JPH04203440A - Fuel injection control device - Google Patents

Abstract

PURPOSE:To most suitably control the correction of abnormal increase in combustion speed, exhaust temperature and the like over the whole range of change in intake air temperature by constituting an intake air temperature correction factor to be set in response to the condition of actual combustion when intake air is changed in temperature. CONSTITUTION:The fuel injection pulse width is operated by an operating section 12 based on the basic injection pulse width and a correction factor in response to each running condition and engine conditions, and based on an intake air temperature correction factor in response to environmental conditions at the time of running with an engine driven, so that fuel injection is thereby controlled. In this case, the actual absolute pressure of an intake pipe when intake air is changed in temperature and a value firmly correlated with combustion speed owing to the basic injection pulse width are determined by a computing section 18, and the intake air temperature correction factor in the output area is set by a setting section 19 in response to the case of actual running based on the aforesaid value firmly correlated with combustion speed. And based on the newly set correction factor, fuel is increased/decreased so as to be corrected, so that optimum correction control is thereby performed at all times.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel injection control device that electronically controls the amount of fuel injected from an injector in a vehicle engine. Regarding the setting of the correction coefficient.

[Conventional technology]

Generally, this type of fuel injection control device is
The fuel injection pulse width is calculated by adding a correction coefficient according to various driving conditions, engine status, etc. to the basic injection pulse width corresponding to the intake air amount per engine, and fuel injection is controlled based on this injection pulse width. It looks like this. Incidentally, vehicles are sometimes used under severe conditions in which environmental conditions such as intake air temperature and atmospheric pressure change relatively significantly, or where the intake air is forcibly cooled by an ink cooler or the like. In this case, for example, it is known that fluctuations in intake air temperature greatly affect the pressure in the intake pipe, the amount of intake air, and the combustion state of the mixture. Therefore, especially when considering the usage environment as described above, It is desirable to correct the fuel injection amount to a fixed amount i based on the intake air temperature and the like.

Conventionally, regarding correction of the intake air temperature of the fuel injection control device, there is a prior art, for example, disclosed in Japanese Patent Application Laid-open No. 7945/1983. Here, in a control system that controls injection by determining the fuel supply area and fuel cut area based on factors such as throttle opening and engine speed, when the intake air temperature is high, the cut area is expanded, and when the intake air temperature is low, 1 increases the supply area. It is shown that the image is corrected to enlarge the image.

[Problem to be solved by the invention]

By the way, in the prior art described above, fuel cut is promoted by considering the quality of combustion depending on the intake air temperature, and for this reason, the fuel injection amount is quantitatively determined with respect to the intake air temperature in the output range due to fuel supply. cannot be corrected. That is, there are problems such as insufficient correction of fuel injection for intake air temperature.

The present invention has been made in view of this point, and its purpose is to quantitatively correct the fuel injection amount in the power range with respect to the intake air temperature, thereby improving the engine output.

An object of the present invention is to provide a fuel injection control device that can improve fuel efficiency and the like.

[Means to solve the problem]

In order to achieve the above object, the fuel injection control device of the present invention has a fuel injection control system that calculates the fuel injection pulse width using the basic injection pulse width and various correction coefficients, and uses the actual intake pipe absolute value when the intake air temperature changes. Pressure.

A means for calculating a value that has a strong correlation with the combustion speed based on the basic injection pulse width, a means for setting an intake temperature correction coefficient according to at least a value that has a strong correlation with the combustion speed, and this intake temperature correction coefficient is also added. and means for calculating the fuel injection pulse width.

[For production]

Based on the above configuration, when driving with the engine running, fuel injection is controlled by calculating the fuel injection pulse width using the basic injection pulse width, a correction coefficient according to each driving condition and engine state, and an intake temperature correction coefficient according to environmental conditions. Ru. At this time, a value that has a strong correlation with the combustion speed is determined using the actual intake pipe absolute pressure and the basic injection pulse width when the intake air temperature changes, and the intake temperature correction coefficient for the power range is determined from the value that has a strong correlation with the combustion speed. , is set in accordance with the actual driving situation, and based on this setting, the amount of fuel is corrected to increase or decrease, so that the correction control is always performed optimally.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, an electronic ! The IJaII system will be described. First, a hot wire air flow meter (1) is installed in the engine's intake system to measure the intake air mass flow rate, an engine speed sensor (2) is installed in the engine's exhaust system to measure the air-to-air ratio based on the oxygen concentration. 02 sensor that detects 3. It further includes a water temperature sensor 4, an accelerator switch 5, a pressure sensor 6 for detecting the absolute □ pressure of the suction pipe, and the like. Signals from these sensors and the like are input to the control unit 10 and processed.

Therefore, regarding the fuel injection control system, the control unit IO has a basic injection pulse width setting section 11 into which the intake air mass flow rate Q from the air flow meter 1 and the engine speed N from the engine speed sensor 2 are input. , the basic injection pulse width Tp is calculated and determined by Tp-K·(Q/N). Here, K is a constant (unit: IIs/g) that converts the intake air quality j1M into an injector injection width equivalent to stoichiometry. And this basic injection pulse width T
p is input to the fuel injection pulse width calculation section I2.

Further, the sudden ratio signal from the 02 sensor 3 is transmitted to the air ratio determination unit 1.
3 to determine whether the air-to-air ratio is rich or lean, and input p and r values corresponding to this into the feedback coefficient setting section 14. On the other hand, it has a feedback condition determining section 15 into which the water temperature Tv from the water temperature sensor 4 and the engine rotation speed N are input, and based on these elements, the 02 sensor 3. It is determined whether or not sudden ratio feedback control conditions are met due to activation of the catalytic converter. Therefore, feedback coefficient setting M1
4, when the feedback condition is satisfied, the learning control unit 1
The feedback coefficient λ is set by searching the map No. 6 according to the determination result of the air-to-air ratio determining section 13 and inputting it to the fuel injection pulse width calculating section 12. Here, the learning control unit 16 learns to sequentially take in the feedback coefficient λ under each engine operating condition based on the engine speed N and the basic injection pulse width Tp, and sequentially update the λ value according to the set frequency.

Furthermore, it has a fuel cut condition determining section 17 in which the engine rotation speed N, water temperature Tw, and accelerator switch signal are manually input, and it is determined whether the fuel cut condition is met if the engine rotation speed is a predetermined engine speed or more during deceleration after warming up. do. Further, the water temperature Tw is input to the water temperature correction coefficient setting section 20, and a correction coefficient KTW corresponding to the water temperature Tw is set.The signal of this fuel cut and water temperature correction coefficient is input to the fuel injection pulse width calculation section 12.

Next, correction measures for intake air temperature will be described.

This intake air temperature correction takes into consideration the changes in the actual intake pipe absolute pressure and intake air mass flow rate with respect to changes in intake air temperature.
This determines a value that has a strong correlation with the actual air-fuel mixture combustion state in the combustion chamber, that is, the combustion speed. Then, the intake temperature correction coefficient is set based on the value that has a strong correlation with this combustion speed,
Under conditions where the value that has a strong correlation with the combustion speed at high temperatures is large, the amount of fuel is corrected to increase the output, and under conditions where the value that has a strong correlation with the combustion speed at low temperatures is small, the amount of fuel is corrected and reduced to improve fuel efficiency. ing.

First, the basic principle of ignition timing control of the present invention will be explained. In an engine, assuming that the volumetric efficiency is constant,
Intake pipe absolute pressure P, displacement per cylinder V, intake air temperature T
, intake mass M, and gas constant R1 volumetric efficiency ηV, the following equation is established from the gas state equation.

P-■・ηv-M-R-T Here, if ηV≠1, P-v≠M-R-T,', P-(M/V)・R-T Here (M/V) is the intake air density, and the basic fuel injection amount T
It is a value proportional to p and filling efficiency. Therefore, the state of advance or retardation of the ignition timing will be considered under various operating conditions.

First, under the condition that the intake air temperature T is constant, the intake air density (M/V
) decreases, the combustion speed slows down, so it is necessary to advance the angle.

Under conditions where the intake air density (M/l) is constant, it is necessary to advance the combustion speed as the intake air temperature T decreases because the combustion rate slows down.Furthermore, under conditions where the intake pipe absolute pressure P is constant, the combustion rate must be advanced as the intake air temperature T decreases. On the other hand, the intake air density (M/V) increases and acts in the direction of canceling it out, but the influence of the intake air temperature T becomes larger.

Furthermore, although it is known that the combustion rate changes exponentially with respect to the intake air temperature T, the temperature range used under actual operating conditions is not so large.

Therefore, if the reference value To for the intake air temperature is set from the combustion reaction rate of the fuel used, the value χ that has a strong correlation with the combustion rate can be approximated as follows.

xoc (M/V) ・ (T-To)CK: (M
/V)-(PV/MR-To)a:P/R-(M/V)
・T.

OCC-P - (M/V) (C two constants, C-1/ToR) From this, the value χ, which has a strong correlation with the combustion rate, is the intake pipe absolute pressure P that changes depending on the intake air temperature T, Intake density (
It can be seen that it can also be expressed as a function of the basic fuel injection amount Tp corresponding to M/V).

Therefore, by setting the intake air temperature correction coefficient KTA using a map of the value χ, which has a strong correlation with the combustion speed, and the engine speed N according to each operating state, it is possible to constantly correct the fuel injection amount quantitatively. It will be possible.

Based on the technical idea, the calculation unit 18 has a value that has a strong correlation with the combustion rate inputted by the intake pipe absolute pressure P of the pressure sensor 6 and the basic injection pulse width Tp, and calculates the value χ that has a strong correlation with the combustion rate. P using the above formula.

Calculated by subtracting Tp. The value χ and the engine speed N, which have a strong correlation with the combustion speed, are input to the intake temperature correction coefficient setting section 19 to set the intake temperature correction coefficient KTA.

Here, the intake air temperature correction coefficient KTA is given by a two-dimensional map of a value χ that has a strong correlation with the combustion rate and the engine rotational speed N depending on each operating state, as shown in FIG. 2(a). That is, as shown in (b) and (c) in the same figure, the correction coefficient KTA is
It is set as an increasing function for both the engine rotation speed N and the value χ that has a strong correlation with the combustion speed.

In this way, when the intake pipe absolute pressure P increases to ΔP when the intake air temperature rises, and the basic injection pulse width Tp decreases to -ΔTp due to air expansion, the value χ that has a strong correlation with the combustion rate becomes +(ΔP
+ΔTp), and this fractional positive coefficient KTA becomes larger. In addition, when the intake air temperature decreases, the intake pipe absolute pressure
P and the basic injection pulse width Tp becomes ΔT due to air contraction.
As p increases, the value χ, which is strongly correlated with the burning rate, becomes −(
ΔP+ΔTp), and this fractional positive coefficient KTA becomes smaller. Then, such an intake air temperature correction coefficient KT
A is also manually input to the fuel injection pulse width calculation section 12.

The fuel injection pulse width calculation unit 12 calculates the basic injection pulse width Tp.
, feedback coefficient λ, fuel cut coefficient NFC, water temperature correction coefficient KTW, intake air temperature correction coefficient KTA, etc.
The fuel injection pulse width TI is calculated as follows.

Ti-Tp・λφKFC x (1+KTW+KTA...)+TsTs: Voltage correction Then, the injection signal with this fuel injection pulse width Ti is output to the injector 7 via the drive circuit 21, and the injector 7
The valve is opened to perform a predetermined fuel injection.

Next, the operation of this embodiment will be described.

First, when driving by engine operation, the control unit I
The fuel injection control system of O includes the intake air mass flow rate Q from the air flow meter 1, the engine rotation speed N from the engine rotation speed sensor 2, the air-to-air ratio signal from the sensor 3, and the water temperature Tv from the water temperature sensor 4.

Input the suction pipe absolute pressure P from the pressure sensor 6, etc.

Then, the control unit 10 determines the basic injection pulse width Tp.

A feedback coefficient λ and a water temperature correction coefficient KTW are set, and it is further determined whether a fuel cut is to be performed.

In addition, the control unit 10 calculates a value χ that has a strong correlation with the combustion rate from the actual intake pipe absolute pressure P and the basic injection pulse width ``rp'' when the intake air temperature changes, and calculates a value χ that has a strong correlation with the combustion rate. An intake air temperature correction coefficient KTA adapted to the combustion state of each operating state is set at the engine speed N and A signal is output to the injector 7 to inject fuel.

Here, especially when the intake air temperature T rises, the correction coefficient K is adjusted to the speed χ, which has a strong correlation with the actual combustion speed.
The value of TA increases, and the amount of fuel is corrected to increase. Therefore, the increased amount of fuel is always completely combusted and the fuel is effectively compensated, and the engine output is accordingly increased. On the other hand, when the intake air temperature T decreases, the value of the correction coefficient KTA decreases in response to the delay in the value χ, which has a strong correlation with the actual combustion rate, and the fuel is corrected to decrease. Fuel efficiency will be improved.

In this way, fuel injection is optimally controlled according to each running condition, engine state, and environmental condition, and the air-air ratio of the air-fuel mixture is always appropriately controlled.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto.

〔Effect of the invention〕

As explained above, according to the present invention, in the fuel injection control system that takes the intake air temperature into consideration, the intake air temperature correction coefficient is set according to the actual combustion state when the intake air temperature changes. It is possible to optimally correct and control abnormal rises in air temperature and exhaust gas temperature over the entire range of changes in intake air temperature.

The combustion state is calculated from the change in the actual intake pipe absolute pressure and basic injection pulse width when the intake air temperature changes, and the intake temperature correction coefficient is set according to this combustion state, so it can be adjusted to suit actual driving conditions. Correction coefficients can be set optimally.

Since the fuel injection amount in the power range is appropriately corrected according to the intake air temperature, the power and fuel efficiency can be effectively improved, and the engine performance can be fully demonstrated in harsh usage environments.

The intake air temperature correction coefficient can be easily and appropriately set using a map of engine speed and a value that has a strong correlation with the combustion speed, and control is also easy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an electronic control system according to an embodiment of the fuel injection control device of the present invention, FIG. 2(a) is a diagram showing a setting map of the intake temperature correction coefficient,
(b) is a diagram showing the relationship between the intake temperature correction coefficient and the engine speed, and (C) is a diagram showing the relationship between the intake temperature correction coefficient and a value that has a strong correlation with the combustion speed. 6...Pressure sensor, IO...control unit, 11...
・Basic injection pulse width calculation section, ■2.. Fuel injection pulse width calculation section, 18.. Calculation section for a value having a strong correlation with the combustion rate, 19.. Intake temperature correction coefficient setting section.

Claims (3)

[Claims] (1) In a fuel injection control system that calculates the fuel injection pulse width using the basic injection pulse width and various correction coefficients, a strong correlation with the combustion rate is established based on the actual intake pipe absolute pressure and the basic injection pulse width when the intake air temperature changes. means for calculating a value having a strong correlation with at least the combustion speed, means for setting an intake temperature correction coefficient according to a value having a strong correlation with at least this combustion speed, and means for calculating a fuel injection pulse width by also adding this intake temperature correction coefficient; A fuel injection control device comprising: (2) The fuel injection control device according to claim 1, wherein the value having a strong correlation with the combustion rate is calculated by subtracting the actual intake pipe absolute pressure and the basic injection pulse width. (3) The fuel injection control device according to claim 1, wherein the intake air temperature correction coefficient is set using a map of a value having a strong correlation with the combustion speed and the engine rotation speed.