JPS63272933A - Control device for fuel injection - Google Patents

Abstract

PURPOSE:To rapidly converge air-fuel ratio at the time of the failure of a sensor to a proper value by outputting a fuel injection pulse width which is operated based on the operating condition of an engine instead of a fuel injection pulse width by moderating control at the normal time, at the time of the failure of an air flow sensor. CONSTITUTION:At the time of operating an engine 1, first, a basic fuel injection time is operated by an ECU 14 based on the outputs of an air flow sensor (AFS) 8 and an engine speed sensor 11. Then, a moderating control is carried out based on the basic fuel injection time, and the time width of a fuel injection pulse signal corresponding to the operating condition of a vehicle at the time of accelerating/decelerating is operated. And, by judging whether the AFS 8 is in failure and, when judged in failure, a fuel injection pulse width at the time of an AFS failure which is operated from the outputs of the engine speed sensor 11 and a throttle opening sensor 12 is read out. This fuel injection pulse width at the time of the AFS failure is corrected based on a correction factor operated in accordance with an intake air temperature and water temperature, etc., to control a fuel injection valve 13 according to the corrected injection pulse width.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a fuel injection control device that controls the fuel injection amount of an engine by electronic control.

[Conventional technology]

For example, when a vehicle such as a car accelerates or decelerates, the air flow sensor (hereinafter referred to as
The amount of intake air detected by the AFS is much larger, and the air-fuel ratio becomes richer. Furthermore, during deceleration, the air-fuel ratio becomes lean due to a phenomenon opposite to the above. The effects of deterioration in drivability due to over-rich during acceleration or over-lean during deceleration are described in, for example, Japanese Patent Application Laid-Open No. 58-25.
It is removed by the sluggish treatment disclosed in Japanese Patent No. 531. The content of this disclosure is that the AFS is used to correct the difference between the intake air amount detected by the AFS and the actual intake air amount of the engine.
The basic fuel injection amount output based on the output signal and engine speed detection signal is rounded, and this rounded value is corrected according to the comparison result with the basic fuel injection amount. The annealed value is used as the limit value of the fuel injection amount.

[Problem that the invention seeks to solve]

Since the conventional fuel injection control device is configured as described above, there are cases where the AFS malfunctions temporarily due to poor contact between the connectors. t, the temporary smoothing value is 0, and if this time the AFS has died down from the failure and is not AFS7, the smoothing value will be 0 immediately after recovery, and from now on, the smoothing value will gradually decrease. As a result of the processing, the pulse width approaches the normal value, but the air-fuel ratio becomes lean immediately after AFS fKi, resulting in unstable engine speed and engine stalling, and engine stalling at idle. There were some problems, such as:

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel injection control device that can quickly stabilize the engine speed even immediately after returning to tM from an AFS failure.

[Means for solving problems]

The fuel injection control device according to the present invention performs smoothing processing, and when the air flow sensor fails, calculates the fuel injection pulse width based on the detection signal of the engine condition of the sensor means excluding the air flow sensor, and calculates the calculated value. A fail calculation means is provided for replacing the value calculated by the smoothing processing means for rounding.

[For production]

In this invention, the fuel injection control device replaces the calculated value of the failure calculation means with the calculated value of the smoothing processing means when the airflow sensor fails, and continues this replacement &I as the smoothing processing immediately after the airflow sensor returns. Therefore, the optimum air-fuel ratio is set immediately after the air flow sensor returns.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a fuel injection control device according to an embodiment of the present invention. In FIG. 1, 1 is a well-known engine installed in, for example, an automobile, 2 is an air cleaner provided on the most upstream side, 3 is an intake pipe, and 4 is provided in the intake pipe 3, including the amount of depression of the accelerator pedal, etc. 5 is an intake manifold for the engine 1 that communicates with the downstream port of the intake pipe 3; 6 is an exhaust manifold for the engine 1; 7 is an exhaust pipe connected to the exhaust manifold 6. It is. This engine 1 takes in air from an intake manifold 5 via an air cleaner 2 and an intake pipe 3, and discharges the air after combustion to the atmosphere from an exhaust manifold 6 via an exhaust pipe 7. 8
is provided in the intake pipe 3 portion upstream of the throttle valve 4,
9 is AFS, which detects the temporary amount of air taken into the engine 1 and generates a pulse signal with a frequency proportional to the intake amount.
This is an intake air sensor that is installed in the 3rd part of the intake pipe near the FS8, detects the temperature AT of the intake air, and outputs an analog signal proportional to the intake air temperature. 10 is engine 1
The warm-up sensor 11 detects the temperature WT of the cooling water of the engine 1, for example, and is a rotation speed sensor that detects the rotation speed N of the crankshaft of the engine 1 and outputs a pulse signal with a frequency corresponding to the rotation speed N.

12 detects the opening degree of the throttle valve 4 and closes the throttle valve 4;
A throttle sensor 13 outputs an analog signal according to the throttle angle θ, and 13 is an electromagnetic fuel injection valve provided for each cylinder of the engine 1.

Reference numeral 14 denotes a read-only memory (hereinafter referred to as ROM) 1 that stores the programs of the flows shown in FIGS. 3 to 5.
The electromagnetic fuel injection valve 13 is an electronic control unit ECU having 4A, and is a circuit that calculates the fuel injection amount etc. based on the detection signals of the AFS 8, intake temperature sensor 9, warm-up sensor 10, rotation speed sensor 11, and throttle sensor 12. The fuel injection amount is adjusted by controlling the valve opening time. 15 is an in-vehicle switch that connects the electronic control device 1 via a key switch 16.
Connected to 4.

The internal configuration of the electronic control device 14 will be explained with reference to FIG. 14A is the above-mentioned ROM, and 14B is a central processing module M (hereinafter referred to as CPU) that calculates the fuel injection amount and the like. 1
4C is a rotational speed counter that counts the engine rotational speed based on a signal from the rotational speed sensor 11. 14
D is an interrupt control unit to which an interrupt command is sent by the revolution counter 14C in synchronization with the engine rotation, and upon receiving this command, outputs an interrupt signal to the CPU 14B via the bus 14E. 14F is a digital input port, which calculates the intake air amount A by counting pulse signals from AFS8.
An intake air amount signal corresponding to the amount is sent to the CPU 14B. 14G is an analog input port consisting of, for example, an analog multiplexer and an A/D converter, which A/D converts each signal from the intake air temperature sensor 9, warm-up sensor 10, and throttle sensor 12, and sequentially reads the signals into the CPU 14B. 14H is CPU1
Random access memory as 4B working memory (
(hereinafter referred to as RAM), 141 is an output circuit, and CPU1
The digital signal of the fuel injection amount calculated by 4B is converted into a pulse signal with a pulse time width that gives the opening time of the electromagnetic fuel injection valve 13, and the electromagnetic fuel injection fp13 is driven. 14J measures the elapsed time with a timer and transmits it to the CPU 14B. Above 14A, 14C to 14D p 14
Each component designated by a symbol F to 14J is connected to a bus 14E.
It is commonly connected to CPU14B. 14 is a power supply circuit that constantizes the voltage of the battery 15 and supplies power to the electronic control unit 14.

Figure 3 shows the main routine executed by the CPU 14B.
5 is a flowchart showing the interrupt processing routine, and FIG. 5 is a flowchart showing the smoothing processing of FIG. 4. The flow shown in FIG. 5 is the same as the conventional flow. Figure 6 shows
From the engine speed N and throttle angle θ, the basic pulse at the time of AFS failure 'II wA, F outputt t h
Each set of (N, e, WA, .) is stored in the ROM 14A in advance in the form of a matrix.

Next, the operation will be explained.

When the upper key switch 6 is turned on, the power of the battery 15 is turned on to the power supply circuit 14K, and the arithmetic processing of the main routine shown in FIG. 3 is started. It is initialized in step S1, and various engine parameters are read and stored in the RAM 14H in step S2. In this step S2, a digital value corresponding to the rotation speed N is input from the rotation speed counter 14C, a digital value corresponding to the intake air amount A is input from the digital input port 14F, and a digital value corresponding to the intake air amount A is input to the analog input port 14.
Digital values corresponding to the intake air temperature AT, the cooling water temperature WT of the engine 1, and the throttle angle θ are sequentially read from G.

In step S3, a fuel correction coefficient K is calculated based on the results of the intake air temperature AT and the cooling water temperature WT, and the results are stored in the RAM 14H.

In the next step S4, it is determined whether or not the intake air amount A has not been detected, that is, whether or not AFS has failed.
(Due to poor contact of S8 terminal) JAFS8 output signal is 0.
If intake air amount A is not detected in
If it is not 0, it is assumed that AFS 8 is not out of order and a negative determination is made as non-AFS fail. This step S
If the determination in step S4 is negative, the process returns to step S2.

If an affirmative determination is made in step S4, AF is performed using the ROM 14A according to the map shown in FIG.
The injection pulse intensities WA and F at the time of 3 failures are calculated and the results are stored in the RAM 14H. After completing step S5, the process returns to step S2. Usually step 82 in Figure 6
The main routine processing of steps S4 to S4 or steps S82 to S5 are repeatedly executed according to the control program.

When an interrupt signal from the interrupt control section 14D is input, even if the main routine is being processed, the processing is interrupted and the processing shifts to the interrupt processing routine shown in FIGS. 4 and 5.

In step 310, a signal representing the engine rotation speed N from the rotation speed counter 4C is read. Next step 311
Now, a signal representing the intake air amount A is read from the digital input port 14F. Next, in step S12, the basic fuel injection amount, that is, the injection time W of the electromagnetic fuel injection valve 13 determined from the engine speed N1, the intake air amount A, and the constant P stored in the ROM 14A in advance, is calculated using the formula w = p. x
Calculate according to Δ.

In the next step 813, the smoothing process shown in FIG. 5 is executed based on the basic fuel injection amount W, and the time period of the fuel injection pulse signal applied to the electromagnetic fuel injection valve 13 according to the driving state of the vehicle, such as acceleration or deceleration, is executed. Calculate and output the width Wi. Next, in step 314, A,
It is determined whether or not there is an FFS fail. If it is not an AFS fail, the process proceeds to step 316. If it is an AFS fail, the RAM has already been stored in step S5 of the main routine.
The fuel injection pulse widths WA and F stored in 14H are replaced with the fuel injection pulse width Wi. The process proceeds from step S15 to step S16, and in step 316, the fuel injection pulse vAWi is corrected using the correction coefficient K already stored in the RAM 14) (in step S3 of the main routine. After this correction, in step 317, the corrected Set the fuel injection pulse width in the counter of the output circuit 141,
Next, in step 318, the main routine returns to the interrupted process.

The corrected fuel injection pulse width set in the counter of the output circuit 14T is converted into a fuel injection pulse signal by the output circuit 14I and applied to the electromagnetic fuel injection valve 13.

Next, details of the smoothing process in step 313 will be explained with reference to FIG. 5. At step 5130, weighted average processing of the basic injection amount W is performed. Here, the arithmetic expression is: Here, J is the constant of the smoothing coefficient, T is the weighted average processing value, W is the basic injection amount, and n is 0, 1°22...2
It is m. When the smoothing coefficient J is relatively large, the smoothing effect becomes large, but when the smoothing coefficient J is relatively small, the smoothing effect becomes small. Next step 5
At step 131, the basic injection amount W and the weighted average processing value T are compared in size.

W) When T is accelerating, the process proceeds to step 5133. When T is a constant speed, the process proceeds to step 5132. (When T is decelerating, the process proceeds to step 5136. In step 5132, the basic injection amount W is directly used as the fuel injection pulse width Wi.

In step 5133, the weighted average processing value T is given a coefficient C''.
Multiply by (C+≧1) to find T' and correct T. In the next step 5134, the basic injection amount W and the corrected weighted average processed value T' are compared, and if W>T', the process proceeds to step 5135, where T' is set as Wi, and if W≦T' tear, step S 132 binary h W e W t.

In step 5131, if W<T, step 513
Proceeding to step 6, T is multiplied by C- (C-≦1) to obtain T' and T is corrected. In the next step 8137, W and T' are compared, and if W<T', the process advances to step 8138 and T
' is set as Wi, and if W≧T', the process advances to step 5132 and W is set as Wi. This concludes the explanation of the smoothing processing routine.

In addition, in the above embodiment, the basic injection pulse width W at the time of AFS failure is determined from the engine speed N and the throttle angle θ.
However, the invention is not limited to this, and the engine intake pressure is detected by a boost sensor that detects the air pressure immediately downstream of the throttle valve 4, and based on this intake pressure and engine rotation speed, the injection pulse width WA at the time of AFS failure, , may be found.

〔Effect of the invention〕

As described above, according to the present invention, the fuel injection pulse width at the time of AFS failure, which is generated based on the parameters detected for the engine state at the time of AFS failure, is replaced with the fuel injection pulse width obtained by the smoothing process when AFS is normal. Because of this configuration, the fuel injection pulse width does not become O when AFS fails, and the engine Rotation is smooth and stable, the engine does not stall or stall, and it has the effect of providing a good driving feeling.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the entire device according to an embodiment of the present invention;
Figure 2 is a detailed configuration diagram of the electronic control unit, etc. Figures 3 to 5 are flow diagrams showing each routine according to an embodiment of the present invention, Figure 6 is an AFS failure diagram with respect to engine speed and throttle angle. FIG. 3 is an explanatory diagram showing a map of the fuel injection amount at the time of the fuel injection. In the figure, 1...engine, 3...ffl'c pipe, 4...
... Throttle valve, 8... AFS, 11... Rotation speed sensor, 12... Throttle sensor, 13... Electromagnetic fuel injection valve, 14... Electronic control unit, 14A... ROM
, 14B... CPU, 14 C... rotation speed sensor,
14D...Interrupt control unit, 14E...Bus, 14F
...Digital input port-1, 14G...Analog input port, 14H...RAM, 141...Output circuit,
14K...power supply circuit, 15...battery. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] an air flow sensor that outputs a signal corresponding to the amount of intake air passing through an intake pipe for intake into the engine; sensor means for detecting each operating state of the engine; and sensor means for detecting each operating state of the engine; smoothing processing means for calculating the time width of the fuel injection pulse signal to be applied to the electromagnetic fuel injection valve for the engine by performing basic fuel injection pulse width smoothing processing based on the output signal of the means;
When it is detected from the output of the air flow sensor that the air flow sensor is in failure, the fuel injection pulse width at the time of failure is calculated based on the output signal of the sensor means other than the air flow sensor, and the calculated value is used as described above. A fuel injection control device comprising a failure calculation means for replacing a value calculated by a correction processing means.