JPH051652A - Condenser charge and discharge type ignition device - Google Patents

Abstract

PURPOSE:To easily vary spark delay setting rotational speed without causing instability of rotational speed by gradually lowering a horse power according to rise of the rotational speed by way of delaying an ignition angle along with the rise of the rotational speed and by taking the state of opening of a throttle in an ignition device. CONSTITUTION:An ignition time control circuit to control a gate signal of an ignition circuit is provided, and this ignition time control circuit is provided with a condenser charge and discharge circuit 1 which is charged at the time when a negative timing pulse is delivered and discharged through a series circuit of resistance and resistance and transistors after it stops delivering the negative timing pulse, a circuit to deliver the gate signal to the base of the transistors Q1-Q4 and a level variable circuit to vary a standard level by a switch element to by-pass the gate signal and output of a throttle sensor S at the time when output of the condenser charge and discharge circuit 1 reaches the standard level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor charging / discharging type ignition device, and more particularly to improving a speed limiting feeling.

[0002]

2. Description of the Related Art As an engine ignition device,
The capacitor is charged by the output of the power generation coil rectified by the diode, and the ignition power source is applied to the discharging thyristor SCR by the transistor turned on by the positive timing pulse sent from the timing pulse generating coil. 2. Description of the Related Art Capacitor charging / discharging type ignition devices are widely used that ignite a plug by discharging an electric charge of a capacitor to an ignition coil. By the way, in this case, speed limitation may be required to prevent engine trouble due to overspeed. However, in the conventional one, when the capacitor charge / discharge ignition circuit is provided with an overspeed rotation speed setting circuit and the output from the timing pulse generating coil is used, it is detected that the rotation speed setting circuit has exceeded the predetermined speed. The output is sent out, thereby turning on the transistor and by-passing the ignition signal applied to the gate of the thyristor for discharging the transistor at the time of turning on, thereby preventing the discharge of the capacitor and suppressing the rotation speed. It is a limitation. Therefore, in the conventional method, it is easy to cause a rapid decrease in horsepower at the same time as a misfire and the rotational speed becomes unstable. Further, there is one that outputs the optimum ignition timing to the engine according to the throttle opening by arbitrarily changing the ignition timing according to the throttle opening. However, changing the ignition timing by the throttle has a method of calculating and outputting the ignition timing based on the data obtained by detecting the opening of the throttle in the CPU or the like, but this type of device is expensive. There is a drawback.

[0003]

OBJECT OF THE INVENTION The present invention has been made for the purpose of improving the above.

[0004]

According to the present invention, as shown in FIG. 1, the engine is operated at an appropriate constant ignition angle θ1 up to the upper limit rotation speed N1 in the normal operation rotation speed range, and the overrunning speed from N1 is exceeded. In order to detect the speed, in the rotational speed range up to the set rotational speed N2, that is, N1 to N2, the ignition angle is delayed in the rotational direction from θ1 to θ2 as the rotational speed increases, and the horsepower based on the increase in the rotational speed is gradually decreased. Let Further, by taking the state of the opening degree of the throttle into the ignition device, the ignition timing corresponding to the operating state of the engine is further output. Next, the present invention will be described in detail with reference to an embodiment circuit diagram.

[0005]

2 is a circuit diagram of an embodiment of the present invention, FIG.
FIG. 3 is a waveform diagram for explaining the operation. In FIG. 1, reference numeral 1 denotes a capacitor charge / discharge type ignition circuit main circuit, which is formed of the following parts. EXT indicates an alternating current generating coil, which is driven by the engine and outputs an alternating current output. D0 is a short-circuit diode element, which short-circuits the negative voltage of the magneto coil EXT. D2 is a rectifying diode, C1 is a charging / discharging capacitor, IGN is an ignition coil, PG is an ignition plug, and SCR is a discharging thyristor. Next, PC is a timing pulse generating coil, which is a reference positive timing pulse + P for each revolution of the engine as shown in FIG.
And a negative timing pulse -P whose time interval changes with the number of revolutions. Needless to say, reference numeral 2 is a control power supply circuit, and the operating power supply for each part of the main circuit of the present invention described below is configured by using a separate power supply and may be made from its own circuit.

Reference numeral 3 is a main circuit of the present invention, and Q1 and Q2 are transistors for waveform shaping of positive and negative timing pulses,
IC1 and IC2 are inverter circuits, D3 and D4 are rectifying diodes, C3 and C4 are charging capacitors, Q3 is a discharging transistor for the capacitor C3, R5 is a discharging resistor for the capacitor C4, and R6 and Q4 are capacitors. A resistor and a transistor for adjusting the discharge time constant of C4, G1 and G2 are level converters having a threshold level, S is a throttle sensor, and a throttle resistor (not shown) is interlocked with a variable resistor to open the throttle. By generating a potential according to the frequency and inputting it to one of the level converters G2, the threshold level of the level converter G2 is changed according to the input potential. Q5 is a gate signal side transistor, R7 and R8 are base resistors and R
9 and R10 are voltage dividing resistors.

In the basic operation of this essential circuit, first, the transistor Q1 is turned on by a positive timing pulse, and the capacitor C3 is charged through the inverter IC1 and the diode D3. Then, the transistor Q2 is turned on by the negative timing pulse, and the discharging transistor Q3 is turned on via the inverter IC2 to discharge the electric charge of the capacitor C3. FIG. 3B shows the waveform at the point b. On the other hand, when the transistor Q2 is on, the inverter IC2 and the rectifying diode D4
The capacitor C4 is charged via. Then, the capacitor C4 is discharged through the resistors R5 and R6 and the transistor Q4 as described later. FIG. 3 (c) shows a point waveform (c). The transistor Q4 is turned on when the output of the level converter G1 is high (H). At the same time, the thyristor SCR is also supplied with a gate signal and turned on. Further, the transistor Q5 is turned on when the output of the level converter G2 is high (H) and bypasses the gate signal of the thyristor SCR to turn it off. The ignition operation will be described below.

[0008]

[Operation when the number of revolutions is N1 or less] First, the operation will be described by ignoring the operation of the throttle sensor. Further, it is assumed that the time required to charge the capacitors C3 and C4 does not change due to the increase in the rotation speed. Further, it is assumed that the discharge time constant is set so that the charging voltage of the capacitor C4 becomes equal to or lower than the threshold level l1 (FIG. 3c) of the level converter G2 when the rotation speed is equal to or lower than N1. Further, when the capacitor C3 is charged, the gate signal is applied to the thyristor SCR through the level converter G1. In this state, the transistor Q5 is always off, and the thyristor SCR becomes conductive when the capacitor C3 is charged, that is, when the positive timing pulse + P is transmitted. That is, since the positive timing pulse generation position always has a constant relationship with the rotation of the engine, the ignition angle is constant (rotation speed N1) θ1 unless the discharge voltage level of the capacitor C4 exceeds the threshold voltage level of the level converter G2. The operation is maintained to obtain the characteristics shown in FIG.

[0009]

[Operation when the number of revolutions exceeds N1] The time required for one revolution of the engine is shortened as the number of revolutions increases, and the positive timing pulse + P and the next positive timing pulse +
The time interval t with P and the time interval T1 between the positive and negative timing pulses + P-P are also shortened. For this reason, the inclination of the capacitor C4 at the time of discharging does not change, but the charging / discharging cycle becomes gradually shorter as the rotation speed increases. Therefore, the discharge voltage level of the capacitor C4 rises as the rotation speed rises and reaches the threshold level of the level converter G2 as shown in FIG. 3 (c).
As shown in (b), when the speed becomes faster than point N1 in FIG. 1, the transistor Q5 is in the ON state at the arrival of the next positive timing pulse, and the gate signal by the positive timing pulse is bypassed by the transistor Q5. In addition, the ignition timing of the thyristor SCR is delayed from the timing of generation of the positive timing pulse, the discharge pressure level of the capacitor C4 becomes lower than the threshold level 11 of the converter G2, and the gate signal is turned off when the transistor Q5 is turned off. It will be given and ignited. Therefore, the ignition angle is retarded as θ1 → θ2. (FIG. 3d) The transistor Q4 is turned on when the output of the converter G1 is high, and a discharge circuit for the capacitor C4 is newly formed via the resistor R6. Therefore, the slope of the discharge of the capacitor C4 drops sharply in synchronization with the turning on of the transistor Q4.

[0010]

[Operation of Throttle Sensor] By varying the threshold level of the level converter G2, its output ignition characteristic changes as shown in FIGS. In this embodiment, by using a variable resistor and interlocking with the throttle lever,
It is possible to obtain the reference voltage according to the throttle opening. As an example, in the configuration example of R9, VR, and R10 in the figure, the output is given as the reference voltage of the level detector G2.
3 (e) shows an example of the throttle opening and the throttle output voltage. When this output voltage is changed like the threshold levels l1 to l2 in FIG. 3, the ignition timing output is N1 to
You can get a change like N2.

[0011]

As described above, according to the present invention, unlike the conventional case, the engine is not brought into the misfire state immediately as in the conventional case, but the retarding operation is performed, so that the change in the rotational speed becomes gentle, and the rapid decrease in the rotational speed is accompanied. It is possible to prevent a rapid decrease in horsepower and instability of the rotation speed. Further, there is an advantage that the retard angle set rotation speed can be easily changed by using the throttle sensor.

[Brief description of drawings]

FIG. 1 is a driving characteristic diagram of the present invention.

FIG. 2 is a circuit diagram of an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the present invention.

[Explanation of symbols]

 1 main circuit 2 control power supply circuit 3 main circuit EXT power generation coil C1 charge / discharge capacitor IGN ignition coil SCR thyristor PC timing pulse generation coil IC1, IC2 inverter circuit G1, G2 level converter Q1, Q2, Q3, Q4 transistor S Throttle sensor

Claims (1)

Claim: What is claimed is: 1. A capacitor charging / discharging type ignition device for igniting by discharging an electric charge of a capacitor charged by an output of a power generating coil to an ignition coil through a thyristor. The ignition timing control circuit includes an ignition circuit for transmitting a signal to the gate of the thyristor and an ignition timing control circuit for controlling the gate signal during the period from the transmission of the positive timing pulse to the suspension of the negative timing pulse. Is charged when the negative timing pulse is transmitted, and after the negative timing pulse transmission is stopped,
A capacitor charging / discharging circuit that is discharged through a resistor and a series circuit of a resistor and a transistor, and a base of the transistor.
When the output of the circuit for transmitting the gate signal to the gate and the output of the capacitor charging / discharging circuit reaches the reference level, the reference level can be varied by the switch element for bypassing the gate signal and the throttle sensor output. A capacitor charging / discharging ignition device, comprising: a level variable circuit.