JPH0681916B2 - Crank angle detector for internal combustion engine - Google Patents

Description

The present invention relates to a crank angle detecting device for an internal combustion engine.

<Prior Art> Conventionally, a crank angle detection device has been used for various controls of an internal combustion engine, for example, ignition control.

There are various types of systems for performing ignition control using a crank angle detection device, but recently, at a predetermined crank angle position (a predetermined reference position of a piston) in a specific stroke of each cylinder in synchronization with engine rotation. There is an increasing number of methods of controlling the ignition time by a micro computer using a crank angle detector having only the function of outputting a reference pulse signal (see Japanese Patent Application No. 62-133304, etc.).

That is, for example, as shown in FIG. 4, the synchronization 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.

Such a system does not require the crank angle detecting device to have a unit signal generating function for each crank angle of 1 to 2 ° in addition to the reference signal, and the ignition timing can be controlled as one pickup system so that the cost can be reduced. Because it is advantageous.

<Problems to be Solved by the Invention> However, when electronic distribution is performed without using a distributor, or when not only ignition control but also a cylinder-by-cylinder fuel injection system is adopted, not only the reference pulse signal , It is necessary to obtain a signal for discriminating the cylinder.
There was a problem that it became a system and there was a limit to cost reduction.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a crank angle detection device for an internal combustion engine, which is capable of cylinder discrimination while adopting the one-pickup method.

<Means for Solving the Problems> Therefore, in the crank angle detecting device according to the present invention, detection is made for each unit crank angle on the same output line only in a predetermined crank angle range based on the piston predetermined reference position of the internal combustion engine. In addition to outputting a signal, at the piston predetermined reference position of the specific cylinder, in addition to the predetermined crank angle range, further output a detection signal on the same output line, the detection signal of the piston predetermined reference position of the specific cylinder It was configured to increase the number of occurrences.

<Operation> In such a configuration, in the cylinders other than the specific cylinder, the detection signal is output on the same output line for each unit crank angle within a predetermined crank angle range based on the piston predetermined reference position. In addition to the crank angle range, further detection signals are output on the same output line, so that a specific cylinder is determined based on the generation of detection signals outside the predetermined crank angle range, in other words, the number of detection signals generated. It becomes possible.

Further, for example, when the piston predetermined reference position is set as the piston top dead center (compression top dead center) and the predetermined crank angle range is made to correspond to the ignition timing change range, a unit output in the predetermined crank angle range The ignition timing can be variably controlled based on the detection signal for each crank angle, and the fuel injection control for each cylinder can be similarly performed.

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

FIG. 1 shows a crank angle detecting device 10 according to the present invention, in which a signal disk plate 12 is attached to a rotating shaft (for example, a distributor shaft or a cam shaft) 11 which rotates 1/2 times per one rotation of the signal disk plate. A slit group 13 of several cylinders (four cylinders in this embodiment is four) is formed at 12 at equal intervals in the circumferential direction. Then, the projector (LED) 1 that constitutes the photoelectric pickup 14 with the signal disk plate 12 sandwiched therebetween.
5 and a photodetector (photodiode) 16 are provided, and a slit group 1
A detection signal is output based on a light reception signal when the light from the light projector 15 passes through the plurality of slits forming part 3.

Here, as shown in FIG. 2, the slit group 13 includes a crank angle range from 75 ° before top dead center to 5 ° before top dead center (the compression upper limit of each cylinder) as the piston predetermined reference position of each cylinder. In the range of the crank angle before dead point 70 °, which corresponds to the required ignition timing control range), slits corresponding to a unit angle of the crank angle of 1 ° are also provided at intervals of 1 °. The detection signal by the light passing through the slit (slit detection signal) is a pulse signal in which rising and falling are alternately repeated at every crank angle of 1 °.

Such a slit group 13 is provided before the compression top dead center of each cylinder, but in the present embodiment, after the slit group 13 before the compression top dead center of the # 1 cylinder, a cylinder corresponding to a crank angle of 1 ° width is also provided. A slit 17 for discriminating is provided so that the number of detection signals output from the photoelectric pickup 14 before the top dead center of the # 1 cylinder is larger than that of other cylinders by the slit 17 for discriminating the cylinder. There is. The fall of the detection signal of the cylinder discrimination slit 17 coincides with the compression top dead center of the # 1 cylinder. Further, in the present embodiment, the cylinder discriminating slit 17 has the same width as the slit width of the slit group 13, but it does not necessarily have to be the same.

The signal from the crank angle detector 10 is supplied to the mask circuit 18
On the other hand, the mask circuit 18 is input to the CLK terminal of the microcomputer 19, and the mask circuit 18 masks the detection signal from the crank angle detection device 10 to obtain a mask signal to the microcomputer 19 for edge sensing IRQ (mask signal Output to the pin that executes the interrupt routine synchronized with the fall).

The mask circuit 18 outputs a mask signal in which the start of the slit group 13 rises and the end of the slit group 13 falls. That is, the mask circuit 18 compares the generation interval time Tb of the pulse signal corresponding to the 1 ° width of the crank angle output from the crank angle detecting device 10 with the pulse width Ta of the pulse signal corresponding to the 1 ° width. Also when Tb is sufficiently large, it is determined that it is the first pulse signal of the slit group 13, and the mask signal is raised in synchronization with the rise of the pulse signal output from the crank angle detection device 10 this time. After that, the High state is maintained until the slit group 13 ends, and when the count of the number of pulses detects that the crankshaft has rotated by 70 °, it is considered that the slit group 13 has ended and the pulse is lowered.

In this way, the microcomputer 19 to which the mask signal output from the mask circuit 18 and the slit detection signal from the crank angle detection device 10 are input performs cylinder discrimination as shown in the flowchart of FIG.

The cylinder discrimination routine shown in FIG. 3 is executed when the falling edge of the mask signal from the mask circuit 18 is detected (interrupt processing).
To be done.

In step 1 (indicated as S1 in the figure, and so on)
After the falling edge of the mask signal, 1 ° from the crank angle detector 10
It is determined whether or not a width pulse signal (slit detection signal) is output. Since the mask signal is output for each slit group 13, the pulse signal output from the crank angle detecting device 10 after the falling of the mask signal until the rising thereof is only the cylinder discrimination slit 17. Therefore, when the input of the slit detection signal is detected in step 1,
The detection signal is the detection signal of the cylinder discrimination slit 17, and the fall of the cylinder discrimination slit 17 indicates the compression top dead center of the # 1 cylinder. Specifies that it was before the compression top dead center of the # 1 cylinder.

Then, in the next step 3, the cylinder counter is set to # 1 so that the # 1 cylinder is determined.

On the other hand, if it is determined in step 1 that the slit detection signal is not output from the crank angle detection device 10 after the mask signal falls, the process proceeds to step 4 and step 3
The counter set to # 1 is incremented by 1. Therefore, in the case of the four-cylinder engine in the present embodiment, the counter changes in the order of 1 → 2 → 3 → 4 → 1, and the slit group 13 is located before the compression top dead center of the cylinder depending on the value of this counter. It is possible to specify whether or not it is equivalent.

In the cylinder discrimination based on the signal from the crank angle detecting device 10 as described above, the ignition control can be performed as follows, for example.

That is, since the rising edge of the mask signal output from the mask circuit 18 is at a position of 75 ° before the compression top dead center, a desired ignition timing is set every 1 ° from the crank angle detecting device 10 with reference to this crank angle position. The output pulse signal is detected by counting, and when the counted number corresponds to a desired ignition timing, the energization to the ignition coil is cut off to ignite. On the other hand, the start timing of energization to the ignition coil is detected by measuring the crank angle from the time of de-energization to the crank angle position at which the energization is to be started next, and measuring it from the time of de-energization. To start. The energization start timing is controlled by time because the non-energization timing overlaps the interval of the slit group 13. Further, fuel injection control for each cylinder may be performed in the same manner as the above ignition control.

As described above, according to the crank angle detecting device 10 of this embodiment, the slit group is formed by one system of the photoelectric pickup 14.
13 and the cylinder discriminating slit 17 are detected, and the cylinder discriminating unit can easily perform the cylinder discriminating by the one detection signal system, and the slit group 13 corresponds to the required ignition timing change range. Therefore, the ignition timing of each cylinder can be angle-controlled based on the slit detection signal based on the cylinder discrimination result.

In this embodiment, as shown in FIG. 2, the top dead center of each cylinder is set as a piston predetermined reference position, and a detection signal for each unit crank angle is output within a predetermined crank angle range before such compression top dead center. However, the piston predetermined reference position is not limited to top dead center, and the crank angle range for outputting a detection signal for each unit crank angle is BTDC5 to 75 ° even if the reference is top dead center. Obviously, it is not limiting.

<Effects of the Invention> As described above, according to the crank angle detecting device of the present invention, the detection signal for each unit crank angle is output on the same output line only in the predetermined crank angle range based on the piston predetermined reference position. In addition to outputting the detection signal on the same output line in addition to the predetermined crank angle range at the piston predetermined reference position of the specific cylinder, the number of detection signals generated only at the piston predetermined reference position of the specific cylinder. Therefore, the cylinder discrimination and the crank angle control can be performed with a simple configuration of the one-pickup system, and the cost of the crank angle detection device can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a crank angle detecting device and a signal processing circuit showing an embodiment of the present invention, FIG. 2 is a time chart showing detection signal characteristics in the same embodiment, and FIG. 3 is cylinder discrimination in the same embodiment. FIG. 4 is a flowchart showing a routine, and FIG. 4 is a flowchart showing ignition timing control using a conventional crank angle detecting device. 10 ... Crank angle detection device, 12 ... Signal disk plate, 13 ... Slit group, 14 ... Photoelectric pickup, 17 ... Cylinder discrimination slit, 18 ... Mask circuit, 19 ... Microcomputer

Claims (1)

[Claims] 1. A detection signal for each unit crank angle is output on the same output line only within a predetermined crank angle range with reference to a piston predetermined reference position of an internal combustion engine, and a piston predetermined reference of a specific cylinder is provided. The internal combustion engine is characterized in that, in the position, in addition to the predetermined crank angle range, a detection signal is further output on the same output line, and the number of detection signals generated increases only at the piston predetermined reference position of the specific cylinder. Crank angle detector.