JP2009138590A - Control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of compensating more properly a response delay of a hot wire flow sensor, obtaining accurate detection values corresponding to a change of an engine operating condition, and improving accuracy for controlling a fuel injection amount. <P>SOLUTION: Detection delay of an airflow sensor 11 is compensated in a power WAFM supplied to a hot wire of the sensor 11, and first and second cylinder flowing air flow rates Gaircyl_sum0 and Gaircyl_sum1 are calculated according to the power WAFM before compensated and a compensated power WAFMH (S31, S32). According to an engine operating condition, the first cylinder flowing air flow rate Gaircyl_sum0 or the second cylinder flowing air flow rate Gaircyl_sum1 is selected (S34-S39), and applied for controlling a fuel injection amount and the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that includes a hot-wire flow rate sensor that detects an intake air flow rate.

  Since the response of the detected value is delayed with respect to the change in the flow rate of the hot wire type flow sensor, Patent Document 1 calculates the intake air flow rate of the internal combustion engine by compensating for the response delay, and the calculated intake air flow rate is calculated. A control device for an internal combustion engine adapted for control is shown. According to this control device, the heat transfer type flow sensor is regarded as a first-order lag system, and the inverse transfer function of the transfer function indicating the relationship between the input and the output (detected value) is obtained in advance, and the detected value is applied to the inverse transfer function. Thus, the sensor input, that is, the delay compensated flow rate is calculated.

  Patent Document 2 discloses an improved technique of the technique disclosed in Patent Document 1. That is, a method is shown in which the time constant included in the inverse transfer function is set in accordance with the air flow rate flowing into the engine cylinder, thereby improving the compensation accuracy particularly in a transient operation state.

JP 59-176450 A JP-A-4-116249

  In the method disclosed in Patent Document 1, since delay compensation is performed for the intake air flow rate calculated from the sensor output, when the flow rate change is abrupt, the flow rate obtained using the inverse transfer function is used. Overshooted, and the actual flow rate could deviate significantly. Moreover, even if the technique disclosed in Patent Document 2 is applied, overshoot cannot be sufficiently suppressed. For this reason, the fuel injection amount and the ignition timing become inappropriate, and exhaust characteristics and drivability may be deteriorated.

  The present invention has been made paying attention to this point, and more appropriately compensates for the response delay of the hot-wire flow rate sensor, obtains an accurate detection value corresponding to the change in the engine operating state, and the fuel injection amount, etc. An object of the present invention is to provide a control device for an internal combustion engine that can improve the control accuracy of the engine.

  In order to achieve the above object, the invention according to claim 1 is a hot-wire flow sensor (provided upstream of the throttle valve (3) of the internal combustion engine) for detecting the air flow in the intake pipe (2) of the engine. 11), an intake pressure sensor (12) for detecting an intake pressure (PBA) downstream of the throttle valve of the engine, and the flow rate sensor (11) when the air flow rate changes. Compensation air flow rate calculating means for performing compensation of the temperature change delay of the hot wire with respect to the power (WAFM) supplied to the hot wire, and calculating the compensation air flow rate (Gairth1) according to the delayed power (WAFMH), and the delay Based on the non-compensated air flow rate calculation means for calculating the non-compensated air flow rate (Gairth0) according to the power (WAFM) without compensation, and based on the intake pressure (PBA) detected by the intake pressure sensor. Filling air flow rate calculating means for calculating a filling air flow rate (ΔGB, ΔGB1), which is a change amount of the air amount charged downstream of the throttle valve of the intake pipe, the uncompensated air flow rate (Gairth0) and the charging air flow rate (ΔGB) ) To calculate a non-compensated cylinder inflow air flow rate (Gaircyl_sum0), which is a flow rate of air flowing into the cylinder of the engine, and the compensated air flow rate (Gairth1) and the charge air flow rate (ΔGB1). Compensation cylinder inflow air flow rate calculation means for calculating a compensation cylinder inflow air flow rate (Gaircyl_sum1) that is a flow rate of air flowing into the engine cylinder from the above, and the non-compensation cylinder inflow air according to the operating state of the engine Selecting means for selecting one of a flow rate (Gaircyl_sum0) and a compensation cylinder inflow air flow rate (Gaircyl_sum1), and a cylinder inflow air flow rate (Gaircyl_sum) selected by the selection means sum) is applied to the control of the engine.

  According to a second aspect of the present invention, in the control apparatus for an internal combustion engine according to the first aspect, the selection means performs the selection in accordance with a rotational speed (NE) and a load (TRQ) of the engine. And

  According to a third aspect of the present invention, in the control device for an internal combustion engine according to the first or second aspect, the selection unit includes a transient determination unit that determines whether or not the operation state of the engine is in a transient state. The selection is performed according to the determination result of the transient determination means.

  According to a fourth aspect of the present invention, in the control device for an internal combustion engine according to the third aspect, when the selection means determines that the operating state of the engine is not in a transient state, the uncompensated cylinder inflow air While the flow rate (Gaircyl_sum0) is selected, the compensation cylinder inflow air flow rate (Gaircyl_sum1) is selected when it is determined that the operating state of the engine is in a transient state.

  The charging air flow rate calculation means calculates a smoothed intake pressure by performing a smoothing process of the intake pressure detected by the intake pressure sensor, and uses the smoothed intake pressure to calculate a first charged air flow rate ( First flow rate calculating means for calculating (ΔGB), and second flow rate calculating means for calculating a second charged air flow rate (ΔGB1) using the intake pressure detected by the intake pressure sensor, and the non-compensating cylinder The inflow air flow rate calculation means calculates the uncompensated cylinder inflow air flow rate (Gaircyl_sum0) using the first charge air flow rate (ΔGB), and the compensation cylinder inflow air flow rate calculation means calculates the second charge air flow rate ( It is desirable to calculate the compensation cylinder inflow air flow rate (Gaircyl_sum1) using (ΔGB1).

  According to the first aspect of the present invention, compensation for the temperature change delay of the hot wire of the flow rate sensor when the air flow rate is changed is performed for the power supplied to the hot wire, and the compensated air flow rate is set according to the delayed compensated power. An uncompensated air flow rate that is calculated and not compensated for delay is calculated. Furthermore, a charge air flow rate, which is a change amount of the air amount charged downstream of the throttle valve of the intake pipe, is calculated, and the compensation cylinder inflow air flow rate is calculated using the calculated compensation air flow rate, non-compensation air flow rate, and charge air flow rate The uncompensated cylinder inflow air flow rate is calculated. One of the compensation cylinder inflow air flow rate and the non-compensation cylinder inflow air flow rate is selected according to the engine operating state. Since the air flow rate to be detected is almost proportional to the square of the power supplied to the hot wire, if delay compensation is performed on the detected flow rate as in the conventional method, the effect of the delay in changing the power is effective in the square. Come. For this reason, the error in delay compensation may be very large in the conventional method, but delay compensation with less error can be performed by performing delay compensation at the power stage. Furthermore, by selecting one of the compensated cylinder intake air flow rate and the non-compensated cylinder intake air flow rate according to the engine operating state, a more accurate flow rate can be obtained in both the transient state and the steady state, and the control accuracy can be improved. Can be improved. Particularly in an engine provided with a supercharger, the operation of the supercharger (compressor) may cause pulsation in the output of the flow rate sensor and the accuracy of the detected flow rate may decrease. The decrease in accuracy due to the operation of the machine can be suppressed.

  According to the second aspect of the present invention, the selection before the compensation cylinder intake air flow rate or the non-compensation cylinder intake air flow rate is performed according to the engine speed and the load. For example, in an engine capable of self-ignition combustion, which will be described later, an operation in which the throttle valve is almost fully opened is performed in a predetermined operation region where self-ignition combustion is possible, so that the change in the intake air flow rate becomes relatively small. Accordingly, an accurate flow rate can be obtained by selecting the non-compensated cylinder intake air flow rate in the predetermined operation range set according to the engine speed and the engine load.

  According to the third aspect of the present invention, the selection before the compensated cylinder intake air flow rate or the non-compensated cylinder intake air flow rate is performed according to the determination result of whether or not the engine operating state is in a transient state. Since delay compensation is required when in a transient state, an accurate flow rate can be obtained by making a selection according to the determination result as to whether or not it is in a transient state.

  According to the invention of claim 4, when it is determined that the engine operating state is not in the transient state, the non-compensated cylinder inflow air flow rate is selected, and when it is determined that the engine operating state is in the transient state, the compensated cylinder inflow air flow rate is selected. Is selected, an accurate flow rate can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention. The internal combustion engine (hereinafter simply referred to as “engine”) 1 has an intake pipe 2 and is in the middle of the intake pipe 2. Is provided with a throttle valve 3. The throttle valve 3 is provided with a throttle valve opening sensor 4 for detecting the opening TH of the throttle valve 3, and a detection signal thereof is supplied to an electronic control unit (hereinafter referred to as “ECU”) 5. An actuator 8 that drives the throttle valve 3 is connected to the throttle valve 3, and the operation of the actuator 8 is controlled by the ECU 5.

  The engine 1 includes a first fuel injection valve 6 that injects fuel into the intake pipe 2, a second fuel injection valve 7 that directly injects fuel into the combustion chamber, and a spark plug 9. The first fuel injection valve 6 is provided for each cylinder slightly upstream of an intake valve (not shown). The second fuel injection valve 7 and the spark plug 9 are provided in the combustion chamber of each cylinder. The first and second fuel injection valves 6 and 7 are connected to the ECU 5, and the valve opening timing and valve opening time are controlled by the ECU 5. Similarly, the spark plug 9 is connected to the ECU 5, and the ignition timing is controlled by the ECU 5.

  An air flow sensor 11 for detecting the intake air flow rate is provided on the upstream side of the throttle valve 3 in the intake pipe 2, and a turbocharger compressor 10 is provided between the air flow sensor 11 and the throttle valve 3. . The compressor 10 is connected via a shaft to a turbine (not shown) that is rotationally driven by the energy of the exhaust, and is driven by the turbine.

  An intake pressure sensor 12 for detecting the intake pressure PBA and an intake air temperature sensor 13 for detecting the intake air temperature TA are provided on the downstream side of the throttle valve 3. An engine cooling water temperature sensor 14 for detecting the engine cooling water temperature TW is attached to the main body of the engine 1. Detection signals from these sensors are supplied to the ECU 5.

  The ECU 5 is connected to a crank angle position sensor 15 that detects a rotation angle of a crankshaft (not shown) of the engine 1, and a signal corresponding to the rotation angle of the crankshaft is supplied to the ECU 5. The crank angle position sensor 10 is a cylinder discrimination sensor that outputs a pulse (hereinafter referred to as “CYL pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1, and relates to a top dead center (TDC) at the start of the intake stroke of each cylinder. A TDC sensor that outputs a TDC pulse at a crank angle position before a predetermined crank angle (for example, every 180 degrees in a 4-cylinder engine) and a CRK pulse with a constant crank angle period shorter than the TDC pulse (for example, a period of 30 degrees) It consists of a CRK sensor, and a CYL pulse, a TDC pulse, and a CRK pulse are supplied to the ECU 5. These signal pulses are used for various timing controls such as fuel injection timing and ignition timing, and detection of engine speed (engine speed) NE.

  The ECU 5 is connected to an accelerator sensor 16 for detecting an accelerator pedal depression amount (hereinafter referred to as “accelerator pedal operation amount”) AP of the vehicle driven by the engine 1, and the detection signal is supplied to the ECU 5. .

  The ECU 5 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, etc., and a central processing unit (hereinafter referred to as “CPU”). In addition to a storage circuit that stores a calculation program executed by the CPU, a calculation result, and the like, an output circuit that supplies a drive signal to the actuator 8, the fuel injection valves 6 and 7, and the spark plug 9 is provided.

  The ECU 5 controls the valve opening time of the fuel injection valves 6 and 7 based on detection signals from various sensors. At that time, as described below, an intake air flow rate calculation process including a delay compensation process for the output voltage VAFM of the air flow sensor 11 is performed.

  In the present embodiment, the combustion mode is switched in the combustion chamber of the engine 1 so that combustion is performed in the first to third combustion modes. In the first combustion mode, fuel injection is performed only by the first fuel injection valve 6, in the second combustion mode, fuel injection is performed only by the second fuel injection valve 7, and in the third combustion mode, the first and second fuel injections are performed. Two fuel injections are performed by the second fuel injection valves 6 and 7. The first combustion mode is selected when the opening degree of the throttle valve 3 is controlled to be relatively low, and the second combustion mode is selected when the throttle valve 3 is fully closed. The combustion mode is selected in cases other than the above. In any combustion mode, ignition by the spark plug 9 is performed. In the second combustion mode, the stratified mixture is formed so that ignition can be performed (self-ignition is possible) without performing ignition by the ignition plug 9, but ignition by the ignition plug 9 is performed in order to obtain reliable ignition. . In the third combustion mode (two-injection combustion mode), when the engine load is relatively low, self-ignition is possible as in the second combustion mode (however, ignition by the spark plug 9 is performed to ensure ignition). )

FIG. 2 is a circuit diagram showing the configuration of the airflow sensor 11, and the airflow sensor 11 includes resistors 21 to 23 that constitute a Wheatstone bridge circuit, and a compensator 25. The resistor 21 corresponds to a heat ray exposed in the intake pipe 2, and the compensator 25 adjusts the output voltage VAFM so that the resistance value R of the resistor 21 is constant. Specifically, the output voltage (voltage between the contacts ac) VAFM is adjusted so that the voltage between the contacts bd becomes “0”. Since the resistance value R varies depending on the temperature of the resistor 21, the temperature of the resistor 21 is controlled to be constant by controlling the resistance value R to be constant. Assuming that the current flowing through the resistor 21 is I, it is known that the relationship of the following formula (1) is established.
I ² × R = A + B × U ^0.5 (1)
Here, U is the mass flow rate of the gas flowing in the vicinity of the resistor 21, and A and B are constants.

The current I is expressed by the following formula (2) using the output voltage VAFM.
I = VAFM / (R + r) (2)

The following formula (3) is obtained from the formulas (1) and (2), and the flow rate U is given by the following formula (4) by modifying the formula (3). Further, since the left side of the formula (1) is the power WAFM consumed by the resistor 21, the flow rate U is given by the following formula (5) when the power WAFM is used.

  As apparent from the above equations (4) and (5), the flow rate U is approximately proportional to the fourth power of the output voltage VAFM and proportional to the square of the power WAFM. Therefore, the calculation of the sensor delay compensation can be performed with less error by performing the calculation for the power WAFM or the output voltage VAFM than for the flow rate U. In the present embodiment, as described below, a delay compensation calculation is performed on the power WAFM, and a delay-compensated intake air flow rate (compensated intake air flow rate) is calculated according to the delay-compensated power WAFMH. ing. In the present embodiment, an intake air flow rate (non-compensated intake air flow rate) that is not compensated for delay is also calculated according to the power WAFM for which delay compensation calculation is not performed, and the compensated intake air flow rate or non-compensated intake air flow is determined according to the engine operating state. The flow rate is selected.

  FIG. 3 is a flowchart of a process for calculating the amount of air per unit time (cylinder inflow air flow rate) flowing into the cylinder of the engine 1 according to the output voltage VAFM of the air flow sensor 11. This process is executed by the CPU of the ECU 5 every predetermined time (for example, 1 millisecond). The parameter k used in this process is a discretization time discretized in the execution cycle of this process.

  In step S11, the output voltage VAFM is read. In step S12, the output voltage VPBA of the intake pressure sensor 12 is read. In step S13, the power consumption WAFM of the resistor 21 (heat wire) is calculated from the output voltage VAFM, and in step S14, the voltage VPBA is converted into the intake pressure (absolute pressure) PBA.

  In step S15, the power consumption WAFM is applied to the equation (5) to calculate the first throttle valve passing air flow rate Gairth0 (U in equation (5) corresponds to Gairth0, unit [g / sec]).

In step S16, the previous intake air pressure value PBA (k-1) detected in the following equation (6) is applied to calculate the smoothed intake air pressure PBD (k).
PBD (k) = a * PB (k-1) + (1-a) * PBD (k-1) (6)
Here, a is a smoothing coefficient set to a value between 0 and 1, and is set to the same value as the delay compensation parameter b described below, for example.

In step S17, the current value and the previous value of the smoothed intake pressure PBD, and the intake air temperature TA (absolute temperature converted value) are applied to the following equation (7), and the first intake air that is the intake pipe filling air amount per unit time is applied. The pipe filling air flow rate ΔGB [g / sec] is calculated. In a steady engine operation state, the smoothed intake pressure PBD is applied to match the intake pipe filling air flow rate with the responsiveness of the air flow sensor 11.
ΔGB = (PBD (k) −PBD (k−1)) × VOLIN / (RG × TA) (7)

  Here, VOLIN is the volume of the intake pipe (downstream part of the throttle valve 3), and RG is a gas constant.

In step S18, the first throttle valve passage air flow rate Gairth0 and the first intake pipe charging air flow rate ΔGB are applied to the following equation (8) to calculate the first cylinder inflow air flow rate Gaircyl_T0.
Gaircyl_T0 (k) = Gairth0−ΔGB (8)

In step S19, the current value and the previous value of the intake pressure PBA, and the intake air temperature TA (absolute temperature conversion value) are applied to the following equation (9) to fill the second intake pipe filling air amount per unit time. The air flow rate ΔGB1 [g / sec] is calculated.
ΔGB1 = (PBA (k) −PBA (k−1)) × VOLIN / (RG × TA)
(9)

In step S20, the current value WAFM (k) and the previous value WAFM (k-1) of power consumption calculated in step S13 are applied to the following equation (10) to calculate the current value WAFMH (k) of delay compensation power. To do.
WAFMH (k) = (WAFM (k) − (1−b) × WAFM (k−1)) / b
(10)

  Here, b is a delay compensation parameter determined based on the sampling period. Specifically, 100 times the sampling period (seconds) is set as the delay compensation parameter b. For example, when the sampling period is 1 msec, b = 0.1.

  In step S21, the delay compensation power WAFMH calculated in step S20 is applied to the equation (5), and the second throttle valve passage air flow rate Gairth1 (U in equation (5) corresponds to Gairth1, unit [g / sec]). ) Is calculated.

In step S22, the second throttle valve passing air flow rate Gairth1 and the second intake pipe charging air flow rate ΔGB1 are applied to the following equation (11) to calculate the cylinder inflow air flow rate Gaircyl_T1 (k) [g / sec].
Gaircyl_T1 (k) = Gairth1-ΔGB1 (11)

  In step S23, the discretization time k is incremented by “1”, and this process is terminated.

  FIG. 4 shows the first and second cylinder inflow air flows Gaircyl_T0 (k) and Gaircyl_T1 (k) calculated in the process of FIG. 3, and the cylinder inflow air flows Gaircyl_sum0 and Gaircyl_sum1 per 1 TDC period (TDC pulse generation cycle). 6 is a flowchart of a process for converting to a final cylinder inflow air flow rate Gaircyl_sum. This process is executed by the CPU of the ECU 5 in synchronization with the generation of the TDC pulse.

In step S31, the first cylinder inflow air flow rate Gaircyl_T0 (k) is applied to the following equation (12) to calculate the first cylinder inflow air flow rate Gaircyl_sum0 in the TDC cycle. ΔT in Expression (12) is an execution cycle of the process of FIG. 3, that is, a calculation cycle of the cylinder inflow air flow rate Gaircyl_T0 (k).

ステップＳ３３では、離散化時刻ｋを「０」に戻す。 In step S32, the second cylinder inflow air flow rate Gaircyl_T1 (k) is applied to the following equation (13) to calculate the second cylinder inflow air flow rate Gaircyl_sum1 of the TDC cycle.

In step S33, the discretization time k is returned to "0".

  In step S34, the driving | running state determination process shown in FIG. 5 is performed. In step S41 of FIG. 5, it is determined whether or not the engine cooling water temperature TW is higher than a predetermined water temperature TWHCI (for example, 85 ° C.). If the answer is affirmative (YES), the engine speed NE and the engine required torque TRQ are determined. It is determined whether or not the operating point determined by is within a predetermined area RSI indicated by hatching in FIG. 6B (step S42). The required torque TRQ is calculated according to the engine speed NE and the accelerator pedal operation amount AP, and the required torque TRQ increases as the accelerator pedal operation amount AP increases. The predetermined region RSI shown in FIG. 6B corresponds to the above-described operation region where self-ignition is possible. In the predetermined region RSI, the air-fuel ratio of the air-fuel mixture in the combustion chamber is controlled to be leaner than the stoichiometric air-fuel ratio, and the throttle valve 3 is controlled to be almost fully open. In regions other than the predetermined region RSI, the air-fuel ratio is controlled to be the stoichiometric air-fuel ratio.

  When the answer to steps S41 and S42 is both affirmative (YES), the self-ignition mode flag FHCCI is set to “1” (step S43), and when the answer to step S41 or S42 is negative (NO), The self-ignition mode flag FHCCI is set to “0” (step S44).

  Returning to FIG. 4, in step S <b> 35, it is determined whether or not the self-ignition mode flag FHCCI is “1”. If this answer is affirmative (YES), that is, if the engine operating state is a state in which self-ignition is possible, the final cylinder inflow air flow rate Gaircyl_sum is set to the first cylinder inflow air flow rate Gaircyl_sum0 (step S39). When the engine operating state is in the predetermined region RSI shown in FIG. 6B, the throttle valve 3 is controlled to be in a fully open state, so that the change in the intake air flow rate is small. Therefore, the first cylinder inflow air flow rate Gaircyl_sum0 without delay compensation is employed.

If FHCCI = 0 in step S35, the intake pressure change amount ΔPBT is calculated by the following equation (14) (step S36).
ΔPBT = PBA (n) −PBA (n−1) (14)
Here, “n” is a discretization time discretized in the execution cycle (TDC pulse generation cycle) of this process.

  In step S37, a CGAIRCYL table shown in FIG. 6A is retrieved according to the intake pressure change amount ΔPBT, and a switching coefficient CGAIRCYL is calculated. In the CGAIRCYL table, when the intake pressure change amount ΔPBT is in the range from the first predetermined value ΔP1M to the second predetermined value ΔP1P, the switching coefficient CGAIRCYL becomes “0”, and the intake pressure change amount ΔPBT is equal to or less than the third predetermined value ΔP2M. Is equal to or greater than the fourth predetermined value ΔP2P, the switching coefficient CGAIRCYL is “1”, and when the intake pressure change amount ΔPBT is greater than the third predetermined value ΔP2M and smaller than the first predetermined value ΔP1M, the intake pressure As the change amount ΔPBT increases, the switching coefficient CGAIRCYL decreases. When the intake pressure change amount ΔPBT is larger than the second predetermined value ΔP1P and smaller than the fourth predetermined value ΔP2P, the switching coefficient CGAIRCYL increases as the intake pressure change amount ΔPBT increases. It is set to increase.

  In the CGAIRCYL table, as shown in FIG. 6A, it is desirable to gradually change the switching coefficient CGAIRCYL from “0” to “1” or vice versa, but as shown in FIG. It may be set.

In step S38, the final cylinder inflow air flow rate Gaircyl_sum is calculated by applying the first and second cylinder intake air flow rates Gaircyl_sum0 and Gaircyl_sum1 and the switching coefficient CGAIRCYL to the following equation (15).
Gaircyl_sum = (1-CGAIRCYL) × Gaircyl_sum0
+ CGAIRCYL × Gaircyl_sum1 (15)

  In steps S36 to S38, when the absolute value of the intake pressure change amount ΔPBT is relatively small (ΔP1M ≦ ΔPBT ≦ ΔP1P) and the engine operating state is in a steady state, the final cylinder inflow air flow rate Gaircyl_sum is When the first cylinder inflow air flow rate Gaircyl_sum0 for which detection delay compensation is not performed is set, the absolute value of the intake pressure change amount ΔPBT is relatively large (ΔPBT ≦ ΔP2M or ΔPBT ≧ ΔP2P), and is in a transient state. The final cylinder inflow air flow rate Gaircyl_sum is set to the second cylinder inflow air flow rate Gaircyl_sum1 for which detection delay compensation is performed. The influence of the detection delay appears prominently in the transient state, so that an accurate cylinder inflow air flow rate can be obtained by selecting the first cylinder inflow air flow rate Gaircyl_sum0 and the second cylinder inflow air flow rate Gaircyl_sum1 according to the switching coefficient CGAIRCYL. Can do. As a result, the control accuracy of the fuel injection amount and the ignition timing can be improved.

  Moreover, it can suppress that the precision of a cylinder inflow air flow rate falls by the pulsation to the output voltage VAFM of the airflow sensor 11 resulting from the action | operation of a supercharger (compressor 10).

  Further, in the predetermined region RSI shown in FIG. 6, since the operation is performed with the throttle valve almost fully open, the change in the intake air flow rate becomes relatively small. Therefore, in the predetermined region RSI, an accurate flow rate can be obtained by selecting the first cylinder inflow air flow rate Gaircyl_sum0 for which delay compensation is not performed.

  Further, in the process of FIG. 3, the delay compensation power WAFMH is calculated by executing a delay compensation calculation for the power WAFM consumed by the hot wire (resistor 21) of the airflow sensor 11, and the throttle valve passing air flow rate is calculated from the delay compensation power WAFMH. Since Gairth is calculated, delay compensation with less error can be performed and accurate cylinder inflow air flow rate can be obtained as compared with the case where delay compensation is performed for the detected flow rate as in the conventional method.

  FIG. 7 is a time chart for explaining the effect of delay compensation in the present embodiment. The solid line L1 indicates the throttle valve passage air flow rate compensated for delay by the method of the present embodiment, the broken line L2 indicates the throttle valve passage air flow rate compensated for delay by the conventional method, and the alternate long and short dash line L3 performs delay compensation. Indicates the flow rate of air that has not passed through the throttle valve. In the conventional method, underflow occurs due to overcompensation in the process of abruptly decreasing the air flow rate (A part in FIG. 7). However, in the method of this embodiment, such an underflow is prevented. Can do.

  In the present embodiment, the air flow sensor 11 corresponds to a hot-wire flow rate sensor, and the ECU 5 performs compensation air flow rate calculation means, non-compensation air flow rate calculation means, filling air flow rate calculation means, non-compensation cylinder inflow air flow rate calculation means, compensation cylinder. An inflow air flow rate calculation unit, a selection unit, a transient determination unit, a first flow rate calculation unit, and a second flow rate calculation unit are configured. Specifically, steps S20 and S21 in FIG. 3 correspond to the compensation air flow rate calculation means, S15 corresponds to the non-compensation air flow rate calculation means, and steps S17 and S19 correspond to the charge air flow rate calculation means. Step S18 of FIG. 4 and Step S31 of FIG. 4 correspond to the non-compensated cylinder inflow air flow rate calculation means, Step S22 of FIG. 3 and Step S32 of FIG. 4 correspond to the compensation cylinder inflow air flow rate calculation means, and Step S34 of FIG. To S39 correspond to selection means. Steps S36 and S37 in FIG. 4 correspond to the transient determination means.

The present invention is not limited to the embodiment described above, and various modifications can be made. For example, the TDC process of FIG. 8 may be applied instead of the TDC process shown in FIG. The process of FIG. 8 is obtained by deleting steps S36 to S38 of FIG. 4 and adding step S40. In step S40, the final cylinder inflow air flow rate Gaircyl_sum is set to the second cylinder inflow air flow rate Gaircyl_sum1. Therefore, in the process of FIG. 8, selection according to the intake pressure change amount ΔPBT is not performed, and the first cylinder inflow air flow rate Gaircyl_sum0 or the second cylinder inflow air flow rate Gaircyl_sum1 is selected according to the value of the self-ignition mode flag FHCCI. The
Further, in the above-described embodiment, an example in which the present invention is applied to an engine capable of self-ignition combustion in the predetermined operation region RSI of the engine 1 is shown. However, when such self-ignition combustion operation is not performed, FIG. The TDC process shown in FIG. 9 is applied instead of the TDC process shown. FIG. 9 is obtained by deleting steps S34, S35, and S39 of FIG.

  In the above-described embodiment, the present invention is applied to an engine having two fuel injection valves. However, only one of a fuel injection valve that injects fuel into the intake pipe and a fuel injection valve that injects fuel into the combustion chamber is provided. The present invention can also be applied to an engine provided.

  In the above-described embodiment, the transient state is determined based on the intake pressure change amount ΔPBT. However, the present invention is not limited to this. For example, the change amount of the accelerator pedal operation amount AP and the change amount of the required torque TRQ, Alternatively, the determination may be made based on the deviation between the required torque TRQ and the actual output torque of the engine. In either case, it is determined that the engine operating state is in a transient state when the amount of change or the deviation is greater than or equal to a predetermined value.

  The present invention can also be applied to control of a marine vessel propulsion engine such as an outboard motor having a crankshaft as a vertical direction.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a circuit diagram which shows the structure of an airflow sensor. It is a flowchart of the process which calculates the cylinder inflow air amount (Gaircyl_T0 (k), Gaircyl_T1 (k)) per unit time according to an airflow sensor output (VAFM). It is a flowchart of the process which calculates the final cylinder inflow air flow volume (Gaircyl_sum) according to the cylinder inflow air amount (Gaircyl_T0 (k), Gaircyl_T1 (k)) per unit time calculated by the process of FIG. It is a flowchart of the driving | running state determination process performed by the process of FIG. It is a figure which shows the table and map referred by the process of FIG. 4 or FIG. It is a time chart for demonstrating the effect of the delay compensation in this embodiment. It is a flowchart which shows the modification of the process of FIG. It is a flowchart which shows the other modification of the process of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 5 Electronic control unit (Compensation air flow rate calculation means, Non-compensation air flow rate calculation means, Filling air flow rate calculation means, Non-compensation cylinder inflow air flow rate calculation means, Compensation cylinder inflow air flow rate calculation means, Selection means, (Transient determination means, first flow rate calculation means, second flow rate calculation means)
11 Air flow sensor (hot wire flow sensor)

Claims (4)

In a control device for an internal combustion engine provided with a hot wire flow rate sensor that is provided upstream of a throttle valve of the internal combustion engine and detects an air flow rate in an intake pipe of the engine,
An intake pressure sensor for detecting an intake pressure downstream of the engine throttle valve;
Compensation air flow rate calculation means for performing compensation for the temperature change delay of the hot wire of the flow rate sensor when the air flow rate is changed, for the power supplied to the heat wire, and calculating a compensation air flow rate according to the delay compensated power,
A non-compensated air flow rate calculating means for calculating a non-compensated air flow rate according to the electric power not performing the delay compensation;
A charge air flow rate calculating means for calculating a charge air flow rate that is a change amount of the air amount charged downstream of the throttle valve of the intake pipe based on the intake pressure detected by the intake pressure sensor;
Uncompensated cylinder inflow air flow rate calculating means for calculating an uncompensated cylinder inflow air flow rate that is a flow rate of air flowing into the cylinder of the engine from the uncompensated air flow rate and the charge air flow rate;
Compensation cylinder inflow air flow rate calculating means for calculating a compensation cylinder inflow air flow rate that is a flow rate of air flowing into the cylinder of the engine from the compensation air flow rate and the charge air flow rate;
Selecting means for selecting one of the non-compensating cylinder inflow air flow rate and the compensation cylinder inflow air flow rate according to the operating state of the engine;
A control apparatus for an internal combustion engine, wherein the cylinder inflow air flow rate selected by the selection means is applied to control of the engine.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the selection means performs the selection according to a rotation speed and a load of the engine.   The selection unit includes a transient determination unit that determines whether or not the operating state of the engine is in a transient state, and performs the selection according to a determination result of the transient determination unit. 3. The control device for an internal combustion engine according to 2.   The selection means selects the non-compensated cylinder inflow air flow rate when it is determined that the operating state of the engine is not in a transient state, while when the operating state of the engine is determined to be in a transient state 4. The control apparatus for an internal combustion engine according to claim 3, wherein the compensation cylinder inflow air flow rate is selected.

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