JPH0711270B2 - Capacitor charge / discharge ignition device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a capacitor charging / discharging type ignition device, and more particularly to prevention of ketching of a two-cycle engine used in a motorcycle or the like.

(Prior art and its problems) In a motorcycle using a two-cycle engine,
As is well known, it is common to rotate a crankshaft by a stepping kick to start the crankshaft. However, generally in a two-cycle engine, so-called ketching, which is not easy to start by kicking, is likely to occur.

In order to prevent this, as is well known, the position where the ignition device is largely moved in the rotation direction (the direction of the arrow in the drawing) from the top dead center (a) of the engine as shown in FIG. 1, a so-called large retard position θ ₂
Is effective. On the other hand, however, during steady rotation, it is desirable to set the ignition position close to the top dead center (a), that is, the small retard position θ ₁ as shown in FIG. Further, in order to prevent the torque from decreasing when the rotational speed exceeds a certain value, it is desirable to retard the rotational speed as the rotational speed increases.

However, in the conventional ignition device, if the ignition position is set to a large retard angle at the time of starting, the ignition after the starting is also performed at the large retard position. For example, the capacitor charging / discharging type ignition device that has been used most often these days, that is, the capacitor is charged by the power generation coil output that is rotated by the engine, and this is used as the negative pulse output from the timing pulse generation coil, that is, the change in the rotation speed. Correspondingly, a negative timing pulse whose generation position changes with respect to the reference positive timing pulse is used to ignite the discharge thyristor, thereby discharging the charge stored in the capacitor to obtain ignition energy. When the engine and the timing pulse generating coil are related to each other so as to obtain the retard angle, the generation position of the negative timing pulse after starting is also relatively displaced in the retard direction. Therefore, in the conventional ignition device, the ignition position is actually adjusted after starting, and it is difficult to simultaneously satisfy both requirements of preventing ketching and realizing good steady operation characteristics.

(Object of the Invention) The present invention provides a capacitor charging / discharging ignition device capable of satisfying the above-mentioned requirements, and a capacitor charging / discharging ignition device excellent in stability of ignition operation such as obtaining a constant and large ignition energy. It also aims to improve the operating characteristics of the two-cycle engine in addition to the advantages of.

(Means of the Present Invention for Solving Problems) The present invention is most suitable for starting the ignition position when the position of the negative timing pulse of the capacitor charging / discharging type ignition device is within a set starting speed range. In a state of retarded angle,
When the negative timing pulse detects that the engine speed has exceeded the set speed range N ₁ at the time of starting,
The ignition position is automatically and rapidly advanced (stepwise) in the direction of the top dead center so that the ignition position required for steady operation can be obtained, and good steady operation characteristics can be obtained while preventing ketching. It is something that can be obtained.

Next, the present invention will be described in detail with reference to examples.

(Structure of Embodiment) FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIGS. 3, 4, and 5 are waveform diagrams of respective portions of the circuit. In the figure, I is an ignition circuit, which is formed from the following parts. EXT is an AC power generation coil, which generates power by rotating the engine. D ₁ is a short-circuit diode, which short-circuits the negative voltage of the output voltage of the AC generating coil EXT to obtain only the positive voltage. D ₃ is a reverse current blocking diode, C ₁ is a capacitor for acquiring ignition energy, IGN is an ignition coil, PG is a spark plug, SCR is a discharge thyristor, and capacitor C ₁
Is a circuit of [EXT → D ₃ → ING primary winding N ₁ → EXT], and the generator coil is charged by the positive voltage from EXT. In addition, the discharge thyristor SCR is discharged in the circuit during ignition [C ₁ → SCR → IGN → C ₁ ], which causes a high voltage in the secondary winding N ₂ of the ignition coil IGN to ignite the plug PG. ,
Further, a known operation of turning off the discharge thyristor is performed.

II is a control power supply circuit, which is formed of the following parts. D ₂ is a polarity selection diode, R ₁ is a resistor, D ₂ is a constant voltage element such as a Wenner diode, C ₂ is a power supply capacitor, and the capacitor C ₂ is a diode from the generator coil EXT selected by the diode D ₂ . Constant voltage element D ₂
Is charged to a constant voltage determined by. The operation power supply of the ignition control circuit III, which is the main part of the present invention described below, is made from its own circuit without using a separate power supply, and of course a separate power supply is also used.

Reference numeral III denotes an ignition control circuit which is a main part of the present invention, and includes a discharge thyristor SCR of the ignition circuit I, a trigger circuit A of a step advance angle frequency setting circuit, a differential circuit B, and a step advance angle rotational speed setting circuit, which will be described later. C, each of which is formed from the following parts:

In the trigger circuit A, PC is a timing pulse generating coil, and as shown in FIG. 3 (a), the time between the reference positive timing pulse P and the positive timing pulse P corresponding to the engine speed per engine revolution. It is mounted on the engine so as to generate a negative timing pulse P with varying intervals t and obtain the required ignition position. Further, the time width t ₁ of the negative timing pulse is selected corresponding to the required stepwise advance width of the ignition position. R ₂ is a resistor, D ₅ is a polarity selection diode, Q ₂ and Q ₁ are switching transistors, D ₄
Is a reverse current blocking diode, C ₃ is a capacitor for the ignition power supply of the discharging thyristor SCR, and C ₃ is a transistor for turning on when a negative timing pulse P is generated, via transistors Q ₂ and Q ₁ and a diode D _4. As shown in FIG. 3 (b), the power supply circuit for control II is charged by the positive voltage output.

IC ₂ is an AND circuit, IC ₅ is a NOR circuit, D ₇ is a polarity selection diode, R ₉ is a resistor, Q ₆ is a discharge thyristor SCR.
A arc control switching transistor points, Q ₆ is
When the output signal level of IC ₅ is "L", it is turned on, the gate current is made to flow from the capacitor C ₃ to the discharging thyristor SCR and it is ignited, thereby discharging the charge of the capacitor C ₁ and Fig. 3 Ignition is performed as shown in (h). D ₆ is a polarity selection diode, and Q ₃ is a control transistor of the step advance rotation speed setting circuit C described later.

In the differentiating circuit B, IC ₁ is a buffer circuit, C ₄ is a capacitor, R ₈ is a resistor, D ₈ is a short-circuit diode, and the transistor is turned on by a negative timing pulse P.
The negative timing pulse P input via Q ₂ is differentiated, and the unnecessary negative polarity portion of D ₈ is short-circuited to generate the end position signal of the negative timing pulse P shown in FIG. Add to NOR circuit IC ₅ .

In the step advance angle rotation speed setting circuit C, R ₄ and R ₅ are resistors, Q ₄ and Q ₅ are switching transistors, C ₅ and C ₆ are capacitors of the same capacity, R ₆ and R ₇ are discharging resistors, and IC ₃ Is an inverter circuit, IC ₄ is an AND circuit, and these are capacitors C
_{It has} threshold values l ₁ and l ₂ that are 1/2 of the maximum level when charging ₅ and C ₆ , respectively. The transistors Q ₄ and Q ₅ are turned on when the transistor Q ₃ of the trigger circuit A is turned on by the positive timing pulse P, and the capacitors C ₅ and C ₆ are turned on by the output voltage of the control power source II. The battery is charged to a constant voltage only during the sending period of the positive timing pulse P. When the delivery of the positive timing pulse P is stopped, the capacitor C ₅ via a resistor R _6, R _7,
The electric charges of C ₆ are discharged respectively. Here, the respective discharge time constants are related to the threshold levels of the inverter circuit IC ₃ and the AND circuit IC ₄ of the trigger circuit A as follows. And the step advancing rotation number N ₁ shown in FIGS. 3 (c) and 3 (d) is set.

That is, when the timing pulse generating coil PC and the engine are placed in a relational position so that the negative timing pulse P is generated at the optimum retard position at the time of startup, the capacitor C ₅ as shown in FIGS. , C _{6 The} discharge voltage level is set to be lower than the threshold levels l ₁ and l ₂ of the inverter circuit IC ₃ and the AND circuit IC ₄ . Further, when the engine starts and reaches a certain number of revolutions, the discharge level of the capacitor C ₅ is changed to the inverter circuit IC _{3 at the} position where the negative timing pulse P is generated as shown in FIGS. 4 (c) and (d).
The shredding hold level lower than the l _1, capacitor
Set the discharge time constant so that the discharge level of C ₆ exceeds the threshold level l ₂ of the AND circuit IC ₄ . The discharge voltage of the capacitors C ₅ and C ₆ is applied to the AND circuit IC ₄ , and the output signal thereof is applied to the AND circuit IC ₂ to which the output voltage of the control power supply circuit II is applied to one terminal.
Further, the output signal of the differentiating circuit B is added to one terminal of the output signal of the IC ₂ . It is added to the NOR circuit IC ₅ , and its output signal is the ignition control transistor Q of the discharge thyristor SCR.
Control on / off of ₆ .

Next, the operation will be described step by step with reference to FIG. 2, FIG. 3, FIG. 4, FIG. 5 and FIG.

(Operation at Startup (Low Speed Rotation)) As shown in FIG. 3 (a), the positive timing pulse P is the coil.
When it is sent from the PC, it turns on the transistor Q ₃ via the diode (6), which causes the transistors Q ₄ and Q
_{When 5} is turned on, the capacitors C ₅ and C ₆ are charged to the charging voltage of the capacitor C ₂ of the control power supply circuit II as shown in FIGS. When the transmission of the positive timing pulse P is stopped, the electric charges of the capacitors C ₅ and C ₆ are discharged with a constant time constant determined by the resistors R ₆ and R ₇ . The voltage of this capacitor C ₅ passes through the inverter circuit IC ₃ and the AND circuit I
The voltage of the capacitor C ₆ is input to one terminal of C ₄ , and the voltage of the capacitor C ₆ is input to the other terminal of the AND circuit IC ₄ , where the voltage of C ₅ and C ₆ is the threshold level of IC ₃ and IC _4. When it is above, the input level of IC ₄ becomes "L" and "H", and its output level becomes "L" level. Also at this time AND circuit IC ₂
Since the input level of one is "L", its output level is "L", and the differentiation circuit B that enters one terminal of the NOR circuit IC ₅
The output level of is "L" because there is no transmission of the negative timing pulse P, and therefore its output level is "H". Therefore, while the discharge level of the capacitors C ₅ and C ₆ is lower than the threshold level of IC ₃ and IC ₄ , the transistor Q ₆ is in the off state and the discharge thyristor SCR does not discharge the capacitor C ₁ and the plug The PG is not ignited.

Next, when the negative timing pulse P is sent out as shown in FIG. 3 (a), the transistors Q ₂ and Q ₁ are turned on, and the capacitor C ₂ of the control power supply circuit II as shown in FIG. 3 (b). The thyristor SCR for discharge is charged to the charging voltage of and the power supply for igniting the gate of the SCR is made, and at the same time, the input is applied to the AND circuit IC ₂ . On the other hand, when Q ₂ is turned on, NOR circuit IC ₅ is shown in FIG. 3 (e).
A signal indicating the end position of the negative timing pulse is input from the differentiating circuit B shown in FIG. 2, but as described above, the capacitors C ₅ and C ₆ at the time of sending the negative timing pulse P are input.
The discharge voltage level of is set below the threshold level of the inverter IC ₃ and the AND circuit IC ₄ .

Therefore, the input level of the AND circuit IC ₄ becomes “H” and “L”, the output level thereof becomes “L”, and the input level of the AND circuit IC ₂ becomes “L” and “H”, so that the output level thereof becomes the first level. It becomes "L" as shown in Fig. 3 (f). The input level of NOR circuit IC ₅ becomes "L" and "H", and its output level is shown in Fig. 3 (g).
As described above, the differential signal width from the differentiating circuit B (see FIG. 3 (e)) changes from "H" to "L". Therefore, the transistor Q ₆ of the trigger circuit A is turned on only when the differential input is applied, and the gate charge is made to flow through the discharging thyristor SCR by the charge stored in the capacitor C ₃ , which causes the charge in the capacitor C ₁ to be discharged, and FIG. The ignition of the plug PG is performed at the terminal position θ ₂ of the negative timing pulse P as shown in (h). Therefore, if the ignition position is set to the optimum point for starting, good starting is performed.

(Operation after startup) The engine speed increases due to startup, the time interval t between the reference positive timing pulse P and the negative timing pulse P becomes short as shown in FIG. 4 (a), and the negative timing pulse P
Exceeds the advance rotation speed set point N ₁ , the discharge voltage level of the capacitor C ₅ , and hence the input level of the inverter circuit IC ₃ is “L”, while the discharge voltage level of the capacitor C ₆ and therefore the output of IC ₄ level is "L", and the input level of the aND circuit IC ₂ includes the "H""L", the output level only delivery period of the negative timing pulse P as in the fourth diagram (f) "H". Therefore, the output level of NOR circuit IC ₅ is shown in Fig. 4 (g).
Negative by timing pulse period of the sum of the delivery period and the signal sending time of the differentiation circuit B which follow the P becomes "L" level as to turn on between the transistor Q ₆ saw. Therefore, the capacitor C ₃ causes a gate current to flow into the discharging thyristor SCR to ignite it, and the discharge of the capacitor C ₁ by this causes ignition of the plug PG at an angle θ ₁ as shown in FIG. 4 (h). Be seen. In this state, the discharge voltage levels of capacitors C ₅ and C ₆ are both inverter circuit IC ₃ and AND circuit I.
It continues until the rotation speed set point N ₂ at which the threshold level of C ₄ becomes l ₁ , l ₂ or more, and the negative timing pulse P
Changes depending on the rotation speed, so the ignition position θ ₁ is constant up to the rotation speed set point N ₂ .

That is, according to the present invention, the ignition position after starting is automatically and rapidly advanced in the direction of the top dead center by the negative timing pulse width than that at the time of starting, and the relationship shown in FIG. 6 is obtained.

When the number of revolutions further rises and the generation point of the negative timing pulse P exceeds N ₂ , the discharge voltage level of the capacitors C ₅ and C ₆ at the transmission point of the negative timing pulse P becomes as shown in FIG. ), Both exceed the threshold levels l ₁ and l ₂ of the inverter circuit IC ₃ and the AND circuit IC ₄ .
Therefore, the output level of IC ₄ is “L”, that of the AND circuit IC ₂ is “H”, that of the NOR circuit IC ₅ is “L”, and the transistor Q ₆ is not turned on at the sending point of the negative timing pulse P. Ignition is not performed because it is not performed. However, since the capacitor C ₃ is charged by the positive timing pulse P, the output level is "H" at the switching point when the discharge voltage level of the capacitor C ₅ is not less than the threshold level l _{1 of the} inverter circuit IC ₃ or more. NOR circuit I
The output of C ₅ turns on the transistor Q _6, and the electric charge of the capacitor C ₃ causes an ignition current to flow through the gate of the discharging thyristor SCR to ignite as shown in FIG. 5 (h). Moreover, this switching point is gradually moved away from the sending position of the negative timing pulse P as the rotation speed increases, so that the ignition position also returns in the retard direction, that is, the direction of θ ₂ as shown in FIG. 6, as the rotation speed increases. Therefore, the operation is performed while automatically preventing the decrease in the torque due to the decrease in the rotation speed.

(Effects of the Invention) As described above, according to the present invention, the optimum ignition position for operation can be automatically given at the time of startup and after startup.
The thyristor engine can have good starting characteristics and driving characteristics, and driving performance of a device such as a motorcycle or a small boat that uses a two-cycle engine can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of a desirable ignition position of a two-cycle engine, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIGS.
FIG. 6 is a waveform diagram for explaining the operation, and FIG. 6 is a relationship diagram between the rotation speed and the ignition timing obtained by the present invention.

Claims (1)

[Claims] 1. A capacitor charging / discharging ignition device, wherein each of the first and second parts is charged by a positive timing pulse sending width from its timing pulse generating coil and discharged at different time constants after the positive timing pulse sending is stopped. A lead angle rotation speed setting circuit that makes an output of L level at startup and H level after startup by comparing the discharge voltage level of the capacitor with the reference level respectively, and the advance angle at the time of sending out a negative timing pulse from the timing pulse generating coil. From the rotation speed setting circuit output and the differential output of the negative timing pulse output and the negative timing pulse output, when the output of the advance angle rotation speed setting circuit is at the L level, only the negative timing pulse output width of the capacitor charge / discharge type ignition circuit is obtained. The ON signal of the charging / discharging capacitor discharging switching element is sent, and the advance angle rotation speed setting circuit When the force is at the H level, a trigger circuit is provided which sends out an ON signal of the charging / discharging capacitor discharging switching element of the capacitor charging / discharging ignition circuit by the sum of the negative timing pulse width and the time width of the differential output of the negative timing pulse. A capacitor charging / discharging type ignition device characterized in that the ignition position is advanced toward the top dead center by the negative negative timing pulse width.