JPH0517426Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This idea detects the signal output from a magnetic signal generator, which consists of a signal rotor and a corresponding magnetic pickup, which is installed in, for example, an automobile distributor. The present invention relates to a signal detection circuit for an internal combustion engine.

[Conventional technology]

FIG. 5 shows an example of a magnetic signal generator that alternately generates positive waves and negative waves. In the figure, 1 is the housing of the distributor, 2 is a rotating shaft rotated in synchronization with the rotation of the internal combustion engine, 3 is a signal rotor fixed to the rotating shaft 2, and 4 is a housing 1 facing the signal rotor 3. It is a magnetic pick-up fixed to the. Magnetic pick-up 4 is magnet 5
It consists of a magnetic core 6 and a pickup coil 7 wound around the core 6. The signal rotor 3 is made of a magnetic material and has a protrusion. Therefore, when the rotating shaft 2 rotates and the protrusion of the signal rotor 3 approaches the magnetic pickup 4, a negative (or positive) voltage is generated between both ends of the pickup coil 7, and the protrusion approaches the magnetic pickup 4. When the pickup coil 7 is separated from the pickup coil 7, a positive (or negative) voltage is generated across the pickup coil 7.

Conventionally, these voltages have been detected by a detection circuit as shown in FIG. That is, 7 is a pick-up coil, 8 is a diode connected to one end of the pick-up coil 7 in the positive direction, 9 is a diode connected to one end of the pick-up coil 7 in the reverse direction, and 10 is a capacitor connected in parallel to this. 10' is a bias circuit consisting of a resistor and connected to diode 9; 10' is a bias circuit consisting of a capacitor and a resistor connected in parallel to the diode 8;
11 is a resistor whose one end is connected to the bias circuit 10' and the other end is grounded; 12 is a resistor whose one end is connected to the bias circuit 10 and the other end is connected to a constant voltage source; 13; is a diode with one end connected to the bias circuit 10 and the other end grounded in the direction shown; 14 has its base connected to the bias circuit 10', its emitter grounded, and its collector connected to a constant voltage source via a resistor 16; A transistor 15 has its base connected to the bias circuit 10, its emitter is grounded, and its collector is connected to a constant voltage source via the resistor 17. A transistor 18 has its base connected to the collector of the transistor 14, and its emitter is grounded. A is a transistor whose collector is connected to a constant voltage source through a resistor 19, and A is a transistor 1 which is grounded.
5 is an output terminal drawn out from the collector of transistor 18, and B is an output terminal drawn out from the collector of transistor 18. The other end of the pick-up coil 7 is grounded.

The conventional detection circuit is configured as described above, and the fourth
As shown in the figure, when a negative wave a arrives at one end of the pickup coil 7, the detection circuit outputs a rectangular wave at its output end A.
A′ is output, and when positive wave b comes, a square wave is output to output terminal B.
Give b′. Diodes 8 and 9 distinguish between negative wave a and positive wave b generated at one end of pickup coil 7. When the negative wave a occurs, the current that has been flowing from the constant voltage source, through the resistor 12, through the base of the transistor 15, and from the emitter to the ground is pulled toward the diode 9. Thus, the current that had been flowing from the constant voltage source through the resistor 17, from the collector of the transistor 15 to the emitter, and then to the ground, no longer flows, and the current flows from the constant voltage source to the resistor 17.
Current will flow to the output terminal A through. Therefore, a rectangular wave a' as shown in FIG. 4 is outputted to the output terminal A.

During positive wave b, current flows through diode 8 from the base of transistor 14 to the emitter and to ground. As a result, a current flows from the constant voltage source through the resistor 16 from the collector to the emitter of the transistor 14 and is grounded. As a result, the current that has been flowing from the constant voltage source through the resistor 16, from the base of the transistor 18 to the emitter, and to the ground is eliminated. Thus, a current flows from the constant voltage source through the resistor 19 to the output terminal B. Therefore, a rectangular wave b' is outputted to the output terminal B as shown in FIG. In this way, positive wave b
, the positive wave triggers transistor 18 after being inverted by transistor 14 .

The bias circuits 10 and 10', which are constructed of parallel circuits of resistors and capacitors, function well in high frequency ranges (during high-speed rotation of the internal combustion engine) to increase noise resistance.

[Problem that the invention attempts to solve]

For example, in the case of a two-wheeled vehicle, the wave heights of the positive and negative waves output from the pick-up coil 7 are approximately equal to
At 100 rpm, it is approximately 1.2V. In the case of a negative wave, the voltage drop V _F of about 0.6 V due to diode 9 is canceled out by the voltage drop V _BE between the base and emitter of transistor 15, and when a slight negative voltage occurs, transistor 1
5 can be sufficiently triggered. but,
In the case of positive wave b, there is a voltage drop between the base and emitter of transistor 14 (V _BE : approximately 0.6V) in addition to the voltage drop due to diode 8 (V _F : approximately 0.6V), so positive wave b is approximately The transistor 18 cannot be triggered unless the voltage is 1.2V or higher. When the rotational speed is low, such as when starting the internal combustion engine, the heights of the positive waves and negative waves generated in the pickup coil 7 become low. Therefore, with such a conventional detection circuit, it is difficult to detect a positive wave at the time of starting. For this reason, there has been a problem in that internal combustion engines subject to electronic advance angle control have poor startability.

This invention was made in order to solve this problem, and the purpose is to obtain a detection circuit in which the trigger level, which was previously high for positive waves, is reduced to the same level as for negative waves. .

[Means for solving problems]

The detection circuit according to this invention has a circuit for detecting a negative wave connected to each end of a pickup coil, and a first diode for grounding a positive wave to each end of the pickup coil.

[Effect]

In this invention, we take advantage of the property that the positive waves and negative waves generated at both ends of the pickup coil are symmetrical with each other, and connect a detection circuit to each end of the pickup coil, so that each detection circuit detects the negative wave. Since both are designed to respond, signals can be detected even when the trigger level is low.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of this invention, and FIG. 2 is an operating waveform diagram thereof. 7,9,1
0, 12, 13, 15 and 17 correspond to components of a conventional detection circuit. The circuit from one end of the pickup coil 7 to the output end A and the circuit from the other end of the pickup coil 7 to the output end B are completely the same. A first diode 21 is connected to one end of the pickup coil 7 in the direction shown, and the other end of this diode 21 is grounded. A bias circuit 10 is connected to one end of the pickup coil 7, and a second diode 9 is connected to the other end of the bias circuit 10 in the direction shown. A resistor 12 is connected to the other end of this diode 9, and the other end of the resistor 12 is connected to a constant voltage source. Further, a fourth diode 13 is connected to the other end of the diode 9 in the direction shown in the figure, and the other end of the diode 13 is grounded. Furthermore, a third diode 20 is connected to the other end of the diode 9 in the direction shown. The base of the transistor 15 is connected to the other end of the diode 20. The emitter of this transistor 15 is grounded, and the collector is connected to a constant voltage source via a resistor 17. Further, an output terminal A is drawn out from the collector of the transistor 15. At the other end of the pickup coil 7, the same circuit as described above is arranged up to the output end B.

In the detection circuit configured as above,
As understood from FIG. 2, the positive waves and negative waves generated at each end of the pickup coil 7 are opposite to each other. Now, when the negative wave a comes to the end, the positive wave at the end is grounded through the diode 21 on the end side, and the voltage drop due to the diode 21
Clipped by V _F. Based on this, there is a wave height of the negative wave a at the end. This negative wave a transfers the current that had previously flowed from the constant voltage source through the resistor 12 and further from the diode 20 to the base and emitter of the transistor 15 to the ground.
Pull it towards. In this way, the current flowing from the constant voltage source through the resistor 17 and further from the collector and emitter of the transistor 15 to the ground is directed to the output terminal A. Thus, a rectangular wave a' is outputted to the output terminal A as shown in FIG.

When a positive wave comes to the end, it is grounded through the diode 21 on the end side and is clipped by the voltage drop V _F caused by the diode 21. Based on this, there is a negative wave height at the edge. This negative wave b causes the output end B to output a rectangular wave b' in the same manner as described above.

Diode 21 grounds the positive wave entering the circuit, and diode 9 blocks the passage of the positive wave entering the circuit. The diode 13 makes the bias circuit 10 work effectively, so when a negative wave is generated at the end, the capacitor of the bias circuit 10 is
It quickly accumulates electric charge. diode 20
is arranged to compensate for the voltage drop caused by providing the first diode 21.

Note that although NPN type transistors are used in the above embodiments, it is obvious that a PNP type transistor can be similarly configured. In this case, a positive wave is detected.

Incidentally, in the above explanation, this invention was described in relation to a magnetic signal generator for a distributor, but it is widely used to detect signals from a signal generator that alternately generates positive waves and negative waves. It goes without saying that it can be done.

[Effect of idea]

As explained above, this idea utilizes the symmetry of the positive waves and negative waves generated at each end of the pick-up coil to detect only waves of the same polarity at each end of the pick-up coil (for example, the conventional negative (similar to the wave detection section) are connected independently, so the inverting circuit, for example 14,
The increase in the trigger level due to the presence of 16 is eliminated, and a high sensitivity is obtained, which has the effect of improving the startability of an internal combustion engine using electronic advance angle control.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of this invention, Figure 2 is a diagram showing operating waveforms of this invention, Figure 3 is a diagram showing a conventional signal detection circuit for internal combustion engines, and Figure 4 is its operation. FIG. 5, a diagram showing waveforms, is a diagram showing an example of a magnetic signal generator that alternately generates positive waves and negative waves. In the figure, 7 is a magnetic signal generator, 21 is a diode, 10 is a parallel circuit of a capacitor and a resistor, 9 is a diode connected to the other end of the parallel circuit 10, 15 is a transistor, 13 is a diode, and 12 is a resistor. , 20 are diodes.
Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] A signal detection circuit that detects each wave generated by a magnetic signal generator that alternately generates positive waves and negative waves and generates an output signal, the signal detection circuit comprising a pickup coil for generating the signal. Connect a negative wave detection circuit to each end of the
In a signal detection circuit for an internal combustion engine configured to ground waves of other polarity, a first diode is connected between the input terminal and the ground, and a parallel circuit of a capacitor and a resistor is further connected to the input terminal, At the other end of this parallel circuit, a second
A third diode, a fourth diode, and a resistor are connected to the other end of this diode, the other end of this resistor is connected to a constant voltage source, and a transistor is connected to the other end of the third diode. , the other end of the fourth diode is grounded, the emitter of the transistor is grounded, the collector of the transistor is connected to a constant voltage source via a resistor, and the output end is connected to the collector of the transistor. . A signal detection circuit for an internal combustion engine, characterized in that the circuit from the input end to the output end is connected to each end of a signal generator.