JP2975206B2 - Flow control valve control method during acceleration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a flow control valve during acceleration by a feedback carburetor mainly applied to an automobile.

[0002]

2. Description of the Related Art Conventionally, in this type of flow control valve control method at the time of acceleration, in a feedback with a catalyst, the opening degree of a throttle valve is reduced as a measure against deterioration of durability and reliability due to overheating of the catalyst and generation of FH. A switch that operates near full open is provided, and as shown in FIG. 4, receiving the signal, stops feedback for adjusting the opening of the flow control valve that opens and closes the air bleed passage of the feedback carburetor. The step corresponding to the opening is instantaneously held at 0 step from the step by the normal feedback control up to that point, so that the air-fuel ratio is made richer than the stoichiometric ratio, and a rise in the catalyst temperature in a high rotation region is suppressed.

[0003] In a high-speed region, as in the air-fuel ratio control device for an internal combustion engine described in Japanese Patent Application Laid-Open No. 57-198353, the feedback control is stopped in place of the previous feedback control and the fixed duty is reduced. It is also known to control the flow rate control valve by using a pressure control valve.

[0004]

However, according to the above-described structure, when the vehicle is accelerated from a steady running at a low rotation speed to be in a high rotation region, the air bleed passage provided with the flow control valve is not provided. When the flow control valve is instantaneously set to 0 step because of its length, the volume of the air bleed passage is purged into the main well of the feedback carburetor, causing a delay in the main system, as shown in part A of FIG. Lean spikes occurred, driving performance deteriorated.

[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 method for controlling the flow rate control valve during acceleration according to the present invention, when controlling the flow rate control valve that opens and closes the air bleed passage of the carburetor to adjust the air-fuel ratio of the air-fuel mixture supplied to the engine, Detects open / closed state and controls flow rate when throttle valve is fully open
In controlling the valve to step 0, the engine speed is detected, and the detected engine speed is adjusted to a predetermined speed.
If the number exceeds the number, the number of steps of the flow control valve is set to the first control.
Move toward zero step at controlled speed to control flow control valve
If the detected engine speed is equal to or lower than the predetermined engine speed, the number of steps of the flow control valve is determined by the first control speed.
The flow shifts toward the 0 step at a slower second control speed to control the flow control valve to reduce the flow rate of air in the air bleed passage.

[0007]

With such a configuration, even when the throttle valve is fully opened, the number of steps of the flow control valve can be reduced only when the engine speed is equal to or lower than a predetermined speed . It switches according to the engine speed and is less than the specified speed
In this case, the speed becomes slower than when the rotation speed exceeds a predetermined rotation speed. <br /> Since the process shifts toward the zero step at a predetermined control speed, the air in the air bleed passage between the flow control valve and the carburetor is discharged .
This will reduce the amount of circulation and therefore the air bleed
The air in the road is not instantaneously purged, and the fuel followability of the main system is improved. Thereby, breathing at the time of acceleration from a low rotation region can be eliminated, and deterioration of drivability is prevented.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a carburetor mounted on an intake manifold of an engine, 2 denotes a mixing chamber, 3 denotes a main jet, 4 denotes a throttle valve, 5 denotes a float chamber, and 6 denotes an air bleed. Is shown. A flow control valve (hereinafter, referred to as ABCV) 8 is provided in an air bleed passage 7 which is a starting end portion of the air bleed 6, and a suction port 8a of the ABCV 8 is opened to the atmosphere. The ABCV 8 has a cusp-shaped valve body 9 which is a valve seat 1.
0, the air flow rate is controlled by changing the opening area of an air passage formed between the valve body 9 and the valve seat 10.
Is attached to the tip of the operating rod 12 of the stepper motor 11. Although not shown, a fuel cut solenoid valve is interposed in each of the main system passage 1a and the slow system passage 1b of the carburetor 1. The solenoid valve used in the following description refers to this.

An O ₂ sensor 15 is provided in the exhaust pipe 14 located upstream of the three-way catalytic converter 13. The O ₂ sensor 15 generates only a low output voltage when the air-fuel ratio of the air-fuel mixture is leaner than the conversion point existing near the stoichiometric air-fuel ratio and the oxygen concentration in the exhaust gas is high. In addition, when the air-fuel ratio of the air-fuel mixture is richer than the conversion point and the oxygen concentration in the exhaust gas is low, a high output voltage can be generated.

Reference numeral 16 denotes a microcomputer system for controlling the ABCV 8, and a central processing unit (C)
PU) 17, storage device 18, input interface 1
9 and an output interface 20. The input interface 19 has a voltage signal a from the O ₂ sensor 15, a signal b from a wide open throttle switch (hereinafter referred to as a WOT switch) 21, and a pulse signal proportional to the engine speed generated at a terminal of the ignition coil 22. c and the like, and an idle feedback control signal d or a normal feedback control signal e is output from the output interface 20 to the ABCV 8. WO
The T switch 21 is a switch that operates when the throttle valve 4 is fully opened and outputs a signal b.

The microcomputer system 16 includes:
Using the voltage signal a output from the O ₂ sensor 15 and the LL signal output from an idle switch (not shown) as main information, the number of steps of the stepper motor 11 for driving the valve element 9 of the ABCV 8 and its step speed (transition speed) ) To select and perform normal feedback (normal F / B) control and idle feedback (ID F / B) control in accordance with the operating state of the engine so that the calculated air-fuel ratio is obtained. Program is built-in. In this embodiment, a program whose outline is shown in FIG. 2 is further incorporated as a program for controlling the ABCV 8 during acceleration when the throttle valve 4 is fully opened.

First, in step 51, it is determined whether or not the WOT switch (WOTSW) 21 is open. If it is not open, the process proceeds to step 61, and if it is open, the process proceeds to step 52. In step 52, the current engine speed E / Grev. There is judged whether or not a predetermined rotational speed N ₁ or less, if it exceeds a predetermined rotational speed N ₁ goes to step 71, if the following process proceeds to step 53. In step 71, the ABCV 8 is changed to the transition speed Tsk as in the related art.
The process instantly shifts to step 0 by ip. The transition speed Tskip is, for example, a speed of transition from 0 to 100 steps in 0.5 seconds. Step 5
In step 3, the ABCV 8 is set to a transition speed T which is a predetermined control speed.
The process proceeds to step 0 by powerZ. The transition speed TpowerZ is preferably equal to the transition speed in the case of normal feedback control. Next, in step 54, it is determined whether or not the ABCV 8 has reached 0 step.
Otherwise, return to step 51.

In the above configuration, as shown in FIG.
In a state where the engine speed is operated at a predetermined rotational speed N ₁ or less, WOT switch 21 is closed, thus it is determined as in step 51 is "No", ABC
V8 is a normal feedback control based on the voltage signal a from the O ₂ sensor 15. Acceleration is performed from such a steady running, and the WOT switch 21 detects that the throttle valve 4 is fully opened (determination of “Yes” in step 51), and the engine speed E / Grev. If is the predetermined rotational speed _{N 1} or less, the control proceeds to steps 51 → Step 52 → Step 53 is reduced toward 0 Step migration rate TpowerZ. Then, the acceleration is continued, the throttle valve 4 is fully opened, and the engine speed E / Grev. If There is a predetermined rotational speed _{N 1} or less, steps 51 5
4 are executed continuously. When the throttle valve 4 is returned during acceleration and the throttle valve 4 is not fully opened, the control proceeds from step 51 to step 61, and normal feedback control is performed from the time when the throttle valve 4 is not fully opened. In the start time points or the way that the acceleration, when the engine speed exceeds a predetermined rotational speed N _1, the process proceeds to control the step 51 → step 52 → step 71,
As before, the ABCV 8 instantaneously shifts to the zero step.

As described above, even if the throttle valve 4 is fully opened, the ABCV 8 is instantaneously shifted to the transition speed T from that point.
rather than shifting to 0 step by skip, when the engine rotational speed at that time is in a predetermined rotational speed N ₁ or less is controlled toward the 0 step by a predetermined transition velocity TpowerZ slower than the migration speed Tskip Speed Therefore, in the air bleed passage 7 between the flow control valve and the carburetor
The air flow rate is reduced. As a result,
Air in the reed passage 7 is instantly purged.
Disappears. When the throttle valve 4 is fully opened,
Jin when the rotation speed is the rotation speed N ₁ or more predetermined, the predetermined
ABCV8 is controlled in 0 steps by the transition speed Tskip
I will. For this reason, it is possible to suppress an excessive rise in temperature of the three-way catalyst 13 when the engine is operated in the high rotation range, and to eliminate a breathing phenomenon that tends to occur when the engine is accelerated from the low rotation range. it can. Therefore, drivability during acceleration is improved.

The present invention is not limited to the embodiment described above.

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

[0018]

As described in detail above, the present invention can be applied to a case where the engine speed at that time is equal to or lower than a predetermined speed even when the throttle valve is fully opened by accelerating from the low speed range. to, the control amount of the flow control valve, the engine
The speed changes according to the rotation speed.
The flow shifts toward the zero step at a predetermined control speed that is slower than when the engine speed exceeds the constant speed, so the amount of air flow in the air bleed passage between the flow control valve and the carburetor is reduced.
As a result, the air in the air bleed passage is not instantaneously purged, thereby improving the fuel followability of the main system, thereby suppressing the occurrence of breathing during acceleration from a low rotation speed region. And drivability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory view showing one 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 embodiment.

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

[Explanation of symbols]

1 ... vaporizer 4 ... throttle valve 7 ... air bleed passage 8 ... flow control valve (ABCV) 15 ... _{O 2} sensor 16 ... microcomputer system 17 ... central processing unit 18 ... memory 19 ... input interface 20 ... output interface 21 ... Wide open throttle switch 22 ... ignition coil

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-191856 (JP, A) JP-A-57-172141 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 7/00-7/28 F02D 41/00-41/40

Claims (1)

(57) [Claims] When controlling a flow control valve that opens and closes an air bleed passage of a carburetor in order to adjust an air-fuel ratio of an air-fuel mixture supplied to an engine, an open / close state of a throttle valve is detected and the throttle valve is fully opened. Flow control in case
In controlling the valve to step 0, the engine speed is detected, and the detected engine speed is adjusted to a predetermined speed.
If the number exceeds the number, the number of steps of the flow control valve is set to the first control.
Move toward zero step at controlled speed to control flow control valve
If the detected engine speed is equal to or lower than the predetermined engine speed, the number of steps of the flow control valve is determined by the first control speed.
A method of controlling a flow control valve at the time of acceleration, characterized in that the flow shifts toward 0 step at a second control speed that is slower to control the flow control valve to reduce the flow rate of air in the air bleed passage.