JPH06146982A - Fuel injection controller for in-cylinder direct injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an in-cylinder internal combustion temperature so as to be lower than a specific threshold temperature and enable correction of disper sion among cylinders. CONSTITUTION:Combustion temperature sensors 105a, 105d are provided on swirl chambers 103a, 103d of cylinders 101a, 101d of an internal combustion engine 10, and each measured temperature is input in a controller 13. Amount of fuel injection in relation to each cylinder is determind by correcting dispersion among cylinders in consideration of a reference amount of fuel injeciton, which is determined based on the measured values of a rotation speed sensor 123 and an axle opening sensor 141. A coefficient of re-correction is determined according to a deviation from an average value of combustion temperature of each cylinder, and the amount of fuel injeciton is re-corrected so that deviation among cylinders is reduced in a range that does not exceed a fixed maximum temperature. A coefficient of correction is learned based on the re- correcction value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a direct injection type internal combustion engine, which injects fuel directly into a cylinder, and more particularly, when the combustion temperature in the cylinder rises excessively and the internal combustion engine is damaged. The present invention relates to a fuel injection control device for a cylinder direct injection internal combustion engine capable of preventing the above.

[0002]

2. Description of the Related Art A so-called distributed fuel injection pump is generally used in a direct injection type internal combustion engine, such as a diesel engine, which directly injects fuel into a cylinder. The fuel injection start timing is controlled by the opening rate of the timer control valve, and the fuel injection end timing is controlled by the spill valve opening timing.

That is, the fuel injection start timing and the fuel injection amount are determined as a function of the internal combustion engine speed and the accelerator opening degree, and after the time required to inject a predetermined fuel injection amount into each cylinder after the start of the fuel injection, the spill valve is started. Is opened to stop fuel injection. However, the distributed fuel injection pump is composed of a large number of parts such as a spill ring, a plunger, and a spring, and the amount of fuel actually supplied to the cylinders varies due to variations in the manufacturing of these parts or changes in characteristics over time. It may fluctuate.

In particular, when the fuel is supplied in an amount larger than a predetermined amount, the combustion temperature in the combustion chamber excessively rises, which may damage the internal combustion engine. To solve this problem,
It has been proposed to install a combustion temperature sensor for detecting the temperature of the combustion chamber and correct the opening timing of the spill valve so that the temperature of the combustion chamber does not exceed a predetermined threshold value (Japanese Patent Laid-Open No. Sho 5).
8-172436).

[0005]

However, in reality, even if the combustion chamber temperature is controlled to be equal to or lower than a predetermined threshold temperature, it is necessary to avoid the occurrence of variations in the amount of fuel supplied between the cylinders. I can't. That is, variations in the combustion state between cylinders occur due to variations in the spring constant of the fuel injection pump, differences in the compression ratio due to tolerances in the fuel injection valve itself, variations in the structure of the combustion chamber, etc. There is a possibility that a variation of about C occurs and damage occurs.

The present invention has been made in view of the above problems, and it is an in-cylinder direct injection type that makes it possible to make the in-cylinder combustion temperature below a predetermined threshold temperature and to correct the variation between the cylinders. An object of the present invention is to provide a fuel injection control device for an internal combustion engine.

[0007]

A fuel injection control apparatus for a direct injection type internal combustion engine, which directly injects a reference fuel injection amount determined based on an operating state of the internal combustion engine into each cylinder of the internal combustion engine, according to the present invention. In this case, at least one is attached to two adjacent cylinders of the internal combustion engine, and at least two are attached to all the cylinders of the internal combustion engine. , Cylinder internal temperature measured by the temperature detector to reduce the variation of each cylinder internal temperature, and to prevent each cylinder internal temperature from exceeding a predetermined threshold temperature A reference fuel injection amount correction means for correcting the reference fuel injection amount,
It is equipped with.

[0008]

The cylinder internal temperature is measured for each cylinder, and the fuel injection amount is corrected for each cylinder so as to prevent the internal temperature of each cylinder from being less varied and exceeding a preset threshold value. .

[0009]

1 is a block diagram of an embodiment of a fuel injection control device for a direct injection type internal combustion engine according to the present invention, in which a diesel internal combustion engine 10 has four cylinders 101a to 101d.
(Only two cylinders 101a and 101d are shown in FIG. 1). The diesel engine 10 is a so-called swirl type, and corresponds to the cylinders 101a and 101d, in addition to the main combustion chambers 102a and 102b, swirl chambers 103a and 103a.
03d is installed.

Further, in the swirl chambers 103a and 103d, a fuel injection valve 104a for injecting fuel into the cylinder.
And 104d, and combustion temperature sensors 105a and 105d for measuring the combustion temperature in the cylinder. Fuel is supplied to the fuel injection valves 104a and 104d from a well-known distributed fuel injection pump 12 via fuel supply pipes 11a and 11b. The amount of fuel supplied from the distributed fuel injection pump 12 is determined by the timer control valve 1
It is adjusted by the valve opening ratio of 21 and the operation timing of the spill control solenoid 122.

The diesel internal combustion engine having the above structure is controlled by the control device 13 which is composed of, for example, a microcomputer. The control device 13 takes in the combustion temperatures measured by the combustion temperature sensors 105a and 105d. Command signals are output to the timer control valve 121 and the spill control solenoid 122. In addition, as the operating state of the diesel internal combustion engine, the rotation speed measured by the rotation speed sensor 123 incorporated in the distribution type fuel injection pump 12 and the depression amount of the accelerator pedal 141 detected by the accelerator sensor 141 are input.

Unless otherwise noted, the following processing is performed for the cylinder currently controlled by the four cylinders 101a to 101d (referred to as a controlled cylinder).
For variables that exist for each cylinder, the subscript a that indicates the cylinder
Omit d. 2 is executed in the control device 13,
7 is a flowchart of a timer control valve control routine for a control target cylinder, which is interrupted at every predetermined rotation angle.

In step 21, the rotational speed Ne and the accelerator pedal depression amount Accp are read. In step 22, the timer control valve opening timing TCV is determined as a function of the rotation speed Ne and the accelerator pedal depression amount Accp, and in step 23, the timer control valve opening timing TCV is output to open the timer control valve.

By this processing, fuel supply to the cylinder to be controlled is started at a predetermined cam angle. FIG. 3 is a flowchart of a spill control routine executed in the control device 13, and similarly, interrupt processing is performed at every predetermined rotation angle. In step 31, the rotation speed Ne and the accelerator pedal depression amount Accp are read, and in step 32, the reference spill control solenoid excitation timing TAUBASE is determined as a function of the rotation speed Ne and the accelerator pedal depression amount Accp.

In step 33, the reference spill control solenoid excitation timing TAUBASE is multiplied by the correction coefficient K to obtain the corrected spill control solenoid excitation timing TAUCMP. Step 34
And 35, it is determined whether or not the diesel internal combustion engine is in a steady operation state. That is, in step 34, the cooling water temperature Tw
Is above a predetermined threshold temperature, for example 80 ° C. or higher, and in step 35 it is determined whether the rotational speed Ne is substantially constant.

When both the step 34 and the step 35 are affirmatively determined, the process proceeds to step 36, the correction spill control solenoid excitation timing is corrected again, and the step 37 is performed.
Proceed to. If a negative determination is made in either step 34 or 35, the process directly goes to step 37. In step 37, the corrected spill control solenoid excitation timing TAUCMP is output to drive the spill control solenoid 122 to spill the fuel and stop the fuel injection.

In step 38, it is determined whether or not the correction coefficient K needs to be learned. When the determination is affirmative, the correction coefficient K is learned in step 39, and this routine is ended. On the contrary, if a negative determination is made in step 38, this routine is directly ended. As a result, the spill valve corresponding to the control target cylinder opens at a predetermined timing, and the fuel supply to the control target cylinder is stopped.

FIG. 4 shows step 3 of the spill control routine.
6 is a flowchart of a correction spill control solenoid excitation timing recorrection process executed in 6. In-cylinder combustion temperature θ measured by the combustion temperature sensors 105a to 105d in step 361
Read a to θd. In step 362, the average value θav of the combustion temperatures θa to θd in the four cylinders is calculated.
At 3, the deviation Δθ from the average value θav (representing the deviation of the cylinder to be controlled) is calculated.

That is, the processes of steps 361 to 363 are executed for the combustion temperatures of the four cylinders. Step 3
At 64, the recorrection coefficient α for the corrected spill control solenoid excitation timing TAUCMP is calculated as a function of the deviation Δθ. FIG. 5 is a graph for determining the correction coefficient α, where the horizontal axis represents the deviation Δθ and the vertical axis represents the correction coefficient α.

In step 365, it is determined whether or not the in-cylinder temperature θ is equal to or lower than a predetermined maximum temperature θmax. If a negative determination is made, the process proceeds to step 366, and step 36
It is determined whether the recorrection coefficient α obtained in 4 is larger than 1.0. If an affirmative decision is made in step 366, the operation proceeds to step 367, in which the recorrection coefficient α is set to a numerical value of 1.0 or less,
For example, the value is replaced with 1.0 and the process proceeds to step 368. In addition, when an affirmative determination is made in step 365 and step 3
Also when the negative determination is made in 66, the process proceeds to step 368.

The processing from step 365 to step 367 is carried out by determining the maximum combustion temperature .theta.
This is a process for preventing the current fuel injection amount from increasing and the in-cylinder combustion temperature to rise when it is equal to or greater than max. In step 368, the corrected spill control solenoid excitation timing TAUCMP is multiplied by the correction coefficient α to recorrect the corrected spill control solenoid excitation timing TAUCMP, and this routine ends.

FIG. 6 shows step 39 of the spill control routine.
6 is a flowchart of the correction coefficient learning process executed in step S6, which is executed for each cylinder. In step 391, the ratio Knew between the re-corrected spill control solenoid excitation timing TAUCMP and the reference spill control solenoid excitation timing TAUBASE is calculated, and in step 392 the ratio Knew is set to a predetermined minimum value Kmi.
It is determined whether it is between n and the maximum value Kmax.

If an affirmative decision is made in step 392, the operation proceeds to step 393, in which it is checked whether the ratio of the correction coefficient K used so far to the correction coefficient Knew calculated this time is equal to or less than a predetermined threshold value ΔK. If the judgment is affirmative, the routine proceeds to step 394, where the value of the correction coefficient K is rewritten to the correction coefficient Knew calculated this time, and this routine is ended. When a negative determination is made in step 392 or step 393, it is determined that the correction amount is too large, or the amount of change from the correction coefficient used before is too large, and step 3
At 95, an alarm is issued and this routine is ended.

Although the internal combustion engine with a swirl chamber has been described above, it can be applied to a so-called direct injection type internal combustion engine. Further, in a four-cylinder internal combustion engine, a first temperature detector representing the in-cylinder temperature of the two cylinders is provided between the first cylinder and the second cylinder, and a second temperature detector is provided between the third cylinder and the fourth cylinder. A second temperature detector that represents the in-cylinder temperature of one cylinder may be provided and controlled by the two temperature detectors.

[0025]

As described above, according to the present invention, by measuring the combustion temperature for each cylinder, it is possible to control the combustion temperature of each cylinder so as not to exceed a predetermined maximum temperature. Not only is it possible, but it is also possible to control so that the variation in combustion temperature between the cylinders is reduced at the same time, so it is possible to more reliably prevent excessive thermal stress from occurring in the cylinders.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a flowchart of a timer control valve control routine.

FIG. 3 is a flowchart of a spill control routine.

FIG. 4 is a flowchart of a correction spill control solenoid excitation timing recorrection process.

FIG. 5 is a graph for determining a recorrection coefficient.

FIG. 6 is a flowchart of a correction coefficient learning process.

[Explanation of symbols]

 10 ... Diesel internal combustion engine 101a, d ... Cylinder 102a, d ... Main combustion chamber 103a, d ... Vortex chamber 104a, d ... Fuel injection valve 105a, d ... Combustion temperature sensor 11a, d ... Fuel supply pipe 12 ... Fuel injection pump 121 ... Timer control valve 122 ... Spill control solenoid 123 ... Rotation speed sensor 13 ... Control device 141 ... Accelerator opening sensor 142 ... Accelerator pedal

Claims (1)

[Claims] 1. A fuel injection control device for a direct injection type internal combustion engine, wherein a reference fuel injection amount determined based on an operating state of the internal combustion engine is directly injected into each cylinder of the internal combustion engine. A temperature detector for measuring the temperature inside the cylinder of the internal combustion engine, wherein at least one is installed for two adjacent cylinders and at least two is installed for all the cylinders of the internal combustion engine; The reference fuel injection is performed for each cylinder so that the variation in the temperature in each cylinder is reduced and the temperature in each cylinder does not exceed a predetermined threshold temperature based on the determined cylinder temperature. A fuel injection control device for a direct injection type internal combustion engine, comprising: a reference fuel injection amount correction means for correcting the amount.