JPS6341644A - Electrification control device for internal combustion engine control device - Google Patents

Abstract

PURPOSE:To enhance the reliability of a device, in which an electric current is passed to an air flowmeter via a relay to burn out the attached substance thereto, by enabling the passage of an electric current to the air flowmeter to be compensated even at the time of relay trouble and further enabling the selfdiagnosis of relay trouble. CONSTITUTION:When an ignition switch 4 is changed over in the state of OFF, the passage of an electric current to a transistor 6 via a diode 5 is cut off, and the passage of an electric current to the transistor 6 continues, for a prescribed time, via a diode 7. Thus, the contact point 8b of a relay 8 is maintained in the state of ON to continue the passage of an electric current to an air flowmeter 11, so that the attached substance attached on a heating wire is burned out. Thereafter, whether or not a prescribed burning-out time has elapsed is judged, and when this time has elapsed, the relay 8 is turned OFF to complete the burning-out operation. Further, in this case, if the contact point 8b is maintained in an open state because of the failure of the relay 8, when an ignition switch 4 is turned ON, a transistor 13 is turned ON to light a warning lamp 14, so that the abnormality of the relay 8 is notified.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a control circuit for an electronically controlled fuel injection device of an internal combustion engine and a device for controlling energization to a hot wire airflow meter.

<Prior art> An overview of this type of conventional device will be explained based on FIG. 3.A battery (power source) 1 and an electronic fuel injection IJ? ffH
Microcomputer 3
The input terminal (for detecting ignition switch ON/OFF) I+ is connected to the input terminal T via the ignition switch 4.

is connected to the base of transistor 6 via diode 5. Further, the output terminal 01 of the microcomputer 3 is connected to the heath of the transistor 6 via a diode 7.

The collector of the transistor 6 is a coil 8a of the relay 8.
The emitter is connected to the battery 1 through the ground.

On the other hand, the normally open contact 8b of the relay 8 is connected to the battery 1.
It is connected to the input terminal I2 of the electric R circuit 9 of the control unit 2 via the input terminal I2, and is also connected to a hot wire air flow meter 11 installed in the intake passage 10 of the engine.

The output terminal 02 of the power supply circuit 9 is connected to the power input terminal 11 of the microcomputer 3.

Let me explain how this works. ignition switch 4
When turned ON, transistor 6 is connected via diode 5.
is turned on, the coil 8a of the relay 8 is energized, and the contact 8
b is closed, power is supplied from the battery 1 to the power supply circuit 9 and the air flow meter 11, and power is supplied from the power supply circuit 9 to the microcomputer 3.

As a result, the diode 7 is connected to the base of the 1-range star from the microcomputer 3 together with the diode 5.
A base current is supplied through.

In this state, the air flow meter 11 controls the current applied to the hot wire according to the intake air flow rate by a control circuit (not shown), and the intake air flow rate is detected based on the current. Further, the microcomputer 3 outputs an injection pulse corresponding to a fuel injection amount calculated according to the intake air flow rate, etc. to a fuel injection valve (not shown), thereby controlling fuel injection.

Next, when the ignition switch 4 is turned OFF, the supply of base current to the transistor 6 via the diode 5 is cut off, but the transistor 6 continues to be energized from the microcomputer 3 via the diode 7 for a predetermined period of time, which causes the relay to The contact 8b of No. 8 is also maintained in the ON state for a predetermined period of time, so that the airflow meter 11 continues to be energized. At this time, a burnout circuit (not shown) of the air flow meter 11 is activated to burn off the deposits attached to the hot wire exposed into the intake passage 10, thereby ensuring normal operation of the air flow meter 11.

<Problems to be Solved by the Invention> In this way, the microcomputer 3 and the air flow meter 11 are energized via the relay 8 in order to continue energizing the hot wire air flow meter 11 for a predetermined period of time even after the ignition switch 4 is turned off. However, if reliability decreases due to the use of the relay 8, and a failure occurs such as when the contact 8b is held open due to disconnection of the coil 8a, etc., the ignition switch 4 may be turned on. Even if the air flow meter 11 and the power supply circuit 9 are turned on, the microcomputer 3 is no longer energized.

The present invention has been made by focusing on such conventional problems, and even if a relay failure as described above occurs, the control circuit and air flow meter are energized to maintain the intake air flow rate. It is an object of the present invention to provide an energization control device for an internal combustion engine control device that can perform detection and control such as fuel injection control based on the detection signal, etc., and can also notify failure of a relay.

<Means for Solving the Problems> For this reason, the present invention has the advantage that when the ignition switch is turned on, power is supplied to the hot wire air flow meter that is installed in the control circuit of the internal combustion engine and the intake passage and detects the intake air flow rate. In the energization control device for an internal combustion engine control device, the energization control device is configured to conduct electricity through a relay that is turned ON, and to burn off deposits on the air flow meter by energizing the air flow meter when the ignition switch is turned OFF. a fail-safe circuit connected to the current through an ignition switch and a diode that allows forward current, and a burn-out determining means for determining whether or not an operation to burn off the deposits on the air flow meter has been performed; a determination result storage means for storing and retaining the determination result by the determination means even after the ignition switch is turned off;
The apparatus is configured to include a reporting means for reporting the presence or absence of an abnormality based on the memory in the storage means when the ignition switch is turned on.

In this configuration, when the relay is normal, the air flow meter and the microcomputer are energized via the relay as in the conventional case.

In addition, if a failure occurs where the relay contacts are held open, turning the ignition switch ON will cause
A fail-safe circuit with a diode energizes the direct control circuit and hot-wire airflow meter.

Furthermore, since a diode is inserted in the fail-safe circuit, it is possible to prevent current from flowing backwards from the fail-safe circuit to the circuit that energizes the relay after the ignition switch is turned off when the relay is in normal condition, so the relay remains in the ON state. You can prevent it from happening again.

In addition, when the relay fails, the burn-out operation is not performed, but this is determined by the burn-out determination means and the determination results are described in 4. 4. Even after the ignition switch is turned off in the a means.
Retain. Next, when the ignition switch is turned on, the relay failure is reported by the reporting means based on the stored information.

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

In FIG. 1 showing one embodiment, all the circuits shown in FIG. 2 are included, and the same reference numerals are given to these components, and the explanation thereof will be omitted.

To explain the part related to the present invention, a diode 12 that allows current to flow between the input terminal 1 of the microcomputer 3 and the input terminal I2 of the power supply circuit 9 from the former to the latter.
Connect via. That is, a fail-safe system in which a control unit (including a crank angle sensor) 21 as a control wholesale circuit and a hot wire air flow meter 11 are connected to a battery (power source) 1 via an ignition switch 4 and a diode 12 that allows forward current. A circuit is provided.

The microcomputer 3 also determines whether or not the air flow meter 11 has been burnt out, stores the determination result in the back amplifier memory, and when the air flow meter 11 has not been burnt out, the next time the ignition switch 4 is Set a control program that sets the output terminal 03 to H level when turned ON.

The base of a transistor 3 is connected to the output terminal 03, and the collector and emitter of the transistor 3 and an alarm lamp 14 are connected to the battery 1 in series.

Next, the action will be explained.

When the ignition switch 4 is turned on when the relay 8 is normal, and for a predetermined time after the ignition switch 4 is turned off, the power supply circuit 9, the power supply circuit, and the aphrometer 1 are energized in the same manner as in the conventional case. Here, when the ignition switch 4 is turned on, the input terminals I and 12 are both equal to the voltage of the battery 1, so the fail-safe circuit consisting of the diode 12 is not energized, and when the air flow meter 1 is burnt out after the ignition switch 4 is turned off, Input terminal I2 is held at battery voltage;
Input terminal 1 is at ground level, but since diode 12 is provided, it is connected to transistor 6 via diode 5.
No base current is supplied to the base, and the 8 is ON.
It is possible to prevent this from continuing even after the burnout is completed.

Also, if the relay 8 fails and the contact 8b is held in the open state, the ignition switch 4. Contact 8b when ON
The power supply to the power supply circuit 9 and the air flow meter 11 is cut off, but the power supply circuit 9 and the air flow meter 11 are energized through the diode 12 and the resistor 13, and the intake air flow rate is detected by the air flow meter 11. The microcomputer 3 can normally control fuel injection, etc. based on the signal.

Next, a routine for self-diagnosing the presence or absence of a failure in the relay 8 and reporting the diagnosis result will be explained with reference to FIG. This routine is started by turning on the ignition switch 4.

In step (denoted as S in the figure) 1, it is determined whether the self-diagnosis flag FNG of the relay 8 is 1 or not. As will be described later, when relay 8 is normal, FNG = 0 in step 6 during the previous operation, so after proceeding to step 2 and setting FNG to 1, various controls such as engine fuel injection are performed. (circuit omitted). Next, in step 3, it is determined whether or not the ignition switch 4 is turned off. If the ignition switch 4 is turned on, the above-mentioned control is continued, but when it is turned off, when the relay 8 is normal, the output terminal 0 is output as described above.
1 becomes H level, and the deposits on the air flow meter 11 are burned off.

Next, in step 5, it is determined whether or not the burn-out time has ended, and when it has ended, the process proceeds to step 6, where FNG is reset to 0, and then the process proceeds to step 7, where the output terminal OI is set to 1.
By setting the level, the relay 8 is turned off and the burn-out operation is stopped.

Here, the FNG value in step 2 and step 6 is determined by the backup memory built into the microcomputer 3.
(Constituting the determination result storage means of the present invention) as described in 4.1, and is stored and retained even after the ignition switch 4 is turned off.

On the other hand, if the relay 8 fails and the contact 8b is held open, the ignition switch 4
When the ignition switch 4 is turned on, it operates as normal due to the fail-safe circuit, but after the ignition switch 4 is turned off, the burnout operation is not performed, so the FNG=1 is set in step 2 without proceeding to step 4 or later. The current state is stored in the backup memory.

Therefore, the next time the ignition switch 4 is turned on, the determination in step 1 is YES, and the process proceeds to step 8, where the output terminal 03 is set to H level, the transistor 13 is turned on, and the alarm lamp 14 is lit. Reports relay abnormalities.

As a result, by knowing the failure of the relay 8 and repairing it, the driver can perform a burnout operation after turning off the ignition switch 4.

In this way, a failure of the relay 8 can be self-diagnosed by setting the flag FNG to 0 or 1 depending on whether or not a burnout operation has been performed, and in the event of a failure, it can be reported by lighting the alarm lamp 14. That is, the functions of step 2 and step 6 in FIG. 2 correspond to a burn-out determination means, and the alarm lamp 14 corresponds to a notification means.

<Effects of the Invention> As explained above, according to the present invention, it is possible to compensate for the energization of the control circuit and air flow meter when the ignition is turned ON in the event of a relay failure, without interfering with the normal operation of the relay. In addition to being able to self-diagnose and report relay failures, it can be implemented at low cost because it only requires the addition of a simple circuit.

is a circuit diagram showing a conventional example.

1...Battery 3...Microcomputer 4
...Ignition switch 5...Diode 6...1-ransistor 7...Diode 8
... Relay 9 ... Power supply circuit 10 ... Intake passage 11 ... Hot wire air flow meter 12 ...
Diode 13...Alarm lamp 21...Control unit Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio SasashimaFigure 1Figure 3Figure 2TART ■"°゛"゛.

NOv graduation history upsu, inucho FNG-I S2 IGNSWON FF

Claims (1)

[Claims] The control circuit of the internal combustion engine and the hot-wire air flow meter that is installed in the intake passage and detects the intake air flow rate are energized via a relay that is turned ON when the ignition switch is turned ON, and after the ignition switch is turned OFF. In the energization control device for an internal combustion engine control device, the relay is held in an ON state by a signal from the control circuit for a predetermined period of time to energize a hot wire air flow meter and burn off deposits on the air flow meter. A fail-safe circuit is provided in which the circuit and the hot-wire air flow meter are connected to a current via an ignition switch and a diode that allows forward current, and it is determined whether or not an operation has been performed to burn off deposits on the air flow meter. a determination result storage means for storing and retaining the determination result by the determination means even after the ignition switch is turned off; and a reporting means for reporting the presence or absence of an abnormality based on the memory of the storage means when the ignition switch is turned on. An energization control device for an internal combustion engine control device, characterized in that: