JPH10184514A - Ignition timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a phase lag angle in a region having a lower possibility that knocking is generated in the case where heavy fuel is used by judging that a fuel used in an internal combustion engine is a light or heavy fuel, and inhibiting an operation of an ignition timing phase lag means in the case where the heavy fuel is judged. SOLUTION: In a CPU 23, a phase lag control is not carried out on the basis of a signal detected by a knock sensor 19 in the case where a cooling water temperature of an engine 1 is lower than a value which is set beforehand, and an excessive collection phase lag is carried out to lag its phase by a rate led out from a map value regardless of a signal of the knock sensor 19, in the case where the cooling water temperature is lower than a value which is set beforehand, engine speed is low, and knocking is generated easily. The excessive collection phase lag is not carried out since any knocking is less prone to occur in the case where heavy fuel is used. Fuel performance is judged by comparing an air-fuel ratio of sucked mixture supplied after engine start with an air-fuel ratio of exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device for delaying the ignition timing to prevent knocking.

[0002]

2. Description of the Related Art In order to prevent knocking, an ignition timing control device in which the ignition timing is retarded in an operation region where knocking easily occurs is widely used. However,
Since retarding the ignition timing leads to deterioration in fuel efficiency and drivability, a range in which the ignition timing is retarded is made as narrow as possible. For example, JP-A-56
As in the device described in JP-A-162267, retardation is performed based on a signal from a knock sensor only when the engine speed is equal to or lower than a predetermined value and the engine load is equal to or higher than a predetermined value.

[0003]

However, even in an ignition timing control device that performs retard control based on a signal from a knock sensor, when the cooling water temperature of the engine is low, control based on the signal from the knock sensor is not performed, and the map value is not obtained. In many cases, the angle is retarded by the amount derived from. This is due to transient knocking caused by low boiling point components of the fuel adhering to the wall of the intake port when the engine is cold or when the load changes, leading to self-ignition in the combustion chamber, so-called excessive knocking. This is done to prevent the occurrence of

[0004] However, due to the above generation mechanism, the transient knock hardly occurs when a heavy fuel having a low low boiling point component is used, and the need for retardation is low. Rather, when heavy fuel is used, the amount of adhesion to the wall increases, and the air-fuel ratio is lean, so when retarded, a sharp drop in torque occurs, and acceleration is slow. This causes a problem that drivability deteriorates. The present invention has been made in view of the above circumstances, and has as its object to provide an ignition timing control device that suppresses retardation in a region where knocking is unlikely to occur when heavy fuel is used.

[0005]

According to the first aspect of the present invention, there is provided an operating state detecting means for detecting an operating state of an internal combustion engine, a cooling water temperature detecting means for detecting a cooling water temperature of the internal combustion engine, and cooling of the internal combustion engine. Ignition timing adjustment means for adjusting the ignition timing to a predetermined basic ignition timing according to the operating state when the water temperature is equal to or higher than a predetermined temperature; and when the cooling water temperature of the internal combustion engine is equal to or lower than the predetermined temperature. Is ignition timing retarding means for retarding the basic ignition timing according to the operating state by a predetermined amount, and determines whether the fuel used by the internal combustion engine is light fuel or heavy fuel. Ignition timing control for an internal combustion engine, comprising: fuel property determining means for performing ignition timing retarding means for prohibiting operation of the ignition timing retarding means when it is determined that the fuel being used is heavy fuel. An apparatus is provided. In the ignition timing control device configured as described above, when the cooling water temperature of the internal combustion engine is equal to or higher than a predetermined temperature, the ignition timing is adjusted to a predetermined basic ignition timing according to the operating state, and the cooling water temperature is set in advance. Even when the temperature is equal to or lower than the predetermined temperature, if it is determined that the fuel being used is heavy fuel, the engine is operated at the basic ignition timing according to the operating state without delay.

According to the invention of claim 2, the invention of claim 1 is further provided with a post-start elapsed time detecting means for detecting an elapsed time after the engine is started, and the elapsed time after the engine is started is predetermined. When the time exceeds the time, the operation of the retarding prohibition means is stopped, and an ignition timing control device is provided such that the ignition timing retarding means operates. In the ignition timing control device configured as described above, when the cooling water temperature of the internal combustion engine is equal to or higher than a predetermined temperature, the ignition timing is adjusted to a predetermined basic ignition timing according to the operation state, and the cooling water temperature is reduced. In the case where the temperature is equal to or lower than a predetermined temperature, even if it is determined that the fuel being used is heavy fuel, if the elapsed time after starting the engine exceeds the predetermined time, the operation is stopped. It is retarded by a predetermined amount from the basic ignition timing according to the state.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a structure according to an embodiment of the present invention. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an embodiment of the present invention, and 1 indicates an engine body to which a fuel supply control device of the present invention is applied. Reference numeral 2 denotes an intake pipe. The intake pipe 2 is provided with a fuel injection valve 3, a throttle valve 4, a pressure sensor 5 for detecting an intake pipe pressure, and an air flow meter 6 for detecting an intake air amount. Reference numeral 7 denotes an exhaust pipe. A three-way catalyst 8 for purifying the exhaust gas is attached to the exhaust pipe 7, and an air-fuel ratio sensor 9 for detecting an air-fuel ratio of the exhaust gas is attached upstream of the three-way catalyst.

The air-fuel ratio sensor 9 can only determine whether the conventional O ₂ sensor is thinner or richer than the stoichiometric air-fuel ratio, that is, lean or rich, but the air-fuel ratio of the exhaust gas over a wide range including the stoichiometric air-fuel ratio. Since a current proportional to the fuel ratio is generated (with respect to the applied voltage), the air-fuel ratio itself of the exhaust gas can be detected over a wide range. Therefore, for example, even in the state where the amount is increased during warm-up, not only the rich state but also the air-fuel ratio itself can be obtained.

Reference numeral 10 denotes a fuel tank.
The fuel within 0 is pressure-fed to the fuel injection valve 3 by the fuel pump 11, and the fuel tank 10 is provided with a fuel level sensor 12 for detecting the fuel level. Also, 1
Reference numeral 3 denotes a water temperature sensor for detecting a cooling water temperature of the engine, 14 denotes an engine speed sensor for detecting an engine speed, and 15 denotes a throttle sensor, which also serves as an idle switch for determining whether the engine is in an idle state or a non-idle state. Also serves as. In addition, 16 is an ignition plug, 17 is an igniter,
18 is a distributor. Reference numeral 19 denotes a knock sensor that detects knocking from vibration of the cylinder wall.

Reference numeral 20 denotes an engine control unit (hereinafter referred to as an ECU). The ECU 20 is composed of a digital computer, and has an input interface circuit 21 and an ADC (analog-to-digital converter) 2 connected to each other.
2. CPU (microprocessor) 23, RAM (random access memory) 24, backup RAM 24
a, a ROM (Read Only Memory) 25, and an output interface circuit 26.

The CPU 23 has an air flow meter 6, an O
The output signals of the _two sensors 9, the remaining fuel sensor 12, the water temperature sensor 13, the engine speed sensor 14, the throttle sensor 15 and the like are input via the input interface circuit 21 or further via the ADC 22. The CPU 23 performs calculations to be described later from the values of the various sensors and the values stored in the ROM 25 in advance, and performs various other control calculations for performing the ignition timing control which is a feature of the present invention.

Next, the ignition timing control of the embodiment of the present invention configured as described above will be described. First, the concept will be described. In the control of the ignition timing according to this embodiment, when the coolant temperature of the engine 1 is lower than a predetermined value, the retard control based on the signal detected by the knock sensor 19 is not performed. However, even if the cooling water temperature is lower than a predetermined value, the engine speed is low,
Under conditions where knocking is likely to occur, to avoid transient knocking when a load change occurs,
Transient correction retarding is performed to retard by the amount derived from the map value without depending on the signal of knock sensor 19. However, when heavy fuel is used, knocking is unlikely to occur, so that the transient correction retard is not executed.

FIG. 2 is a flowchart of a routine of the ignition timing control according to the first embodiment of the present invention, which controls the execution of the transient correction retard based on the above idea. Therefore, the determination of the water temperature in step 201, that is, the cooling water temperature e
thw is lower than a predetermined threshold value ETHWATRN, and the engine speed is determined in step 202, that is, the engine speed ene obtained from the output of the engine speed sensor is set to a predetermined threshold value E.
In addition to determining whether the fuel is lower than NEATRN, it is determined in step 203 whether the fuel is a low boiling point fuel.
The process proceeds to step 4 to turn on the transient correction delay execution flag, and otherwise proceeds to step 205 to turn off the transient correction delay execution flag. In the above flowchart, the addition of step 203 is a characteristic part of the present invention. As a result, when the fuel property is a low boiling point fuel, the transient correction retardation is not executed, and accordingly, the fuel efficiency and Deterioration of drivability is prevented.

FIG. 3 is a flowchart of an ignition timing control routine according to a second embodiment of the present invention. This second
In the embodiment, after a certain period of time has elapsed after the start, the cylinder wall temperature that affects knocking rises faster than the cooling water temperature, which is an index of the engine temperature, and the frequency of occurrence of knocking even with heavy fuel is increased. In view of the increase, when the cooling water temperature is low, the engine speed is low, and heavy fuel is used, the condition for turning on the transient correction delay execution flag in the flowchart of the above-described first embodiment is as follows. However, a case where a predetermined time has elapsed after the start is added to prevent occurrence of knocking.

Therefore, steps 201 and 202 in FIG.
As in step 203, steps 301, 302, and 303 for determining the water temperature, the number of revolutions, and the fuel property are arranged. If it is determined in step 303 that the fuel property is heavy fuel, the process proceeds to step 304. Then, it is determined whether or not the elapsed time ecast after the start has exceeded a predetermined value ESTATRN. If NO, that is, if not, the process proceeds to step 306 to set the transient correction delay execution flag to O.
The process returns to FF. If the answer is YES, the process proceeds to step 305, where the transient correction delay execution flag is set to ON and the process returns.

Next, the determination of the fuel property in step 203 of FIG. 2 and step 303 of FIG. 3 will be described.
Since the heavy fuel is difficult to atomize, the amount of fuel actually sent to the combustion chamber of the engine and burned becomes smaller than the amount of fuel injected from the fuel injection valve 3, and as a result, the air-fuel ratio EXAF of the exhaust gas becomes On the other hand, light fuel is easily atomized, so that the amount of fuel actually sent to the combustion chamber of the engine 1 and burned becomes larger than the amount of fuel injected from the fuel injection valve 3. The air-fuel ratio of exhaust gas E
XAF becomes smaller (darker). Therefore, the air-fuel ratio INAF of the intake air-fuel mixture supplied after the engine is started is compared with the air-fuel ratio EXAF of the exhaust gas. If INAF> EXAF, it is determined that the fuel is light, and if INAF <EXAF, it is determined that the fuel is heavy. Is what you do. The fuel property may change only when refueling is performed, and it is considered that the fuel property does not change when refueling is not performed. Therefore, this determination is performed only when it is determined that refueling has been performed. In addition, the determination is made in the accelerated operation state because the difference between the heavy fuel and the light fuel is more likely to be clarified in the operation state where the influence of the atomization of the fuel is large.

FIG. 4 is a flowchart of a calculation for judging the fuel property based on the above concept. First, in step 401, the value FTV _OLD of the fuel gauge 12 at the end of the previous operation stored in the backup RAM and the current value FTV of the fuel gauge 12 are read, and there is a difference between these values in step 402. Is determined. as a result,
When it is determined that there is no difference, the refueling has not been performed, so the calculation is not performed, and the process ends. When it is determined that there is a difference, the process proceeds to step 403. In step 403, a change ΔTA in the opening degree TA of the throttle sensor 15 is calculated, and in step 404, whether the value is positive or negative is determined. If the value is positive, the vehicle is currently in an accelerating operation and is in an operating state suitable for the fuel property determination calculation. It is determined that there is, and the calculation from step 405 is executed.
Conversely, if negative, it is determined that the operating state is not suitable for the fuel property determination calculation, and the process returns to step 403 and repeats until the operating state is suitable for the determination calculation.

In step 405, the output VAFM of the air flow meter 6, the fuel injection time TAU calculated by the ECU 20 according to a formula described later, and the output VEXA of the A / F sensor 9.
F is read, and at step 406 the air-fuel ratio INAF of the intake air-fuel mixture and the air-fuel ratio EXAF of the exhaust gas are calculated from the output VAFM of the air flow meter 6 and the fuel injection time TAU. ΔA
/ F. Among the above, the fuel injection time TAU is corrected by a correction coefficient determined by the fuel property instruction value FQIND.
Since IN is being calculated, the value of the fuel property indicating value FQIND before refueling is used.

At step 408, ΔA / F obtained at step 407 is compared with a predetermined allowable width AH. As a result, if the absolute value of ΔA / F is smaller than the determination value AH, it is determined that the fuel property is the standard fuel and step 4
In step 09, the fuel property indicating value FQIND is set to 0 indicating that the fuel is the standard fuel, and the process ends. If the absolute value of ΔA / F is larger than the determination value AH, the routine proceeds to step 410, where it is determined whether ΔA / F is a positive value exceeding the allowable width AH. If YES, it is determined that the fuel is light fuel. Then, the routine proceeds to step 411, where the fuel property indicating value FQIND is set to a value -1 indicating light fuel, and the processing is ended.

If the determination at step 410 is NO, the air-fuel ratio INAF exceeds the predetermined width and the air-fuel ratio EX
It is indicated that the fuel is larger than AF, and it is determined that the fuel is heavy, and the routine proceeds to step 412, where the fuel property indication value FQI
ND is set to a value +1 indicating heavy fuel, and the process is terminated. The fuel property indication value F selected according to the fuel property
The value of QIND is stored in the backup RAM 24a,
It is also stored when the engine is stopped, and is not updated until the next fuel refueling is performed.

In the present embodiment, the result of the fuel property determined as described above is read into step 203 of the flowchart of FIG. 2 or step 303 of the flowchart of FIG. May be any other method as long as it can be accurately determined.

[0022]

According to the ignition timing control device of the present invention, when the cooling water temperature of the internal combustion engine is equal to or higher than a predetermined temperature, the ignition timing is adjusted to a predetermined basic ignition timing according to the operating state, Even when the cooling water temperature is equal to or lower than a predetermined temperature, if the used fuel is determined to be heavy fuel, the fuel cell is operated at the basic ignition timing according to the operating state without retarding, Drivability and fuel economy are improved.
In particular, according to the second aspect, when the cooling water temperature is equal to or lower than a predetermined temperature, and when it is determined that the fuel used is heavy fuel, the elapsed time after starting the engine is predetermined. If the predetermined time is exceeded, the ignition timing is retarded by a predetermined amount from the basic ignition timing according to the operation state,
If the knocking occurrence condition is reached earlier than the rise of the cooling water temperature, occurrence of knocking is prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a flowchart of an ignition timing control routine according to the first embodiment of the present invention.

FIG. 3 is a flowchart of an ignition timing control routine according to a second embodiment of the present invention.

FIG. 4 is a flowchart of a routine for determining a fuel property.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine body 2 ... Intake pipe 3 ... Fuel injection valve 4 ... Throttle valve 5 ... Pressure sensor 6 ... Air flow meter 7 ... Exhaust pipe 8 ... Three-way catalyst 9 ... A / F sensor 10 ... Fuel tank 11 ... Fuel pump 12 ... Fuel level sensor 13 Water temperature sensor 14 Engine speed sensor 15 Throttle sensor 16 Spark plug 17 Igniter 18 Distributor 20 ECU

Claims (2)

[Claims] 1. An operating state detecting means for detecting an operating state of an internal combustion engine, a cooling water temperature detecting means for detecting a cooling water temperature of the internal combustion engine, and an operation when the cooling water temperature of the internal combustion engine is equal to or higher than a predetermined temperature. Ignition timing adjusting means for adjusting the ignition timing to a predetermined basic ignition timing according to a state; and, when the cooling water temperature of the internal combustion engine is equal to or lower than a predetermined temperature, the basic ignition timing according to the operating state is predetermined. Ignition timing retarding means for retarding the fuel by a predetermined amount, fuel property determining means for determining whether the fuel used by the internal combustion engine is light fuel or heavy fuel, and An ignition timing control device for an internal combustion engine, comprising: retardation prohibiting means for prohibiting operation of the ignition timing retarding means when it is determined that the fuel is heavy. 2. The engine according to claim 1, further comprising a post-start elapsed time detecting means for detecting an elapsed time after the engine is started, and when the elapsed time after the engine starts exceeds a predetermined time, the retard prohibiting means is provided. 2. The ignition timing control device according to claim 1, wherein the operation is stopped and the ignition timing retarding means is activated.