JPH09189254A - Asynchronous injection controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an air-fuel ratio from being turned into rich caused by the lowering of intake air density when racing is performed on a high land. SOLUTION: In an asynchronous injection controlling method in which a fuel amount according to engine operating conditions is synchronously injected to each air cylinder per predetermined crank angle by being synchronized with an intake stoke, and fuel is injected at a plurality of different timings by being asynchronized with the intake stoke, atmospheric pressure is detected, and when the detected atmospheric pressure is lower than a set predetermined value, such a state is detected that the pressure change of an intake pipe is generated when an engine is shifted from idle operation to non-idle operation, and such a state is prohibited that fuel is prohibited to be asynchronously injected at a first timing when the engine is shifted to the non-idle operation condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an asynchronous injection control method for controlling fuel injection during acceleration in a fuel injection system in which fuel is injected in synchronization 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 a change in the air-fuel ratio, as shown in, for example, Japanese Patent Laid-Open No. 5-214997, control is performed so that fuel is injected asynchronously in addition to synchronous injection during a transition in which the intake pipe pressure changes. It has been known. In such an asynchronous injection, for example, when racing is performed during idle operation, the first asynchronous injection is executed at the end of idle operation in order to prevent the air-fuel ratio from becoming lean, and then, Asynchronous injection corresponding to a change in intake pipe pressure is performed, transient air-fuel ratio correction is performed in synchronous injection, and control is performed so that the air-fuel ratio changes to the rich side. That is, by changing the intake pipe pressure from the idle operation state by racing, the asynchronous injection is continuously executed, and the increase correction is also performed in the synchronous injection.

[0003]

By the way, in a vehicle equipped with an automatic transmission, a so-called D-range chip in-racing is used in which the accelerator pedal is operated only slightly while traveling to a high altitude and shifting the automatic transmission to the D range. May be carried out. In this case, the intake air density is reduced due to the high altitude, and therefore the intake air amount is insufficient, and as shown in FIG. 3, after the idle operation is turned off, that is, the throttle valve is opened slightly larger than the idle opening degree. After performing the asynchronous injection, the asynchronous injection with respect to the change of the intake pipe pressure, and the increase correction of the synchronous injection by the transient air-fuel ratio correction, the air-fuel ratio may temporarily become overrich. As a result, the engine rotation may decrease (indicated by the dotted line in FIG. 3) and the operating state may become unstable.

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 asynchronous injection control method according to the present invention synchronously injects into each cylinder the amount of fuel corresponding to the operating state of the engine for each predetermined crank angle in synchronization with the intake stroke, and asynchronously with the intake stroke. In the asynchronous injection control method in which fuel is injected multiple times at different timings, atmospheric pressure is detected,
When the detected atmospheric pressure is lower than the set predetermined value, it is detected that a change in intake pipe pressure has occurred at the time of transition from idle operation to non-idle operation, and at the first timing when transitioning to the non-idle operation state. The prohibition of injecting fuel asynchronously is prohibited.

With such a configuration, when racing or the like is performed during idle driving in a high altitude where the atmospheric pressure is lower than a set predetermined value, the idle operation is switched to the non-idle operation. However, since the fuel is not injected asynchronously at the initial timing during the transition, that is, during the transition, the increase in the fuel injection amount is less than the increase in the normal asynchronous injection. Therefore, even if the atmospheric pressure is low and the intake air density is low, the fuel injection amount to be increased is small, and therefore the intake air amount does not become insufficient. Therefore, the air-fuel ratio does not change to the rich side, and it is possible to prevent the engine rotation from decreasing.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention detects that the accelerator pedal has been operated to change from the idle operation to the non-idle operation state when the idle operation is performed in a place where the atmospheric pressure such as highland is lower than the levelland. , The atmospheric pressure at that time is lower than a predetermined value, it is determined that the altitude is high, and the asynchronous fuel injection is prohibited at the first timing to suppress the enrichment of the air-fuel ratio due to the asynchronous fuel injection. This is to prevent the rotation from decreasing.

[0008]

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 is connected to an automatic transmission (not shown). The intake system 1 is provided with a throttle valve 2 that opens and closes in response to an accelerator pedal (not shown), and a surge tank 3 is provided downstream thereof. 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 adjacent to the intake valve 31.
Are controlled by the electronic control unit 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 arranged in a pipe line leading to a muffler (not shown). There is. The 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 unit 8, an input interface 9 and an output interface 11. 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 position signal c output from the shift position sensor 15 for detecting that the automatic transmission is shifted to the D range (running range), and the opening / closing state of the throttle valve 2. The throttle opening signal d output from the throttle sensor 16 for detecting the temperature, the water temperature signal e output from the water temperature sensor 17 for detecting the cooling water temperature of the engine 100, and the voltage output from the O ₂ sensor 21 described above. The signal h or the like is input. On the other hand, the output interface 11
From the above, the fuel injection signal f is output to the fuel injection valve 5, and the ignition pulse g is output to the spark plug 18. Although not shown, the electronic control unit 6 includes an A / D converter that converts analog signals such as the intake pressure signal a and the water temperature signal e into digital signals.

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, in synchronization with the intake stroke, fuel is injected into each cylinder synchronously at a predetermined crank angle in accordance with the operating state of the engine 100, and fuel is injected a plurality of times asynchronously with the intake stroke. In this case, the atmospheric pressure is detected, and when the detected atmospheric pressure is lower than the set predetermined value, it is detected that a change in intake pressure has occurred at the transition from idle operation to non-idle operation. It is configured to prohibit asynchronous fuel injection at the first timing when the operation state is entered. In the asynchronous injection, when the idle operation state, that is, the idle on state is changed to the non-idle operation state, that is, the idle off state by performing racing, for example, after the transition, the idle O
The asynchronous injection at the time of N / OFF is first performed, and then the asynchronous injection at the time of change in the intake pipe pressure corresponding to the change in the intake pressure PM is performed, for example, in three times. Furthermore, since the electronic control unit 6 determines that the transition time is in transition due to the change in the intake pressure PM, when calculating the effective injection time TAU in the case of the synchronous injection, the internal wall surface of the intake system 1 in the vicinity of the intake valve 31 is calculated. The transient air-fuel ratio correction amount TPWET is increased based on the wall surface deposition rate of the adhering fuel and the fuel evaporation time constant.

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

First, in step S1, it is detected from the throttle opening signal d from the throttle sensor 16 that the throttle valve 16 has been opened from idle on to shift to a non-idle operation state idle off which is not an idle operation state. In step S2, the engine speed N
It is determined whether E is a predetermined value or less. In step S3,
It is determined whether the atmospheric pressure detected by the intake pressure sensor 13 is lower than a predetermined value. The atmospheric pressure detection by the intake pressure sensor 13 detects the pressure value when the throttle valve 2 is fully opened while the electronic control unit 6 is powered on,
The detected pressure value may be applied as the atmospheric pressure. The predetermined value may be set in correspondence with the atmospheric pressure in the highlands, which reduces the intake air density and affects the intake air amount during idle operation. In step S4, it is determined from the position signal c from the shift position sensor 15 whether the automatic transmission is switched to the D range. In step S5, the asynchronous injection first performed in the idle-off state, that is, idle ON / OFF
Asynchronous injection is prohibited. In step S6, asynchronous injections with different timings are carried out.

In such a structure, when racing is performed while the vehicle is stopped on a level ground and is in idle operation, the throttle valve 2 opens from the opening during accelerator operation, so idle operation is changed to non-idle operation. To do. In this case, if the engine speed NE exceeds the predetermined value, the control proceeds to steps S1 → S2 → S6, and the engine speed NE is equal to or lower than the predetermined value but the atmospheric pressure is flat. Therefore, if it exceeds the specified value,
The control proceeds in steps S1 → S2 → S3 → S6, and performs normal asynchronous injection of idle ON / OFF asynchronous injection and intake pipe pressure asynchronous injection, respectively. Furthermore, when racing is performed during idle operation on level ground, the engine speed NE is below a predetermined value, and the atmospheric pressure is below a predetermined value due to passage of a low pressure, for example.
When the shift position is not in the D range, that is, when the shift position is in the P range or the N range, the control is performed in steps S1 → S2 → S3 → S4 → S.
The process proceeds to 6 and the normal asynchronous injection is performed in the same manner. In these cases, the fuel injection amount of the synchronous injection is increased and corrected by the transient air-fuel ratio correction amount TPWET.

Next, a case will be described in which racing is performed during idle driving in a highland. When the racing is relatively large and the engine speed NE rises above the predetermined value, the control proceeds to steps S1 → S2 → S6 even in the highland, and the normal asynchronous injection is performed. Also, even when the engine speed NE is a small racing below a predetermined value, when the shift position is not in the D range, the control is performed in steps S1 → S2 → S.
The process proceeds from 3 to S4 to S6, and the normal asynchronous injection is performed without prohibiting the asynchronous injection during idle ON / OFF.
On the contrary, when the so-called D-range chip inlacing is performed with the shift position in the D range, the engine speed NE does not rise to a level higher than a predetermined value, and therefore the control is performed in steps S1 → S2 → S3. → S4 →
Idle O to be executed first in the asynchronous injection, proceeding to S5
The asynchronous injection at the time of N / OFF is prohibited and not executed, and the asynchronous injection at the timing of the intake pipe pressure change which is the asynchronous injection at the next timing is executed as the first asynchronous injection at this time.
In this case, in the synchronous injection, the fuel injection amount is increased and corrected by the transient air-fuel ratio correction amount TPWET as in the normal transient time.

Therefore, when such a D-range chip inlacing is carried out, the intake pressure PM changes, but it is not a level that can be recognized as a normal transient time. In consideration of the above, the fuel injection amount is increased only by the asynchronous injection when the intake pipe pressure changes, without performing only the idle ON / OFF asynchronous injection executed at the first timing of the asynchronous injection. Therefore, the amount of fuel to be increased is smaller than the asynchronous fuel injection amount when it is determined to be a normal transient time, so the air-fuel ratio does not shift to the rich side, and the asynchronous injection at the time of intake pipe pressure change is Since it is carried out, it is possible to prevent the air-fuel ratio from fluctuating without being biased to the lean side. Therefore, the engine speed does not drop,
Can maintain a stable state.

The present invention is not limited to the embodiment described above. In the above embodiment, the atmospheric pressure is detected by the intake pressure sensor 13 when the throttle valve 2 is fully opened. However, the pressure introduced into the intake pressure sensor 13 is switched between the atmospheric pressure and the intake pressure. It may be. In addition to the intake pressure sensor 13, a pressure sensor for atmospheric pressure may be provided.

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]

As described above, according to the present invention, when the vehicle is driven in a low atmospheric pressure, for example, in a highland, when racing or the like is performed in the idle operation state, the idle operation shifts to the non-idle operation. Since the fuel is not injected asynchronously at the first timing during the transition, the fuel injection amount to be increased is smaller than that in the case of normal asynchronous injection control, and the atmospheric pressure is low and the intake air density is low. However, the intake air amount does not become insufficient, and the air-fuel ratio can be efficiently prevented from becoming rich. Therefore,
It is possible to prevent the engine rotation from decreasing due to the air-fuel ratio changing to the rich side.

[Brief description of the 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 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 synchronously into each cylinder in an amount corresponding to an operating state of an engine at each predetermined crank angle in synchronization with an intake stroke, and the fuel is injected a plurality of times asynchronously with the intake stroke. In the asynchronous injection control method of injecting, the atmospheric pressure is detected, and when the detected atmospheric pressure is lower than the set predetermined value, it is detected that the change in the intake pipe pressure has occurred at the transition from the idle operation to the non-idle operation. , Asynchronous injection control method characterized by prohibiting prohibiting asynchronous injection of fuel at the first timing when transitioning to a non-idle operation state.