JP2004108277A - Fuel injection control method and fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control method for an internal combustion engine capable of improving the startability of the engine and stabilizing the idle speed thereof after starting. <P>SOLUTION: This fuel injection control device comprises an engine temperature sensor 2 and an intake air temperature sensor 3 to detect an engine temperature and an intake air temperature in the starting of the engine. A start control correction factor indicating a larger value as the engine temperature is lower and the intake air temperature is lower and indicating a larger value as a difference between the engine temperature and the intake air temperature is smaller is calculated relative to the engine temperature and the intake air temperature. By using the start control correction factor, an initial injection time, the initial value of the warmup incremental correction factor, and a warmup control time are corrected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic control type fuel injection control method and apparatus for an internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art In an internal combustion engine that supplies fuel from an injector (an electromagnetic fuel injection valve), an electronically controlled internal combustion engine that uses a microprocessor to control an injector to inject an appropriate amount of fuel under various control conditions. Fuel injection control device (EFI) is used.
[0003]
The amount of fuel injected from the injector (injection amount) is determined by the pressure of the fuel supplied to the injector and the injection time. In general, the pressure of the fuel supplied to the injector is kept constant. It is controlled by the injection time. Therefore, the microprocessor calculates the injection time for various conditions, and the injection command signal having a signal width corresponding to the calculated injection time plus the invalid injection time for compensating the operation delay of the injector. Is supplied to the injector driving section, so that an appropriate amount of fuel is injected from the injector.
[0004]
When calculating the fuel injection time, for example, the basic injection time is calculated with respect to the rotational speed of the engine and the pressure in the intake pipe, and various types of engine temperature (cooling water temperature), intake air temperature, atmospheric pressure, and the like are calculated. The actual injection time is calculated by correcting the basic injection time by using a correction coefficient calculated for control conditions and the operating state of the engine (acceleration state, deceleration state, etc.).
[0005]
The fuel injected from the injector into the throttle body when the internal combustion engine is started is transported to the cylinder side of the engine while forming a liquid film by attaching to the inner wall surface of the throttle body and the inner wall surface of the intake manifold. In particular, if a considerable time has elapsed after the engine was stopped and the engine was started with little fuel film formed on the inner wall surface of the throttle body or the intake manifold, the injected fuel Is used to form a liquid film, so that only a part of the injected fuel reaches the cylinder. After a certain period of time has passed since the engine was started, a sufficient liquid film was formed on the inner wall surface of the throttle body and the inner wall surface of the intake manifold. To be transported to
[0006]
Therefore, in an internal combustion engine that injects fuel from the injector into the throttle body, after starting the engine, the amount of fuel to be injected at the time of the first fuel injection (usually at the time of the first fuel injection after the start of the start operation) is reduced. Perform the initial injection control to increase it more than during normal operation, and then set the startup transition period until transition to normal operation as the warm-up control period, and increase the warm-up amount during this warm-up control period to warm up the engine Control is performed.
[0007]
The amount of fuel injection required in the initial injection control and the warm-up increase control depends on the state of the engine and environmental conditions as described below.
[0008]
As described above, when the engine is started after a sufficiently long stop period, much of the injected fuel is used to form a liquid film, and the fuel sucked into the cylinder is a part of the injected fuel. Therefore, at the time of the first injection, it is required to inject more fuel than during the steady operation. Similarly, even in the early stage of the warm-up amount control, it is required to inject more fuel than usual in order to form a fuel liquid film. On the other hand, if only a short time elapses after the engine is stopped and before the engine is restarted, fuel is already applied to the inner wall surface of the throttle body and the inner wall surface of the intake manifold at the time of starting. Since the liquid film is formed, no fuel is required for forming the liquid film. Therefore, in this case, the injection amount required at the time of the first fuel injection at the time of starting is only the amount necessary for the first explosion. Similarly, fuel for forming a liquid film is not required even in the initial period of the warm-up increase control.
[0009]
Therefore, when the engine is started after a long stop period, the required injection amount increases, and when the engine is restarted immediately after stopping, the required injection amount decreases.
[0010]
When the temperature of the engine is low, the required injection amount increases because the vaporization rate of the fuel is low, and when the temperature of the engine is high, the required injection amount decreases because the vaporization rate of the fuel is high.
[0011]
Further, when the intake air temperature is low, the required injection amount increases because the air density is high, and when the intake air temperature is high, the required injection amount decreases because the air density decreases.
[0012]
By the way, in the warm-up increase control, the warm-up increase correction coefficient for determining the amount of fuel increase is determined by the passage of time in order to smoothly shift from the starting transition period to the steady state region and perform the operation of the engine without discomfort. So that it is attenuated. Usually, the attenuation characteristic of the warm-up increase correction coefficient in the warm-up increase control is often a linear characteristic as shown in FIG.
[0013]
However, in the initial period of the start-up transition period in which the warm-up increase control is performed, more fuel is required for forming the fuel liquid film, and after the middle period of the start-up transition period, the amount of fuel required for forming the liquid film is increased. As shown in FIG. 5, when the warm-up increase correction coefficient is linearly attenuated as shown in FIG. 5, the air-fuel ratio becomes too rich after the middle period of the startup transition period, and the exhaust gas characteristics deteriorate. Sometimes.
[0014]
In order to solve such a problem, as shown in FIG. 6, by combining two linear damping characteristics having different slopes and applying the higher one of the two damping characteristics, it is possible to reduce the speed at the beginning of the start-up transition period. A method of increasing the attenuation ratio of the warm-up increase correction coefficient and decreasing the attenuation ratio after the middle period of the startup transition period is also adopted. By performing such control, it is possible to prevent the air-fuel ratio from becoming rich after the middle period of the startup transition period.
[0015]
[Problems to be solved by the invention]
In the conventional warm-up increase control, the control may be performed with the warm-up increase correction coefficient having the damping characteristic as shown in FIG. 5 or the control may be performed with the damping characteristic as shown in FIG. The warm-up increase correction coefficient and the warm-up control time are determined based on the engine temperature (cooling water temperature) detected at the start of the start. Therefore, when the engine is started after a long stop period or when the engine is restarted immediately after the stop of the engine, if the engine temperature is the same, the warm-up increase control is performed using the same warm-up increase correction coefficient. However, when such control is performed, there is a problem that the air-fuel ratio becomes rich when the engine is restarted immediately after being stopped.
[0016]
Further, when the engine is restarted immediately after being stopped, the temperature in the cylinder may be higher than the detected engine temperature. In such a state, since the fuel vaporization rate is high, if the increase control is performed using the warm-up increase correction coefficient determined based on the engine temperature at the start, the air-fuel ratio shifts to the rich side and the exhaust gas Problems such as deterioration of characteristics may occur.
[0017]
Also, after the engine is started, if the rotation speed is increased by the throttle operation or the load is applied to the engine while the warm-up increase control is being performed, the temperature of the engine increases quickly and the warm-up is performed. Time is shortened. In such a case, if the warm-up increase control is continued, the fuel supply amount becomes excessive, the air-fuel ratio becomes rich, and problems such as deterioration of exhaust gas characteristics may occur.
[0018]
As described above, in the conventional fuel injection control, the length of the stop period before the start of the engine, the cylinder temperature at the start of the engine, and the like, and the state of the engine at the start, such as the temperature of the start of the engine, are not considered. Since the warm-up increase correction coefficient and the warm-up control time were determined based on the engine temperature, depending on the state of the engine, the fuel supply amount became excessive during the warm-up A problem of enrichment sometimes occurred.
[0019]
As can be seen in Japanese Patent Application Laid-Open No. H10-318019, whether the current start is a start after a long rest period, or immediately after stopping the engine, is determined by the difference between the engine temperature at the start and the intake air temperature. It is determined whether the restart has been performed, and how much the engine temperature of the engine is higher than the intake air temperature is detected. A method of correcting the injection amount in the warm-up increase control has been proposed.
[0020]
In this specification, a start immediately after stopping the engine is referred to as "restart", and a start after a certain period of time has elapsed after stopping the engine is simply referred to as "start".
[0021]
When the amount of increase in the start-time increase control is determined based on the difference between the intake air temperature and the engine temperature as in the above-described proposed method, the condition of the environment where the engine is placed and the state of the engine are determined. Since the increase is not reflected in the increase, the increase in the start-time increase control may not be accurately set.
[0022]
For example, assuming that the engine is in a cold region and the intake air temperature at the time of starting is −20 ° C. and the engine temperature is 10 ° C., the temperature difference between the two is 30 ° C. At extremely low temperatures, the vaporization rate is poor, so it is necessary to increase the initial injection amount in the start-time increase control and the injection amount in the warm-up increase control, and to set the warm-up control time longer. On the other hand, when the engine is in a warm environment and the intake air temperature at the start is 20 ° C. and the engine temperature is 50 ° C., the temperature difference between the two is 30 ° C. Is warmed to some extent and the fuel vaporization rate is high, so it is not necessary to increase both the initial injection amount and the injection amount during the warm-up increase control, and the warm-up control time can be shortened.
[0023]
As described above, the injection amount and the warm-up control time required when performing the initial injection control and the warm-up increasing control, respectively, are affected by the environmental conditions where the engine is placed and the state of the engine at the time of start. Nevertheless, in the above-mentioned proposed method, since the environmental conditions and the state of the engine were not taken into consideration, the injection amount and the warm-up control time in the initial injection control and the warm-up increase control are accurately determined. There was something I could not do.
[0024]
An object of the present invention is to provide a fuel injection control method and apparatus for an internal combustion engine that can determine an optimal initial injection amount and an injection amount during warm-up increase control according to the state of the engine at startup. Is to do.
[0025]
Another object of the present invention is to make it possible to perform a warm-up increase correction corresponding to a temperature change in a warm-up process after a start, thereby stabilizing the startability of the engine and the idle speed after the start. Accordingly, it is an object of the present invention to provide a fuel injection control method and apparatus for an internal combustion engine, which can prevent the exhaust gas characteristics from deteriorating during warm-up increase control.
[0026]
Still another object of the present invention is to increase the temperature of the engine due to an increase in rotation speed or a change in load due to a throttle operation in the process from the start of the engine to the end of the warm-up increase control. In a case where the required length of the warm-up control time becomes short, unnecessary increase of the injection amount in the warm-up increase control can be reduced, thereby reducing the fuel consumption. Another object of the present invention is to provide a fuel injection control method and apparatus for an internal combustion engine, which can improve exhaust gas characteristics.
[0027]
[Means for Solving the Problems]
The present invention provides a fuel injection system that performs an initial injection for injecting fuel from an injector during an initial injection time at the start of an internal combustion engine, and then performs a warm-up injection time calculated by multiplying a basic injection time by a warm-up correction coefficient. The warm-up fuel injection, in which fuel is injected from the injector, is performed for a warm-up control time set by calculation while the warm-up fuel increase correction coefficient is attenuated with the passage of time, and becomes steady after the warm-up control time has elapsed. The present invention relates to a fuel injection control method for an internal combustion engine that shifts to injection control during operation.
[0028]
In the present invention, an engine temperature sensor that detects the temperature of the internal combustion engine, an intake air temperature sensor that detects the intake air temperature of the internal combustion engine, show a larger value when the engine temperature is lower, and show a larger value when the intake air temperature is lower. In order to calculate a start-time control correction coefficient that shows a larger value when the difference between the engine temperature and the intake air temperature is smaller, the engine temperature and the intake air temperature detected by the engine temperature sensor and the intake air temperature sensor, respectively. A three-dimensional starting control correction coefficient calculation map to be used is prepared, and a starting control correction coefficient is calculated by searching a map for the engine temperature and the intake air temperature. The initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time are corrected using the coefficient.
[0029]
The engine temperature sensor that detects the temperature of the internal combustion engine may be one that detects the temperature of the cooling water of the engine as the temperature of the engine, and detects the temperature of the lubricating oil of the engine, the temperature of the case of the engine, the temperature of the cylinder block, and the like as the engine temperature. It may be something.
[0030]
When the engine temperature and the intake air temperature are detected at the time of starting, it is possible to determine the state of the engine at the time of starting from the level of the engine temperature and the difference between the engine temperature and the intake air temperature.
[0031]
For example, if a sufficiently long time has elapsed from the stop of the engine to the current start, the engine temperature indicates a value close to the intake air temperature (outside air temperature). Therefore, when the difference between the engine temperature and the intake air temperature is small, it can be determined that the engine stop period is long, and the ambient temperature can be determined from the temperature of the engine. That is, when the difference between the engine temperature and the intake air temperature is small and the engine temperature and the intake air temperature are low, it can be determined that the engine is started at a low temperature after being left for a long time, and the difference between the engine temperature and the intake air temperature is small. When the engine temperature and the intake air temperature are around room temperature, it can be determined that the engine is started around room temperature after being left for a long time.
[0032]
If the elapsed time from the stop of the engine is short, the engine temperature has greatly exceeded the intake air temperature because the engine has not cooled down yet, and the difference between the two has increased. Therefore, when the difference between the engine temperature and the intake air temperature is large and the engine temperature is high, it can be determined that the restart is performed in a state where the elapsed time from the stop of the engine is short. In this case, it can be determined that the closer the engine temperature is to the temperature at the time of steady operation (about 90 ° C. when the temperature of the cooling water is detected as the engine temperature), the shorter the time from the stop of the engine to the restart is. it can.
[0033]
Further, if the engine temperature is higher than the intake air temperature (the difference between the engine temperature and the intake air temperature is relatively large) but the engine temperature is lower than the temperature during steady operation, the engine It can be determined that the elapsed time from the stop is not long.
[0034]
Furthermore, when the engine temperature is high and the intake air temperature is low, it can be determined that the restart is a low-temperature restart (low-temperature restart).
[0035]
As described above, when the engine temperature and the intake air temperature are detected, the state at the time of starting the engine can be determined based on the level of the two temperatures and the difference between the two temperatures. When the start-time control correction coefficient is calculated to indicate a larger value when the intake air temperature is lower, a larger value when the intake air temperature is lower, and a larger value when the difference between the engine temperature and the intake air temperature is smaller, the starting start The time control correction coefficient changes in the same tendency as the required injection amount at the time of the initial injection and the required injection amount at the time of the warm-up increase control according to the state at the time of starting the engine, and is the same as the required warm-up control time. Vary with trends. That is, when the state at the time of starting the engine is in a state where the initial injection amount and the warm-up increasing injection amount are increased and the warm-up control time needs to be extended, the start-time control correction coefficient can be increased, When the starting state of the engine is in a state where the initial injection amount and the warm-up increasing injection amount need to be reduced and the warm-up control time needs to be shortened, the start-time control correction coefficient can be reduced.
[0036]
Therefore, if the above-described start-time control correction coefficient can be obtained, the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time can be calculated using this correction coefficient. Can be corrected.
[0037]
As described above, according to the present invention, the state at the start of the engine is determined, and the initial injection time, the initial value of the warm-up increasing correction coefficient, and the warm-up control time are determined so as to conform to the state of the engine. Therefore, not only the startability of the engine and the stabilization of the idle rotation speed after the start can be achieved, but also the deterioration of the exhaust gas characteristics during the warm-up increase control can be prevented.
[0038]
The start-time control correction coefficient is an initial value of the initial injection time, the initial value of the warm-up increase correction coefficient, and a correction coefficient commonly provided for the warm-up control time. The initial injection time correction coefficient by which the injection time is multiplied, the warm-up increase correction coefficient initial value correction coefficient by which the basic warm-up increase correction coefficient is multiplied by a predetermined basic value to calculate the initial value of the warm-up increase correction coefficient, and the warm-up control time A predetermined conversion coefficient (first injection conversion coefficient, warm-up increase conversion coefficient, and warm-up control time) determined for each correction coefficient by a warm-up control time correction coefficient that is multiplied by a basic warm-up control time determined in advance. Conversion factor).
[0039]
Therefore, when the initial injection amount, the initial value of the warm-up increase correction coefficient, and the warm-up control time are corrected using the start-time control correction coefficient, the start-time control correction coefficient includes the initial injection conversion coefficient, the warm-up increase amount. The basic initial injection time, the basic injection time, and the basic warm-up control time are calculated by multiplying the conversion coefficient and the warm-up control time, respectively, to calculate the initial injection time, the warm-up increasing injection time, and the warm-up control time. Are calculated respectively.
[0040]
In this manner, a common start-time control correction coefficient is determined for the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time, and the start-time control correction coefficient, the engine temperature, and the intake air temperature are determined. By preparing a three-dimensional map that gives the relationship and multiplying the start-time control correction coefficient obtained by searching this map by a predetermined conversion coefficient, the initial injection time, the initial value of the warm-up increase correction coefficient, and When the correction coefficient used to calculate the warm-up control time is calculated, the initial injection time, the initial value of the warm-up increase correction coefficient, and the correction coefficient used to calculate the warm-up control time are calculated. Compared to the case where the maps are individually provided, the number of map searches can be reduced, and the time required for the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time can be reduced. That.
[0041]
In a more specific embodiment of the fuel injection control method for an internal combustion engine to which the present invention is applied, at the start of the start of the internal combustion engine, the initial injection time obtained by multiplying a predetermined basic initial injection time by a start time increase correction coefficient is multiplied. After performing the initial injection for injecting fuel from the injector during the period, the warm-up injection for injecting fuel from the injector for the warm-up injection time determined by multiplying the basic injection time by the warm-up correction coefficient is performed as the basic warm-up injection. During the warm-up control time obtained by multiplying the warm-up control time correction coefficient by the warm-up control time, the warm-up increase correction coefficient is attenuated as time elapses. Shift to injection control during operation.
[0042]
When the present invention is applied to such a fuel injection control method for an internal combustion engine, an engine temperature sensor that detects the temperature of the internal combustion engine, an intake air temperature sensor that detects an intake air temperature of the internal combustion engine, and a case where the engine temperature is low A start-time control correction coefficient, which indicates a larger value as the intake air temperature is lower, shows a larger value as the intake air temperature is lower, and becomes larger as the difference between the engine temperature and the intake air temperature is smaller, and an engine temperature sensor and an intake air temperature sensor respectively. A three-dimensional start-time control correction coefficient calculation map used for calculating the detected engine temperature and intake air temperature is prepared, and the start-time control correction coefficient is multiplied to obtain a start-time increase correction coefficient. Initial injection conversion coefficient, basic warm-up increase correction coefficient that gives the basic value of the warm-up increase correction coefficient, and correction multiplied by the basic warm-up increase correction coefficient when obtaining the initial value of the warm-up increase correction coefficient A warm-up increase conversion coefficient by which the start-time control correction coefficient is multiplied to calculate the number and a warm-up control time conversion coefficient by which the start-time control correction coefficient is multiplied to calculate the warm-up control time correction coefficient are prepared in advance. After calculating the start-time control correction coefficient by searching a map for the engine temperature and the intake air temperature, the first-time control is performed by obtaining the product of the basic initial injection time, the first-time injection conversion coefficient, and the start-time control correction coefficient. Calculating an injection time; calculating a product of a basic warm-up increase correction coefficient, a warm-up increase conversion coefficient, and a start-time control correction coefficient to calculate an initial value of the warm-up increase correction coefficient; Calculating the product of the engine control time, the warm-up control time conversion coefficient, and the start-time control correction coefficient to calculate the warm-up control time.
[0043]
Generally, in an internal combustion engine, the engine temperature does not become lower than the intake air temperature (outside air temperature). If a state where the engine temperature is lower than the intake air temperature (a state where the intake air temperature is higher than the engine temperature) is detected, it is conceivable that an abnormality has occurred in the sensor. In the case where the sensor is abnormal, the intake air temperature sensor is abnormal and the engine temperature sensor is normal, the intake air temperature sensor is normal and the engine temperature sensor is abnormal, and both sensors are abnormal. The case is conceivable. Among these, when the engine temperature sensor is abnormal, even if the intake air temperature sensor is normal, the initial injection time, the warm-up increasing amount injection time, and the warm-up control time cannot be accurately controlled. . In order to control the initial injection time, the warm-up increasing injection time, and the warm-up control time, it is essential to detect at least the temperature of the engine, but start the engine after leaving the engine stopped for a long time. Except in cases, it is difficult to accurately estimate the engine temperature from only the intake air temperature.
[0044]
On the other hand, when the engine temperature sensor is normal, the initial injection time, the warm-up increasing amount injection time, and the warm-up control time can be controlled to some extent only from the engine temperature. If any of the sensors are abnormal, the initial injection time, warm-up increase injection time, and warm-up control time may not be controlled, but control is possible when the engine temperature sensor is normal. In such a region, it is preferable to control the initial injection time, the warm-up increasing injection time, and the warm-up control time with respect to the engine temperature, rather than performing no control. When the engine temperature sensor is normal, the region where the intake air temperature sensor can be definitely determined to be abnormal is the region where the engine temperature detected by the engine temperature sensor shows a value lower than the intake air temperature. Therefore, in order to minimize the influence of the sensor abnormality on the control, in the region where the engine temperature is lower than the intake air temperature, it is assumed that the engine temperature sensor is normal, It is preferable to create the above-described starting control correction coefficient calculation map so as to change the control correction coefficient.
[0045]
The present invention also provides, at the start of the start of the internal combustion engine, a warm-up fuel injection time determined by multiplying the basic fuel injection time by a warm-up fuel increase correction coefficient after performing the initial fuel injection from the injector for the initial fuel injection time. During the warm-up control time set by the calculation, the warm-up increasing correction coefficient for injecting fuel from the injector is performed while attenuating the warm-up increasing correction coefficient with time, and the warm-up control time elapses. After performing the fuel injection control method for the internal combustion engine that shifts to the injection control during the steady operation after performing, the engine temperature is also monitored during the warm-up control time, and the fuel injection amount in the warm-up increased injection during the steady-state operation is increased. It is characterized in that the initial value of the warm-up increase correction coefficient is updated according to the temperature of the engine so that the increase ratio with respect to the injection amount is a value corresponding to the temperature of the engine.
[0046]
When such control is performed, after the start operation of the engine is started, the temperature of the engine is increased due to an increase in rotation speed or a change in load due to a throttle operation in a process until the warm-up increase control is terminated. In a case where the required length of the warm-up control time becomes short, unnecessary increase of the injection amount in the warm-up increase control can be reduced, thereby reducing fuel consumption and reducing exhaust gas. The characteristics can be improved.
[0047]
The fuel injection control device for an internal combustion engine used to carry out the above-described start control method basically performs an initial injection for injecting a fuel of an injection amount determined by an initial injection time from an injector at the start of start of the internal combustion engine. A first-injection control means for causing the fuel injection from the injector during the warm-up fuel injection time determined by multiplying the basic injection time by a warm-up fuel correction coefficient; And a warm-up increasing injection control means to be performed during the period.
[0048]
In the fuel injection control device according to the present invention, an engine temperature sensor that detects the temperature of the internal combustion engine, an intake air temperature sensor that detects the intake air temperature of the internal combustion engine, and the lower the engine temperature, the larger the value. When the engine temperature and the intake air temperature are detected by the engine temperature sensor and the intake air temperature sensor, the starting control correction coefficient, which indicates a larger value as the temperature is lower, and a larger value as the difference between the engine temperature and the intake air temperature is smaller, is calculated. Storage means storing a three-dimensional start-time control correction coefficient calculation map used to calculate the start-up control coefficient and a start-up control means for calculating a start-time control correction coefficient by searching a map for the engine temperature and the intake air temperature. Time control correction coefficient calculating means is provided. In the present invention, the first injection control means further includes first injection time correction means for correcting the first injection time using the start control correction coefficient calculated by the start control correction coefficient calculation means, A warm-up increasing correction coefficient initial value correcting means for correcting the initial value of the warm-up increasing correction coefficient using the starting control correction coefficient calculated by the starting control correction coefficient calculating means; And a warm-up control time correcting means for correcting the warm-up control time using a start-time control correction coefficient calculated by the correction coefficient calculating means.
[0049]
The control device that implements the fuel injection control method according to the present invention also supplies fuel from the injector during the initial injection time determined by multiplying a predetermined basic initial injection time at the start of starting the internal combustion engine by a start-time increasing correction coefficient. Initial warm-up injection means for injecting fuel from the injector during the warm-up fuel injection time determined by multiplying the basic injection time by the warm-up fuel increase correction coefficient. A warm-up increasing injection control means for performing the warm-up increasing correction coefficient while attenuating the warm-up increasing correction coefficient over time during the warm-up control time obtained by multiplying the control time by the warm-up control time correction coefficient. Applied to an engine fuel injection control device.
[0050]
In this case, an engine temperature sensor that detects the temperature of the internal combustion engine, an intake air temperature sensor that detects the intake air temperature of the internal combustion engine, show a larger value as the engine temperature is lower, and show a larger value as the engine temperature is lower. And a start-time control correction coefficient that indicates a larger value as the difference between the engine temperature and the intake air temperature is smaller, is used to calculate the engine temperature and the intake air temperature detected by the engine temperature sensor and the intake air temperature sensor, respectively. Map storage means for storing a three-dimensional start-time control correction coefficient calculation map; first-injection determination means for determining whether or not first-time fuel injection performed at the start of starting the internal combustion engine; and first-injection determination means When the engine is determined not to be performing the first fuel injection, the engine temperature and the intake air temperature are searched for a map to calculate a start-time control correction coefficient. And control correction coefficient calculating means is provided.
[0051]
In this case, the first injection control means includes a start-up control coefficient calculated by the start-time control correction coefficient calculation means at a predetermined basic first injection time when the first injection determination means determines that the first fuel injection is not performed. An initial injection time calculating means for calculating an initial injection time by multiplying a time control correction coefficient by a predetermined initial injection conversion coefficient is provided.
[0052]
Further, the warm-up increase injection control means includes a predetermined warm-up increase conversion coefficient and a start-up increase coefficient which are set to a predetermined basic warm-up increase correction coefficient when the initial injection determination means determines that the first fuel injection is not performed. A warm-up increase correction coefficient initial value calculating means for calculating an initial value of a warm-up increase correction coefficient by multiplying the start-time control correction coefficient calculated by the time control correction coefficient calculating means; Multiplying the predetermined basic warm-up control time by the predetermined warm-up control time conversion coefficient and the start-time control correction coefficient calculated by the start-time control correction coefficient calculating means when it is determined that the control is not performed. Warm-up control time calculating means for calculating the warm-up control time according to the above, and warm-up control calculated by the warm-up control time calculating means when it is determined by the first injection determining means that the first fuel injection has already been performed. The warm-up control time measuring means that starts the measurement during the period, and the value changes over time to the initial value of the warm-up increase correction coefficient while the warm-up control time measuring means measures the warm-up control time. A warm-up increase correction coefficient calculating means for calculating a warm-up increase correction coefficient having a value exceeding 1 by multiplying the warm-up increase correction coefficient by multiplying the warm-up increase correction coefficient by 1 when the warm-up control time has elapsed. Is provided.
[0053]
The present invention also provides an initial injection control means for performing an initial injection for injecting a fuel of an injection amount determined by the initial injection time from the injector at the start of starting the internal combustion engine, and multiplying the basic injection time by a warm-up increase correction coefficient. Fuel injection for an internal combustion engine, comprising: a warm-up fuel injection control means for performing a warm-up fuel injection for injecting fuel from the injector for the obtained warm-up fuel injection time for a warm-up control time set by calculation. In the control device, the warm-up fuel injection control means includes an engine temperature monitoring means for monitoring the temperature of the engine during the warm-up control time, and a steady-state fuel injection amount in the warm-up fuel injection performed during the warm-up control time. A procedure for updating the initial value of the warm-up fuel injection amount that updates the initial value of the warm-up fuel increase correction coefficient in accordance with the engine temperature so that the increase ratio with respect to the injection amount during operation is set to a value corresponding to the engine temperature. Characterized in that a and.
[0054]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0055]
FIG. 1 shows a basic configuration of hardware of a fuel injection control device for an internal combustion engine according to the present invention. In FIG. 1, reference numeral 1 denotes a control unit (ECU) including a microprocessor having a CPU, a ROM, a RAM, a timer, and the like. It is.
[0056]
The control unit 1 detects an output of an engine temperature sensor 2 for detecting an engine temperature, an output of an intake temperature sensor 3 for detecting an intake air temperature, and a pressure (intake pressure) in an intake pipe downstream of a throttle valve. The output of the intake pressure sensor 4, the output of the throttle opening sensor 5, and the output of the pulser 6 that generates a pulse signal at a predetermined crank angle position of the engine are input.
[0057]
The engine temperature sensor 2 may be any sensor that detects the temperature of the engine. Examples of the sensor include a sensor that detects the temperature of the cooling water of the engine, the temperature of the lubricating oil in the crankcase, the temperature of the cylinder block of the engine, and the like. Although it can be used, in the present embodiment, an engine temperature sensor is configured by a water temperature sensor that detects a cooling water temperature of the engine.
[0058]
Reference numeral 7 denotes an injector driving unit to which a rectangular injection command signal is supplied from the control unit 1 when a predetermined injection timing is detected, and 8 denotes an ignition control unit to which an ignition command signal is supplied from the control unit 1 at a predetermined ignition timing. It is.
[0059]
When an injection command is given from the control unit 1, the injector drive unit 7 opens a valve of the injector by flowing a drive current to an injector (not shown) while the injection command is given, thereby allowing the fuel to flow from the injector. Inject.
[0060]
The ignition control unit 8 supplies an ignition timing signal to an ignition circuit (not shown) when the ignition command signal is supplied from the control unit 1, and causes the ignition circuit to perform an ignition operation.
[0061]
The control unit 1 causes the injector to inject fuel during an initial injection time that provides an initial injection amount that is greater than the injection amount during steady operation of the internal combustion engine (not shown) at the start of startup of the internal combustion engine. Fuel is injected from the injector during the warm-up fuel injection time calculated by multiplying the basic injection time by the warm-up fuel increase correction coefficient that attenuates as time elapses from the time when the warm-up control time elapses. Control the injector to cause In order to perform such control, in the present embodiment, the microprocessor constituting the control unit 1 executes a predetermined program to configure the control unit 1 as a function realizing unit as shown in FIG.
[0062]
In FIG. 4, reference numeral 10 denotes a map storage unit that stores a map for calculating a control correction coefficient at startup. The start-time control correction coefficient calculation map stored in the storage means indicates a larger value as the engine temperature is lower, a larger value as the intake air temperature is lower, and a difference between the engine temperature and the intake air temperature. It is a three-dimensional map used to calculate a start-time control correction coefficient Ks, which indicates a larger value as the value is smaller, with respect to the engine temperature and the intake temperature detected by the engine temperature sensor and the intake temperature sensor, respectively. It consists of a three-dimensional table storing numerical values giving the relationship between the intake air temperature and the start-time control correction coefficient.
[0063]
FIG. 11 is a conceptual diagram showing an example of the structure of the start-time control correction coefficient calculation map. As shown in the figure, the starting control correction coefficient calculation map sets the starting control correction coefficient Ks to a larger value as the engine temperature (cooling water temperature in this example) Te is lower, and to a lower intake air temperature Ta as the engine temperature Te is lower. The start-time control correction coefficient Ks is set to a large value, and the start-time control correction coefficient Ks is set to a larger value as the difference between the engine temperature and the intake air temperature is smaller.
[0064]
In the start-time control correction coefficient calculation map shown in FIG. 11, an area A in the hatched area corresponds to the state of the engine when the engine is restarted immediately after the engine is stopped (at the time of high-temperature restart). (The region where the engine temperature is high and the difference between the engine temperature and the intake air temperature is large), and the region B is when the engine is started after the engine has been stopped for a long time (when the engine is started after a long-term leaving). (A region where the difference between the engine temperature and the intake air temperature is small). A region C is a region in which the intake air temperature is higher than the engine temperature. When the engine temperature sensor is normal and only the intake air temperature sensor is abnormal, the first injection is performed with respect to the engine temperature detected by the engine temperature sensor. This is a region where the time, the warm-up increasing injection amount, and the warm-up control time can be controlled.
[0065]
In the area A, the start-time control correction coefficient Ks shows a smaller value than the area B, and in the area B, the start-time control correction coefficient Ks shows a larger value than the area A. In the area of C, assuming that the engine temperature sensor is normal and only the intake air temperature sensor is abnormal, the start-time control correction coefficient Ks changes only with respect to the change in the engine temperature. Ks becomes smaller) and is not changed with respect to the intake air temperature.
[0066]
In FIG. 4, reference numeral 11 denotes an initial injection determination unit that determines whether the first fuel injection has already been performed at the start of the start of the internal combustion engine. Reference numeral 12 denotes that the first fuel injection has been performed by the first injection determination unit 11. A start-time control correction coefficient calculating means for calculating a start-time control correction coefficient by searching a map for the engine temperature and the intake air temperature when it is determined that there is no such control.
[0067]
13, 14, and 15, the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time, respectively, when the initial injection determination means determines that the first fuel injection is not performed. The first injection time calculating means for calculating, the warm-up increase correction coefficient initial value calculating means, and the warm-up control time calculating means.
[0068]
The first injection time calculating means 13 is calculated by the starting control correction coefficient calculating means 12 to a predetermined basic first injection time TfO when the first injection determining means 11 determines that the first fuel injection is not performed. The initial injection time Tf (= TfO × TfOc × Ks) is calculated by multiplying the start-time control correction coefficient Ks by a predetermined initial injection conversion coefficient TfOc.
[0069]
Further, the warm-up increase correction coefficient initial value calculating means 14 determines a predetermined warm-up increase correction coefficient KwuO when the first injection determination means 11 determines that the first fuel injection is not performed. The initial value Kwub (= KwuO × KwuOc × Ks) of the warm-up increase correction coefficient is calculated by multiplying the increase conversion coefficient KwuOc by the start control correction coefficient Ks calculated by the start control correction coefficient calculation means 12.
[0070]
The warm-up control time calculating means 15 converts the predetermined warm-up control time conversion coefficient TwuOc to the predetermined basic warm-up control time TwuO when the initial fuel injection determination means 11 determines that the first fuel injection has not been performed. The warm-up control time Twu (= TwuO × TwuOc × Ks) is calculated by multiplying the start-time control correction coefficient Ks calculated by the start-time control correction coefficient calculation means 12.
[0071]
In FIG. 4, reference numeral 16 denotes a warm-up operation for starting the measurement of the warm-up control time Twu calculated by the warm-up control time calculating means 15 when the initial fuel injection determining means 11 determines that the first fuel injection has already been performed. The control time measuring means 17 includes an initial value Kub of the warm-up increase correction coefficient and a correction coefficient whose value changes with time while the warm-up control time measuring means 16 is measuring the warm-up control time. To calculate a warm-up increase correction coefficient Kwu (= Kub × correction coefficient whose value changes with the lapse of time) that takes a value exceeding 1 by multiplying by 1. This is a warm-up increase correction coefficient calculating unit that sets the coefficient Kwu to 1.
[0072]
Reference numeral 18 denotes an injection time calculating means for calculating the injection time, and 19 an injection command signal having a signal width corresponding to a time obtained by adding the invalid injection time to the injection time calculated by the injection time calculating means 18 to the injector drive unit 20. This is an injection command generating means to give.
[0073]
The injection time calculating means 18 gives the initial injection time calculated by the first injection amount calculating means 13 to the injection command generating means 19 as it is at the time of the first fuel injection. The warm-up increase calculated by the warm-up increase correction coefficient calculating means 17 at the basic injection time calculated for the intake air amount calculated based on the engine speed (detected from the output of the pulser 6) and the engine speed. The warm-up increased injection time is calculated by multiplying by the correction coefficient. After the completion of the measurement of the warm-up control time, the injection time during steady operation is calculated by multiplying the basic injection time by a correction coefficient obtained for various control conditions.
[0074]
In the example shown in FIG. 4, the first injection time calculating means 13, the injection time calculating means 18, and the injection command generating means 19 constitute an initial injection control means.
[0075]
Further, a warm-up increase correction coefficient initial value calculating means 14, a warm-up control time calculating means 15, a warm-up control time calculating means 16, a warm-up increase correction coefficient calculating means 17, an injection time calculating means 18, an injection command The generating means 19 constitutes a warm-up increasing injection control means.
[0076]
The algorithm of the program task executed by the microprocessor to configure the function realizing means shown in FIG. 4 is shown in FIG. 2 and FIG.
[0077]
The tasks shown in FIGS. 2 and 3 are performed at fixed time intervals (80 msec in the present embodiment). In this task, first, in step 1, the engine temperature (cooling water temperature in this example) Te and the intake air temperature Ta detected by the engine temperature sensor 2 and the intake air temperature sensor 3, respectively, are read. Is determined. This determination can be made by checking the state of a flag that is set when the first injection is performed and that is reset when the engine start operation is started.
[0078]
If it is determined in step 2 that the first injection has not been performed yet, the process proceeds to step 3 in which the engine temperature Te and the intake air temperature Ta read in step 1 are respectively changed to the starting engine temperature Tef and the starting intake air temperature. Taf.
[0079]
Next, in step 4, a starting control correction coefficient calculation map is searched for the starting engine temperature Tef and the starting intake air temperature Taf to calculate the starting control correction coefficient Ks, and then the data value is stored in the ROM of the microprocessor. Is read as the first-time injection conversion coefficient TfOc, the warm-up increase conversion coefficient KwuOc, and the warm-up control time conversion coefficient TwuOc.
[0080]
Next, in step 5, the basic initial injection time TfO stored as a data value in the ROM is read and multiplied by the initial injection conversion coefficient TfOc and the start-time control correction coefficient Ks to obtain an initial injection time Tf = TfO × TfOc × Ks. Calculate.
[0081]
Next, in step 6, a basic warm-up increase correction coefficient KwuO stored in the ROM as table data for the engine temperature is determined for the engine temperature in order to determine the injection amount at the time of the warm-up increase control. By reading and multiplying this by the warm-up increase conversion coefficient KwuOc and the start-time control correction coefficient Ks, the warm-up increase correction coefficient initial value Kwub = KwuO × KwuOc × Ks is calculated.
[0082]
In step 7, a basic warm-up control time TwuO stored in the ROM as table data is searched for the engine temperature, the search value is read, and a warm-up control time conversion coefficient TwuOc and a start-time control correction coefficient Ks is multiplied to calculate a warm-up control time Twu = TwuO × TwuOc × Ks.
[0083]
Next, in step 8, a warm-up increase correction coefficient Kwu is obtained for the next injection after the first injection. At this time, since the elapsed time of the warm-up control time is zero, the initial value Kwub of the warm-up increase correction coefficient is set as the warm-up increase correction coefficient Kwu. After performing step 8, this task is terminated, and the process proceeds to another task.
[0084]
In a task to be executed when a predetermined position is detected as a crank position at which fuel injection is performed, an injection command signal having a signal width determined from the initial injection time Tf and the invalid injection time obtained as described above. Is given to the injector drive unit, and the first injection is performed. After this injection is performed, near the top dead center of the compression stroke after approximately one rotation, the ignition control unit 8 supplies an ignition timing signal to the ignition circuit to cause the ignition circuit to perform an ignition operation, thereby causing an initial explosion. This starts the engine.
[0085]
After the first injection is performed, the engine temperature and the intake air temperature are read in step 1 of FIG. 2, and then it is determined in step 2 that the first injection has been performed. Then, the warm-up control time Twu is compared with the warm-up elapsed time Twup. As a result, when it is determined that Twup <Twu (when it is determined that the warm-up control time has not elapsed), in step 10, the basic warm-up increase correction coefficient stored as the table data in the ROM is stored. KwuO is searched for the engine temperature, and the search value is multiplied by a warm-up increase conversion coefficient KwuOc and a start-time control correction coefficient Ks to calculate an initial value Kub of the warm-up increase correction coefficient.
[0086]
As described above, in the present embodiment, the basic value of the warm-up increase correction coefficient Kwu0 is calculated by multiplying the basic warm-up increase correction coefficient Kwu0 searched for the engine temperature by the warm-up increase conversion coefficient KwuOc and the start-time control correction coefficient Ks. , The initial value Kweb of the warm-up increase correction coefficient is updated as needed with respect to the engine temperature.
[0087]
Next, at step 11, the warm-up increase correction coefficient Kwu used for calculating the actual warm-up increase injection time is calculated by the following equation (1). * Is a multiplication symbol.
[0088]
Kwu = {(Ktub-1) * (Twu-Tupup) / Twu} +1 (1)
In the equation (1), (Twu-Tup) / Twu is an elapsed time attenuation coefficient that changes with the lapse of time, and this coefficient is linearly changed from the initial value 1 with the lapse of the warm-up elapsed time Twup. It decays and becomes zero when the warm-up elapsed time Twup becomes equal to Twu. When the warm-up increase correction coefficient Kwu is obtained by directly multiplying the elapsed time attenuation rate by the warm-up increase correction coefficient initial value Kub, the correction coefficient Kwu converges to zero. An increment rate is obtained by subtracting 1 from the correction coefficient initial value Kub to obtain (Kub-1), multiplying this by an elapsed time attenuation coefficient (Twu-Tup) / Twu, and finally adding 1 to the increment rate. Thus, the warm-up increase correction coefficient Kwu is obtained.
[0089]
Next, after the elapsed time Twup is incremented in step 12, this task is terminated, and the process proceeds to the next task.
[0090]
In another task executed when the crank angle position at which fuel injection is performed is detected, the warm-up increase injection time is calculated by multiplying the basic injection time by the warm-up increase correction coefficient Kwu obtained as described above. An injection command signal having a signal width determined based on the calculated injection time is given to the injector drive unit at a predetermined crank angle position to cause fuel injection.
[0091]
Until the warm-up control time elapses, Steps 1 and 2 and Steps 9 to 12 are repeated, and the warm-up increase control is performed.
[0092]
When it is determined in Step 9 that Twup ≧ Twu (when it is determined that the warm-up control time has elapsed), the process proceeds to Step 13 and the warm-up increase correction coefficient Kwu = 1, and the warm-up increase control is performed. finish.
[0093]
In the case of the algorithm shown in FIGS. 2 and 3, step 2 constitutes the first-time injection determining means 11 and step 4 constitutes the starting-time control correction coefficient calculating means 12. Steps 4 and 5 constitute the initial injection time computing means 13, and steps 4 and 6 constitute the warm-up increase correction coefficient initial value computing means 14. Further, the warm-up control time calculating means 15 is constituted by Steps 4 and 7, and the warm-up control time measuring means 17 is constituted by Steps 9 and 12. Step 8 and steps 10 and 11 constitute the warm-up increase correction coefficient calculating means 17.
[0094]
FIGS. 7 to 10 show some examples of characteristics of changes in the warm-up amount correction coefficient Kwu, the engine temperature Te, and the intake air temperature Ta with respect to time t when fuel injection at the time of starting is controlled by the method of the present invention. Was.
[0095]
FIG. 7 shows characteristics when the engine is started after being stopped for a long time in a cold region (at the time of low-temperature start), and FIG. 8 is a diagram when the engine is stopped immediately after being stopped in a cold region ( (At low temperature restart). FIG. 9 shows the characteristics when the engine is started in a warm region or in a warm period when the elapsed time from the stop to the start is long and the difference between the engine temperature and the intake air temperature is not so large (at a high temperature start). FIG. 10 shows characteristics when the engine is started immediately after being stopped in a warm region (at the time of high-temperature restart).
[0096]
As in the above embodiment, the engine temperature is monitored even during the warm-up increase control, and the increase ratio of the warm-up increase injection amount to the injection amount at the time of steady operation is set to a value corresponding to the engine temperature. If the initial value of the warm-up increase correction coefficient is updated in accordance with the temperature of the engine as described above, in the process from the start of the engine to the end of the warm-up increase control, the rotation speed by the throttle operation is reduced. In the event that the engine temperature rises due to a rise or load change, and the length of the required warm-up control time is shortened, the unnecessary increase in the injection amount in the warm-up control is reduced. Therefore, reduction of fuel consumption and improvement of exhaust gas characteristics can be achieved.
[0097]
【The invention's effect】
As described above, according to the present invention, the state at the start of the engine is determined based on the engine temperature and the intake air temperature, and the initial injection amount and the initial value of the warm-up increase correction coefficient are adjusted so as to conform to the engine state. Since the value and the warm-up control time can be set, not only the startability of the engine and the stabilization of the idling speed during the warm-up after the start can be achieved, but also the starting which is not adapted to the state of the engine. Exhaust gas characteristics from the start to the end of the warm-up operation can be improved as compared with the case where the time control is performed.
[0098]
Further, according to the present invention, a common start-time control correction coefficient is determined for the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time, and the start-time control correction coefficient and the engine temperature and intake air are determined. A map that gives a relationship with the temperature is prepared, and the initial control time and the initial value of the warm-up increase correction coefficient are calculated by multiplying the start-time control correction coefficient obtained by searching this map by a predetermined conversion coefficient. And the correction coefficient used to calculate the warm-up control time, so that the initial injection time, the initial value of the warm-up increase correction coefficient, and the correction coefficient used when calculating the warm-up control time are the engine temperature. The number of map searches is reduced compared to the case where maps for obtaining the temperature and the intake air temperature are individually provided, and the initial injection time, the initial value of the warm-up increase correction coefficient, and the warm-up control time are calculated. To Advantage that it is possible to reduce the time to obtain.
[0099]
Further, in the present invention, the engine temperature is monitored even during the warm-up increase control, and the engine is controlled so that the increase ratio of the warm-up increase injection amount to the injection amount during the steady operation is set to a value corresponding to the engine temperature. If the initial value of the warm-up increase correction coefficient is updated in accordance with the temperature of the engine, the rotation speed by the throttle operation is changed in the process from the start of the engine to the end of the warm-up increase control. In the event that the engine temperature rises due to a rise or load change, and the length of the required warm-up control time is shortened, the unnecessary increase in the injection amount in the warm-up control is reduced. As a result, it is possible to reduce fuel consumption and improve exhaust gas characteristics.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a hardware configuration example of a fuel injection control device for an internal combustion engine according to the present invention.
FIG. 2 is a flowchart showing a part of an algorithm of one task executed by a microprocessor in the embodiment of the present invention.
FIG. 3 is a flowchart illustrating another part of the algorithm of one task executed by the microprocessor in the embodiment of the present invention.
FIG. 4 is a functional block diagram showing function realizing means realized by a microprocessor in the embodiment of the present invention.
FIG. 5 is a graph showing an example of an attenuation characteristic of a warm-up increase correction coefficient at the time of warm-up increase control according to a conventional technique.
FIG. 6 is a graph showing another example of the attenuation characteristic of the warm-up increase correction coefficient at the time of the warm-up increase control according to the related art.
FIG. 7 is a graph illustrating an example of a characteristic of a temporal change of a warm-up increase correction coefficient, an engine temperature, and an intake air temperature at the time of a low-temperature start of an engine when control is performed according to the method of the present invention.
FIG. 8 is a graph showing an example of a characteristic of a temporal change of a warm-up increase correction coefficient, an engine temperature, and an intake air temperature when the engine is restarted at a low temperature when the control is performed according to the method of the present invention. .
FIG. 9 is a graph showing an example of a characteristic of a temporal change of a warm-up increase correction coefficient, an engine temperature, and an intake air temperature when the engine is started at a high temperature when control is performed according to the method of the present invention.
FIG. 10 is a graph showing an example of a characteristic of a temporal change of a warm-up increase correction coefficient, an engine temperature, and an intake air temperature when the engine is restarted at a high temperature when control is performed by the method of the present invention. .
FIG. 11 is a schematic diagram schematically showing an example of the structure of a start-time control correction coefficient calculation map used in the present invention.
[Explanation of symbols]
1: control unit, 2: engine temperature sensor, 3: intake temperature sensor, 4: intake pressure sensor, 6: pulser, 7: injector drive unit, 8: ignition control unit.

Claims (7)

At the start of the start of the internal combustion engine, after performing the initial injection for injecting fuel from the injector for the initial injection time, from the injector for the warm-up increasing injection time obtained by multiplying the basic injection time by the warm-up increasing correction coefficient. The warm-up increasing injection for injecting the fuel is performed for a warm-up control time set by calculation while attenuating the warm-up increasing correction coefficient with the passage of time, and becomes steady after the warm-up control time elapses. A fuel injection control method for an internal combustion engine that shifts to injection control during operation,
An engine temperature sensor for detecting a temperature of the internal combustion engine,
An intake air temperature sensor for detecting an intake air temperature of the internal combustion engine,
The starting control correction coefficient indicates a larger value as the engine temperature is lower, a larger value as the intake air temperature is lower, and a larger value as the difference between the engine temperature and the intake air temperature is smaller, A three-dimensional starting control correction coefficient calculation map used to calculate the engine temperature and the intake air temperature detected by the engine temperature sensor and the intake air temperature sensor, respectively, is prepared.
After calculating the start control correction coefficient by searching the map for the engine temperature and the intake air temperature, the initial injection time and the initial value of the warm-up increase correction coefficient are calculated using the calculated start control correction coefficient. And correcting the warm-up control time,
A fuel injection control method for an internal combustion engine. At the start of the start of the internal combustion engine, after performing an initial injection for injecting fuel from the injector for an initial injection time obtained by multiplying a predetermined basic initial injection time by a start time increase correction coefficient, and then warming up the basic injection time. The warm-up fuel injection from the injector during the warm-up fuel injection time obtained by multiplying the fuel injection amount by the boost correction coefficient, the warm-up control time obtained by multiplying the basic warm-up control time by the warm-up control time correction coefficient During the fuel injection control method for an internal combustion engine, the warm-up increase correction coefficient is performed while being attenuated as time elapses, and the control shifts to injection control during steady operation after the warm-up control time has elapsed.
An engine temperature sensor for detecting a temperature of the internal combustion engine,
An intake air temperature sensor for detecting an intake air temperature of the internal combustion engine,
The starting control correction coefficient indicates a larger value as the engine temperature is lower, a larger value as the intake air temperature is lower, and a larger value as the difference between the engine temperature and the intake air temperature is smaller, A three-dimensional starting control correction coefficient calculation map used to calculate the engine temperature and the intake air temperature detected by the engine temperature sensor and the intake air temperature sensor, respectively, is prepared.
An initial injection conversion coefficient by which the start-time control correction coefficient is multiplied to obtain the start-time increase correction coefficient, a basic warm-up increase correction coefficient that gives a basic value of the warm-up increase correction coefficient, and a warm-up increase correction coefficient In order to calculate a correction coefficient for multiplying the basic warm-up increase correction coefficient when calculating the initial value, a warm-up increase conversion coefficient by which the start-time control correction coefficient is multiplied, and a warm-up control time correction coefficient for calculating the warm-up control time correction coefficient. A warm-up control time conversion coefficient to be multiplied by the start-time control correction coefficient is prepared in advance,
After calculating the starting control correction coefficient by searching the map for the engine temperature and the intake air temperature, obtaining a product of the basic initial injection time, the initial injection conversion coefficient, and the starting control correction coefficient. And calculating the initial value of the warm-up increase correction coefficient by calculating the product of the basic warm-up increase correction coefficient, the warm-up increase conversion coefficient, and the start-time control correction coefficient. Performing the step of calculating the warm-up control time by calculating the product of the basic warm-up control time, the warm-up control time conversion coefficient, and the start-time control correction coefficient,
A fuel injection control method for an internal combustion engine. 2. The start-time control correction coefficient calculation map is created so as to change the start-time control correction coefficient only with respect to the engine temperature in a region where the intake air temperature is higher than the engine temperature. 3. The fuel injection control method for an internal combustion engine according to 2. At the start of the start of the internal combustion engine, after performing the initial injection for injecting fuel from the injector for the initial injection time, from the injector for the warm-up increasing injection time obtained by multiplying the basic injection time by the warm-up increasing correction coefficient. The warm-up increasing injection for injecting the fuel is performed while the warm-up increasing correction coefficient is attenuated as time elapses during the warm-up control time set by calculation, and after the warm-up control time has elapsed. A fuel injection control method for an internal combustion engine that shifts to injection control during steady operation,
During the warm-up control time, the temperature of the engine is monitored, and the increase ratio of the fuel injection amount in the warm-up increasing injection to the injection amount during the steady operation is set to a value corresponding to the temperature of the engine. Updating the initial value of the warm-up increase correction coefficient according to the temperature of the engine,
A fuel injection control method for an internal combustion engine. At the start of the start of the internal combustion engine, an initial injection control means for performing an initial injection for injecting a fuel of an injection amount determined by the initial injection time from the injector, and a warm-up increase obtained by multiplying the basic injection time by a warm-up increase correction coefficient. A fuel injection control device for an internal combustion engine, comprising: a warm-up fuel injection control means for performing a warm-up fuel injection for injecting fuel from the injector during the injection time for a warm-up control time set by calculation.
An engine temperature sensor for detecting a temperature of the internal combustion engine,
An intake air temperature sensor for detecting an intake air temperature of the internal combustion engine,
A startup control correction coefficient that indicates a larger value as the engine temperature is lower, shows a larger value as the intake air temperature is lower, and shows a larger value as the difference between the engine temperature and the intake air temperature is smaller, Map storage means for storing a three-dimensional start-time control correction coefficient calculation map used for calculating the engine temperature and the intake temperature detected by the engine temperature sensor and the intake temperature sensor, respectively;
A start-time control correction coefficient calculating means for calculating a start-time control correction coefficient by searching the map for the engine temperature and the intake air temperature;
The first injection control means calculates the first injection time by correcting a predetermined basic first injection time using the start control correction coefficient calculated by the start control correction coefficient calculation means. With means,
The warm-up increase injection control means corrects a predetermined basic warm-up increase correction coefficient using the start-time control correction coefficient calculated by the start-time control correction coefficient calculating means, thereby obtaining the warm-up increase correction coefficient. A warm-up increase correction coefficient initial value calculating means for calculating an initial value, and a predetermined basic warm-up control time corrected by using a start-time control correction coefficient calculated by the start-time control correction coefficient calculating means. Warm-up control time calculating means for calculating the warm-up control time,
A fuel injection control device for an internal combustion engine. Initial injection control means for performing an initial injection for injecting fuel from an injector for an initial injection time obtained by multiplying a predetermined basic initial injection time at the start of the internal combustion engine by a start time increase correction coefficient, and a basic injection time Is multiplied by a warm-up increase correction coefficient, the warm-up increase injection for injecting fuel from the injector during the warm-up increase injection time is calculated by multiplying the basic warm-up control time by the warm-up control time correction coefficient. During the engine control time, the fuel injection control device for an internal combustion engine, comprising: a warm-up increase injection control unit that performs the warm-up increase correction coefficient while attenuating the time-dependent increase coefficient with time.
An engine temperature sensor for detecting a temperature of the internal combustion engine,
An intake air temperature sensor for detecting an intake air temperature of the internal combustion engine,
The starting control correction coefficient indicates a larger value as the engine temperature is lower, a larger value as the intake air temperature is lower, and a larger value as the difference between the engine temperature and the intake air temperature is smaller, Map storage means for storing a three-dimensional start-time control correction coefficient calculation map used for calculating the engine temperature and the intake temperature detected by the engine temperature sensor and the intake temperature sensor, respectively;
Initial injection determination means for determining whether the first fuel injection performed at the start of the start of the internal combustion engine has been performed,
When the first injection determination unit determines that the first fuel injection has not been performed, a start control correction coefficient for calculating a start control correction coefficient by searching the map for the engine temperature and the intake air temperature. Coefficient calculating means,
The first injection control means is configured to calculate a start-up control correction coefficient at a predetermined basic first injection time when the first-injection determination means determines that the first fuel injection is not performed. An initial injection time calculating means for calculating the initial injection time by multiplying a control correction coefficient and a predetermined initial injection conversion coefficient,
The warm-up increase injection control means includes a warm-up increase conversion coefficient predetermined to a predetermined basic warm-up increase correction coefficient when it is determined that the first fuel injection is not performed by the first injection determination means, and A warm-up increase correction coefficient initial value calculating means for calculating an initial value of the warm-up increase correction coefficient by multiplying the start-time control correction coefficient calculated by the start-time control correction coefficient calculating means; When it is determined that the fuel injection is not being performed, a predetermined warm-up control time conversion coefficient and a start-time control correction coefficient calculated by the start-time control correction coefficient calculating means at a predetermined basic warm-up control time And a warm-up control time calculating means for calculating the warm-up control time by multiplying the warm-up control time by the first fuel injection determining means. A warm-up control time measuring means for starting the measurement of the warm-up control time calculated by the means; and an initial value of the warm-up increase correction coefficient while the warm-up control time measuring means is measuring the warm-up control time. A warm-up increase correction coefficient having a value exceeding 1 is calculated by multiplying the value by an elapsed time attenuation coefficient whose value changes with time, and the warm-up increase correction is performed when the warm-up control time has elapsed. A warm-up increase correction coefficient calculating means for setting the coefficient to 1;
A fuel injection control device for an internal combustion engine. At the start of the start of the internal combustion engine, an initial injection control means for performing an initial injection for injecting a fuel of an injection amount determined by the initial injection time from the injector, and a warm-up increase obtained by multiplying the basic injection time by a warm-up increase correction coefficient. A fuel injection control device for an internal combustion engine, comprising: a warm-up fuel injection control means for performing a warm-up fuel injection for injecting fuel from the injector during the injection time for a warm-up control time set by calculation.
The warm-up increasing injection control means,
Engine temperature monitoring means for monitoring the temperature of the engine during the warm-up control time,
The warm-up injection performed during the warm-up control time is performed according to the engine temperature such that the increase rate of the fuel injection amount to the injection amount during the steady operation is set to a value corresponding to the engine temperature. A warm-up increasing injection amount initial value updating means for updating an initial value of the boosting correction coefficient,
A fuel injection control device for an internal combustion engine, comprising:

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