JPS58133435A - Electronically controlled fuel injection method of internal-combustion engine - Google Patents

Abstract

PURPOSE:To compatibly obtain acceleration and deceleration performance and exhaust gas purifying performance, by performing suitable decrease correction combined with a throttle valve opening decrease and intake pipe pressure decrease at the time of deceleration to maintain air fuel ratio in the vicinity of the logical air fuel ratio in an electronically controlled fuel injection device of intake pipe pressure type. CONSTITUTION:At operation of a deceleration decrease, whether an idle switch of a throttle sensor is turned on or not is decided. If a decision result is positive, that is, a throttle valve is fully closed, whether speed of an engine is a prescribed value, for instance, 1,000rpm or less or not is decided. If a decision result is positive, whether in a state of deceleration decrease, that is, TA (throttle valve opening) decrease or PM (intake pipe pressure) decrease is decided. If a decision result is positive, a value of correction coefficient F is forcibly returned to 0 to suspend the deceleration decrease. While the decision result is negative, that is, even in a state of deceleration decrease, when the idle switch is turned on or the speed of the engine exceeds 1,000rpm, the deceleration decrease is continued.

Description

[Detailed description of the invention] This invention I! II:I relates to an electronically controlled fuel injection method for an internal combustion engine, and in particular, to an engine intake pipe pressure and engine rotation suitable for use in an automobile internal combustion engine equipped with an intake pipe pressure type electronically controlled fuel injection device. This invention relates to an improvement in an electronically controlled fuel injection method for an internal combustion engine, in which the basic injection amount is determined according to the engine operating condition, and the fuel injection amount is determined by correcting the basic injection amount according to the engine operating state during transient times. .

One of the methods for supplying an air-fuel mixture with a predetermined air-fuel ratio to the combustion chamber of an internal combustion engine such as an automobile engine is to use an electronically controlled fuel injection device. This means that the fuel t-
For example, H1 injectors for injecting V-injection are arranged in the intake manifold or throttle body of the engine for several engine cylinders, and the valve opening time of the injectors is controlled according to the operating state of the engine. The air-fuel mixture is supplied to the engine combustion chamber with an air-fuel ratio of . This electronically controlled fuel injection device VC can be roughly divided into a so-called intake air amount type electronically controlled fuel injection device that determines the basic injection amount according to the amount of intake air of the engine and the engine speed, and an electronically controlled fuel injection device of the engine intake pipe. The basic injection amount is calculated according to pressure and engine speed.

There is a so-called intake pipe pressure type electronically controlled fuel injection device.

Among these, the former allows for precise control of the air-fuel ratio, and is now widely used in automobile engines equipped with exhaust gas purification measures.

However, in this intake air volume type electronically controlled fuel injection system, the intake air volume increases by about 50 times when idling and under high load, and the dynamic range is wide, so when converting 1k of intake air into an electrical signal, Not only will the accuracy of the calculation become lower, but if you try to increase the calculation accuracy in the digital control (b) path at the subsequent stage.

The pit length of the electric signal becomes long, and an expensive computer needs to be used as a digital control circuit.

Father, T & PopularityIn order to measure airflow, it was necessary to use a measuring device with a very precise structure, such as an air flow meter, which led to problems such as high equipment costs.

On the other hand, the latter intake pipe pressure type electronically controlled fuel injection device l1
In IVC, the amount of change in intake pipe pressure is small, about 2 to 3 times, and the dynamic range is narrow, so calculation processing in the digital control circuit at the subsequent stage is not only easy, but also
The pressure sensor for detecting the intake pipe pressure is also characterized by being inexpensive. However, compared to electronically controlled fuel injection systems that use intake air flow, the control accuracy of the air-fuel ratio is lower, and especially during deceleration, the fuel injection amount does not decrease unless the intake pipe pressure decreases, so the air-fuel ratio Not only does this temporarily become rich and reduce deceleration performance, but the amount of carbon monoxide in the exhaust gas increases, making it difficult to maintain the air-fuel ratio within a predetermined range suitable for a three-way catalytic converter. It was difficult. Even when the fuel injection amount is feedback-controlled in accordance with the output signal of the oxygen concentration sensor disposed downstream of the exhaust gas, the same problem occurs because the response of the oxygen concentration sensor is slow. Therefore, conventionally, it has been considered difficult to use intake pipe pressure type electronically controlled fuel injection devices in automobile engines that require precise control of the air-fuel ratio and that require exhaust gas purification measures. was.

In order to eliminate the above-mentioned drawbacks, it may be possible to perform a reduction correction during deceleration, but if this deceleration reduction is continued even when the speed approaches the idle speed, it will be difficult to correct the There is a possibility that the engine speed drops below the idle speed, causing discomfort to vehicle occupants, or, in extreme cases, causing KFi and engine stall.

In order to solve the above-mentioned conventional drawbacks, the present invention can prevent a drop in engine speed or an engine stall when transitioning to an idling state, thus achieving both good deceleration performance and exhaust gas purification performance. An object of the present invention is to provide an electronically controlled fuel injection method for an internal combustion engine that can perform the following steps.

The present invention determines the basic injection amount according to the intake pipe pressure and engine speed of the engine, and at the time of transient, the fuel injection amount is determined by correcting the basic injection amount according to the engine operating condition IIK. In the electronically controlled fuel injection method of the internal engine, during deceleration (while performing the reduction correction and the skeleton deceleration reduction!), when the throttle valve is fully closed and the engine speed is below a predetermined value, The above objective is achieved by canceling the deceleration reduction.

Further, the predetermined value is set to an engine speed slightly higher than the idle speed.

Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment of an intake pipe pressure type electronically controlled fuel injection device in which the electronically controlled fuel injection method for an internal combustion engine according to the present invention is adopted is as follows:
As shown in FIGS. 1 and 2, a ninth air cleaner 12 that takes in outside air, an intake temperature sensor 14 for detecting the temperature IJj' of the intake air taken in from the air cleaner 12, and a It was arranged to open and close in conjunction with the accelerator pedal (not shown) arranged in the driver's seat. Throttle valve 1B for controlling the flow rate of intake air
, a throttle sensor 2o including an idle contact for detecting whether or not the throttle valve 18 is in the idle open position f, and a potentiometer that generates a voltage proportional to the open position of the throttle valve 18; and a surge tank 22. And Mukuro Surge Tank 2
An intake pipe pressure sensor 23 for detecting the intake pipe pressure from the pressure inside the throttle valve 18i, a bypass passage 24 that bypasses the throttle valve 18i, and an intermediate part of the bypass passage 24 are disposed.

An idle rotation control valve 26 for controlling the idle rotation speed by controlling the opening area of the bypass passage 24, and an idle rotation control valve 26 for controlling the idle rotation speed by controlling the opening area of the bypass passage 24;
An injector 3o for injecting fuel toward the intake boat 3o and an exhaust manifold 32 are provided. an oxygen installed sensor 34 for detecting the air-fuel ratio based on the residual oxygen concentration in the exhaust gas; a 93-way catalytic converter 38 disposed midway in the exhaust pipe 36 on the downstream side of the exhaust manifold 32;
The distributor 40 has a distributor shaft that rotates in conjunction with the rotation of the crankshaft of the engine IO, and the distributor 40 has a built-in distributor. A top dead center sensor 42 and a crank angle sensor 44 output a top dead center signal and a crank angle signal according to the rotation of the distributor shaft, and a top dead center sensor 42 and a crank angle sensor 44 are arranged to detect the engine cooling water temperature while the engine is running. a cooling water temperature sensor 46, a vehicle speed sensor 5o for detecting the vehicle running speed 1&' from the rotational speed of the output shaft of the continuous shooting 48, and the intake pipe pressure sensor 2.
The engine rotation speed determined from the three outputs of intake pipe pressure and the output of the crank angle sensor 44 (accordingly, the basic injection IR per engine stroke is determined from the map, and this is calculated from the output of the throttle sensor 20 and the oxygen concentration). By correcting the air-fuel ratio output from the sensor 34 and the engine cooling water temperature output from the cooling water temperature sensor 46, the fuel injection amount is determined and a valve opening time signal is output to the injector 30. Determines the ignition timing according to the operating state and outputs an ignition signal to the igniter-equipped coil 52,
Furthermore, the intake air of the automobile engine 1o is equipped with a digital control circuit 54 that controls the idle rotation control valve 26 during idle! 'In pressure type electronically controlled fuel injection system,
In the digital control circuit M54, the throttle valve opening 1 is detected from the potentiometer output of the throttle sensor 2°.
According to the rate of decrease in the intake pipe pressure and the rate of decrease in the intake pipe pressure detected from the output of the intake pipe pressure sensor 23, a reduction correction is made during deceleration, and the throttle valve is fully closed during the execution of the deceleration reduction. and the engine speed is a predetermined value C that is slightly higher than the idle speed (for example, 1000 rPrn).
When it becomes below.

The above-mentioned deceleration reduction is discontinued.

As shown in detail in FIG. 2, the digital control circuit 54 includes a central processing unit (hereinafter referred to as a CPU) 60 consisting of a microprocessor that performs various arithmetic operations, a temperature sensor 14 . Potentiometer of throttle sensor 20, intake pipe pressure sensor 23, oxygen concentration sensor 34.
Analog signal input from cooling water temperature sensor 46,
An analog input port 2 with a multiplexer for converting into a digital signal and sequentially inputting it into the CP060, an idle contact of the throttle sensor 20, a top dead center sensor 42,
A digital input controller 4 is used to input digital signals inputted from the crank angle sensor 44, vehicle speed sensor 50, etc. to the CPU 60 at a predetermined timing, and a read-only memory (hereinafter referred to as "read-only memory") is used to store all programs and various constants. (referred to as ROM) 66 and the calculation data etc. in the CPU 60 are temporarily stored in Kf! A random access memory (hereinafter referred to as RAM) 68 for storing data, and a backup random access memory (hereinafter referred to as RAM) 68 that can be supplied with power from an auxiliary power source and retain data even when the engine is stopped.
(hereinafter referred to as backup RAM) 70, and CPU 6 (hereinafter referred to as backup RAM).
The results of the calculations in the idle rotation control valve 26.1 are sent to the idle rotation control valve 26. It is comprised of a digital output port door 2 for outputting to the injector 30, the igniter-equipped coil 52, etc., and a common bus 74 that connects each of the above-mentioned components.

The action will be explained below.

First, the digital control circuit 54 calculates the basic injection time TP from a map stored in advance in the ROM 66 based on the intake pipe pressure PM output from the intake pipe pressure sensor 23 and the engine speed NE calculated from the output from the crank angle sensor 44. (P
Procure M%NEI.

Furthermore, the fuel injection time TAU is calculated by correcting the basic injection time TP (PM, NE l) using the following equation according to the signals from each sensor.

TAU = TP (PM, NE) books (1+ *F)...
(1) Here, F is a correction coefficient; when F is positive, it represents an increase correction, and when F is negative, it represents a decrease correction. This is a correction magnification for further correcting the correction coefficient F, and is normally set to 1.

A fuel injection signal corresponding to the fuel injection time TAU thus determined is output to the injector 30, and the injector 30 is opened for the fuel injection time TAU in synchronization with the engine rotation, and the intake manifold 2 of the engine IO is opened.
Fuel is injected into the 8.

The deceleration region t in this embodiment is performed as follows.

That is, as shown in FIG. 83, one time t occurs during deceleration.

When the throttle valve 18 begins to close at , the throttle valve opening i[TA is rapidly reduced according to the decreasing speed of the throttle valve opening i[TA, as shown by the solid line A in FIG. A throttle valve opening reduction 1111 (hereinafter referred to as TA reduction) is performed. For this TA reduction, specifically 1, for example, throttle valve opening f
The value (negative value) obtained by integrating the pressure integrated value according to the amount of change in TA for each predetermined time is used as the correction coefficient F. Next, the predetermined level of salt is adjusted at high speed at every engine rotation or every fixed time, after reaching the predetermined level. This is done by recovering to 0 at low speed and multiple speeds 1 for a predetermined number of times.

Next, when the intake pipe pressure PM starts to decrease, from time t, the result appears in #143 (6)! As shown by IB, intake pipe pressure reduction (hereinafter referred to as PM reduction) is performed to perform a highly accurate reduction correction according to the decrease in intake pipe pressure PM.

This PM#1itl! :,in particular.

For example, integrate the integrated value according to the amount of change in the intake pipe pressure PMO for each required time, set 900 million (negative value) as the correction coefficient F, and then set the predetermined level of salt at each engine revolution or every fixed period of time at high speed. , after reaching a predetermined level, the slow IF constant recovery speed is reduced to 0.
This is done by restoring it to a certain point.

In addition, there are nine cases in which TA weight loss and PM weight loss overlap.

If both are used together, there is a risk of excessive weight loss. Therefore,
In this embodiment, as shown by the thick solid line in FIG.
One time t, following the minimum value of the TA weight loss and PM weight loss,
At ~t3, only TA reduction was performed.

At time ts''-, only PM reduction is performed.

In addition, during the TA reduction and PM reduction described in 1iit I, the throttle valve 18 is fully closed during deceleration reduction and capping, and the engine rotation speed is set to a constant value 1 that is slightly higher than the idle rotation speed, for example, 11000 rpm or less. When this occurs, the deceleration region 1 is discontinued. Specifically, as shown in FIG. 4, first, in step 101, it is determined whether the idle switch of the throttle sensor 20 is on. If the determination result is positive, that is, if the throttle valve 18 is fully closed, the process proceeds to step 102, where it is determined whether the engine speed is below a predetermined value, for example 11,000 rpm.

If the determination result is positive, tIc is executed in step 103iC.
Then, it is determined whether or not the deceleration reduction is in progress, that is, the TA reduction is in progress. If the determination result is positive, the process proceeds to step 104, where the value of the correction coefficient F is forcibly returned to 0, and the process is stopped in the deceleration region 1. On the other hand, the aforementioned Stella 7
If the determination result of any one of 101 to 103 is negative,
In other words, even if the deceleration reduction is being executed, the idle switch is off or the engine speed is 1100 Or
When the value exceeds p, the deceleration reduction is continued without being stopped.

FIG. 5 shows an example of the relationship between the engine speed NE and the correction coefficient F during deceleration reduction in this embodiment.

As is clear from the solid line C in FIG. 5, in this embodiment V, the deceleration reduction is stopped at time t1 when the engine speed NE reaches 1000 rprn, and the correction coefficient F is forced to 0.
[Because of this, the engine speed NE may fall below the idle speed Wrb, as shown by the broken line in Figure 5, or, as shown by the dashed line E in Figure 5,
The engine never stalls.

As described above, appropriate weight loss can be achieved by performing deceleration weight reduction by combining quick response TA reduction and highly accurate PM weight reduction.

By maintaining the air-fuel ratio near the stoichiometric air-fuel ratio, it is possible to achieve both deceleration performance and exhaust gas purification performance.

In the above embodiment, the deceleration weight loss was performed by combining the TA weight loss and the PM fiber reduction weight loss, but the combination of the deceleration weight loss is not limited to this.

According to the present invention, an appropriate reduction correction can be made during deceleration, the air-fuel ratio is maintained near the stoichiometric air-fuel ratio, and the deceleration state is changed to an idling state of 1II.
By smoothing the change in engine rotation during K transition, it is possible to achieve both good deceleration performance and exhaust gas purification performance. Therefore, even when an intake pipe pressure type electronically controlled fuel injection device is used, there is an excellent effect that precise air-fuel ratio control can be performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an intake pipe pressure type electronically controlled fuel injection device for an automobile engine in which the electronically controlled fuel injection method for an internal combustion engine according to the present invention is adopted. FIG. 3 is a block diagram showing the configuration of the digital control circuit used in the example, FIG. The flowchart of the program, FIG. 5, is also a diagram 111 showing an example of changes in the engine speed and the correction coefficient when transitioning from the deceleration state to the idle link state. 10... Engine, 14... Intake temperature sensor, 18.
...Aperture IF', 20...Throttle sensor, 23...
・Intake pipe pressure sensor, 30...Injector, 34・
...Oxygen concentration sensor, 40...Distributor,
42...Top dead center sensor, 44...Crank angle sensor, 46...Cooling water temperature sensor, 54...Digital control circuit. Agent Takaya Ron (and 1 other person) #73 Kuni (A' name: t ON-11-1-t.

Claims (1)

[Claims] (The basic injection amount is determined according to the engine intake pipe pressure and engine speed, and during transient periods, the fuel injection amount is determined by correcting the basic injection amount according to the engine operating condition.) Nine internal combustion engine electronics 111
In the 1 m fuel injection method, a reduction correction is performed during deceleration5.
In addition, during the execution of the deceleration reduction, the throttle valve is in a fully closed state, and the predetermined value of the engine rotation speed (2) 111T is set to be an engine rotation speed slightly higher than the idle rotation speed. The electronically controlled fuel injection method for an internal combustion engine according to item 1.