JPS5923066A - Contactless ignition device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable to control an electric current passing angle without being affected by the waveform of a voltage generated by a pick-up coil, by a method wherein a rectangular wave signal and charging and discharging signals for a capacitor are obtained from a pick-up signal, and the thus obtained signals are made to be signal waveforms. CONSTITUTION:An AC voltage Vp of the pick-up coil 1 is subjected to a waveform-shaping treatment by an input circuit 2 to produce the rectangular wave signal. The rectangular wave signal is inputted into one-shot circuits 3, 5 to obtain a hold timing signal and a discharging signal for the capacitor 7. On the other hand, the capacitor 7 is supplied with a constant electric current I from a constant electric current source 8, whereby a bias signal is obtained. Accordingly, since the current-passing time is controlled by utilizing the charging and discharging waveforms for the capacitor without utilizing the voltage generated by the pick-up coil, the electric current passing angle can be controlled without being affected by the waveform of the voltage generated by the pick-up coil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact ignition device for an internal combustion engine, and more particularly to a non-contact ignition device for an internal combustion engine that is provided with means for controlling the energization time of a primary current flowing to the primary side of an ignition coil. It is.

Ignition coil primary current flow time control in a non-contact ignition system for an internal combustion engine generally includes a transistor that controls conduction or disconnection of the primary current, a pickup coil that generates an alternating current voltage in synchronization with the rotation of the engine, This is accomplished by including a voltage detection circuit that controls the starting point of energization of the transistor based on the alternating current voltage.

However, in this method of controlling the energization start point of the transistor using the voltage waveform generated by the pickup coil, the energization start point varies depending on the variation in the generated voltage. In reality, the accuracy of the shape of the pickup coil is strictly controlled so that the voltage waveform generated by the pickup coil falls within a small variation range.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device capable of controlling the starting point of energization of the transistor without being affected by the voltage waveform generated by the pickup coil.

The present invention will be explained below using the embodiment shown in FIG. 1 and the time chart shown in FIG. (A) to (J) in Figure 2
For convenience, the waveforms shown in each of
) signal or (J) waveform or (J) signal.

In Fig. 1, the pickup coil 1 is shown in Fig. 2(A).
An alternating current voltage Vp is generated as an ignition timing signal as shown in FIG. This Vp signal is subjected to waveform processing in the input circuit 2, and is shown in FIG.
A rectangular wave signal as shown in B) is assumed.

(B) Input the signal to the first one-shot circuit 3, and
A one-shot signal (C) is obtained. The signal (C) becomes a hold timing signal that turns the transistor 4 ON and OFF. The output signal of the one-shot circuit 3 is input to the second one-shot circuit 5, and the second one-shot signal (D
). (D) Signal turns transistor 6 ON and OFF
This becomes the discharge timing signal for the capacitor 7.

On the other hand, constant current I supplied from constant current source 8 charges capacitor 7 through resistor 9 . At this time, a waveform as shown in FIG. 2(E) is generated at the contact point 10 between the resistor 9 and the constant current source 8. That is, the terminal voltage waveform of the capacitor 7 is raised by V2=I·R1.

The terminal voltage of the capacitor 7 is appropriately amplified through the first amplifier 11 and the second amplifier 12, and the output waveform of the amplifier 12 is obtained as shown in FIG. 2(F). At this time, the (F) waveform is raised by the voltage of V3,
This is because the power supply voltage signal is input to the amplifier 12 through the resistors 13 and 14, and when the power supply voltage is high, V3 is also high, and when the power supply voltage is low, V3 is also low.

Now, the waveform (F) is peak bolded by the one-shot signal (C), and the terminal voltage of the capacitor 15 is (
G) Obtain voltage waveform V1. This (G) voltage waveform and the above (
By comparing the F) waveform with the comparator 16, the (H) signal is obtained. The (H) signal is input to the synthesis/switching circuit 17 to obtain the (I) signal. (I) The signal is input to the drive circuit 18 and turns on the power transistor 19 for T2 time.
Then, a current (J) is applied to the primary winding of the ignition coil 20.

The purpose of operation of the rotation speed detection circuit 21 is to operate when the engine rotation speed falls below a certain set rotation speed, operate the synthesis/switching circuit 17, and cut off the signal from the comparator 16. However, the signal from the input circuit 2 is input to the drive circuit 18 as is. This is because as the engine speed decreases, T1 in Figure 2 becomes longer and the waveform (
E) and (F) are saturated at the value determined by the power supply voltage,
This is necessary to prevent the primary winding current conduction time T2 from becoming abnormally long.

Now, with the above configuration, it is possible to optimally set the primary winding current energization time according to the constant of the ignition coil used, without being affected by the voltage generated by the pickup coil. Become.

As explained above, according to the first invention of the present application, the ignition coil 1 Since the secondary winding current conduction time is controlled, there is an advantage that the primary winding current conduction time can be controlled without being influenced by the voltage waveform generated by the pickup coil.

Further, according to the second invention of the present application, since a means for amplifying the terminal voltage of the capacitor is provided, it becomes possible to freely change the slope θ of the waveform shown in FIG. It has the advantage of being able to more optimally control the ignition coil primary current energization time from low speed range to high speed range.

Furthermore, according to the third invention of the present application, the hold voltage value has power supply voltage dependence characteristics and the ignition coil primary current energization time is changed depending on the power supply voltage, so even if the power supply voltage changes. This has the advantage that the maximum value of the primary current can be adjusted to be constant, and the ignition energy does not change due to fluctuations in the power supply voltage.

In addition, the starting point of the transistor that controls conduction or disconnection of the primary winding current of the ignition coil is controlled by the output signal of the input circuit or the output signal of the comparator, whichever is earlier. This has the effect that even if the operating state of the engine changes rapidly, the ignition coil primary winding current conduction time guarantees at least the output signal width of the input circuit.

In addition, when the engine speed drops below a certain set number, the ignition coil primary current energization time is controlled by the output signal of the input circuit, so the ignition coil primary current energization time becomes abnormally long in the extremely low speed range. It has the effect of eliminating things.

According to the fourth invention of the present application, since the current charging (or discharging) the capacitor from a power source unrelated to the ignition position signal is a constant current, the terminal voltage of the capacitor is raised (or lowered) by a certain level. ), a simple method of inserting a resistor into the charging (or discharging) circuit can be used.

Although the above-mentioned embodiment has been described with reference to a single-cylinder engine, it goes without saying that the present invention can also be applied to a multi-cylinder engine.

[Brief explanation of drawings]

Fig. 1 is a circuit connection diagram of one embodiment of the present invention, and Fig. 2 is a circuit connection diagram of an embodiment of the present invention.
FIG. 3 is an operation waveform diagram for explaining the embodiment shown in the figure. FIG. 3 is a partial circuit diagram, FIG. 4 is a circuit connection diagram of another embodiment of the present invention, and FIG. 5 is a waveform diagram explaining its operation. 1...Pickup coil, 2...Input circuit, 3,
5... One-shot circuit, 4, 6, 27, 28 transistor, 7, 15... Capacitor, 8... Constant current source, 9, 13, 14... Resistor, 11, 12... Amplifier , 16... Comparator, 17... Synthesis/switching circuit, 18
...Drive circuit, 19...Power transistor,
20... Ignition coil, 21... Rotation speed detection circuit, 2
2...Rotor, 29...One-shot signal processing circuit.

Claims (1)

[Scope of Claims] 1) Means for generating an ignition position signal in synchronization with engine rotation, an input circuit for generating a rectangular wave signal based on the ignition position signal, and conduction of a primary winding current of an ignition coil. A transistor for controlling cut-off, and means for charging (or discharging) the capacitor from a power supply unrelated to the ignition position signal, and raising (or lowering) the terminal voltage of the capacitor by a certain level. means for discharging (or charging) the capacitor based on the input circuit signal; means for holding the terminal voltage of the capacitor based on the input circuit output signal; A comparison circuit is provided for comparing a waveform obtained by raising (or lowering) the terminal voltage of a capacitor by a certain level, and the current conduction start point of the transistor is controlled according to the output of the comparison circuit. Non-contact ignition device for internal combustion engines. 2) means for generating an ignition position signal in synchronization with engine rotation; an input circuit for generating a rectangular wave signal based on the ignition position signal; and controlling conduction or disconnection of the primary winding current of the ignition coil. means for charging (or discharging) the capacitor from a power supply unrelated to the ignition position signal, and means for raising (or lowering) the terminal voltage of the capacitor by a certain level; , means for discharging (or charging) the capacitor based on the input circuit signal, means for amplifying the terminal voltage of the capacitor, and means for holding the amplified signal based on the input circuit output signal; A comparison circuit is provided that compares the held voltage with a waveform obtained by raising (or lowering) the terminal voltage of the capacitor by a certain level, and determines the starting point of energization of the transistor according to the output of the comparison circuit. A non-contact ignition device for an internal combustion engine characterized by controlling. 3) means for generating an ignition position signal in synchronization with the rotation of the engine, an input circuit for generating a square wave signal based on the ignition position signal, and a transistor for controlling conduction/cutting of the primary winding current of the ignition coil. means for charging (or discharging) the capacitor from a power supply unrelated to the ignition position signal; and means for raising (or lowering) the terminal voltage of the capacitor by a certain level; means for discharging (or charging) the capacitor based on an input circuit signal; means for amplifying the terminal voltage of the capacitor; means for inputting power supply voltage characteristics into the amplification section; and means for inputting the amplified signal to the input circuit. means for holding based on a circuit output signal; and a comparison circuit for comparing the held voltage with a waveform obtained by raising (or lowering) the terminal voltage of the capacitor by a certain level; The conduction or disconnection of the transistor is controlled by the output signal or the output signal of the comparator circuit, whichever comes first, or by the input circuit output signal only when the engine rotation speed falls below a certain set value. A non-contact ignition device for an internal combustion engine, which is characterized by: 4) In the device according to any one of claims 1 to 3, the charging (or discharging) current for charging (or discharging) the capacitor from a power source unrelated to the ignition position signal is a constant current. A non-contact ignition device for an internal combustion engine, characterized in that a resistor is inserted in the charging (or discharging) circuit as a means for raising (or lowering) the terminal voltage of the capacitor by a certain level.