JPH0742604A - Fuel injection timing control device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to perform fuel injection at an optimum timing according to the operating state of the engine, and to eliminate the possibility of causing large fluctuations in the air-fuel ratio due to fluctuations in the injection timing. [Structure] The engine 1 receives fuel injected from an injector 4 provided for each cylinder. The distributor 11 is provided with a crank angle sensor 27 for detecting a change in the crank angle of the engine 1 at a rate of 30 ° CA according to the rotation of the rotor. An ECU (electronic control unit) 30 drives and controls the injector 4 based on detection signals from various sensors 21 to 27. The ECU 30 executes fuel injection between the crank counters that are counted for each unit angle with a delay from the calculated immediately preceding timing counter by a deviation time. Then, more precise fuel injection is performed, and even if the fuel injection time or the like changes, the intake time of the evaporated fuel in the intake process does not significantly change.
Also, the injection timing is not set at an extremely early stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device for an internal combustion engine, and more particularly to a fuel injection timing control device for adjusting the fuel injection timing of a gasoline engine by electronic control.

[0002]

2. Description of the Related Art Conventionally, as this type of technology, for example, the one disclosed in Japanese Patent Application Laid-Open No. 2-23251 is known. In this technique, the intake air amount of the engine, that is, the load is detected at a predetermined timing. Then, the fuel injection amount is calculated according to the load, and the fuel injection is performed for each cylinder at a predetermined timing. Further, the fuel injection timing is changed according to the load, that is, depending on whether the engine load at that time is high or low.

Here, as a change pattern of the fuel injection timing, a pattern corresponding to a pulse (timing) detection signal from the crank angle sensor is adopted. That is, when the fuel injection timing is changed, for example, 180 ° CA
The fuel injection is executed by shifting the timing detection signal such as every one or every 90 ° CA by one.

[0004]

However, in the above-mentioned prior art, the injection timing is changed only every 180 ° CA, every 90 ° CA, or the like according to the timing detection signal from the crank angle sensor. I can't.

Therefore, the detected angle per minute (for example, 180
In some cases, the injection timing was deviated. As a result, in some cases, the time during which the fuel evaporates and is inhaled may significantly change in the intake stroke. When the degree of evaporation changes greatly in this way, the air-fuel ratio that contributes to combustion may also change greatly.

On the other hand, various techniques for precisely controlling the injection timing have been proposed. That is, at the intake top dead center of the previous cycle, the timing for the next injection is reserved in advance, and the timing is set in the timer. However, in such a case, the injection timing was reserved too early. Therefore, in a transient state where the fuel injection amount changes, the actual injection timing may deviate from the optimum injection timing. Also,
In this technique, since the injection timing is reserved early, even if there is a request for asynchronous injection, the control may not be executed after the reservation.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to be able to execute fuel injection at an optimum timing according to the operating state of an internal combustion engine, and to prevent fluctuations in the injection timing. Accordingly, it is an object of the present invention to provide a fuel injection timing control device for an internal combustion engine that does not cause a large change in the air-fuel ratio.

[0008]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, a crankshaft M2 rotatably provided in an internal combustion engine M1 and a crankshaft M2 are rotated. Along with this, a timing signal generating means M3 that generates a timing signal for each predetermined unit angle, a counting means M4 that is cleared every two revolutions of the crankshaft M2 and counts the position of the timing signal, and an internal combustion engine M1.
Fuel injection means M5 for injecting fuel into the internal combustion engine M1 in order to perform combustion at the same time, and when the injection execution timing comes, the fuel injection means M5 is controlled. Fuel injection control means M6 for injecting fuel into the internal combustion engine M1, operating state detecting means M7 for detecting the operating state of the internal combustion engine M1, and operating state detecting means M7.
Fuel injection time calculation means M8 for calculating the fuel injection time based on the operating state detected by the fuel injection control means M8
5, the injection timing calculation means M9 for calculating the position of the timing signal immediately before the next injection start timing based on the fuel injection time calculated by the fuel injection time calculation means M8 and the injection end timing. Based on the fuel injection time calculated by the injection time calculation means M8 and the injection end timing, the deviation time between the timing signal generation timing calculated by the injection timing calculation means M9 and the actual fuel injection timing is calculated. A deviation time calculating means M10 and a timer means M11 for setting the deviation time calculated by the deviation time calculating means M10 when the timing signal is generated and for determining that the injection timing has come after the deviation time elapses. The point is to have

[0009]

According to the above structure, as shown in FIG. 1, the timing signal generating means M3 causes the timing signal to be generated at predetermined unit angles in accordance with the rotation of the crankshaft M2 rotatably provided in the internal combustion engine M1. Occurs. Further, the position of the timing signal is counted by the counting means M4, and the count is cleared every two revolutions of the crankshaft M2. The fuel is injected into the internal combustion engine M1 by the fuel injection means M5, the fuel injection amount is adjusted, and as a result, the combustion in the internal combustion engine M1 is executed. Further, when the injection execution timing arrives, the fuel injection control means M6 controls the fuel injection means M5 to inject fuel into the internal combustion engine M1.

The internal combustion engine M1 is operated by the operating state detecting means M7.
Is detected, and the fuel injection time calculation means M8 calculates the fuel injection time based on the operation state.
When the fuel injection control means M5 executes the injection,
Based on the fuel injection time calculated by the fuel injection time calculation means M8 and the injection end timing, the injection timing calculation means M9 calculates the position of the timing signal immediately before the next injection start timing. Further, on the basis of the fuel injection time calculated by the fuel injection time calculation means M8 and the injection end timing, the deviation time calculation means M10 calculates the timing signal generation timing calculated by the injection timing calculation means M9 and the actual timing. The deviation time from the fuel injection timing of is calculated. Furthermore, in the timer means M11, when the timing signal is generated, the deviation time calculating means M
The deviation time calculated by 10 is set, and it is assumed that the injection timing has arrived after the deviation time has elapsed. Then, the fuel injection means M5 is controlled and the fuel is injected into the internal combustion engine M1.

Therefore, even between the timing signals generated at every predetermined unit angle, fuel injection delayed by the above-mentioned deviation time becomes possible, and more precise fuel injection can be executed. Therefore, even if the injection timing changes, the intake time of the vaporized fuel in the intake process does not change significantly.

Further, the shift time is set when the timing signal is generated, and is not set extremely early. Therefore, even in a transient state where the fuel injection amount changes, the actual injection timing becomes close to the optimum injection timing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a fuel injection timing control system for an internal combustion engine according to the present invention is embodied in a gasoline engine will be described below in detail with reference to the drawings.

FIG. 2 is a schematic diagram showing the engine system in this embodiment. Outside air is taken from an air cleaner 3 through an intake passage 2 into an engine 1 as an internal combustion engine having a plurality of cylinders (six cylinders in this embodiment). Simultaneously with the intake of the outside air, the fuel injected from the injector 4 as the fuel injection means provided for each cylinder in the vicinity of the intake port 1a is taken into the engine 1. Then, the mixture of the taken fuel and the outside air is introduced into the combustion chamber 1b through the intake valve 5a provided for each cylinder. The air-fuel mixture is exploded / combusted in the combustion chamber 1b, a crankshaft (not shown) is rotated, and a driving force is obtained for the vehicle. Then an explosion
The exhaust gas after combustion is led out to the exhaust passage 6 where the exhaust manifold for each cylinder gathers via the exhaust valve 5b,
It is discharged to the outside.

A throttle valve 8 which is opened and closed in conjunction with an accelerator pedal (not shown) is provided in the intake passage 2. And this throttle valve 8
The amount of intake air to the intake passage 2 is adjusted by opening and closing. A surge tank 9 for smoothing the pulsation of intake air is provided downstream of the throttle valve 8.

An intake air temperature sensor 21 for detecting the intake air temperature is provided near the air cleaner 3 in the intake passage 2. A throttle sensor 22 for detecting the opening of the throttle valve 8, that is, the throttle opening TA is provided near the throttle valve 8. In addition, surge tank 9
Is communicated with the tank 9 and suction pressure (intake pressure) PiM
Intake pressure sensor 23 as a shift state detecting means for detecting the
Is provided.

On the other hand, an oxygen sensor 24 for detecting the oxygen concentration OX in the exhaust gas is provided in the exhaust passage 6. Further, the engine 1 is provided with a water temperature sensor 25 for detecting the temperature (cooling water temperature) THW of the cooling water, and the distributor 11 distributes the spark plug 10 provided for each cylinder of the engine 1. The ignition signal is applied. Distributor 11 is igniter 12
It is for distributing the high voltage output from the ignition plugs 10 in synchronization with the crank angle of the engine 1. The ignition timing of each ignition plug 10 is determined by the high voltage output timing from the igniter 12.

The distributor 11 is provided with a rotation speed sensor 26 for detecting the rotation speed (engine speed) NE of the engine 1 from the rotation of a rotor (not shown) of the distributor 11. Similarly, the distributor 11 is provided with a crank angle sensor 27 which constitutes a timing signal generating means and a counting means for detecting a change in the crank angle of the engine 1 at a predetermined rate according to the rotation of the rotor. In this embodiment, 1
Assuming that the engine 1 makes two revolutions with respect to the stroke, the crank angle sensor 27 detects the crank angle at a rate of "30 ° CA". Then, the intake air temperature sensor 21, the throttle sensor 22, the intake pressure sensor 23,
Oxygen sensor 24, water temperature sensor 25, rotation speed sensor 26,
The crank angle sensor 27 or the like constitutes an operating state detecting means.

In this embodiment, the electronic control unit (hereinafter simply referred to as "ECU") 30 constitutes fuel injection control means, fuel injection time calculation means, injection timing calculation means, deviation time calculation means and timer means. ing. An intake air temperature sensor 21, a throttle sensor 22, an intake pressure sensor 23, an oxygen sensor 24, a water temperature sensor 25, a rotation speed sensor 26, and a crank angle sensor 27 are connected to the ECU 30, respectively. Further, the injector 4 and the igniter 12 are connected to the ECU 30, respectively. Then, the ECU 30 uses the sensors 2
The injector 4 and the igniter 12 are drive-controlled based on the detection signals from 1-27.

Next, the structure of the ECU 30 will be described with reference to the block diagram of FIG. The ECU 30 includes a central processing unit (CPU) 31, a read-only memory (ROM) 32 that stores a predetermined control program and the like in advance, and a random access memory (RA) that temporarily stores calculation results of the CPU 31 and the like.
M) 33, a backup RAM 34 for storing previously stored data, and the like. Then, the ECU 30
These units are connected to an external input circuit 35, an external output circuit 36, etc. by a bus 37 to constitute a logical operation circuit.

The external input circuit 35 includes an intake air temperature sensor 21, a throttle sensor 22, an intake pressure sensor 23,
An oxygen sensor 24, a water temperature sensor 25, a rotation speed sensor 26, a crank angle sensor 27, etc. are connected to each other.
The injector 4 and the igniter 12 described above are connected to the external output circuit 36, respectively.

Then, the CPU 31 reads the detection signals from the sensors 21 to 27 as input values via the external input circuit 35. In addition, the CPU 31 is based on these input values,
The injector 4, the igniter 12, and the like are preferably controlled via the external output circuit 36.

Next, of the various processing operations executed by the ECU 30 described above, the processing operations for controlling the fuel injection timing will be described with reference to FIGS. The flowchart shown in FIG. 4 is a “main routine” executed by the ECU 30 for calculating the fuel injection time TAU and the like, which is started at the same time as the cranking of the engine 1 is completed, and thereafter is a regular interrupt at predetermined time intervals. To be executed.

When the processing of this routine is started, first, at step 101, the fuel injection time TAU corresponding to the fuel injection amount is calculated. Where fuel injection time TAU
Is calculated according to the following equation (1).

TAU = GNFWD * FEFI + FMW (1) where GNFWD is the prefetch load amount, and the intake pressure PiM
And the intake air intake amount calculated based on the engine speed NE are separately set. FEFI is a comprehensive correction coefficient, and is a collection of various correction amounts such as a warm-up amount increase coefficient and an air-fuel ratio feedback correction coefficient. Further, FMW is a wetting amount of the manifold, and more specifically, it is a correction amount of the fuel adhering to the wall surface of the intake manifold.

Next, at step 102, the injection start angle THINJ converted from the top dead center is calculated. Here, the injection start angle THINJ is calculated according to the following equation (2).

THINJ = (TAU + TAUV + TB) * 10 ⁻⁶ * 360 (° CA) * NE / 60 (sec) + X (° CA) (2) where TAUV is an invalid injection time and the injector 4
Is added to compensate for the operation delay. Further, TB is a spray flight time, which is substantially determined by the distance from the injector 4 to the intake valve 5a. Furthermore, X is the injection arrival (end) timing converted from the top dead center.

Then, the subsequent processing is temporarily terminated. As described above, in the main routine, the fuel injection time TAU is calculated and the injection start angle THINJ is calculated.
Is calculated.

Next, a routine for calculating the deviation time CPRINJT will be described. The flowchart shown in FIG. 5 is a "deviation time calculation routine" executed by the ECU 30, and is executed by a regular interruption every predetermined time (for example, "30 ms").

When the processing shifts to this routine, first, at step 201, the crank counter CCRNK is
, It is determined whether or not it matches the immediately preceding timing counter CCRINJEX previously calculated in the previous routine. Here, the crank counter CCRNK corresponds to the crank angle detected by the crank angle sensor 27 at a rate of "30 ° CA" and sequentially takes a value from "0" to "23". Then, the crank counter CCRNK becomes "2.
After reaching "3", it is assumed that the crankshaft has made one revolution and is cleared to "0" next time. Further, the immediately preceding timing counter CCRINJEX sets the injection start angle THINJ calculated in the "main routine" to "30 ° C.
The "quotient" divided by "A" is associated with each cylinder.

If the crank counter CCRNK does not match the immediately preceding timing counter CCRINJEX, the subsequent processing is temporarily terminated. On the other hand, the crank counter CCRNK indicates the immediately preceding timing counter CCRI.
If it coincides with NJEX, the process proceeds to step 202 to execute the injection execution process.

In step 202, the deviation time CP
RINJTX is calculated and the value is set in a predetermined timer. Here, the deviation time CPRINJTX
Is equivalent to the “remainder” when the injection start angle THINJ calculated in the “main routine” is divided by “30 ° CA”. That is, the remaining time from the immediately preceding timing counter CCRINJEX to the injection start is set in the timer dedicated to the injection start timing control.

Then, in the following step 203,
To prepare for the next routine, the immediately preceding timing counter CCRINJEX is calculated and set.
The method of calculating the immediately preceding timing counter CCRINJEX has been described in step 201, so the description thereof will be omitted here. Then, the subsequent processing is temporarily terminated.

As described above, in this "deviation time calculation routine", the immediately preceding timing counter CCRINJE in which the crank counter CCRNK is calculated and set in advance.
When it matches with X, the shift time CPRINJTX is calculated and set in the timer.

Next, a routine for actually executing the injection will be described. The flowchart shown in FIG. 6 is EC
It is a "timer interrupt routine" executed by U30, and has a predetermined injection timing (for example, "120 ° C").
A "). More specifically, the "deviation time calculation routine" is executed each time the deviation time CPRINTX set in a predetermined timer elapses.

When the processing shifts to this routine, first, at step 301, a fuel injection subroutine is executed so as to execute the injection for the corresponding cylinder. That is, the timer comparison process corresponding to the cylinder to be injected is performed, and the immediate start and end of the injection are reserved.
Here, in this embodiment, the processes of the synchronous injection for each cylinder and the asynchronous injection for all cylinders are common, and the cylinder number and the fuel injection time TAU may be input. Since one compare timer is prepared for each cylinder, reservations for immediate start and end of injection are made exclusively for each cylinder.

Then, in step 302, the cylinder number is updated to the next one. That is, the number of the cylinder to be injected next time is reserved. Then, the subsequent processing is temporarily terminated. Thus, in this "timer interrupt routine", the actual injection is executed and the number of the cylinder to be injected next is reserved.

The above flow will be described in more detail by taking one cylinder (cylinder # 4) as an example. That is, as shown in FIGS. 7 and 8, based on the calculated fuel injection time TAU, etc.,
The injection start angle THINJ is calculated from the injection end timing (here, the injection end timing is the top dead center for convenience, that is, X = “0”) (step 102). Based on this calculation, the immediately preceding timing counter CCRINJEX
Is determined (CCRINJEX = “21” in the figure).
Then, when the crank counter CCRNK coincides with the immediately preceding timing counter CCRINJEX, the deviation time CPRINJTX (right-angled triangle portion in the figure) is calculated,
It is set in the timer (step 201, step 202). Also, the immediately preceding timing counter CCRINJEX (for the next cylinder # 5) is set. Then, injection is executed after the lag time CPRINTX has elapsed (step 301), and the cylinder number is updated to the next number (# 5) (step 302).

As described above, in this embodiment, even between the crank counters CCRNK which are counted for each predetermined unit angle (“30 ° CA”), the time difference CPRINJTX from the immediately preceding timing counter CCRINJEX is calculated. The fuel injection can be delayed by just that, and more precise fuel injection can be executed. for that reason,
Even if the fuel injection time TAU or the like fluctuates and the injection timing fluctuates, the intake time of the evaporated fuel in the intake stroke does not change significantly. As a result, engine 1
It is possible to execute the fuel injection at an optimum timing according to the operating state of, and it is possible to eliminate the possibility that the air-fuel ratio will greatly fluctuate with the fluctuation of the injection timing.

The deviation time CPRINJTX is
It is set when the crank counter CCRNK and the immediately preceding timing counter CCRINJEX match,
It is not set at an extremely early stage. for that reason,
Even in a transient state where the fuel injection amount changes, the actual injection timing can be close to the optimum injection timing.

Further, in this embodiment, the start of injection is
Since one compare timer is prepared for each cylinder, reservations for immediate start and end of injection are made exclusively for each cylinder. Therefore, even if there is a request for asynchronous injection, it is possible to meet such a request at least until the deviation time CPRINJTX is set.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the embodiment, the gasoline engine 1 having 6 cylinders is embodied, but the number of cylinders is not particularly limited,
It may also be embodied in a diesel engine.

(2) In the above embodiment, the crank counter CCRNK uses the crank angle sensor 27 of "30".
The crank angle is detected at a rate of "0 CA", and the values are sequentially set to "0" to "23", but the crank angle may be detected at a finer rate.

[0044]

As described in detail above, according to the fuel injection timing control system for an internal combustion engine of the present invention, the fuel injection can be executed at the optimum timing according to the operating state of the internal combustion engine, and the injection timing It is possible to eliminate the possibility of causing a large change in the air-fuel ratio due to the change in the fuel injection amount, and it is possible to make the actual injection timing close to the optimum injection timing even in a transient state where the fuel injection amount changes. It has an excellent effect that it can be done.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel injection timing control device for an internal combustion engine in an embodiment embodying the present invention.

FIG. 3 is a block diagram showing an electrical configuration of an ECU and the like in one embodiment.

FIG. 4 is a flowchart showing a “main routine” executed by the ECU in the embodiment.

FIG. 5 is a flowchart showing a “deviation time calculation routine” executed by the ECU in the embodiment.

FIG. 6 is a flowchart showing a “timer interrupt routine” executed by the ECU in the embodiment.

FIG. 7 is a timing chart for explaining a flow of timing control processing at the time of fuel injection in a predetermined cylinder in one embodiment.

FIG. 8 is a timing chart for explaining a flow of a timing control process at the time of fuel injection between cylinders in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 4 ... Injector as fuel injection means, 21 ... Intake temperature sensor constituting operating state detecting means, 22 ... Throttle sensor constituting operating state detecting means, 23 ... Operating state detecting means Intake pressure sensor, 24 ... Oxygen sensor forming operating state detecting means, 25 ... Water temperature sensor forming operating state detecting means, 2
6 ... Rotational speed sensor constituting operating state detecting means, 27 ...
A crank angle sensor constituting the timing signal generating means, the counting means and the operating state detecting means, 30 ... EC constituting the fuel injection control means, the fuel injection time calculating means, the injection timing calculating means, the deviation time calculating means and the timer means.
U.

Claims (1)

[Claims] 1. A crankshaft rotatably provided in an internal combustion engine, timing signal generating means for generating a timing signal for each predetermined unit angle in accordance with the rotation of the crankshaft, and for every two revolutions of the crankshaft. Counting means for clearing and counting the position of the timing signal; fuel injection means for injecting fuel into the internal combustion engine and adjusting the fuel injection amount while executing combustion in the internal combustion engine; Fuel injection control means for controlling the fuel injection means to inject fuel into the internal combustion engine when the timing of execution comes, operating state detection means for detecting an operating state of the internal combustion engine, and the operating state detection means Fuel injection time calculation means for calculating the fuel injection time based on the operating state detected by the fuel injection control means, Injection timing calculation means for calculating the position of the timing signal immediately before the next injection start timing based on the fuel injection time calculated by the fuel injection time calculation means and the injection end timing, and calculated by the fuel injection time calculation means. The fuel injection time and the injection end timing, the deviation time calculating means for calculating the deviation time between the generation timing of the timing signal calculated by the injection timing calculating means and the actual fuel injection timing, and the timing. An internal combustion engine, comprising: when the signal is generated, setting the deviation time calculated by the deviation time calculating means, and timer means for assuming that the injection timing has come after the deviation time has elapsed. Fuel injection timing control device.