JPS6388245A - Air-fuel ratio control device - Google Patents

Abstract

PURPOSE:To enable an accurate control of air-fuel ratio to be continually performed, by correcting a change of the output characteristic due to a stain of a hot wire in a hot-wire (HW) sensor, in the case of an electronically controlled fuel-injection engine. CONSTITUTION:On the basis of output voltage from a hot-wire (HW) sensor 10, a change of the output characteristic due to a stain of the HW sensor corresponding to an integrated intake air amount SIGMAQa is corrected through the action via each step of an intake air amount calculating means 22, intake air amount integrating means 23, HW output correction amount calculating means 24 and an HW output correcting means 21. The basic fuel injection quantity Tp is obtained on the basis of an intake air amount Qa, obtained by this corrected HW sensor output, and an engine speed Ne. In addition to the above, various corrections are performed, and an engine, in which a fuel injection amount Ti is determined by a fuel injection quantity calculating means 28, drives an injector 6 by a corresponding injection pulse. Thus a fuel amount is injected so as to continually obtain the optimum air-fuel ratio even if the engine is driven in operation continuing for a long time.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides an air-fuel ratio control device for an electronic fuel injection engine equipped with a hot wire air flow sensor.
It is something to do.

[Conventional technology]

FIG. 3 is a diagram showing the configuration of a general electronic engine control device. In the figure, 1 is a cylinder, 2 is a piston, 3 is an intake air passage, 4 is an exhaust gas passage, 5 is a throttle valve, and 6 is a piston. Injector, 7 is a spark plug, 8 is a wire distributor, 9 is an ignition coil, 10 is a hot wire type air flow sensor (hereinafter referred to as HW sensor), 11 is a throttle opening sensor, 12 is an intake pressure sensor, 13 is an A water temperature sensor that detects the temperature of engine cooling water, 14 a crank angle sensor, 15 an 02 sensor, 19 an HW burn-off voltage generation circuit for burning off dust etc. adhering to the hot wire of the HW sensor 10, and 20 a microcomputer. Each shows an engine υ3111 device consisting of: In the k84 configuration as described above, the engine control device 20
determines the intake air amount Qa based on the output voltage from the HW sensor 10, determines the engine rotation speed Ne based on the signal from the crank angle sensor 14, and determines the basic fuel injection ff1.
Calculate Tp in the form Tp = -Qa /Ne. This calculated basic fuel injection temperature Tp is corrected using water temperature data detected by the water temperature sensor 13, and when acceleration is determined from the signal of the throttle 1771 degree sensor 11, corrections are made such as adding an acceleration increase. , further performs feedback correction based on the signal of the Ox sensor 15 to determine the fuel injection ITi, and drives the injector 6 with the corresponding injection pulse to inject the amount of fuel into the cylinder 1 to achieve the optimum air-fuel ratio. supply Further, the engine control I device 20 determines the optimum ignition time based on the intake air amount Qa, the engine speed Ne, etc., and selects the ignition coil 9. Ignition is provided via the power distribution 389 spark plug 7. Here, the HW sensor 10 that detects the intake air ff1Qa is arranged in the airflow where the hot wire incorporated in the Wheatstone bridge flows through the intake air passage 3, so that dust, etc. that are inhaled together with the intake air are on the surface of the hot wire. As a result, the heat radiation effect of the hot wire on the air flow is reduced, and the output value for the same amount of air changes. For this reason, the engine control device 20 determines whether to stop the engine (step 8), as shown in the flow diagram of FIG.
207), outputs a burnout command to the HW burnout voltage generation circuit 19, and causes the voltage necessary for burnout to be applied from the l-IW burnout voltage generation circuit 19 to the hot wire of the HW sensor 10 for a predetermined period of time. Burn off any dust, etc. that exists (Step 820B)
,) The output characteristics of the IW sensor 10 are restored to normal so that good air-fuel ratio control can be performed.

[Problems to be solved by the invention]

However, the conventional air-fuel ratio control device as described above is
Since the dust adhering to the hot wire surface of the W sensor 10 was removed by burning it off when the engine was stopped and normal output characteristics were restored, the HW
Good air-fuel ratio control can be achieved with the normal output characteristics of the sensor 10, but if the engine is operated continuously for a long time, dust etc. will gradually adhere to the hot wire of the HW sensor 10 by the time the engine is stopped next time, causing the output to decrease. A deviation in characteristics occurs, making it impossible to correctly determine the intake air amount Qa. For this reason, there have been problems such as air-fuel ratio control not being able to be performed satisfactorily, and deviation from the optimum ignition timing occurring, resulting in a decrease in output. In addition, in order to compensate for such deviations in output characteristics,
This can be done using learning control or the like, but there are problems in that it is difficult to make a sufficient correction and the control system becomes complicated. This invention was made in order to solve the above-mentioned problems, and is an air-fuel ratio R1 control device that corrects changes in output characteristics due to contamination of hot wires of the HW sensor and always maintains an appropriate air-fuel ratio i160. The purpose is to provide

[Means to solve the problem]

In order to achieve the above object, the present invention provides an electronically controlled fuel injection engine equipped with a HW sensor.
an intake air amount integrating means for integrating the intake air amount measured by the sensor; and an HW output correction amount calculation means for correcting the output from the HW sensor based on the integrated intake air amount from the intake air amount integrating means; When a burn-off command for the HW sensor is output under predetermined conditions, the HW burn-off command means provides a snow reset signal to the intake air amount integrating means, and a correction value from the f-IW output correction output means is used. A fuel injection amount calculation means for calculating the fuel injection tA suspension based on the corrected output from the above-mentioned HW sensor is provided.

[This is composed of [Function 1] In the air-fuel ratio control 2'lI device of this invention,]-1
Intake air ff1Qa is obtained from the output voltage from the W sensor, this intake air ff1Qa is integrated by an intake air amount integrating means, and H corresponding to this integrated intake air amount ΣQa is calculated.
In order to correct fluctuations in the output characteristics due to dirt on the Wt7 sensor, the integral intake air amount ΣQ is calculated in the HW output correction hanging calculation means.
A correction value corresponding to a is determined, and the output from the HW sensor is corrected using this correction value. A basic fuel injection amount is determined based on the intake air amount Qa and the engine rotation speed Ne based on the corrected HW sensor output, and various corrections are made to this to extract the fuel injection amount. , the HW burn-off command means outputs a burn-off command to the 1-+W burn-off voltage generation circuit under predetermined conditions, and also provides a reset signal to the intake air amount integrating means to reset ΣQa to zero for the integrated intake air. Then, a new integration is started. [Example] Figures 1 and 2 show an example of the present invention.
The figure is a block diagram showing the configuration of the engine control WJ device.
The figure is a flow chart diagram showing the operation of the present invention. Further, the same parts as the conventional example shown in FIG.
9 is the same as that shown in the conventional example. Reference numeral 20 indicates an engine control system (1) consisting of a microcomputer.
1fff, the details of which are shown in FIG. In the figure, reference numeral 21 indicates HW output correction means for correcting the output from the HW sensor 10, 22 indicates an intake air amount calculation means for calculating the intake air IQa from the output voltage from the HW sensor 10, and 2
3 is an intake air amount integrating means for integrating the intake air amount Qa;
4 is an HW output correction amount calculation stage that calculates the correction amount of the output of the HW sensor 10 according to the integral intake air amount ΣQa; 25 is a HW output correction amount calculation stage that generates a HW burn-off command under predetermined conditions, and also sends a reset signal to the intake air amount. I-(W burn-off command means given to the integrating means 23; 26 is an engine speed calculation means for calculating the engine speed Ne based on the input from the crank angle sensor 14; 27 is a basic fuel injection amount calculation means; 28 is a fuel Reference numeral 29 indicates an injection amount calculation means, and 29 indicates an ignition timing calculation means.Next, the operation of the air-fuel ratio control device of the present invention configured as described above will be described with reference to 70-1 in FIG. First, the engine control I device 20 connects the HW sensor 10
．． Crank angle sensor 14. Various data from the water temperature sensor 13, throttle opening sensor 11.
Find f1Qa (step 8101). Here, the flow is divided into an HW output correction routine starting from step 3102, which is the gist of the present invention, and a normal fuel injection control routine. That is, the HW sensor 10 inquires whether or not the burnout has been performed (step 3102), and if the burnout is not performed at that point, the intake air ff1Qa is integrated by the intake air amount integrating means 23 and the integral intake air amount ΣQa is determined. It is squeezed out (step 3103). Then, at the HW output correction interval calculation stage f 24, the integral intake air amount ΣQa, that is, l-
(Step 8104) to extract the HW output corrector according to the fluctuation of the output characteristics due to the contamination of the hot wire of the IW sensor 10)
The HW output correction calculation means 21 corrects the output of the HW sensor 10 based on this HW output correction amount, and the intake air amount calculation means 22 calculates a more correct intake air f! ! Calculate Qa. The HW burn-off command means 25 issues a burn-off command to the HW.
A predetermined burnout voltage is applied to the burnout voltage generating means 19 to generate H.
Application is applied to the hot wire of the W sensor 10 to burn off and remove attached dust, etc., and the output characteristics of the HW sensor 10 are normalized to 1 g.
Let me go home. On the other hand, when the burnout is performed in step Δ102, the HW burnout command means 25 gives a reset signal to the intake air amount integrating means 23 at the same time as the burnout command is generated (step 310
5), the integrated intake air amount ΣQa j
! i: Reset to zero, start a new integration of the intake air ff1Qa due to the continued operation, and correct the output of the HW sensor 10 in accordance with the increase in the integrated intake air amount ΣQa. The more accurate intake air 1alQa obtained in this way is used together with the engine speed Ne calculated by the engine speed calculation means 26 based on the signal from the angle sensor 14 (step 5IIO), as well as the basic fuel injection fPjap output means 27.
The basic fuel injection amount Tp is measured here (
Step 5111), this calculated basic fuel injection ft
1tTp is calculated by the fuel injection amount calculating means 28, including cold/warm correction by the water temperature sensor 4J-13, acceleration increase correction determined by the signal of the throttle opening sensor 11, feedback correction based on the output of the Oz sensor 15, etc. Various corrections are made (step 3N2), and fuel injection ff1Ti
Once determined (Step 5113), the injector is driven by the corresponding injection pulse to inject the amount of fuel that will always provide the optimum air-fuel ratio (Step 5114). In the above steps, the engine is stopped (step 31
15) is repeated. When the engine is stopped, the HW
Burning is performed (step 8116). Although not shown in the flowchart shown in FIG. 2, the engine control device 20 controls the calculated intake air ff.
Ignition time y! based on 1Qa and engine speed Ne! I
] In the calculating means 29, the optimum ignition timing is determined by map search, etc., and the ignition coil 9 is operated at the ignition timing,
Ignition occurs via the power distributor 82 and the spark plug 7 to maintain the engine output at an optimal level.

【Effect of the invention】

As explained above, the air-fuel ratio control device of the present invention has H
The intake air amount determined based on the output from the W sensor is integrated, and the output of the H'W sensor is corrected by the IW output correction amount that is a function of this integrated intake air amount. It is possible to appropriately correct changes in the output of the HW sensor caused by In addition, since the output characteristics of the HW sensor can be synchronously normalized for the above 1-IW output correction dispute, more appropriate correction is possible, and even if the engine is operated continuously for a long time, the Fluctuations in fuel ratio can be effectively prevented.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 show one embodiment of the present invention.
Figure 2 is a block diagram of the engine control a'oia, Figure 2 is a flow chart showing the operation of the present invention, Figure 3 is a block diagram of a general electronic engine control device, and Figure 4 is a flow chart of a conventional example. It is. 6... Injector, 7... Spark plug, 10...
・HW sensor, 14... Crank angle sensor, 19...
・HW burnout voltage generation circuit, 20...Engine IIJ
Go! Device, 21... HW output correction means, 22... Intake air fit7 output means, 23... Intake air amount integration means, 24... HW output correction amount calculation means, 25... HW
Burnout command means, 27... basic fuel injection amount calculation means,
29...Ignition timing calculation means.

Claims (1)

[Scope of Claims] An electronically controlled fuel injection engine equipped with a hot wire air flow sensor, comprising an intake air amount integrating means for integrating an intake air amount measured by the hot wire air flow sensor; HW output correction amount calculation means for correcting the output from the hot wire type air flow sensor based on the integrated intake air amount from the intake air amount integrating means; and a burnout command for the hot wire type air flow sensor under predetermined conditions. When outputting , the HW burn-off command means gives a zero reset signal to the intake air amount integrating means, and the output from the hot wire air flow sensor is corrected by the correction value from the HW output correction amount calculation means. 1. An air-fuel ratio control device comprising: fuel injection amount calculation means for calculating a fuel injection amount based on the fuel injection amount.