JPS6123866A - Contactless ignitor for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the ignition performance on starting by generating the electric discharge of main condensers by alternately putting two semiconductor opening/closing elements into electric conduction at each revolution of an engine. CONSTITUTION:The first and the second main condensers 9 and 10 are charged by a power generation coil 1, and other edges are connected to an ignition coil 19. The first and the second thyristors 11 and 12 control the electric discharge of the electric charges charging the main condensers 9 and 10. A signal output circuit 18 receives the signal of a revolution sensor 2 and outputs the gate trigger signals of two thyristors 11 and 12. Therefore, the electric discharge of one of the main condensers 9 and 10 forms regular spark and the electric charge in the case when the revolution after compression cycle is high can be used as the charge for regular spark, and the ignition performance on starting can be improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a capacitive discharge non-contact ignition device for an internal combustion engine using a magnet generator, and in particular to a device with excellent ignition performance during starting. It provides:

(Prior art) When an engine is started, the rotational speed of the magnet generator directly connected to it is low, so sufficient charging voltage cannot be obtained for the ignition capacitor, and therefore the secondary coil of the ignition coil for,
Sufficient secondary voltage cannot be obtained to ignite the mixture. In particular, when starting a four-stroke, single-cylinder engine with a relatively large displacement, the effect is significant, and the engine may start poorly. Figure 3 shows an example of this, where N is the instantaneous rotational speed of the engine, Vs is the signal voltage, and Vc is the charging voltage of the ignition main capacitor. Figure 3 shows the state at the time of starting the starter. . When the starter starts, the rotational speed of the engine rapidly decreases during the compression process, and after the compression process is exceeded, the rotational speed rapidly increases due to the expansion of the compressed air-fuel mixture. Then, during the exhaust process when the exhaust valve is open, there is no compression or expansion of the air-fuel mixture, so the rotation is almost constant, and then the rotation speed drops rapidly during the compression process, and this is repeated thereafter.

Here, looking at the charging voltage VC of the main capacitor for ignition, after the compression process is exceeded, the rotation speed becomes high.

However, this charged charge is discharged during the exhaust process and becomes a wasted flame, and the spark that is actually used as a regular spark is
This is by charging after the exhaust process. However, the rotational speed after the exhaust process is not that high, so in the end V in Figure 3
As shown in the c waveform, the charging voltage in the exhaust process, which is wasteful combustion, is high, and the charging voltage in the important compression process becomes low, resulting in a problem that the air-fuel mixture may not be ignited.

This problem also occurs in a device in which the charges of two main capacitors are discharged to the primary coil of the same ignition coil, as described in Japanese Patent Application Laid-Open No. 47-15522.

As a countermeasure for this, there are methods such as increasing the number of turns of the generator coil or increasing the size of the magnet, but in the former case,
The increase in inductance causes the charging voltage to drop at high speeds, and in the latter case there is a problem in that the heat generation of the generator coil increases, and in the end, performance has to be compromised to a certain extent.

(Problems to be Solved by the Invention) The present invention uses charging at high revolutions after the compression stroke as the charging voltage for the regular spark, and without changing the magnet generator. This is to obtain a high secondary voltage.

(Means for solving the problem) Two main capacitors are charged in parallel with the generating coil of the magnet generator, and the signal voltage of the rotation sensor that generates one signal voltage per engine rotation is output to the signal output circuit. As a result, a signal is generated once every two revolutions of the engine, and is separated into two sets of distribution signals, each of which is used as a trigger signal for the first and second semiconductor switching elements.

(Function) The two semiconductor switching elements are made alternately conductive every rotation of the gate, and each main capacitor is discharged.
One of the discharges becomes a regular spark, and the other one becomes a wasteful fire. However, since each main capacitor is charged in parallel by the generator coil, the charged charge when the rotation is high after the compression process can always be used for the regular spark, and therefore the secondary of the ignition coil. A high secondary voltage can be obtained in the coil.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 1 is a power generation coil of a magnet generator, and 2 is a long protruding inductor provided on the outer periphery of a rotor of the magnet generator. Engine (rotor)
The rotation sensors 9 and 10, which rotate one rotation and generate one positive and negative signal voltage, are charged in parallel by the positive direction voltage of the generating coil 1 via diodes 6.7, respectively. The other ends of the second main capacitor are both connected to the primary coil 19a of the same ignition coil 19.

11 and 12 are the first . This is the second Cyrisk. 8 is a DC arc diode connected in parallel with the primary coil 19a of the ignition coil 19; 16 is a regulator consisting of a thyristor 13, a constant voltage diode 14, and a stabilizing resistor 15; The voltage is kept at a constant value by the regulator 16, and the DC power supply capacitor 17 is charged. A signal output circuit 18 receives the signal from the sensor 2 and outputs gate trigger signals for the two Cyrisks 11 and 12.

FIG. 2 shows details of the signal output circuit 18.
Reference numeral 1 designates a known ignition timing control circuit which inputs the positive and negative signals of the sensor 2 and outputs one pulse of the trigger signal of the Cyrisk 11.12 per engine revolution. 27 is resistance 2
3. An inverter circuit consisting of 24, 25, and a transistor 26 receives the positive direction signal of the sensor 2 through the diode 22 and outputs O'' only during this period.On the 2nd, the output of the inverter 27 is input and the output is This is a down-edge operation type T-FF (+- rigger flip-flop) that inverts the state.The Q and Q outputs of this T-FF 28 are each used as one input of two AND circuits 29 and 30, and each of these AND circuits 29 and 30 is used as an input. The output of the ignition timing control circuit 2'1 is connected to the other input terminals of the circuit 29, 30.

The output of one AND circuit 29 is connected to the gate of the first thyristor 11, and the output of the other AND circuit 1830 is connected to the gate of the second thyristor 12.

The operation of this circuit will be explained below with reference to the waveform diagrams of FIGS. 4 and 5. First, the operation of the signal output circuit 18 will be explained with reference to FIG. Sensor 2 generates one cycle of positive and negative signal voltages per engine revolution (Figure 4 (a)).
. In response to this signal voltage, the ignition timing control circuit 21 generates an advance angle signal that rises between the rising position θ of the negative direction voltage and the rising position θH of the positive direction voltage of the sensor signal according to the engine rotation speed. Output. FIG. 4 fbl shows the output waveform of this ignition timing control circuit 21, and here the output waveform is shown in the middle of advancing. On the other hand, the positive voltage of the sensor 2 becomes an input to the inverter circuit 27, and the inverter circuit 2
As shown in Figure 4 (C1), when the positive voltage of sensor 2 rises, the output of 7 falls from "1" to '0°.T-
Since the FF28 is a down-edge operation type, at the same time the output of the inverter 27 falls from 1" to "O", the previous state is reversed, and its Q output changes from "■" to "0", and the Q output also changes from "■" to "0". changes from "0" to "■". This state is maintained until the output of the impark circuit 27 falls from 1'' to ``O'', and the Q and Q outputs are each rotated for each revolution of the engine as shown in FIG. 4 (d+, (el). The state is reversed.

Q, Q outputs are each two AND circuits 29°30
Also, the output of the ignition timing control circuit 2I is the other input of each AND circuit 29.30, so the output of each AND circuit 29.30 is equal to One advance angle signal is output, and each output signal is output alternately every engine revolution. The output waveforms of these AND circuits 29°30 are the 41st (o
, Ig).

Therefore, the thyristors 11 and 12 perform discharge control alternately every rotation of the engine.

Next, the charging voltage of each main capacitor 9 and 10 at the time of starting will be explained. Figure 15 (・) to (・) are
(Instantaneous engine speed N1 when the starter is ON
Signal voltage Vs of sensor 2, each main capacitor 9.10
represents charging voltages VCI and Vc2, respectively.

Here, each charging voltage Vc1. As explained above, Vc2 is discharged once every two revolutions of the engine, and is alternately discharged every one revolution of the engine.

Now, if the starter is turned on at t=Q and the engine starts rotating, each main capacitor 9 is
, 10 are charged simultaneously. Then, the DC power supply capacitor 17 is charged by the negative voltage of the generating coil 1, and the signal output circuit Ift starts operating. Here, T-FF
Whether the Q output of 28 starts from "l" or "o°" is determined by pure chance, but if it starts from Q - "o" (that is, Q = "1"), from the previous explanation, As is clear, the first ignition is caused by the other AN
The second thyristor 12 is turned on by the output of the D circuit 30, and the electric charge of the second main capacitor 18 is discharged, but the spark at this time becomes a wasted flame. On the other hand, the charge in the first main capacitor 9 is not discharged here, but after the T-FF 28 is inverted by the positive voltage of the next sensor signal and becomes Q-"1", one of the AND circuits 29 is output. Discharge occurs only when the first thyristor 11 is turned on by the force. After this, the engine compression process (2
), the rotation speed increases rapidly and the generator coil 1
Since the generated voltage becomes higher, the charging voltage of each main capacitor 9 and 1o becomes higher as shown in the figure. In addition, in order to charge the two main capacitors 9.10 at the same time,
It is often thought that the charging voltage will be lower than when charging one main capacitor, but in reality the rotation speed is low, that is, the frequency is low, so the delay in the current is small, and furthermore, resonance occurs in this low rotation speed region. Due to this phenomenon, the charging voltage will not drop. The charges in the main capacitors 9 and 1o, which were charged during the high rotation after the compression step (2), are alternately discharged every revolution of the engine, as shown in FIG. In other words, the subsequent compression process of the engine!
41. (In 61, each main capacitor 9.10
Since both are discharged at a sufficiently high charging voltage, a sufficiently high voltage is generated in the secondary coil 19b of the ignition coil 19, and the air-fuel mixture can be reliably ignited.

In the embodiment described above, the output of the rotation sensor 2 is connected to T via the diode 22 and the inverter circuit 27.
- Although the output of the ignition timing control circuit 21 is supplied to the T-FF 28, the diode 22 and the inverter circuit 27 may be omitted.
Furthermore, even in a device that does not have the ignition timing control circuit 21, the present invention can be applied by directly applying the output of the rotation sensor 2 to one input of each of the AND circuits 29' and 30.

(Effects of the Invention) As described above, in the present invention, the two semiconductor switching elements are alternately made conductive for each rotation of the engine to alternately discharge the main capacitors, so that only one of them is discharged. The magnet generator generates a regular spark, and the charged charge at high rotation speed after the compression process can be used for the regular spark, and a high secondary voltage can be obtained in the secondary coil of the ignition coil. (and 2 at high speed)
This has the excellent effect of improving ignition performance during starting without causing a drop in voltage.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a more detailed electric circuit diagram of the signal output circuit in the device shown in FIG. 1, FIG. 3 is a waveform diagram of various parts in the conventional device, and FIGS. 4 and 5 are waveform diagrams of various parts for explaining the operation of the above embodiment. be. DESCRIPTION OF SYMBOLS 1... Generator coil, 2... Rotation sensor, 9... First main capacitor, 10... Second main capacitor, 11... First cyrisk forming the first semiconductor switching element , 12...the second semiconductor switch forming the second semiconductor switching element
18...Signal output circuit, 19...Ignition coil, 19a...Primary coil.

Claims (1)

[Claims] In a capacitive discharge type non-contact ignition system for an internal combustion engine that uses a magnet generator as a power source, the first and second main capacitors are charged in parallel by the generator coil of the magnet generator, and each of these capacitors is charged. A first and a second semiconductor switching element for controlling the discharge of electric charge to the primary coil of the same ignition coil, a rotation sensor that generates a signal once per revolution of the engine, and an output signal of this sensor. One signal for every two revolutions of the engine, and the first, first, and
a signal output circuit that generates a second distribution signal, and the first and second distribution signals of the signal output circuit generate the first distribution signal.
, a non-contact ignition device for an internal combustion engine, characterized in that the second semiconductor switching element is made conductive alternately for each revolution of the engine.