JP2002180877A - Controller of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller of an internal combustion engine capable of correctly and easily calculating an amount of the air taken into the internal combustion engine. SOLUTION: In this controller of the internal combustion engine for calculating the amount of the intake air taken into the engine having a variable valve timing mechanism, whether the intake pressure Pm of an intake pipe connected to the internal combustion engine, is less than a predetermined intake pressure Pc or not is determined (S12), the amount of the intake air Mc is calculated on the basis of a first relational expression as a linear expression of the intake pressure of the intake pipe when the intake pressure Pm of the intake pipe is below a predetermined intake pressure Pc (S14), and the amount of the intake air Mc is calculated (S16) on the basis of a second relational expression which is the linear expression of the intake pressure of the intake pipe, and ahs an inclination different from the first relational expression, when the intake pressure Pm of the intake pipe is not below the predetermined intake pressure Pc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine control device for calculating an amount of air taken into an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine of a vehicle, in order to realize good air-fuel ratio control, it is necessary to grasp an accurate intake air amount supplied into a cylinder. Conventionally, as a calculation for calculating an intake air amount of air taken into an internal combustion engine, as described in JP-A-8-334050, an intake pipe pressure time differential value is calculated as a function of an intake pipe pressure as an intake pipe pressure. By transforming the state equation at to a differential equation and approximating the function to a linear function and performing the annealing process,
It is known that an intake pipe pressure is calculated for each elapsed time after a change in the throttle valve opening and the engine speed, and the calculated intake pipe pressure is obtained as an intake valve passing air amount based on a linear expression (see the related art). FIG. 3 (B) of the publication.

[0003]

In the above-described apparatus, since the intake pipe pressure and the intake air amount are approximated by a linear expression over the entire range of the intake pipe pressure, the memory load and the arithmetic load of the arithmetic unit can be reduced. .

However, since the correspondence between the actual intake pipe pressure and the actual intake air amount is different from the linear expression, there is a problem that a certain amount of error is included in the entire region. In particular, in an internal combustion engine equipped with a variable valve mechanism, the calculation error of the intake air amount becomes large when the intake valve and the exhaust valve overlap at the same time in the open state.

In order to accurately calculate the intake air amount, a map processing using a map relating to the intake pipe pressure and the intake air amount may be considered. However, in this case, the data amount increases, a large ROM capacity is required, and the calculation load also increases.

The present invention has been made in order to solve such a problem, and it is an object of the present invention to provide an internal combustion engine control device capable of accurately and easily calculating the amount of air taken into the internal combustion engine. Aim.

[0007]

That is, an internal combustion engine control device according to the present invention is an internal combustion engine control device for calculating the amount of intake air to be taken into the internal combustion engine. Is a primary expression of the intake pressure of the intake pipe when the determination means determines whether the intake pressure is equal to or lower than a predetermined intake pressure and the determination means determines that the intake pressure of the intake pipe is equal to or lower than the predetermined intake pressure. An intake air amount is calculated based on the first relational expression. When the determination means determines that the intake pressure of the intake pipe is not lower than a predetermined intake pressure, it is a linear expression of the intake pressure of the intake pipe, the first relational expression Calculating means for calculating the intake air amount based on a second relational expression having a slope different from the above.

According to the present invention, the relationship between the intake air amount and the intake pressure of the intake pipe is approximated to the actual state by calculating the intake air amount based on at least two relational expressions according to the intake pressure of the intake pipe. Thus, the intake air amount can be accurately calculated. Further, since the intake air amount is calculated based on the relational expression, the calculation of the intake air amount is simpler than the case where the relationship between the intake pressure and the intake air amount is mapped and processed.

Further, in the internal combustion engine control device according to the present invention, the first relational expression and the second relational expression are set so as to pass through the same point at a predetermined intake pressure in a coordinate system of the intake pressure and the intake air amount. It is characterized by being.

According to the present invention, since the first relational expression and the second relational expression are set so as to pass through the same point, the first relational expression and the second relational expression are set in the coordinate system of the intake pressure and the intake air amount. The straight line according to the equation is always continuous. For this reason, even if the setting of the coefficient specifying the first relational expression and the second relational expression is changed, the continuity of the straight lines related to the first relational expression and the second relational expression is maintained, and the internal combustion engine can be appropriately controlled. . In addition, it is possible to calculate the intake pressure back based on the intake air amount using the inverse function of the first relational expression and the second relational expression.

Further, since the first relational expression and the second relational expression may be set as expressions having a predetermined slope and passing through a predetermined same point, the amount of setting data may be small, and the memory capacity and the calculation load may be reduced. I can do it.

The internal combustion engine control device according to the present invention calculates an intake air amount to be taken into the internal combustion engine, wherein the intake pressure of an intake pipe connected to the internal combustion engine is lower than a predetermined intake pressure. Determining means for determining whether or not there is;
When the determining means determines that the intake pressure of the intake pipe is lower than a predetermined intake pressure, the intake air amount is calculated based on a linear expression of the intake pressure of the intake pipe, and the determining means determines that the intake pressure of the intake pipe is predetermined. And calculating means for calculating the intake air amount based on a quadratic or higher expression of the intake pressure of the intake pipe when it is determined that the intake air pressure is not lower than the intake pressure.

According to the present invention, it is possible to more accurately calculate the intake air amount.

According to another aspect of the present invention, there is provided an internal combustion engine control device for calculating an intake pressure of an intake pipe connected to the internal combustion engine, wherein an intake air amount taken into the internal combustion engine is equal to or less than a predetermined intake air amount. Determining means for determining whether or not the primary intake air amount to be taken into the internal combustion engine when the determining means determines that the intake air amount to be taken into the internal combustion engine is equal to or less than a predetermined intake air amount An intake pressure is calculated based on a first relational expression, which is an expression, and when the determination means determines that the amount of intake air to be taken into the internal combustion engine is not less than or equal to a predetermined intake air amount, the intake air taken into the internal combustion engine Calculating means for calculating the intake pressure based on a second relational expression that is a linear expression of the amount and has a different slope from the first relational expression.

In the internal combustion engine control apparatus according to the present invention, the first relational expression and the second relational expression are set so as to pass through the same point at a predetermined intake air amount in a coordinate system of the intake pressure and the intake air amount. It is characterized by being.

According to these inventions, the relationship between the intake air amount and the intake pressure of the intake pipe is approximated to the actual state by calculating the intake pressure based on at least two relational expressions according to the intake air amount. Thus, the intake pressure can be accurately calculated. Further, since the intake pressure is calculated based on the relational expression, the calculation of the intake pressure becomes simpler than the case where the relationship between the intake pressure and the intake air amount is mapped and processed.

By setting the first relational expression and the second relational expression so as to pass through the same point, a straight line relating to the first relational expression and the second relational expression in the coordinate system of the intake pressure and the intake air amount is obtained. It is always continuous. For this reason, even if the setting of the coefficient specifying the first relational expression and the second relational expression is changed, the continuity of the straight lines related to the first relational expression and the second relational expression is maintained, and the internal combustion engine can be appropriately controlled. . In addition, it is also possible to perform an inverse calculation of the intake air amount based on the intake pressure using an inverse function expression of the first relational expression and the second relational expression.

Further, since the first relational expression and the second relational expression may be set as an expression having a predetermined slope and passing through a predetermined same point, the amount of setting data may be small, and the memory capacity and the calculation load may be reduced. I can do it.

The internal combustion engine control device according to the present invention is characterized in that the internal combustion engine has a variable valve mechanism.

According to the present invention, the predetermined intake pressure is set in accordance with the valve operating characteristics of the variable valve operating mechanism, and suction is performed based on different relational expressions in the high pressure side and the low pressure side of the set intake pressure. By calculating the air amount, the intake air amount can be accurately calculated according to the valve operating characteristics of the variable valve mechanism. In addition, a predetermined intake air amount is set according to the valve operating characteristics of the variable valve operating mechanism, and the intake pressure is calculated based on a different relational expression in each of the regions on the side larger than and smaller than the set intake air amount. Thus, the intake pressure can be accurately calculated according to the valve operating characteristics of the variable valve operating mechanism.

[0021]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. (First Embodiment) FIG. 1 is an explanatory diagram of an internal combustion engine control device according to the present embodiment.

As shown in the figure, the internal combustion engine control device comprises:
This is a device for calculating the amount of intake air taken into a cylinder of the engine 2 which is an internal combustion engine. The engine 2 for which the intake air amount is calculated has a variable valve mechanism. For example, the engine 2 includes a variable valve timing mechanism 5 that changes the opening / closing timing of the intake valve 3 and the exhaust valve 4 as a variable valve mechanism. The variable valve timing mechanism 5 is electrically connected to the ECU 6,
It operates based on a control signal output from the ECU and outputs a detection signal relating to valve timing to the ECU 6 via a detection sensor 7 such as a cam position sensor.

The engine 2 is provided with a crank position sensor 12. Crank position sensor 1
Reference numeral 2 denotes a sensor for detecting the engine speed.
6 and outputs a detection signal to the ECU 6.

The engine 2 is provided with an injector 9 for injecting fuel into the combustion chamber 8. Injector 9
Is a fuel injection means for supplying fuel to the combustion chamber 8, and is provided for each cylinder 10 provided in the engine 2.
The combustion chamber 8 has a piston 11 disposed in a cylinder 10.
Is formed above. An intake valve 3 and an exhaust valve 4 are provided above the combustion chamber 8.

An intake manifold 20 is connected upstream of the intake valve 3. Intake manifold 20
A surge tank 21 is connected to the upstream side of the tank. Intake manifold 20 and surge tank 21 constitute an intake pipe connected to engine 2. Further, an air cleaner 22 is provided in an intake passage on the upstream side of the surge tank 21.

At a position upstream of the surge tank 21, a throttle valve 23 is provided. Throttle valve 2
3 operates based on a control signal of the ECU 6. The throttle opening of the throttle valve 23 is detected by a throttle position sensor 24 and input to the ECU 6.

An air flow meter 25 is provided downstream of the air cleaner 22. Air flow meter 2
Reference numeral 5 denotes intake air amount detection means for detecting an intake air amount. The detection signal of the air flow meter 25 is input to the ECU 6.

The ECU 6 controls the entire internal combustion engine control device 10, and includes a CPU, a ROM, and a RAM.
It is mainly composed of a computer including RO
M stores various control routines including an intake air amount calculation routine.

Next, the operation of the internal combustion engine control device according to this embodiment will be described.

FIG. 2 is a flowchart showing the operation of the internal combustion engine control device.

Step S10 (hereinafter simply referred to as "S1
0 ". The same applies to other steps. In), the calculation of the intake pressure Pm of the intake pipe is performed. The intake pressure Pm of the intake pipe is determined by the throttle valve 23 in the intake pipe.
This is the pressure of the intake pipe on the downstream side.
5 is calculated based on the intake air amount detected.

The intake pressure Pm of the intake pipe may be calculated based on the throttle opening of the throttle valve 23. Further, a pressure sensor for directly detecting the intake pressure is provided in the intake pipe, and the detection signal of the pressure sensor is read to obtain the intake pressure P.
m may be used.

Then, the flow shifts to S12, where it is determined whether the intake pressure Pm of the intake pipe is equal to or lower than a predetermined intake pressure Pc set in the ECU 6 in advance. The intake pressure Pc is set based on the valve operating characteristics of the variable valve timing mechanism 5 and in accordance with the engine speed detected by the crank position sensor 12, the valve timing detected by the detection sensor 7, and the like. For example, the intake pressure Pc is set low based on the valve operating characteristics of the variable valve timing mechanism 5 when the engine speed is high, and is set high when the engine speed is low.

In S12, when it is determined that the intake pressure Pm of the intake pipe is equal to or less than the set intake pressure Pc,
The process proceeds to S14, where the intake air amount Mc is calculated based on the following first relational expression (1) which is a linear expression of the intake pressure Pm of the intake pipe.

Mc = al · Pm−bl ‥‥ (1) On the other hand, if it is determined in S12 that the intake pressure Pm of the intake pipe is not lower than the set intake pressure Pc, the program proceeds to S16.
The intake air amount Mc is calculated based on the following second relational expression (2), which is a linear expression of the intake pressure Pm of the intake pipe and has a different slope from the first relational expression.

Mc = ah · Pm−bh ‥‥ (2) FIG. 3 shows the relationship between the intake pressure Pm and the intake air amount Mc in the calculation of the intake air amount Mc in S14 and S16.

As shown by the solid line in FIG. 3, when the intake pressure Pm in the intake pipe is equal to or less than the set intake pressure Pc, the intake amount Mc is calculated based on the first relational expression (Mc = alPm-bl). When the intake pressure Pm of the intake pipe is larger than the set intake pressure Pc, the intake air amount Mc is calculated based on the second relational expression (Mc = ah · Pm−bh).

At this time, the slope al of the first relational expression and the slope ah of the second relational expression are set to different values.
The slope al of the first relational expression is set smaller than the slope ah of the second relational expression. As a result, as shown by the broken line in FIG. 3, it is possible to calculate an intake air amount closer to the actual intake air amount, as compared with a case where the intake air amount is calculated using only one linear equation for the entire region of the intake air pressure.

Further, the slope al, intercept bl,
The slope ah and the intercept bh of the second relational expression are parameters depending on the valve timing of the variable valve timing mechanism 5 and the engine speed. The slope al of the first relational expression and the slope ah of the second relational expression are set to different values according to the state of the valve timing of the variable valve timing mechanism 5, for example, when the intake valve 3 and the exhaust valve 4 are simultaneously opened. As (valve overlap) becomes longer, the slope al of the first relational expression is set smaller, and the slope ah of the second relational expression is set larger. This makes it possible to calculate an intake air amount close to the actual intake air amount.

When the variable valve timing mechanism 5 can change the phase and the lift amount, the gradient al, the intercept bl, and the intercept bl of the first relational expression are changed according to the phase and the lift amount.
The slope ah and the intercept bh of the second relational expression are set.

In FIG. 3, when the intake valve 3 and the exhaust valve 4 are not simultaneously opened when the engine 2 is driven (when there is no valve overlap), as shown by the broken line, the intake air amount Mc Can be calculated over the entire region of the intake pressure of the intake pipe by one straight line, that is, by one linear expression.

That is, when calculating the amount of air in the cylinder of the engine 2 using the equation of state PV = MRT, the cylinder pressure P at the moment when the intake valve 3 is closed is substantially equal to the intake pipe pressure. If the intake pipe pressure is substituted for the pressure P and the cylinder volume when the intake valve 3 is closed is set to V, the air amount M in the cylinder can be calculated. At that time, although the burned gas component is also contained in the cylinder, the burned gas amount can be considered to be substantially constant when the closing timing of the exhaust valve 4 is fixed. Therefore, the amount of intake air in the cylinder (new air) mc
Can be approximated by a straight line as a linear expression of the intake pressure Pm by the following expression (3).

Mc = A · Pm−B ‥‥ (3) At this time, A is set based on V / (RT),
B is set based on the burned gas amount. Note that R is a gas constant and T is a temperature.

However, when there is a valve overlap, a backflow from the exhaust side to the intake side of the cylinder occurs, so that the amount of burned gas remaining in the cylinder with respect to the intake pipe pressure according to the state of the valve overlap. Will be different. Therefore, an approximate expression such as Expression (3) cannot accurately calculate the intake air amount.

The reverse flow from the cylinder to the intake pipe when the intake valve 3 is opened is determined by the difference between the cylinder pressure and the intake pipe pressure.

FIG. 4 shows the relationship between the pressure ratio upstream and downstream of the intake valve 4 and the reverse flow rate. As shown in the figure, when the upstream / downstream pressure ratio of the valve (upstream intake pipe pressure / downstream cylinder pressure) decreases, the reverse flow rate also increases. For this reason, a change occurs in the intake air amount according to the change in the intake pipe pressure.

When the pressure ratio upstream and downstream of the valve is smaller than a certain pressure ratio, the reverse flow becomes substantially constant, and the relationship between the pressure ratio upstream and downstream of the valve and the reverse flow changes. It is considered that this is because even if the pressure ratio changes, the volume in the cylinder is smaller than that of the intake pipe and the pressure changes faster, so that the integration amount of the air passing through the intake valve 3 hardly changes. Therefore, since the intake air amount changes depending on whether or not the intake pipe pressure is equal to or lower than a certain pressure, a different calculation formula is required depending on whether or not the intake pipe pressure is equal to or less than a certain pressure in order to accurately calculate the intake air amount. Need to be used.

When there is valve overlap, the cylinder volume changes according to the valve timing. As a result, the intake air amount changes, and therefore, the expression (3)
With such an approximate expression, the intake air amount cannot be calculated accurately. In this case, by appropriately setting the parameters al, bl, ah, and bh in the above equations (1) and (2) according to the engine speed and the valve timing, it is possible to accurately calculate the intake air amount.

As described above, according to the internal combustion engine control apparatus according to the present embodiment, the intake air amount Mc is changed to the intake pressure P of the intake pipe.
By calculating based on two relational expressions (1) and (2) according to m, the relationship between the intake air amount and the intake pressure of the intake pipe can be approximated to an actual state, and the intake air amount can be accurately calculated. Can be calculated. In particular, a predetermined intake pressure Pc is set in accordance with the valve operating characteristics of the variable valve timing mechanism 5, and the intake air amount is calculated based on different relational expressions in the high pressure side and the low pressure side of the set intake pressure Pc. By doing so, it is possible to accurately calculate the intake air amount according to the valve operating characteristics of the variable valve operating mechanism.

Further, since the intake air amount is calculated based on the relational expression, the calculation of the intake air amount becomes simpler than the case of a map process or the like. For example, in the internal combustion engine control device according to the present embodiment, the parameters al and bl of the first relational expression, the parameters ah and bh of the second relational expression, and the set intake pressure Pc can be set at a certain engine speed and valve timing. For example, the intake air amount can be calculated. For this reason, the amount of data to be stored can be significantly reduced as compared with the map processing using the map relating to the intake pipe pressure and the intake air amount. Further, since the calculation formula for calculating the intake air amount is a linear formula, the calculation becomes easy, and the calculation load can be reduced.

In particular, the present invention is very useful when applied to an engine for controlling a torque demand type engine. (Second Embodiment) Next, an internal combustion engine control device according to a second embodiment will be described.

The internal combustion engine control device according to the present embodiment has substantially the same configuration as the internal combustion engine control device according to the first embodiment, but has a first relational expression for calculating the intake air amount,
The difference is that a relational expression other than the above expressions (1) and (2) is used as the second relational expression.

FIG. 5 is a flowchart showing the operation of the internal combustion engine control device according to the present embodiment. The internal combustion engine control device according to the present embodiment has the same hardware configuration as the internal combustion engine control device according to the first embodiment shown in FIG.

As shown in S20 of FIG. 5, the calculation of the intake pressure Pm of the intake pipe is performed. The calculation of the intake pressure Pm is performed in the same manner as in S10 of FIG. 2, and is performed based on, for example, the amount of intake air detected by the air flow meter 25.
Further, the intake pressure Pm of the intake pipe may be calculated based on the throttle opening of the throttle valve 23. Further, a pressure sensor for directly detecting the intake pressure may be provided in the intake pipe, and a detection signal of the pressure sensor may be read and used as the intake pressure Pm.

Then, the flow shifts to S22, where it is determined whether the intake pressure Pm of the intake pipe is equal to or lower than a predetermined intake pressure Pc set in the ECU 6 in advance. The intake pressure Pc is set based on the valve operating characteristics of the variable valve timing mechanism 5 and in accordance with the engine speed detected by the crank position sensor 12, the valve timing detected by the detection sensor 7, and the like. For example, the intake pressure Pc is set low based on the valve operating characteristics of the variable valve timing mechanism 5 when the engine speed is high, and is set high when the engine speed is low.

In S22, when it is determined that the intake pressure Pm of the intake pipe is equal to or lower than the set intake pressure Pc,
The process proceeds to S24, and the intake air amount Mc is calculated based on the following first relational expression (4), which is a linear expression of the intake pressure Pm of the intake pipe.

Mc = al · (Pm−Pc) + Qc (4) On the other hand, when it is determined in S22 that the intake pressure Pm of the intake pipe is not lower than the set intake pressure Pc, the process proceeds to S26.
The intake air amount Mc is calculated based on the following second relational expression (5), which is a linear expression of the intake pressure Pm of the intake pipe and has a different slope from the first relational expression.

Mc = ah · (Pm−Pc) + Qc (5) Here, FIG. 6 shows the relationship between the intake pressure Pm and the intake air amount Mc in the calculation of the intake air amount Mc in S24 and S26.

As shown in FIG. 6, when the intake pressure Pm in the intake pipe is equal to or lower than the set intake pressure Pc, the first relational expression (Mc = al
The intake air amount Mc is calculated based on (Pm−Pc) + Qc). If the intake pressure Pm of the intake pipe is larger than the set intake pressure Pc, the second relational expression (Mc = ah · (Pm−Pc) + Q)
The intake air amount Mc is calculated based on c).

The first relational expression and the second relational expression are set so as to pass through the same point at the intake pressure Pc in the coordinate system of the intake pressure Pm and the intake air amount Mc. For example, in the coordinate system of the intake pressure Pm and the intake air amount Mc, the first relational expression and the second relational expression are set such that the straight lines related to the first relational expression and the second relational expression pass through the same point (Pc, Qc). An expression has been set.

The coefficient P in the first and second relational expressions
The same value is used for c and Qc. On the other hand, the slope coefficients al and ah in the first relational expression and the second relational expression are set to different values, for example, the inclination al of the first relational expression is set to be smaller than the inclination ah of the second relational expression.

As described above, according to the internal combustion engine control of this embodiment, the same point (Pc, Q
By setting the first relational expression and the second relational expression so as to pass through c), straight lines related to the first relational expression and the second relational expression are always continuous in the coordinate system of the intake pressure Pm and the intake air amount Mc. Become. For this reason, the coefficients al, ah,
Even if the settings of Pc and Qc are changed, the continuity of the straight lines according to the first relational expression and the second relational expression is maintained. Therefore, an appropriate intake air amount can be calculated, and appropriate engine control can be performed.

For example, al is 0.9, ah is 2.1, P
When c is set to 49.5 and Qc is set to 50.4, the first relational expression and the second relational expression are set, the first relational expression is expressed as the following expression (6), and the second relational expression is It is expressed as (7).

Mc = 0.9 · (Pm−49.5) +50.4 (Pm ≦ 49.5) (6) Mc = 2.1 · (Pm−49.5) +50.4 (Pm> 49) .5)... (7) The straight lines according to the first relational expression of the expression (6) and the second relational expression of the expression (7) are continuous as shown by the solid line in FIG.

Here, the coefficients al (0.9), ah in the first relational expression of Expression (6) and the second relational expression of Expression (7)
When the settings of (2.1), Pc (49.5), and Qc (50.4) are changed by rounding off the decimal places, the first relational expression of Expression (6) becomes the following Expression (8). The second relational expression of the expression (7) is the following expression (9).

Mc = 1 · (Pm−50) +50 (Pm ≦ 50) (8) Mc = 2 · (Pm−50) +50 (Pm> 50) (9) First relation of this equation (8) The straight line according to the expression and the second relational expression of the expression (9) is continuous as shown by the broken line in FIG. 7, and the continuity of the two straight lines is maintained.
Therefore, an appropriate intake air amount can be calculated, and engine control can be performed with a good air-fuel ratio.

On the other hand, when the equations (6) and (7) are modified to set the first relational expression and the second relational expression as coefficients of only the slope and the intercept, the first relational expression and the second relational expression become Equation (1)
0) and (11).

Mc = 0.9 · Pm + 5.85 (Pm ≦ 49.5) (10) Mc = 2.1 · Pm−53.55 (Pm> 49.5) (11) Slope coefficient and intercept coefficient Equations (10) and (11) are obtained by rounding off the decimal places of
3).

Mc = 1 · Pm + 6 (Pm ≦ 50) (12) Mc = 2 · Pm−54 (Pm> 50) (13) Then, the first relational expression of Expression (12) and Expression (13) The straight line according to the second relational expression is discontinuous at the boundary where the intake air amount is Pm = 50, as shown by the one-dot chain line in FIG. In this case, when the intake air amount changes discontinuously, not only may the air-fuel ratio deteriorate, but also drivability may deteriorate. For this reason, it is necessary to change each coefficient in consideration of the entire coefficient, which makes maintenance and the like complicated.

Further, according to the internal combustion engine control according to the present embodiment, the intake pressure can be back calculated based on the intake air amount using the inverse function of the first relational expression and the second relational expression.
That is, by relating the intake pressure Pm and the intake air amount Mc by the first relational expression and the second relational expression, the intake pressure Pm and the intake air amount Mc have a one-to-one continuous relationship. The intake pressure can be calculated back.

Further, since the first relational expression and the second relational expression may be set as expressions having a predetermined slope and passing through a predetermined same point, only a small amount of setting data is required, and the memory capacity and the calculation load can be reduced. I can do it. For example, in the internal combustion engine control device according to the present embodiment, four coefficient data of Pc, Qc, al, and ah may be set as a map for each engine speed and valve timing, and the number of data is reduced. Thus, the memory capacity and the calculation load can be reduced. (Third Embodiment) Next, an internal combustion engine control device according to a third embodiment will be described.

The internal combustion engine control device according to the present embodiment is a device for calculating the intake pressure of the intake pipe of the engine 2. The internal combustion engine control device according to the present embodiment has the same hardware configuration as the internal combustion engine control device according to the first embodiment shown in FIG.

FIG. 8 is a flowchart showing the operation of the internal combustion engine control device according to the present embodiment.

As shown in S30 of FIG. 8, the calculation of the intake air amount Mc sucked into the engine 2 is performed. The calculation of the intake air amount Mc is performed, for example, by setting a target intake air amount based on the accelerator opening. Further, the calculation may be performed based on the fuel injection amount and the air-fuel ratio.

Then, the flow shifts to S32, where it is determined whether the intake air amount Mc taken into the engine 2 is equal to or less than a predetermined intake air amount Qc set in the ECU 6 in advance. The intake air amount Qc is set based on the valve operating characteristics of the variable valve timing mechanism 5 according to the engine speed detected by the crank position sensor 12, the valve timing detected by the detection sensor 7, and the like.

In S32, when it is determined that the intake air amount Mc is equal to or less than the set intake air amount Qc,
The process proceeds to S34, and the intake pressure Pm is calculated based on the following first relational expression (14), which is a linear expression of the intake air amount Mc.

Pm = (Mc−Qc) / al + Pc (14) On the other hand, in S32, the intake air amount Mc is changed to the intake air amount Q.
When it is determined that it is not equal to or less than c, the process proceeds to S36,
Based on the following second relational expression (15), which is a linear expression of the intake air amount Mc and has a different slope from the first relational expression, the intake pressure P
m is calculated.

Pm = (Mc−Qc) / ah + Pc (15) As described above, according to the internal combustion engine control according to the present embodiment, the first relationship is established such that the predetermined intake air amount Qc passes through the same point. Since the equation and the second relational expression are set, the straight lines related to the first relational expression and the second relational expression are always continuous in the coordinate system of the intake pressure Pm and the intake air amount Mc. Therefore, even if the coefficients al, ah, Pc, and Qc of the first relational expression and the second relational expression are changed, the continuity of the straight lines related to the first relational expression and the second relational expression is maintained. Therefore, an appropriate intake pressure Pm can be calculated, and an appropriate engine control can be performed.

Further, since the first relational expression and the second relational expression may be set as an expression having a predetermined slope and passing through a predetermined same point, the set data may be small, and the memory capacity and the calculation load may be reduced. I can do it. For example, in the internal combustion engine control device according to the present embodiment, four coefficient data of Pc, Qc, al, and ah may be set as a map for each engine speed and valve timing, and the number of data is reduced. Thus, the memory capacity and the calculation load can be reduced. (Fourth Embodiment) Next, an internal combustion engine control device according to a fourth embodiment will be described.

In the internal combustion engine control devices according to the first embodiment and the second embodiment, the case where the intake air amount is calculated by using two linear expressions has been described. It is not limited to things.

The internal combustion engine control apparatus according to the present embodiment sets two or more intake pressures in the entire range of the intake pipe pressure, and sets three or more distinct linear equations between the set intake pressures. Is used to calculate the intake air amount.

According to such an internal combustion engine control device, the intake air amount can be calculated more accurately than the internal combustion engine control device according to the first embodiment. (Fifth Embodiment) Next, an internal combustion engine control device according to a fifth embodiment will be described.

In the internal combustion engine control device according to the third embodiment, the case where the intake pressure is calculated using two linear expressions has been described. However, the internal combustion engine control device according to the present invention is not limited to such a case. Absent.

The internal combustion engine control device according to the present embodiment sets two or more intake air amounts over the entire intake air amount range,
The intake pressure is calculated using three or more separate linear expressions in the region between the set intake air amounts.

According to such an internal combustion engine control device, the intake pressure can be calculated more accurately than the internal combustion engine control device according to the third embodiment. (Sixth Embodiment) Next, an internal combustion engine control device according to a sixth embodiment will be described.

In the internal combustion engine control devices according to the first to fifth embodiments, the case where the intake air amount or the intake pressure is calculated using a primary expression has been described. It is not limited to such.

The internal combustion engine control device according to the present embodiment calculates the intake air amount or intake pressure using curves such as a primary equation and a secondary equation. For example, when a constant intake pressure Pc is set, and it is determined that the intake pressure Pm of the intake pipe is equal to or less than the set intake pressure Pc, the intake air amount Mc is determined based on the above-described first relational expression (1). calculate. On the other hand, when it is determined that the intake pressure Pm of the intake pipe is not lower than the set intake pressure Pc, the intake air amount Mc is calculated based on the following quadratic equation (16).

Mc = a · (Pm) ² + b · Pm + c (16) In the region higher than the intake pressure Pc, the curve is approximated not by the quadratic expression of the intake pressure Pm of the intake pipe but by another curve. You may.

According to such an internal combustion engine control device, it is possible to calculate the intake air amount more accurately than the internal combustion engine control devices according to the first to fifth embodiments.

[0090]

As described above, according to the present invention, the intake air amount or the intake pressure is calculated based on at least two relational expressions in accordance with the intake pressure or the intake air amount of the intake pipe. And the intake pressure of the intake pipe can be approximated to the actual state, and the intake air amount or the intake pressure can be accurately calculated. Further, since the intake air amount or the intake pressure is calculated based on the relational expression, the calculation of the intake air amount or the intake pressure is simplified as compared with a map process or the like.

By setting the first relational expression and the second relational expression so that they pass through the same point, the first relational expression and the coefficient specifying the second relational expression can be changed even if the setting is changed. The continuity of the straight line according to the equation and the second relational equation is maintained, and the internal combustion engine can be appropriately controlled. Therefore, maintenance such as setting change can be easily performed. Further, it is possible to calculate the intake pressure back based on the intake air amount using the inverse function formula of the first relational expression and the second relational expression, and to calculate the intake air amount back based on the intake pressure.

Further, since the first relational expression and the second relational expression may be set as expressions having predetermined inclinations and passing through predetermined same points, the amount of set data may be small, and the memory capacity and the calculation load may be reduced. I can do it.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an internal combustion engine control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the internal combustion engine control device of FIG. 1;

FIG. 3 is a diagram showing a relationship between an intake air pressure Pm and an intake air amount Mc in an intake air amount calculation of the internal combustion engine control device of FIG. 1;

FIG. 4 is a diagram illustrating a relationship between a pressure ratio upstream and downstream of a valve and a reverse flow rate when there is valve overlap;

FIG. 5 is a flowchart showing an operation of the internal combustion engine control device according to the second embodiment.

FIG. 6 is a diagram illustrating a relationship between an intake pressure Pm and an intake air amount Mc in an intake air amount calculation of the internal combustion engine control device according to the second embodiment.

FIG. 7 is an explanatory diagram of continuity of a first relational expression and a second relational expression in the internal combustion engine control device according to the second embodiment.

FIG. 8 is a flowchart showing an operation of the internal combustion engine control device according to the third embodiment.

[Explanation of symbols]

2 ... Engine, 3 ... Intake valve, 4 ... Exhaust valve, 5 ... Variable valve timing mechanism (variable valve operating mechanism), 6 ... ECU.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Haruhumi Muto 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G084 BA04 BA23 DA04 DA13 EA07 EA11 EB02 EC04 FA07 FA10 FA11 FA38 FA39 3G092 AA01 AA11 AB02 BA01 BA02 DA03 EA08 EA11 EA23 EB10 EC06 FA06 HA01Z HA05Z HA06Z HA13X HA13Z HE01Z HE03Z HE04Z 3G301 HA01 HA19 JA00 JA20 LA01 LA07 MA01 MA12 MA13 NA09 NB18 ND05 ND45 NE18 NE20 PA01Z PA07Z PA11Z03

Claims (6)

[Claims] 1. An internal combustion engine control device for calculating an amount of intake air to be taken into an internal combustion engine, wherein a determination is made as to whether an intake pressure of an intake pipe connected to the internal combustion engine is equal to or lower than a predetermined intake pressure. Means, and when the determination means determines that the intake pressure of the intake pipe is equal to or lower than a predetermined intake pressure, the intake air amount is determined based on a first relational expression that is a linear expression of the intake pressure of the intake pipe. A second expression that is a linear expression of the intake pressure of the intake pipe when the determination means determines that the intake pressure of the intake pipe is not lower than a predetermined intake pressure, and has a slope different from the first relational expression. A control unit for calculating the intake air amount based on a relational expression. 2. The first relational expression and the second relational expression are:
2. The internal combustion engine control device according to claim 1, wherein the predetermined intake pressure is set so as to pass through the same point in a coordinate system of the intake pressure and the intake air amount. 3. 3. An internal combustion engine control device for calculating an amount of intake air taken into an internal combustion engine, wherein a determination is made as to whether an intake pressure of an intake pipe connected to the internal combustion engine is equal to or lower than a predetermined intake pressure. Means for calculating the intake air amount based on a linear expression of the intake pressure of the intake pipe when the determination means determines that the intake pressure of the intake pipe is equal to or lower than a predetermined intake pressure; Computing means for calculating the intake air amount based on a quadratic or higher expression of the intake pressure of the intake pipe when it is determined that the intake pressure of the intake pipe is not lower than a predetermined intake pressure. An internal combustion engine control device characterized by the above-mentioned. 4. An internal combustion engine control device for calculating an intake pressure of an intake pipe connected to an internal combustion engine, wherein it is determined whether an intake air amount taken into the internal combustion engine is equal to or less than a predetermined intake air amount. Determining means, and a first expression which is a linear expression of the amount of intake air taken into the internal combustion engine when it is determined that the amount of intake air taken into the internal combustion engine is equal to or less than a predetermined amount of intake air. Calculating the intake air pressure based on a relational expression, and when the determination means determines that the amount of intake air to be taken into the internal combustion engine is not less than a predetermined intake air amount, the amount of intake air taken into the internal combustion engine Calculating means for calculating the intake pressure based on a second relational expression having a gradient different from that of the first relational expression. 5. The first relational expression and the second relational expression are:
5. The internal combustion engine control device according to claim 4, wherein the predetermined intake air amount is set so as to pass through the same point in a coordinate system of the intake pressure and the intake air amount. 6. The internal combustion engine control device according to claim 1, wherein the internal combustion engine includes a variable valve mechanism.