JP4660462B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to calculation of an average effective pressure or the like in a spark ignition engine using gasoline fuel and control using the same.

  In an internal combustion engine, it is desirable to accurately obtain an output torque, more precisely, a net average effective pressure, and calculate an engine control parameter based on that. The technique of the following patent document 1 is proposed from the intention. In this technique, the target torque Tind is set according to the load, and the estimated value (estimated torque) Tbase of the current engine torque is calculated based on the engine speed, the air charge amount, etc. The corrected estimated torque Tcal is calculated by adding the integrated value obtained by integrating the deviation dT of the estimated torque Tbase to the estimated torque Tbase, and the ignition timing and the like are corrected according to the deviation DT between the target torque Tind and the corrected estimated torque Tcal. Therefore, the engine torque is corrected.

The technology described in Patent Document 1 is configured to accurately correct the excess or deficiency of the actual torque with respect to the target torque Tind while eliminating the influence of system variation in almost real time.
JP 2002-221068 A

  In the prior art described above, the engine torque can be estimated to some extent as long as the combustion state does not change at the same air charge amount. However, if EGR is introduced even when the air charge is the same, or if the combustion efficiency due to dilution changes, the combustion state changes, and it is not possible to cope with torque fluctuations at the time of combustion switching.

  Accordingly, an object of the present invention is to solve the above-described problems and to calculate the engine torque, more specifically, the net average effective pressure with high accuracy even when the combustion state changes, and to control the operation based on the calculation. It is to provide an engine control device.

In order to solve the above-described object, an internal combustion engine control apparatus according to claim 1 includes an air mass flow rate calculating means for calculating an air mass flow rate per cycle supplied to the internal combustion engine, the air mass flow rate and the fuel mass flow rate. A target equivalent ratio calculating means for calculating a target value of the equivalent ratio indicating the ratio of the fuel, the fuel mass flow obtained by calculating from the calculated air mass flow and the target value of the equivalent ratio to be supplied to the internal combustion engine Fuel mass flow rate calculation means for making a fuel mass flow rate per cycle, the combustion mode of the internal combustion engine is composed of a combustion mode by homogeneous mixture flame propagation, a combustion mode by stratified mixture flame propagation, and a combustion mode by self-ignition determines which of the combustion mode is selected, to obtain a job that can be taken out after searching the cycle by dividing the amount of heat supplied for the cycle Net thermal efficiency calculating means for calculating on the basis of the net thermal efficiency in at least the rotational speed and the determined combustion mode of the internal combustion engine to be, calorific value and the calculated fuel obtained from the property of the fuel to be supplied to the internal combustion engine based on the mass flow rate and the net thermal efficiency, the ratio between the target value with, the calculated brake mean effective pressure of the work to calculate the net mean effective pressure corresponding to a value obtained by dividing the volume of the internal combustion engine A net average effective pressure calculating means for calculating the instantaneous net average effective pressure by learning, and a control parameter calculating means for calculating the control parameter of the internal combustion engine based on the calculated instantaneous net average effective pressure. .

  In the control apparatus for an internal combustion engine according to claim 2, the net average effective pressure calculating means learns the calculated net average effective pressure in a ratio with a target value to calculate an average effective pressure correction coefficient. Then, the instantaneous net average effective pressure is calculated based on the calculated average effective pressure correction coefficient and the target value of the net average effective pressure.

  In the control apparatus for an internal combustion engine according to claim 3, the net average effective pressure calculating means is configured to stop the learning when the internal combustion engine is in an operation state that is not stable in combustion.

The control device for an internal combustion engine according to claim 1 calculates an air mass flow rate per cycle supplied to the internal combustion engine, and calculates a fuel mass flow rate obtained by calculating from a target value of the calculated air mass flow rate and an equivalence ratio. The fuel mass flow rate per cycle to be supplied to the internal combustion engine is calculated, the net thermal efficiency is calculated based on at least the rotational speed and combustion mode of the internal combustion engine, and the net average effective pressure is calculated based on the calorific value, fuel mass flow rate and net thermal efficiency. The calculated net average effective pressure is learned by a ratio with the target value to calculate the instantaneous net average effective pressure, and the control parameter of the internal combustion engine is calculated based on the calculated instantaneous net average effective pressure. Since it comprised as mentioned above, the net average effective pressure in the cycle can be calculated accurately. That is, since it is obtained before combustion, the net average effective pressure can be calculated with high accuracy without being affected by changes in the combustion state with the same air filling amount.

  In addition, since the actual torque generated by calculating the control parameter based on the instantaneous net average effective pressure can be matched, it is possible to absorb the torque variation due to the manufacturing variation of the internal combustion engine. Thereby, it is possible to reduce the torque fluctuation at the time of combustion switching, and it is possible to improve drivability. Further, optimum combustion can be performed in the set torque region, unnecessary emission and fuel consumption can be suppressed, and emission performance and fuel consumption performance can be improved.

  Furthermore, since the error between the net average effective pressure required in the internal combustion engine and the actually generated value can be reduced, the control margin associated with the error can be reduced. As a result, the work amount or capacity of an auxiliary machine such as an oil pump can be reduced, and fuel consumption performance can be improved. In addition, since the net average effective pressure can be calculated with high accuracy without using an expensive in-cylinder pressure sensor, the cost can be reduced.

  In the control apparatus for an internal combustion engine according to claim 2, the net average effective pressure calculating means learns the calculated net average effective pressure in a ratio with the target value to calculate an average effective pressure correction coefficient, Since the instantaneous net average effective pressure is calculated based on the calculated average effective pressure correction coefficient and the target value of the net average effective pressure, the effect described in the first aspect can be further improved.

  In the control apparatus for an internal combustion engine according to claim 3, the net average effective pressure calculating means is configured to stop learning when the internal combustion engine is in an unstable operating state during combustion. , Learning accuracy can be increased.

  The best mode for carrying out the control apparatus for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention.

  In FIG. 1, reference numeral 10 denotes a four-cylinder four-cycle spark ignition type internal combustion engine (only one cylinder is shown; hereinafter referred to as “engine”) using gasoline as fuel. In the engine 10, air (intake) that is drawn from the air cleaner 12 and passes through an intake pipe (schematically indicated by a dotted line or a broken line) 14 flows through an intake manifold 20 with the flow rate adjusted by a throttle valve 16, and two intake valves (Only one is shown) When the valve 22 is opened, it flows into the combustion chamber 24.

A first injector 26 is disposed in the intake port before the intake valve 22, and gasoline fuel pumped from a fuel tank (not shown) through a fuel supply pipe (not shown) is injected into the intake port (port) Spray). The gasoline fuel injected from the first injector 26 is mixed with the inflowing air to form an air-fuel mixture (pre-air mixture), and flows into the combustion chamber 24 when the intake valve 22 is opened.

  In addition to the first injector 26, a second injector 30 is disposed along the cylinder axis at the center of the top of the combustion chamber 24. Similarly, the pumped gasoline fuel is directly injected into the combustion chamber 24 (in-cylinder injection). .

  The first and second injectors 26 and 30 are connected to an ECU (Electronic Control Unit) 32 through a drive circuit (not shown), and a drive signal indicating a valve opening time is supplied from the ECU 32 through the drive circuit. Then, the valve is opened, and gasoline fuel corresponding to the valve opening time is injected.

  A spark plug 34 is disposed in the combustion chamber 24. The spark plug 34 is connected to the ECU 32 via an ignition device (not shown) such as an igniter. When an ignition signal is supplied from the ECU 32, a spark discharge is generated between the electrodes facing the combustion chamber 24. The mixture is thereby ignited and burned, driving the piston 36 downward. Exhaust gas (exhaust gas) generated by combustion flows to the exhaust manifold 42 when two exhaust valves (only one is shown) 40 are opened. The spark plug 34 is disposed so that the electrode is positioned in the vicinity of the exhaust valve 40 in the combustion chamber 24.

  Exhaust gas flows from an exhaust manifold 42 through an exhaust pipe (shown in broken lines) 44. A catalyst device 46 made of a three-way catalyst is disposed in the exhaust pipe 44. When the catalyst device 46 is in an active state, the exhaust gas is discharged into the atmosphere outside the engine after removing harmful components such as HC, CO, and NOx.

  The exhaust valve 40 and the intake valve 22 are connected to a variable valve opening characteristic mechanism 50. The valve opening characteristic variable mechanism 50 is connected to the ECU 32 and variably controls the valve opening / closing timing (phase angle) and the valve lift amount regardless of the rotation angle of the crankshaft (not shown) in accordance with an instruction from the ECU 32.

  For example, an internal EGR (Exhaust Gas Recirculation) is performed in which the exhaust valve 40 is advanced to close the valve timing, and the open timing of the intake valve 22 is retarded to cause the exhaust gas to remain in the cylinder. It is controlled to raise the temperature. The operation of the variable valve opening characteristic mechanism 50 is described in detail in Japanese Patent Application Laid-Open No. 2006-29159 previously proposed by the present applicant, and the description thereof is omitted here.

  The exhaust pipe 44 is connected to the intake pipe 14 via an EGR pipe (shown by a broken line) 52 in the vicinity of the downstream of the position where the throttle valve 16 is disposed. An EGR valve 52 a is inserted in the EGR pipe 52. The EGR valve 52a is electrically connected to the ECU 32 and, when driven, opens the EGR pipe 52 to recirculate a part of the exhaust gas to the intake system (external EGR).

  A turbocharger 54 is provided upstream of the catalyst device 46 in the exhaust pipe 44. As schematically shown in FIG. 1, the turbocharger 54 is disposed in the exhaust pipe 44, and is disposed in the intake pipe 14 while being connected to the turbine 54a and rotated by the exhaust gas passing therethrough. The compressor 54b is driven by a rotational force and supercharged.

  A throttle actuator (such as a pulse motor) 56 is connected to the throttle valve 16 disposed in the intake pipe 14, and the throttle valve 16 is opened and closed by the throttle actuator 56. That is, the throttle valve 16 is mechanically disconnected from the accelerator pedal 60 disposed on the driver's seat floor of a vehicle (not shown) on which the engine 10 is mounted, and the throttle valve 16 is operated by the accelerator pedal 60. And a DBW (Drive By Wire) mechanism 62 that opens and closes independently.

  The engine 10 is connected to an automatic transmission, more specifically, a belt-type CVT (Continuously Variable Transmission) 64. Although not shown, the CVT 64 has a drive pulley including a fixed pulley half fixed to the input shaft and a movable pulley half movable in the axial direction, and a fixed pulley half fixed to the counter shaft and the axial direction. A driven pulley composed of a movable pulley half which is freely movable, and a metal V-belt wound around the pulleys.

  The hydraulic oil pumped up from the reservoir 70 by the oil pump 66 driven by the engine 10 is supplied to the CVT 64 via the hydraulic circuit, thereby adjusting the side pressure for pressing the movable pulley half toward the fixed pulley half. . The rotation of the engine 10 input through the rotation of the crankshaft is shifted by the CVT 64 and transmitted to drive wheels (not shown) to drive the vehicle.

  The details of the CVT 64 are described in the prior art previously proposed by the present applicant, for example, Japanese Patent Application Laid-Open No. 2004-360853, and thus detailed description thereof is omitted.

  A crank angle sensor 72 is disposed in the vicinity of the crankshaft of the engine 10 and is obtained by subdividing a cylinder discrimination signal, a TDC signal indicating a TDC (top dead center) of each cylinder or a crank angle in the vicinity thereof, and a TDC signal. A crank angle signal is output. Those outputs are input to the ECU 32.

  The ECU 32 includes a microcomputer, and includes a CPU, ROM, RAM, A / D conversion circuit, input / output circuit, and counter (all not shown). The ECU 32 counts the crank angle signal among the input signals and calculates (detects) the engine speed NE.

  A hot wire type air flow meter 74 having a temperature detection element is disposed in the vicinity of the air cleaner 12, and outputs a signal indicating the mass flow rate Gair of air (intake air) sucked from the air cleaner 12 and a signal indicating its temperature TA. To do.

  A MAP sensor 76 is disposed downstream of the throttle valve 16 in the intake pipe 14 to output a signal indicating the intake pipe pressure PBA in absolute pressure, and a throttle opening sensor 80 is disposed in the throttle valve 16. A signal corresponding to the position (throttle opening) TH is output.

  A water temperature sensor 82 is disposed in a cooling water passage (not shown) of the engine 10 and outputs a signal corresponding to the engine cooling water temperature TW. An accelerator opening sensor 84 is provided in the vicinity of the accelerator pedal 60 and outputs a signal corresponding to an accelerator opening (indicating engine load) AP indicating the amount of depression of the accelerator pedal of the driver. A wide area air-fuel ratio sensor 86 is disposed upstream of the catalyst device 46 in the exhaust system, and outputs a signal proportional to the oxygen concentration (ie, air-fuel ratio) of the exhaust gas flowing through that portion.

  The output of the sensor group described above is also input to the ECU 32. The ECU 32 controls the combustion mode (combustion mode) according to the command stored in the ROM based on the input value, and calculates the net average effective pressure.

  In addition to the ECU 32, a second ECU (electronic control unit) 90 is also provided. The second ECU 90 is also a microcomputer, and includes a CPU, ROM, RAM, A / D conversion circuit, input / output circuit, and counter (all not shown). The second ECU 90 is configured to be communicable with the ECU 32, determines a gear ratio based on data input from the ECU 32 and an output from a vehicle speed sensor (not shown), and presses the movable pulley half toward the fixed pulley half in the CVT 64. The side pressure is controlled, that is, the operation of the automatic transmission is controlled.

  Here, the combustion mode control executed by the ECU 32 will be described.

  The first injector 26 injects fuel when the engine 10 is in the high load region, and the second injector 30 is driven to inject fuel in all the load regions of the engine 10. The second injector 30 injects fuel conically around the cylinder axis, and the fuel injection density is uneven in the circumferential direction, and the fuel injection density in the direction toward the spark plug 34 is higher than that in the other direction. The height is also high.

As a result, the fuel a second injector 30 injects, the periphery of the spark plug 34 in the combustion chamber 24 while the rich mixture region R1 becomes a value of the rich side air-fuel ratio is formed, the combustion chamber 2 4 Other portions are configured such that a lean air-fuel mixture region R2 that is leaner than the stoichiometric air-fuel ratio is formed.

  The control of the combustion mode will be described with reference to FIG. 2. When the engine 10 is in the low and medium rotation range and the required torque (instantaneous net average effective pressure) Pmcmdf (described later) is in the low load region around 400 kPa. The fuel injected from the second injector 30 is controlled so that a partially rich stratified mixture is formed near the spark plug 34 at the air-fuel ratio. At this time, the internal EGR is introduced through the valve opening characteristic variable mechanism 50.

  When this stratified mixture is compressed in the compression stroke, the rich mixture region R1 in the vicinity of the ignition plug 34 is self-ignited, and the entire mixture in the combustion chamber 24 is combusted. In this low load region, the air-fuel mixture is leaner than the stoichiometric air-fuel ratio in most of the combustion chamber 24 at the air-fuel ratio, so the combustion temperature is low and the concentration of NOx in the exhaust gas can be suppressed to an extremely low value.

  In the region where the required torque is 300 kPa or less, a stratified (diffusion) mixture is formed and the air-fuel ratio is controlled to be leaner than the stoichiometric air-fuel ratio. In this region, the exhaust gas recirculation amount by the internal EGR is increased.

  On the other hand, when the required torque of the engine 10 is in a high load region from 300 kPa to WOT, the fuel mixture injected from the first injector 26 is largely homogeneous in the combustion chamber 24 and leaner than the stoichiometric air-fuel ratio. The air region R2 is formed, and control is performed so that the rich air-fuel mixture region R1 is formed in the vicinity of the spark plug 34 by the fuel injected from the second injector 30.

  By controlling the EGR amount in the relatively low load region of the high load region, the rich mixture region R1 in the vicinity of the spark plug 34 can be self-ignited, and in the relatively high load region, the spark plug can be ignited. Thus, it is possible to perform spark type self-ignition in which the rich mixture region R1 is ignited using the spark generated by the spark 34 as a spark, and the lean mixture region R2 is compressed and ignited by heat generated by flame propagation in the rich mixture region R1. Even in this high load region, since the air-fuel ratio of the air-fuel mixture is lean in most of the combustion chamber 24, the combustion temperature is low, and the concentration of NOx in the exhaust gas can be suppressed to a low value.

  Further, as shown in FIG. 2, when the engine 10 is in a high rotation range, flame propagation combustion is performed with a uniform mixture. In a region where the load is high, supercharging is performed via the turbocharger 54. Thus, in this embodiment, according to the load and the rotational speed, any one of the three combustion modes of the combustion mode by the homogeneous mixture flame propagation, the combustion mode by the stratified mixture flame propagation, and the combustion mode by self-ignition is selected. The

  The structure of the second injector 30 and the formation of the rich air-fuel mixture region R1 are described in detail in the application previously proposed by the present applicant in Japanese Patent Application No. 2006-286707. Is omitted.

  Next, operations of the control device for the internal combustion engine according to this embodiment, such as calculation of the net average effective pressure executed by the ECU 32, will be described.

  FIG. 3 is a flowchart showing the operation, specifically, the operation of the ECU 32. The illustrated program is executed at a predetermined crank angle near the TDC of each cylinder.

  Explaining below, the air mass flow rate Gair per cycle supplied to the engine 10 in S10 is calculated. That is, by dividing the mass flow rate of the intake air obtained from the output of the air flow meter 74 by the engine speed NE, the air mass flow rate per cycle (combustion cycle) consisting of four strokes of intake, compression, explosion, and exhaust. Gair is calculated.

  Next, in S12, a target equivalent ratio KCMD is calculated. That is, the target value of the equivalence ratio indicating the ratio of the air mass flow rate Gair supplied to the engine 10 and the fuel mass flow rate Gfuel (described later) is calculated or determined in accordance with the change in the combustion mode controlled based on the aforementioned load. Is done. The target equivalent ratio KCMD is a value indicating the air-fuel ratio as an equivalent ratio.

  Next, in S14, the fuel mass flow rate Gfuel is calculated from the calculated air mass flow rate Gair and the target equivalent ratio KCMD. Specifically, the fuel mass flow rate Gfuel is calculated as (1 / 14.7) × target equivalence ratio KCMD × air mass flow rate Gair as the fuel mass flow rate per cycle to be supplied to the engine 10.

  Next, in S16, the net thermal efficiency ηe is calculated based on the operating state of the engine 10. The net thermal efficiency ηe is obtained by dividing the net work We that can be taken out through the above cycle by the amount of heat Q supplied for the above cycle.

  The net work We is derived from the illustrated work Wi, which is less than the theoretical work Wth predicted based on the theoretical cycle, such as cooling loss, gas leakage, intake / exhaust loss, and so on. Since the value obtained by subtracting the work and converting the output that can be actually taken out from the crankshaft of the engine 10 into the work is meant, the net thermal efficiency ηe in this embodiment also means a corresponding value.

  Specifically, the net thermal efficiency ηe is calculated based at least on the engine speed NE, the target value Pmcmd of the net average effective pressure, and the combustion mode. FIG. 4 shows the target value Pmcmd of the net average effective pressure and the characteristics of the net thermal efficiency ηe set according to the combustion mode. As described above, the combustion mode is composed of the homogeneous mixture flame propagation combustion mode, the stratified mixture flame propagation mode, and the self-ignition combustion mode.

  Such characteristics are set for each engine speed NE. In S16, the illustrated thermal characteristics ηe are calculated by searching the illustrated characteristics from the detected engine speed NE, the target value Pmcmd of the net average effective pressure, and the selected combustion mode. The Since the characteristic is set for each engine speed NE500 rpm, the value between them is calculated by interpolation.

  Next, in S18, the net average effective pressure Pme is calculated according to the equation shown based on the constant C, the calorific value Cv, the calculated fuel mass flow rate Gfuel and the net thermal efficiency ηe. The net average effective pressure Pme is a value corresponding to a value obtained by dividing the net work We described above by the volume of the engine 10. The constant C is a constant value, and the calorific value Cv is also a constant value determined according to the properties of the fuel to be supplied to the engine 10. The “net” in the net average effective pressure means a value corresponding to the net compared with the theory and illustration, as with the net thermal efficiency.

  Next, in S20, it is determined whether or not the operating state of the engine 10 is in a stable operating state in combustion.

  For example, when the combustion mode is being switched, or when a predetermined time (for example, 500 msec) has not elapsed since the switching, or the fuel supply stop (fuel cut) is executed, or the fuel supply is resumed. However, if the same predetermined time has not elapsed, the torque fluctuation is large, so that it is determined that the operation state is not stable in combustion.

  In addition, even after the engine is started, the operation of the engine 10 is not stable until the warm-up is finished and the engine cooling water temperature TW rises to a predetermined temperature or higher, and the torque fluctuation is also large. Judge that it does not. Therefore, an operation state that is not stable in combustion means an operation state in which torque fluctuation is large.

  When the result in S20 is affirmative, the program proceeds to S22, in which the calculated net average effective pressure Pme is learned with the target value Pmcmd. More specifically, the calculated net average effective pressure Pme is calculated according to the equation shown in FIG. To calculate the average effective pressure correction coefficient Kpmref (n).

  In the equation, n represents a discrete system sample time, Kpmref (n) represents a value (current value) at the current time (current execution time in the flowchart of FIG. 3), and Kpmref (n−1) represents the previous time. The value (previous value) at (previous execution time in FIG. 3 flow chart) is shown.

  As described above, the average effective pressure correction coefficient Kpmref (n) is obtained by multiplying the value obtained by multiplying the ratio of the net average effective pressure Pme and the target value Pmcmd by the weighting coefficient x to the average effective pressure correction coefficient previous value Kpmref (n− It is calculated by obtaining a weighted average value obtained by adding a value obtained by multiplying 1) by 1.0 and the difference between the weighting factor x. The reason why the ratio between the net average effective pressure Pme and the target value Pmcmd is used is that it is more convenient for calculation to learn by the multiplication term, and a calculated value is obtained.

  Next, in S24, based on the calculated average effective pressure correction coefficient Kpmref and the target value Pmcmd of the net average effective pressure, more specifically, both are multiplied to calculate the instantaneous net average effective pressure Pmcmdb.

  If the result in S20 is NO, S22 is skipped. That is, since the calculation accuracy is lowered because the torque fluctuation is large and the control parameter is also greatly changed, the above learning is stopped. In that case, the previous value is used in the processing of S24.

  Next, as shown in S100 of the flowchart of FIG. 5, the second ECU 90 controls the lateral pressure of the CVT 64 based on the calculated net average effective pressure Pme. At that time, the instantaneous net average effective pressure Pmcmdfb may be used.

  Further, as shown in S200 of the flowchart of FIG. 6, the ECU 32 controls the control parameters of the engine 10, for example, the target throttle opening degree of the DBW mechanism 62, the valve opening characteristic variable mechanism 50 based on the instantaneous net effective pressure Pmcmdb calculated by the ECU 32. Target phase angle, target lift amount of the EGR control valve 52a, and the like are calculated. At that time, the net average effective pressure Pme may be used.

  FIG. 7 is an explanatory diagram illustrating the processing of FIG.

  Since it is fresh air (air mass flow rate Gair) that can be directly measured as an operation parameter of the engine 10, it is desirable to control the engine 10 on the basis thereof. The fresh air is controlled via the DBW mechanism 62, but if a variation or error occurs between the control and the measured Gir, the fuel amount Gfuel is not calculated correctly. The average effective pressure Pmcmdb) does not match.

  Therefore, in this embodiment, the estimated torque (net average effective pressure Pme) is calculated from the fuel amount Gfuel, the ratio to the required torque (instantaneous net average effective pressure Pmcmdb) is learned, and the correction coefficient Kpmref thus obtained is requested. The correction was made by multiplying the torque.

  Thereby, since it calculates | requires before combustion, even if a combustion state changes with the same air filling amount, it is not influenced by it, but the net average effective pressure Pme can be calculated accurately.

In this embodiment, as described above, the air mass flow rate calculating means (ECU 32, S10) for calculating the air mass flow rate Gair per cycle (one combustion cycle) supplied to the internal combustion engine (engine) 10, the air mass flow rate and the fuel Target equivalent ratio calculation means (ECU32, S12) for calculating a target value (target equivalent ratio) KCMD indicating the ratio of the mass flow rate, and obtained from the calculated air mass flow rate and the target value of the equivalent ratio. Fuel mass flow rate calculation means (ECU 32, S14) that uses the fuel mass flow rate as the fuel mass flow rate Gfuel per cycle to be supplied to the internal combustion engine, and the combustion mode of the internal combustion engine is stratified with the combustion mode by homogeneous mixture flame propagation Which one of the three combustion modes, the combustion mode by mixture flame propagation and the combustion mode by self-ignition, is selected? Another, and work We that can be taken out after searching the cycle by the engine speed and the determined combustion mode of at least the internal combustion engine net thermal efficiency ηe obtained by dividing the quantity of heat Q supplied for said cycle Net heat efficiency calculation means (ECU32, S16) to calculate based on the calorific value Cv obtained from the properties of the fuel to be supplied to the internal combustion engine, the calculated fuel mass flow rate Gfuel and the net heat efficiency ηe, It calculates the brake mean effective pressure (estimated torque) Pme corresponding to the value obtained by dividing the volume of the internal combustion engine, instantly learn the calculated brake mean effective pressure Pme the ratio between the target value Pmcmd Net average effective pressure calculating means (ECU 32, S18 to S24) for calculating the net average effective pressure Pmcmdfb, and the calculated instantaneous Control parameter calculating means for calculating a control parameter of the internal combustion engine based on the brake mean effective pressure (ECU 32, S200) was composed as comprising a.

  Thereby, the net average effective pressure Pme in one combustion cycle can be calculated with high accuracy. That is, since it is obtained before combustion, the net average effective pressure Pme can be accurately calculated without being affected by changes in the combustion state with the same air filling amount.

  In addition, since the actual torque generated by appropriately calculating the control parameter of the engine 10 based on the instantaneous net average effective pressure Pmcmdfb can be matched, the torque variation due to the manufacturing variation of the engine 10 can be absorbed. Thereby, it is possible to reduce the torque fluctuation at the time of combustion switching, and it is possible to improve drivability. In addition, optimum combustion can be performed in the set torque region, unnecessary emission and fuel consumption can be suppressed, and emission performance and fuel consumption performance can be improved.

  Furthermore, since the error between the net average effective pressure Pme required by the engine 10 and the value actually generated can be reduced, the control margin associated with the error can be reduced. As a result, the work amount or capacity of an auxiliary machine such as the oil pump 66 can be reduced, and fuel consumption performance can be improved. In addition, since the net average effective pressure can be calculated with high accuracy without using an expensive in-cylinder pressure sensor, the cost can be reduced.

  Further, the net average effective pressure calculating means learns the calculated net average effective pressure Pme in a ratio with the target value Pmcmd to calculate an average effective pressure correction coefficient Kpmref, and the calculated average effective pressure correction Since the instantaneous net average effective pressure Pmcmdb is calculated on the basis of the coefficient and the target value of the net average effective pressure (ECU 32, S22, S24), the above-described effects can be further improved.

  Further, the net average effective pressure calculating means is configured to stop the learning (ECU 32, S20, S22) when the internal combustion engine is in an operation state that is not stable in combustion. Can be increased.

  In the above, CVT is shown as an example of the automatic transmission 64, and the side pressure is controlled based on the net average effective pressure (estimated torque) or the like. However, instead of CVT, a stepped transmission is provided, The clutch pressure may be controlled based on the average effective pressure (estimated torque) or the like.

1 is a schematic diagram showing an overall control apparatus for an internal combustion engine according to an embodiment of the present invention. It is explanatory drawing which shows control of the combustion mode of the apparatus shown in FIG. It is a flowchart which shows operation | movement of the apparatus shown in FIG. It is a graph which shows the characteristic of a net thermal efficiency used by the process of the flowchart of FIG. FIG. 4 is a flowchart showing processing performed in parallel with the processing of the flowchart of FIG. 3. FIG. Similarly, it is a flowchart showing the process performed in parallel with the process of the flowchart of FIG. It is explanatory drawing explaining operation | movement of this Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine (engine), 16 Throttle valve, 22 Intake valve, 24 Combustion chamber, 26 1st injector, 30 2nd injector, 32 ECU (electronic control unit), 34 Spark plug, 40 Exhaust valve, 50 Valve opening Characteristic variable mechanism, 54 turbocharger, 62 DBW mechanism, 66 oil pump, 72 crank angle sensor, 74 air flow meter, 86 wide area air-fuel ratio sensor, 90 second ECU (electronic control unit)

Claims (3)

An air mass flow rate calculating means for calculating an air mass flow rate per cycle supplied to the internal combustion engine; a target equivalent ratio calculating means for calculating a target value of an equivalence ratio indicating a ratio of the air mass flow rate to the fuel mass flow rate; A fuel mass flow rate calculating means for setting the fuel mass flow rate obtained by calculating from the target value of the air mass flow rate and the equivalence ratio to the fuel mass flow rate per cycle to be supplied to the internal combustion engine, and a combustion mode of the internal combustion engine; It is determined which of the three types of combustion modes, ie, the combustion mode by the homogeneous mixture flame propagation, the combustion mode by the stratified mixture flame propagation and the combustion mode by self-ignition, is selected, and the cycle is taken out once. It is the the rotational speed of at least the internal combustion engine a net thermal efficiency obtained by dividing the amount of heat supplied for the cycle work discrimination that can Net thermal efficiency calculating means for calculating, based on the burn mode, based on the fuel mass flow rate the calculated and the calorific value obtained from the property of the fuel to be supplied to an internal combustion engine and the net thermal efficiency, the work of the internal combustion engine volume The net average effective pressure corresponding to the value obtained by dividing by the above is calculated, and the net average effective pressure is calculated by learning the calculated net average effective pressure in a ratio with the target value and calculating the instantaneous net average effective pressure. A control device for an internal combustion engine, comprising: calculation means; and control parameter calculation means for calculating a control parameter of the internal combustion engine based on the calculated instantaneous net average effective pressure.   The net average effective pressure calculating means learns the calculated net average effective pressure in a ratio with the target value to calculate an average effective pressure correction coefficient, and calculates the calculated average effective pressure correction coefficient and the net average 2. The control apparatus for an internal combustion engine according to claim 1, wherein the instantaneous net average effective pressure is calculated based on a target value of the effective pressure. 3. The control device for an internal combustion engine according to claim 1, wherein the net average effective pressure calculating unit stops the learning when the internal combustion engine is in an operation state that is not stable in combustion.

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