JPH0835441A - Throttle opening control method - Google Patents

Abstract

PURPOSE:To generate proper torque without lowering a travel speed by increasing the volume of the intake air flowing to an intake system for the degree of stepping down an accelerator pedal, as compared with an intake air volume for a theoretical air-fuel ratio, in the operation state of an internal combustion engine at an air-fuel ratio larger than the theoretical air-fuel ratio. CONSTITUTION:An electronic control device 6 determines a fuel injection throttle opening time and controls a fuel injection valve 5, on the basis of each of output (a) and (b) of an intake air pressure sensor 13 and an engine speed sensor 14, or various types of correction factors. In this case, device 6 detects the stepping degree (d) of an accelerator pedal, so as to maintain a theoretical air-fuel ratio and a larger air-fuel ratio, depending on the load of an engine 100. Also, when operation state is based on the air-fuel ratio larger than the theoretical air-fuel ratio, the opening of a throttle valve 2 is controlled, so as to increase an intake air volume relative to the stepping degree (d) of the accelerator, compared with the case of the theoretical air-fuel ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle opening control method for an internal combustion engine for an automobile, which is operated in a lean burn region where the air-fuel ratio is high.

[0002]

2. Description of the Related Art In recent years, in order to improve fuel efficiency and purify exhaust gas, there is a rapid increase in the need to operate the engine with the air-fuel ratio leaner than the theoretical air-fuel ratio. Further, in relation to traction control, etc., the accelerator pedal and the throttle valve are not mechanically interlocked, but the accelerator pedal depression is detected and the throttle valve opening is controlled in accordance with the depression. It is also known to have a configuration. For example, as in a throttle valve control device for an engine described in Japanese Patent Laid-Open No. 4-140437, an accelerator pedal operation amount is detected by an accelerator opening sensor, and a throttle valve opening is calculated according to the detected accelerator opening. Then
It is known that a throttle valve is driven by a motor based on the opening obtained by calculation.

[0003]

Generally, the opening degree of the throttle valve differs in order to generate the same torque in the operating state at the stoichiometric air-fuel ratio, that is, in the stoichiometric operation and the lean burn operation. That is, as shown in FIG. 4, for example, during lean burn operation, the same torque is not generated unless the accelerator pedal is depressed more than in stoichiometric operation, that is, the opening of the throttle valve is increased. This means that when the stoichiometric operation is switched to the lean burn operation, the torque is reduced when the accelerator pedal is not depressed, the traveling speed is reduced, and the operation interval is different from the stoichiometric operation.

However, in the above arrangement, the degree of depression of the accelerator pedal is detected by the accelerator opening sensor and the opening of the throttle valve is calculated in accordance with the degree of depression, so that the operating state changes. Throttle valve opening does not change. Therefore, torque down may occur, and as a result, the traveling speed may decrease.

[0005] An object of the present invention is to solve such a problem.

[0006]

In order to achieve the above object, the present invention takes the following measures. That is, the throttle opening control method according to the present invention, the stoichiometry of the accelerator pedal is detected so that the stoichiometric air-fuel ratio and the air-fuel ratio are higher than the stoichiometric air-fuel ratio depending on the state of the load of the internal combustion engine, A throttle opening control method for controlling the opening of a valve body that adjusts an intake air amount provided in an intake system of an internal combustion engine according to the pedaling, by detecting and detecting an operating state of the internal combustion engine. When the operating state is an operating state at an air-fuel ratio higher than the theoretical air-fuel ratio, the valve body is configured to increase the amount of intake air flowing into the intake system with respect to the accelerator pedal depression degree as compared to the case of the theoretical air-fuel ratio. Is controlled.

[0007]

With this structure, when the operating state at the stoichiometric air-fuel ratio is switched to the operating state at an air-fuel ratio higher than the stoichiometric air-fuel ratio, that is, lean burn operation,
The valve element of the intake system is controlled so that the intake air amount is increased as compared with the operating state at the stoichiometric air-fuel ratio. That is, when the accelerator pedal depression is the same in the two operating states, the opening degree of the valve body is large in the lean burn operation, and the intake air amount is increased as compared with the stoichiometric air-fuel ratio. Therefore,
It is possible to generate torque equivalent to that in the case of the stoichiometric air-fuel ratio, without changing the degree of depression of the accelerator pedal when switching to lean burn operation. Therefore, the traveling speed does not decrease and the drive feeling does not deteriorate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 schematically shown in FIG. 1 is for an automobile, and its intake system 1 has a step motor 16
A throttle valve 2 which is driven to open and close by
A surge tank 3 is provided on the downstream side. The step motor 16 is based on a pedal signal d output from an accelerator pedal sensor (not shown) that detects the pedal depression of an accelerator pedal (not shown). Open and close the throttle valve 2. The accelerator pedal sensor may be one that outputs an analog voltage proportional to the degree of depression of the accelerator pedal, such as a potentiometer, like the throttle sensor. A fuel injection valve 5 is further provided near one end of the intake manifold 4 of the intake system 1 communicating with the surge tank 3, and the fuel injection valve 5 is controlled by the electronic control unit 6. . Further, a lean sensor 21 for measuring the oxygen concentration in the exhaust gas is attached to the exhaust system 20 at a position upstream of a three-way catalyst 22 arranged in a pipe line leading to a muffler (not shown). .
The lean sensor 21 has substantially the same structure as a normal O ₂ sensor, and in the case of a theoretical air-fuel ratio under feedback control by applying a constant voltage between the atmosphere side electrode and the exhaust side electrode. Thus, a current corresponding to the oxygen concentration in the exhaust gas is output over the air-fuel ratio in the lean burn region.

The electronic control unit 6 includes a central processing unit 7
And a storage device 8, an input interface 9, and an output interface 11 are mainly configured. Electronic control unit 6
To the input interface 9 of the intake tank, the intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the surge tank 3, and the rotation speed output from the rotation speed sensor 14 for detecting the engine speed NE. A signal b, a vehicle speed signal c output from a vehicle speed sensor 15 for detecting the vehicle speed,
The pedal signal d output from the accelerator pedal sensor for detecting the accelerator pedal depression, the water temperature signal e from the water temperature sensor 17 for detecting the engine cooling water temperature, and the voltage from the lean sensor 21. The signal h or the like is input. On the other hand, from the output interface 11, the fuel injection signal f is sent to the fuel injection valve 5, the ignition pulse g is sent to the spark plug 18, and the opening / closing drive signal j is sent to the step motor 16 for opening / closing the throttle valve 2. , Are output respectively.

The electronic control unit 6 has an intake pressure signal a output from the intake pressure sensor 13 and a rotation speed signal b output from the rotation speed sensor 14 as main information, and various kinds of information are determined depending on the engine condition. The fuel injection valve opening time, that is, the injector final energization time T is determined by correcting the basic injection time with the correction coefficient, and the fuel injection valve 5 is controlled according to the determined energization time to supply the fuel according to the engine load. A program for injecting from the injection valve 5 to the intake system 1 is built in. In this program, the engine 100
The accelerator pedal depression degree is detected so that the stoichiometric air-fuel ratio becomes larger than the stoichiometric air-fuel ratio depending on the load state of the engine, and the intake system 1 of the engine 100 is provided according to the depression degree. It controls the opening of the throttle valve 2 which is a valve body for adjusting the intake air amount, detects the operating state of the engine 100, and the detected operating state is an operating state at an air-fuel ratio higher than the theoretical air-fuel ratio. In this case, the opening degree of the throttle valve 2 is programmed so as to increase the amount of intake air flowing into the intake system 1 with respect to the depression degree of the accelerator pedal as compared with the case of the theoretical air-fuel ratio.

The outline of this throttle opening control program is as shown in FIG. However, as the program itself for calculating the effective injection time TAU in consideration of various correction factors and then calculating the injector final energization time T, a conventionally known program can be used, and therefore, illustration and description thereof will be omitted.

First, in step S1, the step signal d of an analog signal output from the accelerator pedal sensor is set to A /
D conversion is performed to obtain digital data of the accelerator pedal depression degree. In step S2, the engine 100 at that time
Determine whether the operating state of is lean burn operation,
If it is in the lean burn operation state, the process proceeds to step S3. If not, that is, in the stoichiometric operation state of operating at the stoichiometric air-fuel ratio, the process proceeds to step S5. In step S3, the control throttle opening in the lean burn operation state is calculated. The control throttle opening is separately set for stoichiometric operation and lean burn operation.
The control throttle opening is preset in the two-dimensional map with respect to the accelerator pedal depression degree. As shown in FIG. 3, each throttle opening is set to change linearly with respect to the accelerator pedal depression, and the control throttle opening during lean burn operation is the one during stoichiometric operation. Compared with the above, it is set so that it opens greatly when the accelerator pedal depression degree is the same. In step S4, the step motor 16 for driving the throttle valve 2 is controlled based on the calculated control throttle opening. In step S5, the control throttle opening in the stoichiometric operation state is calculated.

In such a configuration, when the vehicle is running in stoichiometric operation and the operating condition satisfies the lean burn operating condition, the opening of the throttle valve 2 changes even if the accelerator pedal does not change. To do. In other words, if the vehicle is held with the accelerator pedal held at a certain degree, the operating state of the engine will cease to be a transient state.
The lean burn operation conditions are satisfied. The determination condition of the lean burn operation may be determined by, for example, the engine speed, the magnitude of the load, the cooling water temperature, etc., the engine is starting, the warm-up amount is being increased during the warm-up operation,
It is set so that it can be determined that the engine is in a steady state, except when it is in a transient state such as during acceleration. In this case, the control is steps S1 → S2 → S3 →
The program proceeds to S4, the accelerator pedal depression at that time is detected, the control throttle opening during lean burn operation is calculated, and the opening of the throttle valve 2 is controlled according to the calculated throttle opening. In the relationship shown in FIG. 3, for example, when the stoichiometric operation with the accelerator pedal being 40 degrees is changed to the lean burn operation, the control throttle opening is increased from about 38 degrees to about 63 degrees. As a result, the amount of air flowing into the intake system 1 is increased by increasing the opening degree of the throttle valve 2 and the torque is not reduced, which is the same as the feeling during stoichiometric operation without changing the accelerator pedal depression degree. You can drive with a feeling.

On the other hand, when the accelerator pedal is depressed to accelerate the vehicle from the stoichiometric operation state or decelerate from the stoichiometric operation state, the stoichiometric operation condition is no longer satisfied, and the control proceeds to steps S1 → S2 → S5 → S4. in this case,
For example, although the degree of depression of the accelerator pedal is changed, the control throttle opening for stoichiometric operation is calculated at the time when it is determined to be in a transient state, so the control throttle opening is reduced as compared to that time. Therefore, the intake air amount is smaller when the accelerator pedal is the same than when the lean burn operation is performed, and the operating state can be switched during the stoichiometric operation without the air-fuel ratio becoming lean.

The present invention is not limited to the embodiment described above. In the above embodiment, the case where the throttle valve 2 is applied to the engine configured to be driven by the step motor has been described. However, the throttle valve and the accelerator pedal are mechanically connected by a wire and bypass the throttle valve. It may be applied to a structure in which a sub-throttle valve including a large capacity linear valve is provided in the bypass passage. That is, in the engine having such a configuration, the throttle valve is mechanically controlled by the depression operation of the accelerator pedal,
The sub throttle valve is configured to be electrically controlled by, for example, a step motor. In this case, the throttle valve is provided with a throttle sensor that continuously outputs an electric signal according to the opening of the throttle valve, and the accelerator pedal sensor is not used.

In such a configuration, when the stoichiometric operation state is changed to the lean burn operation state, the opening of the throttle valve does not change, but the sub-throttle valve is the throttle opening calculated similarly to the throttle valve of the above-mentioned embodiment. The opening degree is controlled based on the degree. In this case, since the opening of the throttle valve is detected by the throttle sensor, the sub-throttle valve may be controlled by the opening corresponding to the difference in the opening due to the change in the operating state. In this way, even if the amount of air passing through the bypass passage is controlled to control the amount of intake air when the operating state changes, the same effect as in the above embodiment can be obtained. A large capacity VSV (vacuum switching valve) may be used as the sub-throttle valve.

In addition, the configuration of each part is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0019]

As described in detail above, the present invention controls the opening degree of the valve body according to the operating state at that time even if the operating state changes. It is possible to obtain an appropriate torque in each driving state without changing the driving condition, and to prevent the driving feeling from changing each time the driving state is switched.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is an operation explanatory view of the same embodiment.

FIG. 4 is an explanatory view of the operation of a conventional example.

[Explanation of symbols]

 1 ... Intake system 2 ... Throttle valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Storage device 9 ... Input interface 11 ... Output interface

Claims (1)

[Claims] 1. The accelerator pedal depression is detected so that a stoichiometric air-fuel ratio and an air-fuel ratio larger than the stoichiometric air-fuel ratio are obtained according to the load state of the internal combustion engine, and the internal combustion engine is detected according to the depression degree. Is a throttle opening degree control method for controlling the opening degree of a valve body that adjusts the intake air amount provided in the intake system, the operating state of the internal combustion engine being detected, and the detected operating state is greater than the theoretical air-fuel ratio. It is possible to control the opening degree of the valve element so that the intake air amount flowing into the intake system with respect to the accelerator pedal depression degree in the operating state at the air-fuel ratio A characteristic throttle opening control method.