JP2631587B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine that uses different types of fuel, for example, gasoline and alcohol, by switching or mixing them.

2. Description of the Related Art In an internal combustion engine which can be used by switching or mixing gasoline and alcohol, an alcohol sensor for detecting an alcohol concentration is provided, and a fuel supply amount is corrected based on the detected value of the alcohol concentration. As a device for controlling the air-fuel ratio, there is a device as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-98540. Note that the fuel supply amount is feedback-controlled so that the air-fuel ratio detected by the O ₂ sensor under predetermined operating conditions approaches the target air-fuel ratio (stoichiometric air-fuel ratio). On the other hand, in the air-fuel ratio control device of the electronic control type, the deviation of the air-fuel ratio from the target value in the non-feedback control region of the air-fuel ratio or the stoichiometric air-fuel ratio during the transient operation in which the operation region under feedback control moves. In order to suppress the deviation, it is becoming common to perform a learning control by setting a learning value so that the average value of the air-fuel ratio feedback correction value approaches a reference value under predetermined steady-state operating conditions during the air-fuel ratio feedback control. .

However, when the above-mentioned learning control is performed, an engine using only one kind of fuel, for example, gasoline, is classified according to the engine speed and the engine load (for example, the basic fuel supply amount). Although good learning control is performed by setting a learning value for each region, in an engine that uses a mixture of different types of fuel, the detection accuracy of the concentration sensor varies greatly, so even in the same operation region, If the used fuel concentration is different, the learning value greatly differs due to the difference in the characteristics, and the learning may sometimes impair the air-fuel ratio control performance. The present invention has been made in view of such a conventional situation, and a fuel supply control of an internal combustion engine in which appropriate learning is performed in accordance with a used fuel concentration, thereby obtaining good air-fuel ratio control performance. It is intended to provide a device.

According to the present invention, there is provided:
As shown in FIG. 1, the invention according to claim 1 is an internal combustion engine which can be used by switching or mixing different kinds of fuels, according to a reference fuel concentration detected by fuel concentration detecting means. Concentration correction means for correcting the fuel supply amount based on the corrected concentration correction value, and air-fuel ratio feedback correction means for correcting the air-fuel ratio detected by the air-fuel ratio detection means under predetermined operating conditions with a feedback correction value so as to approach the target air-fuel ratio. And a fuel supply means for supplying at least an amount of fuel corrected by the concentration correction value and the feedback correction value. Calculates the average value of the feedback correction values by the feedback control means for a predetermined period after entering the plurality of density areas. Setting a learning value for correcting the density correction value by the density correction means based on the average value; and providing a density correction value learning means for storing the learning value in the density area of the storage means. The fuel supply amount is corrected using the concentration correction value corrected by the learning value stored in the concentration region to be adjusted. In the present invention, claim 2
In the invention according to the first aspect, the density correction value learning means has the following configuration in the same configuration as the first aspect. That is, the concentration correction value learning unit calculates the average value of the feedback correction values by the feedback control unit for a predetermined period after entering the concentration region divided into a plurality of regions according to the reference fuel concentration detected by the concentration detection unit. Setting a learning value for correcting the density correction value by the density correction means based on a deviation amount between the average value in the density area and the average value calculated in the previous different density area; and storing the learning value in the storage means. It is stored in the density area.

According to the first aspect of the invention, the concentration correction value learning means performs learning based on the average value of the feedback correction values for each concentration region of the used fuel, and uses the concentration correction value corrected by the learning value. The corrected fuel amount is supplied from the fuel supply means, so that good air-fuel ratio control is performed even when the used fuel concentration changes. In this case, the variation with respect to the change of the operation range is not learned, but the variation due to the fuel used has a greater effect. Therefore, by performing the learning, the air-fuel ratio control performance can be sufficiently improved. Therefore, when a memory map of the learning value according to the operation area (rotational speed, load) is provided for each fuel concentration, the air-fuel ratio control can be performed with the smallest possible amount of storage, considering that the storage amount is enormously increased. The advantage that performance can be improved is great. In the invention according to claim 2, the learning based on the average value of the feedback correction values is performed by the concentration correction value learning means for each of the concentration regions of the used fuel in the same manner as described above. Since the density correction value is corrected based on the deviation from the average value in the above, learning control can be performed in which the learning amount due to the density change is more strongly reflected, and the air-fuel ratio control performance can be increased without increasing the storage amount as described above. Can be improved as much as possible.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of one embodiment, an internal combustion engine 1 which can be used by switching or mixing different kinds of fuel is provided with an air flow meter 2 for detecting an intake air flow rate in an intake passage thereof, and a fuel supply means. And a crank angle sensor 4 mounted on a crankshaft or a distributor and outputting a pulse signal for each unit crank angle of the engine 1 is provided.
Further, the exhaust passage 5 is provided with an O ₂ sensor 6 as an air-fuel ratio detecting means for detecting the oxygen concentration in the exhaust gas to detect the air-fuel ratio. The fuel supply pipe for supplying fuel to the engine 1 has an alcohol sensor 7 as fuel concentration detecting means for detecting the concentration of alcohol as a reference fuel in a mixed fuel of alcohol and gasoline flowing through the fuel supply pipe. A fuel temperature sensor 8 for detecting a temperature is provided. Detection signals from these sensors are input to a control unit 9 having a built-in microcomputer, and the control unit 9 determines the fuel injection amount (fuel supply amount) based on these detection results and a learning value for an alcohol concentration value described later. Calculates and outputs a fuel injection signal corresponding to the calculated value to the fuel injector 3, whereby the fuel injector 3 injects and supplies an amount of fuel corresponding to the calculated value. Further, under predetermined operating conditions, fuel supply control is performed so that the air-fuel ratio detected by the O ₂ sensor 6 approaches the target air-fuel ratio (the stoichiometric air-fuel ratio). Next, a fuel supply control routine by the control unit 9 will be described with reference to the flowcharts of FIGS. FIG. 3 shows a fuel injection amount setting routine, which is performed at predetermined intervals (for example, every 10 ms). In step (denoted as S in the figure) 1, the intake air flow rate Q detected by the air flow meter 2 and the crank angle sensor 4
Based on the engine speed N calculated on the basis of the signal from the basic fuel injection quantity T _P corresponding to the intake air amount per unit rotation is calculated by the following equation. T _P = K × Q / N (K is a constant) In step 2, various correction coefficients COEF are set based on the cooling water temperature Tw and the like detected by the water temperature sensor 17. In step 3, a feedback correction coefficient α set by a later-described feedback correction coefficient setting routine is read. In step 4, a voltage correction amount T _S is set based on the battery voltage value. This is for correcting a change in the injection flow rate of the fuel injection valve 3 due to the battery voltage fluctuation. In step 5, based on the alcohol concentration detected by the alcohol sensor 7, the basic value ALC of the concentration correction value stored in the ROM map of the control unit 9 and the corresponding concentration area stored in the RAM map are stored. The learning value ALCLRN is read.
Note that the map of the RAM corresponds to a storage unit. In step 6, the final fuel injection quantity (fuel supply quantity) T _I is calculated according to the following equation. T _I = T _P × COEF × α × ALC × ALCLRN + T _S Here, when setting the fuel injection amount T _I , the concentration correction value AL
The correction by C and the correction by the feedback correction value α are performed. Therefore, the function of this step 6 has both functions of the concentration correction means and the air-fuel ratio feedback correction means. In step 7, the calculated fuel injection valve T _I
Is set in the output register. Accordingly, at a predetermined fuel injection timing synchronized with the engine rotation, a drive pulse signal having a pulse width of the calculated fuel injection amount T _I is given to the fuel injection valve 15 to perform fuel injection. FIG.
Indicates a learning routine for the density correction value. This routine corresponds to the density correction value learning means according to the first aspect of the present invention. In step 11, the concentration area of the RAM corresponding to the alcohol concentration detected by the alcohol sensor 7 is
It detects whether it is the same as the previous time. If the areas are different, the routine proceeds to step 12, where the value of the counter C for measuring the number of reversals of the detection value of the O ₂ sensor 6 is reset to 0, and this routine is terminated. If it is determined in step 11 that the area is the same, the process proceeds to step 13 and the O ₂ sensor 6
It is detected whether or not the detection value of is inverted. If it is determined that the inversion has not occurred, this routine ends. If it is determined that the inversion has occurred, the process proceeds to step 14, where the value of the counter C is incremented.
To read the current air-fuel ratio feedback correction value α. The feedback correction value α is determined by changing the output of the O ₂ sensor 6 from lean (rich) to rich in another routine.
This is set by the so-called proportional integration control in which the predetermined proportional component P is increased (decreased) when the ratio is inverted to (lean), and thereafter increased (decreased) by the integral component I. Briefly,
The integral may be set by the integral control of only the integral, or for higher accuracy, the differential may be added and set by the proportional integral differential control. In step 16, it is determined whether or not the value of the counter C has reached a predetermined value C ₀ (even number). If the predetermined value C ₀ has not been reached, this routine is terminated.
Average value α _M of feedback correction value α read ₀ times
Is calculated. In step 18, by the average value alpha _M,
The learning value ALCLRN stored in the current alcohol concentration area of the RAM is rewritten. That is, in this embodiment the average value alpha _M of the feedback correction value alpha functions as a learning value for correcting the density correction value. In step 19, the count value of the counter C is reset to zero. With this configuration, the concentration correction value is corrected for each concentration region based on the learning value obtained by learning the deviation of the air-fuel ratio in the steady state. Can be effectively eliminated, and stable air-fuel ratio control is performed. In addition, as the map for storing the learning value, it is sufficient to prepare one two-dimensional map for the alcohol concentration, and the storage amount is sufficiently small. Since the variation in the detected alcohol concentration is significantly affected by the fuel temperature in addition to the variation in the characteristics of the alcohol sensor 7 itself, learning is performed for each area divided by the alcohol concentration and the fuel temperature detected by the fuel temperature sensor. If the learning value is stored for each corresponding area of the three-dimensional map, the air-fuel ratio control accuracy can be further improved. FIG. 5 shows a routine for learning a density correction value in the second embodiment (an embodiment of the invention according to claim 2). FIG. 4 shows the fuel injection amount setting routine.
Therefore, the description is omitted. Steps 21, 23 to 27 are the same as steps 11, 13 to 16 in FIG. In step 28, the deviation amount [Delta] [alpha] _M of the average value alpha _M-1 of the average value alpha _M and alcohol concentration regions having different previous feedback correction value in the current alcohol concentration region calculated in step 27
Is calculated. In step 29, the learning value ALCLRN the using the deviation amount [Delta] [alpha] _M was corrected by the following equation, the learning value stored in the region defined by the detected fuel temperature by the current alcohol concentration and the fuel temperature sensor 8 of the RAM ALCL
Rewrite RN. ALCLRN ← ALCLRN + Δα _M / n (n> 1) In step 30, the count value of the counter C is reset to zero. If the density region has changed in the determination of step 21, the process proceeds to step 22 to reset the count value of the counter C to 0, and for the calculation in step 28, the current average value α _{M is changed} to α _M−1 And set it again. In this embodiment, different for learning based on the deviation amount [Delta] [alpha] _M of the average value of the air-fuel ratio feedback correction value between the alcohol concentration region is performed, it can effectively eliminate variations of the air-fuel ratio due to the alcohol concentration, the air The fuel ratio control is improved.

As described above, according to the present invention, since the concentration correction value is learned and stored for each concentration region of the reference fuel, the deviation of the air-fuel ratio due to the variation of the concentration detection value can be reduced. Thus, stable air-fuel ratio control accuracy can be obtained over the entire concentration range. Further, by performing learning based on the deviation of the average value of the air-fuel ratio feedback correction value between the concentration ranges, the learning is performed by more accurately extracting the variation in the air-fuel ratio due to the influence of the reference fuel concentration. Thus, high-precision air-fuel ratio control that more effectively eliminates variations in the air-fuel ratio during the period can be performed.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a fuel injection amount setting routine of the embodiment.

FIG. 4 is a flowchart showing a density correction learning routine of the embodiment.

FIG. 5 is a flowchart illustrating a density correction learning routine according to another embodiment.

[Explanation of symbols]

1 engine 3 fuel injection valve 6 O ₂ sensor 7 alcohol sensor 9 Control Unit

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication F02D 45/00 340 F02D 45/00 340C

Claims (2)

(57) [Claims] An internal combustion engine capable of switching or mixing different types of fuels, wherein a fuel supply amount is determined by a concentration correction value corresponding to a reference fuel concentration detected by fuel concentration detecting means. Concentration correction means for correcting, and air-fuel ratio feedback correction means for correcting the fuel supply amount by a feedback correction value so that the air-fuel ratio detected by the air-fuel ratio detection means under predetermined operating conditions approaches the target air-fuel ratio; A fuel supply unit that supplies an amount of fuel corrected by the correction value and the feedback correction value, wherein the fuel supply control unit is divided into a plurality of fuel cells according to the reference fuel concentration detected by the concentration detection unit. The average value of the feedback correction values by the feedback control means for a predetermined period after entering the density region is calculated, and the average value is calculated. Then, a learning value for correcting a density correction value by the density correction means is set, and a density correction value learning means for storing the learning value in the density area of the storage means is provided, and stored in a corresponding density area of the storage means. A fuel supply control device for an internal combustion engine, wherein a fuel supply amount is corrected by using a concentration correction value corrected by a learned value. 2. An internal combustion engine which can be used by switching or mixing different kinds of fuels, wherein a fuel supply amount is determined by a concentration correction value corresponding to a reference fuel concentration detected by fuel concentration detecting means. Concentration correction means for correcting, air-fuel ratio feedback correction means for correcting the air-fuel ratio detected by the air-fuel ratio detection means under predetermined operating conditions with a feedback correction value so as to approach the target air-fuel ratio, and at least the concentration correction value and feedback Fuel supply means for supplying an amount of fuel corrected by the correction value, the fuel supply control device comprising: a fuel supply control device configured to enter a concentration area divided into a plurality of areas according to the reference fuel concentration detected by the concentration detection means; The average value of the feedback correction values by the feedback control means for a predetermined period after the calculation is calculated, and the average value of A learning value for correcting the density correction value by the density correction means is set based on the deviation amount between the value and the average value calculated in the previous different density area, and the learning value is stored in the density area of the storage means. Fuel supply for an internal combustion engine, wherein a concentration correction value learning means is provided, and a fuel supply amount is corrected using a concentration correction value corrected by a learning value stored in a corresponding concentration area of the storage means. Control device.