JP2011202590A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, improving merchantability by ensuring a stable combustion state even if a combustion mode is changed over from an SI combustion mode to an HCCI combustion mode.SOLUTION: This control device for the engine 3 operable by changing over the combustion mode to the HCCI combustion mode and SI combustion mode includes an ECU 2. The ECU 2 controls exhaust valve timing to SI timing in the SI combustion mode and to the HCCI timing in the HCCI combustion mode (Steps 31-35), determines whether or not the exhaust valve timing is actually changed over to the HCCI timing after the combustion mode is changed over to the HCCI combustion mode (Step 36), and decreasingly corrects the first amount of fuel injected GFOUTP during a period until predetermined time elapses from a changeover point with the exhaust valve timing actually changed over to the HCCI timing (Steps 63, 64, 68).

Description

  The present invention relates to a control device for an internal combustion engine that can be operated by switching a combustion mode between an HCCI combustion mode in which an air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition.

  Conventionally, what was described in patent document 1 as a control apparatus of an internal combustion engine is known. This internal combustion engine can be operated by switching the combustion mode between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition. Is provided with a variable cam phase mechanism that freely changes the relative phase (hereinafter referred to as “cam phase”) with respect to the crankshaft.

  In this control device, fuel injection is performed so that one of the HCCI combustion mode and the SI combustion mode is selected as the combustion mode in accordance with the operating state of the internal combustion engine, and the actual combustion mode of the internal combustion engine becomes the selected combustion mode. When the control mode is executed and the combustion mode switching condition is satisfied (specifically, when the operating state of the internal combustion engine changes, the selected combustion mode before and after the change is different) Then, the combustion mode switching control is executed.

  In addition, the target cam phase that is the target of the cam phase is set by map search according to the operating state of the internal combustion engine, and the actual cam phase is controlled to become this target cam phase. When the switching control execution condition is satisfied (specifically, when the target cam phase changes), the cam phase switching control is executed.

  When the execution condition for the combustion mode switching control and the execution condition for the cam phase switching control are satisfied at the same timing, the combustion mode switching control is executed until the cam phase switching control is completed. Instead, the combustion mode is maintained at the previous combustion mode, and the combustion mode switching control is started when the cam phase switching control is completed.

Japanese Patent No. 3657749

  Generally, in the case of an internal combustion engine that can be operated by switching between the HCCI combustion mode and the SI combustion mode, the combustion gas temperature is higher in the SI combustion mode than in the HCCI combustion mode. Therefore, when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, the temperature in the combustion chamber becomes higher than the temperature suitable for compression-ignition combustion of the air-fuel mixture, and the self-ignition timing of the air-fuel mixture is the optimum timing. In that case, the combustion state becomes unstable, resulting in increased torque fluctuations or knocking. On the other hand, according to the above-described conventional control device for an internal combustion engine, the combustion mode switching control is only started when the cam phase switching control is completed. When switching from HCCI combustion mode to HCCI combustion mode, the above-mentioned problems occur, leading to a decline in merchantability.

  The present invention has been made to solve the above-described problems. Even when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, a stable combustion state can be ensured, thereby improving the merchantability. An object of the present invention is to provide a control device for an internal combustion engine that can be improved.

  In order to achieve the above object, the invention according to claim 1 switches the combustion mode between the HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and the SI combustion mode in which the air-fuel mixture is combusted by spark ignition. The exhaust valve timing, which is the valve timing of the exhaust valve 5, is changed by the exhaust valve timing changing device (exhaust VT switching mechanism 7), and the first fuel supply device (first In the internal combustion engine 3 in which the fuel is supplied into the combustion chamber 3d in the intake stroke by the one fuel injection valve 11), the exhaust valve timing is controlled via the exhaust valve timing changing device, and the first fuel supply device is used. A control device 1 for an internal combustion engine 3 that controls the amount and timing of fuel supplied by the first fuel supply device, A first fuel supply amount calculating means (ECU2, step 68) for calculating a first fuel supply amount (first fuel injection amount GFOUTP) as a fuel supply amount by one fuel supply device (first fuel injection valve 11), combustion As a mode, the combustion mode selection means (ECU 2, steps 12 and 13) for selecting one of the SI combustion mode and the HCCI combustion mode, and the exhaust gas timing based on the selection result of the combustion mode selection means, the SI combustion mode is selected. When the HCCI combustion mode is selected at the SI timing, the exhaust valve timing control means (ECU 2, steps 31 to 35) for controlling the HCCI timing when the HCCI combustion mode is selected, and the combustion mode selected by the combustion mode selection means are After switching from SI combustion mode to HCCI combustion mode, exhaust valve timing The exhaust valve timing is determined based on the determination result of the exhaust valve timing switching determination means (ECU2, step 36) and the exhaust valve timing switching determination means for determining whether or not the engine is actually switched from the SI timing to the HCCI timing. A first correction is made to correct the calculated first fuel supply amount to the decreasing side until a predetermined time (a time corresponding to ΔT · 3) elapses from the switching point at which the SI timing is actually switched to the HCCI timing. And a fuel supply amount correcting means (ECU2, steps 63, 64, 68).

  According to the control device for the internal combustion engine, the first fuel supply amount is calculated as the fuel supply amount by the first fuel supply device, one of the SI combustion mode and the HCCI combustion mode is selected as the combustion mode, and the exhaust valve timing Are controlled to SI timing when the SI combustion mode is selected and to HCCI timing when the HCCI combustion mode is selected, and the selected combustion mode is switched from the SI combustion mode to the HCCI combustion mode. After the switching, it is determined whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing. Then, the calculated first fuel supply amount is corrected to the decrease side until a predetermined time elapses from the switching time point when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. As described above, when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, the temperature in the combustion chamber becomes higher than the temperature suitable for compressive ignition combustion of the air-fuel mixture. The timing is earlier than the optimal timing, and the combustion state may become unstable. On the other hand, according to the control apparatus for an internal combustion engine, the calculated first fuel is calculated until a predetermined time elapses from the switching time when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. Since the supply amount is corrected to the decreasing side, the air-fuel ratio of the air-fuel mixture in the combustion chamber is made lean, and the reaction probability of the fuel and oxygen decreases, so that the temperature in the combustion chamber causes the air-fuel mixture to undergo compression ignition combustion. It is possible to suppress the temperature from becoming higher than a suitable temperature, and the self-ignition timing of the air-fuel mixture can be controlled to an optimal timing. Thereby, even when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, a stable combustion state can be ensured while suppressing an increase in torque fluctuation and occurrence of knocking. As a result, merchantability can be improved.

  According to a second aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the first aspect, the first fuel supply amount correcting means decreases the first fuel supply amount as the elapsed time from the switching time becomes longer. The correction is performed so that the correction degree to the side becomes smaller (steps 63 and 64).

  In general, in an internal combustion engine that can be operated by switching the combustion mode between the HCCI combustion mode and the SI combustion mode, when the combustion mode is switched from the HCCI combustion mode to the SI combustion mode, from the time of switching from the SI combustion mode to the HCCI combustion mode. As the time elapses and the operation in the HCCI combustion mode proceeds, the temperature in the combustion chamber decreases. On the other hand, according to the control device for the internal combustion engine, the first fuel supply amount is corrected so that the correction degree to the decrease side becomes smaller as the elapsed time from the switching time becomes longer. As the indoor temperature decreases, the first fuel supply amount can be gradually increased. Thereby, the torque of the internal combustion engine can be generated while controlling the self-ignition timing of the air-fuel mixture to the optimum timing. As a result, drivability can be improved.

  According to a third aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the first or second aspect, when the internal combustion engine is in the HCCI combustion mode, the second fuel supply device (second fuel injection valve 12) is used. Fuel is supplied into the combustion chamber 3d in the compression stroke, and second supply timing calculation means (ECU2, step 86) for calculating the second supply timing (second injection timing TINJD) as the fuel supply timing by the second fuel supply device. And second supply timing correction means (ECU2, ECU2) for correcting the calculated second supply timing to a more retarded side until a predetermined time elapses from the switching time based on the determination result of the exhaust valve timing switching determination means. Steps 85 and 86).

  According to the control device for an internal combustion engine, the second supply timing is calculated as the fuel supply timing by the second fuel supply device, and the calculated second supply timing is further increased until a predetermined time elapses from the switching time. Since it is corrected to the retarded angle side, as described above, when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, the temperature in the combustion chamber is higher than the temperature suitable for causing the mixture to undergo compression ignition combustion. Even when the engine is in a high state, the self-ignition timing of the air-fuel mixture can be shifted to the retard side to the optimum timing. Thereby, even when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, a more stable combustion state can be ensured.

  According to a fourth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the third aspect, the second supply timing correction means sets the second supply timing (second injection timing TINJD) to the elapsed time from the switching time. It is characterized in that the correction is performed so that the degree of correction toward the retard angle side becomes smaller as the length becomes longer.

  According to this control device for an internal combustion engine, the second supply timing is corrected so that the degree of correction to the retard side becomes smaller as the elapsed time from the switching time becomes longer. As the indoor temperature decreases, the first supply time can be gradually advanced. Thereby, the torque of the internal combustion engine can be generated while controlling the self-ignition timing of the air-fuel mixture to the optimum timing. As a result, drivability can be improved.

  The invention according to claim 5 is configured to be operable by switching the combustion mode between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition. The exhaust valve timing which is the valve timing of the exhaust valve 5 is changed by the timing changing device (exhaust VT switching mechanism 7), and the fuel is supplied by the first fuel supply device (first fuel injection valve 11) in the HCCI combustion mode. In the internal combustion engine 3 in which fuel is supplied into the combustion chamber 3d in the intake stroke and fuel is supplied into the combustion chamber 3d in the compression stroke by the second fuel supply device (second fuel injection valve 12), respectively, via the exhaust valve timing changing device. The exhaust valve timing is controlled, and the first fuel supply device (first fuel injection valve 11) is connected via the first fuel supply device (first fuel injection valve 11). The fuel supply amount and the supply timing by the first fuel injection valve 11) are controlled, and by the second fuel supply device (second fuel injection valve 12) via the second fuel supply device (second fuel injection valve 12). A control device 1 for an internal combustion engine 3 that controls the amount and timing of fuel supply, and a second supply timing for calculating a second supply timing (second injection timing TINJD) as a fuel supply timing by the second fuel supply device Based on the calculation means (ECU2, step 86), the combustion mode selection means (ECU2, steps 12, 13) for selecting one of the SI combustion mode and the HCCI combustion mode as the combustion mode, and the selection result of the combustion mode selection means, The exhaust valve timing is set to the SI timing when the SI combustion mode is selected, and to the HCCI timing when the HCCI combustion mode is selected. After the combustion mode selected by the exhaust valve timing control means (ECU 2, steps 31 to 35) and the combustion mode selection means are switched from the SI combustion mode to the HCCI combustion mode, the exhaust valve timing becomes the SI timing. Until a predetermined time elapses from the switching point based on the determination result of the exhaust valve timing switching determining means (ECU2, step 36) for determining whether or not the actual switching to the HCCI timing is performed. And a second supply timing correction means (ECU2, steps 85 and 86) for correcting the calculated second supply timing to the retarded angle side.

  According to the control device for an internal combustion engine, the same effect as that of the invention according to claim 3 can be obtained.

  According to a sixth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to the fifth aspect, the second supply timing correction means sets the second supply timing (second injection timing TINJD) to the elapsed time from the switching time. It is characterized in that the correction is performed so that the degree of correction toward the retard angle side becomes smaller as the length becomes longer.

  According to the control device for an internal combustion engine, the same effect as that of the invention according to claim 4 can be obtained.

  The invention according to claim 7 is configured to be operable by switching the combustion mode between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition. The exhaust valve timing which is the valve timing of the exhaust valve 5 is changed by the timing changing device (exhaust VT switching mechanism 7), and the internal combustion in which the ignition of the air-fuel mixture by the spark plug 10 is also executed in the HCCI combustion mode. In the engine, a control device for an internal combustion engine that controls the ignition timing of an air-fuel mixture via an ignition plug 10, and an ignition timing calculation means (ECU 2, steps 101 to 101) that calculates an ignition timing IGLOG of the air-fuel mixture by the ignition plug 10. 104) and one of SI combustion mode and HCCI combustion mode is selected as the combustion mode HCCI combustion mode is selected based on the selection result of the combustion mode selection means (ECU 2, steps 12 and 13) and the combustion mode selection means, and the exhaust valve timing is set to the SI timing when the SI combustion mode is selected. When the combustion mode selected by the exhaust valve timing control means (ECU2, steps 31 to 35) and the combustion mode selection means respectively switches to the HCCI combustion mode from the SI combustion mode. Based on the determination result of the exhaust valve timing switching determining means (ECU2, step 36) for determining whether or not the valve timing has actually switched from the SI timing to the HCCI timing, and the exhaust valve timing switching determining means, Is the timing for SI? Ignition timing correction means (ECU2, steps 101 to 104) for correcting the calculated ignition timing IGLOG to the retard side until a predetermined time elapses from the switching time point at which the timing is actually switched to the HCCI timing. It is characterized by that.

  According to this control device for an internal combustion engine, the ignition timing by the spark plug is calculated, one of the SI combustion mode and the HCCI combustion mode is selected as the combustion mode, and the exhaust valve timing is selected when the SI combustion mode is selected. When the HCCI combustion mode is selected as the SI timing, the HCCI timing is controlled, and after the selected combustion mode is switched from the SI combustion mode to the HCCI combustion mode, the exhaust valve timing is changed to the SI timing. It is determined whether or not the timing has actually switched to the HCCI timing. The calculated ignition timing is corrected to the retarded side until a predetermined time elapses from the switching time when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. As described above, when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, the temperature in the combustion chamber becomes higher than the temperature suitable for compressive ignition combustion of the air-fuel mixture. The timing is earlier than the optimal timing, and the combustion state may become unstable. On the other hand, according to the control apparatus for an internal combustion engine, the calculated ignition timing is maintained until a predetermined time elapses from the switching time point when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. Since it is corrected to the retarded angle side, it is possible to suppress the temperature in the combustion chamber from becoming higher than the temperature suitable for compressive ignition combustion of the air-fuel mixture, and the self-ignition timing of the air-fuel mixture can be controlled to the optimum timing. it can. Thereby, even when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, a stable combustion state can be ensured while suppressing an increase in torque fluctuation and occurrence of knocking. As a result, merchantability can be improved.

  According to an eighth aspect of the present invention, in the control device for an internal combustion engine according to the seventh aspect, the ignition timing correction means adjusts the ignition timing IGLOG to the retard side as the elapsed time from the switching time becomes longer. The correction is performed so as to be smaller.

  According to the control device for an internal combustion engine, the ignition timing is corrected so that the degree of correction to the retard side becomes smaller as the elapsed time from the switching time becomes longer. As the temperature decreases, the ignition timing can be gradually advanced. Thereby, the torque of the internal combustion engine can be generated while controlling the self-ignition timing of the air-fuel mixture to the optimum timing. As a result, drivability can be improved.

  According to a ninth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to any one of the first to eighth aspects, the exhaust valve timing changing device is a hydraulically driven exhaust valve timing driven by hydraulic oil pressure. Correlation parameter detecting means (ECU2, water temperature) which is constituted by a change device (exhaust VT switching mechanism 7) and detects a correlation parameter (engine water temperature TW) having a correlation with at least one of hydraulic oil pressure and oil temperature. A sensor 21), and the exhaust valve timing switching determination means determines whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the detected correlation parameter. (ECU2, steps 36, 49 to 51).

  Like this internal combustion engine, when the hydraulically driven exhaust valve timing changing device is driven by hydraulic oil pressure and the exhaust valve timing is switched from the SI timing to the HCCI timing, the exhaust valve timing is actually switched. The time required for is highly dependent on the hydraulic pressure and / or the oil temperature of the hydraulic oil, and has a high correlation with both. Therefore, according to the control apparatus for an internal combustion engine, the exhaust valve timing is actually changed from the SI timing to the HCCI timing in accordance with the correlation parameter having correlation with at least one of the hydraulic oil pressure and the oil temperature. Since it is determined whether or not it has been switched, this determination can be made with high accuracy. As a result, the control accuracy can be improved.

  According to a tenth aspect of the present invention, in the control device 1 for the internal combustion engine 3 according to any one of the first to eighth aspects, a combustion state parameter detecting means for detecting a combustion state parameter representing a combustion state of the air-fuel mixture in the combustion chamber ( ECU 2 and an in-cylinder pressure sensor), and the exhaust valve timing switching determination means determines whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the detected combustion state parameter. It is characterized by that.

  As in this internal combustion engine, when the exhaust valve timing is switched from the SI timing to the HCCI timing, the combustion state of the air-fuel mixture in the combustion chamber changes with the switching of the exhaust valve timing. This change reflects the fact that the exhaust valve timing has actually switched. Therefore, according to the control device for the internal combustion engine, it is determined whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the combustion state parameter representing the combustion state of the air-fuel mixture in the combustion chamber. Therefore, this determination can be performed with high accuracy. As a result, the control accuracy can be improved.

It is a figure which shows typically the structure of a part of control apparatus which concerns on one Embodiment of this invention, and the internal combustion engine to which this is applied. It is a block diagram which shows the electric constitution of a control apparatus. It is a figure which shows the valve lift curve of an intake valve and an exhaust valve for demonstrating operation | movement of an intake lift switching mechanism and an exhaust lift switching mechanism. It is a flowchart which shows various control processing. It is a flowchart which shows a combustion mode determination process. It is a figure which shows an example of the map used for determination of a driving | operation area | region. It is a flowchart which shows a valve timing control process. It is a flowchart which shows an exhaust VT control process. 6 is a flowchart showing an exhaust VT determination process. It is a flowchart which shows a fuel-injection control process. It is a figure which shows an example of the map used for calculation of the injection quantity correction coefficient KLES2H. It is a flowchart which shows the calculation process of injection timing. It is a figure which shows an example of the map used for calculation of the injection timing correction value DTINJS2H. It is a flowchart which shows an ignition timing control process. It is a figure which shows an example of the map used for calculation of the ignition timing correction value DIGS2H. It is a timing chart which shows an example of a control result.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described with reference to the drawings. As will be described later, the control device 1 of the present embodiment controls the combustion mode of the internal combustion engine (hereinafter referred to as “engine”) 3 shown in FIG. 1, and includes an ECU 2 shown in FIG. The ECU 2 executes various control processes such as a valve timing control process described later.

  The engine 3 is an in-line four-cylinder gasoline engine having four sets of cylinders 3a and pistons 3b (only one set is shown). The engine 3 is mounted on a vehicle (not shown) and includes a piston 3b and a cylinder head 3c of each cylinder 3a. A combustion chamber 3d is formed between them.

  Further, the engine 3 drives the intake valve 4 and the exhaust valve 5 provided for each cylinder 3a to open and close, the intake valve 4 to open and close, the intake VT switching mechanism 6 to switch the valve timing, and the exhaust valve 5 to open and close. In addition, an exhaust VT switching mechanism 7 for switching the valve timing is provided.

  The intake VT switching mechanism 6 has the same configuration as that already proposed by the present applicant in Japanese Patent Laid-Open No. 2000-227013, etc., and a detailed description thereof is omitted here, but the valve timing of the intake valve 4 is omitted. (Hereinafter referred to as “intake valve timing”) is switched between two stages of a high speed valve timing and a low speed valve timing, and a low speed cam and a high speed cam (both not shown) provided integrally with the intake camshaft, A low-speed rocker arm and a high-speed rocker arm (both not shown) that are rotatably attached to the intake rocker arm shaft are provided.

  The intake VT switching mechanism 6 is of a hydraulic drive type, and is connected to a hydraulic pump (not shown) via an oil passage (not shown) and an intake VT control valve 6a (see FIG. 2). This hydraulic pump is connected to the crankshaft 3e and is driven by the power during operation of the engine 3 to supply hydraulic pressure to an intake VT control valve 6a and an exhaust VT control valve 7a (described later) (see FIG. 2).

  The intake VT switching mechanism 6 holds the intake valve timing at the low speed valve timing when the hydraulic pressure is not supplied, and switches the intake valve timing from the low speed valve timing to the high speed valve timing when the hydraulic pressure is supplied. The intake VT control valve 6a is a normally closed electromagnetic valve electrically connected to the ECU 2. The intake VT control valve 6a is in a closed state when OFF and supplies hydraulic pressure from the hydraulic pump to the intake VT switching mechanism 6 side. And is opened when turned on by a control input signal from the ECU 2 to supply the hydraulic pressure from the hydraulic pump to the intake VT switching mechanism 6 side. With the above configuration, the operation mode of the intake VT switching mechanism 6 is switched to the high speed valve timing mode / low speed valve timing mode according to the ON / OFF state of the intake VT control valve 6a.

  In this low-speed valve timing mode, during the rotation of the intake camshaft, the intake valve 4 is opened / closed only by the low-speed rocker arm, so that it opens according to the valve lift curve shown by the solid line in FIG. It's time. On the other hand, in the high-speed valve timing mode, during the rotation of the intake camshaft, the intake valve 4 is driven only by the high-speed cam and opens according to the valve lift curve shown by the broken line in FIG. It's time. As shown in the figure, at this high speed valve timing, the maximum lift of the intake valve 4 is larger than that at the low speed valve timing, and the valve opening timing of the intake valve 4 is more advanced and the valve closing timing is higher. The valve opening period becomes longer when the is more retarded. As a result, air is sucked into the cylinder 3a with higher charging efficiency.

  The exhaust VT switching mechanism 7 serving as an exhaust valve timing changing device switches the valve timing of the exhaust valve 5 (hereinafter referred to as “exhaust valve timing”) into two stages of a high speed valve timing and a low speed valve timing. Specifically, it is configured similarly to the intake VT switching mechanism 6. That is, the exhaust VT switching mechanism 7 is also of a hydraulic drive type, and is connected to the above-described hydraulic pump via an oil passage (not shown) and an exhaust VT control valve 7a. The timing is maintained at the low speed valve timing, and when the hydraulic pressure is supplied, the exhaust valve timing is switched from the low speed valve timing to the high speed valve timing.

  Similarly to the intake VT control valve 6a, the exhaust VT control valve 7a is also composed of a normally-open electromagnetic valve electrically connected to the ECU 2. The hydraulic pressure supply to the exhaust VT switching mechanism 7 side is stopped and the valve is opened when turned on by a control input signal from the ECU 2 to supply the hydraulic pressure from the hydraulic pump to the exhaust VT switching mechanism 7 side. With the above configuration, in the exhaust VT switching mechanism 7, the operation mode is switched between the high speed valve timing mode and the low speed valve timing mode according to the ON / OFF state of the exhaust VT control valve 7a.

  In this high-speed valve timing mode, the exhaust valve 5 is driven only by the high-speed cam during rotation of the exhaust camshaft, and opens according to the valve lift curve shown by the broken line in FIG. It becomes. On the other hand, in the low-speed valve timing mode, the exhaust valve 5 is opened / closed only by the low-speed rocker arm during the rotation of the exhaust camshaft, thereby opening the valve according to the valve lift curve shown by the solid line in FIG. It becomes valve timing.

  As shown in the figure, in the low speed valve timing, the valve opening timing of the exhaust valve 5 becomes more retarded and the valve closing timing becomes more advanced compared to the high speed valve timing. Becomes shorter and the maximum lift of the exhaust valve 5 becomes smaller. In addition to this, there is no valve overlap. As a result, the amount of burned gas remaining in the combustion chamber 3d, that is, the internal EGR amount increases.

  In this embodiment, as will be described later, the exhaust valve timing is set to the low speed valve timing in the HCCI combustion mode, and the high speed valve timing in the SI combustion mode. The low-speed valve timing is called “HCCI timing”, and the high-speed valve timing is called “SI timing”. Further, since the exhaust VT switching mechanism 7 is hydraulically driven, the response is low, and the time required from the start to the completion of the switching operation when switching the operation mode is relatively long. .

  Further, the engine 3 includes an ignition plug 10, a first fuel injection valve 11, and a second fuel injection valve 12. Each of the ignition plug 10 and the two fuel injection valves 11, 12 is provided for each cylinder 3a. Provided (only one is shown). The first fuel injection valve 11 is attached to a branch portion of the intake manifold so as to inject fuel into the intake port 8a of each cylinder 3a, and the second fuel injection valve 12 directly supplies the fuel into the combustion chamber 3d. It is attached to the cylinder head 3c so as to inject. In the present embodiment, the first and second fuel injection valves 11 and 12 correspond to the first and second fuel supply devices, respectively.

  The spark plug 10 and the two fuel injection valves 11 and 12 are both electrically connected to the ECU 2, and as will be described later, the fuel injection amount and the injection timing of the fuel by the two fuel injection valves 11 and 12 are controlled by the ECU 2. And the ignition timing of the air-fuel mixture by the spark plug 10 are controlled. Thus, the engine 3 is operated by switching between an HCCI operation in which the air-fuel mixture is combusted by premixed compression ignition and an SI operation in which the air-fuel mixture is combusted by spark ignition.

  As shown in FIG. 2, a crank angle sensor 20, a water temperature sensor 21, an accelerator opening sensor 22, and an air flow sensor 23 are electrically connected to the ECU 2. The crank angle sensor 20 includes a magnet rotor and an MRE pickup, and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3e rotates.

  The CRK signal is output at one pulse every predetermined crank angle (for example, 1 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston of each cylinder is at a predetermined crank angle position slightly ahead of the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle.

  Further, the water temperature sensor 21 detects the engine water temperature TW, which is the temperature of the cooling water circulating in the cylinder block of the engine 3, and outputs a detection signal representing it to the ECU 2. In the present embodiment, the water temperature sensor 21 corresponds to the correlation parameter detection means, and the engine water temperature TW corresponds to the correlation parameter. Further, the accelerator opening sensor 22 detects an accelerator opening AP, which is an operation amount of an accelerator pedal (not shown), and outputs a detection signal representing the detected value to the ECU 2.

  Further, the air flow sensor 23 is constituted by a hot-wire air flow meter, and is disposed upstream of the throttle valve 9 in the intake passage 8 and detects the flow rate of fresh air flowing in the intake passage 8. A detection signal representing it is output to the ECU 2. The ECU 2 calculates an intake air amount GCYL to be taken into the cylinder 3a based on the detection signal of the air flow sensor 23.

  On the other hand, the ECU 2 is composed of a microcomputer including a CPU, RAM, ROM, an I / O interface (all not shown), and the like, and the engine 2 is based on the detection signals of the various sensors 20 to 23 described above. 3, and various controls such as a combustion mode determination process and a fuel injection control process are executed as described below.

  In this embodiment, the ECU 2 includes a first fuel supply amount calculation means, a combustion mode selection means, an exhaust valve timing control means, an exhaust valve timing switching determination means, a first fuel supply amount correction means, a correlation parameter detection means, It corresponds to a second supply timing calculation means, a second supply timing correction means, an ignition timing calculation means, and an ignition timing correction means.

  Next, various control processes executed by the ECU 2 at a predetermined control cycle ΔT will be described with reference to FIG. As shown in the figure, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), the required torque PMCMD is calculated. This required torque PMCMD is calculated by searching a map (not shown) according to the engine speed NE and the accelerator pedal opening AP.

  Subsequently, it progresses to step 2 and a combustion mode determination process is performed. This combustion mode determination process determines whether the HCCI combustion mode is to be executed or the SI combustion mode is to be executed as the combustion mode, and is specifically executed as shown in FIG. First, in step 10, it is determined whether or not the engine coolant temperature TW is higher than a predetermined value TWHCCI. The predetermined value TWHCCI is set to a lower limit value of the engine coolant temperature TW that can execute the HCCI combustion mode.

  When the determination result is YES and TW> TWHCCI, the process proceeds to step 11 and the operation range of the engine 3 is determined to be in the HCCI combustion mode by searching the map shown in FIG. 6 according to the required torque PMCMD and the engine speed NE. Is in the HCCI area (area indicated by hatching in the figure) to be executed.

  When the determination result is YES and the operation region of the engine 3 is in the HCCI region, it is determined that the execution condition of the HCCI combustion mode is satisfied, and the process proceeds to Step 12 to express it, the HCCI combustion mode flag F_HCCI is set to “1”. Thereafter, this process is terminated.

  On the other hand, when the determination result of any of the above steps 10 and 11 is NO, that is, when TW ≦ TWHCCI is established, or when the operation region of the engine 3 is in the SI region, the execution condition of the HCCI combustion mode Is not established and the SI combustion mode should be executed, the process proceeds to step 13 and the HCCI combustion mode flag F_HCCI is set to “0” to indicate that. Thereafter, this process is terminated.

  Returning to FIG. 4, after performing the combustion mode determination process in Step 2 as described above, the process proceeds to Step 3 to execute the valve timing control process. This valve timing control process controls the intake valve timing and the exhaust valve timing via the intake VT switching mechanism 6 and the exhaust VT switching mechanism 7, respectively, and details thereof will be described later.

  Next, the routine proceeds to step 4 where a fuel injection control process is executed. This control process calculates the valve opening time and valve opening timing of the first fuel injection valve 11 and the second fuel injection valve 12, and details thereof will be described later.

  In step 5 following step 4, the ignition timing control process is executed, and then this process is terminated. This control process calculates the discharge timing of the spark plug 10, that is, the ignition timing, and details thereof will be described later.

  Hereinafter, the valve timing control process described above will be described with reference to FIG. As shown in the figure, first, at step 20, an intake VT control process is executed. In this intake VT control process, the ON / OFF state of the intake VT control valve 6a is controlled in accordance with the operating state of the engine 3 such as the engine speed NE and the required torque PMCMD, whereby the intake VT control mechanism 6 is connected. Thus, the intake valve timing is controlled to one of the high speed valve timing and the low speed valve timing.

  Next, the routine proceeds to step 21 where exhaust VT control processing is executed. Specifically, the exhaust VT control process is executed as shown in FIG. First, in step 30, the exhaust VT setting flag F_VTECEXS stored in the RAM is set as its previous value F_VTECEXz.

  Next, the routine proceeds to step 31, where it is determined whether or not the above-described HCCI combustion mode flag F_HCCI is “1”. If this determination result is YES and the execution condition of the HCCI combustion mode is satisfied, it is determined that the exhaust valve timing should be set to the HCCI timing in order to execute the HCCI combustion mode, and the process proceeds to Step 32. In order to express this, the exhaust VT setting flag F_VTECEXS is set to “1”.

  Next, in step 33, the exhaust VT control valve 7a is held in the OFF state without supplying a control input signal to the exhaust VT control valve 7a. Thereby, the hydraulic pressure supply to the exhaust VT switching mechanism 7 is stopped so that the exhaust valve timing becomes the HCCI timing.

  On the other hand, when the determination result in step 31 is NO and the execution condition of the HCCI combustion mode is not satisfied, it is determined that the exhaust valve timing should be set to the SI timing in order to execute the SI combustion mode. Proceeding to step 34, in order to represent this, the exhaust VT setting flag F_VTECEXS is set to "0".

  Next, the process proceeds to step 35, where the control input signal is supplied to the exhaust VT control valve 7a, and the exhaust VT control valve 7a is driven to the ON state. Thereby, the hydraulic pressure of the hydraulic pump is supplied to the exhaust VT switching mechanism 7 so that the exhaust valve timing becomes the SI timing.

  In step 36 following step 33 or 35 described above, as described below, after executing the exhaust VT determination processing, this processing is terminated.

  Next, the exhaust VT determination process will be described with reference to FIG. As shown in the figure, first, in step 40, it is determined whether or not the exhaust VT setting flag F_VTECEXS described above is “0”. When the determination result is YES, the process proceeds to step 41 to determine whether or not the previous value F_VTECEXz of the exhaust VT setting flag is “1”. When the determination result is NO, the process proceeds to Step 44 described later.

  On the other hand, when the determination result in step 41 is YES, that is, when the current loop is a loop immediately after the exhaust valve timing is switched from the HCCI timing to the SI timing, the routine proceeds to step 42 where the engine speed NE and The SI-side switching value CVTECESM is calculated by searching a map (not shown) according to the engine coolant temperature TW. This SI-side switching value CVTECESM is required until the exhaust valve timing is actually switched to the HCCI timing when the exhaust VT switching mechanism 7 is driven and the exhaust valve timing is switched from the HCCI timing to the SI timing. It is an estimate of time.

  Next, the routine proceeds to step 43, where the count value CVTECEX of the exhaust VT switching counter is set to the SI side switching value CVTECESM.

  In step 44 following step 41 or 43 described above, it is determined whether or not the count value CVTECEX of the exhaust VT switching counter is 0. When the determination result is NO, it is determined that the exhaust valve timing is not actually switched to the SI timing, the process proceeds to step 45, and the count value CVTECEX of the exhaust VT switching counter is decremented by a value 1.

  Next, the routine proceeds to step 46, where the exhaust VT determination flag F_VTECEXF is set to “1” to indicate that the exhaust valve timing is still at the HCCI timing. Thereafter, this process is terminated.

  On the other hand, when the determination result in step 44 is YES, it is determined that the exhaust valve timing has actually been switched to the SI timing, the process proceeds to step 47, and the exhaust VT determination flag F_VTECEXF is set to “0”. Thereafter, this process is terminated.

  On the other hand, when the determination result of step 40 is NO, the process proceeds to step 48 to determine whether or not the previous value F_VTECEXz of the exhaust VT setting flag is “0”. When the determination result is NO, the process proceeds to Step 51 described later.

  On the other hand, when the determination result in step 48 is YES, that is, when the current loop is a loop immediately after the exhaust valve timing is switched from the SI timing to the HCCI timing, the routine proceeds to step 49 where the engine speed NE and By searching a map (not shown) according to the engine coolant temperature TW, an HCCI-side switching value CVTECEHM is calculated. This HCCI side switching value CVTECEHM estimates the time required for the exhaust valve timing to actually switch to the HCCI timing when the exhaust VT switching mechanism 7 switches the exhaust valve timing from the SI timing to the HCCI timing. It is what.

  Next, the routine proceeds to step 50, where the count value CVTECEX of the exhaust VT switching counter is set to the HCCI side switching value CVTECEHM.

  In step 51 following step 48 or 50 described above, it is determined whether the count value CVTECEX of the exhaust VT switching counter is 0 or not. When the determination result is NO, it is determined that the exhaust valve timing is not actually switched to the HCCI timing, the process proceeds to step 52, and the count value CVTECEX of the exhaust VT switching counter is decremented by a value of 1.

  Next, the routine proceeds to step 53, where the exhaust VT determination flag F_VTECEXF is set to “0” to indicate that the exhaust valve timing is still at the SI timing. Thereafter, this process is terminated.

  On the other hand, when the determination result in step 51 is YES, it is determined that the exhaust valve timing is actually switched to the HCCI timing, the process proceeds to step 46 described above, and the exhaust VT determination flag F_VTECEXF is set to “1”. Thereafter, this process is terminated.

  Next, the above-described fuel injection control process will be described with reference to FIG. As will be described below, this control process calculates the fuel injection amount and the injection timing by the two fuel injection valves 11 and 12, that is, the valve opening time and the valve opening timing.

  As shown in the figure, first, in step 60, it is determined whether or not the exhaust VT determination flag F_VTECEXF described above is “1”. When the determination result is NO and the exhaust valve timing is set to the SI timing, the routine proceeds to step 61, where the count value CKLES2H of the injection amount correction counter is set to the value 0. Next, at step 62, the injection amount correction coefficient KLES2H is set to a value of 1.0.

  On the other hand, if the determination result in step 60 is YES and the exhaust valve timing is set to the HCCI timing, the routine proceeds to step 63, where the count value CKLES2H of the injection correction counter is incremented by the value 1.

  Next, the routine proceeds to step 64, where an injection amount correction coefficient KLES2H is calculated by searching the map shown in FIG. 11 according to the count value CKLES2H of the injection correction counter. As shown in the figure, in this map, the injection amount correction coefficient KLES2H is set to a positive value smaller than the value 1 in the region of CKLES2H ≦ 4. More specifically, the injection amount correction coefficient KLES2H is set to a predetermined value KLREF (0 <KLREF <1) when CKLES2H = 1, and approaches the value 1 as the count value CKLES2H of the injection correction counter increases. While increasing in steps, the degree of increase is set smaller.

  In step 65 following step 62 or 64 described above, a basic fuel injection amount GFMAFM is calculated by searching a map (not shown) according to the intake air amount GCYL described above. Next, the routine proceeds to step 66, where a target equivalence ratio KCMD is calculated by searching a map (not shown) according to the engine speed NE and the required torque PMCMD.

  Next, in step 67, a second fuel injection amount GFOUTD is calculated by searching a map (not shown) according to the operating state such as the engine speed NE, the required torque PMCMD and the engine water temperature TW. This second fuel injection amount GFOUTD is calculated as the fuel amount to be injected by the second fuel injection valve 12.

In step 68 following step 67, the first fuel injection amount GFOUTP (first fuel supply amount) is calculated by the following equation (1). The first fuel injection amount GFOUTP is calculated as a fuel amount to be injected by the first fuel injection valve 11.
GFOUTP = GFMAFM / KCMD / KLES2H-GFOUTD (1)

  As is apparent from this equation (1), the first fuel injection amount GFOUTP is calculated using the injection amount correction coefficient KLES2H as a multiplication coefficient by which the basic fuel injection amount GFMAFM is multiplied. Therefore, the injection amount correction coefficient KLES2H The smaller the value, the smaller the calculated value. In this case, since the injection amount correction coefficient KLES2H is set as shown in FIG. 11, the first fuel injection amount GFOUTP is corrected immediately after the exhaust valve timing is switched from the SI timing to the HCCI timing. The coefficient KLES2H is corrected so as to be smaller than the value when KLES2H = 1. Thereafter, as the control proceeds, the first fuel injection amount GFOUTP gradually increases so as to approach the value when KLES2H = 1, and the degree of increase approaches the value when KLES2H = 1. Smaller.

  That is, the first fuel injection amount GFOUTP is calculated so that the correction degree to the decrease side by the injection amount correction coefficient KLES2H gradually decreases after switching from the SI timing to the HCCI timing. As a result, when the exhaust valve timing is switched from the SI timing to the HCCI timing, the temperature in the combustion chamber 3d can be maintained at a temperature suitable for compression ignition combustion, and an increase in torque fluctuation is suppressed. However, the torque of the engine 3 can be increased. In order to obtain the above effects, the injection amount correction coefficient KLES2H is set as shown in FIG.

  Next, the routine proceeds to step 69, where the second injection time TOUTD is calculated by correcting the second fuel injection amount GFOUTD in accordance with the fuel pressure supplied to the second fuel injection valve 12. The second injection time TOUTD corresponds to the valve opening time of the second fuel injection valve 12.

  Next, in step 70, the first injection time TOUTP is calculated by correcting the first fuel injection amount GFOUTP according to the fuel pressure supplied to the first fuel injection valve 11. The first injection time TOUTP corresponds to the valve opening time of the first fuel injection valve 11.

  In step 71 following step 70, an injection timing calculation process is executed. This calculation process calculates a first injection timing TINJP that is the opening timing of the first fuel injection valve 11 and a second injection timing TINJD (second supply timing) that is the opening timing of the second fuel injection valve 12. Specifically, it is executed as shown in FIG. The first injection timing TINJP and the second injection timing TINJD are calculated as timings during the intake stroke and the compression stroke, respectively.

  As shown in the figure, first, at step 80, it is determined whether or not the exhaust VT determination flag F_VTECEXF described above is “1”. When the determination result is YES and the exhaust valve timing is set to the HCCI timing, the process proceeds to step 81 where the first injection is performed by searching a map (not shown) according to the engine speed NE and the required torque PMCMD. The HCCI value TINJP_HC for the time is calculated.

  Next, the routine proceeds to step 82 where the first injection timing TINJP is set to the HCCI value TINJP_HC.

  Next, in step 83, a HCCI value TINJD_HC for the second injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque PMCMD. The HCCI value TINJD_HC at the second injection timing is calculated such that the crank angle at the TDC position in the compression stroke is 0, and the greater the value is, the closer to the TDC position, the more positive the value.

  In step 84 following step 83, the basic value TINJD_MAP of the second injection timing is set to the value TINJD_HC for HCCI. Next, the routine proceeds to step 85, where an injection timing correction value DTINJS2H is calculated by searching the map shown in FIG. 13 according to the count value CKLES2H of the injection correction counter described above. As shown in the figure, in this map, the injection timing correction value DTINJS2H is set to a negative value in the region of CKLES2H ≦ 4. More specifically, the injection timing correction value DTINJS2H is set to a negative predetermined value DTREF when CKLES2H = 1, and increases stepwise to approach the value 0 as the count value CKLES2H of the injection correction counter increases. At the same time, the degree of increase is set to be smaller.

  Next, the routine proceeds to step 86, where the second injection timing TINJD is set to the sum TINJD_MAP + DTINJS2H of the basic value and the injection timing correction value, and then this processing is terminated.

  Thus, since the second injection timing TINJD is calculated by adding the injection timing correction value DTINJS2H to the basic value TINJD_MAP, the larger the absolute value of the negative injection timing correction value DTINJS2H, the more retarded it is. Will be corrected. In this case, since the injection timing correction value DTINJS2H is set as shown in FIG. 13, the second injection timing TINJD is set to KLES2H by the injection timing correction value DTINJS2H immediately after switching the exhaust valve timing to the HCCI timing. It is corrected to the retard side from the value when = 1. Thereafter, as the control proceeds, the second injection timing TINJD is advanced stepwise so as to approach the value when KLES2H = 1, and the advance angle approaches the value when KLES2H = 1. The smaller it gets.

  That is, the second injection timing TINJD is calculated so that the degree of correction to the retard side by the injection timing correction value DTINJS2H gradually decreases after switching to the HCCI timing. As a result, when the exhaust valve timing is switched from the SI timing to the HCCI timing, the temperature in the combustion chamber 3d can be maintained at a temperature suitable for compression ignition combustion, and an increase in torque fluctuation is suppressed. However, the torque of the engine 3 can be increased. In order to obtain the above effects, the injection timing correction value DTINJS2H is set as shown in FIG.

  On the other hand, if the determination result in step 80 is NO and the exhaust valve timing is set to the SI timing, the routine proceeds to step 87, where a map (not shown) is searched according to the engine speed NE and the required torque PMCMD. Then, the SI value TINJP_SI for the first injection timing is calculated.

  Next, the routine proceeds to step 88, where the first injection timing TINJP is set to the SI value TINJP_SI.

  Next, in step 89, the SI value TINJD_SI for the second injection timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque PMCMD. In step 90 following step 89, the basic value TINJD_MAP of the second injection timing is set to the SI value TINJD_SI.

  Next, the routine proceeds to step 91, where the injection timing correction value DTINJS2H is set to 0. Next, as described above, after executing step 86, the present process is terminated.

  Returning to FIG. 10, in step 71, the injection timing calculation process is executed as described above, and then the fuel injection control process is terminated.

  Next, the ignition timing control process will be described with reference to FIG. In this ignition timing control process, the ignition timing IGLOG is calculated by the method described below, and the crank angle at the TDC position in the compression stroke is set to a value of 0. Calculated to be a value. In the case of the engine 3 of the present embodiment, since the air-fuel mixture is generated in a state in which self-ignition combustion occurs during the HCCI combustion mode, spark ignition is essentially unnecessary, but misfire prevention and self-ignition combustion are possible. For the purpose of appropriately controlling the timing, spark ignition by the spark plug 10 is executed even during the HCCI combustion mode. Therefore, as described below, the ignition timing IGLOG is calculated even during the HCCI combustion mode.

  As shown in the figure, first, in step 100, it is determined whether or not the exhaust VT determination flag F_VTECEXF described above is “1”. When the determination result is YES and the exhaust valve timing is set to the HCCI timing, the process proceeds to step 101, and by searching the map shown in FIG. 15 according to the count value CKLES2H of the injection correction counter described above, An ignition timing correction value DIGS2H is calculated.

  As shown in the figure, in this map, the ignition timing correction value DIGS2H is set to a negative value in the region of CKLES2H ≦ 4. More specifically, the ignition timing correction value DIGS2H is set to a negative predetermined value DIREF when CKLES2H = 1, and gradually increases so as to approach the value 0 as the count value CKLES2H of the injection correction counter increases. At the same time, the degree of increase is set to be smaller. That is, it is set so that the degree of correction to the retard side decreases.

  Next, the routine proceeds to step 102, where a HCCI value IG_HC for ignition timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque PMCMD.

  In step 103 following step 102, the ignition timing basic value IGMAP is set to the HCCI value IG_HC.

  Next, the routine proceeds to step 104, where the ignition timing IGLOG is set to the sum IGMAP + DIGS2H of the basic value and the ignition timing correction value. Thereafter, this process is terminated.

  As described above, the ignition timing IGLOG is calculated by adding the ignition timing correction value DIGS2H to the basic value IGMAP. Therefore, the larger the absolute value of the ignition timing correction value DIGS2H that is a negative value, the more the correction is made to the retard side. Will be. In this case, since the ignition timing correction value DIGS2H is set as shown in FIG. 15, the ignition timing IGLOG is set to KLES2H = 1 by the ignition timing correction value DIGS2H immediately after switching the exhaust valve timing to the HCCI timing. It is corrected to the retard side from the value at. Thereafter, as the control proceeds, the ignition timing IGLOG is advanced stepwise so as to approach the value when KLES2H = 1, and the degree of advancement approaches the value when KLES2H = 1. Smaller.

  That is, the ignition timing IGLOG is calculated so that the degree of correction to the retard side by the ignition timing correction value DIGS2H gradually decreases after switching to the HCCI timing. As a result, when the exhaust valve timing is switched from the SI timing to the HCCI timing, the temperature in the combustion chamber 3d can be maintained at a temperature suitable for compression ignition combustion, and an increase in torque fluctuation is suppressed. However, the torque of the engine 3 can be increased. In order to obtain the above effects, the ignition timing correction value DIGS2H is set as shown in FIG.

  On the other hand, when the determination result of step 100 is NO and the exhaust valve timing is set to the SI timing, the routine proceeds to step 105, where the injection timing correction value DTINJS2H is set to the value 0.

  Next, the routine proceeds to step 106, where a SI map value IG_SI of the ignition timing is calculated by searching a map (not shown) according to the engine speed NE and the required torque PMCMD.

  In step 107 following step 106, the ignition timing basic value IGMAP is set to the SI value IG_SI. Next, as described above, after executing step 104, the present process is terminated.

  Next, an example of control results when various control processes are executed by the control device 1 of the present embodiment configured as described above will be described with reference to FIG. As shown in the figure, the count value CVTECEX of the exhaust VT switching counter becomes HCCI at the timing (time t1) when the execution condition of the HCCI combustion mode is satisfied and the exhaust VT setting flag F_VTECEXS changes from “0” to “1”. The value is set to the side switching value CVTECEHM, and thereafter, the count value CVTECEX of the exhaust VT switching counter is decremented by 1 as the control proceeds.

  Then, at the timing when CVTECEX = 0 (time t2), the exhaust VT determination flag F_VTECEXF changes from “0” to “1”, and at the same time, the count value CKLES2H of the injection correction counter changes from the value 0 to the value 1. Accordingly, the injection amount correction coefficient KLES2H changes from the value 1 to the predetermined value KLREF, the injection timing correction value DTINJS2H changes from the value 0 to the predetermined value DTREF, and the ignition timing correction value DIGS2H changes from the value 0 to the predetermined value DIREF. Thereafter, as the count value CKLES2H of the injection correction counter is incremented by 1, the three values KLES2H, DTINJS2H, and DIGS2H each increase stepwise. Then, at the timing when CKLES2H = 4 is established, the injection amount correction coefficient KLES2H becomes the value 1, the injection timing correction value DTINJS2H becomes the value 0, and the ignition timing correction value DIGS2H becomes the value 0, so that the three values KLES2H, Correction by DTINJS2H and DIGS2H ends.

  As described above, according to the control device 1 of the present embodiment, the determination result of step 51 is YES, and when it is determined that the exhaust valve timing is actually switched from the SI timing to the HCCI timing, the exhaust VT The determination flag F_VTECEXF is set to “1”, and thereafter, in step 63, the count value CKLES2H of the injection correction counter is incremented by one. Then, until CKLES2H = 4 is satisfied, that is, until a predetermined time corresponding to ΔT · 3 has elapsed, the first fuel injection amount GFOUTP is reduced to the second injection timing by the injection amount correction coefficient KLES2H. TINJD is corrected to the retard side by the injection timing correction value DTINJS2H, and the ignition timing IGLOG is corrected to the retard side by the ignition timing correction value DIGS2H.

  Thereby, when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, it is possible to suppress the temperature in the combustion chamber from becoming higher than the temperature suitable for the compression ignition combustion of the mixture, and the self-ignition timing of the mixture Can be controlled at the optimum timing. As a result, even when the combustion mode is switched from the SI combustion mode to the HCCI combustion mode, a stable combustion state can be ensured while suppressing an increase in torque fluctuation and occurrence of knocking, thereby improving the merchantability. Can do.

  Further, according to the setting tendency of FIGS. 11, 12, and 15 described above, the degree of correction of the first fuel injection amount GFOUTP to the decrease side by the injection amount correction coefficient KLES2H, the retarded side of the second injection timing TINJD by the injection timing correction value DTINJS2H The degree of correction to the ignition timing and the degree of correction of the ignition timing IGLOG to the retard side by the ignition timing correction value DIGS2H are both smaller as time elapses after the exhaust valve timing is actually switched to the HCCI timing. . Accordingly, the first fuel injection amount GFOUTP can be gradually increased as the temperature in the combustion chamber decreases with the passage of time since the switching of the exhaust valve timing to the HCCI timing, and the second The injection timing TINJD and the ignition timing IGLOG can be gradually advanced. As a result, while maintaining the temperature in the combustion chamber at a temperature suitable for compression-ignition combustion of the air-fuel mixture and suppressing an increase in torque fluctuation, the torque of the engine 3 is an original value (that is, a value when there is no correction). Can be raised. As a result, drivability can be improved.

  Further, when the hydraulically driven exhaust VT switching mechanism 7 is driven with hydraulic oil and the exhaust valve timing is switched from the SI timing to the HCCI timing, the time required for actual switching is the hydraulic oil pressure and / or Or the dependence with respect to oil temperature is high, and has high correlation with both. On the other hand, according to the control device 1, whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the engine water temperature TW having a high correlation with the oil temperature of the hydraulic oil. This determination can be made with high accuracy. As a result, the control accuracy can be improved.

  The embodiment is an example in which the first fuel injection valve 11 is used as the first fuel supply device, but the first fuel supply device of the present invention is not limited to this, and the fuel is supplied in the HCCI combustion mode. What is necessary is just to supply in a combustion chamber by an intake stroke. For example, an in-cylinder direct injection fuel injection valve similar to the second fuel injection valve 12 of the embodiment may be used as the first fuel supply device, and in this case, the fuel is injected into the direct injection type fuel injection valve. From the intake stroke to the combustion chamber 3d.

  In the embodiment, in the fuel injection control process, the first fuel injection amount GFOUTP and the first injection timing TINJP by the first fuel injection valve 11, the second fuel injection amount GFOUTD and the second injection by the second fuel injection valve 12 are used. Although it is an example configured to execute the HCCI combustion mode by controlling the timing TINJD, the method of the fuel injection control process for executing the HCCI combustion mode of the present invention is not limited to this, and the HCCI combustion mode As long as it can be executed.

  For example, in the HCCI combustion mode, the second fuel injection valve 12 may be stopped and only the fuel injection in the intake stroke by the first fuel injection valve 11 may be executed. May be configured such that only the fuel injection in the intake stroke by the second fuel injection valve 12 is executed. In such a configuration, when the SI combustion mode is switched to the HCCI combustion mode, the fuel injection amount in the intake stroke may be corrected to the decrease side as in the embodiment.

  In the embodiment, when the SI combustion mode is switched to the HCCI combustion mode, both the correction to the decrease side of the first fuel injection amount GFOUTP and the correction to the retard side of the second injection timing TINJD are executed. However, only one of these corrections may be executed. Further, in the above case, when the SI combustion mode is switched to the HCCI combustion mode, the ignition timing IGLOG may be corrected to the retard side, or the retard angle correction may not be performed. The spark ignition itself for appropriately controlling the combustion timing may be stopped.

  On the other hand, the embodiment is an example in which the engine water temperature TW is used as the correlation parameter. However, the correlation parameter of the present invention is not limited to this, and the correlation is at least one of the hydraulic oil pressure and the oil temperature. What is necessary is just to have. For example, an oil temperature sensor that detects the hydraulic pressure of the hydraulic oil may be provided, and the oil temperature detected by the oil temperature sensor may be used as the correlation parameter. In that case, in step 49 described above, the HCCI-side switching value CVTECEHM may be calculated by searching the map in accordance with the engine speed NE and the oil temperature. Further, a hydraulic pressure sensor that detects the hydraulic pressure of the hydraulic oil may be provided, and the hydraulic pressure detected by the hydraulic pressure sensor may be used as the correlation parameter. In that case, in step 49 described above, the HCCI-side switching value CVTECEHM may be calculated by searching the map according to the engine speed NE and the hydraulic pressure. Further, both the hydraulic pressure and the oil temperature may be used as the correlation parameter. In this case, in step 49 described above, the map is searched according to the engine speed NE, the hydraulic pressure, and the oil temperature, thereby obtaining the HCCI. What is necessary is just to comprise so that the value CVTTECHM for side switching may be calculated.

  An in-cylinder pressure sensor that detects the pressure in the combustion chamber 3d as an in-cylinder pressure is provided, and the in-cylinder pressure detected by the in-cylinder pressure sensor is used as a combustion state parameter that represents the combustion state of the air-fuel mixture in the combustion chamber 3d. Also good. In that case, in step 49 described above, the HCCI side switching value CVTECEHM may be calculated by searching the map according to the in-cylinder pressure and the engine speed NE. In this case, when the exhaust valve timing is switched from the SI timing to the HCCI timing, the combustion state of the air-fuel mixture in the combustion chamber changes with the switching of the valve timing. It reflects that the timing has actually switched. Therefore, by calculating the HCCI side switching value CVTECEHM according to the in-cylinder pressure representing such a change in the combustion state, it is possible to accurately determine whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing. Can be judged well.

  Further, the embodiment is an example in which a gasoline engine type is used as the internal combustion engine, but the internal combustion engine of the present invention is not limited to this, and the combustion mode is switched between the HCCI combustion mode and the SI combustion mode. Anything that can be driven is acceptable. For example, as an internal combustion engine, a mixture of toluene, dimethyl ether, and other fuels in gasoline may be used, and the mixture is premixed compression ignition combustion without aggressive ignition. However, anything that can be driven is acceptable.

  On the other hand, the embodiment is an example in which the control device of the present invention is applied to an internal combustion engine 3 for a vehicle. However, the control device of the present invention is not limited to this, and is used for a ship internal combustion engine or other industrial equipment. Needless to say, the present invention can also be applied to other internal combustion engines.

  Further, the embodiment is an example in which a hydraulically driven exhaust VT switching mechanism 7 is used as an exhaust valve timing changing device. However, the exhaust valve timing changing device of the present invention is not limited to this, and the exhaust valve timing can be changed. Anything is acceptable. For example, an electric exhaust VT switching mechanism that operates using an electric actuator and / or motor as a drive source may be used as the exhaust valve timing changing device. Further, an exhaust valve timing changing device that changes the phase of the exhaust camshaft relative to the crankshaft may be used.

  Furthermore, in the embodiment, when the count value CKLES2H of the injection correction counter on the horizontal axis is a value 4 as a map for calculating the three values KLES2H, DTINJS2H, and DIGS2H, KLES2H = 1, DTINJS2H = 0, and DIGS2H = 0. However, when the count value CKLES2H of the injection correction counter on the horizontal axis is 5 or more, a map in which KLES2H = 1, DTINJS2H = 0, and DIGS2H = 0 may be used as these calculation maps.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 ECU (1st fuel supply amount calculation means, combustion mode selection means, exhaust valve timing control means, exhaust valve timing switching determination means, first fuel supply amount correction means, correlation parameter detection means, second supply timing Calculation means, second supply timing correction means, ignition timing calculation means, ignition timing correction means)
3 Internal combustion engine 3d Combustion chamber 5 Exhaust valve 7 Exhaust VT switching mechanism (exhaust valve timing changing device)
8a Intake port 11 First fuel injection valve (first fuel supply device)
12 Second fuel injection valve (second fuel supply device)
21 Water temperature sensor (correlation parameter detection means)
GFOUTP First fuel injection amount (first fuel supply amount)
KLES2H Injection amount correction coefficient TINJD Second injection timing (second supply timing)
DTINJS2H Injection timing correction value IGLOG Ignition timing DIGS2H Ignition timing correction value
TW engine water temperature (correlation parameter)

Claims (10)

The combustion mode is configured to be operable by switching between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition, and the exhaust valve timing is changed by the exhaust valve timing changing device. In the internal combustion engine in which the fuel is supplied into the combustion chamber in the intake stroke by the first fuel supply device in the HCCI combustion mode, the exhaust valve timing as the timing is changed, via the exhaust valve timing change device A control device for an internal combustion engine that controls the exhaust valve timing and controls the amount and timing of fuel supplied by the first fuel supply device via the first fuel supply device,
First fuel supply amount calculating means for calculating a first fuel supply amount as a fuel supply amount by the first fuel supply device;
A combustion mode selection means for selecting one of the SI combustion mode and the HCCI combustion mode as the combustion mode;
Based on the selection result of the combustion mode selection means, the exhaust valve timing is controlled to the SI timing when the SI combustion mode is selected, and to the HCCI timing when the HCCI combustion mode is selected. Valve timing control means;
Whether or not the exhaust valve timing has actually switched from the SI timing to the HCCI timing after the combustion mode selected by the combustion mode selection means has switched from the SI combustion mode to the HCCI combustion mode. Exhaust valve timing switching determining means for determining;
Based on the determination result of the exhaust valve timing switching determination means, the calculated first time until a predetermined time elapses from the switching time when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. First fuel supply amount correction means for correcting one fuel supply amount to a decreasing side;
A control device for an internal combustion engine, comprising:   The first fuel supply amount correction means corrects the first fuel supply amount so that the degree of correction to the decrease side becomes smaller as the elapsed time from the switching time becomes longer. The control apparatus for an internal combustion engine according to claim 1. In the internal combustion engine, in the HCCI combustion mode, fuel is supplied into the combustion chamber by the second fuel supply device in the compression stroke,
A second supply time calculating means for calculating a second supply time as a fuel supply time by the second fuel supply device;
Second supply timing correction means for correcting the calculated second supply timing to a more retarded side based on the determination result of the exhaust valve timing switching determination means until the predetermined time elapses from the switching time point; ,
The control apparatus for an internal combustion engine according to claim 1, further comprising:   The second supply time correction means corrects the second supply time so that the degree of correction to the retard side becomes smaller as the elapsed time from the switching time becomes longer. The control apparatus of the internal combustion engine described in 1. The combustion mode is configured to be operable by switching between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition, and the exhaust valve timing is changed by the exhaust valve timing changing device. The exhaust valve timing, which is the timing, is changed, and in the HCCI combustion mode, the fuel is introduced into the combustion chamber in the intake stroke by the first fuel supply device, and the fuel is introduced into the combustion chamber in the compression stroke by the second fuel supply device. In the internal combustion engine to be supplied, the exhaust valve timing is controlled via the exhaust valve timing changing device, and the fuel supply amount and the supply timing by the first fuel supply device are controlled via the first fuel supply device. And controlling the second fuel supply device via the second fuel supply device. A control apparatus for the feed rate and the internal combustion engine for controlling the supply timing of that fuel,
Second supply time calculation means for calculating a second supply time as a fuel supply time by the second fuel supply device;
A combustion mode selection means for selecting one of the SI combustion mode and the HCCI combustion mode as the combustion mode;
Based on the selection result of the combustion mode selection means, the exhaust valve timing is controlled to the SI timing when the SI combustion mode is selected, and to the HCCI timing when the HCCI combustion mode is selected. Valve timing control means;
Whether or not the exhaust valve timing has actually switched from the SI timing to the HCCI timing after the combustion mode selected by the combustion mode selection means has switched from the SI combustion mode to the HCCI combustion mode. Exhaust valve timing switching determining means for determining;
Second supply timing correction means for correcting the calculated second supply timing to a more retarded side until the predetermined time elapses from the switching time based on the determination result of the exhaust valve timing switching determination means; ,
A control device for an internal combustion engine, comprising:   6. The second supply time correction means corrects the second supply time so that the degree of correction to the retard side becomes smaller as the elapsed time from the switching time becomes longer. The control apparatus of the internal combustion engine described in 1. The combustion mode is configured to be operable by switching between an HCCI combustion mode in which the air-fuel mixture is combusted by premixed compression ignition and an SI combustion mode in which the air-fuel mixture is combusted by spark ignition, and the exhaust valve timing is changed by the exhaust valve timing changing device. In the internal combustion engine in which the exhaust valve timing, which is the timing, is changed and the ignition of the air-fuel mixture by the spark plug is also performed in the HCCI combustion mode, the ignition timing of the air-fuel mixture is set via the ignition plug. A control device for an internal combustion engine to control,
Ignition timing calculating means for calculating the ignition timing of the air-fuel mixture by the spark plug;
A combustion mode selection means for selecting one of the SI combustion mode and the HCCI combustion mode as the combustion mode;
Based on the selection result of the combustion mode selection means, the exhaust valve timing is controlled to the SI timing when the SI combustion mode is selected, and to the HCCI timing when the HCCI combustion mode is selected. Valve timing control means;
Whether or not the exhaust valve timing has actually switched from the SI timing to the HCCI timing after the combustion mode selected by the combustion mode selection means has switched from the SI combustion mode to the HCCI combustion mode. Exhaust valve timing switching determining means for determining;
Based on the determination result of the exhaust valve timing switching determination means, the calculated ignition is performed until a predetermined time elapses from a switching time when the exhaust valve timing is actually switched from the SI timing to the HCCI timing. Ignition timing correction means for correcting the timing to the retard side;
A control device for an internal combustion engine, comprising:   The internal combustion engine according to claim 7, wherein the ignition timing correction unit corrects the ignition timing so that the degree of correction to the retard side becomes smaller as the elapsed time from the switching time becomes longer. Engine control device. The exhaust valve timing changing device comprises a hydraulically driven exhaust valve timing changing device driven by hydraulic oil pressure,
A correlation parameter detecting means for detecting a correlation parameter having a correlation with at least one of the hydraulic oil pressure and the oil temperature;
The exhaust valve timing switching determining means determines whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the detected correlation parameter. The control apparatus for an internal combustion engine according to any one of claims 1 to 8. A combustion state parameter detecting means for detecting a combustion state parameter representing a combustion state of the air-fuel mixture in the combustion chamber;
The exhaust valve timing switching determination means determines whether or not the exhaust valve timing is actually switched from the SI timing to the HCCI timing according to the detected combustion state parameter. The control apparatus for an internal combustion engine according to any one of claims 1 to 8.

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