JPH01151776A - Engine igniter - Google Patents

Abstract

PURPOSE:To vary lead angle continuously as engine rotation increases by providing first and second capacitors to be charged respectively with positive and negative pulses being produced for every rotation of engine. CONSTITUTION:Outputs from a pulser coil 1 which produces a set of positive and negative pulses for every rotation of a magnet are fed to a thyristor igniting circuit A. A capacitor 6 for producing voltage proportional to the rotation of engine is charged with positive pulse, and it is discharged when a negative pulse is generated and a transistor 12 is turned ON. A thyristor 19 is ignited by a negative pulse to discharge an ignition capacitor 20 so as to ignite an engine. Furthermore, a capacitor 7 for producing voltage proportional to time is charged with negative pulse and subsequently discharged approximately in linear through a Zener diode 14 when no negative pulse is provided so as to conduct a thyristor 12 when the voltage of the capacitor 6 exceeds over that of the capacitor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine ignition device that generates a high pulse voltage from an ignition coil to ignite an engine of a vehicle or the like.

[Conventional technology]

The ignition timing of an engine is generally set at a position a certain rotational angle before the position where the piston reaches top dead center. This angle is called the advance angle, and the advance angle needs to be increased (advanced) as the engine speed increases.

Conventionally, when increasing the advance angle as the engine speed increases, the advance angle is increased in steps when the engine speed increases to a certain extent.

[Problem that the invention seeks to solve]

If the advance angle is increased in steps, there is a problem in that it is not possible to finely control the ignition timing of the engine so that it is in the optimum state according to the engine speed.

[Means for solving problems]

In order to solve the above problems, the present invention takes the following measures to enable the advance angle to be increased continuously as the engine speed increases, rather than stepwise.

That is, in the engine ignition system of the present invention, a balsa coil that outputs one positive pulse and one negative pulse per engine rotation, a first capacitor that is charged by the positive pulse and discharged by the negative pulse, and a balsa coil that outputs one positive pulse and one negative pulse per engine rotation, a second capacitor that is charged to a constant voltage and discharged approximately linearly at least over a period from when the first capacitor is charged until it is discharged; The present invention includes a first thyristor that conducts when the first thyristor becomes conductive, and a second thyristor that becomes conductive when the first thyristor becomes conductive and supplies an ignition pulse to the ignition coil.

[For production]

The voltage of the first capacitor rises (charges) during a positive pulse and falls (discharges) during a negative pulse.
.

The voltage of the second capacitor decreases approximately linearly during the period from when the voltage of the first capacitor rises until it falls.

The thyristor that ignites the engine becomes conductive when the voltage on the first capacitor becomes greater than the voltage on the second capacitor, but the voltage on the first capacitor increases continuously as the engine speed increases. Therefore, the time point also changes not stepwise but continuously.

〔Example〕

FIG. 1 shows an engine ignition system according to an embodiment of the present invention. In FIG. 1, 1 is a balsa coil, 2 to 5 are diodes, 6 is a capacitor for generating rotational proportional voltage,
7 is a time proportional voltage generation capacitor, 8 to 11 are resistors, 12 is a transistor, 13 is a thyristor, 14 is a Zener diode, 15 to 18 are resistors, 19 is a thyristor, 20 is an ignition capacitor 1, 21 is an ignition 22 is a diode, 23 is an exciter coil, and 24 is a diode. Block A is a thyristor firing circuit for supplying a firing signal to the thyristor 19. The block B is a well-known CD1 circuit (Con
Denser Discharge Ignition
).

The exciter coil 23 is disposed on the magneto and is configured to generate several cycles of alternating current during one rotation of the magneto. The positive half wave passes through the diode 22 and charges the ignition capacitor 20 to the polarity shown. When the thyristor 19 is ignited, the ignition capacitor 20 is discharged along the path of the thyristor 19 -> the diode 3 -> the ground -> the ignition coil 21. At this time, a high voltage pulse is generated in the ibnirasilane coil 21, which is used to ignite the engine.

(Mechanism of ignition of thyristor 19) The thyristor ignition circuit A is configured to generate an ignition signal using the output of the balsa coil 1. The balsa coil l is arranged to produce a set of positive and negative pulses during one rotation of the magneto.

FIG. 2 shows a waveform diagram of each part of the device shown in FIG. 1.

Figure 2 (a) shows the pulse waveform of balsa coil 1;
B) shows the voltage waveform of the capacitor 7, and FIG. 2(C) shows the voltage waveform of the capacitor 6. The reason why the waveform of capacitor 7.6 is as shown will be explained in the following explanation.

(A) When a positive pulse is output The positive pulse Vp+ of the balsa coil 1 that is output at time t is a charging current in the path of the balsa coil 1 → diode 4 → rotation proportional voltage generation capacitor 6 → diode 3 - balsa coil 1. is applied to charge the rotational proportional voltage generating capacitor 6 to the polarity shown in FIG.

The voltage Vc of the capacitor 6 is as shown in FIG. 2 (c),
It starts up at time t1. Once charged, maintain that voltage. The value of the charging voltage depends on the size of the positive pulse,
Its size is proportional to the number of rotations.

(B) Time t when the negative pulse appears! The negative pulse generated by the pulser coil 1 performs the following three operations.

■ If thyristor 19 has not already been fired by this point, fire thyristor I9.

This is done by allowing a current to flow through the path: pulsar coil l - gate of thyristor 19 - cathode of thyristor 19 - diode 2 - balsa coil 1.

If the thyristor 19 has not been fired by this point, it will be fired by this current. When the thyristor 19 fires, the ignition capacitor 2
0 discharges and ignites the engine.

As will be described later, when the engine speed increases, the thyristor 19 is turned on before a negative pulse is generated.

(2) Charge the time-proportional voltage generating capacitor 7 to the polarity shown in FIG.

This is done by the charging current flowing through the path of pulsar coil 1 - time proportional voltage generating capacitor 7 -> diode 2 -> balsa coil 1.

Since the Zener diode 14 is connected in parallel to the time proportional voltage generation capacitor 7, the charging voltage does not exceed the Zener voltage of the Zener diode 14.

If a voltage is applied to the zener diode 14 in the opposite direction, a small amount of current may flow, so when the negative pulse disappears and charging is completed, the time proportional voltage generating capacitor 7 slowly flows through the zener diode 14. Discharge. Therefore, the voltage Vc of the capacitor 7 has a waveform that slowly decreases approximately linearly as shown in FIG. 2 (b).

The circuit elements (such as the Zener diode 14) are selected so that the state in which the voltage decreases substantially linearly continues at least for a period from when the voltage of the capacitor 6 rises until it falls.

■ Discharge the rotation proportional voltage generation capacitor 6.

This is as follows: pulsar coil 1 - resistor 9 - base of transistor 12 - emic of transistor 12 → diode 2 →
When a base current flows through the transistor 12 through the path of the pulser coil 1, the transistor 12 is turned on. Then, the rotation proportional voltage generation capacitor 6 is connected to the transistor 1.
2 and discharge rapidly. Therefore, the voltage Vc of the capacitor 6 suddenly decreases at time t2 in FIG. 2(c).

(Mechanism for advancing the ignition of the thyristor 19) The ignition timing of the engine is generally set at a position a certain rotational angle before the position where the piston reaches top dead center. This angle is called an advance angle, and the engine's ignition timing needs to be advanced further as the engine speed increases.

In the present invention, the engine is ignited by firing the thyristor 19, so the advance angle is determined by the firing angle of the thyristor 19. That is, as the engine speed increases, it is necessary to start the engine earlier.

The thyristor 19 is activated by supplying a gate current to the thyristor 19 through the resistor 17 when the thyristor 13 is activated. The firing of the thyristor 13 is
The voltage Vc of capacitor 6 applied to its anode terminal is the voltage Vc of capacitor 7 applied to its gate terminal.

This is done when the voltage becomes larger (Vc, >Vc,).

FIG. 3 is a diagram showing a mechanism in which the ignition timing of the engine is advanced as the engine speed increases. This will be explained based on FIG.

Vc in FIG. 3 is the voltage across the capacitor 6 described in FIG. Vc increases as the voltage Vp of the pulser coil 1 increases. Since Vp increases continuously as the engine speed (rpm) increases, Vch also increases as the engine speed (rpm) increases.
m) becomes larger continuously as it becomes larger. The curve in Figure 3 is 41 units.

The number of revolutions increases in the order of c and ii.

Vc in FIG. 3 is the voltage across the capacitor 7 described in FIG. Vc slowly decreases at a constant rate (related to the reverse resistance value of the Zener diode 14) from a maximum value equal to the Zener voltage of the Zener diode 14, and is almost unaffected by changes in engine speed. .

If the voltage Vc of the capacitor 6 is, for example, a curved line, the angle θ3 is reached and the relationship Vc5>Vcl is established. At this time, thyristor 13 is fired.

Thyristor 19 is therefore fired.

As the engine speed increases, the voltage Vc of capacitor 6
When the curve of 6 becomes 8, it fires at the angle θ2. That is, since the rotational speed has increased, the ignition timing of the engine is advanced by θ, -02 in rotation angle.

FIG. 4 is an advance angle characteristic curve, which shows the relationship between rotation speed (rpm) and advance angle. 01 on the vertical axis. θ4 is 01. in FIG. θ
It corresponds to 4.

〔Effect of the invention〕

As described above, according to the present invention, the advance angle can be continuously changed as the engine speed increases by using a pair of positive and negative pulses that are generated during one revolution of the engine. Became.

Therefore, it has become possible to finely control the engine's ignition timing so that it is in the optimal state according to the engine speed.

[Brief explanation of the drawing]

Fig. 1: Engine ignition device according to an embodiment of the present invention Fig. 2: Waveform diagram at various parts of the device shown in Fig. 1 Fig. 3: Engine ignition timing as engine speed increases Figure 4 shows the mechanism by which the speed is accelerated.In the lead angle characteristic curve diagram, ■ is a balsa coil, 2 to 5 are diodes, 6 is a capacitor for generating a rotation proportional voltage, 7 is a capacitor for generating a time proportional voltage, 8 1 to 11 are resistors, 12 are transistors, 13 are thyristors, 14 are Zener diodes, 15 and 1. ．． 18 is a resistor, 19 is a si ν star,
20 is an ignition capacitor, 21 is an ignition coil, 22 is a diode, 23 is an exciter coil, and 24 is a diode. Patent applicant: Sawafuji Electric Co., Ltd. Representative Patent Attorney Mori 1) Hiroshi (3 others) Tsukuri K (Q erjukiri C porridge)

Claims (1)

[Claims] a pulser coil that outputs one positive pulse and one negative pulse per engine revolution; a first capacitor that is charged by the positive pulse and discharged by the negative pulse; and at least a first capacitor that is charged to a constant voltage by the negative pulse. a second capacitor that discharges substantially linearly over a period from when it is charged until it is discharged; and a first thyristor that becomes conductive when the voltage of the first capacitor becomes higher than the voltage of the second capacitor. and a second thyristor that becomes conductive and supplies an ignition pulse to an ignition coil when the first thyristor becomes conductive.