JPS5938432B2 - Internal combustion engine ignition circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition circuit for an internal combustion engine, and in particular to an improvement in a current interrupting capacity/discharge combined type ignition circuit.

Ignition of discharge energy based on back electromotive force by cutting off the primary current flowing through the primary winding of the ignition coil, and discharge energy generated by releasing high-voltage charge energy stored separately in an energy storage capacitor. coil
The present applicant has already disclosed several current interrupting capacity discharge combined type ignition circuits that overlap on the next side and obtain synthetic energy on the secondary side, and the air-to-fuel ratio is set thin. It is attracting a lot of attention because it improves the ignition performance of internal combustion engines set at high compression ratios and is resistant to fouling of spark plugs.

Such a circuit requires a high-voltage charging circuit to store energy in the energy storage capacitor of the capacitive discharge section, and conventionally, the output DC voltage of the storage battery mounted on the vehicle is boosted by a DC-DC converter.

On the other hand, with respect to the current interrupting section, it is considered desirable to apply a constant voltage to the ignition coil and the next winding in a steady state.

Therefore, in order to configure a circuit that satisfies both requirements, it is necessary to provide a DC-DC converter for the capacitive discharge section and a stabilizing power supply circuit for current interruption, such as a small and highly reliable switching regulator. It is expected that the configuration will become more complex and the cost will increase significantly.

The present invention has been made in consideration of this point, and by providing the high-voltage charging circuit necessary for the capacitance discharge section and the stabilizing power supply circuit necessary for the current interrupting section with some common components,
This is intended to suppress as much as possible the complexity of the configuration and the increase in cost that would occur if both circuits were provided completely separately.

In the present invention, a small and highly reliable switching regulator is used as the stabilized power supply circuit, and the energy storage reactor used in the known configuration of this type of switching regulator is replaced with a transformer having a step-up winding on the secondary side. The main feature is that it is composed of a primary winding, and the voltage obtained at the secondary winding is rectified and applied to the energy storage capacitor.

That is, an extremely rational configuration was adopted in which the input of the high-voltage charging circuit for the capacitive discharge section is derived from the energy storage reactor of the switching regulator.

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

A storage battery 1 mounted on the vehicle is appropriately charged by an auxiliary device (not shown), and supplies direct current necessary for the operation of the vehicle. A current is supplied to the DC input terminal 5 of the composite ignition circuit 4.

A switching regulator circuit 50 is connected to the input terminal 5.
In this embodiment, the circuit is of a step-down type and has all the basic components of the well-known configuration of this type of circuit.

That is, first, there is a switching circuit 51 that selectively turns on and off the current in the main current line, and in the illustrated embodiment, it is formed by a Darlington connection of transistors 6.7.

The input terminal of the switching circuit 510, ie, the base 8 of the transistor 70, is supplied with a square wave output from a pulse width modulation circuit 9 that sets the switching duty ratio.

Others: diode 13, energy storage reactor 14
, a capacitor 15, and a resistor 11,1 as an error detection circuit.
6, a switching regulator circuit 51 with a feedback line 1γ of the divided voltage output 12 to the pulse width modulation circuit.
It consists of

As a result, the output terminal 1 of this switching regulator
When the voltage at 0 increases beyond a preset value, the width of the output square wave of the pulse width modulator 9 becomes narrower, and conversely, when the output voltage of the switching regulator decreases, the width of the output square wave of the pulse width modulator 9 decreases. The width becomes wider and is inputted to the base input terminal 8 of each Darlington transistor, so that the effect of canceling out the output voltage change is performed.

The constant voltage appearing at the output terminal 10 of such a switching regulator is supplied to the output terminal 19 of this circuit via the choke coil 18, and supplies a constant voltage to the positive terminal 21 of the primary side of the ignition coil via the wiring 20. .

One feature of the present invention, as already outlined, is that the energy storage reactor 1 of the switching regulator section
4 is configured with a primary winding 22a of a transformer 22 having a step-up winding 22b on the secondary side.

The transformer 22 as an energy storage reactor 14
Since a pulsed current flows through the primary winding 22a, a high voltage corresponding to the boost ratio is obtained at the secondary winding 22b.

Therefore, this is rectified and smoothed via a diode 23 and a capacitor 24, and preferably a commutation prevention choke coil 2.
5 to the energy storage capacitor 26,
The required high voltage charging circuit is obtained.

Although the present invention does not directly specify the ignition timing signal generation circuit for current interruption, the trigger circuit for discharging the energy storage capacitor 26, etc., they will continue to be described in one configuration example in the illustrated embodiment. explain.

The ignition timing signal generator or periodic current interrupt device 29 is an example of one that is normally mounted on a vehicle, and the primary negative terminal 27 of the ignition coil 28 is connected to a switching transistor 30 at the output stage of this device 29. Collector electrode 3
Connected to 1.

The rotor 36 rotates in synchronization with the rotation of the engine, causing the signal coil 31 to generate an alternating current in synchronization with the rotation of the engine,
This signal is processed by the signal processing circuit 33 to perform switching.
A signal synchronized with the rotation of the engine is supplied to the base of the transistor 300.

From the signal processing circuit 33, the switching transistor 3
When a forward current is supplied to the 00 base, this transistor is turned on, and the primary coil of the ignition coil 28 is excited to a magnetic saturation state by the current supplied from the output terminal 19 of the ignition device 4.

On the other hand, the capacitive discharge section includes a thyristor 38, which remains off when no signal is input to the gate 39, so that the capacitor 2 for storing discharge energy
6 is charged from the positive output terminal 41 of the high-voltage circuit through the primary winding of the ignition coil 28 and the collector 31 of the switching transistor 30 in the emitter 420 circuit.

When the rotor 36, which rotates in synchronization with the engine, rotates and reaches a predetermined ignition timing, the output signal of the signal processing circuit 33 disappears, and the input current to the base 32 of the switching transistor 300 is cut off. is off.

As a result, the current flowing into the primary coil of the ignition coil 28 is cut off, and the magnetic flux of the iron core of the ignition coil disappears, so that a surge voltage due to a back electromotive force is generated on the primary side of the ignition coil.

The polarity of the surge voltage is determined by the ignition coil 28 when viewed from the ground wire.
The voltage is applied to the trigger input terminal 43 for the capacitive discharge section of the circuit 4 with the polarity such that the negative terminal 27 side of the voltage source is a positive high voltage. This pulse input is given to the primary terminal 45a, and a pulse wave is induced on the secondary side with a positive polarity at one end 45b of the secondary terminal.

As a result, the gate 3 of the thyristor is
9, the thyristor 38 turns on and becomes conductive between the anode and the cathode, so one end 41 of the energy storage capacitor 26 is grounded and the other terminal 19
, the wiring 20, the ignition coil-secondary winding, and the diode 48, and applies discharge energy to the primary winding of the ignition coil in a manner superimposed on the back electromotive force energy accompanying current interruption.

The operation has been explained above, but according to the present invention, although the switching regulator constitutes a constant voltage power supply for cutting off current, there is no need to create a separate high-voltage charging circuit for the capacitive discharge section energy storage capacitor. Since it is possible to avoid this and adopt a rational configuration in which the input is extracted from the energy storage reactor of the switching regulator, a high-performance ignition circuit can be provided with good productivity and at a low price.

In addition, switching regulators are step-up type, buck-boost type,
The present invention can be applied to both types, such as inverter rectifier type, since they all have an energy storage reactor.

[Brief explanation of the drawing]

The drawing is a circuit configuration diagram of an embodiment of the present invention. In the figure, 4 is the ignition circuit of the present invention as a whole, 9 is a duty ratio control circuit, 14 is an energy storage reactor, 22 is a step-up transformer whose primary winding is an energy storage reactor, 26
28 is an energy storage capacitor, 28 is an ignition coil, 29 is an ignition timing signal generation circuit, 50 is a switching regulator, and 51 is a switching section thereof.

Claims (1)

[Claims] 1. A current interrupting section that periodically interrupts the current in the primary winding of the ignition coil in synchronization with the rotation of the engine, and an energy storage capacitor charged at high voltage in synchronization with the rotation of the engine. An ignition circuit for an internal combustion engine of a current interrupting capacitive discharge combination type, comprising a capacitive discharge section that releases stored energy to the primary winding of the ignition coil, the switching circuit supplying a constant voltage to the primary winding of the ignition coil. In addition to providing a regulator, an energy storage reactor provided in the switching regulator is configured with a primary winding of a step-up transformer having a step-up winding on the secondary side, and the secondary output of the step-up transformer is rectified to supply the energy storage capacitor. An ignition coil for an internal combustion engine characterized by obtaining a high-voltage charging output for use.