JPH0849638A - Controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent ignition performance in the overlap-electrification from being deteriorated by varying the current value for performing over current protection according to the driving state. CONSTITUTION:Ignition signals are output from ignition output circuits 14, 15, 16, and values of current to flow through a plurality of ignition coils 31, 32, 33 are detected by a single current detecting circuit composed of transistors Tr1, Tr2, Tr3 and a resistance R3. The electrification is controlled in relation to a plurality of ignition coils 31, 32, 33 by a current control means composed of diodes D1, D2, D3, resistances R1, R2 and an operational amplifier OA1 on the basis of an allowable current value at which excess current is protected to the current values. When the electrification periods to respective ignition coils 31, 32, 33 are overlapped, the allowable current value in the current control means is corrected by a correcting means composed of an over current control switching port 10a of a microcomputer 10, a diode D4 and a resistance R4 so as to match to the increase of the current value at that time.

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, which outputs an ignition signal corresponding to a plurality of ignition coils provided corresponding to a plurality of cylinders of an internal combustion engine.

[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. 61-40462 is known. This document discloses a technique of improving ignition performance by reducing the resistance of an ignition coil in an ignition control device using a microcomputer. At this time, an overcurrent protection circuit is provided to protect the transistor of the ignition output circuit.

[0003]

However, in order to reduce the cost, it is required to realize the current detection of a plurality of ignition coils by a common current detection circuit, and a circuit configuration as shown in FIG. 6 is desired. There is.

In FIG. 6, reference numeral 1 denotes an ECU (Electronic C
ontrol unit: electronic control unit), and the ECU 1 mainly includes the microcomputer 10 and the waveform shaping circuits 11 and 1.
2, input circuit 13, ignition output circuits 14, 15, 16, transistors Tr1, Tr2, Tr3, diodes D1, D2, D3
, Resistors R1, R2, R3, and an operational amplifier OA1.
Here, the resistor R3 is one current detecting resistor for detecting the current value from the ignition output circuits 14, 15 and 16, and the voltage applied to this resistor R3 is the non-inverting (+) input terminal of the operational amplifier OA1. Applied to the side. Also, VO is EC
This is the reference voltage set inside U1, and the reference voltage VO
Is divided by resistors R1 and R2, and the voltage applied to resistor R2 is applied to the inverting (-) input terminal side of operational amplifier OA1.

The microcomputer 10 of the ECU 1 is provided with a rotation signal of the internal combustion engine from the distributor 2,
The cylinder discrimination signal is passed through the waveform shaping circuits 11 and 12, and
Various sensor signals and the power supply voltage VB of the battery are input via the input circuit 13. Then, from the microcomputer 10 of the ECU 1, an ignition output circuit is provided to the bases of the transistors Tr1, Tr2, Tr3 connected in series to the primary side of the ignition coils 31, 32, 33 for each cylinder of the internal combustion engine having three cylinders. An ignition signal is output from 14, 15, 16 at a predetermined timing.

In order to protect the transistors Tr1, Tr2, Tr3 from overcurrent, when the voltage applied to the resistor R3 exceeds the voltage applied to the resistor R2, the bases of the transistors Tr1, Tr2, Tr3 are passed through the diodes D1, D2, D3. Current flows to the operational amplifier OA1 side. In this way, the transistors Tr1, Tr2, Tr3 are turned off for overcurrent protection,
The current flowing through the primary side of the ignition coils 31, 32, 33 is reduced.

By the way, in the above circuit configuration, when the internal combustion engine is rotated at a high speed and the overlap energization state occurs in which a part of the energization periods of the ignition signals to the plurality of ignition coils overlap, the current flowing through the ignition coils is a desired current. There was a problem that the overcurrent protection worked before reaching the value and the ignition performance deteriorated.

Therefore, the present invention has been made in order to solve such a problem, and an object thereof is to provide a control device for an internal combustion engine capable of preventing deterioration of ignition performance at the time of overlapping energization.

[0009]

According to a first aspect of the present invention, there is provided an internal combustion engine control device, comprising: a plurality of ignition coils respectively provided for a plurality of cylinders of an internal combustion engine; and an ignition corresponding to the plurality of ignition coils. A plurality of ignition output circuits that output signals, a current detection circuit that detects current values flowing in the plurality of ignition coils, and energize the plurality of ignition coils based on the current values detected by the current detection circuit A current control means for controlling and a correction means for correcting the energization control by the current control means when the energization periods for the plurality of ignition coils by the plurality of ignition output circuits overlap.

A control device for an internal combustion engine according to claim 2 is
In addition to the means provided in claim 1, the current control means controls energization so that the current value when the energization of the ignition coil is cut off reaches a predetermined target current value.

A control device for an internal combustion engine according to claim 3 is
In addition to the means provided in claim 1 or claim 2, the current control means cuts off energization when the current value detected by the current detection circuit reaches a predetermined target current value.

A control device for an internal combustion engine according to claim 4 is
In addition to the means provided in claim 1, claim 2 or claim 3, the correction means invalidates the energization control by the current control means when the engine speed of the internal combustion engine is higher than a predetermined speed. Is.

A control device for an internal combustion engine according to claim 5 is
In addition to the means provided in claim 1, claim 2 or claim 3, the correction means is such that the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than a predetermined voltage. When it is high, the energization control by the current control means is invalidated.

A control device for an internal combustion engine according to claim 6 is
In addition to the means provided in claim 2 or claim 3, the correction means increases the target current value when the engine speed of the internal combustion engine is higher than a predetermined speed as compared with other cases. .

A control device for an internal combustion engine according to claim 7 is
In addition to the means provided in claim 2 or claim 3, the correction means, when the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than a predetermined voltage, the target. The current value is made higher than in other cases.

[0016]

According to the present invention, an ignition signal is output from the ignition output circuit corresponding to each ignition coil of a plurality of cylinders of the internal combustion engine, and the current value flowing through the plurality of ignition coils is detected by the current detection circuit. Based on the current value detected by the current detection circuit, the current control means controls the energization of the plurality of ignition coils. Here, when the energization periods of the ignition coils from the plurality of ignition output circuits overlap, the energization control by the current control unit is corrected by the correction unit so as to be commensurate with the increase in the current value at that time.

In the current control means of the control device for an internal combustion engine according to a second aspect, in addition to the operation of the first aspect, the current value when the ignition coil is de-energized is a predetermined target current value, that is, overcurrent protection. Energization is controlled so as to reach the allowable current value.

In the current control means of the control device for an internal combustion engine according to a third aspect, in addition to the operation of the first or second aspect, the current value detected by the current detection circuit is a predetermined target current value, that is, an overcurrent. When the allowable current value for current protection is reached, energization is cut off.

According to the correction means of the control device for an internal combustion engine of claim 4, in addition to the operation of claim 1, claim 2 or claim 3, the current control means when the engine speed of the internal combustion engine is higher than a predetermined speed. Energization control by is invalid, that is, overcurrent protection is ignored in this region.

According to the correction means of the control device for an internal combustion engine of claim 5, in addition to the operation of claim 1, claim 2 or claim 3, the engine speed of the internal combustion engine is higher than a predetermined speed and the ignition is performed. When the power supply voltage to the coil is higher than the predetermined voltage, the energization control by the current control means is invalid, that is, the overcurrent protection is ignored in this region.

In the correction means of the control device for an internal combustion engine according to claim 6, in addition to the operation of claim 2 or 3, the target current value when the engine speed of the internal combustion engine is higher than a predetermined speed,
That is, the allowable current value for overcurrent protection in this region is made higher than in other cases.

According to the correction means of the internal combustion engine control device of claim 7, in addition to the operation of claim 2 or claim 3, the engine speed of the internal combustion engine is higher than a predetermined speed, and the power supply voltage to the ignition coil is higher. Is higher than a predetermined voltage, the target current value, that is, the allowable current value for overcurrent protection in this region is made higher than in other cases.

[0023]

EXAMPLES The present invention will be described below based on specific examples.

FIG. 1 is a circuit diagram showing an electrical configuration of a control device for an internal combustion engine according to an embodiment of the present invention. It should be noted that the same reference numerals and symbols are given to those having the same configuration or corresponding portions as those of the above-described conventional apparatus.

In FIG. 1, reference numeral 1 denotes an ECU, and
1 is mainly a microcomputer 10, waveform shaping circuits 11, 12, an input circuit 13, an ignition output circuit 14, 1.
5, 16, transistors Tr1, Tr2, Tr3, diodes D1, D2, D3, D4, resistors R1, R2, R3, R4, and an operational amplifier OA1. Here, the resistor R3 is the ignition output circuit 1
It is one current detecting resistor for detecting the current value from 4, 15, 16 and the voltage at the point B (potential at the point B) applied to this resistor R3 is on the non-inverting (+) input terminal side of the operational amplifier OA1. Applied to. VO is a reference voltage set inside the ECU 1, and the reference voltage VO is divided by the resistors R1 and R2 and the voltage at the point A applied to the resistor R2 (potential at the point A).
Is applied to the inverting (-) input terminal side of the operational amplifier OA1.

In the microcomputer 10 of the ECU 1, the rotation signal of the internal combustion engine from the distributor 2,
The cylinder discrimination signal is passed through the waveform shaping circuits 11 and 12, and
Various sensor signals and the power supply voltage VB of the battery are input via the input circuit 13. Then, from the microcomputer 10 of the ECU 1, an ignition output circuit is provided to the bases of the transistors Tr1, Tr2, Tr3 connected in series to the primary side of the ignition coils 31, 32, 33 for each cylinder of the internal combustion engine having three cylinders. Ignition signals 1, 2, and 3 are output from 14, 15, and 16 at predetermined timings. Here, in order to protect the transistors Tr1, Tr2, Tr3 from overcurrent, when the voltage at the point B (potential at the point B) applied to the resistor R3 exceeds the voltage at the point A (potential at the point A) applied to the resistor R2, the diodes D1, D2. , D3 through transistors Tr1, Tr2,
The base current of Tr3 flows to the operational amplifier OA1 side. In this way, the transistors Tr1, Tr2, Tr3 are turned off for overcurrent protection, and the current flowing through the primary side of the ignition coils 31, 32, 33 is reduced.

The difference between the device of this embodiment and the conventional device is that the microcomputer 10 includes an overcurrent control switching port 10.
a, a diode D4 and a resistor R4 are provided, and the overcurrent control switching port 10a is connected to a point A, which is an intermediate point between the resistors R1 and R2, via the diode D4 and the resistor R4 connected in series.

Next, the microcomputer 10 used in the control device for the internal combustion engine according to the embodiment of the present invention.
The processing procedure of the internal CPU will be described based on the flowchart of FIG. 2 and with reference to the time chart of FIG.

After various inputs are read in step S101, the process proceeds to step S102, and it is determined whether or not it is the overlap energization area. When the determination condition of step S102 is not satisfied, that is, when the internal combustion engine is running at low speed, the ignition signals 1, 2,
When the current-carrying periods of 3 do not overlap and the current-carrying period is not in the overlap current-carrying region, the process proceeds to step S103. In step S103, the overcurrent control switching port 10a is set to Low.
As a result, the potential at point A in FIG. 1 for overcurrent protection is set to a potential equivalent to 8 A during normal energization (see potential at point A during normal energization in FIG. 3), and this program ends.

On the other hand, when the determination condition of step S102 is satisfied, that is, the engine speed of the internal combustion engine is, for example, 40.
A high rotation of more than 00 rpm and a plurality of ignition coils 31,
When it is in the overlap energization region where the energization periods of the ignition signals 1, 2, and 3 for the parts 32 and 33 overlap with each other so as to partially overlap each other, the process proceeds to step S104. In step S104, the overcurrent control switching port 10a is set to Hi for overcurrent control,
For overcurrent protection, the potential at point A in Fig. 1 is 8A when the current is normally applied.
The potential is changed from the equivalent to the potential equivalent to 12 A at the overlap energization (see the potential at the point A at the overlap energization in FIG. 3), and this program is terminated.

With this control, the current on the primary side of the plurality of ignition coils 31, 32, 33 increases during overlap energization, and even if the potential at point B in FIG. 1 rises, it reaches the potential at point A. Since it does not occur, overcurrent protection does not work, and it is possible to prevent a decrease in the current flowing through the ignition coils 31, 32, 33.

The overlap energization region is an engine speed Ne which is a rotation signal of the internal combustion engine which is an input signal to the ECU 1.
(Rpm) and the power supply voltage VB (V) of the battery, etc., and can be arbitrarily set. Here, FIG. 4 is a map showing an overcurrent control change region (hatched portion) with the engine speed Ne (rpm) as a parameter, and FIG. 5 shows the engine speed Ne (rpm) and the power supply voltage VB (V). 4 is a map showing an overcurrent control change region (hatched portion) with the parameter as a parameter.

As described above, the control device for an internal combustion engine according to the present embodiment has a plurality of ignition coils 31, 32, 33 provided respectively corresponding to a plurality of cylinders of the internal combustion engine, and a plurality of ignition coils 31, 32, 32. 33, a plurality of ignition output circuits 14, 15, 16 for outputting ignition signals 1, 2, 3 and transistors Tr1, Tr2, Tr3 for detecting current values flowing in the plurality of ignition coils 31, 32, 33, and One common current detection circuit composed of a resistor R3, and a plurality of ignition coils 31, 3 based on the current value detected by the current detection circuit.
Diodes D1, D2, D3 for controlling energization of 2, 33
, The resistors R1 and R2 and the operational amplifier OA1 and the plurality of ignition output circuits 14, 15 and 16 for the plurality of ignition coils 31, 32 and 33 for the same energization period, the current control means energizes the current. Overcurrent control switching port 1 of microcomputer 10 for correcting control
0a, a diode D4 and a resistor R4 are provided as correction means, which can be the embodiment of claim 1.

Therefore, the ignition output circuit 14, corresponding to the ignition coils 31, 32, 33 of the plurality of cylinders of the internal combustion engine,
Ignition signals 1, 2 and 3 are output from 15 and 16, and the current value flowing through the plurality of ignition coils 31, 32 and 33 is detected by one current detection circuit composed of transistors Tr1, Tr2, Tr3 and resistor R3. Based on the allowable current value for overcurrent protection against the current value, the current control means including the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier OA1 controls the energization of the plurality of ignition coils 31, 32, 33. When the energization periods of the ignition coils 31, 32, 33 from the plurality of ignition output circuits 14, 15, 16 are overlapped, the correction means including the overcurrent control switching port 10a of the microcomputer 10, the diode D4 and the resistor R4 is used. The allowable current value in the current control means is corrected so as to correspond to the increase in the current value at that time.

Therefore, for example, even when the internal combustion engine is operating at a high speed and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the current flowing through the ignition coil is desired. Before the current value is reached, the overcurrent protection by the allowable current value does not work, and the deterioration of ignition performance is prevented.

Further, the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier O of the control device for the internal combustion engine of the present embodiment.
The current control means composed of A1 includes ignition coils 31, 32,
It is also possible to perform energization control so that the current value when the energization to 33 is cut off reaches a predetermined target current value, and this can be the embodiment of claim 2.

Therefore, for example, even when the internal combustion engine is operating at a high rotation speed and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the current flowing through the ignition coil is predetermined. Since the allowable current value, which is the target current value, can be reached without fail and the overcurrent protection does not work before that, it is possible to prevent deterioration of the ignition performance.

The current control means comprising the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier OA1 of the control device for the internal combustion engine of this embodiment is composed of the transistors Tr1, T2.
When the current value detected by the current detection circuit composed of r2, Tr3 and the resistor R3 reaches a predetermined target current value, the energization can be cut off, which can be the embodiment of claim 3.

Therefore, for example, even when the internal combustion engine is operating at a high speed and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the current flowing through the ignition coil is predetermined. Since the allowable current value, which is the target current value, can be reached without fail and the overcurrent protection does not work before that, it is possible to prevent deterioration of the ignition performance.

Furthermore, the overcurrent control switching port 10 of the microcomputer 10 of the internal combustion engine control apparatus according to the present embodiment.
The correction means composed of a, the diode D4 and the resistor R4 is
When the engine speed of the internal combustion engine is higher than a predetermined speed, the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier O
The energization control by the current control means composed of A1 can be invalidated, and this can be the embodiment of claim 4.

Therefore, for example, when the internal combustion engine is operating at a high speed and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the overcurrent protection is released and the current flows to the ignition coils. Since the current can surely reach the desired current value, it is possible to prevent the ignition performance from deteriorating.

Furthermore, the overcurrent control switching port 1 of the microcomputer 10 of the control device for the internal combustion engine of this embodiment.
0a, the diode D4 and the resistor R4, the correction means is such that the engine speed of the internal combustion engine is higher than a predetermined speed.
Also, the power supply voltage V for the ignition coils 31, 32, 33
When B is higher than a predetermined voltage, it is possible to invalidate the energization control by the current control means consisting of the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier OA1. This can be the embodiment of claim 5. it can.

Therefore, for example, the operating state is such that the internal combustion engine rotates at a high speed, and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap is achieved, and the power supply voltage to the ignition coils at that time is predetermined. When the voltage is higher than the voltage, the overcurrent protection is released, and the current flowing through the ignition coil can surely reach the desired current value, so that the ignition performance can be prevented from being degraded.

In addition, the overcurrent control switching port 10 of the microcomputer 10 of the internal combustion engine controller according to the present embodiment.
The correction means composed of a, the diode D4 and the resistor R4 is
When the engine speed of the internal combustion engine is higher than a predetermined speed, the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier O
It is also possible to make the target current value by the current control means composed of A1 higher than in other cases.
Can be used as an example.

Therefore, for example, when the internal combustion engine is operating at a high speed and the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the allowable current value for overcurrent protection becomes low. The current is increased compared to other cases, and the current flowing through the ignition coil can surely reach a desired current value, so that it is possible to prevent deterioration of ignition performance.

Further, the overcurrent control switching port 10 of the microcomputer 10 of the control device for the internal combustion engine of this embodiment.
The correction means composed of a, the diode D4 and the resistor R4 is
The engine speed of the internal combustion engine is higher than a predetermined speed, and the power supply voltage VB for the ignition coils 31, 32, 33 is
Is higher than a predetermined voltage, the target current value by the current control means consisting of the diodes D1, D2, D3, the resistors R1, R2 and the operational amplifier OA1 is made higher than in other cases. It can be an example.

Therefore, for example, the operating state is such that the internal combustion engine rotates at a high speed and an overlapping energization state occurs in which a part of the energization periods of the ignition signals for a plurality of ignition coils overlap, and the power supply voltage for the ignition coils at that time is predetermined. When the voltage is higher than the voltage, the allowable current value for overcurrent protection is increased in other cases, and the current flowing through the ignition coil can surely reach the desired current value, so that it is possible to prevent the ignition performance from deteriorating.

By the way, in the above embodiment, the potential at the point A in FIG. 1 is raised at the time of overlap energization to prevent the erroneous determination of the overcurrent control. However, the present invention is not limited to this. It suffices to control the current setting value when energizing a plurality of ignition coils according to the detected current value. The potential at the point A can be arbitrarily set by changing the value of the resistor R4.

It is also possible to forcibly fix the potential at the point A to the Hi level so that the overcurrent control is not executed only during that period.

Further, by setting the potential at the point A to a predetermined potential, it is possible to achieve a fail-safe function when the ignition coils 31, 32, 33 are short-circuited.

[0051]

As described above, according to the control device for an internal combustion engine of claim 1, an ignition signal is output from the ignition output circuit corresponding to each ignition coil of a plurality of cylinders of the internal combustion engine.
The current value flowing through the plurality of ignition coils is detected by the current detection circuit, the current control means controls the energization of the plurality of ignition coils based on the current value, and the energization period of each ignition coil from the plurality of ignition output circuits is determined. When overlapping,
The energization control in the current control means is corrected by the correction means. As a result, even when the common current detection circuit is used for a plurality of ignition coils, it is possible to prevent the ignition performance from deteriorating during overlap energization.

According to the control device for an internal combustion engine of claim 2,
In addition to the effect of claim 1, the current control means further controls energization so that the current value when the energization of the ignition coil is cut off reaches a predetermined target current value, that is, an allowable current value for overcurrent protection. . As a result, the current flowing through the ignition coil can reliably reach the allowable current value, which is the predetermined target current value, regardless of the operating state, and the overcurrent protection does not work before that, thus preventing the deterioration of the ignition performance. be able to.

According to the control device for an internal combustion engine of claim 3,
In addition to the effect of claim 1 or claim 2, the current control means energizes when the current value detected by the current detection circuit reaches a predetermined target current value, that is, an allowable current value for overcurrent protection. Is cut off. As a result, the current flowing through the ignition coil can reliably reach the allowable current value, which is the predetermined target current value, regardless of the operating state, and the overcurrent protection does not work before that, thus preventing the deterioration of the ignition performance. be able to.

According to the control device for an internal combustion engine of claim 4,
In addition to the effect of claim 1, claim 2 or claim 3, further, in the correction means, when the engine speed of the internal combustion engine is higher than a predetermined speed, the energization control based on the allowable current value by the current control means is invalid, that is, , Overcurrent protection is ignored in this region. As a result, when the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the overcurrent protection is released and the current flowing through the ignition coil can surely reach the desired current value. It is possible to prevent deterioration of ignition performance.

According to the control device for an internal combustion engine of claim 5,
In addition to the effect of claim 1, claim 2 or claim 3, further, in the correction means, when the engine speed of the internal combustion engine is higher than a predetermined speed, the energization control based on the allowable current value by the current control means is invalid, that is, , Overcurrent protection is ignored in this region. As a result, when the overlapping energization state in which a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, the overcurrent protection is released and the current flowing through the ignition coil can surely reach the desired current value. It is possible to prevent deterioration of ignition performance.

According to the control device for an internal combustion engine of claim 5,
In addition to the effect of claim 1, claim 2 or claim 3, the correction means further controls the current when the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than the predetermined voltage. The energization control based on the allowable current value by the means is invalid, that is, the overcurrent protection is ignored in this region. As a result, the overlap energization state is set such that a part of the energization periods of the ignition signals for the plurality of ignition coils overlap, and if the power supply voltage for the ignition coils at that time is higher than a predetermined voltage, the overcurrent protection is released and the ignition coils are released. Since the current flowing through can reliably reach the desired current value,
It is possible to prevent deterioration of ignition performance.

According to the control device for an internal combustion engine of claim 6,
In addition to the effect of claim 2 or claim 3, the correction means further sets a target current value when the engine speed of the internal combustion engine is higher than a predetermined speed, that is, an allowable current value for overcurrent protection in this region. It will be higher than in other cases. As a result, when an overlapping energization state occurs in which the energization periods of the ignition signals for a plurality of ignition coils overlap, the allowable current value for overcurrent protection is increased compared to other cases, and the current flowing through the ignition coils is increased. Can reliably reach the desired current value, so that it is possible to prevent the ignition performance from deteriorating.

According to the control device for an internal combustion engine of claim 7,
In addition to the effect of claim 2 or claim 3, further, in the correction means, when the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than a predetermined voltage, the target current value, that is, The allowable current value for overcurrent protection in this region is made higher than in other cases. As a result, an overlapping energization state occurs in which the energization periods of the ignition signals for a plurality of ignition coils overlap, and if the power supply voltage for the ignition coils at that time is higher than the specified voltage, the allowable current value for overcurrent protection is set. Is raised in other cases, and the current flowing through the ignition coil can surely reach a desired current value, so that it is possible to prevent deterioration of ignition performance.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an electrical configuration of a control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a C in a microcomputer used in a control device for an internal combustion engine according to an embodiment of the present invention.
It is a flow chart which shows a processing procedure of PU.

FIG. 3 is an ignition signal for each ignition coil during normal energization and overlap energization of an internal combustion engine control apparatus according to an embodiment of the present invention, an A point potential and a B point potential,
It is a time chart which shows the electric current with respect to each ignition coil.

FIG. 4 is a map showing an overcurrent control change region with an engine speed Ne used as a parameter, which is used in a control device for an internal combustion engine according to an embodiment of the present invention.

FIG. 5 is a map showing an overcurrent control change region with the engine speed Ne and the power supply voltage VB used as parameters in the internal combustion engine controller according to one embodiment of the present invention.

FIG. 6 is a circuit diagram showing an electrical configuration of a conventional control device for an internal combustion engine.

[Explanation of symbols]

 1 ECU (electronic control unit) 2 Distributor 10 Microcomputer 10a Overcurrent control switching port 14, 15, 16 Ignition output circuit 31, 32, 33 Ignition coil VB Power supply voltage VO Reference voltage Tr1, Tr2, Tr3 Transistors D1, D2, D3 , D4 diode R1, R2, R3, R4 resistance OA1 operational amplifier

Claims (7)

[Claims] 1. A plurality of ignition coils respectively provided corresponding to a plurality of cylinders of an internal combustion engine, a plurality of ignition output circuits for outputting an ignition signal corresponding to the plurality of ignition coils, and the plurality of ignition coils. A current detection circuit for detecting a current value flowing through the current detection circuit, a current control means for controlling energization of the plurality of ignition coils based on the current value detected by the current detection circuit, and a plurality of the plurality of ignition output circuits. The control device for an internal combustion engine, comprising: a correction unit that corrects the energization control by the current control unit when the energization periods of the ignition coils overlap. 2. The control device for an internal combustion engine according to claim 1, wherein the current control means controls energization so that a current value when the energization of the ignition coil is cut off reaches a predetermined target current value. . 3. The internal combustion engine according to claim 1, wherein the current control means interrupts energization when the current value detected by the current detection circuit reaches a predetermined target current value. Engine control device. 4. The correction means invalidates the energization control by the current control means when the engine speed of the internal combustion engine is higher than a predetermined speed. The control device for an internal combustion engine according to one. 5. The correction means invalidates the energization control by the current control means when the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than a predetermined voltage. Claim 1 characterized by the above-mentioned.
A control device for an internal combustion engine according to claim 3. 6. The correction means increases the target current value when the engine speed of the internal combustion engine is higher than a predetermined speed as compared with other cases. A control device for an internal combustion engine as described. 7. The correction means, when the engine speed of the internal combustion engine is higher than a predetermined speed and the power supply voltage to the ignition coil is higher than a predetermined voltage, sets the target current value higher than in other cases. The control device for an internal combustion engine according to claim 2 or 3, characterized in that.