JP3284395B2 - Throttle valve control device for internal combustion engine - Google Patents

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, based on operating conditions of an engine, for example, an accelerator operation amount (accelerator pedal depression amount) or an engine speed, the throttle valve opening is electronically controlled so as to obtain a target air amount. There is a technology that has been made. In addition, there is a technology that includes the electronic throttle valve control device, sets a target torque of the engine, and sets a fuel supply amount to the engine and a target air amount so as to obtain the target torque. .

[0003] On the other hand, there has been known a method of controlling the air-fuel ratio while changing it over a wide range based on engine operating conditions.

[0004]

However, the conventional throttle valve control device does not take into account that the intake air amount changes even at the same throttle valve opening degree depending on the intake air density. When the air 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.

[0005] For this reason, even if a method is used in which the target torque is set and the supplied fuel amount and the air amount are simultaneously and quickly controlled so as to obtain the target torque, the target torque is quickly controlled. As a result, it was not possible to sufficiently bring out the merits of the method, especially the improvement of the transient operation performance. The present invention has been made in view of such conventional problems, and has as its object to perform throttle valve control with high accuracy in response to a change in the density of intake air.

It is another object of the present invention to perform throttle valve control with higher accuracy by estimating the density of the intake air with high accuracy.

[0007]

According to the first aspect of the present invention, as shown by a solid line in FIG. 1, the opening of a throttle valve interposed in an intake system is controlled based on engine operating conditions. In a throttle valve control device for an internal combustion engine, the density of intake air is determined based on at least detected or estimated atmospheric pressure.
Estimated and the temperature due to EGR gas during EGR control
Air density estimating means for correcting and estimating based on the rise, and a throttle valve for correcting and controlling the target opening of the throttle valve set based on the engine operating conditions based on the estimated intake air density And control means.

[0008] The invention according to claim 2 is the airtightness.
The degree estimating means includes means for detecting the temperature of the intake air ,
Based on the detected or estimated atmospheric pressure and the detected intake air temperature, estimate the density of the intake air , and
During EGR control, compensation is performed based on temperature rise due to EGR gas.
And characterized in that a positive to.

The invention according to a third aspect of the present invention provides an accelerator operation amount detecting means for detecting an accelerator operation amount, a vehicle speed detecting means for detecting a vehicle speed, as shown by a dashed line in FIG. Target torque setting means for setting a target torque of the engine based on the manipulated variable and the vehicle speed; engine speed detecting means for detecting the engine speed; and based on the set target torque and the detected engine speed. Target fuel amount setting means for setting a target fuel amount to be supplied to the engine, target air-fuel ratio setting means for setting a target air-fuel ratio of the combustion air-fuel mixture, and a target air-fuel ratio based on the set target fuel amount and target air-fuel ratio. Target air amount setting means for setting a target air amount by
And a target opening setting means for setting a target opening based on the set target air amount and the detected engine rotation speed.

[0010]

According to the first aspect of the present invention, high-altitude traveling is achieved by correcting and controlling the target opening of the throttle valve set in accordance with the engine operating conditions based on the estimated intake air density. Even when the density of the intake air changes at the same time and the intake air amount changes for the same throttle valve opening, the influence of the change in the intake air density is corrected to control the opening to obtain the target air amount. can do.

Since the density of the intake air is most affected by changes in the atmospheric pressure, the density of the intake air is estimated by detecting or estimating the atmospheric pressure.
Since the air density decreases as the GR gas is sucked in with the fresh air and the air temperature rises, the correction based on the temperature rise by the EGR gas is performed to remove the influence of the EGR and to accurately adjust the density of the intake air. Can be estimated well.

[0012] According to the second aspect of the present invention, further,
In addition, the density of the intake air depends on the change in the temperature of the intake air.
Also changes, the intake air estimated based on the atmospheric pressure
The density of air with the detected intake air temperature
Thereby, estimation can be performed with higher accuracy.

According to the third aspect of the present invention, 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 enhanced as much as possible even during high altitude traveling.

[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 detecting means
Detects the depression amount of the accelerator pedal depressed by the driver.

A crank angle sensor 2 as an engine 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 the position signals generated per unit time. Or by measuring the reference signal generation cycle, the engine speed can be detected. The air flow meter 3 is an engine 4
Detects the amount of intake air to the air (intake air amount per unit time = intake air flow rate).

The water temperature sensor 5 detects the temperature of the cooling water of the engine. The engine 4 is provided with a fuel injection valve 6 that is driven by a fuel injection signal and supplies fuel directly into the combustion chamber, and an ignition 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 interposed 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 for detecting the atmospheric pressure and an intake air temperature sensor 12 for detecting the temperature of the intake air, on the upstream side of the throttle valve 9. The atmospheric pressure may be estimated from the engine operating conditions. For example, the opening of the throttle valve controlled for the same target torque is stored, and the atmospheric pressure can be estimated from a change in the opening. It is. When applying to a method of calculating the target fuel amount in accordance with the detected value of the intake pressure, the value of the intake pressure sensor provided downstream of the throttle valve is set to a predetermined value when the engine is stopped or the throttle valve opening is set to a predetermined value. The detection value at the time described above can be used as the atmospheric pressure detection value.

Further, a vehicle speed sensor 13 for detecting a vehicle speed is provided. Detection signals from the various sensors are input to the control unit 14 and the control unit 14
14 controls the opening of the throttle valve 9 via the throttle valve control device 10 in accordance with the operating state detected based on the signals from the sensors, drives the fuel injection valve 6 and controls the fuel injection. 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.
13, EGR is performed in a predetermined region represented by the engine speed Ne and the engine load (represented by the fuel injection amount or the like), and the EGR is performed so that the target EGR rate (EGR amount / intake air flow rate) is obtained. The opening of the valve 22 is controlled. Further, the EG
An EGR gas temperature sensor 24 for detecting an EGR gas temperature is provided in an EGR passage 22 downstream of the R valve 23. As described later, at the time of EGR control, the throttle valve opening is corrected based on a temperature rise by the EGR.

Next, an embodiment of the throttle valve control according to the present invention will be described with reference to the flowcharts of FIGS. 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. Is calculated.

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

In step 4, the target fuel amount tQf
Is multiplied by the target air-fuel ratio tA / F to calculate a target air amount tQa drawn 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 corresponding to the intake air density is retrieved from a map as shown in the drawing. And so on.

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

Here, the correction coefficient K2 is set to be large so as to increase 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 rise of the throttle valve opening due to the EGR gas is calculated using a map as shown in the drawing. Calculated by searching from

Here, as the temperature of the EGR gas increases, 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 large in order to increase and correct the opening degree. I have. In step 8, based on the engine rotation speed Ne and the target air amount tQa, a search is performed from a map as shown in FIG.
The target opening area tAa of the throttle valve is calculated.

In step 9, the target opening area tAa
Is multiplied by a first correction coefficient K1, a second correction coefficient K2, and a 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 throttle valve opening control amount tTVO at which the corrected target opening area tETC is obtained is calculated by a search from a map as shown in FIG.

In step 11, the signal of the opening degree control amount tTVO obtained in this manner is applied to the throttle valve control device 10.
Output to Thus, the throttle valve 9 is controlled to the set opening degree tTVO, and the target air amount is obtained. In this way, even if the density of the intake air changes during traveling on high altitudes, the target air amount is corrected with high accuracy by performing correction according to the density, and the corrected air amount is obtained. Correction control can be quickly performed on the throttle valve opening to be performed.

The fuel amount is set by dividing the corrected target air amount by the target air-fuel ratio tA / F. As a result, the air amount and the fuel amount can be controlled with high accuracy while correcting the air amount and the fuel amount in accordance with the air density so as to secure the target torque tTe while always satisfying the target air-fuel ratio tA / F. The compatibility between the purification performance and the driving performance can be enhanced as much as possible.

In the case where the target torque is set as in the present embodiment, the engine operation performance, particularly the transient operation performance, can be further improved. However, 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 this embodiment, since the correction amount of the throttle valve opening 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 a good You can make corrections,
For simplicity, a configuration may be employed in which the correction is performed by multiplying by a uniform correction coefficient during the EGR control.

[Brief description of the 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 according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a first stage of a throttle valve control routine according to the embodiment;

FIG. 4 is a flowchart showing a latter part of the above routine.

[Explanation of symbols]

 DESCRIPTION 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 temperature sensor 13 Vehicle speed sensor 14 Control unit 22 EGR passage 23 EGR valve 24 EGR gas temperature sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 41/04 310 F02D 41/04 310Z 330 330A 45/00 312 45/00 312P 360 360E F02M 25/07 550 F02M 25/07 550R (56) References JP-A-2-291438 (JP, A) JP-A-6-129273 (JP, A) JP-A-2-185635 (JP, A) JP-A-5-288096 (JP, A) 60-47831 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/14 320 F02D 41/14 310 F02D 9/02 F02D 41/02 310 F02D 41/04 310 F02D 41/04 330 F02D 45/00 312 F02D 45/00 360 F02M 25/07 550

Claims (3)

(57) [Claims] A throttle valve control device for an internal combustion engine that controls the opening of a throttle valve interposed in an intake system based on engine operating conditions, wherein the density of intake air is at least detected or estimated.
And based on the EGR gas during the EGR control.
Air density estimating means for correcting and estimating based on the temperature rise, and controlling the target opening of the throttle valve set based on the engine operating conditions by correcting the target opening based on the estimated intake air density. A throttle valve control device for an internal combustion engine, comprising: throttle valve control means. 2. The air density estimating means includes means for detecting the temperature of the intake air, and estimates the density of the intake air based on the detected or estimated atmospheric pressure and the detected intake air temperature. And the EGR gas is used during the EGR control.
2. The throttle valve control device for an internal combustion engine according to claim 1 , wherein the correction is performed based on the temperature rise . 3. 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 the engine based on the detected accelerator operation amount and the vehicle speed. Means, an engine speed detecting means for detecting an engine speed, a target fuel amount setting means for setting a target fuel amount supplied to the engine based on the set target torque and the detected engine speed. A target air-fuel ratio setting means for setting a target air-fuel ratio of the combustion mixture; a target air amount setting means for setting a target air amount based on the set target fuel amount and the target air-fuel ratio; claim 1 also characterized in that it is configured to include a target opening setting means for setting a target opening based on the target air amount and the detected engine speed, the
A throttle valve control device for an internal combustion engine according to claim 2 .