JPS59141730A - Method of controlling fuel injection quantity of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent excessive injection of fuel, by selecting the decremental rate of fuel injection quantity increasing rate at the time when the engine temperatureis low such that it is increased as the temperature of intake air is raised. CONSTITUTION:At a step 102, a fuel increasing rate at the time when the engine temperature is low is determined by correcting a datum injection quantity of fuel on the basis of the output of a water-temperature sensor. At a step 108, an attenuation factor k1 corresponding to the temperature of intake air is obtained on the basis of the output of a sensor for detecting the temperature of intake air, and the fuel increasing rate is decreased by a value k1. By employing such a method, it is enabled to improve the engine performance at the time when the engine temperature is low, without causing increase of emission at the time when temperature is normal.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a fuel injection amount control method for an internal combustion engine, and in particular,
The present invention relates to a fuel injection amount control method for an internal combustion engine suitable for controlling the fuel injection amount of a vehicle engine equipped with an electronic fuel injection device.

[Prior art]

In vehicle engines equipped with electronic fuel injection systems, various types of fuel increase controls are performed, including increasing fuel when the engine is cold, increasing fuel when starting, increasing fuel after starting, and increasing fuel during acceleration. There is. Among these, increasing the amount of twisting port when the engine is cold is a control equivalent to a carburetor choke.

To increase the amount of fuel when the engine is cold, calculate the basic fuel injection amount from the intake air when the engine is cold, correct the calculated basic fuel injection amount based on the engine water temperature, and increase the amount of fuel to exceed the basic fuel injection amount. The zero period value of the fuel injection amount is set, and this set zero period value is gradually reduced to the basic fuel injection amount at a constant rate every engine rotation, and the fuel is injected at an injection amount corresponding to the decrease in the initial value. Traditionally, injection has been carried out.

By the way, generally speaking, the lower the engine temperature, for example the engine water temperature, the longer it takes for the combustion state of the engine to become normal. On the other hand, at room temperature, the combustion state of the engine returns to normal in a short period of time. Therefore, the engine water temperature is 80-9
At low temperatures such as 0°C, it is necessary to increase the amount of fuel for a longer period of time than at room temperature.

However, if the ratio of the initial value attenuation amount of the fuel injection amount is adapted to the engine condition at low temperature, the fuel increase time at room temperature becomes long, leading to an increase in engine tension. Therefore, the effective value of the fuel injection amount is determined as a damping rate that is adapted to the engine condition at room temperature, and the initial value is reduced at a constant rate for each engine/revolution to prevent an increase in fuel emissions. An injection amount control method was used.

However, if the fuel increase is controlled at the rate of marginal value attenuation that matches the operating condition at room temperature, the fuel increase time will be shortened when the engine is cold, resulting in worsening of drivability when the engine is cold. There was a problem with that.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a fuel injection amount control method for an internal combustion engine that can improve drivability when the engine is cold.

[Summary of the invention]

In order to achieve the above object, the present invention calculates the basic fuel injection amount from the intake air amount when the engine is cold, and corrects the calculated basic fuel injection amount based on the engine water temperature to exceed the fuel injection amount. The initial value of the fuel injection amount as a fuel increase is set, and this set 0-stage value is gradually reduced to the basic fuel injection amount according to the accumulation of engine rotation, and the fuel is injected at an injection amount corresponding to the decrease in the initial value. In the method for controlling the amount of fuel injected into an internal combustion engine, the ratio of the marginal value attenuation of the fuel injection lid is set as a attenuation rate that increases as the intake air temperature rises over a temperature change range when the engine is cold. - When the initial value of the fuel injection amount is set in advance, the intake air temperature is detected, and the set initial value of the fuel injection amount is adjusted to the engine speed based on the attenuation rate according to the intake air temperature. The fuel injection amount is gradually reduced to the basic fuel injection amount according to the accumulation of the fuel injection amount.

[Embodiments of the invention]

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a preferred embodiment of the present invention.

In FIG. 1, the intake system of the engine 10 includes an intake temperature sensor 12 that detects the temperature of intake air, a near flow meter 4 that detects the amount of intake air, and a throttle position sensor 16 that detects the opening degree of the throttle valve. is provided'
There is. Air taken in through the air cleaner 18 opens the air flow meter 14 and the throttle valve 20, is supplied to the intake manifold 22, and is mixed with fuel injected from the injector 24. The mixer is supplied to a combustion chamber 28 through an intake valve 26, burned and exhausted by a spark plug 32 provided in a cylinder head 30, and discharged through an air valve 34 to an exhaust system.

Further, the cylinder block 36 is provided with a water temperature sensor 38 that detects the engine water temperature.

Further, the distributor 42 that distributes the ignition signal from the igniter 40 to each cylinder has a built-in rotation angle sensor 44 for detecting the engine rotation speed.

Intake temperature sensor 1 that detects various operating states of engine 10
2. Detection outputs of various sensors such as the air flow meter 14 and outputs of the ignition switch 46 and vehicle speed sensor 48 are supplied to the control device 50.

The control device 50 includes an A/D converter 52, an input interface circuit 54, a constant voltage power supply 56, a CPU 58, and an R
OM60, RAM62, output interface circuit 64
It consists of an A/D converter 52, an input interface circuit 54, cptr5B, ROM60, R
The AM 62 and the output interface circuit 64 are connected by a pass line 66, respectively.

Intake temperature sensor 12, air flow meter, water temperature setting 38
Each detection output is supplied to an A/D converter 52. Also, a throttle position sensor, a rotation angle sensor 44, an ignition switch 46, and a vehicle speed sensor 4.
Each detection output of 8 is supplied to a large sword interface circuit 54.

The igniter 40 is capable of providing an ignition signal to the distributor 42 by a control signal provided from the output interface circuit 64. Further, the injector 24 can control the fuel injection time by a control signal supplied from the output interface circuit 14.

In addition, the ROM 60 contains numerical data of fuel injection time corresponding to various operating conditions of the engine, numerical data of basic fuel injection amount corresponding to intake air amount, and as shown in FIG. Data of the initial value of the corresponding fuel injection amount is stored.

Here, in the present invention, the ratio of the initial value attenuation amount of the fuel injection amount is predetermined as a damping rate that increases as the intake air amount increases over a temperature change range when the engine is cold, and the fuel injection amount is When the initial value of the fuel injection amount is set, the initial value of the fuel injection amount set based on the attenuation rate according to the intake air temperature is gradually reduced to the basic fuel injection amount according to the cumulative engine rotation. Therefore, in this embodiment, as shown in FIG. 3, the attenuation rate indicating the ratio of the initial value attenuation amount of the fuel injection amount is 1 for non-idling and 2 for idling. and each damping rate kl, k2
Numerical data is stored in the ROM 60. Each of the damping rates kl and k2 is determined over a temperature change range when the engine is cold as a characteristic that increases as the intake air temperature rises.

The present embodiment has the above configuration, and its operation will be explained next.

The flowchart of FIG. 4 shows a processing routine when the present invention is applied to the system of FIG. 1.

In FIG. 4, first, in step 100, a basic fuel injection amount is determined based on the detected output of the air flow meter 14, and the process moves to step 102. In step 102, the basic fuel injection amount calculated in step 100 is corrected based on the detection output of the water temperature sensor 38 to set an initial value of the fuel injection amount as a fuel increase that exceeds the basic fuel injection amount. That is, as shown in FIG. 2, the initial value of the fuel injection amount is set according to the engine water temperature. Next step 1
04, it is determined whether or not to increase the amount of fuel when the engine is cold. That is, in step 104, it is determined whether the initial value WL calculated in step 102 exceeds the lower limit value WLmi. In this step YFi8
When it is determined that the initial value W is the lower limit value WLmi, the fuel amount is not increased when the engine is cold, so the process moves to the next step.

If No is determined in step 104, initial value WL>lower limit W
When it is Lmi, the process moves to step 106.

In step 106, it is determined whether or not the vehicle is idling based on the detection output of the throttle position sensor 16. If the determination in this step is No, and the time is not idle, the process moves to step 108. In step 108, based on the detection output of the intake air temperature sensor 12, 1 is set to the attenuation rate corresponding to the intake air temperature shown in FIG.
Take in from 0 and set WL −k, to the new initial value WL
, and move on to other processing. W period value WL is WL
-k, the fuel injection time of the injector 24 is also set corresponding to the ratio of the initial value attenuation amount of the fuel injection amount. Therefore, except when the engine is idling when the engine is cold, the fuel injection amount as a fuel increase is gradually reduced to the basic fuel injection amount according to the cumulative engine rotation based on the attenuation rate calculated in step 108. Control takes place.

On the other hand, when the determination in step 106 is YES, the process moves to step 110. In step 110, similarly to the process in step 108, 2 is taken in from the ROM 60 as the attenuation rate based on the detection method of the intake temperature C/I2, and the initial value WL calculated in step 102 is set as WL k,
Set a new initial value. In step 110, as in the process of step 108, the fuel injection time of the injector 24 is set to the ratio of the initial value attenuation amount of the fuel injection amount.
It is determined in accordance with Therefore, after the processing in step 110, based on the attenuation rate of 2, the W period value of the fuel injection amount set in step 102 is set to the fuel injection amount that gradually decreases to the basic fuel injection amount according to the accumulation of engine rotations. 10
is controlled.

As described above, in this embodiment, the ratio of the initial value attenuation amount of the fuel injection amount is set as the attenuation rate that increases as the intake air temperature rises over the engine temperature change range from low temperature to room temperature. When the initial value of the fuel injection amount for increasing the amount of fuel when the engine is cold is set in advance, the initial value of the fuel injection amount is set to the engine based on the attenuation rate according to the intake air temperature. Since the fuel injection amount is gradually reduced to the basic fuel injection amount according to the cumulative rotation, even if the amount of fuel is increased at room temperature, emissions will not increase.
Furthermore, deterioration of drivability at low temperatures can be prevented.

〔Effect of the invention〕

As explained above, according to the present invention, the ratio of the initial value attenuation amount of the fuel injection amount is set in advance as a attenuation rate that increases as the intake air temperature rises over the temperature change range when the engine is cold. When the initial value of the fuel injection amount for increasing the amount of fuel when the engine is cold is set, the intake air temperature is detected, and the set fuel The initial value of the injection amount is gradually reduced to the basic fuel injection amount according to the accumulation of engine rotations, and the fuel amount is increased less at room temperature and more at low temperature, so that the increase in emissions at room temperature is reduced. This has the excellent effect of improving drivability at low temperatures without causing damage.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a system to which the present invention is applied, Figure 2 is a diagram showing the relationship between engine water temperature and W period value of fuel injection amount, and Figure 3 is a diagram showing the relationship between intake air temperature and reduction rate. FIG. 4 is a flowchart for explaining the operation when the present invention is applied to the system of FIG. 1. 10... Engine 12... Intake temperature sensor,
14... Air flow meter, 16... Throttle position sensor, 24... Injector, 38... Water temperature sensor, 44... Rotation sensor, 46... Ignition switch, 50... Control device. Agent Tatsuyuki Unuma (and 2 others) Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] fil Calculate the basic fuel injection amount from the intake air when the engine is cold, correct the calculated basic fuel injection amount based on the engine water temperature, and calculate the 0-stage value of the fuel injection lid as a fuel increase that exceeds the fuel injection amount. A fuel injection amount control method for an internal combustion engine, in which the set zero-stage value is gradually reduced to a basic fuel injection amount according to the accumulation of engine rotation, and fuel is injected at an injection amount corresponding to the decrease in the initial value. In this step, the ratio of the initial value attenuation amount of the fuel injection lid is predetermined as a damping rate that increases as the intake air temperature rises over a temperature change range when the engine is cold, and the initial value of the fuel injection lid is determined in advance. is set, the intake air temperature is detected, and based on the attenuation rate according to this intake air temperature, the initial value of the set fuel injection amount is gradually reduced to the basic fuel injection amount according to the cumulative engine rotation. A fuel injection amount control method for an internal combustion engine, characterized in that: