JPH09287507A - Throttle valve controller for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitates a throttle valve control which corresponds to variation in the density of intake air and is highly accurate by correcting a target opening of a throttle valve set up on engine operating conditions on the basis of the presumed density of the intake air in case of controlling the opening of the throttle valve. SOLUTION: A control unit 13 first computes a target torque of an engine on accelerator control input expressed by an accelerator opening sensor 1 and a car speed expressed by a car speed sensor 2 during the operation of the car. Next a target fuel quantity and a target air/fuel ratio are computed on an engine target torque and an engine revolution speed through a map retrieval. Next the above target fuel quantity and air/fuel ratio are multiplied to compute a target intake air quantity into a cylinder, and the first, the second and the third coefficients of compensation are computed on the outputs of an atmospheric pressure sensor 11, of an intake temperature sensor 12 and of an EGR gas temperature sensor 24, and a target opening area computed on the engine revolution speed and the target air quantity is compensated by each coefficient of compensation to obtain the opening control quantity of the throttle valve 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle valve control device for an internal combustion engine, and more particularly to a technique for controlling a throttle valve with high accuracy so as to obtain a target air amount.

[0002]

2. Description of the Related Art Conventionally, the opening of a throttle valve is electronically controlled so as to obtain a target air amount on the basis of an engine operating condition such as an accelerator operation amount (accelerator pedal depression amount) or the engine rotation speed. There is a technology that I did. Further, there is also a technique provided with the electronic throttle valve control device, in which a target torque of the engine is set, and a fuel supply amount and a target air amount to the engine are set so as to obtain the target torque. .

On the other hand, it is known that the air-fuel ratio is controlled while being varied over a wide range based on engine operating conditions.

[0004]

However, the conventional throttle valve control device does not consider the fact that the intake air amount changes depending on the intake air density even if the throttle valve opening is the same. When the atmospheric pressure decreases and the density of the intake air decreases, it has not been possible to quickly control the throttle valve opening to obtain the target air amount.

Therefore, even if a method of setting the target torque and rapidly controlling the supplied fuel amount and the air amount at the same time so as to obtain the target torque is adopted, the target torque is quickly controlled. However, the merit of the method, especially the improvement of the transient operation performance, cannot be sufficiently obtained. The present invention has been made in view of such conventional problems, and an object of the present invention is to enable highly accurate throttle valve control in response to changes in the density of intake air.

Another object of the present invention is to make it possible to perform throttle valve control with higher accuracy by estimating the density of the intake air with high accuracy.

[0007]

Therefore, in the invention according to claim 1, as shown by the solid line in FIG. 1, the opening degree of the throttle valve interposed in the intake system is controlled based on the engine operating condition. In a throttle valve control device for an internal combustion engine, an air density estimating means for estimating the density of intake air, and a target opening degree of a throttle valve set based on engine operating conditions, based on the estimated intake air density. The throttle valve control means for correcting and controlling is included.

The invention according to claim 2 is characterized in that the air density estimating means detects or estimates the atmospheric pressure and estimates the atmospheric density based on the atmospheric pressure. In the invention according to claim 3, the air density estimating means includes means for detecting a temperature of intake air, and the intake air is inhaled based on the detected or estimated atmospheric pressure and the detected intake air temperature. The feature is that the density of air is estimated.

Further, in the invention according to claim 4, the air density estimating means estimates the density of the intake air estimated based on at least the atmospheric pressure by correcting the density of the intake air based on the temperature rise due to the EGR gas during the EGR control. It is characterized by being Further, the invention according to claim 5 is, as shown by the one-dot chain line in FIG. 1, accelerator operation amount detecting means for detecting an accelerator operation amount, vehicle speed detecting means for detecting a vehicle speed, and the detected accelerator operation amount. Target torque setting means for setting the target torque of the engine based on the vehicle speed, engine speed detecting means for detecting the engine speed, and to the engine based on the set target torque and the detected engine speed. Target fuel amount setting means for setting the target fuel amount to be supplied, target air-fuel ratio setting means for setting the target air-fuel ratio of the combustion mixture, and target air based on the set target fuel amount and target air-fuel ratio A target air amount setting means for setting an amount, and a target opening amount setting means for setting a target opening amount based on the set target air amount and the detected engine rotation speed are included. Special To.

[0010]

According to the first aspect of the present invention, the target opening of the throttle valve, which is set according to the engine operating condition, is corrected by the estimated intake air density and controlled, so that the vehicle travels at high altitude. Even if the intake air density changes with time and the intake air amount changes with respect to the same throttle valve opening, the influence of the change in intake air density is corrected to control the opening to obtain the target air amount. can do.

Further, according to the second aspect of the present invention, since the density of the intake air is most affected by the change in the atmospheric pressure, the intake air density can be estimated by detecting or estimating the atmospheric pressure. . Further, according to the invention of claim 3, the density of the intake air changes depending on not only the atmospheric pressure but also the temperature of the intake air. Therefore, the density of the intake air estimated based on the atmospheric pressure is It is possible to perform the estimation with higher accuracy by correcting and estimating with the detected intake air temperature.

According to the invention of claim 4, EG
During R control, EGR gas is sucked together with fresh air and the air temperature rises, so that the air density decreases. Therefore, by performing the correction based on the temperature rise due to the EGR gas, the influence of EGR can be removed and the density of the intake air can be accurately estimated.

Further, according to the invention of claim 5, in which the target torque and the target air-fuel ratio of the engine are set and the throttle valve opening is controlled so that the target torque and the target air-fuel ratio are satisfied, By performing the correction based on the intake air density, the compatibility between the driving performance and the exhaust gas purification performance can be improved as much as possible even when traveling at high altitudes.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system configuration (common to each control embodiment to be described later) of an embodiment of the present invention. Accelerator opening sensor 1 as accelerator operation amount detection means
Detects the amount of depression of the accelerator pedal depressed by the driver.

The crank angle sensor 2 as an engine rotational speed detecting means generates a position signal for each unit crank angle and a reference signal for each cylinder stroke phase difference, and measures the number of generated position signals per unit time. Or by measuring the reference signal generation cycle, the engine speed can be detected. The air flow meter 3 is the engine 4
The amount of intake air (intake air amount per unit time = intake air flow rate) is detected.

The water temperature sensor 5 detects the cooling water temperature of the engine. The engine 4 is provided with a fuel injection valve 6 that is driven by a fuel injection signal and directly injects fuel into the combustion chamber, and a spark plug 7 that is mounted in the combustion chamber and ignites. By the direct injection method into the combustion chamber, leaning by stratified combustion becomes possible, and the air-fuel ratio can be variably controlled over a wide range. A throttle valve 9 is provided in the intake passage 8 of the engine 4, and a throttle valve control device 10 capable of electronically controlling the opening of the throttle valve 9 is provided. Further, the intake passage 8 is provided with an atmospheric pressure sensor 11 that detects the atmospheric pressure and an intake temperature sensor 12 that detects the temperature of the intake air upstream of the throttle valve 9. The atmospheric pressure may be estimated from the engine operating condition. For example, the opening of the throttle valve controlled for the same target torque may be stored and the atmospheric pressure can be estimated from the change in the opening. Is. In addition, when applying to the method of calculating the target fuel amount according to the detected value of the intake pressure, the value of the intake pressure sensor provided on the downstream side of the throttle valve is set to a predetermined value when the engine is stopped or the throttle valve opening degree is a predetermined value. The detected value in the above case can be used as the atmospheric pressure detected value.

Further, a vehicle speed sensor 13 for detecting the vehicle speed is provided. Detection signals from the various sensors are input to the control unit 14, and the control unit 14
Reference numeral 14 controls the opening of the throttle valve 9 via the throttle valve control device 10 according to the operating state detected based on the signals from the sensors and drives the fuel injection valve 6 to inject fuel. The amount (fuel supply amount) is controlled, the ignition timing is set, and the ignition plug 7 is ignited at the ignition timing.

An EGR passage 22 connecting the exhaust passage 21 and the intake passage 8 of the engine 1 and an EGR valve 23 interposed in the EGR passage 22 are provided, and the control unit is provided.
With EGR, EGR is performed in a predetermined region represented by the engine rotation speed Ne and the engine load (represented by the fuel injection amount, etc.) to obtain the target EGR rate (EGR amount / intake air flow rate). The opening degree of the valve 22 is controlled. Also, the EG
An EGR gas temperature sensor 24 that detects the EGR gas temperature is provided in the EGR passage 22 downstream of the R valve 23, and as described later, during EGR control, the throttle valve opening degree is corrected by the temperature increase due to EGR.

Next, one embodiment of the throttle valve control according to the present invention will be described with reference to the flowcharts of FIGS. 3 and 4. In step 1, the engine required to obtain the target driving force of the vehicle based on the accelerator operation amount (accelerator pedal depression amount) Acc detected by the accelerator opening sensor 1 and the vehicle speed VSP by the vehicle speed sensor 2. The target torque tTe of is calculated.

In step 2, the target torque t of the engine is
Based on Te and the engine rotation speed Ne calculated based on the detection signal from the crank angle sensor 2, the target fuel amount tQf is calculated by searching a map as shown in the figure or the like. In step 3, the target air-fuel ratio tA / F is calculated based on the target torque tTe and the engine rotation speed Ne by searching a map as shown in the figure.

In step 4, the target fuel amount tQf
And the target air-fuel ratio tA / F are multiplied to calculate the target air amount tQa taken into the cylinder. In step 5, based on the atmospheric pressure detected by the atmospheric pressure sensor 11, a first correction coefficient K1 for correcting the throttle valve opening degree according to the intake air density is retrieved from a map as shown in the figure. Etc.

Here, the correction coefficient K1 is set to be small in order to correct the throttle valve opening so that the air density increases as the atmospheric pressure increases, as shown in the figure. In step 6, a second correction coefficient K1 for correcting the throttle valve opening is calculated based on the temperature of the intake air detected by the intake air temperature sensor 12 by searching a map as shown in the figure or the like. .

Here, the correction coefficient K2 is set to be large in order to increase and correct the throttle valve opening because the air density decreases as the intake air temperature increases as shown in the figure. In step 7, based on the EGR gas temperature detected by the EGR gas temperature sensor 24, a third correction coefficient K3 for correcting the temperature increase amount of the throttle valve opening due to the EGR gas is set to the map as shown in the figure. Calculate by searching from.

Here, as the EGR gas temperature rises, the temperature rise of the intake air due to the EGR gas increases and the air density decreases. Therefore, the throttle valve opening is set to be increased so as to be corrected. There is. In step 8, based on the engine speed Ne and the target air amount tQa, by a search from a map as shown,
The target opening area tAa of the throttle valve is calculated.

In step 9, the target opening area tAa is set.
Is corrected by multiplying the first correction coefficient K1, the second correction coefficient K2, and the third correction coefficient K3 for correcting the throttle valve opening based on the intake air density estimation set as described above. The target opening area tETC is calculated. Step 10
Then, the opening control amount tTVO of the throttle valve that obtains the corrected target opening area tETC is calculated by a search or the like from a map as shown.

In step 11, the signal of the opening control amount tTVO thus obtained is sent to the throttle valve control device 10.
Output to As a result, the throttle valve 9 is controlled to the set opening degree tTVO and the target air amount is obtained. By doing this, even if the density of the intake air changes during high-altitude traveling, the target air amount is corrected with high accuracy by performing the correction according to the density, and the corrected air amount is obtained. The throttle valve opening can be rapidly corrected and controlled.

Further, the fuel amount is set by dividing the target air amount thus corrected by the target air-fuel ratio tA / F. As a result, it is possible to control the air amount and the fuel amount according to the air density with high accuracy while always satisfying the target air-fuel ratio tA / F and to correct the target torque tTe. The compatibility between purification performance and operation performance can be improved as much as possible.

It should be noted that in the case where the target torque is set as in the present embodiment, the engine operating performance, especially the transient operating performance can be further improved, but the present invention is sufficiently applicable to the case where the target torque is not set. It is effective. Further, in the case where the target air-fuel ratio is variably controlled, particularly in the case where the air-fuel ratio is variably controlled by a direct fuel injection system, the actual air-fuel ratio can follow the variable target air-fuel ratio with high accuracy. Although it is particularly advantageous, it is sufficiently effective when applied to a device having a limited air-fuel ratio control range.

Further, in the present embodiment, since the correction amount of the throttle valve opening degree by the EGR gas is set by detecting the EGR gas temperature, the temperature rise of the intake air due to the EGR gas is estimated with high accuracy, and it is favorable. You can make corrections,
In a simple manner, the EGR control may be performed by multiplying by a uniform correction coefficient for correction.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing a preceding stage of a throttle valve control routine of the same embodiment.

FIG. 4 is a flowchart showing a latter stage of the above-mentioned routine.

[Explanation of symbols]

 1 accelerator operation amount sensor 2 crank angle sensor 3 air flow meter 4 engine 5 water temperature sensor 6 fuel injection valve 9 throttle valve 10 throttle valve control device 11 atmospheric pressure sensor 12 intake air temperature sensor 13 vehicle speed sensor 14 control unit 22 EGR passage 23 EGR valve 24 EGR gas temperature sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02D 41/04 310 310 F02D 41/04 310Z 330 330A 45/00 312 45/00 312P 360 360E F02M 25 / 07 550 F02M 25/07 550R

Claims (5)

[Claims] 1. A throttle valve control device for an internal combustion engine, which controls an opening of a throttle valve interposed in an intake system based on engine operating conditions, and air density estimating means for estimating a density of intake air; A throttle valve control means for correcting and controlling a target opening degree of a throttle valve set on the basis of the condition based on the estimated intake air density, and an internal combustion engine characterized by the following: Throttle valve control device. 2. The throttle valve for an internal combustion engine according to claim 1, wherein the air density estimating means detects or estimates atmospheric pressure and estimates the atmospheric density based on the atmospheric pressure. Control device. 3. The air density estimating means includes means for detecting the temperature of intake air, and estimates the density of intake air based on the detected or estimated atmospheric pressure and the detected intake air temperature. 2. The method according to claim 2, wherein
A throttle valve control device for an internal combustion engine according to item 1. 4. The air density estimating means estimates at least the density of intake air estimated on the basis of atmospheric pressure by correcting it on the basis of a temperature rise due to EGR gas during EGR control. The throttle valve control device for an internal combustion engine according to any one of claims 1 to 3. 5. An accelerator operation amount detecting means for detecting an accelerator operation amount, a vehicle speed detecting means for detecting a vehicle speed, and a target torque setting for setting a target torque of an engine based on the detected accelerator operation amount and the vehicle speed. Means, an engine speed detecting means for detecting an engine speed, and a target fuel amount setting means for setting a target fuel amount to be supplied to the engine based on the set target torque and the detected engine speed. , Target air-fuel ratio setting means for setting a target air-fuel ratio of the combustion mixture, target air amount setting means for setting a target air amount based on the set target fuel amount and target air-fuel ratio, and the set 5. A target opening degree setting means for setting a target opening degree based on the target air amount and the detected engine rotation speed, and any one of claims 1 to 4. One A throttle valve control device for an internal combustion engine according to item 1.