JPH0681910B2 - Engine fuel supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an engine fuel supply device in which the air-fuel ratio is made lean during steady operation of the engine and is controlled to a richer air-fuel ratio during acceleration operation. It is about.

(Prior Art) Conventionally, in the air-fuel ratio control of an engine, in a predetermined operating state in which a required output is low during steady operation or the like, there is known a technique in which an air-fuel ratio is made lean to improve fuel efficiency (for example, , JP-A-57-210137).

Then, depending on the operating condition of the engine as described above,
When the supply air-fuel ratio is controlled by switching between the lean first air-fuel ratio and the richer second air-fuel ratio, the air-fuel ratio fluctuation during acceleration may become large and the acceleration drivability may be impaired. is there.

That is, usually, the acceleration operation is detected from the change in the opening of the throttle valve.However, even if the engine is in the acceleration operation, the acceleration detection mechanism determines that the engine is in the steady state or in the deceleration state, and the supply air is lost. There is a case where the fuel ratio is lean-shifted to hinder smooth acceleration. For example, when the throttle valve is suddenly opened to an acceleration state and then a constant throttle opening is maintained, the engine is in a steady state because there is no change in the throttle opening despite the acceleration state. It is determined that the lean shift is to be made, and thus the air-fuel ratio fluctuates during the acceleration, so that the acceleration performance is hindered.

On the other hand, in regard to the transition to a rich air-fuel ratio with acceleration detection, a technique for maintaining this rich air-fuel ratio for a predetermined period is disclosed, for example, in JP-A-60-60234. ing.

However, in the above technology, while the traveling performance at the time of acceleration can be secured, the period during which the rich air-fuel ratio is maintained does not correspond exactly to the actual acceleration operation state, and it is rich even though it is shifting to steady operation. There is concern about maintaining the air-fuel ratio.

Therefore, the present invention determines the acceleration operation from the change in the throttle opening and also from the change in the intake air amount to promptly detect the transition from the change in the throttle opening to the acceleration operation, while ending the change in the throttle opening. Even so, the air-fuel ratio is accurately enriched in response to the acceleration operation in which the intake air amount increases and changes, but the intake air amount change occurs after the throttle opening change. For,
There is a risk that the acceleration determinations of both will be discontinuous and will be temporarily determined to be steady operation, the air-fuel ratio will be made lean, and good acceleration will not be obtained.

(Object of the invention) In view of the above situation, the present invention leans the air-fuel ratio during steady operation, and determines the acceleration operation from the throttle opening change and intake air amount change to enrich the air-fuel ratio during acceleration operation. Provided is a fuel supply device for an engine, in which acceleration determination is not interrupted temporarily between changes in throttle opening and intake air amount, and fluctuations in air-fuel ratio during acceleration are suppressed to obtain good acceleration performance. The purpose is to do.

(Structure of the Invention) The fuel supply system of the present invention controls the injection pulse to, for example, the injector 3 in the intake passage 2 of the engine 1 as shown in the overall structure diagram for clearly showing the basic structure in FIG. Therefore, the air-fuel ratio control means 4 for adjusting the supply air-fuel ratio is provided, and the air-fuel ratio control means 4 controls the air-fuel ratio of the air-fuel mixture to a relatively lean first air-fuel ratio during steady operation of the engine 1. During the acceleration operation of 1, the second air-fuel ratio richer than the first air-fuel ratio is controlled.

In order to determine the acceleration operation, the first acceleration determination means 6 for determining the acceleration operation based on the change in the throttle opening and the second acceleration for determining the acceleration operation based on the change in the intake air amount based on the signal from the operation state detection means 5. The determination means 8 is provided. Further, the acceleration determination by the first acceleration determination means 6 is to output a signal to the air-fuel ratio control means 4 via the acceleration determination continuation means 7, and the acceleration determination continuation means 7 includes the first acceleration determination means 6 The acceleration determination by the above is continued until the acceleration determination by the second acceleration determining means 8 is performed.

The air-fuel ratio control means 4 receives the acceleration determination signal from the first acceleration determination means 6 and controls the supply air-fuel ratio to shift to the second air-fuel ratio, and the acceleration determination by the second acceleration determination means 8 and the acceleration determination continuation means 7. In response to the signal, the operation based on the second air-fuel ratio is continued, and the acceleration determination continuation means 7 shifts the air-fuel ratio lean between the acceleration determination based on the throttle opening change and the acceleration determination based on the intake air amount change. Is prohibited to maintain operation with a rich air-fuel ratio.

(Effects of the Invention) According to the present invention, when the engine operating state shifts to the acceleration operation, first, the first acceleration determining means makes a quick acceleration determination based on the change in the throttle opening, and the acceleration determination The air-fuel ratio is shifted to the rich second air-fuel ratio to ensure good acceleration at the initial stage of acceleration, and the acceleration determination is also performed by the second acceleration determination means based on the change in the intake air amount.
During acceleration operation in which the intake air amount is increasing even after the change of the throttle opening is completed, it is possible to maintain the operation at the second air-fuel ratio and obtain the enrichment of the air-fuel ratio accurately corresponding to the acceleration operation.

Further, the acceleration judgment by the first acceleration judgment means is continued by the acceleration judgment continuation means until the acceleration judgment by the second acceleration judgment means, and the acceleration judgment by the first acceleration judgment means due to the occurrence of the intake air amount change with a delay. Even if there is a temporary deviation from the acceleration determination by the second acceleration determination means, leaning of the air-fuel ratio during this period is prevented, and the operation is continued at the rich second air-fuel ratio, thereby accelerating. It is possible to prevent the air-fuel ratio from changing to the lean first air-fuel ratio therein, obtain good acceleration performance, and secure drivability.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an overall configuration diagram of an engine equipped with the fuel supply system of the present invention.

Intake passage 2 for supplying intake air to combustion chamber 10 of engine body 1
An injector 3 is disposed in the fuel cell to supply fuel.
In the intake passage 2, an air cleaner 11, an air flow sensor 12 for measuring the intake air amount, and a throttle valve 13 for controlling the intake air amount are sequentially arranged from the upstream side. The combustion chamber
A catalytic converter 15 is provided in an exhaust passage 14 for exhausting exhaust gas from 10.

The amount of fuel injected from the injector 3 is used to adjust the air-fuel ratio supplied to the combustion chamber 10 of the engine body 1. The fuel injection by the injector 3 is controlled by the controller.
It is controlled by the control signal output from 16. The controller 16 includes a throttle opening sensor 17 for detecting the intake air amount signal from the air flow sensor 12 and the opening of the throttle valve 13 in order to detect the operating state of the engine.
From the ignition device 18 (distributor, igniter), the engine speed signal based on the ignition signal from the ignition device 18, the air-fuel ratio detection signal from the O ₂ sensor 19 disposed in the exhaust passage 14 upstream of the catalytic converter 15, and the air cleaner 11. The intake air temperature signal from the installed intake air temperature sensor 20, the water temperature signal from the water temperature sensor 21 that detects the cooling water temperature, and the intake pressure signal from the pressure sensor 22 that detects the intake pressure, respectively, are received to change the engine operating state. Accordingly, the fuel supply amount, that is, the supply air-fuel ratio is controlled. Note that 23 is a battery.

The air-fuel ratio control by the controller 16 controls to a relatively lean first air-fuel ratio in a steady operation state lower than a set load, and based on a signal from the O ₂ sensor 19 during acceleration operation with a high required output. Feedback control is performed to a second air-fuel ratio that is richer than the first air-fuel ratio (for example, the theoretical air-fuel ratio), and further control is performed to an enriched air-fuel ratio in the high load operation region.

Then, it is determined that the engine shifts from the steady operation to the acceleration operation from the fact that the amount of change in the throttle opening is larger than a set value based on the detection signal of the throttle opening sensor 17, and the intake air of the air flow sensor 12 is determined. The determination is made based on the change in the intake air amount that is greater than a predetermined value based on the amount signal.Furthermore, the acceleration judgment based on the change in the throttle opening is maintained for a predetermined time until the acceleration judgment based on the change in the intake air amount is made. To do.

The operation of the controller 16 will be described with reference to the flowchart of FIG. This flow chart shows that the air-fuel ratio is operated at the lean first air-fuel ratio in the lean region of low load and low rotation
The second air-fuel ratio (theoretical air-fuel ratio) which is richer than the first air-fuel ratio in the feedback range of medium-load medium-speed rotation with a larger load than this
When the feedback control is performed in the feedback region, that is, in the second air-fuel ratio, Then, the average value of the correction values is learned, and lean control is performed based on the learned value.

After the start, the controller 16 initializes the system in step S1 and reads signals from various sensors in step S2. Based on this operation state detection, in step S3 the basic injection pulse is mainly determined by the engine speed and the intake air amount.
Calculate T ₀ .

Next, in step S4, it is determined whether or not the operating state is in the feedback condition including the lean region, and if the enrichment condition is NO, the correction coefficient for enrichment is calculated in step S13. If the determination in step S4 is YES, step S
After calculating the feedback correction coefficient in step 5, step S6
In step S12, the feedback control, that is, the O ₂ sensor 19 is determined until the learning is completed.
The air-fuel ratio is controlled to the second air-fuel ratio based on the output of. The learning is completed by determining whether or not the feedback correction value by the feedback control of the air-fuel ratio has been obtained, and when the feedback correction value has been obtained, the learning is completed.

When learning is completed, a learning value is calculated in step S7, it is determined in step S8 whether the operating state is in the lean region, and if NO in the lean region, the feedback control of step S12 is continued. On the other hand, if YES in the lean area,
In step S9, it is determined whether the operating state is the accelerating state, the steady state, or the decelerating state, and when it is in the accelerating state, the feedback control of step S12 is performed. In the steady state, the step
A lean correction coefficient is calculated in S10, and lean control is performed in step S11. On the other hand, when the vehicle is in the deceleration state, the process proceeds to step S14. In this step S14, the final correction coefficient C in each control region is calculated, and based on this, the final injection pulse T is calculated in step S15, and fuel injection is executed.

When the lean region in the steady state is shifted to the acceleration state and the feedback control to the second air-fuel ratio is performed, the acceleration determination based on the change in the throttle opening shifts to the rich second air-fuel ratio and the throttle opening is increased. The acceleration determination based on the change is continued for a predetermined time, and the rich operation based on the second air-fuel ratio is continued while the intake air amount is increasing according to the acceleration determination based on the intake air amount change. It is performed by acceleration judgment.

FIG. 4 shows a theoretical diagram of the acceleration judgment in step S9, and FIG. 5 shows a timing chart thereof. First, when the throttle opening θ exceeds a predetermined value A and the throttle opening change degree Δθ / Δt is a predetermined value B or more, AND1 outputs an acceleration detection signal to OR1, and a signal from a timer is input to this OR1. To be done. The output of OR1 is input to OR2, the acceleration signal DQ based on the change of the intake air amount Qa is input to this OR2, the signal of OR2 is input to AND2, and the deceleration signal (output of 1 during deceleration) is input to this AND2. Is inverted and input, and the output of AND2 is used as the acceleration determination signal in step S9. The above timer operates by the output of "1" from AND1, and obtains the acceleration judgment output of AND2 until the acceleration signal DQ based on the intake air amount Qa is input after the output of AND1 becomes "0". is there.

The acceleration signal DQ based on the intake air amount Qa is a signal that is output when a difference between the change in the intake air amount Qa and its moderation (see FIG. 5) is obtained and the difference is equal to or greater than a predetermined value.

Therefore, as shown in the time chart of FIG. 5, when the throttle opening θ is suddenly opened, the acceleration detection by the change of the throttle opening, that is, the output of AND1 becomes “0” as the change of the throttle opening ends. However, the acceleration determination is continued by the timer, then the acceleration signal DQ by the intake air amount Qa becomes "1" and the acceleration determination is further continued. The operation is continued according to the fuel ratio.

With the above configuration, during acceleration, even if there is no fluctuation in the throttle opening, the acceleration determination is continued to continue the operation at the second air-fuel ratio, and the air-fuel ratio fluctuation to the lean side is blocked to ensure accelerated drivability. Is.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an engine equipped with a fuel supply device for clarifying the configuration of the present invention, FIG. 2 is an overall configuration diagram of a specific example, and FIG. 3 is a flowchart diagram for explaining the operation of a controller. FIG. 4 is a theoretical circuit diagram for acceleration determination, and FIG. 5 is a timing chart diagram for acceleration determination. 1 ... Engine, 2 ... Intake passage 3 ... Injector, 4 ... Air-fuel ratio control means 5 ... Operating state detection means 6 ... First acceleration determination means 7 ... Acceleration determination continuation means 8 ... Second acceleration Judgment means 12 …… Air flow sensor 16 …… Controller 17 …… Throttle opening sensor

Continuation of the front page (56) Reference JP-A 52-6833 (JP, A) JP-A 60-60234 (JP, A) JP-A 58-59328 (JP, A) JP-A 59-176441 (JP , A) JP-A-57-137633 (JP, A)

Claims (1)

[Claims] 1. An air which adjusts an air-fuel ratio of an air-fuel mixture supplied to an engine during a steady operation to a relatively lean first air-fuel ratio and a second air-fuel ratio which is richer than the first air-fuel ratio during an acceleration operation. A fuel supply device for an engine, comprising a fuel ratio control means, comprising: first acceleration determination means for determining acceleration operation based on a change in throttle opening; second acceleration determination means for determining acceleration operation based on a change in intake air amount; An acceleration determination continuation unit that continues the acceleration determination by the first acceleration determination unit until the acceleration determination by the second acceleration determination unit is performed;
The air-fuel ratio control means receives the acceleration determination signal of the first acceleration determination means, controls the transfer of the supply air-fuel ratio to the second air-fuel ratio, and receives the acceleration determination signals of the second acceleration determination means and the acceleration determination continuation means. A fuel supply system for an engine, characterized in that it continues to operate at a second air-fuel ratio.