JP2014214618A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of rapidly and correctly estimating atmospheric pressure without providing an atmospheric pressure sensor.SOLUTION: A control device for an internal combustion engine includes: a target effective opening area calculating means for calculating a target effective opening area of a throttle opening control means by applying an estimated atmospheric pressure, a target intake air flow rate, an intake air pressure and an intake air temperature to a flow rate formula for a throttle flow meter; a target opening calculating means for calculating a target throttle opening from the target effective opening area by using a correlation map between an effective opening area of the throttle opening control means and a throttle opening adapted in advance; and an estimated atmospheric pressure updating means for updating the estimated atmospheric pressure so that an actual intake air flow rate is coincident with the target intake air flow rate.

Description

  The present invention relates to a control device for an internal combustion engine that estimates an atmospheric pressure applied to calculation of a control parameter of the internal combustion engine.

  In recent years, an engine control method called “torque-based control” that controls engine generated torque using an engine output shaft torque, which is a physical quantity directly acting on vehicle control, as an index has become widespread. In such torque-based control, the engine target torque is determined based on the amount of operation of the accelerator pedal by the driver, and the throttle opening is set so that the target intake air flow rate that can generate this target torque is sucked into the engine. By controlling the ignition coil at the ignition timing at which the target torque is realized by the actual intake air flow rate detected by the sensor or the estimated intake air flow rate, the engine output is controlled to the target torque and the driver's The required running performance will be realized.

In order to realize such a target intake air flow rate corresponding to the target torque of the engine, in an internal combustion engine control device that controls the throttle opening by driving an actuator connected to the throttle of the engine, the differential pressure before and after the throttle Means have been proposed in which the target opening area of the throttle is determined by applying to the flow rate equation of the orifice based on the air flow area and the flow coefficient, and the throttle opening is set to achieve the throttle target opening area.
However, in order to calculate the throttle opening that achieves the target intake air flow rate by applying it to the orifice flow rate equation, data such as atmospheric pressure, intake pressure, and intake air temperature are required. It is necessary to install a sensor. However, since the cost increases by attaching various sensors, a method for estimating the atmospheric pressure without using the atmospheric pressure sensor among the various sensors has been proposed.

  As a method for estimating the atmospheric pressure without using such an atmospheric pressure sensor, there is known a method for estimating the atmospheric pressure at the time of start and when the running throttle is fully opened. In an apparatus using such a method, The throttle may not be fully opened depending on the driving state of the driver, and there is a problem that data is not updated from the atmospheric pressure estimated at the time of starting. In response to this problem, Patent Document 1 discloses a method for estimating the atmospheric pressure from the intake pressure, the intake air temperature, the intake air amount, and the throttle opening in an operation state in which the vehicle speed is equal to or higher than a predetermined value.

  According to this atmospheric pressure estimation method, the opening area is obtained from a preset opening area map in accordance with the throttle opening, and is set in advance based on the pressure ratio between the detected intake pressure and the estimated atmospheric pressure. The pressure ratio flow function value is obtained from the pressure ratio flow function, the preset intake air temperature parameter is obtained from the detected intake air temperature, and the estimated throttle valve passing air flow rate is calculated by multiplying them, and this estimated throttle AFS correction estimated throttle valve passing air flow rate is calculated by correcting the valve passing air flow rate by the detection delay of an air flow sensor (hereinafter referred to as AFS), and this AFS correction estimated throttle valve passing air flow rate is detected by AFS. The atmospheric pressure is estimated by updating the estimated atmospheric pressure so as to coincide with the intake air flow rate.

International Patent Publication No. WO2010 / 090060A1

  However, in the method disclosed in Patent Document 1, since the atmospheric pressure is generally low and the air density is low at high altitudes, correction by the atmospheric pressure is necessary to increase the intake air flow rate. Since the atmospheric pressure is updated, the intake air flow rate is corrected by the atmospheric pressure, and the throttle operates. Therefore, both the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate change.

  Further, in order to make the estimated throttle valve passage air flow rate equivalent to the intake air flow rate, correction based on AFS detection delay is performed, and it is necessary to set the flow detection delay characteristic of AFS based on experiments. For this setting, it is necessary to set the estimated throttle valve passage air flow rate obtained by theoretical calculation from the intake air flow rate output by the AFS by the throttle operation in each operation state so as to correspond to the intake air flow rate. Correction may be inappropriate depending on variations in sensors and intake systems. In this case, the responsiveness of the air flow rate passing through the AFS correction estimated throttle valve is deteriorated, and it is necessary to set a sufficient time for stabilization. Therefore, the update period of the estimated atmospheric pressure is delayed, and it takes time to converge. It will end up.

FIG. 7A shows a time chart when the time until the correction is stabilized is sufficiently set.
At t1, the atmospheric pressure estimation is updated because there is a difference between the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate. By updating the atmospheric pressure estimation, the intake air flow rate changes as described above, and the AFS correction estimated throttle valve passage air flow rate also changes.
Until the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate become stable, it is a transient change, and it is easy to erroneously estimate the atmospheric pressure. Therefore, until the intake air flow rate and the AFS correction estimation throttle valve passage air flow rate become stable. It is necessary to set a sufficient time for this, and during this time, the update of the atmospheric pressure estimation is stopped.
At t2, it is determined that the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate are stable, and the atmospheric pressure estimation is updated because there is a difference between the intake air flow rate and the AFS correction estimation throttle valve passage air flow rate. During the period from t1 to t2, the update of the atmospheric pressure estimation is stopped. As in the case of t1 to t2, the atmospheric pressure estimation is updated until the AFS correction estimated throttle valve passage air flow rate matches the intake air flow rate at t4, and there is a problem that it takes time to converge.

FIG. 7B shows a time chart when the update period of the estimated atmospheric pressure is shortened.
At t1, the atmospheric pressure estimation is updated because there is a difference between the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate. By updating the atmospheric pressure estimation, the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate change.
If the update period of the estimated atmospheric pressure is short at t2, the estimated atmospheric pressure is updated before the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate are stabilized.
At t3, the estimated atmospheric pressure matches the actual atmospheric pressure, but since the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate are not stable, a difference occurs and the estimated atmospheric pressure is updated. . For this reason, the estimated atmospheric pressure will overshoot.

At t4, the estimated AFS correction estimated throttle valve passage air flow rate is updated to be lower than the estimated atmospheric pressure when the intake air flow rate becomes larger. However, the AFS correction estimated throttle valve passage air flow rate is corrected by the detection delay of the AFS. It does not respond immediately because it does, and operates to rise.
Also at t5, the estimated atmospheric pressure is updated so as to decrease similarly to t4, and the AFS correction estimated throttle valve passage air flow rate changes.
At t6, the estimated atmospheric pressure approaches the actual atmospheric pressure, but since the response of the AFS correction estimated throttle valve passage air flow rate is slow, a difference from the intake air flow rate occurs, and the estimated atmospheric pressure is updated.

  As described above, according to the conventional atmospheric pressure estimation method, the estimated atmospheric pressure overshoots the actual atmospheric pressure due to the response delay between the intake air flow rate and the AFS correction estimated throttle valve passage air flow rate. When the flow rate is smaller than the AFS correction estimated throttle valve passage air flow rate, there is a problem that undershoot occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can estimate atmospheric pressure quickly and without error.

An internal combustion engine control apparatus according to the present invention includes:
In a control apparatus for an internal combustion engine comprising atmospheric pressure estimation means for estimating an atmospheric pressure to be applied to calculation of a control parameter of the internal combustion engine,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Target intake air flow rate calculating means for calculating a target intake air flow rate based on the operating state of the internal combustion engine;
A throttle provided in the intake passage of the internal combustion engine;
Throttle opening control means for changing the effective opening area of the intake passage by controlling the throttle opening of the throttle, and variably controlling the intake amount to the internal combustion engine;
An actual intake air flow rate detecting means for detecting an actual intake air flow rate to the internal combustion engine;
Intake pressure detection means for detecting the pressure on the internal combustion engine side of the throttle as intake pressure;
An intake air temperature detecting means for detecting an intake air temperature on the atmosphere side of the throttle,
The atmospheric pressure estimating means includes
Applying the estimated atmospheric pressure, the target intake air flow rate, the intake pressure and the intake air temperature to the flow rate calculation formula of the throttle type flow meter to calculate the target effective opening area of the throttle opening control means Opening area calculating means;
A target opening calculation means for calculating a target throttle opening from the target effective opening area, using a correspondence map between the effective opening area of the throttle opening control means and the throttle opening adapted in advance;
Estimated atmospheric pressure update means for updating the estimated atmospheric pressure so that the actual intake air flow rate matches the target intake air flow rate,
The target opening calculation means is configured to calculate the target throttle opening using the estimated atmospheric pressure updated by the estimated atmospheric pressure updating means, and to control the throttle opening to the target throttle opening. Is.

  According to the present invention, the target intake air flow rate calculated based on the operation state does not include correction due to a response delay of the sensor, and the atmospheric pressure is estimated so that the actual intake air flow rate matches the target intake air flow rate. By doing so, the atmospheric pressure can be estimated early and with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a main configuration of a vehicle to which an internal combustion engine control device according to Embodiment 1 of the present invention is applied. It is a block diagram which shows the electric system of the engine control part which concerns on Embodiment 1 of this invention. It is a functional block diagram for demonstrating the atmospheric pressure estimation method which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the map data of dimensionless flow volume (sigma) based on Embodiment 1 of this invention. It is a flowchart which shows the atmospheric pressure estimation processing procedure which concerns on Embodiment 1 of this invention. It is a time chart explaining the operation | movement state of the atmospheric pressure estimation process which concerns on embodiment of this invention. It is a time chart explaining the operation state of atmospheric pressure presumption processing in the conventional device.

Embodiment 1 FIG.
Hereinafter, the present invention will be described in detail with reference to the drawings which are embodiments.
FIG. 1 is a schematic diagram showing a main configuration of a vehicle to which a control device for an internal combustion engine according to Embodiment 1 of the present invention is applied.

In FIG. 1, an engine main body 1 constituting an internal combustion engine is provided with an intake pipe 2 for sucking air and an exhaust pipe 3 for discharging exhaust gas. An airflow sensor (AFS) 4 that measures the actual intake air flow rate supplied to the engine body 1 is provided upstream of the intake pipe 2, and an intake air temperature sensor 5 that detects the intake air temperature integrally with the AFS 4 or separately. Is provided.
Further, on the downstream side of the AFS 4, there is provided a throttle 7 that can arbitrarily adjust the opening according to the opening indicated by the accelerator opening sensor 6 provided in the accelerator pedal. A throttle opening sensor 8 for detecting the throttle opening position is provided.

  Further, a pressure sensor 10 that detects the intake pressure in the surge tank 9 and the intake pipe 2 is provided on the downstream side of the throttle 7. The pressure sensor 10 can also use means for calculating and estimating the intake pressure based on other sensor information.

  The engine body 1 is also provided with a rotation speed sensor 11 that detects the engine speed (engine rotation speed), an injector 13 that injects fuel into the engine body 1, and an ignition coil 14 that ignites the fuel. .

Detection signals from the above-described various sensors and other sensors (not shown) are input to an electronic control unit (hereinafter referred to as ECU) 12 composed of a microcomputer as information indicating the operating state of the engine body 1. The target torque is calculated from the various input data, the target intake air flow rate that achieves this target torque is calculated, and the target effective opening area is calculated by the method described later so as to achieve the target intake air flow rate. The degree of opening is determined, and the opening degree of the throttle 7 is controlled so as to achieve the target throttle opening degree.
At the same time, command values for controlling various actuators including the injector 13 and the ignition coil 14 are also calculated and output.
Further, the ECU 12 executes an atmospheric pressure estimation process for estimating the atmospheric pressure as will be described later, and corrects the target effective opening area based on the obtained estimated atmospheric pressure.

FIG. 2 is a block diagram showing an electrical system of an engine control unit in the control device for the internal combustion engine shown in FIG.
In the figure, the ECU 12 includes an input interface (hereinafter referred to as “input I / F”) 12a, an arithmetic processing unit 12b, and an output interface (hereinafter referred to as “output I / F”) 12c. The / F12a is connected to various sensors 30 including an AFS 4, an intake air temperature sensor 5, an accelerator opening sensor 6, a throttle opening sensor 8, a pressure sensor 10, and other sensors (not shown).

The arithmetic processing unit 12b in the ECU 12 first calculates a target torque of the engine body 1 based on various input data (operating state), and calculates a target intake air flow rate for achieving the target torque. .
Subsequently, the arithmetic processing unit 12b sets the torque required by the driver from the operating state of the engine (driver required torque), the load torque (loss torque) due to operation of the engine, and the engine rotation as the target engine rotation during idling. The target torque is calculated from the total of the torques adjusted in this way (ISC torque), the target torque is converted into the target intake air flow rate, the target effective opening area for achieving the target intake air flow rate is calculated, and the target A target throttle opening for achieving an effective opening area is calculated.
Further, the arithmetic processing unit 12b calculates various control command values and outputs them to various actuators 40 including the throttle 7, the injector 13, and the ignition coil 14 via the output I / F 12c. As a result, the throttle 7 is controlled so that the throttle opening coincides with the target throttle opening.

FIG. 3 is a functional block diagram for explaining a method of calculating the estimated atmospheric pressure performed in the ECU 12 in order to make the actual intake air flow rate coincide with the target intake air flow rate.
In the figure, the driver request torque calculation means 50 calculates the torque required by the driver according to the driving state input from the various sensors 30.
The loss torque calculating means 51 obtains, as a friction load, a pumping load generated by the intake and exhaust of the engine and a frictional resistance caused by the friction generated by the operation of the engine as a friction load depending on the operation state input from the various sensors 30. The sum of the load and friction load is calculated as loss torque.

  The ISC torque calculation means 52 adjusts the torque so that the engine rotation becomes the target engine rotation at the time of idling according to the operation state input from the various sensors 30, and calculates the ISC (idle rotation speed control) torque.

The charging efficiency conversion unit 53 converts the total torque (target torque) output from the driver required torque calculation unit 50, the loss torque calculation unit 51 and the ISC torque calculation unit 52 into a charging efficiency representing the engine load.
The target intake / intake amount calculating means calculates a target intake air flow rate Qa * for achieving the target torque from the charging efficiency output by the charging efficiency converting means 53, and the target effective opening area calculating means 15 and the estimated atmospheric pressure updating means. 16 is output.

The estimated atmospheric pressure update means 16 receives the actual intake air flow rate Qa detected by the AFS 4 and calculates the estimated atmospheric pressure GPo so that the actual intake air flow rate Qa matches the target intake air flow rate Qa *. The estimated atmospheric pressure GPo is input to the pressure ratio calculation means 17 as the atmospheric pressure Po.
The pressure ratio calculation means 17 comprises a divider for calculating the pressure ratio Pe / Po between the intake pressure Pe and the atmospheric pressure Po input from the pressure sensor 10, and the calculated value of the pressure ratio Pe / Po is a dimensionless flow rate calculation means. 18
The dimensionless flow rate calculation means 18 calculates a dimensionless flow rate σ based on the pressure ratio Pe / Po and inputs it to the target effective opening area calculation means 15.
The sonic speed calculating means 20 calculates the sonic speed a ₀ in the atmosphere based on the intake air temperature To detected from the intake air temperature sensor 5 and inputs it to the target effective opening area calculating means 15.

The target effective opening area calculating means 15 calculates the target effective opening area CAt * of the throttle 7 using the target intake air flow rate Qa *, the sonic speed a ₀ and the dimensionless flow rate σ as input information and inputs the target effective opening area CAt * to the target opening degree calculating means 19. To do.
The target opening calculation means 19 uses a pre-adapted correspondence map between the effective opening area CAt and the throttle opening TP (hereinafter referred to as “CAt-TP map”), and the target opening corresponding to the target effective opening area CAt *. The degree TP * is calculated and the opening degree of the throttle 7 is controlled.

Next, a specific calculation processing function in the control device configured as described above will be described.
In general, the volumetric flow rate calculation equation of the throttle type flow meter, an intake air flow rate Qa (volumetric flow rate), the speed of sound a ₀ in the atmosphere, and the flow coefficient C, a opening area of the throttle 7 At the intake pressure Pe, large Using the atmospheric pressure Po and the specific heat ratio k, it is expressed by the following formula (1).

  Here, the dimensionless flow rate σ calculated by the dimensionless flow rate calculation means 18 is defined as the following formula (2).

  By substituting equation (2) into equation (1), the intake air flow rate can be written as in equation (3) below.

Note that the atmospheric sound velocity a ₀ is expressed by the following equation (4), where R is a gas constant and T ₀ is an intake air temperature.

Further, when the equation (3) is modified, the effective opening area CAt represented by the product of the flow coefficient C and the opening area At of the throttle 7 is a target intake air flow rate Qa * necessary for achieving the target torque, and When the sound velocity a ₀ in the atmosphere and the dimensionless flow rate σ are given, the calculation can be performed by the following equation (5).

Therefore, the target effective opening area calculation means 15 in the ECU 12 uses the equation (5) based on the target intake air flow rate Qa *, the sound velocity a ₀ in the atmosphere, and the dimensionless flow rate σ, and uses the target intake air flow rate Qa *. The target effective opening area CAt * for achieving the above can be calculated.

By the way, it is not practical to calculate the sound speed a ₀ in the atmosphere necessary for calculating the target effective opening area CAt * using the equation (4) in the ECU 12 because the calculation load becomes enormous.
In order to suppress the calculation load of in the ECU 12, the sound velocity calculation unit 20 is calculated in advance the theoretical values of the speed of sound a ₀ in the atmosphere, is stored as the map data for the intake air temperature To, the target effective opening area with intake air temperature to before calculation processing in the calculation unit 15 calculates the speed of sound a ₀ in the atmosphere.

Similarly, it is not practical to calculate the dimensionless flow rate σ necessary for calculating the target effective opening area CAt * using the equation (2) in the ECU 12 because the calculation load becomes enormous.
Therefore, in order to suppress the calculation load in the ECU 12, the dimensionless flow rate calculation means 18 calculates the theoretical value of the dimensionless flow rate σ in advance, and the pressure ratio between the intake pressure Pe and the atmospheric pressure Po as shown in FIG. FIG. 4 is obtained from the pressure ratio Pe / Po between the intake pressure Pe and the atmospheric pressure Po calculated by the pressure ratio calculation means 17 before the calculation processing by the target effective opening area calculation means 15. Using this, the dimensionless flow rate σ is calculated.

Incidentally, it is generally known that when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po is equal to or less than a predetermined value (about 0.528 in the case of air), the air flow rate through the throttle 7 is saturated (so-called choke). It is also known that when this choke occurs, the dimensionless flow rate σ calculated by the equation (2) becomes a constant value.
Therefore, when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po is equal to or less than a predetermined value, the pressure ratio calculation means 17 sets the pressure ratio between the intake pressure Pe and the atmospheric pressure Po to a predetermined value, so that even when choke occurs. Yes.
Instead of setting the pressure ratio between the intake pressure Pe and the atmospheric pressure Po to a predetermined value in the pressure ratio calculating means 17, the dimensionless flow rate calculating means 18 is a dimensionless represented by the pressure ratio between the intake pressure Pe and the atmospheric pressure Po. The map value of the flow rate σ may be the same as the predetermined value when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po is equal to or less than a predetermined value.

Further, since the AFS 4 is affected by the intake air pulsation when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po increases to some extent, an error may occur between the actual intake air flow rate and the measured intake air flow rate. . Further, the dimensionless flow rate σ may also be affected by the measurement error of the intake pressure Pe due to the intake air pulsation when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po increases to some extent. Therefore, when the pressure ratio between the intake pressure Pe and the atmospheric pressure Po is greater than or equal to a predetermined value, the pressure ratio calculating means 17 treats the pressure ratio between the intake pressure Pe and the atmospheric pressure Po as a predetermined value, thereby reducing the influence of intake air pulsation. As a result, the throttle controllability can be secured.
In the pressure ratio calculating means 17, instead of setting the pressure ratio between the intake pressure Pe and the atmospheric pressure Po to a predetermined value, the non-dimensional flow rate calculating means 18 is represented by the pressure ratio between the intake pressure Pe and the atmospheric pressure Po. The map value of the dimensional flow rate σ may be the same value as the case where the pressure ratio between the intake pressure Pe and the atmospheric pressure Po is equal to or greater than a predetermined value.

Further, the target opening calculation means 19 calculates the target opening TP * using the target effective opening area CAt * calculated by the target effective opening area calculation means 15. At this time, the target opening calculation means 19 Is obtained in advance a relationship between the measured value of the throttle opening TP and the effective opening area CAt calculated by the equation (5) from the measured value of the intake air amount Qa, and the throttle opening TP and the effective opening area CAt have a one-to-one relationship. Is stored as a corresponding two-dimensional map, and the target opening TP * corresponding to the target effective opening area CAt * is calculated by using this two-dimensional map.
Thereby, a two-dimensional map of the throttle opening TP and the effective opening area CAt can be easily created, and a significant reduction in setting man-hours can be realized.

By controlling the throttle 7 to the target throttle opening TP * calculated as described above, the actual intake air flow rate Qa detected from the AFS 4 changes. The estimated atmospheric pressure updating unit 16 calculates the estimated atmospheric pressure GPo so that the actual intake air flow rate Qa coincides with the target intake air flow rate Qa * calculated by the target intake air flow rate calculating unit 60, and outputs it as the atmospheric pressure Po. To do.
By controlling the throttle 7 with the output atmospheric pressure Po, the actual intake air flow rate Qa matches the target intake air flow rate Qa *, and the estimated atmospheric pressure GPo matches the atmospheric pressure Po.

  The target effective opening area calculating means 15, the target opening calculating means 19, the throttle 7, and the means (not shown) for controlling the driving of the throttle 7 are collectively referred to as a throttle opening control means 80. The throttle opening control means 80, the estimated atmospheric pressure update means 16, the intake air temperature sensor 5, the sonic speed calculation means 20, the pressure sensor 10, the pressure ratio calculation means 17, and the dimensionless flow rate calculation means 18 Are referred to as atmospheric pressure estimation means 70.

Next, a specific procedure of the atmospheric pressure estimation method in the atmospheric pressure estimation means 70, which is the main part of the present invention, will be described based on the flowchart shown in FIG.
First, in step S1, it is determined in the estimated atmospheric pressure update means 16 whether atmospheric pressure estimation is completed, and in the case of Yes, an atmospheric pressure estimation flow is complete | finished. In No, it progresses to Step S2.

In step S2, in the estimated atmospheric pressure update means 16, if the deviation of the target intake air flow rate Qa * is equal to or greater than the predetermined value A and the predetermined value A or greater is within the predetermined time, it is determined that the engine is undergoing a transient change. However, since the atmospheric pressure is likely to be erroneously estimated at the time of a transient change, the process proceeds to Yes and returns to the atmospheric pressure estimation start step S1. On the other hand, when the deviation of the target intake air flow rate Qa * is less than the predetermined value and exceeds the predetermined time, the result is No and the process proceeds to step S3.
Here, it is necessary to set the predetermined value A based on experiments. The deviation of the target intake air flow rate Qa * is obtained from the steady state in each operation state, and is set to a value that does not fall below this deviation. If the setting is lower, the estimated atmospheric pressure is not always executed. Conversely, if the deviation is set to be large with respect to the deviation, the estimated atmospheric pressure is executed even when the engine is in transient operation.

In step S3, the pressure ratio calculation means 17 calculates the pressure ratio (Pe) from the intake pressure Pe detected by the pressure sensor 10 and the atmospheric pressure Po for which the initial value of the estimated atmospheric pressure GPo is set by the estimated atmospheric pressure update means 16. / Po) is calculated.
In step S4, when the pressure ratio (Pe / Po) calculated by the pressure ratio calculation means 17 is equal to or less than the predetermined value B (about 0.528 in the case of air), the flow rate of air passing through the throttle is as described above. Since this is a region where saturation (so-called choke) occurs, the atmospheric pressure is likely to be erroneously estimated, so the process proceeds to Yes and returns to the atmospheric pressure estimation start step S1. On the other hand, when the pressure ratio (Pe / Po) is larger than the predetermined value B, the result is No and the process proceeds to step S5.

In step S5, when the pressure ratio (Pe / Po) calculated in step S3 is equal to or greater than the predetermined value C, as described above, it is affected by the intake air pulsation. Since an error may occur during the air flow rate, the atmospheric pressure may be erroneously estimated, so the process proceeds to Yes and returns to the atmospheric pressure estimation start step S1. On the other hand, if the pressure ratio (Pe / Po) is smaller than the predetermined value C, the result is No and the process proceeds to step S6.
In step S6, the dimensionless flow rate σ is calculated by the dimensionless flow rate calculation means 18 from the pressure ratio (Pe / Po) obtained in step S3, and the process proceeds to step S7.

In step S7, calculates the speed of sound a ₀ by sound velocity calculation unit 20 from the detected intake air temperature To at the intake air temperature sensor 5, the process proceeds to step S8.
In step S8, based on the dimensionless flow rate σ and sonic a ₀ calculated in step S6 and step S7, calculates the target effective opening area CAt * in the target effective opening area calculation unit 15, the throttle in the target opening calculating means 19 The target opening TP * is calculated and the throttle 7 is operated.

In step S9, the estimated atmospheric pressure update means 16 reads the actual intake air flow rate Qa detected from the AFS 4, performs averaging, calculates the average actual intake air flow rate Qave, and proceeds to step S10. About averaging, a moving average is performed for every predetermined period of a calculation period.
In step S10, it is determined whether the average intake air flow rate Qa has been averaged. If the averaging has been completed (Yes), the process proceeds to step S11. In the case of No, the process returns to the atmospheric pressure estimation start step S1.

  In step S11, the estimated atmospheric pressure update means 16 obtains a deviation ΔQa of the actual intake air flow rate Qa from the average actual intake air flow rate Qave averaged in step S9 according to the following equation (6). In this case, it is determined that the actual intake air flow rate Qa is not stable (during a transient change), and it is easy to erroneously estimate the atmospheric pressure, so the process proceeds to Yes and returns to the atmospheric pressure estimation start step S1.

ΔQa = | Average actual intake air flow rate Qave−Intake air flow rate Qa | (6)

If the deviation ΔQa of the actual intake air flow rate Qa is less than the predetermined value D, the result is No and the process proceeds to step S12.
Here, as with the above-described predetermined value A, the predetermined value D needs to be set based on experiments. The deviation of the actual intake air flow rate Qa is obtained from the steady state in each operating state, and the deviation is less than this deviation. Set to no value. If the setting is lower, the estimated atmospheric pressure is not always executed. Conversely, if the deviation is set to be large with respect to the deviation, the estimated atmospheric pressure is executed even when the engine is in transient operation.

In step S12, the estimated atmospheric pressure update unit 16 divides the target intake air flow rate Qa * by the average actual intake air flow rate Qave. If the divided value is equal to or less than a predetermined value E (for example, 1.05), the average actual intake flow rate is calculated. It is determined that the air flow rate Qave is larger than the target intake air flow rate Qa *, and the process proceeds to step S14.
If the value divided in step S12 is larger than the predetermined value E, the result is Yes and the process proceeds to step S13. In step S13, since the average actual intake air flow rate Qave is smaller than the target intake air flow rate Qa * in step S12, the atmospheric pressure is expressed by the following equation (1) so that the average actual intake air flow rate Qave matches the target intake air flow rate Qa *. Update according to 7).

GPo (n) = GPo (n−1) −predetermined value F (7)

  Here, the predetermined value F needs to be set based on experiments, and is set to a value that does not affect the driving state or does not give the driver an uncomfortable feeling by updating the estimated atmospheric pressure.

In step S14, the target intake air flow rate Qa * is divided by the average actual intake air flow rate Qave in the same manner as in step S12. If the divided value is equal to or greater than a predetermined value G (for example, 0.95), the result is Yes. It is determined that it matches Qa *, and the process proceeds to step S16.
If the value divided in step S14 is smaller than the predetermined value G (Yes), the process proceeds to step S15.
In step S15, since the average actual intake air flow rate Qave is larger than the target intake air flow rate Qa * in step S14, the atmospheric pressure is expressed by the following equation (1) so that the average actual intake air flow rate Qave matches the target intake air flow rate Qa *. Update according to 8).

GPo (n) = GPo (n−1) + predetermined value H (Equation 8)

Here, the predetermined value H needs to be set based on experiments, and is set to a value that does not affect the driving state or does not give the driver an uncomfortable feeling by updating the estimated atmospheric pressure.
In step S16, it is determined that the atmospheric pressure estimation in the atmospheric pressure estimating means 70 is completed, and the atmospheric pressure estimation flow is terminated. That is, the target throttle opening TP * is calculated in step S8 using the estimated atmospheric pressure data updated in steps S13 and S15, and the throttle 7 is controlled.

  Next, a specific change of each control value in the present invention will be described based on the time chart shown in FIG. FIG. 6 is a time chart in which atmospheric pressure estimation is performed in a state where the vehicle is moving from a highland down a slope to a lowland.

  At t1, the pressure ratio is within a predetermined range (predetermined value C ≦ pressure ratio (Pe / Po) ≦ predetermined value B), and a value obtained by dividing the target intake air flow rate Qa * by the average actual intake air flow rate Qave is a predetermined value G. By being less than, predetermined value H is added to presumed atmospheric pressure, and presumed atmospheric pressure is renewed. By updating the estimated atmospheric pressure, the target throttle opening degree operates, and the throttle opening degree operates on the closing side. By operating the throttle opening, the actual intake air flow rate Qa decreases, and the average actual intake air flow rate Qave also decreases.

When the difference ΔQa between the average actual intake air flow rate Qave and the actual intake air flow rate Qa becomes less than a predetermined value D at t2, it is determined that the actual intake air flow rate Qa is stable, and the target intake air flow rate Qa * is determined as the average actual intake air flow rate Qa *. The estimated atmospheric pressure is updated by the value divided by the flow rate Qave. Similarly, at t3, the estimated atmospheric pressure is updated.
At t4, when the value obtained by dividing the target intake air flow rate Qa * by the average actual intake air flow rate Qave is within a predetermined range (predetermined value G ≦ target intake air flow rate Qa * / average actual intake air flow rate Qave ≦ predetermined value E), The target intake air flow rate Qa * and the actual intake air flow rate Qa match, and the estimated atmospheric pressure matches the actual atmospheric pressure.

As described above, according to the present invention, the estimated atmospheric pressure, the target intake air flow rate, the intake pressure and the intake air temperature are applied to the flow rate calculation formula of the throttle type flow meter, and the throttle opening control means The target effective opening area is calculated from the target effective opening area using a target effective opening area calculating means for calculating the target effective opening area and a correspondence map between the effective opening area and the throttle opening of the throttle opening control means adapted in advance. Includes correction due to detection delay of the airflow sensor by providing target opening calculation means for calculating and estimated atmospheric pressure updating means for updating the estimated atmospheric pressure so that the actual intake air flow rate matches the target intake air flow rate First, the atmospheric pressure can be estimated so that the actual intake air flow rate matches the target intake air flow rate, and the atmospheric pressure can be estimated early and accurately.

Further, the amount of change in the target intake air flow rate calculated by the target intake air flow rate calculation means is calculated, and when the calculated change amount is equal to or greater than a predetermined value and the state equal to or greater than the predetermined value is within a predetermined time, atmospheric pressure By stopping the update of the estimation, it is possible to suppress an erroneous estimation of the atmospheric pressure due to a large variation in the target intake air flow rate when the change amount of the target intake air flow rate is equal to or greater than a predetermined value.
Further, the amount of change in the actual intake air flow rate detected by the actual intake air flow rate detection means is calculated, and when the calculated change amount is greater than or equal to a predetermined value, the update of the estimated atmospheric pressure is stopped to stop the actual target intake air flow. It is possible to suppress an erroneous estimation of the atmospheric pressure due to a large variation in the air flow rate.

  Furthermore, a pressure ratio calculating means for obtaining a pressure ratio from the intake pressure and the estimated atmospheric pressure is provided, and when the calculated pressure ratio is outside the predetermined range, the air passing through the throttle is stopped by stopping the update of the estimated atmospheric pressure. Suppresses erroneous estimation of atmospheric pressure due to an area where an error occurs between the actual intake air flow rate and the measured intake air flow rate due to the influence of the intake air pulsation and the region where the flow rate of air is saturated (so-called choke) Can do.

  In addition, in embodiment mentioned above, it can apply, also when using the intake air flow rate estimated from another sensor other than the actual intake air flow rate detected with the airflow sensor as an actual intake air flow rate. Moreover, although the case where this invention was applied to the engine control apparatus which employ | adopted the torque base control system was demonstrated, it is applicable also in engine control systems other than torque base control.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

1: engine body, 2: intake pipe, 3: exhaust pipe,
4: air flow sensor (AFS), 5: intake air temperature sensor, 6: accelerator opening sensor,
7: throttle, 8: throttle opening sensor,
9: Surge tank, 10: Pressure sensor, 11: Rotational speed sensor,
12: Electronic control unit (ECU), 13: Injector, 14: Ignition coil,
15: target effective opening area calculating means, 16: estimated atmospheric pressure updating means,
17: Pressure ratio calculating means, 18: Dimensionless flow rate calculating means, 19: Target opening degree calculating means,
20: Sound velocity calculation means, 30: Various sensors, 40: Various actuators,
50: Driver request torque calculation means 51: Loss torque calculation means,
52: ISC torque calculation means 53: Filling efficiency conversion means,
60: target intake air flow rate calculating means, 70: atmospheric pressure estimating means,
80: Throttle opening control means

Claims (4)

In a control apparatus for an internal combustion engine comprising atmospheric pressure estimation means for estimating an atmospheric pressure to be applied to calculation of a control parameter of the internal combustion engine,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Target intake air flow rate calculating means for calculating a target intake air flow rate based on the operating state of the internal combustion engine;
A throttle provided in an intake passage of the internal combustion engine;
Throttle opening control means for changing the effective opening area of the intake passage by controlling the throttle opening of the throttle, and variably controlling the intake amount to the internal combustion engine;
An actual intake air flow rate detecting means for detecting an actual intake air flow rate to the internal combustion engine;
Intake pressure detection means for detecting the pressure on the internal combustion engine side of the throttle as intake pressure;
An intake air temperature detecting means for detecting an intake air temperature on the atmosphere side of the throttle,
The atmospheric pressure estimating means includes
Applying the estimated atmospheric pressure, the target intake air flow rate, the intake pressure and the intake air temperature to the flow rate calculation formula of the throttle type flow meter to calculate the target effective opening area of the throttle opening control means Opening area calculating means;
A target opening calculation means for calculating a target throttle opening from the target effective opening area, using a correspondence map between the effective opening area of the throttle opening control means and the throttle opening adapted in advance;
Estimated atmospheric pressure update means for updating the estimated atmospheric pressure so that the actual intake air flow rate matches the target intake air flow rate,
The target opening calculation means calculates the target throttle opening using the estimated atmospheric pressure updated by the estimated atmospheric pressure update means, and controls the throttle opening to the target throttle opening. Control device for an internal combustion engine. The atmospheric pressure estimating means includes
In the estimated atmospheric pressure update means, a change amount of the target intake air flow rate calculated by the target intake air flow rate calculation means is calculated, and the calculated change amount is not less than a predetermined value and the state not less than the predetermined value is within a predetermined time. In this case, the update of the estimated atmospheric pressure is stopped, and the control device for an internal combustion engine according to claim 1, wherein the update of the estimated atmospheric pressure is stopped. The atmospheric pressure estimating means includes
The estimated atmospheric pressure update means calculates the change amount of the actual intake air flow rate detected by the actual intake air flow rate detection means, and stops updating the estimated atmospheric pressure when the calculated change amount is a predetermined value or more. The control apparatus for an internal combustion engine according to claim 1 or 2, wherein The atmospheric pressure estimating means includes
Pressure ratio calculating means for obtaining a pressure ratio from the intake pressure and the estimated atmospheric pressure;
The control of the internal combustion engine according to any one of claims 1 to 3, wherein updating of the estimated atmospheric pressure is stopped when the pressure ratio calculated by the pressure ratio calculating means is outside a predetermined range. apparatus.

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