JPH0988702A - Fuel injection controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent drivability from spoiling even in a case of cutting or decreasing of fuel for preventing overspeed or overheat in an ordinary driving condition. SOLUTION: A basic fuel injection quantity is decided based on an internal combustion engine speed and an internal combustion load detected by a throttle sensor 126. When an internal combustion engine atmosphere temperature detected by a cooling water temperature sensor 114 becomes a prescribed threshold temperature TTH or more, a fuel reduction coefficient KTHW and the minimum fuel injection QHOT in high temperature are decided as a function of the engine speed detected by an engine speed sensor incorporated in a distributer 112. And it is decided that this fuel injection quantity gradually decreases toward the injection quantity QHOT at high temperature according to the internal combustion engine atmosphere temperature. Abrupt decreases in the fuel and the torque are thus suppressed and the drivability can be prevented from deteriorating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device capable of suppressing abrupt torque fluctuations when a fuel cut is performed.

[0002]

2. Description of the Related Art Conventionally, when an internal combustion engine is in a low load / high speed operation state, the fuel to be supplied to the internal combustion engine is shut off in order to prevent the internal combustion engine from becoming overspeed or overheated. An electronic fuel injection control device that performs so-called fuel cut is already known (for example, JP-A-63-14).
7950 publication).

That is, the electronic fuel injection control device according to the above-mentioned proposal reliably prevents over-rotation or over-heating of the internal combustion engine even when the ambient temperature changes significantly or when the temperature of the exhaust system cannot be accurately measured. Therefore, when the ambient temperature is equal to or higher than a predetermined temperature and the internal combustion engine speed is equal to or higher than a predetermined speed for a predetermined time, the fuel is cut or the fuel is reduced.

[0004]

However, although the electronic fuel injection control device according to the above-mentioned proposal can prevent over-rotation or over-heating in an operating state in which the internal-combustion engine speed or the internal-combustion engine temperature is high, fuel cut is performed. Alternatively, it is unavoidable that the torque is sharply reduced and the drivability is deteriorated when the fuel is reduced.

The present invention has been made in view of the above problems, and a fuel that does not impair drivability even when a fuel cut or fuel reduction is performed in order to prevent excessive rotation or overheating in a normal operating state. An object is to provide an injection control device.

[0006]

According to the fuel injection control apparatus of the present invention, the basic fuel injection based on the detecting means for detecting the operating state of the internal combustion engine and the operating state of the internal combustion engine detected by the detecting means. The basic fuel injection amount calculating means for calculating the amount, the atmosphere temperature detecting means for detecting the atmosphere temperature of the internal combustion engine, and the atmosphere temperature of the internal combustion engine detected by the atmosphere temperature detecting means have become equal to or higher than a predetermined temperature. Sometimes a high temperature minimum fuel injection amount calculation means for calculating a high temperature minimum fuel injection amount necessary for maintaining the rotation of the internal combustion engine while preventing over-rotation or overheating of the internal combustion engine,
Current fuel injection amount Update fuel injection for calculating the update fuel injection amount based on the minimum fuel injection amount at high temperature calculated by the minimum fuel injection amount at high temperature and the ambient temperature of the internal combustion engine detected by the ambient temperature detecting device Execution fuel injection amount calculated as the execution fuel injection amount, whichever is smaller between the amount calculation device, the basic fuel injection amount calculated by the basic fuel injection amount calculation device, and the update fuel injection amount calculated by the update fuel injection amount calculation device. And a calculating means.

In the fuel injection control device according to the present invention, when the ambient temperature of the internal combustion engine becomes equal to or higher than a predetermined temperature, the basic fuel injection amount, the excessive rotation or overheating of the internal combustion engine is prevented, and the internal combustion engine is rotated. The execution fuel injection amount is determined based on the minimum high temperature fuel injection amount and the ambient temperature required to maintain the temperature.

[0008]

1 is a block diagram of an embodiment of a fuel injection control apparatus according to the present invention, in which one cylinder 11 of an internal combustion engine is provided with an air cleaner 121, an intake pipe 122 and an intake valve 123. Intake air is supplied. Intake valve 12
A fuel injection valve 124 is installed on the upstream side of 3 to inject fuel into the intake air to supply the fuel into the cylinder 11 as an air-fuel mixture. Further, a throttle valve 125 is provided in the middle of the intake pipe 122.
Is installed to adjust the amount of intake air taken into the cylinder 11.

The air-fuel mixture sucked into the cylinder 11 is the spark plug 1
It is ignited by 11 and explodes to generate a driving force. Then, the exhaust gas is discharged to the outside via the exhaust pipe 131 and the purifying device 132. The fuel injection amount to the cylinder is adjusted by controlling the opening time of the fuel injection valve 124 by the ECU 14 which is a microcomputer system.

The ECU 14 includes a bus 141 and a CPU 14.
2, a memory 143, an input interface 144 and an output interface 145. The operating state of the internal combustion engine is attached to a throttle sensor 126 that detects the opening of the throttle valve 125, a rotation speed sensor (not shown) built in the distributor 112 that supplies an ignition signal to the spark plug 111, and an exhaust pipe 131. O
_It is detected by the ₂ sensor 133 and taken into the ECU 14 via the input interface 144.

Further, the intake pipe 12 downstream of the air cleaner 121.
2, the intake air temperature detected by the intake air temperature sensor 127, the cooling water temperature detected by the water temperature sensor 114 attached to the water jacket of the cylinder 11, and the exhaust temperature sensor 133 attached to the purification device 132. The exhaust gas temperature is also taken into the ECU 14 via the input interface 144 and used for determining the ambient temperature of the internal combustion engine. In the examples below,
The ambient temperature of the internal combustion engine is determined by the cooling water temperature.

The ECU 14 outputs a valve opening command for the fuel injection valve 124 and an ignition command for the spark plug 111 via the output interface 145. The ignition command output from the ECU 14 is boosted by the ignition coil 113 and distributed by the distributor 112 to the spark plug 111 of the cylinder 11. FIG. 2 is a flowchart of the first fuel injection amount calculation routine. In step 21, the internal combustion engine speed Ne, the throttle valve opening θ and the cooling water temperature THW are read.

In step 22, the internal combustion engine speed N
The basic fuel injection amount Q _BASE is calculated as a function of e and the throttle valve opening θ. As the Q _BASE = Q _BASE (Ne, θ) function, for example, the following multiplication can be applied. Q _BASE = K × Ne × θ where K is a constant.

In step 23, the cooling water temperature THW
However, it is determined whether or not the temperature is _{equal to} or higher than a predetermined threshold temperature T _TH at which it is determined that the internal combustion engine is in the high temperature operation state. Step 2
If an affirmative decision is made in step 3, the routine proceeds to step 24, where the fuel depletion count KTHW is determined as a function of the cooling water temperature THW. KTHW = KTHW (THW) FIG. 3 is an example of a graph for determining the fuel depletion count KTHW, in which the horizontal axis represents the cooling water temperature THW and the vertical axis represents the fuel depletion count KTHW. The fuel depletion count KTHW may be any reduction function of the cooling water temperature THW, and the function form is not particularly limited.

In step 25, when the internal combustion engine is in a high temperature operating state, the minimum fuel injection amount Q _HOT at high temperature that can keep the internal combustion engine rotating and suppress further overheating of the internal combustion engine is the internal combustion engine rotation speed. It is determined based on the number Ne. In step 26, the maximum fuel injection amount Q _MAX allowed at the current rotational speed when the internal combustion engine is not in the high temperature operation state is determined based on the internal combustion engine rotational speed Ne.

In step 27, the maximum fuel injection amount Q
_The updated fuel injection amount Q _NEW is calculated based on the following formula from _MAX , the minimum fuel injection amount Q _HOT at high temperature, and the fuel depletion count KTHW. Q _NEW = {Q _MAX −Q _HOT } × KTHW + Q _HOT Next, at step 27, the smaller one of the basic fuel injection amount Q _BASE and the updated fuel injection amount Q _NEW is the current fuel injection amount Q _EX.
To be determined.

Q _EX = MIN {Q _BASE , Q _NEW } Then, in step 28, the valve opening time for the fuel injection valve 124 is output via the output interface 145. When a negative determination is made in step 23, the process directly proceeds to step 29. FIG. 4 is a flow chart of the second fuel injection amount calculation routine, and steps 41 to 45 are the same as the first fuel injection amount calculation routine.

In step 46, the fuel injection amount Q _EX at the time of the previous fuel injection, the minimum fuel injection amount Q at high temperature
_The updated fuel injection amount Q _NEW is calculated from the _HOT and the fuel depletion count KTHW based on the following equation. Q _NEW = {Q _EX −Q _HOT } × KTHW + Q _HOT Next, the routine proceeds to step 47, where the smaller of the basic fuel injection amount Q _BASE and the updated fuel injection amount Q _NEW is the current fuel injection amount Q _EX.
To be determined.

Q _EX = MIN {Q _BASE , Q _NEW } Then, at step 48, the output time is output as the valve opening time for the fuel injection valve 124 via the output interface 145. When the negative determination is made in step 43, the process directly proceeds to step 48.

[0020]

According to the fuel injection control device of the present invention, the execution fuel injection amount is reduced in accordance with the ambient temperature of the internal combustion engine, so that the fuel injection amount is prevented from being suddenly decreased. Deterioration is suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a flowchart of a first fuel injection amount calculation routine.

FIG. 3 is a graph for determining a fuel reduction coefficient.

FIG. 4 is a flowchart of a second fuel injection amount calculation routine.

[Explanation of symbols]

 11 ... Cylinder 111 ... Spark plug 112 ... Distributor 113 ... Igniter 114 ... Cooling water temperature sensor 121 ... Air cleaner 122 ... Intake pipe 123 ... Intake valve 124 ... Fuel injection valve 125 ... Throttle valve 126 ... Throttle sensor 131 ... Exhaust pipe 132 ... Purification Device 14 ... ECU 141 ... Bus 142 ... CPU 143 ... Memory 144 ... Input interface 145 ... Output interface

Claims (1)

[Claims] 1. A detecting means for detecting an operating state of an internal combustion engine; a basic fuel injection amount calculating means for calculating a basic fuel injection amount based on the operating state of the internal combustion engine detected by the detecting means; Atmosphere temperature detecting means for detecting the ambient temperature, and when the ambient temperature of the internal combustion engine detected by the ambient temperature detecting means is equal to or higher than a predetermined temperature, while preventing over-rotation or overheating of the internal combustion engine High temperature minimum fuel injection amount calculation means for calculating the minimum temperature high temperature fuel injection amount necessary to maintain rotation of the internal combustion engine, current fuel injection amount, high temperature calculated by the high temperature minimum fuel injection amount calculation means Time minimum fuel injection amount, and an updated fuel injection amount calculation means for calculating an updated fuel injection amount based on the ambient temperature of the internal combustion engine detected by the ambient temperature detection means. An execution fuel injection amount calculation means for calculating the smaller one of the basic fuel injection quantity calculated by the basic fuel injection quantity calculation means and the update fuel injection quantity calculated by the update fuel injection quantity calculation means as the execution fuel injection quantity; , A fuel injection control device comprising: