JP2518250B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention is directed to A / F (air heat ratio) according to the output from an O ₂ sensor.
The present invention relates to an electronically controlled fuel injection device which performs field back control.

(Prior Art) An electronically controlled fuel injection device is being considered in which the air-fuel ratio A / F is field-back controlled according to the output from the O ₂ sensor. In such an electronically controlled fuel injection device, O ₂
Air-fuel ratio A / F by the sensor Use the average value of the integrated values during field back as the air-fuel ratio A / F learning correction value to cancel the differences in the fuel system, and make the air-fuel ratio A / F close to an appropriate air-fuel ratio. I have to.

(Problems to be solved by the invention) As described above, in the fuel injection control having the learning function to bring the air-fuel ratio A / F close to the stoichiometric air-fuel ratio, when the learning function is reflected even when the engine is fully opened, In consideration of the case where wrong learning is performed, there are the following problems.

Even if the air-fuel ratio A / F is erroneously controlled to the rich side, the fuel consumption is deteriorated and the torque is slightly decreased.However, if the air-fuel ratio A / F is erroneously controlled to the lean side, knocking or The engine may be destroyed due to the rise in exhaust gas temperature.

The present invention has been made in view of the above points, and an object thereof is an electronically controlled fuel injection device in which the air-fuel ratio A / F is field-backed according to the output from the O ₂ sensor for learning control. An object of the present invention is to provide an electronically controlled fuel injection device that makes it possible to perform learning of the air-fuel ratio A / F at the time of full opening only when it is on the rich side.

[Configuration of Invention] (Means and Actions for Solving Problems) Field feedback to the lean side when the air-fuel ratio is on the rich side, and feedback to the rich side when the air-fuel ratio is on the lean side In a fuel injection device having a function, a full-open detection means for detecting the full opening of the engine and a means for activating the learning function only when the air-fuel ratio is on the rich side when the full opening of the engine is detected by the full-open detection means. It is an electronically controlled fuel injection device provided.

With this configuration, the learning function when the engine is fully opened is performed only when the air-fuel ratio is on the rich side.

(Embodiment) An electronically controlled fuel injection device according to an embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11
Is an air flow sensor that detects the amount of intake air sent from an air cleaner (not shown). This air flow sensor
The intake air amount signal a output from 11 is output to the control unit 19 described later. The amount of the intake air is controlled by the throttle valve 12. Further, it is sent to the combustion chamber 15 through the intake valve 14 together with the fuel ejected from the fuel injection valve 13. Then, the exhaust gas discharged from the exhaust valve 16 is discharged to the outside of the vehicle through an exhaust pipe (not shown) after the catalyst 17 removes unnecessary substances.

Further, 18 detects an oxygen excess signal (oxygen concentration signal)
It is an O ₂ sensor. The oxygen concentration signal o output from the O ₂ sensor 18 is output to the control unit 19. Further, the fuel injection valve 13 has the control unit 19
From the injection drive signal i having a pulse width corresponding to the fuel injection amount
Is output. The throttle opening signal t detected by the throttle sensor 12a that detects the opening of the throttle valve 12 is output to the control unit 19.

Reference numeral 20 is a crank angle sensor for detecting the rotation of the crank shaft 21, and the crank angle signal c is output to the control unit 19.

Next, FIG. 2 is a detailed circuit diagram of the control unit 19 of FIG. In the figure, the oxygen concentration signal o and the throttle opening signal t, which are analog signals, are converted into digital data by an A / D converter 31 and output to a CPU (central processing unit) 32. Since the intake air amount signal a and the crank angle signal c are digital signals, CP
Output to U31. The CPU 31 has a learning function regarding the fuel injection amount, and its detailed operation will be described later.
That is, the CPU 31 outputs the injection pulse INJ according to the injection amount of the fuel injected from the fuel injection valve 13. That is, the transistor Q is turned on and the fuel injection valve 13 is operated only during the PULSE period of the injection pulse INJ.

Next, the relationship between the air-heat ratio (A / F) and the engine characteristics will be briefly described with reference to FIG. In FIG. 3, A
Indicates the fuel consumption rate (gr ps · h), B indicates the exhaust temperature (° C), and C indicates the torque (kg · f · m). Further, the theoretical air-fuel ratio when the engine is fully opened is 12.5 indicated by the broken line D in the figure. As is clear from this figure, when the air-heat ratio A / F becomes leaner (that is, the fuel becomes thinner), the fuel consumption rate A increases, so the engine deteriorates due to knocking and the exhaust temperature B also increases.
The torque C also increases, but knocking causes a decrease in torque. In this way, when the air-fuel ratio shifts to the lean side, an unfavorable state occurs for the engine.

On the other hand, the air-fuel ratio is on the rich side (that is, the fuel is richer).
When shifting to, the fuel consumption rate A, the exhaust temperature B, and the torque C all decrease. In this case, the fuel consumption rate A, the exhaust gas temperature B, and the torque C decrease, but knocking does not occur and the exhaust gas temperature also decreases, so the load on the engine is reduced.

Next, the operation of the embodiment of the present invention configured as above will be described. For example, the processing shown in the flowchart of FIG. 4 is performed every 25 ms. First, the oxygen concentration signal output from the O ₂ sensor 18 is converted into digital data by the A / D converter 31 and read into the CPU 32 as the voltage VO ₂ corresponding to the oxygen concentration (step S11). Next, it is determined whether this voltage VO ₂ is larger than 0.4V. Here, when the theoretical air-fuel ratio A / F when the engine is partially loaded is 14.6, the voltage VO ₂
Becomes 0.4V. On the other hand, the theoretical air-fuel ratio A / F when the engine is fully loaded is 12.5.

If it is determined in this step S12 that VO ₂ is greater than 0.4 V, it is determined that it is on the rich side as shown in FIG. 4 (A), and the feedback correction value IFB is subtracted by 0.001 (step S12). S13). That is, the feedback correction value IFB is reduced so that the fuel becomes thinner. On the other hand, if it is determined in step S12 that VO ₂ is 0.4 V or less, it is determined to be on the lean side, and the feedback amount IF
B is incremented by 0.001 (step S14). That is, the feedback correction value IFB is increased so that the fuel becomes richer. Then, it is determined whether or not the feedback correction value IFB is larger than "1" (step S15), and if it is larger, 0.0001 is added to the learning value ISTUDY (step S1).
6) If it is smaller, 0.0001 is subtracted from the learning value ISTUDY (step S17). As described above, when the field back correction value IFB is larger than 1, the air-fuel ratio A / F is on the lean side, so the field back correction value IFB is set to be larger than 1 to make the fuel rich. Above steps
The processing of S11 to S17 is repeated every 25 ms. As a result of repeating this processing, the field back correction value IF
B and the learning value ISTUDY change as shown in FIGS. 6 (B) and 6 (C). That is, the feedback correction value IFB is 1
The learning value ISTUDY changes so as to approach.

Next, the processing of the main routine of the present invention will be described with reference to the flowchart of FIG. First, the intake air amount and the engine speed (rpm) are read by the CPU 32 from the air flow sensor 11 and the crank angle signal (step S2).
1). Next, it is determined whether the engine is fully open (step S22). Here, the determination of whether the engine is fully open is whether the air-heat ratio A / N> α or the manifold absolute pressure MAP>
It is determined from either β or throttle angle> γ. Here, α, β, and γ are constants.

When it is determined in step S22 that the engine is not fully opened, the target air-fuel ratio A / F is set to 14.6 by PUL.
The SE pulse width is determined and the basic injection amount is calculated (step S23). Next, as the pulse width of PULSE, PULSE × IFB
× ISTUDY is calculated (step S24). The operating time of the fuel injection valve 13 is determined based on the calculated PULSE. (Step S25).

On the other hand, in step S22, when it is determined that the engine is fully open, the pulse width of PULSE is determined so that the target air-fuel ratio A / F is 12.5, and the basic injection amount is determined (step S26). . Next, it is determined whether the learning value ISTADY is smaller than 1.0 (step S27). Where the learning value IST
If it is determined that UDY is less than 1.0, that is, if it is on the lean side, the learning function is not performed and the above steps are performed.
The fuel injection process of S25 is performed. On the other hand, the above step S27
If I STUDY is judged to be 1.0 or more, that is, if it is judged to be on the rich side, PULSE pulse width P
ULSE × ISTUDY is calculated. (Step S28). In other words, it is reflected only on the rich side of the learning function when the engine is fully opened.

[Effects of the Invention] As described in detail above, according to the present invention, in the electronically controlled fuel injection device in which the air-fuel ratio A / F is field-backed for learning control according to the output from the O ₂ sensor, the engine is fully opened. Since the learning function of the air-fuel ratio A / F at the time is reflected only when the air-fuel ratio A / F is on the rich side, even if the learning function is operated in the wrong direction, the engine will not deteriorate. It is possible to provide a non-electronically controlled fuel injection device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electronically controlled fuel injection device according to an embodiment of the present invention, FIG. 2 is a partially detailed diagram of FIG. 1, FIG. 3 is an air-fuel ratio-engine characteristic diagram, and FIG. 4 is a timer. FIG. 5 is a flow chart showing the operation of the routine, FIG. 5 is a flow chart showing the operation of one embodiment of the present invention, and FIG. 6 is a diagram showing each output waveform. 11 …… Air flow sensor, 13 …… Fuel injection valve, 18 …… O ₂
Sensor, 19 ... Control unit, 31 ... A / D converter, 32 ... CPU.

Claims (1)

(57) [Claims] 1. A fuel injection device having a learning function of performing field back to the lean side when the air-fuel ratio is on the rich side, and feedback to the rich side when the air-fuel ratio is on the lean side, with the engine fully open. An electronically controlled fuel injection device, comprising: a full-open detection means for detecting that the air-fuel ratio is a rich side when the full-open detection means detects the full-open state of the engine.