JPS631732A - Fuel control device for electronic fuel injection type engine - Google Patents

Abstract

PURPOSE:To improve drivability in a transient driving period, by correcting an amount of fuel injection based on transient correction values calculated for respective control means in the transient driving period when control means of an L-J (L-jetronic) system and a D-J (D-jetronic) system is switched in accordance with a driving condition for controlling an amount of fuel injection. CONSTITUTION:A fuel injection control device is provided with calculation means C for calculating an amount of fuel injection by an L-J system based on outputs from intake air flow amount sensing means A and engine r.p.m. sensing means B and calculation means E for calculating an amount of fuel injection by a D-J system based on outputs from the engine r.p.m. sensing means B and intake air pipe pressure sensing means D. There are also provided correction value calculation means G for calculating a first transient correction value for correcting an output from the calculation means C when an acceleration and deceleration timing is sensed and correction value correction means H for calculating a second transient correction value for correcting an output from the calculation means E by adding necessary correction to the first transient correction value. Then, correction means I, J correct outputs from the respective calculation means C, E based on the first and second transient values.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses the so-called L-Jetronic method when the engine load is smaller than a predetermined value, and the so-called D-Jetronic method when the engine load is larger than the predetermined value. The present invention relates to an improvement of a control device for an electronic fuel injection engine that controls the fuel injection amount using a Jetronic method, and more specifically, to an improvement of a control device for an electronic fuel injection engine that uses a Jetronic method to control the fuel injection amount. The present invention relates to a control device for an electronic fuel injection engine.

Prior art electronic fuel injection engine control devices currently include -
Generally, the so-called L-Jetronic method (hereinafter referred to as L-J
It's called a method. ) and the D-jetronic system (hereinafter referred to as D
-It is called the J method. ) are known.

The L-J method determines the fuel injection amount that provides the optimal air-fuel ratio according to the engine operating condition based on the detection output signal of an air flow sensor installed in the intake pipe upstream of the throttle valve and the detection output signal of an engine rotation speed detector. In this method, the opening time of the fuel injection valve is controlled H so that fuel is injected with this fuel injection amount. The airflow sensor commonly used with this method is equipped with a dynamic pressure measurement plate rotatably mounted in the intake pipe and a spring that biases this plate against the airflow. The amount of intake air is detected based on the displacement angle of the corresponding plate. For example, the amount of intake air when a carrot is running at full power is generally about 50 times as much as when it is idling. Since the amount of intake air generally fluctuates extremely, there is a problem in that it is difficult to detect the amount of intake air with high precision based on the displacement angle of one dynamic pressure measurement plate.

On the other hand, the D-J method detects the intake pipe pressure and engine speed, determines the amount of intake air per engine revolution based on these detection signals, and performs fuel injection that provides the optimal air-fuel ratio depending on the engine operating condition. This method calculates the fuel injection amount and controls the opening time of the fuel injection valve so that fuel is injected with this fuel injection amount. This method focuses on the fact that when the engine speed is constant, the amount of intake air is almost proportional to the pressure inside the intake pipe, and the fuel control circuit has in advance stored in memory the basic fuel injection for the amount of intake air according to the pressure inside the intake pipe. The basic fuel injection amount is memorized, and the fuel injection amount is determined by correcting this basic fuel injection amount based on the engine speed. However, when making corrections based on the engine speed, There was a problem in that the desired fuel injection amount could not be calculated with high accuracy because the correction coefficient was very large (varied).In other words, even if the intake pipe pressure and engine speed were determined, the engine operating condition could not be determined. The calculated intake air amount tends to deviate from the desired value depending on the engine speed and outside air conditions, and the deviation tends to be particularly large in the low-speed, low-load range. There was a problem with poor accuracy.

In order to compensate for the shortcomings of the L-J method and the D-J method and take advantage of their strengths, the L-J method is used when the amount of intake air is less than a predetermined amount, and the D-J method is used when the amount of intake air is more than the predetermined amount.
A control device for an electronic fuel injection engine that controls the amount of fuel injection using the -J method has been proposed in Japanese Patent Publication No. 7017/1983. This method has the advantage that the fuel injection amount that provides the optimum air-fuel ratio can be calculated with high accuracy despite the irregular fluctuations in the intake air amount, and the fuel injection amount can be optimally controlled.

Problems to be Solved by the Invention However, in the electronic fuel injection engine control device disclosed in Japanese Patent Publication No. 59-7017, the fuel injection amount is controlled to provide the optimum air-fuel ratio during engine transients. That was impossible. In other words, during a transient period, due to the inevitable response delay of the fuel injection amount control system, the amount of fuel to be injected at a certain point in time may not match the value calculated based on the engine operating state at a previous point in time. Therefore, there is a problem in that it is not possible to control the fuel injection amount so as to provide the optimum air-fuel ratio even during a transient period. L-j system, D-
It is an object of the present invention to provide a control device for an electronic fuel injection engine having a J-type switching system.

SUMMARY OF THE INVENTION It is an object of the present invention to detect L-
A means for calculating a transient correction value by the J method, a means for calculating a transient correction value by the D-J method, and a means for correcting the fuel injection amount calculated by at least the method to be selected based on the calculated transient correction value are provided. This is achieved by

In the present invention, correcting the fuel injection amount calculated by at least the method to be selected means the L-J method or the D
- After selecting one of the basic fuel injection amounts calculated by the J method, at least the case where the selected basic fuel injection amount is corrected based on the transient detection signal, and the transient detection signal before selecting one of the basic fuel injection amounts. This includes both cases where the basic fuel injection amount is corrected based on the detection signal and one of the corrected fuel injection amounts is selected. Even if the transient state of the engine is the same, that is, the intake air amount change rate is the same, L-
Since the transient correction value that corrects the fuel injection amount calculated based on the J method and the transient correction value that corrects the fuel injection amount calculated based on the D-J method are different, the transient correction value that corrects the fuel injection amount calculated based on the D-J method is different. The transient correction value is calculated using If only the amount is corrected, the fuel injection amount cannot be controlled to provide the optimum air-fuel ratio during a transient period.

Further, in the fuel injection amount control device of the present invention, it is preferable that the transient correction is performed both during acceleration and deceleration, but it is preferable that the transient correction is performed only in one of these cases. The present invention also covers such cases.

In one embodiment of the present invention, transient correction values necessary for calculating the fuel injection amount using the L-J method are obtained experimentally in advance for various transient conditions, and the transient correction values are calculated in the form of a table or the like. stored in a value calculation means, and calculates a transient correction value for the L-J method based on the transient detection signal;
D is a means for outputting this to the L-J method fuel injection amount correction means and calculating a transient correction value using the D-J method.
- Output to the J system correction value correction means, and cause the correction value correction means to correct the transient correction value to calculate a transient correction value for the DJ system, and output it to the DJ system fuel injection amount correction means. The basic fuel injection amount is corrected using these transient correction values by the L-J method and DJ method fuel injection amount correction means to calculate the fuel injection amount for each method, and then the intake pipe internal pressure is According to the detection signal, L-
By the J method/D-J method switching means, the L-J method,
The fuel injection amount is controlled by selecting any output value of the DJ type fuel injection amount correction means as the fuel injection amount.

In another embodiment of the present invention, first, one of the basic fuel injection amounts calculated by the L-J method and the DJ method is selected as the basic fuel injection amount according to the intake pipe internal pressure value, On the other hand, the output of the L-J method transient correction value calculating means is outputted to the transient correction value correcting means which also has a function of calculating a transient correction value for the D-J method, and the transient correction value correcting means is used to calculate the above-mentioned According to the intake pipe pressure value, L-J
When the fuel injection amount should be controlled by the method, that is,
The basic fuel injection amount selected as above is L-J
When the transient correction value is to be controlled by the DJ method, the transient correction value is output as is to the fuel injection amount correction means without any modification, and when the fuel injection amount is to be controlled by the DJ method, that is, when the selected basic fuel injection amount is , when the D-J method is used, necessary corrections are made to the transient correction value, a transient correction value for the D-J method is calculated and output to the fuel injection amount correction means, and the basic fuel is determined by the fuel injection amount correction means. The fuel injection amount is controlled by correcting the injection amount using the transient correction value.

Here, correction of the fuel injection amount is necessary during acceleration (well, there is a time delay in increasing the fuel injection amount, and the fuel injection type calculated at a certain point will inevitably be less than the desired fuel injection amount, so The injection amount is corrected to be larger than the calculated value. On the other hand, during deceleration, there is a time delay in reducing the fuel injection amount, and the calculated fuel injection amount at a certain point will inevitably be larger than the desired fuel injection amount. This is done by correcting the fuel injection amount so that it is smaller than the calculated value.

In addition, in the present invention, contrary to the embodiment described above,
The transient correction value required when calculating the fuel injection amount by the DJ method is experimentally determined in advance and stored in the transient correction value calculation means in the form of a table, etc. as the basic value, change L-J as necessary
Modifications may be made to the system and such embodiments are nevertheless included in the present invention.

Furthermore, the transient correction value calculated for the - method is corrected, and the transient correction value for the other method (instead of direct, L
=Means for calculating the transient correction value for the J method and D)-J
A means for calculating the error and the 9-correction value for the method may be provided independently, and such an embodiment is also included in the present invention.

EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention. The engine 1 includes a piston 3 that reciprocates within the cylinder bore 2, and a space above the piston 3 in the cylinder bore 2 constitutes a combustion chamber 4. An intake port 5 and an exhaust port 6 are respectively opened in the combustion chamber 4, and an intake valve 7 and an exhaust valve 8 are combined with the intake port 5 and the exhaust port 6, respectively. Furthermore, an intake passage 9 and an exhaust passage 10 communicate with the intake port 5 and the exhaust port 6, respectively.

An air cleaner 11 is installed at the upstream end of the intake passage 9, an air flow meter 12 is installed in the intake passage 9 downstream of the air cleaner 11, and a throttle valve 13 is installed downstream of the air flow meter 12. ) Fuel injection valves 14 are provided downstream of the fuel injection valves 13, respectively.

An air-fuel ratio sensor 15 is attached to the exhaust passage 10 for detecting the oxygen concentration in the exhaust gas and controlling the air-fuel ratio.

In the engine fuel supply system of this embodiment, fuel is introduced from a fuel tank 16 into a fuel pump 17, passes through a fuel filter 18, is regulated to a predetermined pressure by a fuel pressure regulator 19, and is sent to a fuel injection valve 14. In this embodiment, in order to control the fuel injection amount so as to obtain the optimum air-fuel ratio, a fuel injection amount control device 20 including a microcomputer is provided. The fuel injection amount control device 20 detects a signal indicating the opening degree θ of the throttle valve 13, an intake pipe pressure detection signal from an intake pipe pressure sensor 21 provided in the intake pipe downstream of the throttle valve 13, and an engine rotation speed. The crank angle signal from the crank angle sensor 22 and the oxygen concentration signal from the air-fuel ratio sensor 15 are input, and the fuel injection amount control device 20
These human input signals are calculated to calculate the fuel injection amount that provides the optimum air-fuel ratio, and the opening time of the fuel injection valve 14 is controlled.

FIG. 2 is a block diagram showing the configuration of an embodiment of the fuel injection amount control device 20 according to the invention.

In FIG. 2, the fuel injection amount control device 20 receives detection signals from intake air flow rate detection means such as an air flow meter, engine rotation speed detection means such as a crank angle sensor 22, and intake pipe pressure detection means such as an intake pipe pressure sensor 21. Based on the L-J method, the basic fuel injection amount τ is calculated based on the L-J method, and the DJ method is used to calculate the basic fuel injection amount τ6. Further, an acceleration/deceleration determination means for determining an acceleration/deceleration state based on an output signal of an intake air flow rate detection means such as the air flow meter 12 and/or a throttle valve opening detection means;
L-J method acceleration/deceleration correction value calculation means and L-J method acceleration/deceleration correction for calculating an acceleration/deceleration correction value for the fuel injection amount calculated according to the L-J method based on the output signal of the acceleration/deceleration determining means. Acceleration/deceleration correction 1 calculated by value calculation means
A DJ method correction value correction means is provided which directly adds necessary corrections and calculates an acceleration/deceleration correction value for correcting the basic fuel injection amount by the DJ method. Further, the fuel injection amount control device 20 adds acceleration/deceleration correction to the basic fuel injection amount τ calculated by the L-J method calculation means based on the output signal of the L-J method acceleration/deceleration correction value calculation means, - The D
- Basic fuel injection amount τ calculated by the J method calculation means.

A D-J method fuel injection amount correction means is provided for adding acceleration/deceleration correction to determine the fuel injection amount based on the D-J method, and the intake pipe pressure value detected by the intake pipe pressure detection means is equal to or higher than a predetermined value. According to the output signal of the intake pipe pressure determining means and the intake pipe pressure determining means, the determination result is output to the L-J method/D-' J method switching means. , when it is less than a predetermined value, the output value of the L-J method fuel injection amount correction means is selected as the fuel injection amount, and the output value of the D-J method fuel injection amount correction means is L-J method/DJ method switching means is provided for selecting the fuel injection amount and outputting it to the fuel injection amount control means.

FIG. 3 is a flowchart showing a control method in the fuel injection amount control device 20 shown in FIG. In FIG. 3, first, intake air flow rate data detected by intake air flow rate detection means such as air flow make 12, engine rotation speed data detected by engine rotation speed detection means such as crank angle sensor 22, and intake pipe pressure sensor Intake pipe pressure data detected by intake pipe pressure detection means such as 21 is inputted. Next, based on these input data, the basic fuel injection amount τ is calculated based on the L-J method by the L-J method calculation means, and the basic fuel injection amount τ is calculated in the form of injection time by the D-J method calculation means.
The basic fuel injection amount τ is calculated in the form of injection time based on the J method. Further, the acceleration/deceleration determination means determines whether or not the acceleration is state, deceleration state, or neither of these is determined, and the determination result is output to the LJ method acceleration/deceleration correction value calculation means. When a determination signal indicating that the acceleration/deceleration state is present is output, the L-J type acceleration/deceleration correction single-direction calculation means performs the acceleration/deceleration correction according to a correction algorithm that has been experimentally determined in advance and stored in the form of a table or the like. , calculate acceleration/deceleration correction values for the basic fuel injection amount based on the L-J method.

On the other hand, when the vehicle is not in an acceleration/deceleration state, the acceleration/deceleration correction value is set to zero. Next, the basic fuel injection amounts '1 and τ6 are corrected based on this correction value. The correction is L-
In the J method fuel injection amount correction means, the above correction value is used as is, but for the basic fuel injection amount obtained by the D-J method, the D-J method correction value correction means corrects the basic fuel injection amount obtained by the D-J method. p-J with the necessary modifications for use.
An acceleration/deceleration correction value for the system is calculated and output to the DJ system fuel injection amount correction means, and the basic fuel injection amount τ6 is corrected based on the corrected correction value thus obtained.

The thus corrected fuel injection amount values according to the L-J method and the DJ method are respectively output to the L-J method/DJ method switching means. On the other hand, the intake pipe pressure data P detected by the intake pipe pressure detection means is compared with a predetermined intake pipe pressure P0 by the intake pipe pressure determination means, and a determination signal is output to the L-J method/DJ method switching means. be done. The L-J method/D-J method switching means selects the output value of the L-J method fuel injection amount correction means as the fuel injection amount when the human power signal P from the intake pipe pressure determining means is P<Po. If P≧Pa, the output value of the DJ type fuel injection amount correction means is selected as the fuel injection amount. Furthermore, as shown in FIG. 3, after conventional corrections such as warm-up correction and battery voltage correction are performed as necessary, the signal is output to the fuel injection control means as a fuel injection control signal. Ru. The fuel injection control means receives this control signal.

FIG. 4 is a block diagram showing the configuration of another embodiment of the fuel injection amount side ill device 20 according to the present invention.

In Fig. 4, by the L-J method and the D-J method,
After calculating the basic fuel injection amounts τ5 and τ, respectively, the basic fuel injection amounts calculated by the L-J method and the DJ method are determined by the L-J method/DJ method switching means according to the intake pipe internal pressure value. One of τ6 and τ is selected as the basic fuel injection amount, and it is determined whether or not the acceleration/deceleration state is in the other,
In the acceleration/deceleration state, an acceleration/deceleration correction value for the basic fuel injection amount is calculated using the L-J method, and when the intake pipe pressure value is greater than a predetermined value, this acceleration/deceleration correction value is further calculated using the D-J method. Add the necessary corrections to correct the basic fuel injection amount,
In other words, if the value calculated by the L-J method is selected as the basic fuel injection amount, the value calculated by the L-J method is selected as the basic fuel injection amount.
The basic fuel injection amount τ is corrected by the correction value for the method, but if the value calculated by the D-J method is selected as the basic fuel injection amount, the correction for the L-'J method is After the correction necessary for use in the DJ system is added to the value, the basic fuel injection amount τ6 is corrected, and the fuel injection amount to be controlled is calculated.

Therefore, in FIG. 4, L
-L-J method/D- which selects either the basic fuel injection amount calculated by the J method or the D-J method calculation means
Based on the output of the J method switching means and the acceleration/deceleration determining means,
The fuel injection amount should be controlled by the L-J method based on the output signal of the L-J method acceleration/deceleration correction value calculating means and the intake pipe pressure determining means that calculate the acceleration/deceleration correction value of the basic fuel injection amount using the L-J method. When, that is, L-J method/D-J
When the method switching means selects the basic fuel injection amount by the L-J method, it outputs the correction value as it is without making any corrections, and on the other hand, when the fuel injection amount is to be controlled by the D-J method, i.e. , when the basic fuel injection amount based on the DJ method is selected, the correction value necessary for use in the DJ method is added to the correction value, and then an acceleration/deceleration correction signal is output to the fuel injection amount correction means. The acceleration/deceleration correction value correction means is provided.

FIG. 5 is a flowchart showing a control method in the fuel injection amount control device 20 shown in FIG. In FIG. 5, as in FIG. 3, first, intake air flow rate data detected by the intake air flow rate detection means, engine rotation speed data detected by the engine rotation speed detection means, and intake pipe pressure detection means are detected. The intake pipe internal pressure data is manually input. Next, based on these manually generated data, the basic fuel injection amount τ is calculated in the form of injection time based on the L-J method by the L-J method calculation means, and the D- The basic fuel injection amount τ6 is calculated in the form of injection time based on the J method. Next, the intake pipe internal pressure determining means compares and determines the intake pipe internal pressure data P detected by the intake pipe internal pressure detecting means with a predetermined intake pipe internal pressure value P0, and the determination signal determines whether the LJ system/DJ system is switched. Output to means. The L-J method/D-J method switching means is configured such that the input signal is P<Pa.
When P≧Pa, the output value τ of the L-J method calculation means is selected as the basic fuel injection amount value, and when P≧Pa, the output value τ of the D-J method calculation means is selected as the basic fuel injection amount value. Select as. Further, based on the intake air flow rate change rate and/or the throttle valve opening rate change rate calculated based on the output signal of the intake air flow rate detection means, the acceleration/deceleration determining means determines whether the state is accelerated, decelerated, or neither. The judgment result is output to the LJ method acceleration/deceleration correction single-direction calculation means. The L-J method acceleration/deceleration correction value calculation means calculates a correction value for the basic fuel injection amount according to the L-J method according to the acceleration/deceleration state, and outputs it to the acceleration/deceleration correction value modification means. The acceleration/deceleration correction value correcting means is manually supplied with a determination signal from the intake pipe pressure determining means as to whether or not the intake pipe internal pressure P is a predetermined pressure of 20 or more, and this signal is NOl, that is,
When P<Pa, the output signal of the L-J method acceleration/deceleration correction value calculation means is used as the output signal, and when YES, that is, P≧P0, the output signal of the L-J method acceleration/deceleration correction value calculation means is used as the output signal. After adding corrections necessary for using the DJ system to the signal, the signal is output to the fuel injection amount correction means. The fuel injection amount correction means corrects the basic fuel injection amount based on this signal, further adds necessary corrections such as warm-up correction, and outputs a fuel injection control signal to the fuel injection control means.

The fuel injection control means drives the fuel injection valve 14 based on this control signal, and controls its opening time so that a desired amount of fuel is injected.

It goes without saying that the present invention is not limited to the above embodiments, but can be modified in many ways within the scope of the invention described in the claims. For example, in the embodiment described above, the acceleration/deceleration correction value for the L-J method is stored in the fuel injection amount control device in advance, and the correction value for the L-J method is used as the basic value, and the acceleration/deceleration correction value for the L-J method is used as the basic value. When correcting the calculated basic fuel injection amount, a corrected correction value is used, but conversely, the acceleration/deceleration correction value for the DJ system is stored in the fuel injection amount control device. However, when this correction value for the DJ method is adopted as a basic value and the basic fuel injection amount calculated by the L-J method is to be corrected, this correction value may be modified and used.

Effects of the Invention According to the present invention, it is possible to compensate for the response delay that the fuel injection amount control system inevitably has during engine transients, thereby providing the optimum air-fuel ratio for drastic intake air amount fluctuations. It becomes possible to accurately calculate the fuel injection amount and optimally control the fuel injection amount.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention. 2 and 4 are block diagrams showing embodiments of the fuel injection amount control device of the present invention. It is a flow chart showing a control method in an example. 1e-ψ engine, 2... Cylinder bore, 3... Piston, 4... Combustion chamber, 5... Intake port, 6... Exhaust port, 9... ... Intake passage, 12... Air 70-meter, 13... Throttle valve, 14... Fuel injection valve, 20... Fuel injection amount control device, 21... Intake pipe internal pressure sensor, 22. ...Crank angle sensor.

Claims (1)

[Claims] An air flow meter installed in the intake system to detect the amount of intake air, a load detection means that outputs a signal corresponding to the intake negative pressure downstream of the throttle valve or the throttle valve opening, and an engine rotation speed detector to detect the engine rotation speed. means, first fuel control means for controlling the fuel injection valve based on the output of the air flow meter, and second fuel control means for controlling the fuel injection valve based on the outputs of the load detection means and the engine rotation speed detection means. and switching means for switching from fuel injection amount control based on the first fuel control means to fuel injection amount control based on the second fuel control means in an operating range where the intake air amount or engine load exceeds a predetermined value; transient detection means for detecting time; and first transient correction value calculation means for calculating a first transient correction value for correcting the fuel injection amount calculated by the first fuel control means based on the transient detection signal of the transient detection means. a second transient correction value calculation means for calculating a second transient correction value for correcting the fuel injection amount calculated by the second fuel control means based on the transient detection signal of the transient detection means; 1. A fuel control device for an electronic fuel injection engine, comprising at least a transient correction means for correcting the fuel injection amount calculated by the fuel control means to be selected.