JP2001323831A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the startability of an internal combustion engine and surely prevent the exhaust of unburned gas in starting. SOLUTION: Fuel injection in starting of the internal combustion engine 30 is prohibited on the basis of the specified condition. Practically, as the specified condition, when at least one of a crank angle sensor 1, a cam angle sensor 6, and a B/URAM is abnormal, or when at least one of the cooling water temperature of the internal combustion engine 30, battery voltage, and fuel pressure is low, pre-injection is prohibited because the exhaust gas is increased or the startability of the internal combustion engine 30 is dropped. Thereby, the startability of the internal combustion engine is enhanced and the exhaust of the unburned gas is surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine applied to an internal combustion engine having a plurality of cylinders.

[0002]

2. Description of the Related Art Conventionally, as a prior art document related to a control device for an internal combustion engine, one disclosed in Japanese Patent Application Laid-Open No. 7-83093 is known. In this technique, a technique for suppressing the emission of unburned gas and improving the startability of an internal combustion engine is disclosed.

[0003]

However, in the above-described apparatus, the rotational position at the time of the previous stop of the rotation of the internal combustion engine cannot be accurately stored or the rotational position may be deviated at the start of the engine. In addition, if fuel is injected and supplied to a cylinder that should not be injected, there is a problem that the fuel cannot be ignited and unburned gas is discharged.

[0004] The reason for this will be described below. Normally, as a crank angle sensor or a cam angle sensor, a magnetic pickup or a magnetic resistance element (MRE) is used.
ent: magnetoresistive element) or the like, but these cannot detect the reverse rotation that occurs when the rotation of the internal combustion engine stops. That is, the rotational position immediately before the internal combustion engine stops rotating is
In the vicinity of the compression TDC (Top Dead Center) of a certain cylinder, the compressed air normally pushes back the cylinder, and the rotation is reversed. However, even when the reverse rotation occurs, the crank angle sensor and the cam angle sensor output a pulse, so that the microcomputer erroneously determines that the internal combustion engine has exceeded the compression TDC.

[0005] Further, in the case of a magnet pickup, when the rotation speed becomes low, the output becomes small, so that an output signal cannot be detected. Then, the microcomputer conversely detects the rotational position of the internal combustion engine further forward. Further, when the rotation speed of the internal combustion engine is low, for example, at the time of starting, the output signal from the magnet pickup cannot be detected in the same manner, so that it is erroneously determined that the rotational position has not advanced. Under such circumstances,
When (Pre-injection) is executed, the injected fuel cannot be ignited because the rotational position of the internal combustion engine has not been determined, and as a result, the injected fuel increases the wetness in the cylinder and discharges unburned gas. It leads to

Accordingly, the present invention has been made to solve such a problem, and has improved the startability of an internal combustion engine.
It is an object of the present invention to provide a control device for an internal combustion engine that can reliably prevent the emission of unburned gas at that time.

[0007]

According to the first aspect of the present invention, prior to the cylinder discrimination of an internal combustion engine having a plurality of cylinders, a crank angle sensor and a cam angle sensor correspond to the combustion cycle of each cylinder. Since the rotational position is not determined, the preceding injection (Pre-injection) is performed based on the rotational position of the internal combustion engine at the previous rotation stop stored in the position storage means.
n) Fuel injection at the time of starting by the control means is executed. Here, fuel injection at the time of starting the internal combustion engine is prohibited by the preceding injection prohibiting means based on predetermined conditions. In other words, the advance injection is prohibited when a predetermined condition that may cause inconvenience if the advance injection is performed at the time of starting is satisfied. Thus, the startability of the internal combustion engine is improved, and the discharge of unburned gas is appropriately prevented.

In the control apparatus for an internal combustion engine according to the present invention, when at least one of the crank angle sensor, the cam angle sensor, and the position storage means is abnormal in the preceding injection inhibiting means, for example, when the internal combustion engine is rotating. Precise injection is prohibited because the position accuracy of the engine deteriorates, the position cannot be detected, or the position is not remembered at the previous stop of the rotation of the internal combustion engine. Is done. Further, when at least one of the cooling water temperature, the battery voltage, and the fuel pressure of the internal combustion engine is low, for example, the emission of unburned gas cannot be suppressed, the exhaust HC (hydrocarbon) increases, or the cranking speed decreases. Because the sensor signal cannot be detected late or the fuel injection pulse becomes long, the injection timing is shifted, or the fuel particle diameter becomes a large spray state, so that the preceding injection is prohibited.
As a result, the startability of the internal combustion engine is improved, and the discharge of unburned gas is reliably prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic diagram showing a configuration of a spark ignition type four-cycle six-cylinder internal combustion engine to which a control device for an internal combustion engine according to an embodiment of the present invention is applied.

In FIG. 1, a crank angle sensor 1 includes a crank angle rotor 3 fixed to a crank shaft 2 of an internal combustion engine 30 and a magnetic pickup coil 4. On the outer periphery of the crank angle rotor 3, 10 [° CA
(Crank Angle: crank angle)], a tooth portion 3a is provided, and a part thereof is provided with a toothless portion 3b in which two teeth 3a are missing.

The cam angle sensor 6 comprises a cam angle rotor 8 fixed to a camshaft 7 which makes a half rotation of the crankshaft 2 of the internal combustion engine 30 and a magnet type pickup coil 9. One protrusion 8 a is provided on the outer periphery of the cam angle rotor 8.

A waveform shaping circuit 11 is connected to the crank angle sensor 1 and the cam angle sensor 6. In the waveform shaping circuit 11, both output signals from the crank angle sensor 1 and the cam angle sensor 6 are waveform-shaped at predetermined threshold values, respectively, to generate a binary pulse signal. That is, the waveform shaping circuit 1
In accordance with 1, the signal corresponding to the output signal of the crank angle sensor 1 by the tooth portion 3a excluding the missing tooth portion 3b of the crank angle rotor 3
0 [° CA], a crank angle signal NE is generated, and a cam angle sensor 6 by a projection 8a of the cam angle rotor 8 is formed.
A reference position signal G for each 720 [° CA] corresponding to the output signal is generated.

A microcomputer 20 is connected to the waveform shaping circuit 11. The microcomputer 20 receives the crank angle signal NE and the reference position signal G from the waveform shaping circuit 11 and receives 360 [° CA].
Each reference position is detected. In the present embodiment, as described later, the compression TDC in the combustion cycle of the # 1 cylinder and the # 4 cylinder of the internal combustion engine 30 is detected.

The microcomputer 20 includes a CPU as a central processing unit for executing various known arithmetic processing, a ROM for storing a control program, and an R for storing various data.
It is configured as a logical operation circuit including an AM, a B / U (backup) RAM, an input / output circuit, and a bus line connecting them. And the microcomputer 2
0, the engine speed NE is determined based on the crank angle signal NE.
Is calculated. The microcomputer 20 includes:
In addition, an intake pressure signal from the intake pressure sensor 12, a cooling water temperature signal from the water temperature sensor 13, and the like are input as various types of sensor information.

On the other hand, injectors (fuel injection valves) 31A to 31F are provided in the intake pipes (not shown) of the # 1 cylinder (first cylinder) to # 6 cylinder (sixth cylinder) of the internal combustion engine 30. . Then, in the microcomputer 20, the injectors 31A to 31A based on the detection results of the various sensor information.
The fuel injection amount by F is calculated, and the injectors 31A to 31F are driven by the calculation signal (fuel injection signal). Thereby, in the injectors 31A to 31F,
Independent injection of fuel is performed in a predetermined cylinder order (in order of # 1 cylinder → # 2 cylinder → # 3 cylinder → # 4 cylinder → # 5 cylinder → # 6 cylinder → # 1 cylinder). The igniter 32 drives an ignition plug (not shown) of each cylinder. The microcomputer 20 obtains an ignition signal based on detection results of various types of sensor information and outputs the ignition signal to the igniter 32.
Based on the ignition signal, the ignition plug is driven in a predetermined cylinder order (the same order as the injectors 31A to 31F), and a spark is generated.

A battery 14 is connected to the microcomputer 20 via an ignition switch 15. The ignition switch 15 has “OF
A switching position of “F”, “ON”, and “START” is provided. When the ignition switch 15 is switched from the “OFF” position to the “ON” position by a key (not shown), the microcomputer 1
4, the microcomputer 20 is started up and the CPU in the microcomputer 20
Various control programs are executed. When the ignition switch 15 is switched to the “START” position, in addition to the power supply to the microcomputer 20, the power is supplied from the battery 14 to the starter motor 16, and the initial rotation is given to the internal combustion engine 30 in a stopped state. Is done.

Next, a crank angle signal NE in a spark-ignition type four-cycle six-cylinder internal combustion engine 30 to which the control device for an internal combustion engine according to one embodiment of the present invention is applied.
The timing chart of FIG. 2 showing the relationship between the reference position signal G and the combustion cycle of each cylinder will be described below.

The crank counter CCRNK shown in FIG.
With the rotation of the crankshaft 2 of the internal combustion engine 30
Once every 10 [° CA] from the crank angle sensor 1
Once every three edges of the crank angle signal NE output at
Rate, ie, incremented by 30 [° CA],
Set to a predetermined value by the compression TDC of # 1 cylinder and # 4 cylinder.
It is. The value of the crank counter CCRNK is 2
Hexadecimal digits are used, and in the following description,
Change the value of the crank counter CCRNK to (xx)₁₆Notation like
Put on. Note that the crank counter CCRNK is
When the power to the computer 20 is turned on (00)₁₆Initialize to
Then, the value of the crank counter CCRNK is
After the microcomputer 20 is started, every 30 [° CA]
To (00) ₁₆, (01)₁₆, (02)₁₆,···As
Is incremented.

The time t0 in FIG. 2 is the rotation start time of the internal combustion engine 30, and the time t0 to time t1 are the crank angle signal N.
The time t2 during the mask period of E and the reference position signal G indicates the time when the reference position is first detected after the internal combustion engine 30 starts rotating. Note that the crank angle signal NE at the start of rotation of the internal combustion engine 30 is "P1 (in FIG. 2, 660 [° C
A]) ”is“ P2 (690 [° C. in FIG. 2) of the crank angle signal NE when the rotation of the internal combustion engine 30 last stopped.
A]) ”is reversed by 30 [° CA]. Further, the value of the crank counter CCRNK at the previous stop of the rotation of the internal combustion engine 30 is (1A) ₁₆ , and B / UR
AM stores # 4 cylinder, # 5 cylinder, and # 6 cylinder as corresponding specific cylinder information.

In FIG. 2, the rotation of the internal combustion engine 30 is started at time t0. That is, at time t0, the ignition switch 15 is switched from the "OFF" position to the "ON" and "ST" positions.
The position is switched to the "ART" position, and the starter motor 16 is started. At this time t0, the previous internal combustion engine 30
When the rotation of the cylinder is stopped, fuel is simultaneously injected into the specific cylinders # 4, # 5, and # 6 stored in the B / URAM.

Here, from time t0 to time t1, the crank angle signal NE and the reference position signal G are masked for a certain period (for example, 100 to 150 [ms: milliseconds]) so that cylinder determination is not performed. Is done. This is because when the crank angle sensor 1 and the cam angle sensor 6 are constituted by a magnet type pickup coil as in this embodiment,
This is because the signal detection accuracy at a minute rotation speed (for example, 20 [rpm] or less) is reduced. For this reason, in the present embodiment, the predetermined period immediately after the start of the rotation of the internal combustion engine 30 is set as the masking period of the detection signal. Immediately after the start of the rotation of the internal combustion engine 30, the crank angle signal NE
It is also conceivable that an erroneous detection occurs in the reference position signal G.

Then, at time t1 when the mask period has elapsed, a pre-injection (hereinafter referred to as "Pre-injection") shown in FIG.
The execution of the control routine is started. Thereafter, the first cylinder discrimination is performed at time t2, and the compression TDC of the # 4 cylinder is performed.
Is detected. At this time t2, the crank counter CCRNK is set to (10) ₁₆ , and the difference between the crank counter CCRNK and the actual crank angle caused by the reversal of the crank angle ("P2" → "P1") or the mask period is detected. Will be resolved. Then, the microcomputer 20 generates an ignition signal IGt by setting the ignition timing, and at time t3 (the compression ATDC of the # 4 cylinder (After Top D
At ead Center: after top dead center) 10 [° CA]), a spark is generated in the ignition plug of the # 4 cylinder by the igniter 32.

At this time, the first explosion occurs because the fuel is supplied to the # 4 cylinder by the pre-injection and is being sucked. Thereafter, normal ignition control is performed after the second ignition, and a spark is generated at the compression TDC of each cylinder.
After time t2, the fuel supply is shifted to the independent fuel supply. The starting cylinder of this independent injection is at time t2
This is the # 1 cylinder for which no pre-injection has been performed, and after the first independent injection has been performed for this # 1 cylinder,
Independent injection is executed in the order of cylinder → # 3 cylinder → # 4 cylinder →.

Next, based on the flowchart of FIG. 3 showing the processing procedure of the pre-injection control in the CPU in the microcomputer 20 used in the control device for the internal combustion engine according to one embodiment of the present invention. This will be described with reference to the timing chart of FIG. In addition,
This pre-injection control routine uses the starter motor 16
Is driven and the pulse signal from the crank angle sensor 1 is input every 10 [° CA] until the rotational position of the internal combustion engine 30 is determined.
It is repeatedly executed in PU.

In FIG. 3, in step S101, the
Update of the rank counter CCRNK is executed. In addition,
The initial value of the crank counter CCRNK is
Stored in the storage area of the B / URAM in the computer 20
Value at the time when the rotation of the internal combustion engine 30 was stopped (the actual value
In the embodiment, (1A) shown in FIG.₁₆) Is set. So
When power is supplied to the microcomputer 20,
(00) ₁₆Is initialized to
30 ° C. of the crankshaft 2 of the internal combustion engine 30
A] (00)₁₆, (01)₁₆, (02)₁₆, ...
And the compression TDC of the # 1 cylinder
(00) as the predetermined value₁₆At compression TDC of # 4 cylinder
As a constant value (10)₁₆Is set to

Here, the position of the missing tooth of the crank angle signal NE due to the missing tooth portion 3b of the crank angle rotor 3 of the crank angle sensor 1 is set immediately before the compression TDC of the # 1 cylinder and # 4 cylinder every 360 [° CA]. Is detected. The edge position of the reference position signal G by the projection 8a of the cam angle rotor 8 of the cam angle sensor 6 is the compression TDC of the # 1 cylinder every 720 [° CA].
Detected immediately before. Therefore, by detecting both the missing tooth position of the crank angle signal NE and the edge position of the reference position signal G, it is possible to determine the compression TDC of the # 1 cylinder. Further, the missing tooth position of the crank angle signal NE is determined,
Since the edge position of the reference position signal G is not detected, # 4
It can be determined as the compression TDC of the cylinder.

Next, the processing shifts to step S102, where the Pre-in
It is determined whether jection is permitted. Step S
In 102, if at least one of the following conditions is satisfied, Pre-injection is not permitted. This condition may be a malfunction of the crank angle sensor, the cam angle sensor, the B / URAM, or a condition that the cooling water temperature of the internal combustion engine 30 is lower than a predetermined value, the battery voltage is lower than a predetermined value, the fuel pressure is lower than a predetermined value,
Examples include cylinders for which injection has already been performed.

Here, when the crank angle sensor 1 is abnormal, the positional accuracy during rotation of the internal combustion engine 30 is extremely deteriorated, and when the cam angle sensor 6 is abnormal,
Since the position of the internal combustion engine 30 during rotation cannot be detected, the Pre-
Injection should be prohibited. When the B / URAM in the microcomputer 20 is abnormal,
Pre-injection should be prohibited because there is no position memory when the rotation of the internal combustion engine 30 last stopped.

Further, as described above, the previous internal combustion engine 3
The accuracy of position storage at the time of rotation stop of 0 is not good. in addition,
When the cooling water temperature of the internal combustion engine 30 is low, for example, 10 ° C. or less, it is necessary to set a long fuel injection pulse. For example, it is designed so that the injection is terminated before an intake valve (not shown) opens. However, if the fuel is not directly absorbed into the cylinder, the fuel becomes wet, and the exhaust HC increases due to the discharge of the unburned gas. Also, when the cooling water temperature is low, the cranking speed is usually low, so that the crank angle signal from the crank angle sensor 1 in the initial stage of starting cannot be detected, and the position detection error increases. For this reason, pre-injection should be prohibited.

The battery voltage is, for example, 8
If it is lower than [V] or less, the cranking speed becomes slow and the sensor signal may not be detected.
Injection should be prohibited. Further, when the fuel pressure is low, for example, 200 [kPa] or less, the fuel injection pulse needs to be lengthened, and the fuel particle diameter also increases. , Pre-injection should be prohibited.

If the determination condition of step S102 is satisfied, that is, if all of the above conditions are not satisfied, the pre-inject
ion is permitted and the process proceeds to step S103, where the Pre-inject
The cylinder for which ion is to be executed is selected. That is, it is determined which cylinder the fuel injection timing of the current crank counter CCRNK matches. This Pre-injectio
n The timing is, for example, the compression ATDC 90 of each cylinder.
[° CA] is set to exhaust ATDC 90 [° CA]. In this embodiment, it is determined that the condition is satisfied.
# 4 cylinder, # 5 cylinder and # 6 cylinder.

Next, the process proceeds to step S104, where Pre-injection is executed for the # 4 cylinder, # 5 cylinder and # 6 cylinder selected in step S103. Then, the flow shifts to step S105, where the cylinder in which the pre-injection has been executed is stored, and this routine ends. By executing the processing in step S105 described above, when this routine is operated at the next input timing of the pulse signal from the crank angle sensor 1, the # 4 cylinder, the # 5 cylinder, and the
It is possible to prevent the fuel from being pre-injected again into the six cylinders.

In this embodiment, as described above, when the crank counter CCRNK reaches (10) ₁₆ , the rotational position is determined, the ignition operation is started, and combustion starts from the # 4 cylinder. . Also, the crank counter C
When CRNK becomes (10) ₁₆ , the cylinder becomes # 1. When CCRNK becomes (12) ₁₆ , the cylinder becomes # 2. When CCRNK becomes (16) ₁₆ , the cylinder becomes # 3. , Fuel supply by independent injection is performed.

As described above, the control device for an internal combustion engine according to the present embodiment includes a crank angle sensor 1 for detecting a rotational position of a crankshaft 2 of an internal combustion engine 30 including a plurality of cylinders (# 1 to # 6 cylinders). A cam angle sensor 6 for detecting a rotation position of the camshaft 7 of the internal combustion engine 30 and a rotation position corresponding to a combustion cycle of each cylinder of the internal combustion engine 30 are determined based on output signals from the crank angle sensor 1 and the cam angle sensor 6. And a B / URAM in the microcomputer 20 as position storage means for storing the rotational position of the internal combustion engine 30 determined by the position determination means. Before the cylinder discrimination in which the rotational position of the internal combustion engine 30 is determined by the above, the engine is started based on the rotational position of the internal combustion engine 30 stored in the position storage means. Prior injection achieved by the microcomputer 20 for controlling the fuel injection (Pre-injectio
n) Pre-injection prohibition means achieved by the microcomputer 20 for prohibiting fuel injection at the time of starting by the preceding injection control means based on predetermined conditions. In the preceding injection prohibiting means achieved by the microcomputer 20 of the control device for an internal combustion engine of the present embodiment, the predetermined condition is that at least one of the crank angle sensor 1, the cam angle sensor 6, and the B / URAM is abnormal. At this time, or when at least one of the cooling water temperature, the battery voltage, and the fuel pressure of the internal combustion engine 30 is equal to or less than a predetermined value, the fuel injection at the time of starting is prohibited.

That is, fuel injection at the time of starting the internal combustion engine 30 having a plurality of cylinders is prohibited based on predetermined conditions. As specific predetermined conditions, at least one of the crank angle sensor 1, the cam angle sensor 6, and the B / URAM
When one of them is abnormal, the position accuracy at the time of rotation of the internal combustion engine 30 is deteriorated, the position cannot be detected, or there is no position memory at the time of the previous stop of the rotation of the internal combustion engine 30.
Pre-injection is prohibited because injection does not always ensure ignition. The internal combustion engine 3
When at least one of the cooling water temperature, the battery voltage, and the fuel pressure is low, the emission of unburned gas cannot be suppressed and the exhaust HC increases, the cranking speed is low, the sensor signal cannot be detected, or the fuel Pre-injection is prohibited because the injection timing is shifted or the fuel particle diameter becomes large due to the long injection pulse. Accordingly, if all of the predetermined conditions are not satisfied before the cylinder discrimination, the fuel injection at the time of starting is prohibited. Therefore, it is possible to reliably prevent the discharge of unburned gas while improving the startability of the internal combustion engine 30. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a spark ignition type four-cycle six-cylinder internal combustion engine to which a control device for an internal combustion engine according to an embodiment of the present invention is applied.

FIG. 2 is a timing chart showing a relationship between a crank angle signal and a reference position signal in FIG. 1 and a combustion cycle of each cylinder.

FIG. 3 is a diagram showing a CP in an ECU used in a control device for an internal combustion engine according to an embodiment of the present invention;
9 is a flowchart illustrating a processing procedure of Pre-injection control in U.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crank angle sensor 2 Crankshaft 6 Cam angle sensor 7 Camshaft 20 Microcomputer 30 Internal combustion engine

Continued on front page F term (reference) 3G084 BA15 CA01 DA09 DA10 DA30 DA32 EA07 EA11 EB22 FA00 FA03 FA20 FA36 FA38 FA39 3G301 HA01 JA00 JA26 JB01 JB05 KA01 KA02 MA19 MA21 NA08 NC01 NC08 NE00 NE23 PB08Z PE00B PE00Z PE03Z03 PE03Z03Z03

Claims (2)

[Claims] 1. A crank angle sensor for detecting a rotational position of a crankshaft of an internal combustion engine having a plurality of cylinders, a cam angle sensor for detecting a rotational position of a camshaft of the internal combustion engine, the crank angle sensor and the cam angle Position determination means for determining a rotation position corresponding to a combustion cycle of each cylinder of the internal combustion engine based on an output signal from a sensor; andposition storage means for storing the rotation position of the internal combustion engine determined by the position determination means. Prior to the cylinder discrimination in which the rotation position of the internal combustion engine is determined by the position determination means, a preceding injection control means for controlling fuel injection at the time of starting based on the rotation position of the internal combustion engine stored in the position storage means. And a preceding injection prohibiting means for prohibiting fuel injection at the time of starting by the preceding injection control means based on a predetermined condition. Combustion engine control device. 2. The pre-injection prohibiting means sets the predetermined condition when at least one of the crank angle sensor, the cam angle sensor, and the position storage means is abnormal, or a cooling water temperature of the internal combustion engine and a battery voltage. The control device for an internal combustion engine according to claim 1, wherein when at least one of the fuel pressures is equal to or less than a predetermined value, fuel injection at the time of starting is prohibited.