JPS61182467A - Ingiting device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable widening of the width of a lead angle and to improve starting properties of an engine, by a method wherein a capacitor, which is charged into the one polarity by means of the induction voltage of the other half-cycle of an ignition coil, is provided, and the charged charge is discharged at a given time. CONSTITUTION:An ignition device has a transistor switch 3 for controlling a main current to which a circuit between a collector and an emitter in parallel to an ignition source coil (prmary coil 1a of an ignition coil 1) inducing an a.c. voltage in synchronism with rotation of an engine. The switch 3 is energized when a voltage of one half-cycle is induced to the coil, and is brought into a shut off state with a switch 4 for controlling shut off energized with a voltage between the collector and the emitter is increased to a given value. In which case, a capacitor 5, which is charged by means of an induction voltage of the other half-cycle, is provided, and the charged charge is discharged through the coil and the switch 3 from a point of time when charging is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current interrupt type ignition device for internal combustion.

[Summary of the Invention] The present invention makes a transistor switch connected in parallel to an ignition power supply coil conductive at the output of one half cycle of the ignition power supply coil, and puts the transistor switch in a cut-off state at the ignition timing. A current interrupt type ignition device for an internal combustion engine that obtains a high voltage for ignition by a capacitor that is charged by the output of the other half cycle of the ignition power supply coil, and a charge of the capacitor that is transferred to the ignition power supply coil and a transistor switch. By providing a discharge circuit that discharges through This is what I did.

[Prior Art] In a current interrupt type ignition system for an internal combustion engine using a transistor switch as a current control switch, the main current control transistor switch is connected in parallel to the ignition power supply coil, and one side is connected to the ignition power supply coil. When a half-cycle voltage is induced, the transistor switch is made conductive to short-circuit the ignition power supply coil. Then, the voltage across the transistor switch is detected, and when the voltage reaches a predetermined value, the transistor switch is turned off.

Since the short-circuit current flowing through the ignition power supply coil is blocked by shutting off the transistor switch, a high voltage is induced in the ignition power supply coil. This voltage is further boosted by the ignition coil, and a high voltage for ignition is obtained in the secondary coil of the ignition coil.

In the conventional ignition system of this type, as shown by curve a in Fig. 3, at low speeds at Vs, there is a slight (approximately 2 to 5 degrees)
The ignition timing α advances and thereafter remains approximately constant even if the rotational speed N (rpm) further increases.

By the way, in this type of ignition system, the ignition timing α1 (see Fig. 3) in the medium and high speed range of the engine is set at an appropriate position (different depending on engine II) ahead of the top dead center of the engine. The installation position of the ignition power supply coil is determined by setting the position, but if the ignition timing is determined in the medium and high speed range of the engine in this way, the ignition timing at low engine speeds is automatically determined by the advance width of the ignition system's advance characteristic. become. The appropriate ignition timing in the mid-high speed range of an engine is, for example, about 25 degrees ahead of the engine's top dead center TDC, but in conventional ignition systems of this type, the advance angle range was 2 degrees to 5 degrees. Therefore, if the ignition timing in the medium and high speed range was set at 25 degrees before top dead center, the ignition timing at low speeds was about 20 to 23 degrees before top dead center.

[Problem to be Solved by the Invention 1] In order to stabilize the ignition operation at low speeds of the engine and improve the startability of the engine, it is preferable to bring the ignition timing at low speeds as close to top dead center as possible. If the ignition timing is advanced when the engine is running at low speed, the so-called "Ketchin" phenomenon occurs, in which the engine attempts to reverse the rotation when starting, which not only makes it difficult to start the engine, but also prevents the engine from starting when starting with a kick start. A large repulsive force acts on the driver's legs, and in severe cases, the driver may be injured.

With the above-mentioned conventional current interrupt type ignition device, the advance angle width could only be about 2 degrees to 5 degrees.
It was unavoidable that the ignition timing at low speed for the first engine was 20 to 23 degrees ahead of top dead center TDC. As described above, if the ignition timing is advanced when the engine is running at low speed, the above-mentioned ketching phenomenon cannot be avoided, and the startability becomes unavoidable. Furthermore, if the ignition timing at low speeds is set to an appropriate position in order to improve starting performance, the ignition timing at high speeds of the engine will be delayed too much, which inevitably deteriorates engine performance.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition system for an internal combustion engine that can obtain sufficient advance and color width and set the ignition timing at appropriate positions at both low and medium speeds of the engine.

[Means for Solving the Problems] The ignition device to which the present invention is directed, as shown in FIG. A main current control transistor switch 3 is provided with a collector-emitter circuit connected in parallel to the coil (in this example, the primary coil 1a of the ignition coil 1), and the transistor switch 3 controls the ignition power supply coil in one half cycle. When a voltage is induced, a base current is applied and conduction occurs. A cut-off &llll switch 4 is connected to the transistor switch 3, and the switch 4 becomes conductive when the voltage between the collector and emitter of the transistor switch 3 reaches a predetermined value to turn the transistor switch 3 into a cut-off state.

In such an ignition device, the present invention provides that the capacitor 5 is charged to one polarity by the induced voltage of the other half cycle of the ignition power supply coil, and that the charge of the capacitor 5 is reduced from the time when the charging of the capacitor 5 is completed. The present invention is characterized in that it is provided with a discharge circuit for discharging through the ignition power supply coil and the transistor switch 3.

[Operation of the invention] As described above, the capacitor 5 is provided, and the capacitor 5
is charged by the output of one half cycle of the ignition power supply coil (in this example, the primary coil 1a of the ignition coil), and from the time when charging of the capacitor 5 is completed, the charge of the capacitor is discharged through the ignition power supply coil and the transistor switch 3. In this case, the discharge current of this capacitor flows superimposed on the short-circuit current flowing from the ignition power supply coil through the transistor switch 1 to the transistor switch due to the voltage of one half cycle of the ignition power supply coil. In this way, when the discharge current of the capacitor is superimposed on the current flowing through the transistor switch, the current flowing through the ignition power supply coil (the short-circuit current flowing when the induced voltage of the ignition power supply coil is short-circuited by the transistor switch) The waveform of the current (hereinafter referred to as main current) is as follows when the engine speed N is N1, N2 (>N1), N3 (>
When the rotational speed increases as shown in FIG. 2A to C, the waveform of the rising portion changes significantly as the rotational speed increases. Therefore, the phase at which the main current flowing through the ignition power supply coil reaches the predetermined IIXIIi value will change significantly as the engine speed increases, and if the current cutoff value at the ignition timing is constant, the advance angle width will change significantly as the engine speed increases. will be significantly wider than before.

Therefore, when the ignition timing at medium and high speeds is set to an appropriate position, the ignition timing at low speeds can be set to a position close to top dead center, making the operation of the engine stable at low speeds,
Startability can be improved.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an ignition coil in which a primary coil 1a and a secondary coil 1b are wound around an iron core. One end is grounded, and the (l!! end of the thorny coil 1a is connected to one end of the secondary coil 1b. The other end of the secondary coil 1b is the non-grounded side of the spark plug 2 attached to the cylinder of the engine. It is connected to the terminal via a high voltage cord.At least one thorn coil 1a of the ignition coil 1 is arranged as an armature coil in a magnet generator driven by the engine, and is connected to the primary coil 1a in synchronization with the rotation of the engine. In other words, in this example, the primary coil 1
A also serves as the ignition power supply coil.

Transistor switch 3 is Darlington connected NP
It consists of N transistors TR1 and TR2, and the collector of the transistor switch 3 (the collector of TR1 and TR2) is connected to one end of the primary coil 1a of the ignition coil. The emitter of the transistor switch 3 (the emitter of the transistor TR2) is connected to the anode of a diode 6 whose cathode is connected to the other end of the primary coil 1a, and the base of the transistor switch 3 (the base of the transistor TR1) is connected to the resistor 7. The diode 9 is connected to one end of the primary coil 1a via a diode 8, and the cathode of a diode 9 whose anode is connected to the emitter of the transistor switch 3 is connected to the connection point of the resistors 7 and 8. When the primary coil (ignition power supply coil>1a) induces a voltage of one half cycle in the direction of the solid arrow shown in the drawing, the transistor switch 3 is supplied with a base current and becomes conductive, shorting the primary coil 1a.

The cutoff control switch 4 consists of an NPN transistor TR3 whose emitter is connected to the emitter of the transistor switch 3, and the collector of the transistor TR3 is connected to resistors 7 and 8.
connected to the connection point.

A voltage dividing circuit consisting of a series circuit of resistors 10 and 11 is connected between the collector and emitter of the transistor switch 3, and the base of the transistor TR3 is connected to the connection point of the resistors 10 and 11. A voltage divider circuit consisting of resistors 10 and 11 detects the voltage across the transistor switch 3, and when the voltage between the rectifier and the emitter of the transistor switch 3 reaches a set value, it causes a predetermined base current to flow through the transistor TR3. The transistor TR3 is made conductive. When the transistor TR3 is turned on, the transistor switch 3 is turned off, and a high voltage is induced in the primary coil 1a. This voltage is boosted by ignition coil 1 and 2
A high voltage for ignition is induced in the next coil 1b, and a spark is generated in the ignition plug 2 due to the high voltage, thereby performing an ignition operation.

A diode 12 having an anode directed toward the emitter of the transistor switch 3 is connected in parallel between the collector and emitter of the transistor switch 3 .

The present invention provides such an ignition device with a capacitor 5 that is charged by the output of the other half cycle of the ignition power supply coil, and from the time when charging of the capacitor is completed, the capacitor 5 is connected to the ignition power supply coil and the transistor switch 3. It is designed to cause discharge through the

In this embodiment, a capacitor 5 is connected in parallel to both ends of a diode 6, and when a voltage of the other half cycle in the direction of the dashed arrow shown in the figure is generated in the primary coil (ignition power supply coil) 1a, the capacitor 5 is connected in parallel to both ends of the diode 6. It is designed to be charged polarized.

In the above embodiment, the primary coil 1a induces an alternating current voltage in synchronization with the rotation of the engine. When a voltage in the direction of the dashed arrow shown in the figure is generated in the primary coil 1a, the capacitor 5 is charged through the diode 12 to the polarity shown. When the voltage of the primary coil 1a in the direction of the dashed arrow reaches its peak, charging of the capacitor 5 is completed, and thereafter the charge of the capacitor 5 is discharged through the primary coil 1a and the transistor switch 3. When a voltage of one half cycle in the direction of the solid arrow shown in the figure is generated in the primary coil 1a, a short circuit current flows through the transistor switch 3 due to the voltage, but the discharge current of the capacitor 5 flows superimposed on this short circuit current. . Here, it is assumed that there is no transistor TR3,
Assuming that the transistor switch 3 does not shut off, 1
The waveform of the main current flowing in the secondary coil 1a (current that is a superimposition of the discharge current of the capacitor 5 and the short-circuit current that flows when the induced voltage in the direction of the solid line arrow of the primary coil 1a is short-circuited by the transistor switch 3) is shown in Figure 2. As shown in A to C. The waveform shown by the broken line in FIGS. 2A to 2C is the waveform of the main current flowing through the primary coil 1a when the capacitor 5 and diode 6 are not provided.

That is, when the rotational speed N of the ll function is a rotational speed N1 near the starting rotational speed, the waveform of the current flowing through the primary coil 1a with respect to time t [sec] is as shown in FIG. 2A,
When the rotation speed is low in this way, the short-circuit current of the primary coil 1a rises after the discharge current of the capacitor 5 has passed its peak, so that the main current I flowing through the primary coil 1a increases. A small peak p1 occurs at the rising edge.

When the engine speed increases from N2 to N3, the charging voltage of the capacitor 5 increases and its discharging current increases, and the time for which the discharging current flows becomes longer. The short-circuit current in the next coil begins to rise. Therefore, as the engine speed increases, the primary coil 1a as shown in FIG. 2B and C.
The peak of the rise of the main current I flowing through the main current I disappears, and the rise becomes steeper.

In this way, if we obtain a main current I whose rise changes significantly as the engine speed changes, we can obtain characteristics with a wide advance angle width, as shown by the curve or C in Figure 3. I can do it. That is, the breaking current value at the ignition timing is set to be slightly larger than the peak p1 that occurs at low speeds (when N=N1), for example, as shown in 11 in FIG.
When the main current I reaches the breaking current value 11, the transistor T
R3 is conductive and transistor switch 3 is cut off), the engine speed reaches the set speed Ns and the peak p1 reaches the cutoff current value 11, as shown in the curve in Figure 3. When this happens, the ignition timing can be rapidly advanced.

Furthermore, if the transistor TR3 is set to conduct and the transistor switch 3 is cut off when the main current reaches a sufficiently large cut-off current value I2, the presence of the peak ρ1 will not affect the advance angle characteristic, so as shown in FIG. As shown by curve C, a characteristic of smoothly advancing the angle can be obtained.

In the above embodiment, the primary coil of the ignition coil 1 also serves as the ignition power supply coil, but the present invention also applies when the ignition coil is provided outside the magnet generator and the ignition power supply coil is provided separately from the ignition coil. can be applied. In this case, the ignition power supply coil is connected in parallel to both the star switch 3 and the primary coil 1a.

As mentioned above, when the diode 6 is provided at both ends of the capacitor 5, the capacitor 5 is hardly charged by the voltage in the direction of the solid arrow shown in the ignition power supply coil, so that the capacitor can be easily charged. can. In addition, a small resistor is connected in series with the diode 6, and a capacitor 5 is connected in parallel between both ends of the series circuit of the diode 6 and the small resistor, so that when the transistor switch 3 is conductive, the diode 6 and the small resistor are connected in parallel. It is also possible to apply the voltage generated across the series circuit with the resistor to the capacitor 5. With this configuration, since the capacitor 5 is reverse biased before being charged to the polarity shown, the time when the capacitor 5 is completely charged is delayed. Therefore, the timing at which the peak p1 occurs can be adjusted by adjusting the resistance value of the small resistor connected in series with the diode 6, and the advance angle characteristic can be adjusted.

As mentioned above, in the present invention, the advance angle width can be widened, so if the ignition timing α2 at medium and high speeds is set to an appropriate size in FIG. It is possible to bring the engine closer to top dead center, making it possible to stabilize the ignition operation at low speeds of the engine.

In the above example, the cutoff control switch 4 is connected to the transistor T
Although this switch is configured using R3, it is also possible to configure this switch using a thyristor.

[Effects of the Invention] As described above, according to the present invention, since the advance angle width can be widened, the ignition timing can be set at appropriate positions at both low and medium speeds of the engine. This has the advantage of improving the startability of the engine, and also improving the performance of the engine in the medium and high speed range.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 A to C are waveform diagrams for explaining the operation of Fig. 1, and Fig. 3 is an example of lead angle characteristics obtained by the same embodiment. FIG. 2 is a diagram showing the advance angle characteristics of a conventional device. DESCRIPTION OF SYMBOLS 1... Ignition coil, 1a... Primary coil (also serves as ignition power supply coil in this example), 3... Transistor switch, 4... Shutdown control switch, 5... Capacitor.

Claims (1)

[Claims] When a collector-emitter circuit is connected in parallel to an ignition power supply coil that induces an alternating current voltage in synchronization with the rotation of an internal combustion engine, and one half cycle of voltage is induced in the ignition power supply coil. A main current control transistor switch that conducts, and a cutoff control switch that becomes conductive and turns the transistor switch into a cutoff state when the collector-emitter voltage of the transistor switch reaches a predetermined value, and when the transistor switch is cut off. The ignition device for an internal combustion engine obtains a high voltage for ignition by boosting the voltage induced in the ignition power supply coil, the capacitor being charged to one polarity by the induced voltage of the other half cycle of the ignition power supply coil; An ignition device for an internal combustion engine, comprising a discharge circuit that discharges the electric charge of the capacitor through the ignition power supply coil and the transistor switch from the time when charging of the capacitor is completed.