JPS6183471A - Fuel injection quantity control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable a device to prevent worsening of a starting characteristic or an engine stall, by regulating a quantity of fuel by a predetermined degree of regulation if the detected temperature of exhaust gas is higher than a predetermined value only when an engine is driven at a large speed. CONSTITUTION:When exhaust gas is at a normal temperature, a device, allowing an electric current to flow in a detector 14, opens a contact 62 in an exhaust gas temperature detecting relay 6, inputting a signal H to a microcomputer 8 without turning on an alarm lamp 5. While the device, if a temperature of the exhaust gas increases to a high level blowing a fuse as an exhaust gas temperature detector 14, closes the contact 62 and starts a fuel cut control routine by both turning on the alarm lamp 5 and supplying a signal L to the microcomputer 8. And the microcomputer 8 outputs a 15% cut signal to a fuel injection valve 12 if a predetermined time passes after the temperature of the exhaust gas comes to be abnormal with an engine speed by a speed detector 22 being 600 or more. While the device, if the speed is 600 or less, performs no operation for deciding abnormality of the exhaust gas temperature and a lapse of time and for calculating a fuel cut.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a fuel injection control device for an internal combustion engine.

The device according to the invention is used for fuel injection control of internal combustion engines of the type including control based on exhaust gas temperature.

Problems to be Solved by the Invention Conventionally, in engine fuel injection control devices that operate to prevent overheating of the exhaust gas purifying catalyst in the engine's exhaust pipe, there has been a When the engine speed drops to 1, the output voltage of the alternator driven by the engine drops, and the exhaust gas temperature warning light turns on to warn of an abnormal exhaust gas temperature. In addition, in vehicles whose circuit configuration allows for both a fuse-type exhaust gas temperature sensor and a thermistor-2 exhaust gas temperature sensor, input signals from the regulator to the engine control computer must be taken from the engine control computer. The control computer sometimes activated and incorrectly determined that the catalyst was overheating, even though it was actually not. As a result of this misjudgment, the amount of fuel injection is reduced, which adversely affects engine startability.
There was a problem in that the engine stall was likely to occur.

In general, there are two types of exhaust gas temperature sensors: a fuse type and a thermistor.In vehicles that have a circuit configuration that allows both to be installed interchangeably, the signal from the exhaust gas temperature sensor circuit is connected to the engine. The connection point between the exhaust gas temperature warning light and the alternator regulator side is connected to the input terminal that applies to the control computer. Therefore, if the terminal voltage of the alternator regulator is low when starting the engine or when the engine speed drops to a state just before the engine stalls, the engine control computer will The potential of the input terminal becomes LO-, and the engine control computer determines that the exhaust gas temperature is abnormal and reduces the amount of fuel.

In addition, instead of reducing the amount of fuel when the exhaust gas temperature is abnormal,
There is also a type that increases the amount of fuel, but even in this type, if the amount of fuel is increased due to a misjudgment of abnormal exhaust gas temperature, problems such as poor startability due to over-richness, misfires, and deterioration of exhaust gas occur.

An example of a conventional fuel injection control device for an internal combustion engine that includes exhaust gas temperature detection is disclosed in Japanese Patent Application Laid-Open No. 56-81235.
It is shown in the publication No.

The purpose of the present invention is to solve the above-mentioned problems with the conventional type, and based on the idea that when the engine speed is low, it is not determined whether the exhaust gas temperature is abnormal or not. The objective is to prevent deterioration of engine startability or occurrence of engine stall during several descents, and to more appropriately perform fuel injection control of an internal combustion engine (including control) based on exhaust gas temperature.

Means for Solving the Problems and Operation The fuel injection control device for an internal combustion engine according to the present invention includes an internal combustion engine rotation detector, an exhaust gas temperature detector, a rotation speed condition determination means, an exhaust gas temperature condition determination means, and a fuel injection control device for an internal combustion engine according to the present invention. A quantity adjusting means and a fuel injection valve are provided.

The rotation detector detects the rotation of the crankshaft of the internal combustion engine.

The exhaust gas temperature detection section detects the exhaust gas temperature. The rotational speed condition determination means determines whether the internal combustion engine rotational speed is greater than a predetermined rotational speed. The exhaust gas temperature condition determining means determines whether the exhaust gas temperature detected by the exhaust gas temperature detector is higher than the predetermined temperature only when the rotation speed is determined to be higher than the predetermined rotation speed. Make a judgment. The fuel amount adjusting means adjusts the fuel amount to a predetermined degree of adjustment when the exhaust gas temperature condition determining means determines that the exhaust gas temperature is higher than a predetermined temperature. The fuel injection valve is controlled by a fuel amount adjusting means.

Embodiment A functional block diagram of the operation of a microcomputer in a fuel injection control device for an internal combustion engine according to the present invention is shown in FIG.

A fuel injection control device for an internal combustion engine as an embodiment of the present invention is shown in FIG. In FIGS. 1 and 2, the engine 1 includes an intake pipe 11, a fuel injection valve 12, a piston 13, a fuse type exhaust gas temperature detector 14, a relay 6 for the exhaust gas temperature detector, a catalyst 16, and a lid trachea 17. A rotation detector 2 is mounted on the crankshaft 21 driven by the engine 1.
2 is provided.

One terminal of the exhaust gas temperature warning light 5 is connected to a 12V power source 31 via an ignition switch 32. The other terminal of the exhaust gas temperature warning light 5 is connected to the controller/AIs 43,
connected to an alternator 41 via a regulator 42;
It is also connected to one input terminal of the microcomputer 8, and is further connected to the contact 6 of the exhaust gas temperature detector relay 6.
Connected to 2.

The coil 61 of the exhaust gas temperature detector relay 6 is connected between the exhaust gas temperature warning light 5 and the connection part of the ignition switch 32 and the exhaust gas temperature detector 14 .

The microcomputer 8 receives the output of the exhaust gas temperature detector relay 6 and the output of the rotation detector 22, performs necessary calculations, and generates an output to be supplied to the fuel injection valve.

When the exhaust gas temperature is normal, current flows through the exhaust gas temperature detector 14, so the contact 62 of the exhaust gas temperature detector relay 6 is open, the exhaust gas temperature warning light 5 does not light up, and the computer The old GH signal is supplied to the input terminal 71. When the exhaust gas temperature becomes high and the fuse serving as the exhaust gas temperature detector 14 is disconnected, the contact 62 of the exhaust gas temperature detector relay 6 is closed, the exhaust gas temperature warning light 5 lights up, and the input terminal 82 of the computer 8 is turned on.
A LOW signal is supplied to.

A fuel reduction (fuel cut) control routine in the computer 8 is shown in FIG. A fuel cut control routine is started at SO, and it is determined at SL whether the engine rotational speed N (E) is 60 Orpm or more.

If YES, it is determined in S2 whether or not the exhaust gas temperature is abnormal. If the determination in S2 is YES, it is determined in S3 whether the elapsed time t from the determination that the exhaust gas temperature is abnormal is greater than or equal to 2 seconds. If the determination in S3 is YES, the fuel injection time is cut by 15% in S4, the fuel injection time is calculated so that 85% of the fuel is injected, and a signal for driving the fuel injection valve is output.

At S5, the fuel cut control routine ends.

If the determination of Sl is negative, that is, if the engine speed is 60 rpm or less, the process directly proceeds to 85 without performing S2, 33, and S4. That is, it does not determine whether the exhaust gas temperature is abnormal, determine whether the elapsed time is greater than or equal to 2 S, and calculate the fuel injection time.

As a result, only when the engine speed becomes higher than 60 rpm, the fuel amount is cut when the engine exhaust gas temperature is abnormal. In addition, when the elapsed time t since the exhaust gas temperature was determined to be abnormal is greater than or equal to a predetermined time length, the fuel amount is automatically cut, thereby reducing noise and instantaneous exhaust gas. This is to prevent an immediate fuel cut due to a rise in gas temperature.

In the embodiments described above, a fuse-type exhaust gas temperature sensor is used as the exhaust gas temperature sensor, but a thermistor-type exhaust gas temperature sensor can be used instead. FIG. 3 shows a circuit related to the input terminal 71 in the device shown in FIG. 2 when the thermistor type exhaust gas temperature detector I5 is used.

In the circuit shown in FIG. 3, the output of the thermistor type exhaust gas temperature detection 2S15 is supplied to an analog type circuit 7 called an exhaust control computer. The output of the B computer 7 is supplied to one input terminal 81 of the computer 8. The configuration of other parts is the same as that in FIG. 2. The exhaust control 'in computer 7 has an electronic circuit 71 for discrimination operation and an output transistor 72.

The operating characteristic of the electronic circuit for discrimination operation 71 is that when the temperature detected by the detector 15 gradually rises from a low temperature and reaches T2, the output signal rapidly rises from LOW to old GH, and is thereafter maintained at HIGH. When the temperature detected by the sensor 15 gradually decreases past T2 and reaches T, which is lower than T2, the output signal suddenly drops from HIGFi to LOW, and is maintained at LOW thereafter. The output signal of this discrimination operation electronic circuit 71 is transmitted to the output transistor 72.
is applied to the base of the output transistor 72, and the output transistor 72 is turned on and off.

In the above description, a fuel amount reduction method is used to cope with the upper limit of the exhaust gas temperature, but it is also possible to use a fuel amount increase method instead of this fuel amount reduction method.

Effects of the Invention According to the present invention, the deterioration of engine starting characteristics or the occurrence of engine stall at the time of engine startup and when the engine speed drops is prevented, and the fuel injection side i' of an internal combustion engine including control based on exhaust gas temperature is prevented. Ill can be performed appropriately.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram for explaining the functions of a microcomputer operation in a device according to the present invention; FIG. 2 is a diagram showing a fuel injection control device for an internal combustion engine as an embodiment of the present invention; FIG. FIG. 4 is a flow chart showing the flow of microcomputer operation in the device shown in FIG. 2. FIG. ■...Engine, 11...Intake pipe, 12...
...Fuel injection valve, 13... Piston, 14...
・Fuse type exhaust gas temperature detector, 15...Thermistor type exhaust gas temperature detector, 16...Catalyst, I7...
Exhaust pipe, 21... Crankshaft, 22... Rotation detector, 31... Storage battery, 32... Ignition switch, 41... Alternator, 42... Regulator, 43... Rectifier , 5... Exhaust gas temperature warning light, 6... Exhaust gas temperature detector relay, 7... Exhaust control computer, 8... Microcomputer.

Claims (1)

[Scope of Claims] 1. An exhaust gas temperature detection section including an internal combustion engine rotation detector and an exhaust gas temperature detector, and a rotation speed for determining whether the internal combustion engine rotation speed is greater than a predetermined rotation speed. condition determination means, the exhaust gas temperature detected by the exhaust gas temperature detector is set to a predetermined temperature only when the rotation speed is determined to be greater than a predetermined rotation speed by the rotation speed condition determination means; Exhaust gas temperature condition determining means for determining whether the exhaust gas temperature is higher than the predetermined temperature, and when the exhaust gas temperature condition determining means determines that the exhaust gas temperature is higher than the predetermined temperature, the fuel amount is adjusted to a predetermined degree of adjustment. 1. A fuel injection control device for an internal combustion engine, comprising a fuel amount adjusting means for controlling the amount of fuel, and a fuel injection valve controlled by the fuel amount adjusting means. 2. A microcomputer is used as the rotational speed condition determination means, the exhaust gas temperature condition determination means, and the fuel amount adjustment means, and in the microcomputer, the internal combustion engine rotational speed is higher than a predetermined rotational speed. determination of whether or not the exhaust gas temperature is higher than a predetermined temperature, and calculation of the fuel amount adjustment amount based on the results of each of the above determinations. 2. The device according to claim 1, wherein the fuel injection valve is controlled based on the calculation result of the fuel amount adjustment amount. 3. Further comprising an elapsed time determining means connected to the exhaust gas temperature condition determining means and determining whether the elapsed time after determining the exhaust gas temperature condition is greater than or equal to a predetermined time length. The device according to scope 1.