JP2627826B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine in which a fuel supply amount is corrected and set according to a fuel temperature.

[0002]

2. Description of the Related Art In an electronically controlled fuel supply control device, an air-fuel ratio of an air-fuel mixture is controlled by setting a fuel supply amount in accordance with an engine operating state. The feedback control is performed so that the air-fuel ratio approaches the target air-fuel ratio on the basis of the detected value of.

On the other hand, in an internal combustion engine which can be used by switching or mixing gasoline and alcohol, an alcohol sensor for detecting the alcohol concentration is provided, and the fuel supply amount is corrected based on the detected value of the alcohol concentration. To control the air-fuel ratio (see JP-A-56-98540).
. In addition, in order to suppress the deviation of the air-fuel ratio from the target value in the non-feedback control region of the air-fuel ratio or the deviation from the stoichiometric air-fuel ratio during the transient operation in which the operation region under feedback control moves, a predetermined value is set during the air-fuel ratio feedback control. It has become common to perform 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 the steady-state operating conditions described above.

[0004]

In the learning control of the air-fuel ratio as described above, since the control of the fuel supply amount is performed by the injection pulse width, it is controlled by the volume flow rate. Varies depending on the fuel temperature, so that the mass fuel amount for the same injection pulse width differs depending on the fuel temperature. Although the required fuel amount is constantly supplied by performing the air-fuel ratio feedback control,
The learning value varies for each fuel temperature, and affects the control performance.

[0005] Further, as described above, when the air-fuel ratio is controlled by the alcohol sensor in accordance with the alcohol concentration,
Since the detection accuracy of the alcohol sensor varies greatly depending on the fuel temperature, the variation of the learning value also increases.
The air-fuel ratio control performance was sometimes impaired by learning. The present invention has been made in view of such a conventional situation, and a fuel supply control device for an internal combustion engine in which appropriate learning is performed in accordance with a fuel temperature, so that good air-fuel ratio control performance can be obtained. The purpose is to provide.

[0006]

According to the present invention, there is provided:
As shown in FIG. 1, the invention according to claim 1 includes a basic fuel supply amount setting unit that sets a basic fuel supply amount according to an engine operating state, and an air-fuel ratio detected by an air-fuel ratio detection unit under predetermined operating conditions. A fuel supply amount correction unit that corrects a fuel supply amount with a feedback correction value so as to approach the target air-fuel ratio, and a fuel supply unit that supplies an amount of fuel corrected by the feedback correction value. In the control device, a fuel temperature detecting means for detecting a temperature of the fuel, and a fuel temperature detected by the air-fuel ratio detecting means after entering a temperature region divided into a plurality of areas according to the fuel temperature detected by the fuel temperature detecting means. The average value of the feedback correction values by the feedback control means until the magnitude relationship between the air-fuel ratio and the target air-fuel ratio is inverted a predetermined number of times is calculated. Then, a learning value for correcting the basic fuel supply amount is set based on the average value, and a temperature learning unit for storing the learning value in the temperature region of the storage unit is provided. The fuel supply amount is set using the basic fuel supply amount corrected with the stored learning value.

In the invention according to a second aspect of the present invention, the temperature correction value learning means has the following configuration in the same configuration as the first aspect of the invention. That is,
The temperature learning means determines a magnitude relationship between an air-fuel ratio detected by the air-fuel ratio detection means and a target air-fuel ratio after entering into a plurality of temperature ranges according to the fuel temperature detected by the fuel temperature detection means. An average value of the feedback correction values by the feedback control means until the number of times of inversion is calculated, and the basic fuel supply is performed based on a deviation amount between the average value in the temperature region and the average value calculated in the previous different temperature region. A learning value for correcting the amount is set, and the learning value is stored in the temperature region of the storage unit.

[0008]

According to the first aspect of the present invention, the learning based on the average value of the feedback correction value is performed by the temperature learning means for each fuel temperature range, and the temperature is set using the basic fuel supply amount corrected by the learning value. Since the set amount of fuel is supplied from the fuel supply means, good air-fuel ratio control is performed even if the fuel temperature changes. In this case, the variation with respect to the change of the operating region is not learned, but the variation due to the fuel temperature has a greater effect. Therefore, by performing the learning, the air-fuel ratio control performance can be sufficiently improved. Therefore, when a storage map of the learning values according to the operation area (rotational speed, load) is provided for each fuel temperature, considering the enormous storage amount, the air-fuel ratio control can be performed with the smallest possible storage amount. The advantage that performance can be improved is great.

According to the second aspect of the present invention, the learning based on the average value of the feedback correction value is performed by the temperature learning means for each fuel temperature region in the same manner as described above. Since the learning value is set based on the deviation from the average value, learning control can be performed in which the learning amount due to the temperature change is more strongly reflected, and the air-fuel ratio control performance can be improved without increasing the storage amount as described above. It can be improved as much as possible.

[0010]

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 an oxygen concentration in the exhaust gas to detect an air-fuel ratio, and a water temperature sensor for detecting a cooling water temperature is provided on a water jacket of the engine 1. Ten are provided.

The fuel supply pipe for supplying fuel to the engine 1 has an alcohol sensor 7 for detecting the concentration of alcohol as a reference fuel in a mixed fuel of alcohol and gasoline flowing through the fuel supply pipe, and a fuel temperature detection. A fuel temperature sensor 8 is provided as a fuel temperature detecting means. 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 amount per unit rotation is calculated based on the intake air flow rate Q detected by the air flow meter 2 and the engine speed N calculated based on the signal from the crank angle sensor 4. the basic fuel injection quantity T _P corresponding to operation by the following equation. The function of step 1 constitutes basic fuel supply amount setting means.

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 detected by the water temperature sensor 10. 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 value 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, the concentration correction value ALC stored in the map of the ROM built in the control unit 9 is read based on the alcohol concentration detected by the alcohol sensor 7, and based on the fuel temperature detected by the fuel temperature sensor 8. The learning value FTMLRN of the corresponding temperature region stored in the map of the RAM is read.
Note that the map of the RAM corresponds to a storage unit.

[0015] 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 × FTMLRN + T _S Here, when setting the fuel injection amount T _I , a correction is made with the feedback correction value α. Therefore, the function of this step 6 is to perform the air-fuel ratio feedback correction. Configure means.

In step 7, the calculated fuel injection valve T
Set _I in the output register. Thereby, when the predetermined fuel injection timing synchronized with the engine rotation is reached,
Drive pulse signal having a pulse width of the calculated fuel injection amount T _I is is given to the fuel injection valve 15 fuel injection is performed. FIG. 5 shows a temperature learning routine. This routine corresponds to the temperature learning means of the first aspect.

In step 11, it is detected whether or not the temperature area of the RAM corresponding to the fuel temperature detected by the fuel temperature sensor 8 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 areas are the same, the process proceeds to step 13, where it is detected whether or not the detection value of the O ₂ sensor 6 has been 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, and after the value of the counter C is incremented, the process proceeds to step 15 and the current The air-fuel ratio feedback correction value α is read. The feedback correction value α is increased (decreased) by a predetermined proportional amount P when the output of the O ₂ sensor 6 is inverted from lean (rich) to rich (lean) in another routine, and thereafter increases by an integral amount I. (Decrease) is set by so-called proportional integration control. For simplicity, the integral may be set by the integral control of only the integral. 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 ended. If it has reached, the routine proceeds to step 17, where the average value α _M of the feedback correction values α read C ₀ times is calculated.

In step 18, according to the average value α _M ,
The learning value F stored in the current fuel temperature area of the RAM
Rewrite TMLRN. That is, in this embodiment the average value alpha _M of the feedback correction value alpha functions as a learning value for correcting the basic fuel supply quantity. In step 19, the count value of the counter C is reset to zero.

With this configuration, the basic fuel supply amount is corrected for each temperature range based on the learned value obtained by learning the deviation of the air-fuel ratio in a steady state. Thus, fluctuations in the air-fuel ratio due to variations in the air-fuel ratio can be effectively eliminated, and stable air-fuel ratio control is performed. Further, it is sufficient to prepare one two-dimensional map for the fuel temperature as the map for storing the learning value, and the storage amount may be sufficiently small.

The variation in the detected alcohol concentration is as follows:
Since the characteristic variation of the alcohol sensor 7 itself is considerably affected in addition to the fuel temperature, learning is performed for each area divided by the fuel temperature detected by the fuel temperature sensor 8 and the alcohol concentration detected by the alcohol sensor 7. Done, 3
If the learning value is stored for each corresponding area of the dimensional map, the air-fuel ratio control accuracy can be further improved.

FIG. 5 shows a temperature learning routine according to the second embodiment (an embodiment of the second aspect of the present invention). The fuel injection amount setting routine is common to that of FIG. 4 and will not be described. Steps 21, 23 to 27 are the same as steps 11, 13 to 16 in FIG.

[0024] At step 28, calculates a deviation [Delta] [alpha] _M of the average value alpha _M-1 of the average value alpha _M and the previous different temperature range of the feedback correction value at the current temperature range, which is calculated in step 27 . In step 29, the learning value ALC
LRN is corrected by the following equation using the deviation amount Δα _M ,
The learning value FTMLRN stored in an area determined by the current alcohol concentration in the RAM and the fuel temperature detected by the fuel temperature sensor 8 is rewritten.

FTMLRN ← FTMLRN + Δα _M / n (n> 1) In step 30, the count value of the counter C is reset to zero. If the temperature region has changed in the determination in 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, the deviation Δ of the average value of the air-fuel ratio feedback correction value between different alcohol temperature ranges is described.
Since the learning based on α _M is performed, the variation in the air-fuel ratio due to the fuel temperature can be more effectively eliminated, and the air-fuel ratio control control is improved.

[0027]

As described above, according to the present invention, since learning is performed for each fuel temperature range and the learned value is stored, the deviation of the air-fuel ratio due to the influence of the fuel temperature is effectively eliminated. And stable air-fuel ratio control accuracy can be obtained over the entire temperature range. Further, by performing learning based on the deviation of the average value of the air-fuel ratio feedback correction value between the temperature ranges, the learning is performed by more accurately extracting the variation in the air-fuel ratio due to the influence of the fuel temperature. It is possible to perform highly accurate air-fuel ratio control that more effectively eliminates variations in the air-fuel ratio between the two.

[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 temperature learning routine of the embodiment.

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

[Explanation of symbols]

1 engine 3 fuel injection valve 6 O ₂ sensor 8 fuel temperature sensor 9 Control Unit

Claims (2)

(57) [Claims] A fuel supply means for setting a basic fuel supply amount in accordance with an engine operating state; and a fuel supply means for causing an air-fuel ratio detected by an air-fuel ratio detection means under predetermined operating conditions to approach a target air-fuel ratio. A fuel supply control device comprising: an air-fuel ratio feedback correction unit that corrects a supply amount by a feedback correction value; and a fuel supply unit that supplies an amount of fuel corrected by the feedback correction value. And a magnitude relationship between an air-fuel ratio detected by the air-fuel ratio detecting means and a target air-fuel ratio after entering a plurality of temperature ranges according to the fuel temperature detected by the fuel temperature detecting means. Calculates the average value of the feedback correction values by the feedback control means until the value is inverted a predetermined number of times, and based on the average value, A learning value for correcting the basic fuel supply amount is set, a temperature learning means for storing the learning value in the temperature region of the storage device is provided, and the learning value corrected by the learning value stored in the corresponding temperature region of the storage device is provided. A fuel supply control device for an internal combustion engine, wherein the fuel supply amount is set using the fuel supply amount. 2. A fuel supply system comprising: a basic fuel supply amount setting means for setting a basic fuel supply amount in accordance with an engine operating state; A fuel supply control device comprising: air-fuel ratio feedback correction means for correcting the supply amount by a feedback correction value; and fuel supply means for supplying an amount of fuel corrected by the feedback correction value. The feedback control means from a time when the air-fuel ratio detected by the air-fuel ratio detection means is inverted by a predetermined number of times to a target air-fuel ratio after entering the temperature range divided into a plurality of areas according to the fuel temperature detected by Calculates the average value of the feedback correction value by using the average value in the temperature region and the average value in the different temperature region A learning value for correcting the basic fuel supply amount is set based on the deviation from the obtained average value, and a temperature learning unit for storing the learning value in the temperature region of the storage unit is provided. A fuel supply control device for an internal combustion engine, wherein a fuel supply amount is set using a basic fuel supply amount corrected by a learning value stored in a temperature region.