JP3609668B2 - Capacitor charge / discharge ignition system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a capacitor charge / discharge igniter used for a two-cycle engine or the like.
[0002]
[Prior art]
In a capacitor charging / discharging ignition device used for a brush cutter, other small two-cycle engines, etc., as described in JP-A-8-86263, it is induced in a power generation coil when the rotor is rotated. Using the main direction induced voltage and the reverse direction induced voltage, the main direction induced voltage charges the charge / discharge capacitor, the reverse direction induced voltage makes the switching element conductive, and the charge of the charge / discharge capacitor is ignited through this switching element. The coil is discharged and a high voltage is generated by the ignition coil to ignite.
[0003]
In this ignition device, it is necessary to prevent over-rotation of the engine, improve safety, extend the life of engine components, reduce vibration, and the like. A rotation speed detection circuit that detects the rotation speed of the engine from the induced voltage and a trigger circuit that triggers the switching element based on the detection output thereof, detects the rotation speed of the engine and controls the trigger timing of the switching element, The ignition timing is delayed at the time of overspeed.
[0004]
[Problems to be solved by the invention]
Since the conventional trigger coil, rotation speed detection circuit and trigger circuit are provided and the ignition timing is controlled by these, the configuration is complicated, the number of parts is increased, the manufacturing cost is increased, and the entire apparatus is There is also a problem of increasing the size.
[0005]
In view of such conventional problems, the present invention is a capacitor charging / discharging ignition device that can be easily and inexpensively manufactured with a simple circuit configuration, can be downsized as a whole, and can easily set a retard start and a retard width. The purpose is to provide.
[0006]
[Means for Solving the Problems]
In the present invention, the charging / discharging capacitor 2 is charged by the main-direction induced voltage A of the power generation coil 1, and the switching element 8 is made conductive when the drive voltage due to the reverse direction induction voltage B of the power generation coil 1 rises to a predetermined voltage. In the capacitor charge / discharge type ignition device configured to discharge the charge of the charge / discharge capacitor 2 to the ignition coil 4, the main direction induced voltage A and the drive voltage of the switching element 8 are applied to the drive circuit 9 of the switching element 8. And a retard circuit 13 that delays the ignition timing by reducing the drive voltage of the switching element 8 when the difference between the two is equal to or greater than a predetermined value.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0008]
The drawings illustrate one embodiment of the invention. In FIG. 1, reference numeral 1 denotes a power generation coil, which is provided on a fixed iron core or the like. By rotating a rotor provided with a magnet, a main direction induced voltage A and a reverse direction induced voltage B (see FIGS. 2 and 3) are sequentially applied. Induces.
[0009]
A charging / discharging capacitor 2 is charged by a main circuit induced voltage A of the generator coil 1 through a charging circuit such as a rectifier diode 3, a charging / discharging capacitor 2, a primary coil 5 of an ignition coil 4 and the like. It has become. The ignition coil 4 includes a primary coil 5 and a secondary coil 6, and a high voltage is generated in the secondary coil 6 when the discharge current of the charge / discharge capacitor 2 flows through the primary coil 5. It is like that. A spark plug 7 is connected to the secondary coil 6 of the ignition coil 4.
[0010]
Reference numeral 8 denotes an SCR constituting a discharge switching element, which is connected in series to a discharge circuit including a charge / discharge capacitor 2 and a primary coil 5 of the ignition coil 4. The SCR 8 becomes conductive when a predetermined drive voltage due to the reverse induced voltage B 1 of the generator coil 1 is applied to the drive terminal (trigger terminal) via the voltage dividing resistors 10 and 11 of the drive circuit 9. The charge of the discharge capacitor 2 is discharged through the primary side coil 5 of the ignition coil 4.
[0011]
The drive circuit 9 of the SCR 8 is for applying a drive voltage based on the reverse induced voltage B 1 of the power generating coil 1 to the drive terminal of the SCR 8 and includes resistors 10 to 12 for dividing the reverse induced voltage B 1 of the power generating coil 1. In addition to being interposed between the winding start end of the power generation coil 1 and the drive terminal of the SCR 8, a retard circuit 13 is connected to the drive circuit 9. Note that the drive terminal of the SCR 8 is connected between the resistor 11 and the resistor 12.
[0012]
The retarding circuit 13 compares the main direction induced voltage A and the driving voltage of the SCR8, and delays the ignition timing by reducing the driving voltage of the SCR8 when the difference between the two is more than a predetermined value. is there. The retard circuit 13 includes a retard control capacitor 14, a rectifier diode 15, a Zener diode 16, a discharge resistor 17, a charge resistor 18, and the like.
[0013]
The retard control capacitor 14 and the rectifier diode 15 are for constituting a first charging circuit including the power generation coil 1, the charge / discharge capacitor 2, and the primary coil 5 of the ignition coil 4. It is connected in series to the end side, and is charged in the direction opposite to the drive voltage of the SCR 8 by the main direction induced voltage A 1 of the generator coil 1.
[0014]
The discharge resistor 17 is used for setting the retard start speed, and the charge / discharge amount of the retard control capacitor 14 is adjusted by the time constant between the discharge resistor 17 and the retard control capacitor 14 to start the retard start. The engine speed and retard angle range are set. Note that a variable resistor is used as the discharge resistor 17 and is connected between both ends of the retardation control capacitor 14.
[0015]
The Zener diode 16 and the charging resistor 18 are connected in series between the connection point between the retardation control capacitor 14 and the rectifier diode 15 and the connection point between the voltage dividing resistors 10 and 11. The Zener diode 16 constitutes a second charging circuit together with the generator coil 1, resistors 10 and 18, the retard control capacitor 14, and the rectifier diode 19, and the drive voltage of the drive terminal of the SCR 8 and the retard control capacitor 14 When the difference from the charging voltage becomes equal to or higher than the Zener voltage V _Z , the retard control capacitor 14 is charged in the direction opposite to the charging direction by the main direction induced voltage A, and the driving voltage of the driving terminal of the SCR 8 is set. It is supposed to decrease. In other words, the Zener diode 16 compares the main-direction induced voltage A and the reverse-direction induced voltage B of the generator coil 1 and is turned on when the difference between the two is equal to or higher than the predetermined Zener voltage V _Z , thereby driving the SCR 8. The ignition timing is delayed by reducing the voltage.
[0016]
The reverse induced voltage induced following the main direction induced voltage A 1 of the generator coil 1 is erased by reverse wave processing means (not shown).
[0017]
Next, the operation of this ignition device will be described with reference to the waveform diagrams of FIGS. 2 is a voltage waveform diagram when the retard circuit 13 is not activated, and FIG. 3 is a voltage waveform diagram when the retard circuit 13 is activated. As shown in FIGS. 2 and 3, the main direction induced voltage A 1 is induced on the winding end end side of the power generating coil 1, and the reverse direction induced voltage B 2 is induced on the winding start end side of the power generating coil 1. 2 and 3 indicate the voltage at the connection point between the resistor 10 and the resistor 11, that is, the driving voltage of the driving circuit 9 of the SCR 8, and D indicates the charging voltage on the anti-ground side of the retard control capacitor 14, respectively. when the sum of the charging voltage D and the driving voltage C is equal to or greater than the Zener voltage V _Z, zener diode 16 conducts.
[0018]
When the rotor is rotated at the time of starting, as shown in FIG. 2, a main direction induced voltage A 1 and a reverse direction induced voltage B 1 are induced in the power generating coil 1. When the main-direction induced voltage A 1 is induced, the charge / discharge capacitor 3 passes through the charge circuit of the rectifier diode 3, the charge / discharge capacitor 2, the primary coil 5 of the ignition coil 4, the retard control capacitor 14, and the rectifier diode 15. 2 and the retardation control capacitor 14 are charged by the main direction induced voltage A 1.
[0019]
After charging / discharging capacitor 2 is charged by main direction induced voltage A 1, reverse direction induced voltage B 1 is induced in power generating coil 1. Then, the reverse induced voltage B is applied to the driving terminal of SCR8 through the resistor 10, 11 of the drive circuit 9, if the drive voltage is a predetermined trigger level, as shown in FIG. 2, the time T ₁ Thus, the SCR 8 is triggered to conduct, and the charge of the charge / discharge capacitor 2 is discharged through the discharge circuit of the primary coil 5 of the ignition coil 4 and the discharge current flows through the primary coil 5 of the ignition coil 4. Therefore, a high voltage is induced in the secondary coil 6 of the ignition coil 4 and a predetermined spark is generated in the spark plug 7 to ignite.
[0020]
With this ignition operation, the ignition device shifts to a steady operation while performing an advance control of the ignition timing as the rotational speed increases from a low speed rotation to a predetermined rotation. Again during normal operation, the retard control capacitor 14 charging voltage and a reverse induced voltage B by the sum of the driving voltage applied to the driving terminal of SCR8 is more than predetermined, i.e., the Zener voltage V _Z or more Zener diode 16 Then, the Zener diode 16 becomes conductive.
[0021]
However, during normal operation, the Zener diode 16 is turned on at time T _{2 to} T ₃ and time T _{4 to} T ₅ shown in FIG. 2, and the time T _{5 to} T before and after the ignition timing control range including the ignition time T _{1. 2} , the Zener diode 16 becomes non-conductive, so that the level of the drive voltage changes according to the engine speed, and the SCR 8 is turned on and can be ignited at the optimum time at that speed.
[0022]
When the engine overspeed occurs, the reverse induced voltage B 1 becomes large. Therefore, as shown in FIG. 3, from the time T ₆ immediately after the retard control capacitor 14 starts discharging through the resistor 17, The sum of the drive voltage on the drive terminal side of the SCR ₈ and the charge voltage of the retard control capacitor 14 is equal to that of the Zener diode 16 until the time T ₈ immediately before the angle control capacitor 14 starts charging again with the main direction induced voltage A 1. It becomes Zener voltage _{V Z} above, the Zener diode 16 becomes conductive. That is, the Zener diode 16 in time before and after _T 6 through T ₈ of the ignition timing control range including the ignition timing _{T 7} becomes conductive.
[0023]
As a result, the level of the drive voltage applied to the drive terminal of the SCR 8 decreases, and it takes time for the drive voltage to rise to the trigger level of the SCR 8, and the SCR 8 becomes conductive at time T ₇ . Thus, by the action of the retarding circuit 13, delays the conduction timing SCR8 from time T ₁ of the 2 to time T ₇ of FIG. 3, since accordingly the ignition timing is delayed, it is possible to prevent overspeed of the engine.
[0024]
The charge of the retard control capacitor 14 is discharged through the discharge resistor 17 with a time constant determined by the discharge resistor 17 and the retard control capacitor 14 after being charged by the main direction induced voltage A 1. Accordingly, since the charging voltage of the retard control capacitor 14 when the reverse induced voltage B 1 is induced is changed by the resistance value of the discharge resistor 17, the engine speed at the start of the retard is determined by the resistance value of the discharge resistor 17. The retardation amount can be set easily and arbitrarily.
[0025]
In particular, since the main direction induced voltage A and the reverse direction induced voltage B of the generator coil 1 are compared to control the level of the driving voltage of the SCR 8, the circuit configuration of the entire apparatus having the ignition timing control function is simplified. There is an advantage that it can be manufactured easily and inexpensively as compared with the prior art, and the entire apparatus can be downsized. In addition, the simplification of the circuit can reduce variations in parts.
[0026]
As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to this embodiment. For example, a transistor other than the SCR 8 may be used as the switching element.
[0027]
The semiconductor element may be any element that conducts when the difference between the main direction induced voltage A and the reverse direction induced voltage B exceeds a predetermined value. A control element other than the Zener diode 16, such as a transistor, may be used. Also good.
[0028]
【The invention's effect】
In the present invention, the charging / discharging capacitor 2 is charged by the main direction induced voltage A of the power generation coil 1, and when the drive voltage by the reverse direction induced voltage B of the power generation coil 1 rises to a predetermined voltage, the switching element 8 is made conductive, In the capacitor charge / discharge type ignition device in which the charge of the charge / discharge capacitor 2 is discharged to the ignition coil 4, the drive circuit 9 of the switching element 8 is compared with the main-direction induced voltage A and the drive voltage of the switching element 8. Since the retard circuit 13 is provided to reduce the drive voltage of the switching element 8 and delay the ignition timing when the difference between the two is greater than a predetermined value, it can be easily and inexpensively manufactured with a simple circuit configuration, and the entire device Can be reduced in size, and problems due to variations in circuit elements are less likely to occur.
[0029]
Further, the retard control capacitor 14 charged by the main direction induced voltage A and the drive of the switching element 8 applied by the charge voltage of the retard control capacitor 14 and the reverse induced voltage B to the drive circuit 9 of the switching element 8 are driven. Since the semiconductor device 16 is provided which conducts when the difference from the voltage exceeds a predetermined value and reduces the drive voltage of the switching device 8, the circuit configuration can be further simplified.
[0030]
Further, a first charging circuit that charges the retard control capacitor 14 with the main direction induced voltage A 2 and a second charge circuit that charges the retard control capacitor 14 in the reverse direction with the reverse direction induced voltage B 2 when the semiconductor element 16 becomes conductive. Since the charging circuit is provided, the circuit configuration can be further simplified.
[0031]
In addition, since the discharge resistor 17 for discharging the charge of the retard control capacitor 14 is provided, the retard start and the retard width can be easily set.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an ignition device showing an embodiment of the present invention.
FIG. 2 is a waveform diagram showing an embodiment of the present invention.
FIG. 3 is a waveform diagram showing an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Generating coil 2 Charging / discharging capacitor | condenser 4 Ignition coil 8 SCR (switching element)
9 Drive circuit 13 Retardation circuit 14 Retardation control capacitor 16 Zener diode (semiconductor element)
17 Discharge resistance A Main direction induced voltage B Reverse direction induced voltage

Claims (4)

The charging / discharging capacitor (2) is charged by the main direction induced voltage (A) of the generator coil (1), and switching is performed when the drive voltage due to the reverse direction induced voltage (B) of the generator coil (1) rises to a predetermined voltage. In the capacitor charging / discharging ignition device in which the element (8) is conducted to discharge the charge of the charging / discharging capacitor (2) to the ignition coil (4), the drive circuit (9) of the switching element (8) In addition, the main direction induced voltage (A) and the driving voltage of the switching element (8) are compared, and when the difference between the two is greater than or equal to a predetermined value, the driving voltage of the switching element (8) is decreased and ignition is performed. A capacitor charge / discharge igniter comprising a retard circuit (13) for delaying the timing. In the drive circuit (9) of the switching element (8), the retard control capacitor (14) charged by the main direction induced voltage (A), the charge voltage of the retard control capacitor (14) and the reverse direction A semiconductor element (16) that conducts when the difference between the driving voltage of the switching element (8) applied by the induced voltage (B) exceeds a predetermined value and reduces the driving voltage of the switching element (8); The capacitor charging / discharging ignition device according to claim 1, further comprising: A first charging circuit that charges the retardation control capacitor (14) with the main direction induced voltage (A), and the retardation by the reverse direction induced voltage (B) when the semiconductor element (16) is conductive. The capacitor charging / discharging ignition device according to claim 2, further comprising a second charging circuit for charging the control capacitor (14) in the reverse direction. The capacitor charging / discharging ignition device according to claim 2 or 3, further comprising a discharge resistor (17) for discharging electric charge of the retardation control capacitor (14).

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