JPS60119344A - Control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the fuel consumption rate of an engine from deteriorating and as well to prevent hydrogen sulfide and fresh gas in exhaust gas from entering, by compensating the amount of fuel injection and as well the timing of ignition in accordance with the difference between an actual exhaust gas temperature and a desired exhaust temperature to control the fuel injection and the ignition timing. CONSTITUTION:There are provided a fuel injection supply means M5 for supplying fuel into a cylinder M4 in an internal combustion engine M1, and an ignition means igniting the mixture of air and fuel in the cylinder M4. A computing means compensates the amount of fuel fed from the fuel supply means M5 and the timing of ignition by the ignition means so that the temperature of exhaust gas detected by the exhaust gas temperature detecting means M3 varies toward a desired value which is set in accordance with the operating condition of the internal combustion engine that is detected by an operating condition detecting means M6. Thus, it is possible to prevent the fuel consumption rate of the engine from deteriorating and as well to prevent hydrogen sulfide and fresh gas in exhaust gas from entering.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device that controls the fuel injection amount and ignition timing of an internal combustion engine in accordance with exhaust temperature.

[Prior art] Some internal combustion engines, such as those used in automobiles, have a three-way catalytic converter installed in their exhaust system in order to reduce harmful components in the exhaust gas. In order to improve the purification zone, an air-fuel ratio sensor is installed in the exhaust system, and based on the air-fuel ratio detection signal detected by this sensor, the air-fuel ratio of the mixture supplied to the internal combustion engine cylinders is feedback-controlled to near the stoichiometric air-fuel ratio. An electronic engine control device is provided. In addition, in general, in internal combustion engines that perform such feedback control of the air-fuel ratio, the air-fuel ratio fee is adjusted to ensure high output and maintain good drivability during high-speed, high-load operation of the internal combustion engine. Dopuck control is stopped, and open-loop control is performed to increase the fuel injection amount according to the intake air amount and throttle opening.

However, open-loop control is used to inject fuel!
When controlling the amount of i1'l, if the air-fuel ratio deviates to the lean side due to variations in the performance of control parts, the exhaust temperature will rise abnormally and the exhaust system parts such as the catalyst will deteriorate. In such a case, a method of detecting the exhaust gas temperature and controlling the fuel injection amount to increase when the exhaust temperature becomes higher than a preset target exhaust exhaust gas temperature is disclosed in Japanese Patent Laid-Open No. 57-7.
This method has been proposed in Japanese Patent No. 6234.

However, in the above-mentioned air-fuel ratio control, based on such exhaust temperature (if the increase control is performed frequently), the air-fuel ratio becomes excessively rich and the fuel consumption rate worsens.
Raw gas and hydrogen sulfide may get mixed into the exhaust and cause a bad odor.

[Object of the Invention] In view of the above-mentioned problems, the present invention provides a system for increasing the amount of fuel and controlling the ignition timing when the exhaust temperature rises abnormally when feedback control based on the air-fuel ratio is not performed. It is an object of the present invention to provide a control device for an internal combustion engine that can control the exhaust temperature to be lowered with the lowest fuel consumption while keeping the fuel injection amount low by performing advance angle control.

[Structure of the Invention] In order to achieve this object, the present invention, as shown in the basic configuration diagram of FIG.
and the cylinder M4 of the internal combustion engine M1.
a fuel supply means M5 for supplying fuel to the engine; an ignition means M6 for igniting the mixture of air and fuel in the cylinder M4 of the internal combustion engine M1; Correcting the amount of fuel supplied from the fuel supply means and the ignition timing by the ignition means so that the temperature changes toward a target exhaust temperature set according to the operating state of the internal combustion engine detected by the detection means M2. The gist of the present invention is a control device for an internal combustion engine, which is equipped with an arithmetic control means and -5-.

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

[Embodiment] In FIG. 2, reference numeral 1 denotes a known four-stroke spark ignition internal combustion engine mounted on an automobile, which takes in combustion air through an air cleaner 2, an intake pipe 3, and a throttle valve 4. Also,
Fuel is supplied from a fuel system (not shown) through fuel injection valves 5 as fuel supply means provided corresponding to each cylinder. After combustion, the exhaust gas passes through an exhaust manifold 6, an exhaust pipe 7, and a three-way catalytic converter 8, and is released into the atmosphere. intake pipe 3
There is a potentiometer-type intake air amount sensor 10 that detects the intake air amount taken into the internal combustion engine 1 and outputs an analog voltage according to the intake air amount, and a potentiometer type intake air amount sensor 10 that detects the temperature of the air taken into the internal combustion engine 1 and outputs an analog voltage according to the intake air amount. A thermistor-type intake air temperature sensor 12 that outputs an analog voltage signal according to the temperature is installed. Also,
The internal combustion engine 1 includes a thermistor type water temperature sensor 13 that detects the cooling water temperature and outputs an analog voltage signal according to the cooling water temperature.
-6- is installed in the exhaust manifold 6.
An air-fuel ratio sensor 14 is installed which detects the air-fuel ratio from the elemental concentration and outputs a high-level signal when the air-fuel ratio is rich and smaller than the stoichiometric air-fuel ratio, and outputs a low-level signal when the air-fuel ratio is lean and larger than the stoichiometric air-fuel ratio. 15 is a pickup coil type rotation speed sensor installed in the distributor 16;
The rotor of the distributor 16 outputs a pulse signal with a frequency corresponding to the rotation speed of the crankshaft of the internal combustion engine 1. Note that the internal combustion engine rotational speed can also be detected by extracting an ignition pulse signal from the primary side of the ignition coil in the igniter 17 as a rotational speed signal. Reference numeral 18 denotes a throttle sensor that detects the opening degree of the throttles 1 to 3 and outputs a digital signal corresponding to the opening degree. In addition, the intake air 11Q detected by the above-mentioned intake air amount sensor 1o and the rotation speed sensor 1
The ratio Q/N to the rotation speed N detected by the rotation speed sensor 5 is used as the internal combustion engine load, and here, the combination of the rotation speed sensor 15 and the intake air amount sensor 10 constitutes a load detection means. 19 is a thermistor 7 installed in the exhaust pipe 7. A set of exhaust temperature sensors outputs an analog voltage signal according to the exhaust temperature. A control circuit 20 as an arithmetic control means calculates the 1m fuel capacity and ignition timing based on the detection signals of each sensor 10, 12, 13, 14, 15, 18, 19, and adjusts the fuel injection valve according to the injection amount data. By controlling the opening time of the valve 5 and controlling the igniter 17 according to the ignition timing data, the ignition timing of a spark plug (not shown) is advanced or retarded.

Next, the control circuit 2o will be explained with reference to FIG. The control circuit 20 is composed of a microcomputer, and has 10
0 is a CPU that executes various arithmetic and control processes, and 101 is a rotational speed counter that counts the internal combustion engine rotational speed based on a signal from a rotational speed sensor 15. 102 is an interrupt control unit which receives an interrupt command signal synchronized with the rotation of the internal combustion engine from the rotation speed counter 101, and transmits the C through the common bus 103.
An interrupt signal is output to the PU100. 104 is a digital input boat that inputs digital signals from the air-fuel ratio sensor 14 and throttle sensor 18 and transmits them to C-8-PLJloo. 105 is an analog input port consisting of an analog multiplexer and an A/D converter, and the intake air amount sensor 10. It has a function of sequentially converting each analog detection signal from the intake temperature sensor 12, water temperature sensor 13, and exhaust temperature sensor 19 into digital signals and causing the CPU 100 to read the digital signals.

A power supply circuit 106 supplies power to a RAM 107, which will be described later. The power supply circuit 106 is directly connected to the battery 21' without passing through the key switch 18. Therefore, the RAM 107 is a non-volatile memory to which power is always applied without passing through the key switch 22, and whose stored contents are not lost even if the key switch 22 is turned off and the engine is stopped, and the amount of correction necessary for various calculations, etc. is stored here in a readable and writable manner. A power supply circuit 108 supplies power to parts other than the RAM 107. A ROM 109 is a fixed memory that stores program data, constants necessary for calculations, map data, and the like.

110 and 111 are output circuits consisting of latches, down counters, amplifiers, etc., and one output circuit -9-110 is a CPU 100T-a pulse that gives the opening time of the fuel injection valve 5 corresponding to the calculated fuel injection amount. A signal is generated and applied to each fuel injection valve 5. The other output circuit 11
1 applies an ignition signal to the igniter 17 according to the ignition timing calculated by the CPU 100, whereby the igniter 17 causes the primary current to flow through the ignition coil, and by cutting off the primary current of the ignition coil at the optimum ignition timing, ignition is started. Apply high voltage to the plug to ignite it. The timer 112 is a circuit that generates a clock pulse signal and measures elapsed time.
It outputs a clock signal to the CPU 100 and a time interrupt signal to the interrupt control unit 102.

Next, referring to the flowchart in FIG.
The operation of No. 11 circuit will be explained.

When entering the routine, first, in step 210, a basic fuel injection amount 1i1 is calculated from the internal combustion engine rotation speed and intake air amount data detected by each sensor, and this basic fuel injection amount is calculated based on the water temperature data and intake air temperature data. The fuel injection amount -10- (time) τ is calculated by correcting it according to the internal combustion engine state such as data. Next, proceed to step 220,
The basic ignition timing is determined from the detected data of the internal combustion engine rotation speed and the intake air amount, and the ignition timing θ is calculated by advancing or retarding this basic ignition timing depending on the warm-up state of the internal combustion engine.

In step 230, the CPU 10 transmits the rotational speed data N1 from the rotational speed sensor 15, the exhaust temperature data Tx from the exhaust gas thirst sensor 19, and the intake air amount data Q from the intake air amount sensor 10.
Take it to 0. Then, step 240 is executed, and the internal combustion engine load Q/N is determined by the ratio of the intake air amount Q and the rotational speed N.
and the rotation speed data N, it is determined whether the internal combustion engine is in a predetermined high load high rotation range.

Here, if the internal combustion engine is not in the high load high speed range, jump to step 320, set the fuel injection amount (time) τ obtained in step 210 in the counter of the output circuit 110,
The ignition timing θ determined in step 220 is set in the counter of the output circuit 111.

On the other hand, if it is determined that the internal combustion engine is being operated in a high load/high rotation range, the process goes to step 240 where [Y-11-ESJ is selected, and the process then proceeds to step 250 where the detected internal combustion engine rotation speed N and load Q are determined. /N determines the target exhaust mTN. Here, the target exhaust gas mTs is stored in advance in the RAM 107 or ROM 109 as table data, as shown in FIG. and,
Execute step 260, and the difference ΔT between the target exhaust ff1T (to) and the actual exhaust mTx taken in step 230.
(Tx - TN), and then in step 270, it is determined whether or not this difference is zero. If the difference is zero, the exhaust 1fiTX is equal to the target exhaust mTN, and fuel injection is performed. Step 3 does not require correction to the amount or ignition timing.
Jump to 20.

On the other hand, when the difference ΔK is not zero, in step 270 rN
It is determined that it is OJ, and then the process proceeds to step 280, where the exhaust
The correction amount Kt of the fuel injection amount τ is calculated from the difference ΔT between Tx and the target exhaust temperature TN. As shown in the graph of FIG. 5(B), the correction ffKt is calculated as a function of the difference △
The RAM 107 is stored in advance in the form of a set of number-12 with T as a variable or as table data.
Or, it is stored in the ROM 109, and the correction IKt is calculated based on this difference. In step 290, the exhaust m
θ is set as the correction advance angle of the ignition timing θ based on the difference ΔT between Tx and the target exhaust temperature T8. As shown in the graph of FIG. 5(C), the corrected advance angle θ is created as a function of the difference of 6 positions, and is stored in advance in the RAM 107 or ROM 109 in the form of a mathematical formula using the difference of 6 positions as a variable or as table data. θ is determined from this difference ΔT in the corrected advance angle.

The process then proceeds to step 300, where the fuel injection amount τ is corrected by the correction amount Kt, and the process proceeds to step 310, where the ignition timing θ is corrected by the corrected advance angle θ. As shown in the graphs of FIGS. 5(B) and 5(C), when the exhaust gas temperature Tx is greater than the target exhaust temperature Tl,l and the difference is positive,
The correction IKt becomes a positive correction amount to perform an increase correction, and similarly, when the difference 6 teeth is positive, the correction advance angle θ becomes a positive correction advance angle to perform an advance angle correction. Also, conversely, the target exhaust mT
If h is greater than exhaust IRT x difference and T is negative, -
13- The correction amount Kt becomes negative and the fuel injection amount τ is reduced and corrected, and similarly, if the difference is negative, θ also becomes an angle in the corrected advance angle and the ignition timing θ is retarded. It will be done.

The corrected fuel injection amount τ and ignition timing θ corrected in this way are output to the output circuit 110 in step 320.
and 111 counter, and the exhaust ITx reaches the target exhaust temperature T1. When the temperature is higher than I, the fuel is injected from the fuel injection valve 5 and the ignition timing is advanced, thereby lowering the exhaust temperature. The exhaust temperature can be lowered depending on the consumption amount.

In this way, in this embodiment, exhaust lTx > target exhaust mT
In the case of s, the increased amount of fuel for lowering Tx can be saved by adjusting the ignition timing to the advanced side. Also, T
In the case of X<TN, it is possible to further reduce fuel consumption and save by retarding the ignition to compensate for the amount of fuel loss to increase TX and setting θ to zero at -14-. Become. In this case, Kt becomes a graph in which the slope of Kt on the negative side of the six guns is larger, as shown in FIG. 6 (A>).

[Effects of the Invention] As explained above, according to the control device for an internal combustion engine according to the present invention, the ignition timing as well as the fuel injection amount are corrected according to the difference between the actual exhaust gas temperature and the target exhaust temperature. )1 Since it performs quantity control and ignition timing control, even if control is performed frequently to lower exhaust temperature when the internal combustion engine is under high load and speed, the exhaust temperature can be lowered while minimizing the increase in fuel injection amount. This makes it possible to prevent fuel consumption from deteriorating and to prevent hydrogen sulfide and raw gas from entering the exhaust gas.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is an overall configuration diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of its control circuit.
FIG. 4 shows flowcharts 1 to 5 showing the operation of the control circuit.
Figure (A) is a data table of target exhaust temperature, Figure 5 (B) is a graph showing the relationship between the difference △T between exhaust temperature and target exhaust temperature and the correction amount, Figure 5 (C ) is a graph showing the relationship between circumferential difference ΔT and corrected advance angle, FIG. 6 (A>
6 is a graph showing the relationship between the six guns and the correction amount in another control example, and FIG. 6(B) is a graph showing the relationship between the six guns and the correction advance angle in the control example. 5...Fuel injection valve 10...Intake air amount sensor 15...Rotational speed sensor 17...Igniter 19...Exhaust temperature sensor 20...Control circuit agent Patent attorney Tsutomu Sadachi and 1 other person-16 - Figure 1 Figure 2 (B) (C) Figure 6 (A) (B) 7, °“'l / (=)1

Claims (1)

[Scope of Claims] 1. An operating state detection means for an internal combustion engine; an exhaust temperature detection means for the internal combustion engine; a fuel supply means for supplying fuel to a cylinder of the internal combustion engine; an ignition means for igniting the air-fuel mixture; and an ignition means for causing the exhaust temperature detected by the exhaust temperature detection means to change toward a target exhaust temperature set according to the operating state of the internal combustion engine detected by the operating state detection means. A control device for an internal combustion engine, comprising: arithmetic control means for correcting the amount of fuel supplied from the fuel supply means and the ignition timing by the ignition means. 2. A patent in which the operating state detection means is a rotational speed detection means of an internal combustion engine, and the arithmetic control means is configured to set a target exhaust gas temperature in accordance with the rotational speed detected by the rotational speed detection means. A control system for an internal combustion engine according to claim 1. 3. The operating state detection means includes an internal combustion engine rotation speed detection means and an internal combustion engine load detection means, and the calculation control means detects the target exhaust gas temperature using the rotation speed detected by the rotation speed detection means and the load detection means. 2. The control device for an internal combustion engine according to claim 1, wherein the control device is configured to set the control device according to the applied load. 4. The arithmetic control means is configured to correct the fuel amount toward an increase side and advance the ignition timing when the exhaust gas temperature detected by the exhaust gas temperature detection means is higher than the target exhaust temperature. A control device for an internal combustion engine according to claim 3. 5. Claim 4, wherein the arithmetic control means is configured to correct the fuel amount to the reduction side and correct the ignition timing to the retard side when the exhaust gas temperature is lower than the target exhaust temperature. Control equipment for internal combustion engines. 6. Claim 4, wherein the arithmetic control means is configured to correct the fuel amount toward a reduction side and not correct the ignition timing when the exhaust gas temperature is lower than the target exhaust temperature -2-. of the internal combustion engine described