JP3046475B2 - Starting fuel control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting fuel control method for an automobile engine.

[0002]

2. Description of the Related Art In a fuel injection type engine, the required amount of fuel at startup is generally higher as the temperature of the engine is lower. Usually, the temperature of the engine is detected by measuring the temperature of the cooling water of the engine, and using the temperature of the cooling water,
The corresponding start-up fuel injection amount is determined by interpolation from a preset map to control the start-up fuel supply.
Under such basic fuel control, various starting fuel controls have been considered in order to eliminate problems at the time of restart. For example, as described in Japanese Patent Application Laid-Open No. 5-5439, when the engine is operated at high speed, stopped, and restarted after being left, the combustion chamber is temporarily damaged by the fuel adhering to the inner wall of the intake pipe during operation. Since the engine may become over-rich, the elapsed time after stopping the engine is detected, it is determined that the elapsed time is within a predetermined time limited by upper and lower limits, and the fuel injection amount at the time of restart is reduced. There are also known corrections.

[0003]

By the way, when the engine is started at cryogenic temperature, about 30 to 60 seconds later, the engine is stopped to leave the car due to, for example, lost objects, and then immediately restarted. In the vicinity of the combustion chamber of the engine, the temperature of the engine locally increases, but the temperature of the cooling water hardly increases. For this reason, when the starting fuel injection amount is determined according to the cooling water temperature as described above, the difference between the starting fuel injection amount and the starting fuel injection amount actually required by the combustion chamber is determined. This may cause poor starting due to over-rich. Also,
When the fuel injection amount at the time of restart is reduced according to the elapsed time after stopping the engine as in the above publication, a lean tendency may occur in some cases.

An object of the present invention is to solve such a problem.

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the start-time fuel control method according to the present invention, in the start-time fuel control method that determines the start-time fuel injection amount according to the temperature of the engine coolant, detects the temperature of the engine coolant at the start, Measure the operating time at least from the start of the operation and the start of the operation until the ignition is stopped and the operation is forcibly terminated.At the time of restart, the measured previous operation time is shorter than the set time, In addition , when it is detected that the temperature of the previous cooling water detected is lower than the temperature of the current cooling water, the fuel injection amount at the time of starting is reduced according to the previous operation time and the temperature of the previous cooling water. Features.

[0006]

With such a configuration, at the time of restart, particularly at the time of restart in an extremely low temperature environment, the previous operation time measured is shorter than the set time, and the temperature of the last detected coolant is detected. When the temperature is lower than the temperature of the cooling water this time, the fuel injection amount at the time of starting is reduced, so that the fuel injection amount is in accordance with the temperature in the vicinity including the combustion chamber, and the startability is not deteriorated. That is, when only a short time has elapsed since the end of the previous operation, the temperature of the combustion chamber and the vicinity thereof has not decreased. Although the fuel injection amount becomes excessive, the fuel injection amount at the time of starting is reduced according to the previous operation time and the temperature of the previous cooling water. Therefore,
A good restart can be achieved without deteriorating the startability at the time of restart.

[0007]

An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 schematically shown in FIG. 1 is for an automobile, and its intake system 1 is provided with a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown). A tank 3 is provided.
Intake manifold 4 of intake system 1 communicating with surge tank 3
A fuel injection valve 5 is further provided near one end of the fuel injection valve 5, and the fuel injection valve 5 is controlled by an electronic control device 6. Further, an O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas is attached to the exhaust system 20 at a position upstream of a three-way catalyst 22 provided in a pipe leading to a muffler (not shown). I have. This O ₂ sensor 21
Outputs a voltage signal h corresponding to the oxygen concentration.

The electronic control unit 6 is mainly composed of a microcomputer system including a central processing unit 7, a storage device 8, an input interface 9, and an output interface 11. The storage device 8 includes at least a ROM that stores programs and various data that is not changed, a RAM that stores temporary data, and a backup RAM that stores data even when power to the electronic control device 6 is not supplied. . The input interface 9 has an intake pressure signal a output from an intake pressure sensor 13 for detecting the pressure in the surge tank 3 and an output from a rotational speed sensor 14 for detecting the engine rotational speed NE. A rotation speed signal b, a vehicle speed signal c output from a vehicle speed sensor 15 for detecting the vehicle speed, a throttle opening signal d output from a throttle sensor 16 for detecting the open / closed state of the throttle valve 2, a cooling of the engine 100 Water temperature sensor 17 for detecting water temperature
A water temperature signal e output from, such as a voltage signal h output from the O ₂ sensor 21 as described above are input. On the other hand, the output interface 11 outputs a fuel injection signal f to the fuel injection valve 5 and an ignition pulse g to the spark plug 18.

The electronic control unit 6 uses the intake pressure signal a output from the intake pressure sensor 13 and the rotational speed signal b output from the rotational speed sensor 14 as main information,
The basic injection time is corrected by various correction coefficients determined according to the operating state of the fuel injection valve to determine the fuel injection valve opening time, that is, the injector final energization time T, and the fuel injection valve 5 is controlled by the determined energization time, A program for injecting fuel corresponding to the engine load from the fuel injection valve 5 to the intake system 1 is stored. In this program, at the time of starting, the temperature of the cooling water of the engine at the time of starting is detected, and after the engine is started and the operation is started, at least the operation time until ignition is stopped and the operation is forcibly terminated is started. measured, upon restart, when shorter than the time that the last operating time measured is set, and the temperature of the cooling water detected last time is detected to be lower than the temperature of this cooling water, the last The fuel injection amount at the time of starting is reduced in accordance with the operating time of the engine and the temperature of the previous cooling water. Engine 1 accompanying this program
Basic start-up fuel injection amount TAU corresponding to 00 coolant temperature
STA _B is set in the map M1 and stored in the storage device 8. Further, correction coefficients α and β for correcting the basic start-time fuel injection amount TAUSTA determined when calculating the start-time fuel injection amount at the time of restarting are mapped to maps M2 and M3, respectively.
And is stored in the storage device 8. As shown in FIG. 3, the correction coefficient α is set such that the maximum value is 1 and the minimum value is 0.
The correction coefficient β is set so that it becomes smaller as the cooling water temperature at the start increases, and the correction coefficient β becomes smaller as the previous operation time becomes longer, with the maximum value being 1 and the minimum value being 0. At 15 ° C. or higher, the correction coefficient α is set to 0 so that the fuel injection amount at the start is corrected only at an extremely low temperature.

The outline of the starting fuel control program is as shown in FIG.

First, at step S 1, a coolant temperature THW ₂ of the engine 100 at the time of starting is detected from a coolant temperature signal e output from the coolant temperature sensor 17. In step S2,
The map M1, sets the basic start time fuel injection amount TAUSTA _B corresponding to the detected coolant temperature THW _2. In this case, since only the basic fuel injection amount at the start TAUSTA corresponding to the representative cooling water temperature is set in the map M1, the other cooling water temperatures are obtained by interpolation calculation. In step S3, it detected during the previous startup, is stored in the backup RAM of the storage device 8 and reads the cooling water temperature THW ₁ and the previous operating time T _1. In step S4, obtaining the α correction coefficient corresponding to the read coolant temperature THW ₁ from the map M2. In step S5,
Step S4 Similarly, obtaining the β correction coefficient corresponding to the previous operation time T ₁ from the map M3. In step S6,
The cooling water temperature THW ₂ detected this time is the previous cooling water temperature THW.
_It is determined whether it is higher than ₁ or not.
The process proceeds to step S8 if it is low.

In step S7, the starting fuel injection amount at the time of the present start is reduced from the basic start fuel injection amount TAUSTA _B by the basic starting fuel injection amount TAUTSA _B and the correction coefficients α and β. Quantity TAUST
A is calculated by the following equation.

TAUSTA = TAUSTA _B × (1−αβ) In step S8, the starting fuel injection amount T at the time of this start is set.
AUSTA is determined as the basic start-time fuel injection amount TAUTSA _B. In step S9, the correction coefficients α and β obtained in steps S4 and S5 are set as initial values, and are attenuated from the initial values until they become 0 at a constant rate with the passage of time. return. In step S10, it determines whether longer than the current time T _{A FTS} the elapsed time T ₂ is set after startup is longer, the process proceeds to step S11, if it is shorter returns to the subroutine.
In step S11, the coolant temperature THW ₂ and the elapsed time _{T 2} that has been detected this time, (stores) written in the backup RAM of the memory device 8 in place of the previous coolant temperature HTW ₁ and operating time _{T 1.}

In such a configuration, for example, when the temperature is-
When the temperature is around 20 ° C., the engine 100 is started once and
If the operation is stopped for about 0 seconds and then the ignition key is operated and restarted after a while, the cooling water temperature rises only slightly because the operation time is short. If the time interval until the restart is short, the cooling water temperature at the restart does not drop, but is slightly higher than the cooling water temperature THW1 at the time of the previous start. This way, the restart is performed, control proceeds to step S1 to S6, the cooling water temperature THW ₂ that are detected during the current start is higher than the cooling water temperature THW1 of the previous start-up step S7 →
The process proceeds from step S9 to step S10. If the elapsed time T2 after the start is longer than the set time T _AFTS , the process proceeds to step S11. In this case, in the previous operation for about one minute, the temperature of the cooling water slightly increased, but the temperature in the vicinity including the combustion chamber was high, and the correction coefficient α,
Since the start-time fuel injection amount TAUSTA is reduced by β, the fuel injection amount does not become over-rich. Therefore, even at the time of restart, the engine can be started satisfactorily without deteriorating the startability.

If a long time has elapsed since the previous operation of the engine, for example, the operation of the engine has been stopped from before noon to the evening, and if the cooling water temperature has fallen sufficiently, the start of the current engine since the coolant temperature THW ₂ lower than the previous cooling water temperature THW _1, control, step S1~
Proceeds to step S6, then executes step S8, and determines a start timing fuel injection amount TAUSTA in accordance with the coolant temperature THW ₂ that are detected during the current start, if the elapsed time T2 after starting is constant over , Step S10 → Step S
The process proceeds to 11, and the reduction of the starting fuel injection amount TAUSTA is prohibited. That is, in this case, the starting fuel injection amount T
AUSTA is not reduced and the engine can be started well without becoming lean.

The present invention is not limited to the embodiment described above. For example, the correction coefficient α and the correction coefficient β are set to values that can calculate the starting fuel injection amount TAUSTA at that time by subtracting a set value from the starting fuel injection amount TAUSTA _B. Is also good.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0019]

According to the present invention, as described in detail above, the starting fuel injection amount according to the cooling water temperature at the time of restart is shorter than the set operation time before restart, If the temperature of the cooling water at that time is lower than the temperature of the current cooling water, the fuel is reduced based on the operating time of the engine and the temperature of the cooling water at that time. Volume, and therefore the temperature of the cooling water is low, however, the restartability in a state where the temperature of the combustion chamber and its vicinity is high by the previous start, and the startability in the normal cold start are deteriorated. Without any improvement.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is a configuration explanatory view schematically showing a map configuration of correction coefficients α and β of the embodiment.

[Explanation of symbols]

 5: Fuel injection valve 6: Electronic control unit 7: Central processing unit 8: Storage unit 9: Input interface 11: Output interface 17: Water temperature sensor

Claims (1)

(57) [Claims] 1. A starting fuel control method for determining a starting fuel injection amount in accordance with a temperature of an engine cooling water, comprising: detecting a temperature of an engine cooling water at a starting time; Measure at least the operation time from when the ignition is stopped until the operation is compulsorily terminated.When restarting, the measured previous operation time is shorter than the set time and the detected previous cooling water if the temperature detected is lower than the temperature of this cooling water, starting fuel control method characterized by weight loss of the starting time fuel injection quantity according to the temperature of the previous operating time and the last cooling water .