JPH02140463A - Crank angle sensor for internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate the work of manufacturing and realize the drastic lowering of cost, by providing at a rotor plate signal slits opposing the same number of cylinders, and one cylinder discriminating reference signal slit on the same circumference. CONSTITUTION:Four signal slits 23-26 opposing 4 cylinders, and one cylinder discriminating reference signal slit 27 are provided on the same circumference at a rotor plate 22. Respective signal slits 23-26 are arranged circumferentially at equal intervals and also, are formed at positions within the crank angle compression upper death point of 90 degrees. The cylinder discriminating reference signal slit 27 is formed at a position within the compression upper death point of 30 degrees. Thus, the work of manufacturing becomes easy, and at the same time, the drastic lowering of cost is realized. Also, going amiss due to the wrong distribution of electricity can be surely avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an improvement of a crank angle sensor that detects the crankshaft rotational speed and each cylinder of a multi-cylinder internal combustion engine and uses it for controlling fuel supply amount and ignition timing using a computer. Regarding.

BACKGROUND OF THE INVENTION As is well known, there are various types of conventional crank angle sensors used in spark-ignition four-stroke internal combustion engines, such as a pickup type sensor using an electromagnetic pickup and a photoelectric type sensor using a photoelectric element. . Examples of the photoelectric method include JP-A-60-98171 and JP-A-60
Like the one described in Publication No. 261978, a plurality of signal slits for detecting the crank angle position are formed on the outer circumferential side of a rotor plate that is built into the distributor and rotates in synchronization with the crankshaft, while each signal slit is formed on the inner circumferential side. A signal slit for cylinder discrimination is formed, and two signals are picked up from each signal slit and output to a microcomputer. The microcomputer is
Based on these signals, etc., ignition timing control, fuel injection amount control, etc. are mainly performed using fixed ignition timing or variable ignition timing.

Problems to be Solved by the Invention However, in the above-mentioned conventional crank angle sensor, multiple internal and external signal slits are formed on the rotor plate, and in particular, the slit for detecting the crank angle position is formed minutely, so manufacturing is complicated. And the manufacturing work becomes complicated,
Therefore, an increase in costs is inevitable.

In addition, especially in the latter conventional example, since the cylinder identification slit is formed at a position unrelated to the compression top dead center position of the crankshaft, for example, when starting the engine, etc.
If the cylinder cannot be discriminated, ignition is performed not only by the crank angle position signal but also by the cylinder discrimination signal, so there is a risk that incorrect power distribution to the ignition coil may cause ignition, for example, during the intake stroke.

Means for Solving the Problems The present invention has been devised in view of the above-mentioned conventional problems. For example, the present invention is based on the configuration of a photoelectric crank angle sensor, and in particular, a signal slit corresponding to the number of cylinders is installed on the rotor plate. and one cylinder discrimination reference signal slit are provided on the same circumference, and each of the signal slits is arranged at equal intervals in the circumferential direction and is formed at a position within 90 degrees before the top dead center of crank recompression. It is characterized in that the cylinder discrimination reference signal slit is formed at a position within 30 degrees after compression top dead center.

Effects According to the present invention having the above configuration, all nine slits provided in the rotor plate are provided on the same circumference, and the total number of slits is only one more than the number of cylinders, so the rotor plate can be simplified and Manufacturing work efficiency is improved. Moreover, because each slit is arranged in a unique manner as described above, even if it is not possible to distinguish between cylinders at the time of starting, for example, the ignition timing can be set before the compression top dead center of the first cylinder, and then the cylinder discrimination standard can be set. Further compression after top dead center by pulse signal 3
Controlled to ignite within 0°. Therefore, ignition during the intake stroke due to incorrect power distribution is reliably prevented.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 shows the mechanical configuration of a 4-cycle, 4-cylinder, electronically controlled internal combustion engine I to which the present invention is applied, and 2 is a CPU 3. ROM4. The microcomputer 2 is a controller equipped with a RAM 5° 110 port 6, and the microcomputer 2 receives the intake air amount signal Qa from the air flow meter 8 of the intake pipe 7 and the opening amount from the opening detection sensor IO of the throttle valve 9. In addition to the signal TVO and the cooling water temperature signal T from the water temperature sensor 11, O provided in the exhaust pipe 12, the reference voltage ■ from the sensor 13, and the photoelectric crank angle sensor 2I built into the distributor 14. The current engine operating state is detected by manually inputting the engine speed signal N, etc., and the optimum ignition timing control is performed and the signal is output to the spark plug 15. On the other hand, the injection fuel electric current is controlled and the signal is output to the spark plug 15. is output to the fuel injection valve 16.

The crank angle sensor 21 is connected to the rotor brake 1 connected to the disshaft 17 as shown in FIG.
22, a light emitting diode and a light receiving diode (not shown) set above and below the rotor plate 22, and a signal processing section.
#2. #3. Four signal slits 23, 24, 25, 26 corresponding to the #4 cylinder and one cylinder discrimination reference signal slit 27 are provided on the same circumference.

The four signal slits 23, 24, 25° 26 are set to have the same length in the circumferential direction, and are arranged at symmetrical positions with respect to the disshaft 17, that is, at equal intervals of 180°. In addition, each signal slit 23,
24, 25, and 26, the pulse signal is approximately 7 points before the compression top dead center (TDC) of the crank rotation angle, as shown in Fig. 2 a.
The width from the H level edge to the L level edge is set so that it rises at around 5° and falls at around 5° before TDC. On the other hand, the cylinder discrimination reference signal slit 27 has a length in the circumferential direction of each signal slit 23, 2.
4, 25. Set shorter than the length of 26, near the #l cylinder signal slit 23, that is, about 30 degrees after the above TDC.
The H level edge (OH) is set at a position of about 5° after TDC.

And each of the above slits 23, 24, 25, 26, 27
As a result of the light passing through the cylinder, an ON-OFF pulse signal including a rank angle 180° signal and a cylinder discrimination reference signal is output as shown in FIG. 2a.

The microcomputer 2 inputting each of these pulse signals measures the time between the 180° crank angle signals to detect the engine rotation speed N, and combines this engine rotation speed N with the intake air amount signal Qa from the air flow meter 8. Variable ignition timing control is performed using ignition timing value data calculated from a function of Fixed ignition timing control is performed according to the number N (see Figure 2). The H level width of the 180° pulse signal is set to 70'' and the L level width is set to 110', the energization time in the fixed ignition timing control is the same as during the 180° pulse, and the ignition timing is L. On the other hand, the energization time in variable ignition timing control is calculated by calculating the energization time stored in the microcomputer 2 into the energization angle, and the ignition timing is based on the H level of the 180° signal. The advance timing is set at a predetermined angle.

In addition, the microengine computer 2 performs fuel injection control depending on the engine operating state, for example, at the time of engine startup (based on the crank angle position detection signal), and performs simultaneous injection in all cylinders based on the crank angle position detection signal. So-called sequential injection is performed in which fuel is injected in order before the compression-F dead center of each cylinder based on the angular position detection signal and the cylinder discrimination signal.

Hereinafter, the control action of the microcomputer 2 will be explained based on the flowchart of FIG. 4.

This basic routine is interrupted at the rise or fall of the pulse signal output from the crank angle sensor 21.

First, in section 1, between each pulse (Fig. 2 DT, ~D
Read the time of time ratio (D n) in section 2
DT) is calculated using the formula DTn-1/DTn. Next, in section 3, after turning the start switch ON, it is determined whether the input pulse is equal to or greater than a predetermined number of times. Here, if it is No. 1, that is, if the crankshaft rotates less than 2 times and generates less than 5 pulses, no determination is made and the process proceeds to section 4. Here, fuel injection is performed once every two times of the H level signal, ignition is energized with the H level signal, and a control flag (FLG) for discharging is set at the L level, and the process proceeds to a routine (FLGAO) to be described later. On the other hand, if YES in section 3, it is determined in section 5 whether the pulse signal is at H level or not, and if it is not at H level, the process proceeds to the next routine by interrupting with a rising edge. If it is determined in section 5 that the signal is at the H level, the process proceeds to section 6, where it is determined whether the time ratio calculated in section 2 is greater than or equal to a predetermined value. That is, here, it is determined whether the ratio θ, /θ, (see FIG. 2) of the current L level angle θ of the pulse signal to the previous 11th level angle θ (see FIG. 2) is larger than, for example, 3. The reason why the value is set to 13 or more is to set the value within a range where the resolution of the pulse width can be exhibited and where a fixed advance angle range (5° to 10°) of the ignition timing can be obtained. Here, if it is determined that it is 3 or more (
If the cylinder discrimination reference signal is 011 (which occurs once every five times), the cylinder recognition signal F L G B is set to 1 in section 7 to simply recognize the cylinder. Next, in section 8, the measurement time T 1110 and the number of rotations N between 180° angles, which will be described later, are calculated. Next, in section 9, it is determined whether or not the starting switch is OFF, and if it is OFF, in section 10, it is determined whether the engine rotation speed N is, for example, 40 Qr-pm or more, and 400 r-p-m or more. Then F in section 11
It is determined whether LGC is 1 or not. In other words, here, it is determined whether all the conditions such as the above-mentioned start switch and engine speed satisfy the conditions for enabling sequential control, and if YES, a flag is flagged in section 12 to carry out sequential injection 1-flame advance. is set and the process moves to a routine (FLGA=2) described later.

On the other hand, if any one of Sections 9, 10, and 11 above is NO, proceed to Section 13, where a flag is set to perform two simultaneous fuel injections per crankshaft revolution and one ignition timing with a fixed conduction angle. The routine described below (FLGA
=1).

On the other hand, if the determination is No in section 6 (other than the case where the cylinder determination reference signal is OH), then in section 14
It is determined whether LGB is set to 1, that is, it is determined whether the cylinder recognition signal is on, and if YES, the M cylinder (CYL) is set to O in section 15 to set a reference. Here, MCYL is a variable that uses 0, 1.2.3, and when it is 0, it is the first cylinder, and when it is 1, it is the second cylinder.When FLGB=1 above, MCYL is set to 0. There is. Next, in section I6, set FLGC to 1
, and in section 17 set the engine speed N as described above.
The element to find is the time T +e for 180°. of '
Measured by EDT.

That is, here, since MCYL=0 in section 15, the four times of DT, +DTi+DT, and +-DTs are added and measured. Next, section 18
In this case, the time DTB between L levels (110'') which is the reference for ignition timing is measured, and in this case, since there is a cylinder discrimination reference signal 27, this signal is included.
Measured by DT. In other words, DT3+DT, +D
It is measured by adding up the three times Ts.

Subsequently, in section 19, the time DT between 110'' mentioned above is
B is sequentially updated and new reference values are measured and stored. This is what is used to calculate the angular acceleration bone. Next, in section 20, FLGB is set to O. In other words, F
When LGB is 0, it is a state where the cylinder discrimination reference signal 27 is not set, and at this time MCYL = o in section 15, so next time it will be 0 + 1 for the first cylinder, then the second cylinder. ... is recognized, and the process moves to the above section 8, whereupon the above-mentioned judgments and processes are performed.

If FLGB is not set to 1 in section 14, the cylinder identification signal 27 is not output, so section 21 adds MCYL one cylinder at a time, and then section 22 adds 'XDT, Measure the time of 180° using the formula. Then in section 23 1
A time DTB of 10° is measured from DTn, and the process moves to the above-mentioned section 19 to perform subsequent processing.

Hereinafter, the above FLGA=O, FLGA=1. FLGA=
The second routine will be explained. First, the routine for FLGA=O from section 4 where cylinder identification is not possible is as follows.
As shown in FIG. 5, section 30 again determines whether the pulse signal is at the "■" level, and if YES, energizes the ignition primary coil at about 75 degrees before compression top dead center in section 31, and At step 32, it is determined whether fuel injection was performed based on the previous pulse H level signal, and Y
If it is ES, it will return without any processing. If the determination in section 32 is NO, then in section 33 simultaneous injection is performed in all cylinders at a rate of once every two H level signals. Further, if the section 30 determines that the pulse signal is at the L level, the section 34 cuts off the current to the ignition primary coil. That is, it ignites at about 5 degrees before compression top dead center and returns. Note that in a state where such cylinder discrimination is not performed, the cylinder discrimination reference signal is generated at 5 degrees after the compression top dead center, and is fired immediately after the compression stroke, in addition to the above-mentioned crank angle position signal. ignition, there is no effect on the engine cycle, and on the contrary, a good combustion effect can be obtained.

Next, in the routine <FLGΔ=1 following section 13, since cylinder identification has already been performed and the engine is under operating conditions such as starting, the control is as shown in FIG. 6.

First, in section 40 it is determined whether or not the pulse signal is at H level, and if it is at H level, it is determined in section 41 whether or not the time ratio is greater than a predetermined value, that is, "3" or more.

If it is determined that it is 3 or more, a cylinder identification flag is set in section 42 and the process returns directly. Also, if it is determined NO in section 40, that is, the L level, the process proceeds to section 43, where it is determined whether the cylinder identification flag is set, and if it is set, the process returns, but if it is not set, it is determined that the cylinder identification flag is set. In section 44, the current to the ignition primary coil is cut off and ignition is started based on the fixed ignition timing control. On the other hand, section 41
When it is determined that the time ratio is "3" or less, that is, when the pulse signal other than the cylinder discrimination reference signal reaches the H level, the primary fill is energized in section 45, and then in section 46, the pulse signal is energized at the previous H level. Determine whether or not it was injected. If YES here, proceed to section 48 and NO
If so, in section 47 simultaneous injection is performed in all cylinders twice per crankshaft revolution, and the process proceeds to section 48. In this section 48, processing is performed to lower the cylinder identification flag, and the process returns directly.

Next, the routine (continued from section 12 <FLGA=217) determines whether the pulse signal is at the H level in section 50 as shown in FIG. 7, and if NO, returns as is, but if YES In section 51, it is determined whether the time ratio is "3" or more. If YES here, the signal is cleared, but if NO, in section 52, ignition and energization are performed by variable ignition timing control in each cylinder corresponding to MCYL based on sequential control, and fuel injection is performed for each cylinder. , returns as is.

Incidentally, in the above embodiment, an application is shown to a four-cylinder engine, but the present invention is not limited thereto, and is not limited to a photoelectric type.

Effects of the Invention As is clear from the above explanation, according to the crank angle sensor for an internal combustion engine according to the present invention, the signal slit corresponding to the number of cylinders and one cylinder discrimination reference signal slit are arranged on the same circumference of the rotor plate. Since it is provided on the top, the structure of the rotor plate is simplified, and therefore the structure of the entire crank angle sensor including the signal big absorb mechanism is simplified. As a result, manufacturing operations become easier and costs can be significantly reduced.

In addition, each signal slit is formed within 90 degrees before the crank angle top dead center, while the cylinder discrimination reference signal slit is formed within 30 degrees after the top dead center. Even if ignition occurs based on the cylinder discrimination signal in addition to the crank angle position signal, the ignition will always occur before and immediately after compression top dead center. Therefore, problems caused by incorrect power distribution as in the prior art are reliably avoided.

Furthermore, the cylinder discrimination reference signal 71- enables ignition within one revolution of the crankshaft, improving startability.

[Brief explanation of the drawing]

Fig. 1 is an enlarged view of essential parts showing an embodiment of the crank angle sensor according to the present invention, Fig. 2 is a characteristic diagram of a pulse signal in this embodiment, and Fig. 3 is an illustration of an internal combustion engine to which this embodiment is applied. FIG. 4 is a flowchart showing basic control of the microcomputer used in this embodiment; FIG. 5 is a flowchart of FLGA-0 shown in FIG. 4; FIG. FIG. 4 is a flowchart of FLGA=1 shown in FIG. 4, and FIG. 7 is a flowchart of FLGA=2 shown in FIG. 17...Disshaft (rotating shaft), 21...Crank angle sensor, 22...Rotor plate, 23-26...
... Signal slit, 27... Cylinder discrimination reference signal slit. Figure Figure Figure Figure Figure

Claims (1)

[Claims] (1) A crank angle sensor in which a plurality of slits are formed in the circumferential direction of a rotor plate that rotates synchronously with the crankshaft, and picks up the slits and outputs various information signals to a controller, and the rotor plate has cylinders Signal slits corresponding to the number of signal slits and one cylinder discrimination reference signal slit are provided on the same circumference, and each of the signal slits is arranged at equal intervals in the circumferential direction and is located within 90 degrees before the top dead center of crank angle compression. A crank angle sensor for an internal combustion engine, characterized in that the cylinder discrimination reference signal slit is formed at a position within 30 degrees after compression top dead center.