JPS599752B2 - magneto igniter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact type electronic ignition device for a magneto, and particularly to one that controls the ignition timing according to the rotation of an engine.

Conventionally, this type of engine ignition system generates an ignition voltage on the secondary side of the ignition coil by opening and closing a semiconductor switching element such as a thyristor or transistor in response to an ignition signal generated at the ignition timing of the engine. The ignition timing is automatically determined by the ignition signal waveform generated in synchronization with the rotation of the engine.

In other words, it was possible to meet the requirements for advance angles to prevent sagging in the low speed range, but if retardation characteristics were required to maintain engine horsepower in the medium to high speed range, then The drawback was that it could not meet the demands.

This invention eliminates the above-mentioned drawbacks, and also obtains highly accurate ignition timing characteristics from medium to high speeds as described below, and in the event that the control circuit malfunctions, it returns to advance control using the conventional ignition signal waveform. The present invention provides a magneto ignition device that enables the following.

The present invention will be described below with reference to embodiments shown in FIGS. 1 to 6.

First, in FIG. 1 showing a CDI type magneto ignition system, reference numeral 1 denotes a magneto power generation coil (not shown), which is a power supply device, and generates positive and negative alternating current voltages in synchronization with the rotation of the engine.

2 and 3 are diodes that rectify the output of this generator coil,
4 is a capacitor charged by the output of the generator coil 1 rectified by this diode 2, 5 is an ignition coil connected to the discharge circuit of this capacitor, and a primary coil 5a/ignition connected in series with the capacitor 4. Plug 6
and a secondary coil 5b connected to the secondary coil 5b.

A thyristor 7 is a switching element provided in the discharge circuit of the capacitor 4, and when the thyristor 7 is conductive, the charge of the capacitor 4 is discharged to the primary coil.

Reference numeral 8 denotes a signal coil for generating an ignition signal, which is a first angular position detection device, which is synchronized with the rotation of the engine and generates a first angular signal a corresponding to a predetermined crank position of the engine.

Reference numeral 10 denotes a signal coil for generating an ignition signal, which is a second angular position detection device, and a second angular signal corresponding to a crank position delayed by θ degrees from the generation position of the first angular signal a and having a wide angular width. generate b.

9 and 11 are diodes for blocking backflow; 12 and 13 are resistors connected to the gate of the thyristor 7; 14 are transistors connected to bypass the second angle signal b to ground; 15 are the above-mentioned This is an ignition timing calculation circuit that starts calculation in response to the first angle signal a and calculates the ignition timing according to the operating state of the engine, and its output is connected to the base of the transistor 14 via a resistor 16.

The signal coil 10 is connected to the resistor 16 and the transistor 14.
A control circuit 30 is configured to omit the output voltage b.

Details of the above-mentioned ignition timing calculation circuit 15 will be described later using FIG. 3.

Next, FIG. 2 shows the mechanical parts of the first and second angular position detection devices. A plurality of permanent magnets 20 are adjacent to each other and have different polarities.

Reference numeral 18 denotes holes or notches serving as magnetic modulation sections, which are provided at two equiangular positions on the circumference of the flywheel 17, and the angular width in the circumferential direction of the magnetic modulation sections (holes) 18 is equal to
It is set smaller than that of .

Reference numeral 19 denotes a first stator core that is disposed opposite to the flywheel 11 in the radial direction with a small gap therebetween, and is connected to the signal coil 8.
is wound around the flywheel 17, and generates a signal voltage in the signal coil 8 by coming into contact with and separating from the magnetic modulation section 18 as the flywheel 17 rotates.

Reference numeral 21 denotes a second stator core which is disposed opposite to the permanent magnet 20 in the radial direction with a small gap therebetween, and around which the signal coil 10 is wound. A signal voltage having an angular width wider than the angular width of the signal coil 8 is generated in the signal coil 10.

Next, FIG. 3 shows a detailed circuit of the ignition timing calculation circuit 15.
In the figure, 22 is a waveform shaping circuit that shapes the waveform of the output of the signal coil 8, and is composed of resistors 221, 222, 223, a voltage comparator (hereinafter referred to as a comparator) 224, a capacitor 225, and a diode 226.

23 is a flip-flop circuit; 24 is an arithmetic circuit connected to this flip-flop circuit 23 and generates a predetermined output according to the engine speed; resistors 241, 242, 24;
3,246,247 diodes 244, 245, capacitor 240, operational amplifier (hereinafter referred to as operational amplifier) 24
8, a voltage comparator (hereinafter referred to as a comparator) 249.

This is a rotation speed-voltage conversion circuit (hereinafter referred to as an F-V circuit) which captures the shaped output of the output signal a of the signal coil 8 as a rotation speed signal and converts it into a DC voltage proportional to the rotation speed.

One input terminal S of the flip-flop circuit 23 is
It is connected to the output terminal of the waveform shaping circuit 22, and the other input terminal R is connected to the output terminal of the comparator 249.

One output terminal Q of the flip-flop circuit 23 is connected to the inverting input terminal (
(hereinafter referred to as the (d) terminal), and is also connected to the (f) terminal of the operational amplifier 248 via a series circuit of a diode 245 and a resistor 243.

A non-inverting input terminal (hereinafter referred to as (G) terminal) of the operational amplifier 248 is connected to the output terminal of the F-V circuit 25 via a resistor 241 and a diode 244, and is connected to a constant power source (not shown) by resistors 246 and 247. It is biased by dividing the voltage.

The output terminal of the operational amplifier 248 is the comparator 249
is connected to the (d) terminal of the capacitor 24.
The non-inverting input terminal (T) of the comparator 249, which is connected to the (→ terminal) of the operational amplifier 248 via the terminal 0, is grounded.

FIG. 4 shows the output characteristics of the F-V circuit 25.
250 is an example of the characteristic, and the figure shows a case where it changes linearly.

Further, as shown in the figure, in this characteristic 250, the voltage Vr1 at the rotation speed N2 is set equal to the bias voltage of the operational amplifier 248.

Therefore, the (G) terminal voltage of the operational amplifier 248 has the characteristic 25
It changes like 1.

Next, FIG. 5 shows output waveforms at each point A to G in the circuit shown in FIG. 3, where the horizontal axis represents time and the vertical axis represents a time chart of voltage.

In the figure, a indicates the angular position of the engine crank, M indicates a position advanced by a predetermined amount from the maximum advanced angle position required by the engine, and a first angle signal b is generated.

S indicates the generation position of the second angle signal g, and T indicates the top dead center of the engine.

Next, the operation of the embodiment will be explained.

First, in the CDI type magnetic ignition system shown in FIG. When a is input, the thyristor 7 is made conductive at the time when the output of the ignition timing calculation circuit 15 or the time when the output voltage b of the signal coil 10 is generated, and the primary coil 5a of the ignition coil 5 is discharged, and the secondary coil 5b receives a high voltage. This generates voltage and causes the spark plug 6 to emit a spark.

Now, the conduction timing control of the thyristor 7, which is the gist of the present invention,
That is, the control of the ignition timing will be explained in detail using the ignition timing characteristic diagram shown in FIG.

Here, for convenience of explanation, the engine is rotating at a constant speed higher than the rotation speed N2 and lower than N3 shown in FIG. At a position advanced by α, the operation is as follows.

First, the F-V circuit 25 counts or integrates the output voltage corresponding to the engine speed, and the output voltage 250 is higher than the bias voltage Vrl.

This output voltage 250 becomes the input voltage of the operational amplifier 248, and the (a) terminal voltage 251 of the operational amplifier 248 changes linearly as the rotation increases, as shown in FIG.

On the other hand, the flip-flop circuit 23 is set by the rise of the output voltage C to the high level at the angular position M of the engine, and its output voltage E becomes the high level.

When the output voltage E reaches the NO level, the capacitor 240, which had been charged with the polarity shown in FIG.
begins to discharge.

As can be understood from the above equation, the magnitude of this discharge current 12 is equal to the magnitude of the operational amplifier 248 if the resistance value of the resistor 242 is constant.
(a) depends on the terminal voltage 251, and eventually the F-V circuit 25
It depends on the output voltage 250 of .

That is, as the engine speed increases, the discharge current 12 becomes smaller, so the slope of the output voltage D of the operational amplifier 248 becomes gentler, and the angular width of the high-level output voltage E of the flip-flop 23 becomes narrower.

The angular width of the high-level output voltage E obtained as described above corresponds to the calculation result of the calculation circuit 24.

Next, as the capacitor 240 starts discharging, the operational amplifier 2
The output voltage D of 48 drops as shown in FIG.

The flip-flop circuit 23 is reset when the reset pulse is input to its input terminal R, and its output voltage E becomes low level.

As described above, when the output voltage E of the flip-flop circuit 23 becomes low level, the capacitor 24 shown in FIG.
0 begins to be charged again with the current 11 shown in the following equation to the polarity shown.

As can be understood from the above equation, if the resistance values of the resistors 243 and 242 are constant, the magnitude of the charging current 11 depends on the (a) terminal voltage 251 of the operational amplifier 248, and eventually F-V
The charging current 11 depends on the output voltage 250 of the circuit 23, and as the rotational speed increases, the charging current 11 increases, and therefore the slope of the output voltage D of the operational amplifier 248 becomes steep.

As described above, in this region, as the rotational speed increases, the angular width of the high level output voltage E of the flip-flop 23 becomes wider.

Now, if the output voltage E of the arithmetic circuit 15 obtained by the operation described above is supplied to the base of the transistor 14 via the resistor 16, the transistor 14 becomes conductive during the level period of the output voltage E, and the signal coil 10 outputs. In other words, since a part of the voltage is omitted as shown in FIG. 5G, the gate signal of the thyristor 7 has a voltage waveform as shown in FIG. 5G.

That is, when the engine speed is in the rotation range from N1 to N3, the flip-flop 23 increases as the engine speed increases.
Since the fall timing of the output voltage E from the high level to the low level is gradually delayed, and therefore the timing of conduction of the thyristor I is delayed, the ignition timing is retarded as the engine speed increases.

Then, when the engine speed reaches N3, the F-V circuit 2
Since the output voltage 250 of No. 5 and the (a) terminal voltage 251 of the operational amplifier 248 are constant, the charging and discharging currents i1 and i2 of the capacitor 240 are constant values regardless of the rotation speed.

As a result, the falling timing of the output voltage E of the flip-flop 23 from the high level to the low level remains constant regardless of the increase in the engine speed, and therefore the ignition timing of the engine is retarded and then becomes the same as shown in FIG. 28 is constant.

On the other hand, the operation in the region where the rotational speed is lower than N2 and higher than N1 as shown in FIG. 6 will be explained.

Even in this rotation range, the calculation circuit 15 calculates the calculation result according to the rotation of the engine as described above, that is, the time when the pressure E of the flip-flop 23 falls to 1 [-level color low level] is determined according to the rotation. As shown on the right side of FIG. 5G, the output voltage b of the signal coil 10 (F shown in FIG. 5) changes depending on the output voltage of the thyristor 1 while the output voltage E of the flip-flop 23 is at a high level. Since the trigger voltage vG has not been reached, the calculation result of the calculation circuit 15 does not contribute to the control of the ignition timing.

Therefore, in this rotation region, the signal coil 1 with a wide angular width
Since the conduction timing of the thyristor 7 is controlled only by the output voltage waveform b (G shown in FIG. 5) of 0, the advance angle characteristic as shown in FIG. 6 is obtained.

This is because the output voltage of the signal coil 10 having a wide angular width grows as the rotation increases, and the angle at which it reaches the trigger voltage VG of the thyristor 7 with respect to the top dead center T becomes earlier.

In addition, the operation of the arithmetic circuit 15 during rotation at a rotation speed N1 or less will be described.

As is clear from Fig. 4 below the rotational speed N1, F-V
Since the output voltage 250 of the circuit 25 is lower than the bias voltage Vr1, the charging and discharging currents i1 and i2 of the capacitor 240 are constant values regardless of the rotation speed.

Therefore, below the rotational speed N1, the flip-flop circuit 23
The angular width of the output voltage E from high level to low level is constant regardless of rotation.

Here, as mentioned above, when the rotation speed is below N1, the output voltage b (G shown in FIG. 5) of the signal coil 10 will not reach the conduction voltage vG of the thyristor 7 while the output voltage E is at a high level. Even if there is a rotation range, the ignition timing is advanced in waveform due to the growth of the output voltage of the signal coil 10, and its advance characteristics are such that the ignition timing is advanced as the rotational speed increases as shown in 26 in Fig. 6. Become.

As can be clearly understood from the above explanation of the operation, in the rotation range until the rotational speed reaches N1, the falling timing of the output voltage E of the arithmetic circuit 24 from the high level to the low level is constant, and the falling timing is constant. The output voltage of the signal coil 10, that is, the point G
Since the output voltage remains constant until the output voltage reaches the trigger voltage vG, the ignition timing advances as the rotational speed increases as the output voltage waveform of the signal coil 10 grows, as indicated by 26 in FIG.

Further, in the rotation range from N1 to N2, the fall timing is gradually delayed, but the output voltage G is still equal to the trigger voltage V.

As described above, the ignition timing changes as the output voltage waveform of the signal coil 10 grows.
As shown in Fig. 6, the angle advances as the rotational speed increases, and in the rotational range where the rotational speed reaches N2, increases, and reaches N3, the angular width of the high-level output voltage E increases as shown in Fig. 5. As the dead points α3, α2, and α1 gradually become narrower, the falling timing is gradually delayed as the rotation speed increases, and the bypass period of the output voltage of the signal coil 10 becomes longer, so that the ignition timing is at the 6th point. As shown in 27 in the figure, the angle is retarded as the rotational speed increases.

Further, in the rotation range where the rotational speed is N3 or more, the falling timing is constant, so the ignition timing is constant at a retarded angle.

The advance angle characteristic 26 of the ignition timing characteristic can be arbitrarily set by changing the output voltage waveform of the signal coil 10 according to the request, and the retard characteristic 27 and constant angle 28 can be set as desired by changing the output voltage characteristic 25 of the F-V circuit 25. Alternatively, it can be set arbitrarily by changing the bias voltage Vrl and changing the output voltage characteristic 251 according to the request.

By the way, in the unlikely event that the arithmetic circuit of the device of this embodiment breaks down, the engine may experience retardation characteristics 27. If 28 is not required, by disconnecting the arithmetic circuit 24 and the control circuit 30, it becomes possible to obtain only the waveform advance characteristic 26 for the ignition timing, and the engine ignition occurs when the rotation speed exceeds N2. becomes possible.

Note that the technical idea of the present invention includes various embodiments within the scope of the claims.

As described above, in the ignition timing characteristics required by the engine, the retard characteristic portion is determined by the ignition timing calculation circuit in response to the first angle signal having a narrow angle width, and the portions other than the retard characteristics are determined by the ignition timing calculation circuit. Utilizes the growth of the signal waveform as the rotation of the second angle signal increases, which corresponds to a crank position delayed by a predetermined angle from the generation position of the first angle signal and has a wider angular width than the first angle signal. Since the retardation angle is determined based on the engine's output characteristics, highly accurate retardation characteristics required by the engine due to its output characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, FIG. 2 is a front view of main parts showing the structure of the angular position detection devices 8 and 10 in FIG. 1, FIG. An electric circuit diagram showing further details of the example, FIG. 4 is an operation diagram showing the output characteristics of the F-V circuit 25 of FIG. 3, and FIG. 5 is an operation waveform diagram explaining the operation of the embodiment of FIG. 1. , FIG. 6 shows the advance angle characteristics according to the embodiment shown in FIG. In the figure, 1 is a generator coil, 5 is an ignition coil, 6 is a spark plug, 7 is a thyristor, 8 and 10 are signal coils, 14 is a transistor, 15 is an ignition timing calculation circuit, 22 is a waveform shaping circuit, and 23 is a flip-flop circuit. , 24 is an arithmetic circuit;
25 is an F-V circuit, and 30 is a control circuit.

Claims (1)

[Claims] 1. A power supply device that generates positive and negative outputs in synchronization with the rotation of the engine and can energize the ignition coil with the rectified output; a switching element that controls the energization of the ignition coil; the first crank position corresponding to the predetermined crank position of
a first angular position detection device that is synchronized with the rotation of the engine and that corresponds to a crank position that is delayed by a predetermined angle from the generation position of the first angular signal; a second angular position detection device that has a wide angular width and generates a second angular signal that can be supplied to the opening/closing element; a second angular position detection device that starts calculation based on the first angular signal and calculates an ignition retard amount required by the engine; It includes an ignition timing calculation circuit and a control circuit that bypasses the second angle signal based on the signal obtained from the calculation result of the ignition timing calculation circuit, and controls only the retard characteristic portion of the required ignition timing characteristics of the engine. A magneto ignition device characterized in that the mutual crank positions of the first and second angle signal devices are determined so that the second angle signal is bypassed by a signal from an ignition timing calculation circuit.