JPH0522058B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel control device for an engine, and particularly to a device for appropriately controlling fuel during acceleration.

[Prior art] Conventionally, as seen in Japanese Patent Publication No. 47-38665, in addition to basic fuel control that controls the fuel injection amount according to intake pipe negative pressure, engine speed, etc.
A control device that increases the amount of fuel during acceleration is known. This device aims to improve acceleration performance, and since there is an inherent tendency for a fuel shortage to occur due to a sudden increase in the amount of intake air during acceleration, it is designed to supplement fuel in this case. It is.

[Problem to be solved by the invention]

However, with this conventional device, the fuel increase value during acceleration is simply determined experimentally in advance, so if there are variations in performance between engines or changes over time, the above fuel increase value may not necessarily be the appropriate value. In some cases, the increase value was too large, resulting in poor fuel efficiency, or the increase value was too small, resulting in insufficient acceleration.

The purpose of the present invention is to eliminate the drawbacks of such conventional devices, and to improve the fuel increase value during acceleration so that it can be maintained at an appropriate level even when there are variations in performance between engines and changes over time. It is an object of the present invention to provide a fuel control device for an engine that can correct the fuel increase value through learning and, in particular, can appropriately correct the fuel increase value even in various operating ranges.

[Means to solve the problem]

As shown in the overall configuration diagram of Fig. 1, the engine 1
A control unit 21 that controls the fuel injection valve 5 (another device includes a carburetor) installed in the intake passage 2 of the fuel injection valve 21 includes a fuel injection valve that increases the amount of fuel in accordance with a detection signal from an acceleration detection unit 23. A volume increasing means 22 is included. In order to optimize the fuel increase value during acceleration by the increase means 22, a first storage means 24 for storing the fuel increase value, and a first air-fuel ratio fluctuation detection means 25 for detecting a drop in the air-fuel ratio only during acceleration. , a second air-fuel ratio fluctuation detection means 26 for detecting air-fuel ratio droop only during steady state; and a preset air-fuel ratio droop detected by receiving the output of the second air-fuel ratio fluctuation detecting means 26. A second storage means 27 stores data for each operating region, and receives the outputs of the first air-fuel ratio fluctuation detection means 25 and the second storage means 27, and stores information on the air-fuel ratio only during acceleration and in the operating region where acceleration was performed. Comparing means 28 for comparing the correspondingly stored air-fuel ratio sloping only during steady state, and receiving the output of this comparing means 28, the air-fuel ratio sagging only during acceleration is compared with the air-fuel ratio sloping only during steady state. A rewriting means 29 is provided for rewriting and correcting the fuel increase value stored in the first storage means 24 so as to reduce the droop in the air-fuel ratio during acceleration when a large condition is detected. The first and second air-fuel ratio fluctuation detection means 25 and 26 check the fuel lean time determined based on the detection signal from the O ₂ sensor during acceleration and steady state, or detect engine vibration, etc. Accordingly, a drop in the air-fuel ratio is detected.

[Effect]

According to the above configuration, when accelerating, the air-fuel ratio drop only during acceleration is compared with the air-fuel ratio drop during steady state in the same operating region as the operating region at that time, thereby correctly determining the steady state in that operating region. The size of the drop in the air-fuel ratio during acceleration compared to normal conditions was investigated.
Based on this, the fuel increase value is corrected with high accuracy.

〔Example〕

In FIG. 2, 1 is an engine, 2 is an intake passage, and 3 is an exhaust passage. The intake passage 2 is provided with a throttle valve 4 and a fuel injection valve 5 downstream thereof. This fuel injection valve 5
is controlled by a control unit 20 using a microcomputer.

11 is an air flow meter that detects the amount of intake air;
12 is a pressure sensor that detects the pressure in the intake manifold, 13 is an engine speed sensor, 14 is a throttle opening sensor, and 15 is a sensor that detects whether the mixture is rich or lean based on the amount of O ₂ in the exhaust gas.
It is an _O2 sensor. These detection signals are input to the control unit 20.

The control unit 20 includes a microprocessor (not shown), a memory, an interface, etc., and stores a ROM of fuel injection amount corresponding to the engine speed and intake manifold pressure in the memory.
A fuel reference control value corresponding to the operating condition can be determined from this ROM map. Fuel control during steady operation is performed by correcting the above fuel reference control value through feedback control according to the signal from the O ₂ sensor 15, reducing the amount of fuel when the engine is in a rich state, and increasing the amount of fuel when the engine is in a lean state. Therefore, the rich state and lean state are repeated at appropriate intervals. Furthermore, the memory stores a correction system that determines the fuel increase value during acceleration in association with the throttle opening change rate that indicates the degree of acceleration and the fuel injection pulse width that indicates the operating state. Lean time (duration of lean state) only during steady operation is set for each operating region in advance, in association with the value map (corresponding to the first storage means), engine speed and load (intake manifold pressure). A lean time map (corresponding to second storage means) to be stored is included. The stored values of these maps can be rewritten. Further, the acceleration driving state is detected by examining a change in the detection signal from the throttle opening sensor 14.

Lean time is detected during steady operation as a drop in the air-fuel ratio only during steady state, and the lean time detected during steady operation is stored in the lean time map for each operating region. Also, based on the above acceleration detection, when accelerating, if the lean condition is present, the fuel injection amount is increased according to the correction coefficient read from the map, and on the other hand, the lean time at this time is adjusted to the operating region where the acceleration was performed. It is compared with the corresponding lean time during steady operation (value read from the lean time map), and the correction coefficient is rewritten according to the difference. In this way,
Each means shown in the above-mentioned overall configuration diagram is substantially included in the control unit 20.

Flowcharts for controlling this device are shown in FIGS. 3 to 6.

In the main routine shown in FIG. 3, after initialization in step 31, the manifold pressure detection signal from the pressure sensor 12 is A/D converted in step 32. Next, after passing through the subroutine () for determining acceleration and the subroutine () for rewriting and correcting the correction coefficient for acceleration, the process returns to step 32 and the flow is repeated.

In the subroutine () for acceleration determination, as shown in FIG. 4, in step 33, the signal from the throttle opening sensor 14 is A/D converted, and in step 34, the signals from the current detection and the previous detection are converted. The throttle opening difference (θ=θn−θo _-1 ) is determined.
Next, this throttle opening difference θ is compared with a predetermined reference value θ ₁ , and depending on whether θ≧θ ₁ , an accelerating operating state and a steady operating state are distinguished (step
35), if it is in an accelerated driving state, the discrimination value A is set to 1,
If the operating state is steady, the discrimination value A is set to 0 and stored in the register (steps 36 and 37).

In the subroutine () for rewriting and correcting the correction coefficient for acceleration, as shown in FIG. 5, it is determined in step 38 whether or not the operation is steady (A=0). When steady operation is being performed, it is determined in step 39 whether the lean state has changed to the rich state based on the signal from the O ₂ sensor 15, and when the state has changed to the rich state, the operating state at that time is determined. The lean time t at is detected, and the stored value corresponding to the relevant operating region in the lean time map is rewritten (step 40).

If accelerating operation is being performed, it is determined in step 41 whether the lean state has changed to the rich state, and if there has been no change, it is further determined whether the lean state has been reached (step 42). If so, the measured lean time value K is increased to K+1 (step 43). In other words, the lean time during acceleration is detected by increasing the lean time measurement value K at regular intervals from the lean state until the rich state. When the state changes to a rich state, the lean time K indicating the drooping of the air-fuel ratio only during acceleration determined at that time, and the air-fuel ratio only during steady state stored corresponding to the operating region in which acceleration was performed. The lean time t obtained during steady operation is compared with the lean time t obtained from the lean time map, and it is determined whether K≧t (step 44).
If K≧t, the correction coefficient learning value C _A in the correction coefficient learning value map corresponding to this condition is
The value is rewritten and stored by adding mΔC _A (step 45). Here, m is a value corresponding to the difference (K-t) between the two lean times, and ΔC _A is a set value. On the other hand, if K<t, the correction coefficient learning value
C _A is subtracted by ΔC _A , and if this subtracted value is larger than 1, the correction coefficient learning value in the map is rewritten to this value and stored, and if the subtracted value is smaller than 1, C _A is stored as 1 (steps 47-49). The reason why C _A is set to 1 in step 48 is to prevent the fuel from being reduced during acceleration. After rewriting in this way, the lean time measurement value K is set to 0 (step
50).

FIG. 6 shows an interrupt handling routine. This routine starts at, for example, 60° BTDC, first, in step 51, the engine speed is calculated by periodic measurement, and in step 52, the operating state is detected from the engine speed and manifold pressure. . Next, in step 53, a fuel reference control value Ti according to the operating condition is calculated from the ROM map of the fuel injection amount, and further, in step 54, feedback correction is performed based on the signal from the O ₂ sensor 15, and during steady operation, An appropriate fuel control value Ti' is determined. after that,
In step 55, it is determined whether or not acceleration operation (A=1) is being performed, and if it is during acceleration operation, it is further determined whether or not it is in a lean state (step 56), and if it is in a lean state, a correction coefficient learning value map is The fuel control value Ti' is multiplied by the learning value C _A corresponding to the rate of change in the throttle opening degree determined from the above, and the increased fuel injection amount T is calculated (step 57). In this case, when the predetermined injection timing is reached, with the increased fuel injection amount T, or with the fuel control value Ti′ when the operation is steady or when the lean state is not present even during acceleration. Fuel injection takes place (steps 58, 59).

By performing control according to the above flowchart, the amount of fuel is increased when the fuel is in a lean state during acceleration, and even if this increased amount (correction coefficient learning value C _A ) is initially inappropriate, the above steps are performed. It will be rewritten and corrected in 45 and 46. In this case, the lean time only during steady operation is stored in the lean time map for each operating region, and when accelerating, the lean time only during acceleration is compared with the lean time only during steady state operation in the same operating region. , the difference in air-fuel ratio deterioration between acceleration and steady state is correctly investigated, and based on this, the above-mentioned correction is performed with high precision. After this correction, the corrected increase value will be given the next time acceleration is performed under the same conditions. After this operation is repeated to a certain extent, the learned value stored in the map
C _A is corrected with high precision, and fuel that is increased by the appropriate amount is immediately supplied in response to acceleration operations.

In addition to the above-mentioned embodiments, as a means for rewriting and correcting the fuel increase value according to the drop in the air-fuel ratio, for example, it is possible to use a method that uses vibrations during acceleration and vibrations during steady state stored corresponding to the operating range. The acceleration transition may be checked by comparison, and the correction coefficient learning value C _A may be rewritten and corrected accordingly. Further, the amount of fuel during acceleration may be increased by increasing the pulse width of the regular injection pulse, or by outputting a temporary injection pulse. Furthermore, the fuel supply is not limited to a fuel injection valve, and may be supplied by a carburetor.

[Effects of the Invention] As described above, the present invention stores the fuel increase value during acceleration, and increases the fuel amount based on the comparison between the air-fuel ratio drop only during acceleration and the air-fuel ratio drop only during steady state. Since the fuel increase value is rewritten and corrected, even if there are variations in performance between engines or changes over time, the fuel increase value can be optimized by learning.
It is possible to reliably prevent a decrease in output during acceleration and a deterioration in fuel efficiency. In particular, the air-fuel ratio slump detected during steady operation is stored for each operating region, and the air-fuel ratio slump only during acceleration is stored corresponding to the operating region in which acceleration occurs. Since the fuel increase value is corrected based on the comparison with the air-fuel ratio, the above correction can be made with high accuracy in various operating ranges.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the apparatus of the present invention, FIG. 2 is a schematic diagram showing an embodiment, and FIGS. 3 to 6 are flowcharts. DESCRIPTION OF SYMBOLS 1... Engine, 5... Fuel injection valve, 22... Fuel increase means, 23... Acceleration detection means, 24... First storage means, 25... First air-fuel ratio fluctuation detection means, 26... Second
Air-fuel ratio fluctuation detection means, 27...second storage means, 28
... Comparison means, 29... Rewriting means.

Claims (1)

[Claims] 1. A fuel control device for an engine comprising a fuel increasing means for increasing the amount of fuel in response to a detection signal from an acceleration detecting means when the engine accelerates, comprising: a first storage means for storing a fuel increase value by the fuel increasing means; The first to detect the air-fuel ratio drop only when
an air-fuel ratio fluctuation detection means, a second air-fuel ratio fluctuation detection means for detecting air-fuel ratio droop only during steady state, and an air-fuel ratio droop detected only during steady state in response to the output of the second air-fuel ratio fluctuation detection means. a second storage means for storing the following information for each preset operating region; and a second storage means that receives the outputs of the first air-fuel ratio fluctuation detection means and the second storage means to store the air-fuel ratio only during acceleration and the operating region in which acceleration was performed. a comparison means for comparing the air-fuel ratio difference only during steady state stored correspondingly to the air-fuel ratio difference only during steady state; and rewriting means for rewriting and correcting the fuel increase value stored in the first storage means so as to reduce the droop in the air-fuel ratio during acceleration when a large state is detected. Device.