JP5364636B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that burns an air-fuel mixture supplied into a cylinder by compression ignition.

  As a control device for a conventional internal combustion engine, for example, one disclosed in Patent Document 1 is known. This internal combustion engine is of a premixed compression ignition type in which an air-fuel mixture supplied into a cylinder is combusted by compression ignition, and is provided in an intake passage, and includes a heat exchanger for heating intake air, an intake valve and an exhaust valve. And a variable valve mechanism that changes the opening / closing timing independently of each other. In this control device, it is determined whether or not the temperature of the air-fuel mixture in the cylinder is within a range where compression ignition is possible by searching a predetermined map according to the load and the rotational speed of the internal combustion engine. When the temperature of the mixture is not within the range where compression ignition is possible, the temperature of the mixture is within the range where compression ignition is possible by heating the intake air with a heat exchanger or changing the internal EGR amount with a variable valve mechanism. Adjust to.

  Moreover, what was disclosed by patent document 2 is known as another conventional internal combustion engine control apparatus. This internal combustion engine includes a variable valve mechanism that changes a lift and a valve opening period of an intake valve by switching an intake cam that drives the intake valve to a high-speed cam and a low-speed cam. In this control device, when the intake cam is switched from the low speed cam to the high speed cam, the fuel injection amount is decreased by a predetermined ratio. As a result, by making the air-fuel ratio lean and correcting the engine torque, a rapid increase in torque accompanying switching from the low speed cam to the high speed cam is suppressed. On the other hand, when the intake cam is switched from the high speed cam to the low speed cam, the fuel injection amount is increased by a predetermined rate. As a result, the air-fuel ratio is enriched and the engine torque is increased, thereby suppressing a rapid decrease in torque accompanying switching from the high speed cam to the low speed cam. Further, the increase or decrease of the fuel injection amount at the time of switching of the intake cam as described above is performed when a predetermined time corresponding to the time required for switching of the intake cam has elapsed after the switching command is output. It is set according to the temperature of the cooling water and the intake air of the internal combustion engine.

JP 2005-320948 A JP-A-7-233744

  However, in the control device of Patent Document 1, since there is a delay in the heating of the intake air by the heat exchanger and the change in the internal EGR amount by the variable valve mechanism, the temperature of the air-fuel mixture is not adjusted until the temperature adjustment of the air-fuel mixture is completed. May deviate from the temperature range in which compression ignition is possible, in which case misfire and knocking are likely to occur, and stable combustion cannot be ensured. In particular, when the required torque changes greatly, the occurrence period of such a problem becomes long.

  Further, in the control device of Patent Document 2, although the operation delay of the intake cam switching mechanism is taken into consideration, the fuel injection amount is set until a predetermined time elapses after the intake cam switching command is output. It is held at the value when the switching command is output. For this reason, for example, when this control method is applied to the control of the internal EGR amount when the required torque increases in a compression ignition type internal combustion engine, and the intake cam is switched, the switching command is output. Until the predetermined time elapses, the fuel injection amount is held at the value at the time of output of the switching command, so the compression end temperature of the internal combustion engine cannot be controlled appropriately, and stable combustion is ensured. I can't. Furthermore, since the fuel injection amount changes abruptly when a predetermined time has elapsed, the output of the internal combustion engine fluctuates abruptly and drivability deteriorates.

  The present invention has been made to solve the above-described problems, and controls an internal combustion engine that can ensure stable combustion by compression ignition in each combustion cycle even when the required torque greatly changes. An object is to provide an apparatus.

  In order to achieve the above object, the invention according to claim 1 is based on the operation amount (cam phase CAEX) of the variable valve operating apparatus (cam phase variable mechanism 10 in the embodiment (hereinafter the same in this section)). By changing the operating characteristic (opening / closing timing) of the engine valve (exhaust valve 9) that is at least one of the intake valve and the exhaust valve, the internal EGR that causes the burned gas to remain in the cylinder 3a is controlled, and the inside of the cylinder 3a A required torque calculating means (ECU 2, step 3 in FIG. 4) for calculating a required torque BMEP required for the internal combustion engine 3. Fuel injection amount calculation means (ECU 2, FIG. 6) for calculating the fuel injection amount QINJ to be supplied from the fuel injection valve 4 to the cylinder 3a according to the calculated required torque, and compression ignition Target compression end temperature setting means (ECU 2, step 1 in FIG. 4) for setting a target compression end temperature T_TDCCMD that is a target of the compression end temperature T_TDC at the time of combustion, and the target compression according to the calculated required torque BMEP Target operating amount setting means (ECU2, FIG. 4) for setting a target operating amount (target cam phase CAEXCMD) that is a target of the operating amount of the variable valve gear corresponding to the internal EGR amount so that the end temperature T_TDCCMD is obtained; Next operation amount estimation means (ECU2, steps 13, 14 in FIG. 6) for estimating the next operation amount (next phase CAEX (k + 1)) of the variable valve gear in the next combustion cycle according to the set target operation amount. FIG. 7), and the compression end temperature T_TDC in the next combustion cycle becomes the target compression end temperature T_TDCCM according to the estimated next operation amount. So that the required torque correcting means for correcting the required torque BMEP used for calculating the fuel injection amount QINJ (ECU 2, step 15 of FIG. 6, FIG. 8), characterized in that it comprises a, a.

  According to this internal combustion engine, the operating characteristics of the engine valve are changed in accordance with the operation amount of the variable valve operating device, thereby controlling the internal EGR that causes the burned gas to remain in the cylinder. Further, the air-fuel mixture supplied into the cylinder is burned by compression ignition. Further, according to this control device, the fuel injection amount is calculated according to the calculated required torque. Further, the target operating amount of the variable valve operating apparatus corresponding to the internal EGR amount that can obtain the target compression end temperature is set according to the required torque, and in the next combustion cycle according to the set target operating amount. Estimate the next operation amount of the variable valve gear. Then, according to the estimated next operation amount, the required torque used for calculating the fuel injection amount is corrected so that the compression end temperature in the next combustion cycle becomes the target compression end temperature.

  When the required torque changes, the internal EGR amount may be changed in order to keep the compression end temperature in the cylinder at the target compression end temperature. For example, when the required torque increases, the amount of air-fuel mixture supplied into the cylinder increases, and the combustion energy generated in the cylinder increases accordingly, so the temperature of burned gas increases. For this reason, in order to keep the compression end temperature in the cylinder at the target compression end temperature, it is necessary to reduce the internal EGR amount. However, since the operation of the variable valve system that controls the internal EGR amount involves an inevitable response delay, when the required torque changes greatly, the internal EGR amount is controlled to the internal EGR amount according to the required torque until the next combustion cycle. I can't. According to the present invention, the next operation amount of the variable valve operating apparatus in the next combustion cycle is estimated, and the compression end temperature in the next combustion cycle becomes the target compression end temperature in accordance with the estimated next operation amount. The required torque used for calculating the fuel injection amount is corrected. As a result, even when the required torque changes greatly, in each combustion cycle, the compression end temperature can be accurately controlled to the target compression end temperature, so that the air-fuel mixture supplied into the cylinder is stably combusted by compression ignition. Can be made.

  According to a second aspect of the present invention, in the control apparatus 1 for an internal combustion engine according to the first aspect, the burnt gas temperature obtaining means (ECU 2, step 4 in FIG. 4) for obtaining the burned gas temperature TEX in the current combustion cycle ), And the target operation amount setting means sets the target operation amount of the variable valve operating apparatus in accordance with the acquired temperature TEX of the burned gas (steps 5 and 6 in FIG. 4). .

  According to this configuration, in each combustion cycle, the target operating amount of the variable valve operating device is set according to the acquired temperature of the burned gas, so that the temperature of the burned gas that changes for each combustion cycle is precisely reflected. Thus, the internal EGR amount can be appropriately controlled, whereby the compression end temperature can be accurately controlled to the target compression end temperature, and more stable combustion by compression ignition can be ensured.

  According to a third aspect of the present invention, in the control device 1 for the internal combustion engine according to the second aspect, load detection means (crank angle sensor 21, accelerator opening sensor 25) for detecting a load (required torque BMEP) of the internal combustion engine 3 is provided. The burned gas temperature acquisition means calculates the burned gas temperature TEX according to the detected load of the internal combustion engine 3 (step 4 in FIG. 4, FIG. 5).

  The load on the internal combustion engine well reflects the temperature of the burnt gas. According to this configuration, the temperature of the burned gas is calculated according to the detected actual load of the internal combustion engine, so that a more accurate burned gas temperature can be acquired. Therefore, by setting the target operation amount so as to obtain the accurate temperature of the burned gas thus obtained, it is possible to ensure more stable combustion by compression ignition.

  According to a fourth aspect of the invention, in the control apparatus 1 for an internal combustion engine according to the second aspect, the fuel injection timing calculating means (ECU2) for calculating the injection timing TINJ of the fuel to be supplied from the fuel injection valve 4 to the cylinder 3a. Further, the burnt gas temperature acquisition means is characterized in that the burnt gas temperature TEX is calculated according to at least one of the calculated fuel injection timing TINJ and the fuel injection amount QINJ.

  The temperature of the burned gas changes according to the fuel injection timing. For example, when fuel is supplied into the cylinder from the fuel injection valve in the expansion stroke of the internal combustion engine, or in the compression stroke in addition to the intake stroke, the period from ignition to the start of the next combustion cycle By shortening, the temperature of burned gas becomes high. In addition, the temperature of burned gas becomes higher because the amount of fuel used for combustion increases as the fuel injection amount increases. According to this configuration, the temperature of the burned gas is calculated according to at least one of the calculated fuel injection timing and the fuel injection amount, so that a more accurate burned gas temperature can be acquired. Therefore, more stable combustion by compression ignition can be ensured.

  According to a fifth aspect of the invention, in the control device 1 for an internal combustion engine according to the first aspect, the next operation amount estimating means estimates the next operation amount of the variable valve device according to the response characteristic of the variable valve device. (Steps 13 and 14 in FIG. 6, FIG. 7).

  According to this configuration, since the next operation amount of the variable valve apparatus is estimated in accordance with the response characteristic of the variable valve apparatus, a more accurate next operation amount that reflects the response characteristic can be estimated. In addition, by correcting the required torque used for calculating the fuel injection amount so that the compression end temperature becomes the target compression end temperature in accordance with the next operation amount estimated as described above, the compression end of each combustion cycle is corrected. The temperature can be appropriately controlled to the target compression end temperature.

  According to a sixth aspect of the present invention, in the internal combustion engine control apparatus 1 according to any one of the first to fifth aspects, the internal combustion engine 3 is mounted as a power source in the vehicle V together with the motor 31, and the required torque correction is performed. Motor output setting means (ECU2, power drive unit 32, steps 21 to 23 in FIG. 10) for setting the output of the motor 31 so as to compensate the corrected required torque BMEP when the required torque BMEP is corrected by the means. ) Is further provided.

  According to this configuration, when the required torque is corrected, the corrected required torque is compensated by the output of the motor, so that the output requested by the driver can be ensured and drivability is maintained well. be able to.

1 is a diagram schematically showing a control device for an internal combustion engine according to an embodiment of the present invention together with the internal combustion engine. It is a schematic diagram which shows schematic structure of a cam phase variable mechanism. It is a figure which shows the valve lift curve of an exhaust valve when a cam phase is set to the most retarded angle value (solid line) and the most advanced angle value (two-dot chain line) by the cam phase variable mechanism. It is a flowchart which shows the calculation process of a target cam phase. It is a map for calculating burnt gas temperature. It is a flowchart which shows the calculation process of fuel injection amount. It is a map for calculating the next phase. It is a map for calculating a correction request torque. 3 is a map for calculating a fuel injection amount. It is a flowchart which shows the setting process of a motor torque. It is a figure which shows the operation example obtained by the control processing of the internal combustion engine by embodiment with a comparative example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a control device 1 to which the present invention is applied includes an ECU 2, which performs various control processes of an internal combustion engine (hereinafter referred to as “engine”) 3 as will be described later.

  The engine 3 is mounted on a vehicle V, and the vehicle V includes a motor 31 (electric motor) in addition to the engine 3 as a drive source. In addition, the vehicle V stops the motor 31 and drives the vehicle V with only the engine 3, the combined mode of driving the vehicle V with both the engine 3 and the motor 31, or stops the engine 3 and stops the motor The vehicle is driven by the motor drive mode in which the vehicle V is driven only by 31.

  The engine 3 is a 4-cylinder (only one shown) type gasoline engine, and a combustion chamber 3d is formed between the piston 3b and the cylinder head 3c of each cylinder. The cylinder head 3c is provided with an intake port 3e and an exhaust port 3f for each cylinder 3a. The intake port 3e has an intake manifold 12a of an intake pipe 12, and the exhaust port 3f has an exhaust pipe 14 exhaust. A manifold 14a is connected. A pair of intake valves 8, 8 are provided at the opening of the intake port 3e, and a pair of exhaust valves 9, 9 are provided at the opening of the exhaust port 3f so as to face the combustion chamber 1d.

  The intake manifold 12a is provided with a fuel injection valve (hereinafter referred to as “injector”) 4 so as to face the intake port 3e for each cylinder 3a. The injector 4 injects fuel boosted by a fuel pump (not shown) toward the intake port 3e. The fuel injection amount QINJ and the fuel injection timing TINJ of the injector 4 are calculated by the ECU 2 and controlled by outputting a control signal based on them.

  Further, the engine 3 includes an intake camshaft 6 and an exhaust camshaft 7. These intake and exhaust camshafts 6 and 7 have an intake cam 6a and an exhaust cam 7a for opening and closing the intake valve 8 and the exhaust valve 9, respectively. The intake and exhaust camshafts 6 and 7 are connected to the crankshaft 3g via a timing belt (not shown), and rotate once for every two rotations of the crankshaft 3g. A cam phase varying mechanism 10 is provided at one end of the exhaust camshaft 7.

  The cam phase variable mechanism 10 is operated by hydraulic pressure, and advances or retards the phase of the exhaust cam 7a with respect to the crankshaft 3g (hereinafter referred to as "cam phase CAEX") steplessly, thereby controlling the opening / closing timing of the exhaust valve 9. change. Thus, by changing the valve overlap between the intake valve 8 and the exhaust valve 9, the internal EGR amount is increased or decreased, and the charging efficiency is changed. The valve overlap in this case is a so-called negative overlap in which the intake valve 8 is opened after the exhaust valve 9 is closed.

  As shown in FIG. 2, the cam phase variable mechanism 10 has an electromagnetic valve 10a. This electromagnetic valve 10a is a combination of a spool valve mechanism 10b and a solenoid 10c, and is connected to the advance chamber 15 and the retard chamber 16 via an advance oil passage 17a and a retard oil passage 17b, respectively. . The electromagnetic valve 10a controls the operating oil pressure POIL supplied from the hydraulic pump 11, and supplies the operating oil pressure POIL to the advance chamber 15 and the retard chamber 16 as the advance oil pressure Pad and the retard oil pressure Prt, respectively. The solenoid 10c changes the advance hydraulic pressure Pad and the retard hydraulic pressure Prt by moving the spool valve body of the spool valve mechanism 10b within a predetermined range by the phase control input U_CAEX from the ECU 2.

  The hydraulic pump 11 is of a mechanical type connected to the crankshaft 3g. As the crankshaft 3g rotates, the hydraulic oil stored in the oil pan 3h of the engine 3 is sucked through the oil passage 11a and boosted. After that, the oil is supplied to the electromagnetic valve 10a through the oil passage 11a.

  In the cam phase variable mechanism 10 having the above-described configuration, while the hydraulic pump 11 is in operation, the solenoid valve 10a operates in accordance with the phase control input U_CAEX, so that the advance hydraulic pressure Pad is transferred to the advance chamber 15 and the retard hydraulic pressure Prt is changed. As a result, the aforementioned cam phase CAEX continuously changes between a predetermined most retarded value and the most advanced angle value, whereby the valve timing of the exhaust valve 9 is The step is changed in a stepless manner between the most retarded timing shown by the solid line in FIG. 3 and the most advanced timing shown by the two-dot chain line.

  A cam angle sensor 24 is provided at the end of the exhaust camshaft 7 opposite to the cam phase variable mechanism 10. The cam angle sensor 24 outputs a CAM signal, which is a pulse signal, to the ECU 2 every predetermined cam angle (for example, 1 °) as the exhaust camshaft 7 rotates. The ECU 2 calculates the actual cam phase CAEX from this CAM signal and the CRK signal and TDC signal described later.

  On the other hand, a crank angle sensor 21 is provided on the crankshaft 3g. The crank angle sensor 21 outputs a CRK signal and a TDC signal, which are pulse signals, with the rotation of the crankshaft 3g.

  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. The TDC signal is a signal indicating that the piston 3b is in a predetermined crank angle position near the top dead center at the start of the intake stroke in any cylinder 3a. In this example in which the engine 3 is a four-cylinder type, the crank angle 180 Output every degree.

  A water temperature sensor 22 is attached to the main body of the engine 3. The water temperature sensor 22 detects the engine water temperature TW, which is the temperature of the cooling water circulating in the main body of the engine 3, and outputs a detection signal to the ECU 2.

  On the other hand, a throttle valve 13 is provided in the intake pipe 12 of the engine 3. An actuator 13 a is connected to the throttle valve 13. The opening degree of the throttle valve 13 is controlled by the ECU 2 by controlling the actuator 13 a according to the operating state of the engine 3, thereby controlling the amount of intake air to the engine 3.

  An intake air temperature sensor 23 is provided on the downstream side of the throttle valve 13 in the intake pipe 12. The intake air temperature sensor 23 detects the intake air temperature (hereinafter referred to as “intake air temperature”) TA and outputs a detection signal to the ECU 2.

  Further, the ECU 2 outputs a detection signal representing an operation amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle from the accelerator opening sensor 25.

  The motor 31 is directly connected to the crankshaft 3g of the engine 3 and is connected to driving wheels (not shown) of the vehicle V via an automatic transmission (not shown) having a torque converter. ing. Further, the motor 31 is connected to a battery 33 which is a drive source thereof via a power drive unit 32. The power drive unit 32 is composed of an electric circuit including an inverter. Further, the motor 31 has a function as a generator that generates electric power using rotational energy of drive wheels (not shown), and the generated electric energy is charged to the battery 33 via the power drive unit 32 ( Regenerated).

  The ECU 2 includes a microcomputer (not shown) including a CPU, a RAM, a ROM, an input / output interface (all not shown), and the like. The detection signals of the above-described sensors 21 to 25 are respectively input to the ECU 2, A / D converted and shaped by the input interface, and then input to the CPU. In accordance with these input signals, the CPU executes various arithmetic processes based on a control program stored in the ROM. For example, the ECU 2 calculates the phase control input U_CAEX by feedback control so that the detected cam phase CAEX converges to the target cam phase CAEXCMD.

  In the present embodiment, the ECU 2 includes the required torque calculation means, the fuel injection amount calculation means, the target compression end temperature setting means, the target operation amount setting means, the next operation amount estimation means, the required torque correction means, and the fuel injection amount calculation means. These correspond to burned gas temperature acquisition means, motor output setting means, and fuel injection timing calculation means.

  Next, the control process of the engine 3 executed by the ECU 2 will be described with reference to FIGS. This control process is executed in synchronization with the generation of the TDC signal.

  FIG. 4 shows a setting process of a target cam phase CAEXCMD that is a target of the cam phase CAEX. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), a target compression end temperature T_TDCCMD that is a target of the compression end temperature T_TDC is set to a predetermined compression ignition temperature THCCI (for example, 730 ° C.). The compression end temperature T_TDC is the temperature in the cylinder 3a when the piston 3b is located at the top dead center of the compression stroke. The compression ignition temperature THCCI corresponds to the temperature at which the mixture of gasoline and air burns by compression ignition at the top dead center of the compression stroke, and is obtained in advance by experiments or the like.

  Next, in step 2, a pre-compression ignition temperature TPREHCCI is calculated by searching a predetermined map (not shown) according to the target compression end temperature T_TDCCMD, the predetermined compression ratio CR of the engine 3 and the engine water temperature TW. . This pre-compression ignition temperature TPREHCCI corresponds to the temperature (hereinafter referred to as “pre-compression temperature”) T_IVC immediately before the start of the compression stroke such that the target compression end temperature T_TDCCMD (= compression ignition temperature THCCI) is obtained, In this map, the pre-compression ignition temperature TPREHCCI is set to a larger value as the target compression end temperature T_TDCCMD is higher, the compression ratio CR is lower, and the engine coolant temperature TW is lower.

  Next, in step 3, the required torque BMEP required for the engine 3 is calculated by searching a predetermined map (not shown) according to the engine speed NE and the accelerator pedal opening AP. In this map, the required torque BMEP is set to a larger value as the engine speed NE is higher and as the accelerator pedal opening AP is higher.

  Next, in step 4, by searching the map shown in FIG. 5 according to the calculated required torque BMEP and the engine speed NE, the temperature of the burned gas generated by the combustion of the air-fuel mixture (hereinafter referred to as “burned fuel”). TEX) (referred to as “gas temperature”). In this map, the burnt gas temperature TEX is set to a larger value as the required torque BMEP is higher and the engine speed NE is higher than the three engine speeds NE1 to NE3 (NE1 <NE2 <NE3). Has been. When the engine speed NE is other than the above three values, the burnt gas temperature TEX is calculated by interpolation calculation.

  Next, in step 5, the compression ignition EGR rate RHCCI is calculated by searching a predetermined map (not shown) according to the calculated burned gas temperature TEX, pre-compression ignition temperature TPREHCCI and intake air temperature TA. . This compression ignition EGR rate RHCCI corresponds to an internal EGR rate REGR at which the pre-compression ignition temperature TPREHCCI is obtained. The internal EGR rate REGR represents the ratio of the burnt gas amount to the total gas amount (fresh air amount + burnt gas amount) existing in the combustion chamber 3d after the intake valve 8 is closed. In the above map, the compression ignition EGR rate RHCCI is set to a larger value as the pre-compression ignition temperature TPREHCCI is higher, the intake air temperature TA is lower, and the burned gas temperature TEX is lower.

  Next, in step 6, the target cam phase CAEXCMD is calculated by searching a predetermined map (not shown) according to the calculated compression ignition EGR rate RHCCI, and this process is terminated. In this map, the target cam phase CAEXCMD is set to have a more advanced value as the internal EGR rate REGR is larger.

  As a result of setting the target cam phase CAEXCMD as described above, by controlling the cam phase CAEX to the target cam phase CAEXCMD, the internal EGR rate REGR becomes the compression ignition EGR rate RHCCI, and the pre-compression temperature I_IVC is before the compression ignition. The temperature TPREHCCI is controlled so that the compression end temperature T_TDC becomes the compression ignition temperature THCCI, and the air-fuel mixture is combusted by compression ignition.

  FIG. 6 shows a process for calculating the fuel injection amount QINJ of the injector 4. In this process, first, in step 11, the phase difference DCAEX between the target cam phase CAEXCMD and the cam phase (hereinafter referred to as “current phase”) CAEX (k) in the current combustion cycle is calculated.

  Next, in step 12, it is determined whether or not the phase difference DCAEX is smaller than zero. When this answer is YES, that is, when the cam phase CAEX is changing to the advance side toward the target cam phase CAEXCMD, the next combustion is performed in step 13 by using the retard angle map shown in FIG. The phase (hereinafter referred to as “next phase”) CAEX (k + 1) in the cycle is calculated.

  In this map, the response characteristic of the cam phase CAEX with respect to the target cam phase CAEXCMD is obtained in advance by experiment, and the result is expressed. Using this map, the next phase CAEX (k + 1) is calculated as follows. Done. First, the map is searched, and the timing t1 corresponding to the current phase CAEX (k) is calculated. Next, based on the engine speed NE, a time difference Δtc from the current combustion cycle to the next combustion cycle is calculated. Next, the next combustion timing t2 is calculated by adding the calculated time difference Δtc to the timing t1. Then, the map is searched, and the cam phase CAEX corresponding to the timing t2 is calculated as the next phase CAEX (k + 1).

  On the other hand, if the answer to step 12 is NO and the cam phase CAEX is changing toward the retard angle toward the target cam phase CAEXCMD, in step 14, the next phase CAEX is used using a predetermined advance map. (K + 1) is calculated. Although not shown in the figure, this advance map is obtained by experimentally obtaining the response characteristic of the cam phase CAEX with respect to the target cam phase CAEXCMD in the same manner as the map of FIG. The calculation of the phase CAEX (k + 1) is performed in the same manner as in the case of using the retardation map described above.

  Next, in step 15, the correction required torque BMEPCOR is calculated by searching the map shown in FIG. 8 according to the calculated next phase CAEX (k + 1). This correction request torque BMEPCOR corresponds to a request torque BMEP that causes the compression end temperature T_TDC at the next phase CAEX (k + 1) to become the compression ignition temperature THCCI. In this map, the correction request torque BMEPCOR is the next phase CAEX (k + 1). The larger the value is, the larger the value is set.

  Next, in step 16, the map shown in FIG. 9 is searched according to the correction required torque BMEPCOR, thereby calculating the fuel injection amount QINJ and the present process is terminated. In this map, the fuel injection amount QINJ is set to a larger value as the correction request torque BMEPCOR is larger.

  FIG. 10 shows a process for setting the motor torque TQMCMD to be output from the motor 31. In this process, first, in step 21, it is determined whether or not the required torque BMEP of the engine 3 is larger than the corrected required torque BMEPCOR. When the answer is YES and the required torque BMEPCOR is limited by the corrected required torque BMEPCOR calculated in step 15, in step 22, the difference between the required torque BMEP and the corrected required torque BMEPCOR is expressed as a torque deviation DBMEP (= BMEP-BMEPCOR).

  Next, in step 23, the motor torque TQMCMD is set to the torque deviation DBMEP, and this process ends. When the motor torque TQMCMD is set in this way, the electric power corresponding to the motor torque TQMCMD is supplied from the power drive unit 32 to the motor 31, whereby torque corresponding to the motor torque TQMCMD is output from the motor 31.

  On the other hand, if the answer to step 21 is NO and BMEP ≦ BMEPCOR, that is, if the required torque BMEP is not limited by the correction required torque BMEPCOR, the motor torque TQMCMD is set to a value 0, and this process ends.

  FIG. 11 shows an operation example (the same figure (a)) obtained by the control of the present embodiment together with a comparative example (the same figure (b)). It is assumed that the intake air temperature TA is constant and the required torque BMEP is greatly increased from the previous combustion cycle (hereinafter referred to as “previous cycle”).

  When the compression end temperature T_TDC is the compression ignition temperature THCCI, the engine 3 can combust the air-fuel mixture stably by compression ignition. However, when the compression end temperature T_TDC is higher than the compression ignition temperature THCCI, that is, when the cam phase CAEX is in the advance side region (upper side in the figure) from the boundary line indicated by T_TDC = THCCI in the figure. Since the compression end temperature T_TDC is high, the temperature in the cylinder 3a reaches the compression ignition temperature THCCI before the piston 3b reaches the top dead center, and knocking is likely to occur. In this region, the farther from the boundary line, the higher the compression end temperature T_TDC, and the more likely knocking occurs.

  On the other hand, when the compression end temperature T_TDC is lower than the compression ignition temperature THCCI, that is, when the cam phase CAEX is in the retarded side region (lower side of the figure) with respect to the boundary line indicated by T_TDC = THCCI in the figure. Since the compression end temperature T_TDC is low, even if the piston 3b reaches the top dead center, the compression end temperature T_TDC does not rise to the compression ignition temperature THCCI, and misfire is likely to occur. In this region, the farther from the boundary line, the lower the compression end temperature T_TDC, and the easier it is to misfire.

  Unlike the embodiment, the comparative example shown in FIG. 6A is an example in which the fuel injection amount QINJ is set according to the required torque BMEP without correcting the required torque BMEP with the corrected required torque BMEPCOR. In this case, it is calculated according to the burned gas at the burned gas temperature TEX (k−1) generated in the previous cycle and the required torque BMEP (k) of the current combustion cycle (hereinafter referred to as “current cycle”). The fuel with the fuel injection amount QINJ and the intake air at a predetermined temperature are mixed in the combustion chamber 3d, whereby an air-fuel mixture is generated. The cam phase at this time is CAEX (k), whereby the internal EGR rate is controlled to REGR (k), and the air-fuel mixture burns in a state where the compression end temperature T_TDC is controlled to the compression ignition temperature THCCI.

  After that, in the next combustion cycle (hereinafter referred to as “next cycle”), it was calculated according to the burnt gas at the burnt gas temperature TEXA (k) generated in the current cycle and the required torque BMEP (k + 1) of the next cycle. An air-fuel mixture of fuel and intake air by the fuel injection amount QINJ is generated in the combustion chamber 3d. In this case, since the cam phase CAEX is delayed with respect to a large increase in the required torque BMEP, the next phase CAEX (k + 1) still reaches the target cam phase CAEXCMD corresponding to the required torque BMEP (k) of the current cycle. However, it is on the retard side, and is located in the region above the boundary line in FIG. Therefore, the internal EGR rate REGR (k + 1) of the next cycle becomes a value higher than the value RHCCI corresponding to the target cam phase CAEXCMD, and as a result, the compression end temperature T_TDC becomes higher than the compression ignition temperature THCCI, so that knocking occurs. Is likely to occur.

  On the other hand, as shown in FIG. 6B, according to the embodiment, a correction required torque BMEPCOR (k) smaller than the required torque BMEP (k) is set in the current cycle (step 15 in FIG. 6). A smaller amount of fuel injection amount QINJ is set in accordance with the correction required torque BMEPCOR (k) (step 16 in FIG. 6). Since the correction required torque BMEPCOR (k) is set as described above, the compression end temperature T_TDC of the next cycle is controlled to substantially coincide with the compression ignition temperature THCCI, and as a result, knocking and misfire can be suppressed and stable. Combustion is ensured.

  As described above, according to the present embodiment, the next phase CAEX (k + 1) of the cam phase variable mechanism 10 is estimated, and the compression end temperature T_TDC in the next combustion cycle is estimated according to the estimated next phase CAEX (k + 1). Is calculated as a correction required torque BMEPCOR used for setting the fuel injection amount QINJ so that the compression ignition temperature THCCI becomes. As a result, even when the required torque BMEP changes significantly, the compression end temperature T_TDC can be accurately controlled to the compression ignition temperature THCCI in each combustion cycle, whereby the air-fuel mixture supplied into the cylinder 3a is stabilized by compression ignition. And can be burned.

  In each combustion cycle, the target cam phase CAEXCMD is set in accordance with the burnt gas temperature TEX, so that the internal EGR rate REGR is appropriately controlled while finely reflecting the burnt gas temperature TEX that changes with each burn cycle. can do. Thereby, the compression end temperature T_TDC can be accurately controlled to the compression ignition temperature THCCI, and more stable combustion by compression ignition can be ensured.

  Moreover, since the burnt gas temperature TEX is calculated according to the required torque BMEP, a more accurate burned gas temperature TEX can be acquired. Therefore, by setting the target cam phase CAEXCMD so that the accurate burned gas temperature TEX acquired in this way can be obtained, more stable combustion by compression ignition can be ensured.

  Further, since the next phase CAEX (k + 1) is estimated according to the response characteristic of the cam phase variable mechanism 10 using the map of FIG. 7, a more accurate next phase CAEX (k + 1) reflecting the response characteristic is estimated. be able to. In addition, by calculating the correction required torque BMEPCOR so that the compression end temperature T_TDC becomes the compression ignition temperature THCCI according to the next phase CAEX (k + 1) estimated in this way, the compression end temperature of each combustion cycle is calculated. T_TDC can be appropriately controlled to the compression ignition temperature THCCI.

  Furthermore, when the required torque BMEPOR is limited by the correction required torque BMEPCOR, the torque deviation DBMEP is set as the motor torque TQMCMD and output from the motor 31, so that the output requested by the driver can be ensured. Can be maintained well.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the burnt gas temperature TEX is calculated according to the required torque BMEP, but in addition to or instead of this, another parameter indicating the load of the engine 3, for example, the detected intake air amount Or depending on the intake pressure.

  In addition to or instead of these parameters representing the load of the engine 3, the burned gas temperature TEX may be calculated according to the fuel injection amount QINJ. Further, when the direct injection type engine 3 that directly injects fuel into the combustion chamber 1d is used, the burned gas temperature TEX is calculated according to the fuel injection timing TINJ and / or the fuel injection amount QINJ. May be.

  Further, in the embodiment, as the variable valve operating apparatus for controlling the internal EGR, the cam phase variable mechanism 10 that advances or delays the opening / closing timing of the exhaust valve 9 is used, but instead, for example, the exhaust valve 9 An exhaust lift variable mechanism that changes the lift of the engine may be used. In that case, the lift of the exhaust valve 9 is used as the operation amount of the variable valve operating apparatus.

  Further, in the embodiment, in order to control the internal EGR, the exhaust valve 9 is used as the engine valve, and the opening / closing timing of the exhaust valve 9 is changed, but instead, the intake valve 8 or the intake valve 8 and The exhaust valve 9 may be used to change its opening / closing timing and lift.

  In the embodiment, the compression ignition temperature THCCI is a fixed value. However, for example, the atmospheric pressure PA may be detected and corrected accordingly. In the embodiment, the target compression end temperature T_TDCCMD is set to a predetermined value, but may be set to a predetermined temperature range (for example, 720 to 740 ° C.). In that case, for example, the correction request torques such that the compression end temperature T_TDC becomes the upper limit value and the lower limit value of the temperature range are calculated, and the fuel injection amount QINJ is calculated according to the average value thereof. .

  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 (Request torque calculation means, Fuel injection amount calculation means, Target compression end temperature setting means, Target operation amount setting means, Next operation amount estimation means, Request torque correction means,
Fuel injection amount calculation means, burnt gas temperature acquisition means, motor output setting means,
Fuel injection timing calculation means)
3 Engine (Internal combustion engine)
3a cylinder 4 injector (fuel injection valve)
9 Exhaust valve (engine valve)
10 Cam phase variable mechanism (Variable valve operating device)
21 Crank angle sensor (load detection means)
24 Accelerator opening sensor (load detection means)
31 Motor 32 Power drive unit (Motor output setting means)
V vehicle
CAEX cam phase (operation amount of variable valve operating device)
BMEP required torque (load of internal combustion engine)
QINJ Fuel injection amount
TINJ Fuel injection timing T_TDC Compression end temperature T_TDCCMD Target compression end temperature CAEXCMD Target cam phase (target operation amount of variable valve gear)
CAEX (k + 1) Next phase (Next operation amount of variable valve gear)
TEX Burnt gas temperature (burnt gas temperature)

Claims (6)

By changing the operating characteristic of the engine valve that is at least one of the intake valve and the exhaust valve in accordance with the operation amount of the variable valve operating device, the internal EGR that causes the burned gas to remain in the cylinder is controlled, and the inside of the cylinder A control device for an internal combustion engine that combusts the air-fuel mixture supplied to the engine by compression ignition,
Required torque calculating means for calculating required torque required for the internal combustion engine;
Fuel injection amount calculating means for calculating a fuel injection amount to be supplied from the fuel injection valve to the cylinder according to the calculated required torque;
Target compression end temperature setting means for setting a target compression end temperature, which is a target compression end temperature when performing combustion by compression ignition,
A target operating amount setting means for setting a target operating amount that is a target of the operating amount of the variable valve operating device corresponding to the internal EGR amount so as to obtain the target compression end temperature according to the calculated required torque; ,
A next operation amount estimating means for estimating a next operation amount of the variable valve operating device in a next combustion cycle according to the set target operation amount;
Requested torque correction means for correcting the required torque used for calculation of the fuel injection amount so that the compression end temperature in the next combustion cycle becomes the target compression end temperature according to the estimated next operation amount;
A control device for an internal combustion engine, comprising: It further comprises a burnt gas temperature acquisition means for acquiring the burnt gas temperature in the current combustion cycle,
2. The control device for an internal combustion engine according to claim 1, wherein the target operation amount setting means sets a target operation amount of the variable valve operating device in accordance with the acquired temperature of burned gas. . A load detecting means for detecting a load of the internal combustion engine;
3. The control apparatus for an internal combustion engine according to claim 2, wherein the burned gas temperature acquisition means calculates the temperature of the burned gas according to the detected load of the internal combustion engine. A fuel injection timing calculating means for calculating an injection timing of fuel to be supplied from the fuel injection valve to the cylinder;
The internal combustion engine according to claim 2, wherein the burnt gas temperature acquisition means calculates the burnt gas temperature according to at least one of the calculated fuel injection timing and fuel injection amount. Control device.   2. The control device for an internal combustion engine according to claim 1, wherein the next operation amount estimation means estimates the next operation amount of the variable valve device according to a response characteristic of the variable valve device. . The internal combustion engine is mounted on a vehicle as a power source together with a motor,
The motor output setting means for setting the output of the motor so as to compensate the corrected required torque when the required torque is corrected by the required torque correction means. Item 6. The control device for an internal combustion engine according to any one of Items 1 to 5.

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