JPH0654248B2 - Intake air amount detector for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount detection device for an internal combustion engine, and more particularly to an intake air amount detection device for an internal combustion engine for a vehicle equipped with a traction control system.

2. Description of the Related Art For example, in an internal combustion engine equipped with an electronically controlled fuel injection device as a fuel supply system, an intake air amount is detected by an air flow meter, which is a kind of flow meter, and based on this and the engine speed. , The fuel injection amount is controlled.

By the way, in recent years, in order to prevent slippage of the drive wheels during rain or when traveling on a low friction coefficient road such as a snow road, the slip of the drive wheels is detected from the comparison of the wheel rotation speeds, and the engine output is immediately output when the slip occurs. A traction control system has been developed that reduces the ground contact force to restore the ground contact force.

In this traction control system, an appropriate actuator, for example, a traction control throttle valve that is driven to open and close by an electric motor is provided in the intake passage of the engine in order to suppress the engine output when slip is detected. ing.

FIG. 5 shows this traction control throttle valve 1
1 schematically shows a main part of an intake passage 2 of an internal combustion engine equipped with a traction control throttle, which is generally provided upstream of a main throttle valve 3 whose opening is determined based on a driver's accelerator operation. A valve 1 is provided. Reference numeral 4 is a first throttle sensor for detecting the opening of the main throttle valve 3 which is opened / closed by an accelerator wire 5, and 6 is a throttle actuator including an electric motor for opening / closing the traction control throttle valve 1. , 7 are second throttle sensors for detecting the opening of the traction control throttle valve 1.

And, the air flow meter 8 including a hot wire type flow meter,
It is located on the downstream side of the traction control throttle valve 1, that is, between the traction control throttle valve 1 and the main throttle valve 3, and the air flow rate, that is, the engine intake air amount is detected here.

However, in the configuration in which the air flow meter 8 is arranged on the downstream side of the traction control throttle valve 1, the detection accuracy of the air flow meter 8 depends on the opening of the traction control throttle valve 1. Will be affected. This becomes remarkable especially in a type such as a hot wire type air flow meter which measures a flow rate in a minute range.

That is, as shown in FIG. 6, if the traction control throttle valve 1 is fully open, the air flow meter 8
Since the flow velocity distribution in the intake passage 2 in the vicinity is almost uniform,
Sufficient detection accuracy can be secured, but as shown in FIG.
When the opening degree of the traction control throttle valve 1 becomes smaller, the flow velocity distribution in the intake passage 2 near the air flow meter 8 is biased to the outside, and as a result, the flow rate is erroneously detected to be smaller than the actual flow rate. This measurement error increases as the opening θ of the traction control throttle valve 1 decreases, as shown in FIG. Since the control unit controls the fuel injection amount based on the detected flow rate, the actual air-fuel ratio becomes lean, which causes engine stall in an extreme case.

Means for Solving the Problems Therefore, in the present invention, a correction is added in accordance with the opening of the traction control throttle valve to avoid a decrease in detection accuracy. That is, as shown in FIG. 1, the intake air amount detecting device for an internal combustion engine according to the present invention is arranged on the upstream side of the main throttle valve A whose opening degree is determined based on the accelerator operation by the driver, depending on the vehicle traveling condition. In an internal combustion engine in which a traction control throttle valve B that is controlled to be opened and closed is disposed, an air flow meter C disposed between the main throttle valve A and the traction control throttle valve B, and the traction control throttle valve B And a means E for correcting the flow rate detected by the air flow meter C according to the opening degree of the traction control throttle valve B.

Action The measurement error of the intake air amount caused by the traction control throttle valve B has a certain characteristic according to the opening degree of the traction control throttle valve B, as described above, and the correction necessary to cancel it out. The amount can be experimentally determined in advance. Therefore, when the traction control throttle valve B is closed, the flow rate detected by the air flow meter C becomes lower than the actual flow rate, but by adding the correction according to the opening degree of the traction control throttle valve B, the influence is eliminated.

Embodiment One embodiment of the present invention will be described below. FIG. 2 is a configuration explanatory view showing the configuration of the control system of the whole vehicle including the intake air amount detecting device according to the present invention.

In the figure, 1 is a traction control throttle valve disposed in the intake passage 2 as described above, and 3 is a main throttle valve disposed downstream of the traction control throttle valve 1. A hot wire type air flow meter 8 is provided. The main throttle valve 3 is connected to an accelerator pedal 11 via an accelerator wire 5 so that the main throttle valve 3 is controlled to be opened and closed according to a driver's intention, and its opening is detected by a first throttle sensor 4. Has been done. The traction control throttle valve 1 is controlled to be opened / closed by a throttle actuator 6 composed of an electric motor or the like, and its opening is detected by a second throttle sensor 7. A fuel injection valve 12 is provided for each cylinder on the downstream side of the intake passage 2.

Next, an outline of a traction control system for controlling the opening / closing of the traction control throttle valve 1 will be described. This traction control system includes a pair of front wheel speed sensors 14 that detect the rotational speed of the front wheels 13, a pair of rear wheel speed sensors 16 that detect the rotational speed of the rear wheels 15, and the rotation of the front wheels 13 and the rear wheels 15. A traction control unit 17 that detects the slip of the driving wheels (in this case, the rear wheels 15) by comparing the speeds and outputs a target opening signal of the traction control throttle valve 1 according to the degree of the slip,
Based on this target opening signal and the detection signal of the second throttle sensor 7, the traction control throttle valve 1
And a drive circuit 18 for feedback controlling the throttle actuator 6. That is, when the rear wheel 15 slips on a snowy road or the like, the slip is immediately detected from the rotational speed difference between the front wheel 13 and the rear wheel 15, and the traction control throttle valve 1 is throttled to an appropriate opening degree. As a result, the output of the engine is reduced and the slip of the rear wheels 15 is suppressed. In addition,
The traction control unit 17 includes an engine speed signal detected by the engine speed sensor 19, a gear position of the transmission controlled by the A / T control unit 20, that is, an ON / OFF signal of the shift solenoid 21. Is also input, and the control characteristics of the traction control throttle valve 1 are corrected by these conditions.

Further, in this example, in order to prevent slipping at the same time when braking, the depression of the brake pedal 22 is detected by the brake switch 23, and when slip is detected, the brake hydraulic pressure is appropriately controlled via the traction hydraulic actuator 24. There is.

Next, 25 is the fuel injection amount control of the internal combustion engine (air-fuel ratio control)
It shows an engine control unit that controls the ignition timing and the like. This engine control unit 25
Is a digital microcomputer, calculates the engine intake air amount based on the detection signal of the air flow meter 8, and performs various controls with this and the engine rotation speed detected by the engine rotation speed sensor 19 as main parameters. There is.

FIG. 3 is a flowchart showing a processing procedure of air amount detection executed in the engine control unit 25. As shown in the figure, first, the air flow meter 8
The detected flow rate Q ₀ output by is read (step 1). Next, the opening θ of the traction control throttle valve 1 at that time is read (step 2). As the opening degree signal, the actual opening degree detected by the second throttle sensor 7 is input to the engine control unit 25 via the drive circuit 18. Then, the necessary correction amount is determined based on the opening degree θ of the traction control throttle valve 1 (step 3). This correction amount is given in advance as a table map in the engine control unit 25 according to the characteristics shown in FIG. 4, and the value corresponding to the opening degree θ at that time is sequentially read. Finally, this correction amount is added to the detected flow rate Q ₀ of the air flow meter 8 to obtain the actual flow rate Q, that is, the engine intake air amount (step 4).

That is, the correction is made according to the opening degree θ of the traction control throttle valve 1 so as to cancel the measurement error of the air flow meter 8 shown in FIG. 8. As a result, the traction control throttle valve 1 is opened. It is possible to detect the intake air amount with extremely high accuracy regardless of the degree.

Since the air-fuel ratio of the internal combustion engine, that is, the fuel injection amount is controlled based on the intake air amount and the engine rotation speed corrected as described above, the fluctuation of the air-fuel ratio even when the traction control throttle valve 1 is closed. Never come.

The correction calculation of the intake air amount may be performed simultaneously with the final calculation of the fuel injection amount.

As is apparent from the above description, in the intake air amount detection device for an internal combustion engine according to the present invention, the flow rate detected by the air flow meter is corrected according to the opening of the traction control throttle valve. The engine intake air amount can be detected with high accuracy regardless of the opening degree of the traction control throttle valve. Therefore, for example, it is possible to prevent the air-fuel ratio from becoming lean due to the error in the intake air amount.
Further, since the influence of the traction control throttle valve on the air flow meter can be eliminated in this way, the positions where the traction control throttle valve and the air flow meter are arranged are not restricted.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of the present invention, and FIG. 2 is a structural explanatory view showing an embodiment of the present invention. FIG. 3 is a flowchart showing a processing procedure of intake air amount detection in this embodiment. FIG. 4 is a characteristic diagram showing the characteristic of the correction amount in this embodiment, FIG. 5 is a sectional view of the main part of the intake passage showing the positional relationship between the traction control throttle valve and the like and the air flow meter, and FIGS. 6 and 7 are FIG. 8 is an explanatory diagram showing the state of the intake flow when the traction control throttle valve is fully opened and fully closed, and FIG. A: main throttle valve, B: traction control throttle valve, C: air flow meter, D: opening detection means, E: correction means.

Claims (1)

[Claims] 1. An internal combustion engine in which a traction control throttle valve whose opening and closing is controlled according to a vehicle running condition is disposed upstream of a main throttle valve whose opening is determined based on an accelerator operation by a driver. An air flow meter arranged between the main throttle valve and the traction control throttle valve, a means for detecting the opening degree of the traction control throttle valve, a flow rate detected by the air flow meter, and an opening degree of the traction control throttle valve. An intake air amount detection device for an internal combustion engine, comprising: