JPS631007Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an improvement in an electronic ignition device for a magnet. Fig. 1 is a time chart showing the operating principle of the known example described in Japanese Patent Application Laid-Open No. 52-36234, and particularly shows the case where the engine rotational speed is drastically reduced, that is, the angular velocity ω is extremely reduced. This is what I did. In the time line a shown in FIG. 1, M ₁ and M ₂ indicate two different rotational angular positions of the crankshaft, T indicates top dead center, and S indicates the required ignition position. Further, the triangular waveform shown in the time line b is the voltage of the charging/discharging capacitor shown in the above-mentioned known example, Vref is the comparison voltage level that determines the above-mentioned charging start and discharging end time, and the above-mentioned capacitor is located at M It is set to be charged with a constant current i ₁ from position M _{1 to} position M 2, discharged with a constant current i ₂ after position M ₂ , and output an ignition signal at the comparison voltage level Vref.
Further, the curve shown by the time line c in FIG. 1 is a schematic representation of changes in the rotational angular velocity ω of the engine. In Fig. 1, the angle and elapsed time from position M ₁ to M ₂ are respectively θ ₁ and T ₁ , the angle and elapsed time from position M ₂ to position S are θ ₂ and T ₂ , and position S When calculating the advance angle α, assuming that α is the angle from position T to position T and θ ₃ is the angle from position T to the next position M ₁ , α = 180 − (θ ₁ + θ ₂ + θ ₃ ) [1], and θ ₁ , θ ₃ are both positions on the rotation angle of the crank
M ₁ and M ₂ are determined and constant, and θ ₂ is at time t ₂
If the average angular velocity from to t ₃ is ₂ , it is given by θ ₂ = ₂ T ₂ [2]. Therefore, α=K− ₂ T ₂ [3]. However, K exhibits a constant value as follows: K=180-θ ₁ -θ ₃ [4]. Next, since the amount of charge and discharge of the capacitor does not change, i ₁ T ₁ = i ₂ T ₂ [5] holds true, while T ₁ becomes T ₁ = θ ₁ /ω ₁ [6], and the above formula [3] ], [5], and [6], the advance angle α is shown as α=K−i ₁ /i ₂ ·ω ₂ /ω ₁ ·θ ₁ [7]. Therefore, if i ₁ or i ₂ is changed depending on the operating conditions of the engine, the advance angle α will change in accordance with the change. As described above, when trying to adjust the advance angle α based on equation [7], it is understood that ω ₂ /ω ₁ must always be constant. In this case, for example, if the engine's air-fuel mixture does not ignite when an ignition spark is generated at time _t7 , the rotational speed of the crank will decrease rapidly and it will take a long time to reach top dead center T and the next position _M1 . This means that the subsequent times T ₁ ′ and T ₂ ′, which approximately correspond to the ignition preparation periods of other cylinders, also become significantly longer. As a result, assuming that the average angular velocity from time t ₈ to t ₁₀ is ′ ₁ and the average angular velocity from time t ₁₀ to t ₁₁ is ′ ₂ , their ratio ′ ₂ /′ ₁ is smaller than the ratio ₂ / ₁ in the previous cycle. If the temperature increases, then from equation (7), even if i ₁ /i ₂ is constant, α will increase and the ignition spark will be generated at position S', which is gradually advanced from position S, which is the required ignition timing. . In general, the lower the speed of an engine, the worse the mixing condition of the intake air-fuel mixture, which tends to cause irregular combustion and ignition errors, and the larger the rotational fluctuations. Therefore, even if the charge/discharge current to the capacitor can be kept constant in order to fix the advance angle α constant in the low speed range of the engine, the angular velocity ω will change as shown in Figure 1.
If fluctuates widely every cycle, then
As _{the 2/1 ratio} changes from moment to moment, the actual ignition timing fluctuates around the required ignition timing S, and accurate and stable ignition timing can no longer be obtained. This invention solves the above-mentioned drawbacks and provides an excellent magneto ignition system that can stably retard the ignition position at low speeds in order to prevent the engine from getting stuck when starting the engine. An embodiment of this invention shown in the drawings will be described below. First, in one embodiment shown in FIGS. 2 to 6, reference numeral 1 denotes a power generating coil of a magneto (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 is a diode that rectifies the output of this generating coil; 3 is a capacitor that is charged by the output of the generating coil 1 rectified by this diode 2; 4 is an ignition coil connected to the discharge circuit of this capacitor 3; capacitor 3
The primary coil 4a and the spark plug 5 are connected in series.
The secondary coil 4b is connected to the secondary coil 4b. A diode 6 is connected in parallel to the primary coil 4a of the ignition coil 4. A thyristor 7 is a switching element provided in the discharge circuit of the capacitor 3, and when the thyristor 7 is conductive, the charge in the capacitor 3 is discharged to the primary coil 4a. 8 is a first signal coil for generating an ignition signal;
A first signal output having a relatively long electrical angle is generated at a required position of the engine in synchronization with the rotation of the engine. 9 is a second signal coil for detecting angular position;
A second signal output is generated corresponding to a predetermined crank position of the engine. The thyristor 7 is rendered conductive by one of these signals. 10 and 11 are diodes, 12 and 14 are resistors respectively connected to the gates of the thyristor 7, and 15 is an ignition timing whose calculation is started by the second signal output and which calculates the ignition timing according to the operating state of the engine. Regarding the arithmetic circuit, details of this circuit will be explained using FIG. In FIG. 3, reference numeral 19 denotes a waveform shaping circuit for shaping the signal output of the second signal coil 9, 191, 192, 1
93 is a resistor, 194 is a voltage comparator (hereinafter referred to as a comparator), 195 is a capacitor, 196 is a diode, 20 is a flip-flop circuit, 21 is an arithmetic circuit connected to this flip-flop circuit 20 and outputs a predetermined output according to the engine; 211,2
12 and 213 are resistors, 214 and 215 are diodes, 216 is a transistor, 217 is a capacitor, 218 is an operational amplifier (hereinafter referred to as an operational amplifier), 219 is a voltage comparator (hereinafter referred to as a comparator), and 22 is the above-mentioned second signal. This is a rotation speed-voltage conversion circuit (hereinafter referred to as an F-V circuit) that converts the shaped output of the output signal of the coil 9 into a DC voltage proportional to the rotation speed, which is taken as a rotation speed signal. One input terminal S of the flip-flop circuit 20 is connected to the waveform shaping circuit 19, and the other input terminal R is connected to the output of the comparator 219. In addition, the flip-flop circuit 20
One output terminal Q is connected to the base of the transistor 216 via a resistor 212 and to the emitter of the transistor 216 via a series circuit of a diode 215 and a resistor 213. The collector of the transistor 216 is connected to the output terminal of the F-V circuit 22 through the resistor 211 and the diode 219, and the emitter is connected to the inverting input terminal (hereinafter referred to as the (-) terminal) of the operational amplifier 218. . The output terminal of the operational amplifier 218 is connected to the (-) terminal of the comparator 219, and the capacitor 2
It is connected to its own (-) terminal via 17. And operational amplifier 218 and comparator 2
The non-inverting input terminal (+) of No. 19 is biased to the comparison voltage Vr ₁ . 23 is a pulse fall detection circuit that detects a predetermined output pulse according to the calculation result of the calculation circuit 21 and sends an output signal to the gate of the thyristor 7;
31 is a transistor whose base is a resistor 233
The collector is connected to one output terminal Q of the flip-flop circuit 20 through the resistor 232, the collector is connected to the power supply through the resistor 232, and the emitter is connected to ground. 234
is a capacitor connected to the collector of the transistor 231, and 235 is a discharge diode. FIG. 4 shows the output characteristics of the F-V circuit 22. Reference numeral 220 is an example of the characteristics, and the figure shows a case in which the output characteristics change linearly. Further, as shown in FIG. 4, this characteristic is set equal to the bias voltage Vr ₁ of the comparator 219 when the rotation speed is N ₁ . Next, in FIG. 5, time lines b to i are
The diagram shows the time charts of the voltages A to H at each part in the diagram, and the time line a in the diagram is a time chart that shows each number of the crank position, and M is the time chart that is higher than the maximum advance position required by the engine. S is the position at which the ignition device starts operating (Fig. 6 S).
position), and T indicates the top dead center as in FIG. The output voltage H of the first signal coil 8 that is output in response to the rotation of the engine is the first signal output that is the peak value of the waveform at the position S, as shown in FIG. Output voltage A is a signal output generated at position M as shown in FIG. Next, the operation of the above embodiment will be explained. First, the second
In the case of the CDI type magnetic ignition device shown in the figure, the rectified output of the power supply coil 1 causes the capacitor 3 to
is charged to the polarity shown, and the charged charge is applied to the ignition timing of the engine, that is, the output generation timing when the output voltage H of the first signal coil 8 is input, or the ignition when the output voltage A of the second signal coil 9 is input. Timing calculation circuit 1
5, the thyristor 7 is made conductive and applied to the primary coil 4a of the ignition coil 4, and a high voltage is generated in the secondary coil 4b, causing a spark to fly to the ignition plug 5. Next, the means for adjusting the conduction timing of the thyristor 7, that is, the ignition timing, will be explained in detail, including the advance angle characteristic diagram and FIG. 6. Now, suppose that the engine is rotating at a constant speed higher than the rotation speed N ₂ shown in Figure 6, and the ignition advance angle in that case is not zero but a position advanced by an angle α from the T position. The operations in FIGS. 2 and 3 are as follows. First, the F-V circuit 22 counts or integrates the output voltage corresponding to the engine rotation speed and outputs the output voltage 2.
20 is at a value higher than the bias voltage Vr ₁ . This output voltage 220 is the collector supply voltage of transistor 216. On the other hand, the flip-flop circuit 20 is set by the high level of the output voltage C at the position M,
Its output voltage E becomes high level. Output voltage E
When becomes high level, the transistor 216 is forward biased through the resistor 212 and is turned on. When the transistor 216 is turned on, the capacitor 217, which has been charged to the voltage polarity shown in FIG.
starts discharging at the current i ₂ shown in the equation below.

[Table] Value As can be seen from the above equation, the magnitude of this discharge current i ₂ depends on the output voltage 220 of the F-V circuit 22 if the bias voltage Vr ₁ and the resistance values of the resistors 211 and 212 are constant. . As the capacitor 217 starts discharging, the output voltage D of the operational amplifier 218 drops as shown in FIG. 5, and when it reaches the bias voltage Vr ₁ , a positive pulse voltage is generated at the output of the comparator 219, and this positive pulse voltage is reset. It becomes input. The flip-flop circuit 20 is reset when the above reset pulse is applied to its input terminal R, and its output voltage E becomes low level. The time width of the high-level output voltage E obtained as described above corresponds to the calculation result of the calculation circuit 21. Next, when the output voltage E of the flip-flop circuit 20 reaches a high level, the base current is supplied to the transistor 231 of the pulse fall detection circuit 23 via the resistor 233, so that the transistor 231 is turned on. Along with this, the electric charge of the capacitor 234, which had been charged to the polarity shown in the figure, is discharged through the transistor 231 and the diode 235, and the output voltage F becomes a low level. An output voltage of is generated. Next, when the output voltage E of the flip-flop circuit 20 reaches a low level from a high level, no base current is applied to the transistor 231, so the transistor 231 is turned off. charged in polarity. Along with this, the power supply terminal voltage F becomes high level, and the fifth
As shown in the figure, a large trigger voltage is generated and this trigger voltage is applied to the gate of the thyristor 7.
This position is a position that is further advanced than the above-mentioned position T by _α1 . Next, as described above, the flip-flop circuit 20 is
When the output voltage E of the transistor 216 becomes low level, the transistor 216 is cut off. Since the output voltage 220 of the F-V circuit 22 is no longer applied to the inverting input terminal (-) of the operational amplifier 218 due to the cut-off of the transistor 216, the output voltage D of the operational amplifier 218 starts to rise. As a result, the capacitor 217 generates a current i ₁ shown in the following equation in the polarity direction shown in the figure.
Start charging. i ₁ = Vr ₁ - Voltage drop of diode 215/resistance 213
resistance value of

[9] As can be seen from the above equation, the magnitude of this charging current i ₁ is a constant value regardless of the rotation speed. Therefore,
The charging voltage of the capacitor 217, ie, the output voltage D of the operational amplifier 218, has a linear waveform with a constant slope regardless of the rotation speed, as shown in FIG. Next, when the output voltage B becomes high level again at position M in the range of rotational speeds lower than _N2 and higher than _N1 shown in FIG. After discharging, the output voltage E of the arithmetic circuit 21 becomes high level, but the output voltage 220 of the F-V circuit 22 is lower than the value of the previous cycle, and from equation (8), the discharge current i ₂ The size is getting smaller. Therefore, it takes more time for the voltage of the capacitor 217, that is, the output voltage D of the operational amplifier 218, to reach the bias voltage Vr ₁ than in the previous cycle, and as shown in FIG. The bias voltage Vr ₁ is reached at a delayed position, that is, a position α ₂ ahead of the top dead center T, and the output voltage E drops to a low level. When the output voltage E of the flip-flop circuit 20 becomes a low level, the output voltage F shifts to a high level, so the output G becomes a trigger pulse at a position later than the set position S and is activated by the thyristor 7, as shown in FIG. Supplied to the gate. This position is an angle α ₂ ahead of the top dead center T. Next, when the output voltage B becomes high level again at position M in a region lower than the rotational speed _N1 shown in FIG. 6, the flip-flop circuit 20 is set and the capacitor 217 is discharged in the same manner as described above. At this time, as can be seen from FIG. 4, the output voltage 220 of the F-V circuit 22 is lower than the bias voltage Vr ₁ , so
Even though transistor 216 is turned on,
The output voltage 220 of the F-V circuit 22 is equal to the discharge current i ₂
The discharge current i ₂ that does not contribute to is as shown in the equation below.

[Table] As can be seen from the above equation, in this region, the discharge current
The magnitude of i ₂ is a constant value regardless of the rotation speed.
In addition, since both the charging current and _i1 are constant values regardless of the rotational speed as described above, in this region, the output voltage E of the flip-flop circuit 20 is at a low level, that is, the trigger pulse supplied to the gate of the thyristor 7. The position is always a certain angle ahead of the top dead center T. With the above operation, if only the output of the ignition timing calculation circuit 15 is supplied to the gate of the thyristor 7, the advance angle characteristic will be 3 as shown by the solid line as shown in FIG.
01 can be obtained. Also, when only the output H of the first signal coil 8 is supplied to the gate of the thyristor 7, the signal output has a long electrical angle, so at very low speeds it is triggered at the peak position S of the signal output, but the trigger of the thyristor 7 Since the level is constant, as the engine speed increases, the signal output grows and is triggered before the peak position. Therefore, the advance angle characteristic 302 shown by the broken line in FIG. 6 is obtained. Here, when the output voltage due to the output H of the first signal coil 8 and the output voltage G calculated based on the output A of the second signal coil 6 are continuously applied to the gate of the thyristor 7, as shown in FIGS. By setting the angular relationship shown in the figure, the signal voltage (G or H) applied to the gate of the thyristor 7 first causes the charge in the capacitor 3 to be transferred to the ignition primary coil 4.
a, which induces a high voltage in the ignition secondary coil 4a and causes the spark plug 5 to emit a spark.
Therefore, even if the later signal (G or H) is supplied to the gate of the thyristor 7 and the thyristor 7 is turned on, the capacitor 3 has already been discharged and has no charge, so there is no high voltage applied to the ignition coil 4. Not induced. That is, in an area where the rotational speed is higher than _N2 in FIG. 6, ignition occurs at a position indicated by a solid line 301 in FIG. 6, and in an area where the rotational speed is lower than _N2 , ignition occurs at a position indicated by a broken line 302 in FIG. A case will be described in which the air-fuel mixture in the engine fails to ignite for some reason after the engine operates as described above and ignites at a rotation speed of N2 or _less in FIG. 6 as indicated by the broken line 302. Such misfires are particularly likely to occur when the engine speed is low and are caused by variations in the mixture ratio of the air-fuel mixture. If a misfire occurs for the reasons mentioned above, the rotational angular velocity of the crank will decrease rapidly, and the time it takes to reach the next position M will be significantly longer. However, capacitor 2
Since the charging current i ₁ to the operational amplifier 17 is constant as shown in equation (9), the charging voltage D, that is, the operational amplifier 218
The output voltage D of is increased compared to the previous cycle. In this way, after a misfire, when the output voltage B becomes high level at the next position M, the flip-flop circuit 20 is set as before, and the capacitor 2
17 turns into a discharge state. Assuming that the output voltage D reaches the bias voltage _{Vr 1 at a position α 2 advanced} from the top dead center T after being discharged with the discharge current i 2 , the output voltage E drops to a low level at this point. However, the output voltage F becomes high level, and accordingly, the output voltage G becomes a large trigger pulse and makes the thyristor 7 conductive. However, earlier than the time at which this trigger pulse is generated, the output H of the first signal coil 8 is supplied to the gate of the thyristor 7, causing the charge charged in the capacitor 3 to be applied to the ignition coil 4, causing the secondary coil 4b to ignite. generate voltage,
Make sparks fly from spark plug 5. Therefore, even if the trigger pulse is applied to the thyristor 7, the capacitor 3
Since no charge is accumulated in the ignition coil 4, no ignition voltage is generated in the ignition coil 4, and no spark is produced in the ignition plug 5. As described above, first of all, when the engine is rotating at a rotation speed higher than the rotation speed _N2 , the calculation result of the calculation circuit 21 which receives the output voltage A of the second signal coil 9 as input, that is, the fall of the output voltage E. ignite at the engine point, and explain that this ignition timing IG is at least a position that is advanced beyond the zero advance angle position S required by the engine.Next, with the rotation speed dropping below N ₂ ,
If the rotation is maintained, even if a misfire occurs for some reason, ignition is performed by the output signal H, which is the retarded side of the first signal coil 8, regardless of the calculation result of the calculation circuit 21, as shown in FIG. I explained how to obtain lead angle characteristics like this. In other words, at low speeds where engine rotational fluctuations or angular velocity changes vary widely over each cycle,
It is intended to ignite using a first signal output made up of an extremely simple circuit, regardless of the result of electrical calculation. Although the CDI type magnetic ignition device has been described above, the present invention can also be applied to a current interrupt type magnetic ignition device as shown in FIG. That is, in FIG. 7, 24 is a power supply coil;
It also serves as the primary ignition coil. 25 is an ignition secondary coil, 26 is a thyristor connected in series to the power supply coil via a resistor 27, and the gate of this thyristor 26 is connected to the output of the first signal coil 8 and the output of the second signal coil 9. Each output is register 12
and is connected via an ignition timing calculation circuit 15. 28 is a transistor whose base is connected to the connection point between the resistor 27 and the anode of the thyristor 27, whose collector is connected to one end of the power supply coil 24, and whose emitter is connected to the other end of the power supply coil 24;
29 has a cathode at one end of the power supply coil 24;
The anodes are diodes each connected to the other end of the power supply coil 24. In this embodiment, the power coil 24
Due to the output in the _B1 direction, a base current flows through the transistor 28 via the resistor 27, so the transistor 28 becomes conductive, and therefore a large current flows through the power supply coil. Thereafter, when the ignition timing of the engine comes, the output of the first signal coil 8 and the calculation output of the second signal coil 9 are applied directly to the gate of the thyristor 26, and the thyristor 26 becomes conductive. Along with this, the current flowing through the power supply coil 24 rapidly decreases, and a high voltage is induced in the ignition secondary coil 25 in accordance with the current change, causing the spark plug 5 to spark. Further, since the output of the power supply coil 24 in the A direction is short-circuited by the diode 29, it does not contribute to ignition. By the way, in the case of this embodiment, as in the above embodiment, when the engine rotation speed is _N2 rotations or more, the calculated output of the output of the second signal coil 9 is faster, and
At _N2 rotations or less, the output of the first signal coil 8 is applied to the thyristor 26 earlier and contributes to ignition.
Moreover, the thyristor 26
Conduction signals are continuously applied to the thyristor 26, but since the first signal causes the current flowing through the power coil 24 to decrease, even if a later signal is applied to the thyristor 26, the current flowing through the power coil 24 does not continue. No change occurs in the current, and therefore no ignition voltage is generated in the ignition secondary coil 25. As described above, this invention consists of a first signal coil 8 that generates an ignition signal at a required ignition position when the engine is running at low speeds, and a first signal coil 8 that operates an arithmetic circuit that generates an ignition signal at a required ignition position at high speeds. The output of the first signal coil 8 and the output obtained by operating the ignition timing calculation circuit using the output of the second signal coil 9 are both sent to the control pole of the switching element. The output of the first signal coil 8 is used as the ignition signal especially when starting the engine and in a low speed range with large rotational fluctuations, and the output of the ignition timing calculation circuit is Since the ignition signal is obtained as an ignition signal, there is no fluctuation in ignition timing caused by severe rotational fluctuations during startup and at low speeds, which was seen in conventional devices, and it is possible to obtain accurate and stable ignition timing. can. In addition, since the ignition timing is determined by the ignition timing calculation circuit in the high-speed rotation range, the second signal coil 9 may be a simple one that generates an angular position signal. Since it is directly supplied to the control electrode of the control electrode, there is no need for a circuit for selecting two outputs, and the device can be constructed at low cost. In addition, since the ignition signal is formed through calculation, there is little variation in ignition timing, and the ignition timing does not change due to temperature, making it possible to obtain advanced angle characteristics over a wide range with high precision. It has the effect of becoming a magnetic ignition device. Furthermore, since the two signals are input to the same input terminal of the same switching element, there is no need for a selection circuit for selecting the two signals, simplifying the circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is an operational waveform diagram explaining the operation of the conventional device, FIG. 2 is an electric circuit diagram showing an embodiment of this invention, FIG. 3 is an electric circuit diagram showing further details of the embodiment of FIG. 4 is an operation diagram showing the output characteristics of the F-V circuit in FIG. 3, FIG. 5 is an operation waveform diagram explaining the operation of the embodiment in FIG. FIG. 7 is an electric circuit diagram showing another embodiment of the present invention. In the figure, 1 is a generator coil, 4 is an ignition coil, 5 is a spark plug, 7 is a thyristor, 8 and 9 are signal coils, 15 is an ignition timing calculation circuit, 19 is a waveform shaping circuit, 20 is a flip-flop circuit, and 21 is a calculation 22 is an F-V circuit, 23 is a pulse fall detection circuit, and 24 is a power supply coil. Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] 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;
An ignition switching element that controls energization to the ignition coil, which is synchronized with the rotation of the engine, corresponds to a predetermined crank position of the engine, and has an electrical angle whose waveform grows as the engine speed increases. a first signal generator having a signal coil that generates a wide first angle signal; a second signal generating device that generates an angle signal; and a second signal generating device that is determined according to at least the rotational speed of the engine based on the angle signal of the second signal generating device, and that at a predetermined rotational speed of the engine, the The first signal generating device includes an ignition timing calculation circuit that calculates an ignition timing that coincides with the generation position of the first angle signal and that advances as the rotational speed increases to form an ignition signal. The output end of the first angle signal and the output end of the ignition signal in the ignition timing calculation circuit are connected to the control electrode of the ignition switching element, and the ignition switching element is driven by the earlier signal. If the rotation speed of the engine is lower than the predetermined rotation speed, the first angle signal from the first signal generator causes the ignition timing to be ignited by the ignition timing calculation circuit. A magneto ignition device characterized by being ignited by a signal.