JPS6073062A - Igniter - Google Patents

Abstract

PURPOSE:To improve the firing accuracy when starting under battery capacity drop state, by prohibiting spark discharge irrespective of production of firing control signal for predetermined time interval after engine start except when a synchronous signal is produced. CONSTITUTION:Upon turning on of a starter switch 3, transistor Q3 in prohibition circuit 15 is turned on except when the output from a pulser coil 11 is negative while transistor Q2 is also turned on. When starting under such state as the capacity of battery 11 has dropped considerably, firing control signal may be produced with irregular timing because of temporal deterioration of accuracy of firing control circuit 14 to turn off the power transistor Q1. Here, counter electromotive force of ignition coil 6 is applied on the power transistor Q1, but since it is fedback through transistor Q2, Zener diode ZD1 to the power transistor Q1, the voltage of coil 6 is suppressed to never produce spark discharge from the firing plug 7, resulting in improvement of firing accuracy when starting under battery capacity drop state.

Description

[Detailed description of the invention] The present invention opens and opens the ignition device.

In conventional ignition systems, when starting the engine with an extremely low battery capacity, the starter motor requires a large starting current, which causes the battery voltage to temporarily drop dramatically, for example, by around 4V. In some cases, the accuracy of the ignition control circuit, which generates an ignition control signal based on a synchronization signal synchronized with engine rotation, temporarily decreases, making it impossible to obtain the optimal ignition timing for starting.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ignition system that improves ignition accuracy during engine startup by obtaining optimal ignition timing during the early stages of engine startup.

The ignition device according to the present invention can be used for a predetermined period when starting an engine,
The configuration is such that spark discharge at the spark plug is prohibited, regardless of the generation of the ignition control signal, except when a synchronization signal synchronized with engine rotation is generated.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention. In the figure, 1 is a battery, 2 is a main switch, 3 is a starter switch, 4 is a starter relay, 5 is a starter motor, 6 is an ignition coil, and 7 is a spark plug. A rotor 8 has a projection 8a and is made of a ferromagnetic material, and rotates together with the crankshaft of an engine (not shown).

Reference numeral 9 denotes an electromagnetic pickup arranged close to the rotor 8. A balsa coil 11 is wound around the circumference of a magnetic core 10, and is biased by a permanent magnet 12.

When the rotor 8 rotates in the direction of the arrow in the figure and its protrusion 8a passes in front of the magnetic core lO of the electromagnetic pickup 9, a timing pulse (synchronization signal) with a waveform as shown in FIG. 2 is generated at the output end of the balsa coil II. Occur. In FIG. 2, a positive timing pulse a is generated when the front end of the protrusion 8a faces the magnetic core 10 of the electromagnetic pickup 9, and a negative timing pulse b is generated when the rear end of the protrusion 8a faces the magnetic core lo.

The phase of the crankshaft at the time of generation of each timing pulse a and b corresponds to the maximum ignition timing (advance end timing) θa and the latest ignition timing (initial ignition timing) θb of the advance angle characteristics shown in FIG. As you do,
The angle of the protrusion 8a of the rotor 8 and the attachment angle to the crankshaft are set.

Reference numeral 13 denotes an ignition circuit, which is connected in series with an ignition control circuit 14 that generates an ignition control signal based on timing pulses a and b, and the primary winding s 6a of the ignition coil 6, and is turned off in response to the ignition control signal. A power transistor that generates a high voltage in the secondary winding of the ignition coil 6, 6b, and causes a spark discharge in the spark plug 7; The ignition control circuit 14 is comprised of a prohibition circuit 15 that prohibits spark discharge in the ignition plug 7 regardless of the generation of the ignition control signal except when the ignition control signal is generated, and a driving power supply section 16 for the ignition control circuit 14.

In the inhibit circuit 15, a transistor Q2 and a Zener diode ZD□ are connected in series between the collector and base of the power transistor Q1.

The Zener diode ZD
It has z. A resistor R, R2 and a transistor Q3 are connected in series between the collector of the transistor Q2 and the ground, and a transistor Q is connected to the common connection point of the resistors R, R2.
2 bases are connected.

The base of the transistor Q3 is grounded via a resistor R3, and further connected to the output terminal of the starter switch 3 via resistors R4r, R5, and R6. A common connection point of resistors R4r and R5 is connected to the output end of the pulser coil 11 through a resistor R7 and a diode D. Resistance R5+ R
A Zener diode ZD2 is connected between the common connection point of 6 and the ground. Here, when the starter switch 3 is on, the starter signal of approximately battery voltage is applied to the resistor R6.
and Zener diode ZD2 to make it a constant voltage, and resistor R
Pulsar coil II via 5r R7 and diode D
The voltage at the voltage dividing point (A) divided by these voltages is applied to the base of the transistor Q3 via the resistor R4. Each resistance value is set so that when timing pulse b (for example, -0.5V) is induced, transistor Q3 is turned off.

The power supply unit 16 includes a capacitor C that is charged by the battery voltage via a resistor R8, and a Zener diode ZD3 for charging the capacitor C with a constant voltage.

Next, the operation of the present invention will be explained.

Normally, the ignition control circuit 14 generates an ignition control signal as shown in FIG. 4(b) in response to the pulsar output as shown in FIG. 4(a), and this ignition control signal (b) is high. At the falling timing of the transition from the high level to the low level, that is, the timing when the power transistor Q1 transitions from the on state to the off state, a very large voltage is applied to the primary winding 6a of the ignition coil 6 as shown in FIG. A back electromotive force is generated, which causes the secondary winding 5b and the VCI secondary winding 6a and 2 to
Since a high voltage that is twice as high as the turn ratio of the next winding 6b is generated, spark discharge occurs in the ignition plug 7.

When the starter switch 3 is turned on when starting the engine, the transistor Q3 in the prohibition circuit 15 is turned on and the transistor Q2 is also turned on if the pulser output is not negative. When starting the engine with an extremely low battery capacity, the ignition control circuit 14 may temporarily lose its accuracy, and as shown in FIG. In some cases, the ignition control signal (b) is output from the ignition control circuit 14, and in this case, the power transistor Q1 is turned off at the ignition timing when the ignition control signal (b) changes from a high level to a low level. At this time, the back electromotive force of the ignition coil 6 is applied to the collector of the power transistor Q1, but this voltage is fed back to the base of the power transistor Q1 through the transistor Q2 and the Zener diode ZD.
The collector voltage (C) of the power transistor Q, that is, the primary voltage of the ignition coil 6, is suppressed to approximately the Zener voltage Z of the Zener diode ZD, so the secondary voltage of the ignition coil 6 is suppressed to a low voltage and ignition occurs. No spark discharge occurs in the plug 7.

At the initial ignition timing, that is, when the nihalcer output (a) is a negative timing pulse as shown in FIG. Since the inhibition circuit 15 becomes inactive, the primary voltage of the ignition coil 6, that is, the power, instantly becomes high voltage at the timing when the ignition control signal (b) transitions from a high level to a low level and the power transistor Q1 turns off. Collector voltage of transistor Q1 (
C) is not suppressed, and therefore spark discharge occurs at the spark plug 7.

That is, while the starter signal is being applied, even if the ignition control circuit 14 turns off the power transistor Q1 at a timing other than the initial ignition timing, the prohibition circuit 15 suppresses the primary voltage of the ignition coil 60 and prevents the spark plug 7 from turning off. Since spark discharge is prohibited, spark discharge occurs in the spark plug 7 only at the initial ignition timing.

Note that since the prohibition circuit 15 operates in response to the starter signal, it does not affect the ignition operation at any time other than when starting.

As explained above, according to the present invention, sparks are discharged at the spark plug regardless of the generation of the ignition control signal except when a synchronization signal (negative timing pulse) synchronized with the engine rotation is generated during a predetermined period when the engine is started. Since the engine is configured to prohibit this, it is possible to obtain the optimum ignition timing in the initial stage of startup, and it is possible to improve the ignition accuracy when starting the engine, especially when the battery capacity is extremely low.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing one embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
Figure 3 is a diagram showing the advance angle characteristics, Figure 4 is a waveform diagram of each part of Figure 1 during normal ignition operation, and Figure 5 is the initial ignition timing when starting the engine. FIG. 6 is a waveform diagram for explaining the operation at the initial ignition timing when starting the engine. Explanation of symbols of main parts 1...Battery 3...Starter switch 4...
Star'') Ray 6...Ikunino/Yonko 7...Spark plug Il 11...Pulsa coil 14...Ignition control circuit 15
...Prohibited circuit applicant Honda Motor Co., Ltd. agent Patent attorney Motohiko Fujimura

Claims (1)

[Claims] An ignition device comprising means for generating an ignition control signal based on a synchronization signal synchronized with engine rotation, and generating a spark discharge in a spark plug in response to the ignition control signal, the ignition device generating a spark discharge for a predetermined period when the engine starts, An ignition device comprising means for inhibiting the spark discharge regardless of the generation of the ignition control signal except when the signal is generated.