JPS631733A - Fuel control device for electronic fuel injection type engine - Google Patents

Abstract

PURPOSE:To prevent an abrupt change in an amount of fuel injection, by providing means for gradually switching an amount of fuel injection in a 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. Further, there is provided a fuel injection amount correction means H. When switching determining means F determines YES in an event that an intake air pressure changes to the vicinity of a prescribed value, switching means G gradually switches a selected fuel injection amount to an injection amount corrected by an acceleration and deceleration correction value in a prescribed period of time. On the other hand, when the determining means F determines NO, the fuel injection amount is simply corrected by the acceleration and deceleration correction value to be deceleration correction value to be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention employs a so-called L-jetronic method when the engine load is smaller than a predetermined value, and a so-called D-jetronic method when the engine load is larger than a predetermined one shift. - This relates to an improvement in a control device for an electronic fuel injection engine that controls the amount of fuel injection using a Jetronic method, and more specifically, such a method that includes means for controlling the amount of fuel injection based on a transient detection signal. The present invention relates to a fuel 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. This method determines the fuel injection amount and controls the opening time of the fuel injection valve 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 the engine is running at full power is generally about 5.
In general, the amount of intake air fluctuates extremely widely, reaching as much as 0 times, so it is difficult to detect the amount of intake air with high precision based on the displacement angle of a single dynamic pressure measurement plate. There was a problem that.

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 has been a problem in that the desired fuel injection amount cannot be calculated with high accuracy because the correction coefficient varies greatly. In other words, even if the intake pipe pressure and engine speed are determined, the calculated intake air amount tends to deviate from the desired value depending on the engine operating state, outside air conditions, etc., and the deviation tends to be particularly large in the low rotation and low load region. However, the DJ system has a problem in that the accuracy of air-fuel ratio control is poor in the low-speed, low-load range.

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 it is possible to accurately calculate and control the fuel injection amount that provides the optimum air-fuel ratio even though the intake air amount fluctuates widely.

Problems to be Solved by the Invention However, in the electronic fuel injection engine control device disclosed in Japanese Patent Publication No. 59-7017, it is difficult to control the fuel injection amount so as to provide the optimum air-fuel ratio during engine transients. was not possible. In other words, during a transient period, due to the inevitable response delay of the fuel injection amount control system, the fuel injection amount to be injected at a certain point in time is a 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 to provide the optimum air-fuel ratio during a transient period.

In addition, when it becomes necessary to switch the fuel injection amount calculation method between the L-J method and the DJ method according to the engine operating condition, the L-J method and the DJ method can be switched. (There is a direct difference between the transient correction value for correcting the fuel injection amount by the L-J method and the transient correction value for correcting the fuel injection amount by the DJ method. Due to the difference in the fuel injection amount, it is inevitable that the fuel injection amount changes discontinuously and suddenly, making it impossible to smoothly control the fuel injection amount.

Purpose of the Invention The present invention makes it possible to control the fuel injection amount so as to provide the optimum air-fuel ratio even during a transient period, and also to control the fuel injection amount so that it changes smoothly.
An object of the present invention is to provide a fuel control device for an electronic fuel injection engine having a switching system between the -J method and the DJ method.

Structure of the Invention The object of the present invention is to provide a means for correcting the fuel injection amount based on a drug flow detection signal, and a means for immediately correcting a new fuel injection amount when switching the fuel injection amount calculation method between the L-J method and the D-J method. This is achieved by providing means for controlling switching of the fuel injection amount so that the fuel injection amount changes gradually without switching to the value calculated by the method.

Specifically, the nuclear fuel injection amount correction means adjusts the fuel injection amount because there is a time delay in increasing the fuel injection amount during acceleration, and the fuel injection amount calculated at a certain point will inevitably be less than the desired fuel injection 1. 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 at a certain point the calculated 8'F# injection amount may be less than the desired fuel injection amount. Since the amount will inevitably increase, the configuration is such that the fuel injection amount can be corrected to be smaller than the calculated value.

The control for switching the fuel injection amount is such that when the fuel injection amount calculation method is switched between the L-J method and the D-J method, the control changes from the previously calculated value to the currently calculated value. Although it is desirable that the fuel injection amount be changed gradually within a predetermined period of time, it is preferable to change the previously calculated value to the value calculated using the method before switching at the time when the fuel injection amount calculation method is switched. It may be approximated. Furthermore, any algorithm can be used to change the fuel injection amount within a predetermined period of time as long as the fuel injection amount changes gradually.

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 a 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, a throttle valve 13 is installed downstream of the air flow meter 12, 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 IO to detect the oxygen concentration in the exhaust gas and control 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 that an optimum air-fuel ratio is obtained, a fuel injection amount control device 20 preferably including a microcombination unit 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 word from the air-fuel ratio sensor 15 are input manually, 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 present invention.

In the embodiment shown in FIG.
L-J method calculation that calculates the basic fuel injection amount τ by the L-J method based on the detection signals of the engine rotation speed detection means such as the crank angle sensor 22 and the intake pipe pressure detection means such as the intake pipe pressure sensor 21. and a D-J method calculation means for calculating the basic fuel injection amount τ by the D-J method. Acceleration/deceleration determining means that determines the acceleration/deceleration state from the throttle valve opening change rate calculated based on the output signal of the throttle valve opening degree detection means and outputs the determination result to the L-J method acceleration/deceleration correction value calculation means; According to the output signal of the speed determination means, L-J
L-J method acceleration/deceleration correction value calculation means that calculates the acceleration/deceleration correction value for the system and outputs it to the acceleration/deceleration correction value correction means; A predetermined L-J method/DJ method switching pressure value P. an intake pipe pressure determining means for comparing and determining the magnitude of the difference between the Whether the judgment signal is different between the previous measurement and the current measurement, that is, the magnitude relationship between the intake pipe pressure value P detected by the intake pipe pressure detection means and the L-J method/DJ method switching pressure value Pa is determined from the previous measurement. Whether or not the time is reversed, in other words, the current detected value P , , + 1
and the previous detection value P. between (p, , , -po
) X (P, -PG) <0 is determined, and the determination signal is sent to the L-J method/DJ method switching means, acceleration/deceleration correction value correction means, fuel injection amount correction means, Switching determination means to output respectively; When the determination signal of the switching determination means is YES, outputs τ5, τ of the L-J method calculation means and the DJ method calculation means are both output to the fuel injection amount correction means. , On the other hand, in the case of No,
According to the intake pipe pressure value, one of the outputs τ5, τ of the L-J method calculation means and the DJ method calculation means is selected as the basic fuel injection amount, and L=J is output to the fuel injection amount correction means. Method/D-J method switching means: If the judgment signal of the switching judgment means is YES, the D-J method is applied to the acceleration/deceleration correction value output from the L-J method acceleration/deceleration correction value calculation means and this correction value. A correction value for the D-J system with necessary corrections added to calculate the fuel injection amount is output to the fuel injection amount correction means.On the other hand, in the case of No, the D-J method is adjusted according to the intake pipe pressure value. When the fuel injection amount should be corrected according to the method, the necessary corrections are made to the above correction value, and the L
- Acceleration/deceleration correction value correction means that outputs an acceleration/deceleration correction value to the fuel injection amount correction means without making any correction when the fuel injection amount should be corrected using the J method; In some cases, the basic fuel injection amount selected by the L-J method/DJ method switching means is corrected based on the acceleration/deceleration correction value calculated this time from the value calculated by the calculation method used last time. Arithmetic processing is performed so that the value gradually changes over a predetermined period of time, and NO
In this case, the fuel injection M correction means calculates the fuel injection amount by simply correcting the basic fuel injection amount selected by the L-J method/D-J method switching means using the acceleration/deceleration correction value calculated this time; A fuel injection control means is provided for controlling the opening time of the fuel injection valve 14 in accordance with a fuel injection amount control signal output from the fuel injection amount correction 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 an intake air flow rate detection means such as the air flow make 12, engine rotation speed data detected by an engine rotation speed detection means such as the crank angle sensor 22, and intake pipe pressure sensor. The intake pipe pressure data detected by the intake pipe pressure detection means such as 21 is manually inputted.

Next, based on these input data, the basic fuel injection amount is calculated in the form of injection time according to the L-J method by the L-J method calculation means, and the D - The basic fuel injection amount τ is calculated in the form of injection time based on the J method. Furthermore, the acceleration/deceleration determining means determines whether the acceleration is It is determined whether the vehicle is in a deceleration state, a deceleration state, or neither. As a result, when it is determined that the acceleration/deceleration state is present, the L-J method acceleration/deceleration correction value calculation means calculates the acceleration/deceleration correction value for the basic fuel injection amount based on the L-J method, and the acceleration/deceleration correction value correction means is output to. Here, when the vehicle is not in an acceleration/deceleration state, this correction value is set to zero. On the other hand, the intake pipe pressure data P detected by the intake pipe pressure detection means is compared and determined with a predetermined intake pipe pressure Po by the intake pipe pressure determination means, and the determination signal is sent to the L-J method/DJ method switching means. It is output to the acceleration/deceleration correction value correction means and the switching determination means.

The switching determination means compares the previous determination signal manually input from the intake pipe pressure determination means with the current determination signal, and determines whether or not the determination result is reversed, that is, the intake pipe pressure detection means has detected this time. Detected value P. , I and the previous detected value P. ,(Pi.1-Po)x(Pipo)<O
It is determined whether or not there is a relationship between
It is output to the DJ system switching determination means, the acceleration/deceleration correction value correction means, and the fuel injection amount correction means.

When the output signal of the switching determination means is YES, the L-J method/D-J method switching means controls both the basic fuel injection amount τ based on the L-J method and the basic fuel injection amount τ6 based on the DJ method. On the other hand, when the manual signal from the intake pipe pressure determining means is P < Pa, the output value τ of the L-J method calculation means is output to the fuel injection amount correction means. , is selected as the basic fuel injection amount, and when P≧P0, D
- The output value τ of the J method calculation means is selected as the basic fuel injection amount and outputted to the fuel injection amount correction means.

Further, when the output signal of the switching determination means is YES, the acceleration/deceleration correction value correction means uses the acceleration/deceleration correction value outputted from the L-J method acceleration/deceleration correction value calculating means and this correction value to fuel the fuel using the D-J method. The correction value for the DJ system with the necessary corrections for correcting the injection amount is output to the fuel injection amount correction means, and on the other hand, when NO, the correction value for the DJ system is outputted from the intake pipe pressure determination means according to the intake pipe pressure value. The input signal of P < P
o, the acceleration/deceleration correction value output from the L-J method acceleration/deceleration correction value calculation means is used as the correction value, and P
When ≧P0, a correction value for the DJ system, which is obtained by adding corrections necessary for use in the DJ system to the acceleration/deceleration correction value, is output to the fuel injection amount correction means as a correction value.

Furthermore, the L-J method/DJ method switching means, the acceleration/deceleration correction value correction means, and the switching determination means, respectively,
The fuel injection amount correction means that receives the above-mentioned signal is configured so that when the determination signal from the switching determination means is NO, that is, (Ph
, +po) × (Pn-Po)≧0, the basic fuel injection amount manually input from the L-J method/DJ method switching means is changed to the acceleration/deceleration correction (direct) input from the acceleration/deceleration correction value correction means. Calculate the fuel injection amount by correcting it by
A fuel injection amount control signal is output to the fuel injection control means. On the other hand, when the judgment signal from the switching judgment means is YES, that is, (Pfi, l - Pa')
h - Po ) When 0, the L-J method/DJ method is switched after a predetermined period of time from the first shift of the fuel injection amount calculated at this point by the fuel injection amount calculation method used last time. so that the basic fuel injection amount manually input this time from the means is gradually switched to 1 shift corrected by the j [l deceleration correction value manually input this time from the acceleration/deceleration correction value correction means,
The fuel injection amount is calculated and a control signal is output to the fuel injection control means so that the fuel injection amount gradually increases or decreases over time. In one specific example of this time control of the fuel injection amount, for example, when switching the calculation method of the fuel injection amount from the L-J method to the DJ method, the switching calculation ■ is executed in FIG. , the control value τ of the fuel injection amount at each time point is the acceleration/deceleration correction 1 for the L-J method.
Assuming that the direct speed is α, and the acceleration/deceleration correction value for the D-J method is α6,
It is controlled as shown below.

τ-((1-k)(τ, +α,) +k(τ, +α,)) Here, k is a switching coefficient that is a function of time, and is changed from zero to 1 after a predetermined time elapses, for example. , those that change linearly are selected. In addition, the above τ5, 1, α5
Since α and α are also functions of time and τ, in this example, the fuel injection amount after a predetermined period of time is the basic fuel injection amount calculated at the time the L-J method and DJ method are switched. and the fuel injection amount value determined from the acceleration/deceleration correction value.
The fuel injection amount after △ has passed from the start of this switching calculation is:
Calculated according to the above formula based on the basic fuel injection amount and acceleration/deceleration correction value by the LJ method and D-J method calculated after △, and after time t-△ (time after the start of switching calculation) The so-called target fuel injection amount is also set to a different value as time passes. Also,
Before a predetermined period of time elapses after this switching calculation is started, the intake pipe pressure value P changes again to (pn, + -Pa) x
When (P, -PG) <0 is satisfied, in this example, when switching from the D-J method to the L-J method, in the above equation, τ(and τd1α, and α) , respectively, the replaced switching operation ■ will be executed.

First, when switching from the DJ system to the L-J system, and then from the L-J system to the DJ system, the operation opposite to that described above, that is, the switching operation ■ is performed first. Then, following this, the switching operation ■
will be executed.

The fuel injection amount control signal that has undergone acceleration/deceleration correction in this way is
Although outputted to the fuel injection control means, in addition to acceleration/deceleration correction, conventional corrections such as warm-up correction and battery voltage correction may also be performed as shown in FIG.

The fuel injection control means that receives the fuel injection amount control signal from the fuel injection amount correction means drives the fuel injection valve 14 in accordance with the signal and controls the amount valve time.

It goes without saying that the present invention is not limited to the above embodiments, but can be modified in various ways within the scope of the invention described in the claims.

For example, in the above embodiment, the acceleration/deceleration correction value for the L-J method is calculated, and the acceleration/deceleration correction value for the D-J method is calculated by adding necessary corrections for use in the D-J method. However, on the contrary, calculate the acceleration/deceleration correction value for the D-J method,
The acceleration/deceleration correction value for the L-J method may be calculated by adding the necessary corrections for use in the L-J method. When calculating a correction value and using it for another method, instead of correcting it and using it as a correction value, calculate the acceleration/deceleration correction value for the L-J method and the D-J method respectively. You can also. Furthermore, in the above embodiment, the switching calculation is performed using the value of the fuel injection amount calculated by the fuel injection amount calculation method used last time at that point as the reference value, but the previous fuel injection amount (actual The value obtained by removing corrections other than acceleration/deceleration correction from the fuel injection amount injected at , it is also possible to perform switching calculations using this value as a reference value.

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 a transient period, so it is possible to maintain the optimum air-fuel ratio in response to drastic intake air type fluctuations. It becomes possible to calculate the fuel injection amount with high accuracy and to 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. FIG. 2 is a block diagram showing an embodiment of the fuel injection amount control device of the present invention, and FIG. 3 is a flowchart showing a control method in the embodiment of FIG. DESCRIPTION OF SYMBOLS 1... Engine, 2... Cylinder bore, 3... Piston, 4... Combustion chamber, 5... Intake boat, 6... Exhaust port, 9... Intake passage, 12... Air flow meter, 13... Throttle valve, 14... Fuel injection valve, 20... Fuel injection amount control device, 21... Intake pipe internal pressure sensor, 22... Crank angle sensor. , 11 Figure 1

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. a switching determination means that determines whether the intake air amount or engine load fluctuates around a predetermined value and outputs a switching determination signal; a transient detection means that detects a transient state of the engine; first transient correction signal 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 from the transient detection means; a second transient correction signal calculating 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 correction value; and a fuel calculated by the first fuel control means based on the transient correction value. correcting the injection amount and/or the fuel injection amount calculated by the second fuel control means and controlling the fuel injection amount based on the first fuel control means based on the switching determination signal output from the switching determination means; Fuel for an electronic fuel injection engine, characterized in that it is equipped with a switching control means for controlling the fuel injection amount so that the fuel injection amount control method is gradually switched between the fuel injection amount control based on the fuel control means and the fuel injection amount control method based on the fuel control means. Control device.