JP3146850B2 - Engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly to an engine control device for supplying an accurate air flow rate when the internal combustion engine is started.

[0002]

2. Description of the Related Art In the conventional invention, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent Publication No. 217, the heating state at the start of power supply to the air flow meter is detected, and rapid heating is performed to improve the air flow measurement accuracy at the start of power supply.

[0003]

In the above prior art, the time when the measurement of the air flow rate at the start of power supply is not accurate cannot be set to 0 even by rapid heating. there were. Therefore, an object of the present invention is to provide an air flow meter capable of accurately measuring an air flow even at the start of power supply for starting operation of an engine.

[0004] The above object is to directly control the intake air amount of the internal combustion engine.
Or a means for indirectly detecting the amount of intake air directly
Or means for supplying electricity to the means for indirectly detecting,
Direct or indirect intake air flow during internal combustion engine shutdown
Having means for supplying electricity to the means for detecting current
In the control device, when the internal combustion engine is stopped,
Electric power supplied to means for directly or indirectly detecting air volume
The amount is determined directly or indirectly by the amount of intake air during operation of the internal combustion engine.
It is not more than the amount of power supplied to
This is achieved by an engine control system.

[0005]

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection control apparatus for an internal combustion engine using a hot wire air flow meter according to the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 2 shows an example of an engine system to which the present invention is applied. In the figure, air to be taken in by the engine is taken in from an inlet 2 of an air cleaner 1 and a throttle valve for controlling an intake flow rate is accommodated. Throttle body 5
And enter the collector 6. Then, the intake air is distributed to each intake pipe 8 connected to each cylinder of the engine 7 and guided into the cylinder.

On the other hand, fuel such as gasoline is sucked and pressurized from a fuel tank 9 by a fuel pump 10, and then a fuel damper 11, a fuel filter 12, a fuel injection valve (injector) 13, and a fuel pressure regulator 14 are connected to a pipe. Supplied to the fuel system. Then, the fuel is regulated to a constant pressure by the fuel pressure regulator 14 described above,
Fuel is injected into the intake pipe 8 from a fuel injection valve 13 provided in the intake pipe 8 of each cylinder.

A signal representing the intake air flow rate is output from the air flow meter 3 and input to the control unit 15.

Further, a throttle sensor 18 for detecting the opening of the throttle valve is mounted on the throttle valve body 5, and the output thereof is also input to the control unit 15. Next, 16 is a dist (distributor)
A crank angle sensor is built in the dist, and a reference angle signal REF indicating the rotational position of the crankshaft and an angle signal POS for detecting the rotational speed (rotation speed) are output. These signals are also transmitted to the control unit. 15 is input.

Reference numeral 20 denotes an A / F sensor provided in the exhaust pipe, which detects whether the air-fuel ratio is rich or light relative to a desired air-fuel ratio in order to detect the actual operating air-fuel ratio. Is also input to the control unit 15.

As shown in FIG. 3, the main part of the control unit 15 receives as input signals from various sensors for detecting the operating state of the MPU, ROM and A / D converter engine, and executes predetermined arithmetic processing. It executes various control signals calculated as a result of the calculation, supplies predetermined control signals to the fuel injection valve 13 and the ignition coil 17 that have been lifted, and performs fuel supply amount control and ignition timing control. It is.

In the engine of this type, the air flow meter 3
Is required to always accurately measure the air flow rate taken by the engine. However, immediately after the power is supplied to the air flow meter 3 when the engine is started, the internal circuit after power supply is accurate until the internal circuit reaches a steady state. The air flow cannot be measured. For example, in the case of a hot wire air flow meter, the measurement principle is to provide a heating element in the intake passage and to know the air flow rate by detecting the amount of heat taken by the flow of air.
Until the heating element reaches a predetermined temperature, an accurate air flow rate cannot be known. Specifically, the characteristic shown by the solid line in FIG. FIG. 5 is a diagram illustrating an example of characteristics when the power of the air flow meter is turned on when there is no air flow, and the output voltage is an output value obtained by converting the air flow into a voltage. Here, when the power is turned on, electricity is supplied to the air flow meter. However, a large current flows through the heating element during a predetermined time in order to heat the heating element and make the air flow rate detectable. This is equivalent to a phenomenon in which a large amount of heat is deprived from the heating element due to an apparently large air flow rate. Therefore, the output voltage temporarily increases once and then converges toward a true value. This behavior is the same when there is an air flow rate.If the engine is started immediately after the power is turned on, a measurement error will occur in the intake air amount, and the fuel supply will be excessive, making it difficult or impossible to start, or harmful components. The unburned fuel component in the exhaust gas is large.

This phenomenon is caused by heating the heating element of the air flow meter from room temperature. To avoid this phenomenon, the heating element may be kept heated even when the engine is stopped. Therefore, an embodiment of the present invention for avoiding this phenomenon is shown in FIG. The air flow meter 101 includes a battery 1
From 03, electricity is supplied regardless of whether the ignition switch 104 is ON or OFF. Even when the ignition switch 104 is turned off, the heating element of the air flow meter is energized by the supply current from this line, and the temperature is kept higher than the ambient temperature. An engine fuel injection control device 102 receives an output signal from the air flow meter 101 and starts fuel injection control at the same time as an ignition switch 104 is closed. Here, since the heating element of the air flow meter 101 is held at a predetermined temperature in advance, the behavior shown by the solid line in FIG. 5 does not occur, and the fuel injection control device 102 incorrectly calculates the fuel injection amount. There is no.

Here, it is desirable that the temperature maintained by the heating element of the air flow meter 101 when the ignition switch 104 is turned off is the same as the temperature maintained during operation of the engine. Ignition switch 1 at this time
The behavior when 04 is ON is shown by the broken line in FIG.
Always measure accurate air volume. At this time, the power supplied to the air flow meter is the same as when the ignition switch is ON.

If the capacity of the battery 103 is not enough to keep the heating element of the air flow meter 101 at the above-mentioned temperature, it is preferable to keep the temperature below the above-mentioned temperature to reduce the power consumption. In this case, the characteristics when the ignition switch 104 is turned on behave as indicated by a dashed line in FIG. In this case, the output voltage rise when the power is turned on increases as the temperature at which the heating element is held is lower. Therefore, it is preferable to set an appropriate temperature that satisfies both requirements from the capacity of the battery and the performance at the time of starting the engine. At this time, the electric power supplied to the air flow meter becomes smaller than when the ignition is turned on.

FIG. 4 shows another embodiment of the present invention.
When the ignition switch 104 is OFF, the air flow meter 101 receives power supply via the fuel injection control device 102. Further, the fuel injection control device 102 is provided with a function of controlling the power supplied to the air flow meter 101. For example, when power is supplied to the air flow meter for a predetermined time or longer, the power of the battery 103 is prevented in order to prevent a decrease in energy. A function of stopping the supply or detecting a decrease in energy based on the supply voltage of the battery and stopping the supply of electricity is added. Thus, it is possible to prevent a decrease in the energy of the battery 103 due to the continuous supply of electricity to the air flow meter 101 when the engine is not operated for a long time.

In this embodiment, the function of controlling the electricity supplied to the air flow meter 101 is provided by the fuel injection control device 102.
The function is provided by the battery and the air flow meter 101.
May be provided at any location as long as it is between the heating elements of
As other places, an air flow meter, independently provided in the middle of wiring, and the like can be considered.

In the above description, the embodiment in which a hot wire air flow meter is used has been extended. However, the present invention can be applied to any device for directly or indirectly detecting the intake air amount of an engine. Good starting performance can be ensured.

[0020]

According to the present invention, good starting performance of the engine can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 illustrates the present invention.

FIG. 3 illustrates the present invention.

FIG. 4 is a diagram showing an embodiment of the present invention.

FIG. 5 shows an example of the present invention and the behavior when the present invention is not used.

[Explanation of symbols]

3 ... Air flow sensor, 5 ... Throttle valve body, 7 ... Engine, 22 ... Idle speed control valve.

──────────────────────────────────────────────────続 き Continued on the front page (56) References JP-A-63-45508 (JP, A) JP-A-62-184347 (JP, A) JP-A-7-224712 (JP, A) JP-A-3-3 273116 (JP, A) JP-A-5-79877 (JP, A) JP-A-62-233445 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/00-41 / 40 F02D 43/00-45/00

Claims (3)

(57) [Claims] A means for directly or indirectly detecting the amount of intake air of the internal combustion engine; a means for supplying electricity to the means for directly or indirectly detecting the amount of intake air; In an engine control device having means for supplying electricity to means for directly or indirectly detecting the amount of intake air, the amount of electric power supplied to the means for directly or indirectly detecting the amount of intake air while the internal combustion engine is stopped. Is an electric power supplied to a means for directly or indirectly detecting the amount of intake air during operation of the internal combustion engine. 2. The engine control device according to claim 1, wherein during operation of the internal combustion engine is stopped, electricity is not supplied to the means for directly or indirectly detecting the intake air amount for a predetermined time or more. 3. The method according to claim 1, wherein when the supply voltage of the means for supplying electricity to the means for directly or indirectly detecting the amount of intake air is smaller than a predetermined value, the amount of intake air is directly or indirectly measured. An engine control device characterized in that no electric power is supplied to a means for detecting electric power.