable air-fuel mixture mixture stratified around the spark plug by directly injecting fuel into the combustion chamber There is combustion. Since the latter can further dilute the entire air-fuel ratio, the effect of improving the fuel consumption at a low load is great, but the emission of NOx, smoke, etc. tends to increase.
[0003]
In order to solve this problem, there is what is called compression self-ignition combustion, which realizes lean combustion by self-igniting homogeneous premixed gas by piston compression etc., and is focused on achieving both low fuel consumption and low emission Has been.
As a control of a conventional internal combustion engine using the compression self-ignition combustion, Japanese Patent Laid-Open No. 2000-220458 switches between spark ignition combustion and compression self-ignition combustion according to operating conditions, for example, spark ignition combustion. When switching from the self-ignition combustion to the compression self-ignition combustion, the ignition timing of the engine is gradually retarded to smoothly switch from the spark ignition combustion to the compression self-ignition combustion.
[0004]
[Problems to be solved by the invention]
However, in practice, it is not easy to achieve both spark ignition combustion and compression self-ignition combustion in one engine. For example, a low compression ratio adapted to spark ignition combustion is set to attempt compression self-ignition combustion. However, the compression end temperature is too low and misfires.
[0005]
The present invention has been made paying attention to such a conventional problem, and performs switching control to a compression end temperature suitable for compression self-ignition combustion and spark ignition combustion, and also maintains good combustibility during switching transition. It is an object of the present invention to provide a control device for an internal combustion engine in which smooth combustion switching is performed.
[0006]
[Means for Solving the Problems]
Therefore, the present invention provides a compression self-ignition type internal combustion engine that switches between spark ignition combustion and compression self-ignition combustion according to the operating state of the engine as described above. While controlling the switching of the temperature, the fuel is injected into the cylinder during the entire expansion stroke in the middle of the switching.
[0007]
The fuel injected during the expansion stroke raises the temperature of the burnt gas by combustion, and the high-temperature gas remains in the next cycle, so that the temperature of the mixture in the next cycle rises. In the next cycle, compression self-ignition combustion Is feasible.
Therefore, when switching from spark ignition combustion to compression self-ignition combustion, immediately after the start of switching of the compression end temperature control, the temperature at the expansion stroke fuel injection is used together to increase the compression end temperature, thereby switching to compression self-ignition combustion. It is possible to switch, and then the switching is smoothly completed by switching to the compression self-ignition combustion in which the expansion stroke fuel injection is not performed.
[0008]
Also, when switching from compression self-ignition combustion to spark ignition combustion, switch to compression self-ignition combustion once combined with temperature rise by expansion stroke fuel injection, stop expansion stroke fuel injection in the final cycle, and It is possible to smoothly switch to spark ignition combustion by lowering the compression end temperature.
In this way, by performing expansion stroke fuel injection in parallel with basic compression end temperature switching control in accordance with switching of combustion, knocking and misfire can be avoided at any switching time. There is an advantage that fuel is not discharged. In addition, since the expansion stroke fuel injection is performed only at the time of switching, the fuel consumption can be maintained well.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram showing the configuration of the first embodiment of the internal combustion engine according to the present invention. In FIG. 1, the internal combustion engine has a combustion chamber 4 defined by a cylinder head 1, a cylinder block 2 and a piston 3, and introduces fresh air from an intake port 7 through an intake valve 5 and an exhaust valve 6. Exhaust gas is discharged from the exhaust port 8. The fuel injection valve 9 directly injects fuel into the combustion chamber. The air-fuel mixture formed in the combustion chamber is ignited and burned by the spark plug 10. The internal combustion engine is integrally controlled by an ECU (Engine Control Unit) 11.
[0010]
Signals from the accelerator opening sensor 12, the water temperature sensor 13, the crank angle sensor 14, and the like are input to the ECU 11, and necessary processes and calculations are performed inside the ECU 11 to control the fuel injection valve 9, the spark plug 10, and the like.
The internal combustion engine in the present embodiment further has a variable compression ratio mechanism that changes the compression ratio of the engine. Various types of variable compression ratio mechanisms are known, but in this embodiment, as shown in FIG. 1, an upper link 17 connected to a lower link 16 connected to a crankshaft 15 is used. Thus, the piston 3 is moved up and down. The other end of the lower link 16 is connected to a control rod 18. By moving the control rod 18 by an actuator 19, the piston position at the top dead center is made variable, and the compression ratio is controlled. The actuator 19 is controlled by the ECU 11.
[0011]
2 and 3 show the operation of the link mechanism. FIG. 2 shows the case where the piston 3 is located closer to the cylinder head 1 at the top dead center, that is, the case where the compression ratio is high. FIG. The case where it is located away, that is, the case where the compression ratio is low is shown.
FIG. 4 shows control parameters and engine state quantities with respect to time when switching from spark ignition combustion to compression self-ignition combustion in this embodiment. In this embodiment, the compression end temperature is increased by increasing the compression ratio to realize compression self-ignition combustion. When switching from spark ignition combustion to compression self-ignition combustion, the variable compression ratio mechanism is used to change the compression ratio. (VCR). Under this transition state during switching, the compression ratio (corresponding compression end temperature) is too high for spark ignition combustion and too low for compression self-ignition combustion. Therefore, in the present embodiment, by increasing the temperature of the residual gas during this transition period, compression self-ignition combustion is realized even when the compression ratio is not sufficiently high.
[0012]
The EGR rate in FIG. 4 does not indicate the rate of gas recirculated from the exhaust pipe to the intake pipe (so-called external EGR gas), but indicates the rate of burned gas remaining in the combustion chamber until the next cycle. In the present embodiment, the residual gas ratio does not change greatly even when the combustion mode changes.
T (EGR) indicates the temperature of this residual gas. During the transition from spark ignition combustion to compression self-ignition combustion, the temperature of the residual gas is high at the start of switching, that is, when the compression ratio is low, and is controlled to be low as switching proceeds, that is, as the compression ratio increases. The That is, when the compression ratio is low, the compression end temperature decreases, but by increasing the residual gas temperature, the initial mixture temperature at the start of compression can be increased, so that the decrease in the compression end temperature can be compensated for, and compression self-ignition combustion is performed. It becomes possible. In addition to the main fuel injection (Qf1), the residual gas temperature is controlled by injecting fuel into the cylinder (Qf2) during all expansion strokes during the transition from spark ignition combustion to compression self-ignition combustion, and combusting the fuel. It is done by damaging. As the compression ratio increases, the need to increase the temperature of the residual gas becomes smaller, so Qf2 is gradually reduced and becomes zero when the compression ratio switching is completed. Compressed self-ignition combustion can be performed at a leaner air-fuel ratio than spark ignition combustion.When switching, the throttle valve of the engine is gradually opened to reduce the intake negative pressure. Furthermore, low fuel consumption can be obtained. At this time, the total air-fuel ratio becomes lean, but during the transition, there is fuel injection (Qf2) in the expansion stroke, so the air-fuel ratio temporarily shifts to the rich side.
[0013]
Conversely, when switching from compression self-ignition combustion to spark ignition combustion, the time may be considered to change from right to left in FIG. However, in this case, the compression ignition is performed in the cycle immediately after the actual value of the compression ratio reaches the target value and the fuel injection during the expansion stroke is finished (the spark ignition is not performed in the immediately following cycle).
FIG. 5 is a time chart showing fuel injection and ignition control when switching combustion modes. The upper part of the figure shows the case of switching from spark ignition combustion (SI) to compression self-ignition combustion (CI). Immediately before the switching, main fuel injection is performed during the intake stroke, and spark ignition combustion is performed as usual. In the first cycle during switching, fuel is injected during the intake stroke to cause spark ignition combustion, and fuel is injected into the cylinder during the expansion stroke. In the next cycle, the temperature of the residual gas is high due to the combustion of the fuel injected during the expansion stroke in the previous cycle, so that compression self-ignition combustion is possible. At this time, spark ignition is not performed. Further, in the subsequent cycle, in order to perform the compression self-ignition combustion by increasing the temperature of the residual gas, the fuel injection is performed in the expansion stroke also in this cycle. However, the amount decreases as the compression ratio increases. Such a cycle is continued until the switching of the compression ratio is completed, and when the switching is completed, the fuel injection amount during the expansion stroke becomes zero, whereby the switching to the steady compression self-ignition combustion is completed.
[0014]
The lower part of FIG. 5 shows the case of switching from compression self-ignition combustion to spark ignition combustion. Until the start of switching, normal compression self-ignition combustion is performed under a high compression ratio. Although compression self-ignition combustion is performed even during switching, in order to promote ignition in the next cycle, fuel injection is performed during the expansion stroke to increase the temperature of the residual gas. The amount of fuel injection during the expansion stroke is gradually increased as the compression ratio decreases. Since the high-temperature residual gas exists at the time when the switching of the compression ratio is completed, the final compression self-ignition combustion is performed. In this cycle, fuel injection in the expansion stroke is stopped, and normal spark ignition is performed from the next cycle, thereby completing the switching to steady spark ignition combustion.
[0015]
6 and 7 show a control flow in the present embodiment. First, in step S1, the ECU 11 detects an operating state such as the engine speed and load based on information from the accelerator opening sensor 12, the water temperature sensor 13, and the crank angle sensor.
Next, in step S2, the main fuel injection amount Qf1 is set with reference to a map as shown in FIG. 7 based on the load (accelerator opening degree and the like) and the engine speed. When the main fuel injection timing is also controlled according to the engine operating conditions, the fuel injection timing map may be referred to at the same time.
[0016]
In step S3, the fuel injection amount Qf2 during the expansion stroke is cleared to zero. This is because, in both spark ignition combustion and compression self-ignition combustion, fuel injection is not performed in the expansion stroke during normal control.
In step S4, the ignition timing is set by referring to the map.
In step S5, it is determined whether or not the engine is in a state of switching the combustion mode. If not switched, that is, if the current combustion mode is to be continued, the process proceeds to step S6. Based on whether the current combustion mode is spark ignition combustion or compression self-ignition combustion, in the case of compression self-ignition combustion, in step S7 Cancel the ignition setting. Thereafter, in steps S8 to S9, main fuel injection and ignition commands during the intake stroke are issued to the fuel injection device and the ignition device, respectively.
[0017]
However, when the determination in step S6 is compression self-ignition combustion, since the ignition setting is cleared, the ignition in step S9 is not actually performed.
Next, in step S10, when the fuel injection during the expansion stroke is instructed but the combustion state is not switched as described above, since Qf2 = 0, the actual injection is not performed.
[0018]
If it is determined in step S5 that the spark ignition combustion is shifted to the compression self-ignition combustion, first, in step S11, a target air-fuel ratio for compression self-ignition combustion is set.
In step S12, the current compression ratio is compared with the target compression ratio. If the current compression ratio is lower than the target compression ratio, the actuator of the variable compression ratio mechanism is driven in step S13 to switch the compression ratio. To start.
[0019]
Next, in step S14, the fuel injection amount Qf2 during the expansion stroke is determined by referring to the map, and the temperature rise control is performed. For example, as shown in the upper part of FIG. 5, Qf2 is set to be larger as the difference between the actual compression ratio and the target compression ratio is larger.
In step S15, it is determined whether it is the first cycle after the start of switching. This is because, as already shown in FIG. 5, spark ignition combustion is performed only in the first cycle after the start of switching. That is, if it is the first cycle, the ignition setting set in step S4 is maintained as it is, and if it is a subsequent cycle, the ignition setting is canceled so that the spark ignition in step S9 is not performed.
[0020]
In this way, when the compression ratio is increased and it is determined in step S12 that the target compression ratio has been reached, it is determined in step S17 that the temperature increase control has ended, and the process proceeds to step S16 to cancel the ignition setting. Return to normal control.
On the other hand, if it is determined in step S5 that the shift from compression self-ignition combustion to spark ignition combustion is determined, a target compression ratio for spark ignition combustion is set in step S18.
[0021]
In step S19, this is compared with the current compression ratio. If it is larger than the target value, the actuator of the variable compression ratio mechanism is driven in step S20 to start compression ratio reduction control.
In step S21, the fuel injection amount Qf2 during the expansion stroke is set, and the temperature rise control is performed. For example, as shown in the lower part of FIG. 5, the smaller the difference between the actual compression ratio and the target compression ratio, the larger Qf2 is set. Since compression self-ignition combustion is performed during the switching period, the ignition setting is canceled in step S22.
[0022]
In this way, when it is determined that the compression ratio has been reduced and the target compression ratio has been reached in step S19, it is determined in step S23 that the temperature rise control has ended, and the process proceeds to step S22 to cancel the ignition setting. Return to normal control.
With the above mechanism and control, in the present embodiment, knocking and combustion instability can be avoided during spark ignition combustion, and high thermal efficiency can be obtained during compression self-ignition combustion. Also, when switching between the two combustion systems, knocking and misfire can be avoided and switching can be performed smoothly.
[0023]
Next, a second embodiment will be described. Since the second embodiment has a large portion in common with the first embodiment, the description will focus on the different portions.
FIG. 9 is a system configuration diagram showing the configuration of the second embodiment. Basically similar to the configuration shown in the first embodiment (the common parts are indicated by the same reference numerals), but does not have a variable compression ratio mechanism, and as an alternative, a variable valve mechanism for each of the intake system and the exhaust system. 5b, 6b. This variable valve mechanism is one that makes at least the closing timing of the exhaust valve and the opening timing of the intake valve variable. For example, a combination of a mechanism that changes the phase of the camshaft relative to the crankshaft and a mechanism that changes the cam operating angle Can be realized. These valve timings are controlled by the ECU 11.
[0024]
FIG. 10 shows an example of setting the valve timing in each combustion mode in the present embodiment. At the time of spark ignition combustion, so-called normal valve timing is used, and the amount of residual gas is controlled to be small so as to suppress knocking and realize stable flame propagation combustion. At the time of compression self-ignition combustion, burnt gas is confined in the cylinder by advancing the closing timing of the exhaust valve, and introduced into the next cycle as a large amount of residual gas. A so-called minus overlap is performed. At this time, compression work occurs from the closing timing of the exhaust valve to the top dead center, and at the same time, by delaying the opening timing of the intake valve, this compression required the question from the top dead center to the opening timing of the intake valve. Work can be recovered.
[0025]
FIG. 11 shows each control parameter and engine state quantity with respect to time when switching from spark ignition combustion to compression self-ignition combustion in the present embodiment. In this embodiment, the valve timing is controlled to increase the amount of residual gas by increasing the amount of minus overlap (O / L), thereby increasing the average mixture temperature in the next cycle and increasing the compression end temperature. The compression self-ignition combustion is realized. When switching from the spark ignition combustion to the compression self-ignition combustion, the residual valve rate is controlled by a variable valve mechanism. Under this transition state during switching, the residual gas rate is too high for spark ignition combustion and too low for compression self-ignition combustion. Therefore, in the present embodiment, during this transition period, the temperature of the residual gas is increased, thereby realizing the compression self-ignition combustion even in a state where the amount of the residual gas is not sufficiently increased.
[0026]
Since most of the control details in this embodiment are the same as those in the first embodiment, most of the description is omitted. The difference is that, in the first embodiment, the compression ratio is controlled by the variable compression ratio mechanism, while the minus O / L amount, that is, the residual gas ratio is controlled by the variable valve timing mechanism. The control flow is also omitted here because it only replaces the portion related to the compression ratio with the minus O / L amount. With the above mechanism and control, in this embodiment as well as in the first embodiment, when switching between spark ignition combustion and compression ignition, it is possible to avoid occurrence of knocking or misfire and to perform switching smoothly.
[0027]
Next, a third embodiment will be described. Since the third embodiment has a large portion in common with the first embodiment, the description will focus on the different portions. FIG. 12 is a system configuration diagram showing the configuration of the third embodiment according to the present invention. Although it is basically similar to the configuration shown in the first embodiment (common portions are indicated by the same reference numerals), it does not have a variable compression ratio mechanism, and includes a heater 20 in the intake pipe as an alternative. Heating of the heater is controlled by the driving device 20b, and the ECU 11 gives a control command to the heater driving device 20b.
[0028]
FIG. 13 shows the control parameters and engine state quantities when switching from spark ignition combustion to compression self-ignition combustion with respect to time in the present embodiment. In the present embodiment, the compression end temperature is increased by raising the temperature of the intake air by a heater installed in the intake pipe, thereby realizing compression self-ignition combustion. When switching from spark ignition combustion to compression self-ignition combustion Is controlled to increase the intake air temperature by energizing the heater. However, since there is a delay in heating by the heater, under this transition state during switching, the intake air temperature is too high for spark ignition combustion and too low for compression self-ignition combustion. Therefore, in this embodiment, the temperature of the residual gas is increased during this transition period, so that the mixture temperature at the start of compression and the compression end temperature are increased even when the temperature of the intake air is not sufficiently high. Achieve self-igniting combustion.
[0029]
Since most of the control details in this embodiment are the same as those in the first embodiment, the description thereof is omitted for the most part. The difference is that, in the first embodiment, the intake air temperature is controlled by a heater as opposed to controlling the compression ratio by a variable compression ratio mechanism. In the control flow, the portion relating to the compression ratio may be replaced with the intake air temperature, and is omitted here. With the mechanism and control described above, in the internal combustion engine in the present embodiment, when switching between spark ignition combustion and compression ignition, it is possible to avoid the occurrence of knocking or misfire and to perform switching smoothly. In the present embodiment, a heater is used as a device for heating the intake air. However, for example, a device for heating the intake air by using the heat of exhaust gas by a heat exchanger or the like may be used. In this case, the power consumed by the heater can be saved, which contributes to the improvement of the overall efficiency of the engine.
[0030]
According to the above embodiment, in the control device for an internal combustion engine that can selectively switch between the two combustion states of compression self-ignition combustion and spark ignition combustion according to the operating state, the fuel can be directly injected into the cylinder. A fuel injection valve (fuel injection means) capable of injecting fuel in the expansion stroke, a variable compression ratio mechanism for controlling the compression end temperature according to the combustion state, a variable valve mechanism or a heater for controlling the intake air temperature (compression end temperature) Control means) and an ECU (switching time control means) for injecting fuel during the expansion stroke from the start to the end of the switching of the compression end temperature by the control of the compression end temperature control means according to the switching of the combustion state By providing
When the two combustion states of compression self-ignition combustion and spark ignition combustion are stable, the compression end temperature suitable for each combustion state is controlled by any mechanism for controlling the compression end temperature. While the combustion state is obtained and the compression end temperature is being switched according to the switching of the combustion state, the fuel injection control during the expansion stroke is used together to maintain the compression end temperature well according to the combustion state being switched. Therefore, the combustion state can be switched smoothly.
[0031]
In addition, since the amount of fuel injected during the expansion stroke is controlled according to the degree of change in the compression end temperature by the compression end temperature control, the residual gas that has been appropriately heated at any time during switching This has the advantage that the compression ignition acceleration effect is obtained and that knocking and misfire can be avoided and the discharge of unburned fuel can be avoided.
[0032]
In addition, as in the first embodiment, the compression end temperature is controlled by a variable compression ratio mechanism that controls the compression ratio of the engine, and the compression corresponding to the target value of the compression end temperature according to the switching of the combustion state. Since the fuel is injected during the expansion stroke from when the target value of the ratio is switched until the actual compression ratio reaches the target value after switching, the compression ratio is reduced during spark ignition combustion. By controlling, knocking can be suppressed and high output can be obtained, and at the time of compression self-ignition combustion, by controlling the compression ratio high, the lean mixture can be ignited steadily and high thermal efficiency can be obtained. is there.
[0033]
Further, as in the second embodiment, the compression end temperature is controlled by controlling the amount of working gas flowing into the cylinder, and the switching time control means is configured to control the compression end temperature according to the switching of the combustion state. By switching the target value of the working gas amount corresponding to the target value of the temperature until the actual working gas amount reaches the target value after switching, the fuel is injected during the expansion stroke. By controlling the residual gas amount small during spark ignition combustion, knocking can be suppressed and high output can be obtained, and during compression self-ignition combustion, the residual gas amount can be controlled largely to increase the temperature of the air-fuel mixture. The air-fuel mixture can be ignited steadily.
[0034]
Further, the variable valve operating means for increasing the amount of the working gas by controlling the amount of the working gas by delaying the opening timing of the intake valve of the engine or by closing the closing timing of the exhaust valve of the engine. Thus, the residual gas amount can be adjusted to a temperature suitable for compression self-ignition combustion.
Further, as in the third embodiment, the compression end temperature is controlled by increasing the temperature of the intake air flowing into the engine, and the intake air corresponding to the target value of the compression end temperature according to the switching of the combustion state. By adopting a configuration in which fuel is injected during the expansion stroke from when the target temperature value is switched until the actual intake air temperature reaches the target value after switching, the temperature of the intake air is controlled during spark ignition combustion. Low control suppresses knocking and increases the volumetric efficiency of the engine to obtain a high output.At the time of compression self-ignition combustion, the intake air temperature is controlled to increase the temperature of the air-fuel mixture and the lean mixture Can be ignited steadily.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram according to a first embodiment of the present invention.
FIG. 2 is a view for explaining a high compression ratio state of the variable compression ratio mechanism in the first embodiment.
FIG. 3 is a view for explaining a high compression ratio state of the variable compression ratio mechanism in the first embodiment.
FIG. 4 is a diagram showing changes in control parameters and state quantities in the first embodiment.
FIG. 5 is a time chart regarding fuel injection and ignition in the first embodiment.
FIG. 6 is a diagram showing a control flow in the first embodiment.
FIG. 7 is a diagram showing a part of the control flow.
FIG. 8 is a combustion state switching determination map used in the control flow in the first embodiment.
FIG. 9 is a system configuration diagram according to the second embodiment.
FIG. 10 is a view for explaining valve timing in the second embodiment.
FIG. 11 is a diagram showing changes in control parameters and state quantities in the second embodiment.
FIG. 12 is a system configuration diagram according to a third embodiment.
FIG. 13 is a diagram showing changes in control parameters and state quantities in the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 4 ... Combustion chamber 5a ... Variable valve mechanism of intake valve 6b ... Variable valve mechanism of exhaust valve 9 ... Fuel injection valve 10 ... Spark plug 11 ... ECU (encin control unit) 12 ... Accelerator opening sensor 13 ... Water temperature sensor 14 ... Crank angle sensor 16 ... Lower link 17 ... Upper link 18Control rod 19 ... Actuator 20 ... Heater 20b ... Heater drive device

Claims (6)

In a control device for an internal combustion engine capable of selectively switching between two combustion states of compression self-ignition combustion and spark ignition combustion according to an operating state,
Fuel injection means capable of directly injecting fuel into the cylinder and injecting fuel in an expansion stroke;
Compression end temperature control means for controlling the compression end temperature according to the combustion state;
Between the switching start of the compression end temperature to the switching completion by the control of the compression end temperature control means in accordance with switching of the combustion state, and the switching control means for injecting fuel into all of the expansion stroke,
A control device for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the switching time control means controls the amount of fuel injected during the expansion stroke in accordance with the degree of change in the compression end temperature by the compression end temperature control means. . The compression end temperature control means is constituted by compression ratio control means for controlling the compression end temperature by controlling the compression ratio of the engine,
The switching-time control means is configured to change the actual compression ratio until the target value after the switching is reached after the target value of the compression ratio corresponding to the target value of the compression end temperature is switched according to the switching of the combustion state. 3. The control apparatus for an internal combustion engine according to claim 1, wherein fuel is injected during the expansion stroke. The compression end temperature control means is constituted by working gas amount control means for controlling the compression end temperature by controlling the amount of working gas flowing into the cylinder,
The switching-time control means reaches the target value after switching after the target value of the working gas amount corresponding to the target value of the compression end temperature is switched according to the switching of the combustion state. 3. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel is injected during the expansion stroke.   The working gas amount control means is constituted by variable valve operating means for increasing the working gas amount by delaying the opening timing of the intake valve of the engine or at least one of closing the closing timing of the exhaust valve of the engine. The control device for an internal combustion engine according to claim 4, wherein the control device is an internal combustion engine. The compression end temperature control means is composed of intake air temperature control means for controlling the compression end temperature by increasing the temperature of the intake air flowing into the engine,
The switching time control means is a period from when the target value of the intake air temperature corresponding to the target value of the compression end temperature is switched according to switching of the combustion state until the actual intake air temperature reaches the target value after switching. 3. The control apparatus for an internal combustion engine according to claim 1, wherein fuel is injected during the expansion stroke.

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