JP5409532B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control apparatus for an internal combustion engine having an HCCI combustion mode and an SI combustion mode as combustion modes, and more particularly to an internal combustion engine control apparatus for switching the combustion mode from the HCCI combustion mode to the SI combustion mode.

  As a conventional control device for this type of internal combustion engine, for example, one disclosed in Patent Document 1 is known. In this control device, in the HCCI combustion mode, the throttle valve is maintained at a predetermined large opening, and the air-fuel ratio of the mixture of fuel and air supplied to the internal combustion engine is controlled to be leaner than the stoichiometric air-fuel ratio. On the other hand, in the SI combustion mode, the throttle valve is controlled to a normal opening smaller than the large opening, and the air-fuel ratio is normally controlled to the stoichiometric air-fuel ratio. Further, when switching from the HCCI combustion mode to the SI combustion mode, the throttle valve is gradually decreased from a large opening to a normal opening. As a result, the output of the internal combustion engine is smoothly reduced while suppressing torque fluctuations associated with switching of the combustion mode.

JP 2000-220458 A

  As described above, in the conventional control device, when the combustion mode is switched to the SI combustion mode, the opening degree of the throttle valve is largely closed from the large opening degree to the normal opening degree. However, even if a control signal for controlling the opening degree of the throttle valve is output, in the subsequent several combustion cycles, there is an operation delay in the actuator that drives the throttle valve or an air supply delay. The pressure of the engine does not drop immediately, and a relatively high pressure may remain. In this case, an air amount exceeding a desired amount is supplied to the internal combustion engine. For this reason, when the fuel supply amount is controlled so that the air-fuel ratio becomes the stoichiometric air-fuel ratio according to the air supply amount, the fuel supply amount increases, thereby temporarily increasing the power of the internal combustion engine. The fluctuations may become large, and there is room for improvement in this respect.

  The present invention has been made to solve such problems, and can appropriately switch the combustion mode from the HCCI combustion mode to the SI combustion mode while suppressing fluctuations in the power of the internal combustion engine. An object of the present invention is to provide a control device for an internal combustion engine.

To achieve the above object, the invention according to claim 1, as a combustion mode ((hereinafter in the embodiment, in this section the same) predetermined value AFL) lean predetermined air-fuel ratio than the stoichiometric air-fuel ratio mixture of A control device 1 for an internal combustion engine 3 having an HCCI combustion mode in which combustion is performed by compression ignition and an SI combustion mode in which an air-fuel mixture having a theoretical air-fuel ratio (predetermined value AFS) is combusted by spark ignition, which is output from the internal combustion engine 3 A transmission 6 for shifting power, a throttle valve 13 provided in the intake passage 9 for adjusting the amount of intake air taken into the internal combustion engine 3, and for switching the combustion mode from the HCCI combustion mode to the SI combustion mode Determination means (ECU 2, step 3 in FIG. 4) for determining whether or not the SI combustion mode switching condition is satisfied, and the SI combustion mode switching condition by the determination means Is determined so that the change in the pressure (intake pressure PB) in the intake passage 9 downstream of the throttle valve 13 associated with the switching to the SI combustion mode is suppressed. By executing gear ratio reduction control for controlling the gear ratio RTRM to a predetermined reduction gear ratio (target gear ratio RTRMCMD), the torque of the internal combustion engine 3 is increased and the opening of the throttle valve 13 is decreased. And a switching time control means (ECU 2, steps 43 and 45 in FIG. 9) for executing throttle valve opening reduction control to be controlled, and the transmission 6 is a continuously variable transmission for shifting the power of the internal combustion engine 3 continuously. Gear ratio change determining means for determining whether or not the gear ratio of the transmission has been changed to a predetermined gear ratio by gear ratio reduction control when it is determined that the SI combustion mode switching condition is satisfied. EC 2, step 64 in FIG. 12 is further provided, and when it is determined that the SI combustion mode switching condition is satisfied, the switching time control means starts the gear ratio reduction control (steps 41 and 61 in FIG. 12). Then, the HCCI combustion mode is continued with the throttle valve 13 kept open (steps 62 and 63 in FIG. 12), and then the gear ratio RTRM of the transmission 6 is set to a predetermined gear ratio by the gear ratio change determining means. If it is determined changed and, (step 64,45 in FIG. 12) to start the throttle valve opening reduction control, (step 44 in FIG. 12) is switched Ru combustion mode to the SI combustion mode it can be characterized.

  According to the control device for an internal combustion engine, when it is determined that the SI combustion mode switching condition for switching the combustion mode from the HCCI combustion mode to the SI combustion mode is satisfied, the inside of the intake passage accompanying the switching to the SI combustion mode is established. In order to suppress the change in the pressure of the transmission, the transmission ratio reduction control for controlling the transmission gear ratio to a predetermined reduction gear ratio is executed, and the throttle valve opening for controlling the throttle valve opening to the reduction side is executed. The degree reduction control is executed.

  When the transmission gear ratio is controlled to be reduced as described above, when the power of the internal combustion engine is constant, the rotational speed of the internal combustion engine decreases and the torque increases, which increases the torque of the internal combustion engine. Accordingly, the amount of air supplied to the internal combustion engine can be increased. For this reason, compared with the case where the gear ratio is not changed, the amount of decrease in the throttle valve opening from the HCCI combustion mode by the throttle valve opening reduction control can be reduced, and the switching time of the throttle valve is shortened accordingly. Become. As described above, the amount of decrease in the opening of the throttle valve and the switching time are reduced, so that the pressure and the remaining time remaining in the intake passage at the time of switching can be reduced, thereby avoiding a large increase in air. it can. For this reason, when the combustion mode is switched to the SI combustion mode, the fuel supply amount greatly increases even when the fuel supply amount is controlled so as to obtain a predetermined air-fuel ratio according to the air supply amount. Therefore, it is possible to appropriately switch to the SI combustion mode while suppressing fluctuations in the power of the internal combustion engine.

Further , according to this configuration, the transmission is configured by a continuously variable transmission that continuously changes the power of the internal combustion engine. In general, such a continuously variable transmission does not use a clutch or the like to set a gear ratio, unlike a stepped transmission, and therefore, after the start of the gear ratio changing operation, the gear ratio is changed to the target gear ratio. It takes a relatively long time to complete. Therefore, if the gear ratio reduction control and the throttle valve opening reduction control are started at the same time, the throttle of the internal combustion engine cannot be increased to the torque after completion of the change during the change to the predetermined reduction gear ratio. When the valve is controlled to decrease, air is excessively supplied to the internal combustion engine, and the power of the internal combustion engine is likely to fluctuate greatly.

According to the present invention, when it is determined that the SI combustion mode switching condition is satisfied, the gear ratio reduction control is started , and the HCCI combustion mode is continued while the throttle valve opening is maintained. Thereafter, when the speed ratio of the continuously variable transmission is determined to have been changed to a predetermined gear ratio, to start the throttle valve opening reduction control, Ru switching combustion mode to the SI combustion mode. Therefore, since the change of the gear ratio by the continuously variable transmission is finished and the control of the throttle valve is started in the state where the torque of the internal combustion engine has increased to the torque after the change is finished, the gear ratio is being changed. The fluctuation of the power of the internal combustion engine in can be suppressed.

The invention according to claim 2, in the control apparatus for an internal combustion engine according to claim 1, switching control means, when the SI combustion mode switching condition is determined to be satisfied, the throttle valve opening reduction control by the execution, and controlling the air-fuel ratio of the mixed Aiki from the predetermined air-fuel ratio sense Ronsora ratio.

  According to this configuration, when it is determined that the SI combustion mode switching condition is satisfied, the throttle valve opening reduction control is executed, so that the air-fuel ratio of the air-fuel mixture is changed from the lean side to the stoichiometric air-fuel ratio. To control. Therefore, by performing the throttle valve opening reduction control and the gear ratio reduction control in combination, the above-described advantage according to claim 1 can be effectively obtained.

It is a figure showing roughly a hybrid vehicle carrying an internal combustion engine to which a control device in an embodiment of the present invention is applied. FIG. 2 is a diagram schematically showing the internal combustion engine of FIG. 1. It is a figure which shows the valve lift curve of the intake valve obtained by the intake side valve mechanism, and the valve lift curve of the exhaust valve obtained by the exhaust side valve mechanism. It is a main flow which shows a combustion control process. It is a subroutine which shows the setting process of the HCCI combustion flag. It is an example of the map used by the process of FIG. It is a subroutine which shows HCCI combustion control processing. It is a subroutine which shows SI combustion control processing. It is a subroutine which shows the control processing at the time of switching at the time of switching combustion mode from HCCI combustion mode to SI combustion mode in a 1st embodiment of the present invention. In 1st Embodiment of this invention, when switching combustion mode from HCCI combustion mode to SI combustion mode, it is a figure which shows the operation example at the time of changing a gear ratio. It is a figure which shows the operation example when not changing a gear ratio when switching a combustion mode from HCCI combustion mode to SI combustion mode. It is a subroutine which shows the control process at the time of switching at the time of switching combustion mode from HCCI combustion mode to SI combustion mode in 2nd Embodiment of this invention. In 2nd Embodiment of this invention, when switching a combustion mode from HCCI combustion mode to SI combustion mode, it is a figure which shows the operation example at the time of changing a gear ratio.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, an internal combustion engine (hereinafter referred to as “engine”) 3 to which a control device 1 according to an embodiment of the present invention is applied includes a power source for a hybrid vehicle (hereinafter referred to as “vehicle”) V together with an electric motor 4. It is installed as.

  In this vehicle V, the crankshaft 3a of the engine 3 is directly connected to the rotating shaft of the electric motor 4, and the electric motor 4 is connected to the left and right drive wheels via the clutch 5, the transmission 6, the differential gear mechanism 7, and the like. 8 and 8 are connected. The clutch 5 is of an electromagnetic clutch type, and its engaged / disengaged state is controlled by a control input from the ECU 2 described later.

  The engine 3 is a gasoline engine and has, for example, four cylinders C (only one is shown in FIG. 2). As shown in FIG. 2, an intake passage 9 and an exhaust passage 10 are connected to the cylinder head 3 b of the engine 3, and a fuel injection valve (hereinafter referred to as “injector”) 11 and a spark plug 12 (both refer to FIG. 1). Is attached to face the combustion chamber 3c. The fuel injection amount QINJ injected from the injector 11 is controlled by a control input from the ECU 2. The ignition timing of the spark plug 12 is also controlled by a control input from the ECU 2.

  In the engine 3, as a combustion mode, a compression ignition combustion mode (hereinafter, referred to as “HCCI combustion mode”) in which an air-fuel mixture including fuel injected from the injector 11 is combusted by self-ignition, and spark ignition by the spark plug 12. The spark ignition combustion mode (hereinafter referred to as “SI combustion mode”) for combustion by the ECU 2 is controlled by the ECU 2.

  The electric motor 4 is configured by a brushless DC motor, and is connected to the ECU 2 and the battery 16 via the PDU 15. The PDU 15 is configured by an electric circuit including an inverter and the like. The ECU 2 controls power transfer between the electric motor 4 and the battery 16 via the PDU 15. Specifically, the output of the electric motor 4 is controlled while the vehicle V is accelerating, and the power regeneration by the electric motor 4 is controlled while the vehicle V is decelerating.

  A crank angle sensor 21 is provided on the crankshaft 3 a of the engine 3. The crank angle sensor 21 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3a rotates.

  The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. Further, the TDC signal is a signal indicating that in any cylinder C, the piston 3d is at a predetermined crank angle position slightly before the top dead center at the start of the intake stroke, as in the present embodiment. When the engine 3 has four cylinders, it is output every crank angle of 180 °.

  The transmission 6 is a gear-type stepped transmission that changes the power output from the engine 3 stepwise. Specifically, the transmission 6 includes an input shaft and an output shaft 6a, a plurality of gear trains having different gear ratios, and a space between the plurality of gear trains and the input shaft and the output shaft 6a for each gear train. The clutch includes a clutch (not shown) that is connected and disconnected, and has first to fifth forward speeds and one reverse speed. These shift speeds are switched by a control input from the ECU 2, thereby changing the gear ratio.

  An output shaft rotational speed sensor 22 is provided on the output shaft 6 a of the transmission 6. The output shaft rotational speed sensor 22 detects the rotational speed (hereinafter referred to as “output shaft rotational speed”) NOUT of the output shaft 6 a and outputs a detection signal to the ECU 2. The ECU 2 calculates the speed ratio RTRM set in the transmission 6 based on the output shaft speed NOUT and the engine speed NE.

  Each cylinder C is provided with a pair of intake valves 14, 14 (only one shown) and a pair of exhaust valves 15, 15 (only one shown). The intake valve 14 is opened and closed by an intake side valve mechanism 40, and the exhaust valve 15 is opened and closed by an exhaust side valve mechanism 50.

  The intake side valve mechanism 40 is of a normal cam drive type, and includes a rotatable intake camshaft 41, an intake cam 42 provided integrally with the intake camshaft 41, a rocker arm shaft 43, and a rocker arm shaft 43. And two rocker arms 44 that are in contact with the upper ends of the intake valves 14 and 14 respectively.

  The intake camshaft 41 is connected to the crankshaft 3a via an intake sprocket and a timing chain (both not shown), and rotates once for every two rotations of the crankshaft 3a. When the intake camshaft 41 rotates, the rocker arm 44 is pressed by the intake cam 42, rotates around the rocker arm shaft 43, and presses the intake valves 14, 14, thereby opening and closing the intake valves 14,14.

  The exhaust side valve mechanism 50 is for changing the lift of the exhaust valves 15 and 15 in two stages, and includes an exhaust camshaft 51, an exhaust cam 52, an exhaust lift variable mechanism 53, and the like.

  The exhaust camshaft 51 is connected to the crankshaft 3a via an exhaust sprocket and a timing chain (both not shown), and rotates once every time the crankshaft 3a rotates twice.

  The exhaust cam 52 is provided integrally with the exhaust camshaft 51, has two low speed cams (only one shown) provided for each cylinder C, and is provided for each cylinder C and has a cam nose higher than the low speed cam. It has a single high-speed cam (not shown).

  The variable exhaust lift mechanism 53 switches the lift of the exhaust valve 15 (hereinafter referred to as “exhaust lift”) to a predetermined low lift or high lift. The configuration is the same as that already proposed by the present applicant in Japanese Patent Laid-Open No. 2000-227013, and the outline thereof will be briefly described below.

  The variable exhaust lift mechanism 53 includes a rocker arm shaft 54, two low-speed rocker arms 55, 55 (only one is shown) and a high-speed rocker arm (not shown) that are rotatably attached to the cylinder C. And an electromagnetic valve 56 (see FIG. 2) connected to the ECU 2. The low-speed rocker arms 55 and 55 are in contact with the exhaust valves 15 and 15 of each cylinder C, respectively.

  The lift mode of the variable exhaust lift mechanism 53 is switched between the low lift mode and the high lift mode by controlling the electromagnetic valve 56 by a control input from the ECU 2. In this low lift mode, when the exhaust camshaft 51 rotates, the low-speed rocker arm 55 is driven by the low-speed cam 52 and the high-speed rocker arm is driven by the high-speed cam. Rotate around. Accordingly, each exhaust valve 15 is driven to open and close by the low-speed rocker arm 55, and opens and closes with a predetermined low lift and a predetermined valve opening time.

  On the other hand, in the high lift mode, the high-speed rocker arm is integrally connected to the low-speed rocker arms 55 and 55, and when the exhaust camshaft 51 rotates, the high-speed rocker arm driven by the high-speed cam rotates and the low-speed rocker arm 55 integrally therewith. Rotate. As a result, the exhaust valve 15 is driven to open and close by the high-speed rocker arm via the low-speed rocker arm 55, so that the lift becomes higher than that in the low lift mode (high lift). Further, in the high lift mode, the valve opening period of the exhaust valve 15 becomes longer than in the low lift mode, and the valve opening timing shifts to the advance side (see FIG. 3A). The lift mode of the variable exhaust lift mechanism 53 is set to the low lift mode in the above-described HCCI combustion mode, and is set to the high lift mode in the SI combustion mode.

  With the above configuration, in the SI combustion mode, the intake valve 14 is opened before the high lift exhaust valve 15 is closed (FIG. 3A). On the other hand, in the HCCI combustion mode, the intake valve 14 is opened after the low lift exhaust valve 15 is completely closed ((b) in the figure), so that the internal EGR that causes the exhaust gas to remain in the cylinder C is reduced. can get. Thereby, HCCI combustion is accelerated | stimulated by raising the temperature in the cylinder C with waste gas.

  In the intake passage 9, a throttle valve 13, an intake pressure sensor 23, and an air flow sensor 24 are provided in order from the upstream side. The opening degree of the throttle valve 13 is controlled via a TH actuator 13a by a control input from the ECU 2, and thereby the amount of intake air passing through the throttle valve 13 is controlled.

  The intake pressure sensor 23 detects a pressure (hereinafter referred to as “intake pressure”) PB in the intake passage 9 and outputs a detection signal to the ECU 2. The air flow sensor 24 detects an intake air amount QA taken into the engine 3 and outputs a detection signal to the ECU 2.

  A LAF sensor 25 is provided in the exhaust passage 10. The LAF sensor 25 linearly detects the oxygen concentration in the exhaust gas flowing through the exhaust passage 10 in a wide range of air-fuel ratios from a rich region richer than the stoichiometric air-fuel ratio to the extreme lean, and sends the detection signal to the ECU 2. Output. The ECU 2 calculates the air-fuel ratio AF of the air-fuel mixture based on the detection signal from the LAF sensor 25.

  In addition, a detection signal representing the depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle V is transmitted from the vehicle speed sensor 27 to the ECU 2 from the accelerator opening sensor 26. Each detection signal is output.

  The ECU 2 is composed of a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the like. The ECU 2 determines the operating state of the engine 3 according to the detection signals of the various sensors 21 to 27 described above, and sets the combustion mode of the engine 3 to the SI combustion mode or the HCCI combustion according to the determined operating state. Determine the mode. Further, the ECU 2 executes a combustion control process for controlling the combustion state of the engine 3 according to the determined combustion mode. In the present embodiment, the ECU 2 corresponds to a determination unit and a switching time control unit.

  FIG. 4 is a flowchart showing the combustion control process described above. This process is executed in synchronization with the generation of the TDC signal. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the HCCI combustion flag F_HCCI is “1”.

  FIG. 5 is a subroutine showing the setting process of the HCCI combustion flag F_HCCI. In this process, first, in step 11, it is determined whether or not the engine 3 is in an operation region in which HCCI combustion is to be performed (hereinafter referred to as “HCCI region”). This determination is made according to the engine speed NE and the required torque PMCMD based on the map shown in FIG. In this map, the HCCI region is set to an operation region in which the engine speed NE is in the low to medium rotation region and the required torque PMCMD is in the low to medium load region. The required torque PMCMD is calculated according to the engine speed NE and the accelerator pedal opening AP.

  If the determination result in step 11 is YES and the engine 3 is in the HCCI region, it is assumed that the condition for performing combustion in the HCCI combustion mode is satisfied, and the HCCI combustion flag F_HCCI is set to “1” in order to express that fact. ”(Step 12), and the process ends. On the other hand, if the determination result in step 11 is NO and the engine 3 is not in the HCCI region, the HCCI combustion flag F_HCCI is set to “0” (step 13), and this process is terminated.

  Returning to FIG. 4, when the determination result of step 1 is YES and the HCCI combustion flag F_HCCI is “1”, HCCI combustion control is executed (step 2), and this process is terminated.

  FIG. 7 shows a subroutine of this HCCI combustion control process. In this process, first, in step 21, the transmission gear ratio RTRM of the transmission 6 is controlled. Specifically, a target gear ratio RTRMCMD of the transmission 6 is calculated according to the engine speed NE and the vehicle speed VP, and a control input is calculated according to the target gear ratio RTRMCMD and the gear ratio RTRM. Then, the gear ratio RTRM is controlled by controlling the gear position of the transmission 6 by this control input.

  Next, the lift mode is set to the low lift mode, and the exhaust valve 15 is driven with a low lift (step 22). Next, the throttle valve 13 is controlled to be fully opened (step 23). Next, the fuel injection amount QINJ is calculated according to the target air-fuel ratio AFCMD and the intake air amount QA (step 24), and this process is terminated. The target air-fuel ratio AFCMD at this time is set to a predetermined value AFL that is leaner than the theoretical air-fuel ratio.

  Returning to FIG. 4, when the determination result of step 1 is NO and the HCCI combustion flag F_HCCI is “0”, whether or not the HCCI combustion flag F_HCCI has changed from “1” to “0” between the previous time and the current time. Is discriminated (step 3). When the determination result is YES and the determined combustion mode is immediately after switching from the HCCI combustion mode to the SI combustion mode, the value TM of the up-count type switching timer (hereinafter referred to as “switching timer value”) TM is set to the value 0. After setting (step 7), control at the time of switching described later is executed (step 8), and this process is terminated.

  On the other hand, when the determination result in step 3 is NO, it is determined whether or not the switching timer value TM is equal to or longer than a predetermined time TMREF (for example, 1.5 sec) (step 4). When the determination result is NO, that is, when the predetermined combustion time TMREF has not elapsed after the determined combustion mode is switched from the HCCI combustion mode to the SI combustion mode, the process proceeds to step 8 and the switching control is continued. Run.

  If the determination result in step 4 is YES and TM ≧ TMREF, the switching flag F_SW is set to “0” (step 5), then SI combustion control is executed (step 6), and this process ends.

  FIG. 8 shows a subroutine of this SI combustion control process. In this process, first, in step 31, as in step 21, the gear ratio RTRM of the transmission 6 is controlled in accordance with the engine speed NE and the required torque PMCMD.

  Next, the lift mode is set to the high lift mode, and the exhaust valve 15 is driven with a high lift (step 32). Next, the opening degree of the throttle valve 13 is controlled (step 33). Specifically, the target value of the throttle valve 13 is calculated according to the accelerator pedal opening AP, and the throttle valve 13 is controlled by controlling the TH actuator 13a according to this target value. The

  Next, the fuel injection amount QINJ is calculated according to the target air-fuel ratio AFCMD and the intake air amount QA (step 34), and this process is terminated. The target air-fuel ratio AFCMD at this time is set to a predetermined value AFS corresponding to the theoretical air-fuel ratio.

  FIG. 9 shows a subroutine for the control process at the time of switching executed in the step 8. In this process, first, in step 41, it is determined whether or not the switching flag F_SW is “1”. In the first loop in which the control at the time of switching is started, the determination result of step 41 becomes NO by the execution of step 5, and in this case, the switching flag F_SW is set to “1” (step 42) and the speed change is performed. The gear ratio RTRM is controlled to be decreased by shifting up the gear stage of the machine 6 by one stage (step 43).

  On the other hand, in the second and subsequent loops in which the control at the time of switching is started, the determination result in Step 41 becomes YES by executing Step 42, and in this case, the shifted gear stage is held (Step 47). ).

  In step 44 following step 43 or 47, the lift mode is set to the high lift mode, and the exhaust valve 15 is driven with a high lift. Next, similarly to the step 33, the throttle valve 13 is controlled from the fully open state to the decreasing side by controlling the opening degree of the throttle valve 13 according to the accelerator opening degree AP (step 45). Next, as in step 34, the fuel injection amount QINJ is calculated in accordance with the target air-fuel ratio AFCMD and the intake air amount QA (step 46), and this process ends.

  FIG. 10 shows an operation example obtained by the combustion control process described so far. In this example, the combustion mode is set to the HCCI combustion mode before the timing t0. As a result, the throttle valve 13 is controlled to be fully open, and the target air-fuel ratio AFCMD is set to a predetermined value AFL that is leaner than the stoichiometric air-fuel ratio. Further, the gear stage of the transmission 6 at this time is set to the third stage.

  From this state, when the combustion mode is switched to the SI combustion mode at timing t0, the gear stage of the transmission 6 is shifted up from the third stage to the fourth stage (step 43 in FIG. 9) and the throttle valve 13 Is controlled to decrease (step 45). At this time, the exhaust valve 15 is switched from the low lift to the high lift (step 44), and the target air-fuel ratio AFCMD is set to a predetermined value AFS corresponding to the stoichiometric air-fuel ratio.

  As the transmission 6 shifts up, the engine speed NE decreases and the engine torque increases. Therefore, the amount of air supplied to the engine 3 can be increased as the engine torque increases. For this reason, compared with the case where the gear ratio RTRM is not changed as shown in FIG. 11, the amount of decrease in the opening degree of the throttle valve 13 is reduced, and the switching time of the throttle valve 13 is accordingly shortened. As described above, the amount of decrease in the opening degree of the throttle valve 13 and the switching time are reduced, so that the intake pressure PB and the remaining time remaining in the intake passage 9 at the time of switching can be reduced. Can be avoided from greatly increasing. Further, since the target air-fuel ratio AFCMD controls the fuel injection amount QINJ so that the predetermined value AFS corresponding to the theoretical air-fuel ratio is obtained according to the intake air amount QA, the fuel injection amount QINJ does not increase greatly. Therefore, it is possible to appropriately switch to the SI combustion mode while suppressing fluctuations in the power of the engine 3.

  In addition, since the gear position of the transmission 6 is set using a clutch, the change of the gear ratio RTRM to the target gear ratio is completed in a relatively short time after the start of the operation of changing the gear ratio RTRM. Accordingly, when the SI combustion mode is switched, the transmission 6 is shifted up and the throttle valve 13 is controlled to decrease the opening degree simultaneously (steps 43 and 45 in FIG. 9), so that excess air is passed. It is possible to switch to the SI combustion mode in a short time while supplying the fuel without any shortage and suppressing fluctuations in the power of the engine 3.

  Further, when the mode is switched to the SI combustion mode, the target air-fuel ratio AFCMD is set from the predetermined value AFL on the lean side to the predetermined value AFS corresponding to the theoretical air-fuel ratio, and the throttle valve 13 is controlled to the decreasing side, The air-fuel ratio AF is controlled to the stoichiometric air-fuel ratio. Therefore, by performing the reduction side control of the throttle valve 13 and the transmission 6 upshifting together, the above-described advantages can be effectively obtained.

  Next, a second embodiment of the present invention will be described. The second embodiment is different from the first embodiment described above only in the configuration of the transmission 6 and is the same in other configurations on hardware. The transmission 6 is a belt-type continuously variable transmission that continuously changes the power output from the engine 3. Specifically, the transmission 6 includes a drive pulley, a driven pulley, and a belt (not shown) that is wound around both pulleys and transmits the former power to the latter. The transmission gear ratio RTRM of the transmission 6 is controlled by controlling a CVT actuator (not shown) by a control input from the ECU 2 to drive one pulley steplessly by hydraulic pressure and changing the effective diameter of both pulleys. ,Be changed.

  Further, in the present embodiment, as in the first embodiment, the combustion control process is executed, and only a part of the execution contents of the switching time control is different from the first embodiment. Therefore, in FIG. 12 showing the control process at the time of switching in this embodiment, the same execution number as the control process at the time of switching in the first embodiment shown in FIG. Will be described. In the present embodiment, the ECU 2 corresponds to determination means, switching time control means, and gear ratio change determination means.

  In this process, first, in step 41, it is determined whether or not the switching flag F_SW is “1”. When the determination result is NO and the first loop in which the control at the time of switching is started, the switching flag F_SW is set to “1” (step 42), and the transmission gear ratio RTRM of the transmission 6 is controlled to the decreasing side (step). 61). Specifically, a target speed ratio RTRMCMD smaller than that in the HCCI combustion mode is set, and the CVT actuator is driven so that the speed ratio RTRM becomes the target speed ratio RTRMCMD.

  Next, the lift mode is set to the low lift mode, the exhaust valve 15 is continuously driven with a low lift (step 62), and the throttle valve 13 is controlled to be fully opened (step 63).

  On the other hand, when the determination result in step 41 is YES, it is determined whether or not the detected gear ratio RTRM is equal to or less than the target gear ratio RTRMCMD (step 64). When the determination result is NO and RTRM> RTRMCMD, it is determined that the change of the transmission gear ratio RTRM to the target transmission gear ratio RTRMCMD has not been completed, and the process proceeds to step 62 and subsequent steps, and the exhaust valve 15 is continuously driven with a low lift. The throttle valve 13 is controlled to be fully opened.

  If the determination result in step 64 is YES and the gear ratio RTRM ≦ target gear ratio RTRMCMD, the lift mode is set to the high lift mode and the exhaust valve 15 is driven at a high lift (step 44), and the accelerator opening The opening degree of the throttle valve 13 is controlled according to AP (step 45).

  In step 46 following step 45 or 63, the fuel injection amount QINJ is calculated according to the target air-fuel ratio AFCMD and the intake air amount QA, and this process is terminated.

  FIG. 13 shows an operation example obtained by the combustion control process according to the second embodiment described so far. In this example, before the timing t0, the combustion mode is set to the HCCI combustion mode, and accordingly, the throttle valve 13 is controlled to the fully open state, and the target air-fuel ratio AFCMD is a predetermined value that is leaner than the stoichiometric air-fuel ratio. It is set to the value AFL.

  From this state, when the combustion mode is switched to the SI combustion mode at timing t0, the transmission gear ratio RTRM of the transmission 6 is controlled to the target transmission gear ratio RTRMCMD on the decreasing side (step 61 in FIG. 12). At this time, until the gear ratio RTRM is changed to the target gear ratio RTRMCMD (t0 to t1), the exhaust valve 15 is maintained at a low lift (step 62), and the throttle valve 13 is controlled to be fully opened (step 62). At the same time as step 63), the ignition by the spark plug 12 is stopped. As described above, HCCI combustion is continuously performed until the change of the gear ratio RTRM to the target gear ratio RTRMCMD is completed.

  Thereafter, when the gear ratio RTRM reaches the target gear ratio RTRMCMD and the change to the target gear ratio RTRMCMD is completed (t1), the exhaust valve 15 is driven at a high lift (step 44) and the opening of the throttle valve 13 Is controlled to decrease (step 45). Further, ignition by the spark plug 12 is executed, and SI combustion is performed.

  As described above, the transmission 6 of the present embodiment is configured by a belt-type continuously variable transmission, and the setting of the transmission gear ratio RTRM is performed by driving the pulley continuously. After the change operation is started, it takes a relatively long time to complete the change of the speed ratio RTRM to the target speed ratio RTRMCMD. Therefore, according to the present embodiment, when the HCCI combustion flag F_HCCI is switched from “1” to “0”, the control to the target gear ratio RTRMCMD on the reduction side of the gear ratio RTRM is started, and then the gear shift is performed. When the ratio RTRM reaches the target gear ratio RTRMCMD, the opening degree of the throttle valve 13 is controlled to the decreasing side. Therefore, since the change of the transmission gear ratio RTRM by the transmission 6 is completed and the torque of the engine 3 has increased to the torque after the completion of the change of the transmission gear ratio RTRM, the control to the decrease side of the throttle valve 13 is started. Variations in the power of the engine 3 during the change of the transmission gear ratio RTRM can be suppressed.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the first embodiment, as the gear ratio reduction control for controlling the gear ratio to the decreasing side, the gear stage of the transmission 6 is shifted up by only one stage. May be.

  In the second embodiment, whether or not the change of the transmission gear ratio RTRM has been completed is determined based on the comparison result between the detected transmission gear ratio RTRM and the target transmission gear ratio RTRMCMD, but is not limited thereto. Alternatively, it may be performed based on the elapsed time from the start of the speed change operation.

  Further, the embodiment is an example in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to various engines such as a diesel engine other than a gasoline engine. Also, the present invention can be applied to engines other than those for vehicles, for example, engines for marine propulsion devices such as outboard motors having a crankshaft arranged vertically. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Control apparatus 2 ECU (determination means, switching time control means, and gear ratio change determination means)
3 Engine 6 Transmission 9 Air intake passage 13 Throttle valve
PB intake pressure (pressure in intake passage)
RTRMCMD target gear ratio (predetermined gear ratio)

Claims (2)

A control apparatus for an internal combustion engine having an HCCI combustion mode in which an air-fuel mixture having a predetermined air-fuel ratio leaner than the stoichiometric air-fuel ratio is combusted by compression ignition, and an SI combustion mode in which the air-fuel mixture having the stoichiometric air-fuel ratio is combusted by spark ignition. Because
A transmission for shifting the power output from the internal combustion engine;
A throttle valve provided in an intake passage for adjusting the amount of intake air taken into the internal combustion engine;
Determining means for determining whether an SI combustion mode switching condition for switching the combustion mode from the HCCI combustion mode to the SI combustion mode is satisfied;
When it is determined by the determination means that the SI combustion mode switching condition is satisfied, a change in pressure in the intake passage downstream of the throttle valve accompanying switching to the SI combustion mode is suppressed. Further, by executing gear ratio reduction control for controlling the gear ratio of the transmission to a predetermined gear ratio on the reduction side, the torque of the internal combustion engine is increased and the opening of the throttle valve is controlled to the reduction side. Switching time control means for executing throttle valve opening reduction control to perform ,
The transmission is composed of a continuously variable transmission that continuously changes the power of the internal combustion engine,
Gear ratio change determining means for determining whether or not the gear ratio of the transmission has been changed to the predetermined gear ratio by the gear ratio reduction control when it is determined that the SI combustion mode switching condition is satisfied; In addition,
When it is determined that the SI combustion mode switching condition is satisfied, the switching time control means starts the gear ratio reduction control and continues the HCCI combustion mode while maintaining the opening degree of the throttle valve. Thereafter, when the gear ratio change determining means determines that the gear ratio of the transmission has been changed to the predetermined gear ratio, the throttle valve opening reduction control is started, and the combustion mode is set. control apparatus for an internal combustion engine, characterized in Rukoto switched to the SI combustion mode. The switching time control means executes the throttle valve opening reduction control when it is determined that the SI combustion mode switching condition is satisfied, thereby changing the air-fuel ratio of the air-fuel mixture from the predetermined air-fuel ratio to the stoichiometric air-fuel ratio. and controlling the control apparatus for an internal combustion engine according to claim 1.

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