JPH0758063B2 - Ignition control device for internal combustion engine - Google Patents

Description

The present invention relates to an ignition control device for an internal combustion engine.

<Prior Art> A crank angle sensor has been conventionally used for ignition control of an internal combustion engine.

There are various types of systems that perform ignition control using a crank angle sensor, but recently, in synchronization with engine rotation, a reference is made at a predetermined crank angle position (predetermined reference position of piston) in a specific stroke of each cylinder. There is an increasing number of methods of controlling the ignition time by a microcomputer using a crank angle detecting device having only a function of outputting a pulse signal (see Japanese Utility Model Application No. 62-133304, etc.).

That is, for example, as shown in FIG. 5, the cycle of the reference pulse signal is measured, and the next cycle TF is predicted based on the previous cycle T _n-1 and the current cycle T _n . Then, the required ignition angle (ignition timing) is converted into time based on the next cycle TF, and the time τ1 from the reference point t _n to the ignition timing is obtained. Similarly, from the required energization time, the time τ from the reference point t _n until the energization of the ignition coil is started τ
Ask for 2. Then, after the elapse of τ2 from the reference point t _n , the energization of the ignition coil is started, and after the elapse of τ1, the energization is cut off to perform the ignition.

This type of system uses a sensor and an output as in the case of, for example, outputting two systems of a reference pulse signal for each reference crank angle and a unit pulse signal for each unit crank angle separately and controlling the ignition timing angle. This is because there is no need for two lines and the ignition timing control can be performed by one sensor and output line (in one pickup system), which is advantageous in terms of cost.

<Problems to be Solved by the Invention> However, when the ignition timing is configured to be time-controlled based only on the reference pulse signal as described above, the next cycle is calculated from the previous cycle T _n-1 and the current cycle T _n. In order to obtain TF, the predicted cycle TF and the actual cycle T are greatly deviated at the first rise or fall of the rotation at the time of start or sudden acceleration / deceleration where the cycle T changes abruptly, and the ignition timing control There was a problem that the system deteriorated.

Further, as described above, when the microcomputer is configured to output the ignition signal to the ignition device based on the detection signal from the crank angle sensor, it becomes impossible to control the ignition when the microcomputer is abnormal. There was also a problem that engine operation could not be continued.

The present invention has been made in view of the above problems, and is provided with a crank angle sensor having a good control system while using one pickup system (sensor and one output line system), and ignition is performed even when a microcomputer for controlling ignition timing is abnormal. An object is to provide an ignition control device that can be enabled.

<Means for Solving the Problems> Therefore, according to the present invention, as shown in FIG. 1, only in a predetermined crank angle range based on the piston top dead center of the internal combustion engine, on the same output line, for each unit crank angle. Of the crank angle sensor and an ignition control means for outputting an ignition signal to the ignition device based on the detection signal output from the crank angle sensor. Mask signal output means for masking the detection signal and outputting a mask pulse signal in the predetermined crank angle range in which a detection signal for each crank angle is output, and an abnormality in the ignition control means is detected, and the ignition control is performed when an abnormality is detected. Fail-safe for outputting to the ignition device a mask pulse signal from the mask signal output means as an ignition signal instead of the ignition signal from the means. Means
An ignition control device for an internal combustion engine is provided.

<Operation> In this configuration, the crank angle sensor outputs a detection signal on the same output line.
The detection signal is output for each unit crank angle only within a predetermined crank angle range based on the piston top dead center. Then, the ignition control means outputs an ignition signal to the ignition device based on the detection signal output from the crank angle sensor only within a predetermined crank angle range.

Therefore, if the predetermined crank angle range in which the detection signal for each unit crank angle is output is set so as to include, for example, the engine required ignition timing change range, the ignition control means outputs the detection signal for each unit crank angle. The angle of the ignition timing can be controlled on the basis of the ignition timing, and the desired ignition timing can be reliably captured and ignited even if the engine rotation suddenly changes. Further, since the output line is one system, the structure of the crank angle sensor is simple.

On the other hand, the mask signal output means masks the detection signal output from the crank angle sensor within a predetermined crank angle range and outputs a mask pulse signal, and the fail-safe means outputs an ignition control signal when an abnormality is detected in the ignition control means. Instead of the ignition signal from the control means, the mask pulse signal from the mask signal output means is output to the ignition device as an ignition signal so that ignition control is performed based on the mask pulse signal.

Therefore, even when the ignition timing control cannot be performed by the ignition control means, the ignition can be performed in synchronization with the mask pulse signal from the mask signal output means.

<Examples> Examples of the present invention will be described below.

FIG. 2 shows an ignition control device according to the present invention.

Here, the crank angle sensor 10 is 1/2 per engine revolution.
Signal disk plate 12 on rotating shaft (eg distributor shaft or cam shaft) 11
The signal disk plate 12 is formed with slit groups 13 of several cylinders (four cylinders in this embodiment, which are four cylinders) at equal intervals in the circumferential direction. Then, a light projector (LED) 15 and a light receiver (photodiode) 16 that constitute the photoelectric pickup 14 are provided with the signal disc plate 12 sandwiched therebetween, and light from the light projector 15 is transmitted through a plurality of slits that constitute the slit group 13. A detection signal is output based on the light receiving signal when passing.

Here, as shown in FIG. 3, the slit group 13 includes the piston top dead center (crank angle 18 in the case of a four-cylinder engine) of each cylinder.
Every 0 °) Crank angle range from 75 ° before to 5 ° before top dead center (range of 70 ° crank angle before compression top dead center of each cylinder,
In the required ignition timing control range), slits corresponding to a crank angle of 1 °, which is a unit crank angle, are also provided at intervals of 1 °, and a detection signal (slit detection) by light passing through the slit is detected. Signal)
The pulse signal is such that rising and falling are alternately repeated at every 1 ° of crank angle. That is, the crank angle sensor 10 is configured to output a detection signal for each crank angle of 1 ° only within the range of 70 ° before the top dead center of the piston.

The signal from the crank angle sensor 10 is input to the mask circuit 17 as the mask signal output means, and is also input to the CLK terminal of the microcomputer 18 as the ignition control means, and the mask circuit 17 outputs the signal from the crank angle sensor 10. A mask pulse signal obtained by masking the detection signal is output to the edge sense IRQ (a terminal for executing an interrupt routine synchronized with the falling edge of the mask pulse signal) of the microcomputer 18.

The mask circuit 17 outputs a mask pulse signal whose rising edge is the beginning of the slit group 13 and falling edge is the end of the slit group 13.

The mask circuit 17 is configured as shown in FIG.
First, the detection signal (1 ° signal) from the crank angle sensor 10
However, when the reference measurement time base is input, it is input to the measurement counter A and the generation cycle T of the detection signal is measured. The data of the cycle T measured this time by the time measurement counter A is compared with the cycle T _-1 which was previously measured and stored.

Then, the ratio T / T _-1 of the current cycle T and the previous period T _-1 is greater than the predetermined value, the current period T corresponds to the time interval of the slit group 13 is outputted from the current crank angle sensor 10 When it is estimated that the detected signal corresponds to the beginning of the slit group 13, the output of the flip-flop B is raised, and
Gate C is opened. When the gate C is in the OPEN state, the detection signal (1 ° signal) from the crank angle sensor 10 is input to the 1 ° signal counter D. The count number of the 1'signal counter D advances, and the total number of slit groups 13 becomes 1.
When it comes to coincide with a predetermined value, which is the total number of detected signals, the flip-flop B which is activated at the beginning of the slit group 13
Lower the output of. Here, when the output of the flip-flop B is lowered, the gate C is closed and the detection signal from the crank angle sensor 10 is 1 ° signal counter D.
It will not be input to.

In this way, the mask circuit 17 outputs a mask pulse signal that maintains a high level only in the range of the slit group 13.

In the microcomputer 17 to which the mask signal output from the mask circuit 16 and the slit detection signal (1 ° signal) from the crank angle sensor 10 are input in this way, the ignition signal is output and ignition is performed as follows. Control.

That is, when the mask pulse signal from the mask circuit 17 rises, the ignition timing control routine preprogrammed in the microcomputer 17 is executed and the crank angle sensor
Start counting the number of 1 ° signal input from 10. Then, when the 1 ° signal count reaches a value corresponding to the ignition timing (indicating how many times before the top dead center) is set based on the engine operating state, the ignition signal is lowered.
Energization of the ignition coil constituting the ignition device 20 to which this ignition signal is input is interrupted by the fall of this ignition signal, a high voltage is generated in the ignition coil by interruption of the energization, and spark ignition by the spark plug is performed. Let it be done. Incidentally, the ignition device
20 is composed of a spark plug, an ignition coil, a power transistor, and the like.

Thus, the ignition timing is controlled by the count number of the 1 ° signal from the crank angle sensor 10,
It is possible to detect the desired ignition timing in units of 1 ° regardless of the rotation fluctuation and to perform ignition, and the crank angle sensor 10 is of a one-pickup type composed of one system of sensor and output line. Crank angle sensor 10
The configuration is simple and cost effective.

It should be noted that the ignition timing set according to the engine operating state is preset based on the maximum retard / advance value so that the 1 ° signal is included in the predetermined crank angle range output from the crank angle sensor 10. The width and position of group 13 are set based on the piston top dead center.

On the other hand, the start of energization of the ignition coil of the ignition device 20 (rising of the ignition signal) needs to be measured through the slit group 13 interval time as shown in FIG. Cannot be controlled. Therefore, as described above, the ignition signal is lowered by the 1 ° signal count (the energization to the ignition coil is cut off), and then the energization start timing (ignition signal rising timing) is controlled by the time control.

That is, the crank angle at the time when the ignition signal is lowered, the required energization time, the time from the ignition timing to the energization start timing for the next ignition are time-converted, and the ignition signal is set at the time when the set conversion time elapses after the ignition processing. By starting up, energization of the ignition coil is started in the ignition device 20 to which the ignition signal is input. Then, as described above, when the ignition timing is detected by counting the 1 ° signal from the crank angle sensor 10, the ignition signal is lowered to interrupt the energization to the ignition coil and perform the ignition. .

Here, the ignition signal from the microcomputer 18 is adapted to be output to the ignition device 20 via the monitor circuit 19 as a fail safe means, and the mask pulse from the mask circuit 17 is supplied to the monitor circuit 19. A signal and a program-run (P-RUN) signal from the microcomputer 18 are input.

The monitoring circuit 19 is configured to detect an abnormality (runaway) of the microcomputer 18 based on a program-run signal from the microcomputer 18, and when the microcomputer 18 is determined to be normal, the microcomputer 18 Ignition device directly from the ignition signal from
20 (power transistor that controls the energization of the ignition coil)
Output to. However, when the abnormality of the microcomputer 18 is detected, the output of the ignition signal from the microcomputer 18 to the ignition device 20 is prohibited, and instead, the mask pulse signal input from the mask circuit 17 is used as the ignition signal to the ignition device 20. Output.

Therefore, when the microcomputer 18 is abnormal, the energization of the ignition coil is started in synchronization with the rising edge of the mask pulse signal, and the energization of the ignition coil is interrupted in synchronization with the falling edge of the mask pulse signal to perform ignition. The crank angle sensor 10 can calculate the energization start timing and the ignition timing as 1
This is the time when the beginning and end of the crank angle range where the ° signal is output coincide.

That is, when the microcomputer 18 is abnormal,
Energization to the ignition coil is started 75 ° before, and the current is cut off 5 ° before top dead center to start ignition. Therefore, although the ignition timing cannot be variably controlled, Even if the microcomputer 18 becomes abnormal and the ignition control by the microcomputer 18 cannot be performed, the ignition can be performed at a certain time and the engine can be continuously operated.

It is obvious that the crank angle range in which the crank angle sensor 10 outputs the detection signal for each unit crank angle is not limited to BTDC5 to 75 °, and if the output range of the detection signal changes, the fail safe time The ignition timing also changes accordingly.

<Effects of the Invention> As described above, according to the ignition control device of the present invention, the one-pickup crank angle sensor is used, and even if the engine rotation suddenly changes, the ignition timing is angle-controlled to ignite at a desired timing. In addition, the ignition timing can be controlled by the mask pulse signal by masking the detection signal of the crank angle sensor and outputting the mask pulse signal output as the ignition signal even if the ignition control means becomes abnormal. Therefore, the ignition control device can be controlled, and the reliability of the ignition control device can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a schematic configuration diagram of an ignition control device showing an embodiment of the present invention, and FIG. 3 is a time showing a detection signal and an ignition signal characteristic in the same embodiment. FIG. 4 is a functional block diagram for explaining the details of the mask circuit in the above embodiment, and FIG. 5 is a time chart showing ignition control using a conventional crank angle sensor. 10 …… Crank angle sensor, 12 …… Signal disk plate, 13 …… Slit group, 14 …… Photoelectric pickup,
17 ... Mask circuit, 18 ... Microcomputer, 19 ...
… Monitoring circuit, 20… Ignition device

Claims (1)

[Claims] Claim: What is claimed is: 1. Only in a predetermined crank angle range based on the piston top dead center of the internal combustion engine, on the same output line,
A crank angle sensor that outputs a detection signal for each unit crank angle, and an ignition control unit that outputs an ignition signal to an ignition device based on the detection signal output from the crank angle sensor are provided. A mask signal output means for masking the detection signal in the predetermined crank angle range where a detection signal for each unit crank angle is output from the angle sensor and outputting a mask pulse signal, and an abnormality detection by detecting an abnormality of the ignition control means. And a fail-safe means for outputting a mask pulse signal from the mask signal output means to the ignition device as an ignition signal instead of the ignition signal from the ignition control means. Ignition control device.