JPH08303277A - Method for controlling asynchronous injection during acceleration - Google Patents

Abstract

PURPOSE: To improve drivability during acceleration by a method wherein a given period for fuel injection asynchronous with a suction stroke is set during acceleration and when acceleration is detected within the given period, fuel injection in a given time is prohibited. CONSTITUTION: At an electronic control device 6, an intake pressure signal (a) from an intake pressure sensor 13 and a number of revolutions signal Ne from a cam position sensor 14 form main information and a fundamental injection time is corrected by various correction factors to decide an injector final energizing time. Normally, fuel is injected from a fuel injection valve 5 at each crank angle in synchronism with an intake stroke. Meanwhile, when acceleration is detected, fuel is injected in asynchronism with a suction stroke based on an acceleration state but in this case, based on a crank angular velocity during injection of fuel, a given period for asynchronous injection is set. When acceleration is detected in the set given period, injection of fuel within a given time is prohibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling asynchronous injection during acceleration for controlling fuel injection during acceleration in a fuel injection system for injecting fuel in synchronism with an intake stroke in an automobile engine.

[0002]

2. Description of the Related Art Generally, in a synchronous injection type fuel injection control method for injecting fuel in synchronism with an intake stroke, there is a gap between the time at which the injected fuel amount is calculated and the time at which the fuel is injected at the calculated injection amount. During the transition, especially during acceleration, the air-fuel ratio may become lean due to the deviation. In order to compensate for such fluctuations in the air-fuel ratio, for example, as shown in Japanese Patent Laid-Open No. 5-214997, there is known a control method in which fuel is injected asynchronously in addition to synchronous injection during transition. . In such an asynchronous injection, in order to prevent the air-fuel ratio from becoming rich in a case where the asynchronous injection is performed twice consecutively due to continuous acceleration, a certain time has not elapsed from the previous asynchronous injection. The asynchronous injection prohibition period is set so that the asynchronous injection cannot be performed again (for example, Japanese Patent Laid-Open No. 64-73145). In such asynchronous injection, in order to prevent the air-fuel ratio at that time from becoming too rich, injection with different injection amounts is performed up to three times within a fixed time for one acceleration (FIG. 4). (A)).

[0003]

However, if the asynchronous injection is prohibited for a certain period of time (as indicated by the dotted line in FIG. 4 (b)) as described above, the air-fuel ratio becomes lean during the second acceleration. It may happen that proper acceleration cannot be performed. That is, if the asynchronous injection is performed up to three times for one acceleration and then the asynchronous injection is not performed until a certain time elapses, the cylinder with a lean air-fuel ratio may be obtained depending on the timing of the asynchronous injection in the intake stroke. Will occur. This is because if asynchronous is prohibited for a certain period of time, cylinders in which the intake stroke coincides with asynchronous injection and cylinders in which the intake stroke does not coincide with the number of revolutions occur, and when asynchronous injection is performed after the intake stroke, The air-fuel ratio may become lean without responding to acceleration in the cylinder. Therefore, proper acceleration may be hindered, and drivability may be deteriorated.

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

[0005]

In order to achieve the above object, the present invention takes the following measures. That is, the acceleration asynchronous injection control method according to the present invention injects fuel into each cylinder in an amount corresponding to the operating state of the engine for each predetermined crank angle in synchronization with the intake stroke,
In the asynchronous injection control method during acceleration in which fuel is injected asynchronously with the intake stroke based on the acceleration state when it is detected that the vehicle is accelerating, the asynchronous injection control method based on the crank angular velocity when the fuel is asynchronously injected It is characterized in that a predetermined period for injection is set, and when the acceleration time is detected within the set predetermined period, asynchronous injection of fuel within the predetermined period is prohibited.

[0006]

With such a structure, when the fuel is asynchronously injected, another asynchronous injection is prohibited within a predetermined period set based on the crank angular velocity at that time. In other words, the period during which the asynchronous injection is prohibited again is set based on the crank angular velocity at the previous asynchronous injection, so it differs depending on whether the engine speed is low or high. It will be compliant. Therefore, it is possible to prevent a problem that the prohibition period is too long in a certain operating state and the air-fuel ratio becomes lean before another asynchronous injection is performed. As a result, it is possible to prevent the drivability from being deteriorated due to the slow engine rotation.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

An engine 100 schematically shown in FIG. 1 has a three-cylinder structure for an automobile, and an intake system 1 thereof is provided with a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown), and the downstream thereof. The surge tank 3 is provided on the side. A fuel injection valve 5 is further provided in the vicinity of one end of the intake manifold 4 of the intake system 1 communicating with the surge tank 3, and this fuel injection valve 5 is connected to the electronic control unit 6
It is controlled by. The exhaust system 20 also includes
O ₂ sensor 21 for measuring oxygen concentration in exhaust gas
Is attached at a position upstream of the three-way catalyst 22 arranged in a pipe line leading to a muffler (not shown). This O
_{The 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 unit 8, an input interface 9 and an output interface 11, and the input interface 9 has Is the intake pressure signal a output from the intake pressure sensor 13 for detecting the pressure in the surge tank 3, the cylinder discrimination signal G1 output from the cam position sensor 14,
The crank angle reference signal G2 and the rotation speed signal Ne, the throttle opening signal d output from the throttle sensor 16 for detecting the open / closed state of the throttle valve 2, and the water temperature sensor 17 for detecting the cooling water temperature of the engine. The water temperature signal e, the voltage signal h output from the O ₂ sensor 21, and the like 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. Although not shown, the electronic control unit 6 is an A / D that converts analog signals such as the intake pressure signal a and the water temperature signal e into digital signals.
It is provided with a converter.

The electronic control unit 6 includes an intake pressure signal a output from the intake pressure sensor 13 and a cam position sensor 14.
The rotational speed signal Ne output from the main information is used as the main information, and the basic injection time is corrected by various correction factors determined according to the engine condition to determine the fuel injection valve opening time, that is, the injector final energization time T, and the determination thereof. The fuel injection valve 5 is controlled according to the supplied energization time, and fuel corresponding to the engine load is injected from the fuel injection valve 5 into the intake system 1 at a predetermined crank angle in synchronization with the intake stroke (synchronous injection). The program for is built in. The synchronous injection is performed once every two rotations of the crankshaft. In this program, when it is detected that the vehicle is accelerating, it is configured to inject fuel asynchronously with the intake stroke based on the acceleration state, and based on the crank angular velocity when fuel is asynchronously injected, A predetermined period for asynchronous injection is set, and when the acceleration time is detected within the set predetermined period, asynchronous injection of fuel within the predetermined period is prohibited.

The outline of this asynchronous injection control program during acceleration is as shown in FIG. However, as the program itself for calculating the effective injection time TAU in consideration of various correction factors and then calculating the injector final energization time T, a conventionally known program can be used, and therefore, illustration and description thereof will be omitted.

First, in step S1, the intake pressure PM that changes when the accelerator pedal is depressed to accelerate the vehicle.
The asynchronous injection time TIASYPM that determines the asynchronous injection amount is calculated from the change amount DPM of the. That is, since the intake pressure PM changes when the acceleration is performed, the change in the intake pressure PM is monitored to detect the acceleration, and the asynchronous injection time TIASYPM is calculated based on the change amount DPM at that time. In step S2, it is determined whether or not the asynchronous injection time TIASYPM is positive, and if it is a positive value, the process proceeds to step S3, and if it is 0 or less, another routine is entered. In step S3, it is determined whether or not the elapsed time counter C5ASYPM that elapses the elapsed time after the first asynchronous injection is performed is less than or equal to the prohibition time TASYGR that is the set predetermined period. Go to S4,
If it exceeds, the process proceeds to step S6. In step S4, it is determined whether the prohibition time TASYGR is set and the number of asynchronous injections NTASY after that is one.
If it is, the process proceeds to step S8, and if not, the process proceeds to step S5. In step S5, it is determined whether or not the number of asynchronous injections NTASY is 2, and 2
If it is the number of times, the process proceeds to step S10, and if not, the process proceeds to another routine.

At step S6, the number of asynchronous injections NTA
SY is set to 1 and the elapsed time counter C5ASYPM is reset (= 0). In step S7, the prohibited time TAS
Calculate YGR. In this embodiment, the prohibition time TASY
Since the engine has three cylinders, GR is set by multiplying the rotation time T240 required to rotate the crank angle by 240 ° CA by a coefficient KPMASY. Coefficient KPMAS
Y is set to 6, for example. That is, the crankshaft is 4
The rotation time T240 and the coefficient KPMASY are set so that the rotation time becomes the prohibition time TASYGR. In step S8, the asynchronous injection time TIASYPM
Is newly set to 1/2 of the value obtained by calculating.
In step S9, the asynchronous injection number NTASY is set to 2. In step S10, the asynchronous injection time TIAS
A new value is set to 1/4 of the value obtained by calculating YPM. In step S11, the number of asynchronous injections NTASY
Is set to 3. In step S12, the injection routine is executed. In the case of an engine other than the three-cylinder engine, for example, a four-cylinder engine, the rotation time is 18
The time required to rotate 0 ° CA may be used. In this case, the coefficient KPMASY may be set to 8.

A case where acceleration is executed in such a configuration will be described. Intake pressure PM when acceleration is performed
Changes, the asynchronous injection time TIASYPM is calculated. That is, the control is step S1 →
Go to S2 → S3. Since at least the prohibition time TASYGR has elapsed since acceleration was performed before this time, the elapsed time counter C5ASYPM indicates the prohibition time TASYGR.
It keeps time over SYGR. Therefore, the control thereafter proceeds to steps S6 → S7 → S12, sets the inhibition time TASYGR at that time, and executes the first asynchronous injection. After that, when the acceleration is continued and the intake pressure PM changes, the control proceeds to steps S1 → S2 → S3. At this point in time, the elapsed time counter C5ASYPM is reset when the first asynchronous injection is executed, so the count value of the elapsed time counter C5ASYPM is smaller than the inhibition time TASYGR. Since the asynchronous injection number NTASY is set to 1, the control is
Then, it progresses to step S4->S8->S9-> S12 and performs the 2nd asynchronous injection.

If the acceleration is completed up to this point, that is, if the asynchronous injection time TIASYPM calculated based on the change amount DPM is 0 or less even if the intake pressure PM changes, the control is performed in step S1 → The routine proceeds to S2 and shifts to another routine. On the other hand, the acceleration continues and the intake pressure P
If M has changed, control is performed in steps S1 → S2.
→ S3 → S4. Since the asynchronous injection number NTASY is set to 2 when the second asynchronous injection is executed, the control is further performed in steps S5 → S10 → S1.
The process proceeds from 1 to S12 and the third asynchronous injection is executed. When the acceleration is continuously performed, the asynchronous injection is continuously performed up to three times in this way. In this case, the asynchronous injection amount, in other words, the asynchronous injection time TIASYPM becomes shorter as it becomes the second and third times, thereby preventing the air-fuel ratio from becoming overrich.

Then, if the acceleration is further continued, or if the acceleration is once stopped but immediately thereafter again, the asynchronous injection number NTASY is performed.
Has exceeded 3 times, or the elapsed time counter C5A
Since the count value of SYPM, that is, the elapsed time after the execution of the first asynchronous injection is within the inhibition time TASYGR, the synchronous injection is not executed. That is, when the acceleration is stopped, when the asynchronous injection time TIASYPM is calculated based on the change amount DPM of the intake pressure PM, the value becomes 0 or less. Therefore, the control proceeds from step S1 to S2 to another routine, and the asynchronous injection is not executed. If the acceleration is continued and the time has not passed the prohibition time TASYGR set at the time of the first asynchronous injection, the asynchronous injection number NTASY is set to 3, so the control is , Steps S1 → S2 → S3 → S4 → S5 →
The process proceeds to another routine, and the asynchronous injection is not executed.

As described above, the asynchronous injection is performed three times for one acceleration, but the inhibition time T from the first asynchronous injection.
If ASYGR does not elapse, the asynchronous injection for the second acceleration is not executed. That is, as shown in FIG.
When the first asynchronous injection is executed almost immediately after the synchronous injection performed in accordance with the intake stroke of cylinder A, asynchronous injection requires the asynchronous injection in the next intake stroke of cylinder A because the fuel by the asynchronous injection exists. There is no. Since the next intake stroke is within the prohibition time TASYGR, the asynchronous injection is not executed. On the other hand, at the time of the second intake stroke of the cylinder A after the asynchronous injection is executed, the asynchronously injected fuel is consumed in the previous intake stroke, so that the asynchronous injection is performed when the acceleration is performed. There is a need to do. In this embodiment, the prohibition time TASYGR is set by multiplying the rotation time T240 required for the crank angle to rotate by 240 ° CA by a coefficient KPMASY of 6, so that the second intake of the cylinder A after the asynchronous injection is performed. Prohibition time T in the process
Exceeds ASYGR. Therefore, when the acceleration is performed, the asynchronous injection is accordingly performed up to three times in the accelerated state. As a result, it is possible to prevent the occurrence of a problem in which the air-fuel ratio becomes excessively rich in a certain cylinder, or the air-fuel ratio becomes lean without performing asynchronous injection even though re-acceleration is performed and the acceleration does not shift to proper acceleration. be able to.

The present invention is not limited to the above-described embodiment, but acceleration may be detected by a change in intake pressure, or may be detected by a change in throttle opening, for example.

In the above embodiment, the rotation time T240 required for the crank angle to rotate by 240 ° CA.
Although the prohibition time TASYGR is set based on the above, the prohibition time may be set based on the time until the cylinder discrimination signal G1 is counted a predetermined number of times, for example, 6 times.

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

[0021]

As described above in detail, the present invention sets the predetermined period during which the asynchronous injection is prohibited based on the crank angular velocity at that time, so that the influence of the asynchronous injection disappears regardless of the engine speed. It is possible to set a minimum period of, and to prohibit the asynchronous injection again. Therefore, it is possible to prevent the problem that the air-fuel ratio becomes lean before performing the asynchronous injection again.
It is possible to prevent the drivability from being deteriorated due to the rattling of the engine rotation.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an embodiment of the present invention.

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

FIG. 3 is an operation explanatory view of the same embodiment.

FIG. 4 is an explanatory view of the operation of a conventional example.

[Explanation of symbols]

 1 ... Intake system 2 ... Throttle valve 4 ... Intake manifold 5 ... Fuel injection valve 6 ... Electronic control unit 7 ... Central processing unit 8 ... Memory device 9 ... Input interface 11 ... Output interface

Claims (1)

[Claims] 1. A fuel is injected into each cylinder in an amount corresponding to the operating condition of the engine at every predetermined crank angle in synchronization with the intake stroke, and when the acceleration is detected, the fuel is brought into the accelerated condition. Based on the asynchronous injection control method during acceleration, in which fuel is injected asynchronously with the intake stroke, a predetermined period for the asynchronous injection is set based on the crank angular velocity when the fuel is injected asynchronously, and within the set predetermined period A method for controlling asynchronous injection during acceleration, characterized in that, when the time of acceleration is detected, asynchronous injection of fuel is prohibited within the predetermined period.