JPH0663499B2 - Capacitor charge / discharge ignition device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a capacitor charge / discharge type ignition device, and more particularly to improvement of a speed limiting feeling.

(Prior Art and its Problems) As an engine ignition device, as shown in FIG.
_The negative voltage is short-circuited by _{0, the} capacitor C ₁ is charged by the output of the power generation coil EXT rectified by the diode D _1, and the transistor Q is turned on by the positive timing pulse sent from the timing pulse generating coil PC. By supplying an ignition power supply from the control circuit power supply C ₂ to the discharging thyristor SCR by ₂ and Q ₁ , the electric charge of the capacitor C ₁ is discharged to the ignition coil IGN and the plug PG is ignited. The device is widely used.

By the way, in this case, speed limitation is often required in order to prevent engine trouble due to overspeed. However, the conventional one has a capacitor charging / discharging type ignition circuit (a) and an overspeed rotation speed setting circuit (b) as shown in the circuit diagram of FIG.
And a misfire control circuit (c) are provided so that the output from the timing pulse generation coil PC is used to output the output when it is detected that the rotation speed setting circuit (b) is overspeeding above a predetermined rotation speed. As a result, the transistor Q of the misfire control circuit (c) is turned on to bypass the ignition signal applied to the gates of the on-time discharge thyristors SCR of the transistors Q ₂ and Q ₁ , thereby bypassing the capacitor C ₁ . The discharge is blocked to limit the rotation speed. Therefore, in the conventional method, there is a drawback that the so-called speed limiting feeling is bad because a situation in which the rotational speed becomes unstable is likely to occur due to a sudden decrease in horsepower upon misfire.

(Object of the Invention) The present invention has been made for the purpose of improving the feeling of speed limitation.

(Means of the Present Invention for Solving Problems) In the present invention, as shown in FIG. 2, the engine is operated at an appropriate constant ignition angle θ ₁ up to the upper limit engine speed N ₁ in the normal operating speed range, in the rotational speed range i.e. N ₁ to N ₂ from N ₁ to reach the set rotation speed N ₂ for overspeed detection, allowed to send the ignition angle with increasing rotation speed in the rotation direction from theta ₁ to theta ₂ rotation The horsepower due to the increase in the number is gradually reduced.
When the rotation speed exceeds the set overspeed rotation speed N ₂ ,
The thinning ignition is performed to limit the increase of the rotation speed, and finally the misfire is started when the rotation speed exceeds the set upper limit rotation speed N ₃ , so that the rotation due to the sudden decrease of the horsepower as in the conventional device is performed. This is to prevent instability of numbers.

Next, the present invention will be described in detail with reference to an embodiment circuit diagram.

(Structure of Embodiment) FIG. 3 is a circuit diagram of an embodiment of the present invention, and FIGS. 4 to 7 are waveform diagrams for explaining the operation thereof. The same reference numerals as those in FIG. 1 show the same portions. .

In FIG. 3, I is a capacitor charging / discharging type ignition circuit, which is formed of the following parts. EXT indicates an AC generator coil, which is driven by the engine and sends out an AC output.
D ₀ is a diode element for short circuit,
Short the negative voltage of. D ₂ is a rectifying diode, C
₁ is a charging / discharging capacitor, IGN is an ignition coil, P
G is a spark plug, SCR is a discharge thyristor, and PC is a timing pulse generating coil. This is a reference positive timing pulse P for each engine revolution as shown in FIG. 4 (a).
And a negative timing pulse P whose time interval changes according to the number of revolutions. R ₂ and R ₃ are resistors and D
Reference numeral ₄ is a diode for selecting a positive timing pulse, Q ₁ and Q ₂ are transistors, and R ₄ is a resistor.

II is a control power supply circuit, which is formed of the following parts. D ₁ is a rectifying diode, R ₁ is a resistor, C ₂ is a capacitor, DZ ₂ is a constant voltage element, and the capacitor C ₂ is charged by the voltage obtained by stabilizing the rectified output of the generator coil EXT with the constant voltage element DZ _2. However, it is needless to say that various operating power supplies for the main circuit of the present invention described below are produced from their own circuits, and different power supplies may be used.

Reference numeral III is a main circuit of the present invention, which comprises a timing circuit A, a retarding circuit B, a thinning ignition circuit C, a misfire circuit D, and a drive circuit E, each of which is formed of the following respective parts.

In the timing circuit A, D ₅ is a negative timing pulse selection diode, R ₅ is a resistor, and Q ₃ is a transistor. In the retarding circuit B, R ₆ is a resistor, Q ₄ is a transistor, C ₄ is a charging / discharging capacitor, R ₉ is its discharging resistor, IC ₁ is an inverter circuit, and this IC ₁ is FIG. 4 (c). 1 / of the charging voltage level of the capacitor C ₄
It has a threshold ₁ of 2. Then, the capacitor C ₄ is charged to the output voltage of the control power supply circuit II through the transistor Q ₄ which is turned on only during the sending period of the negative timing pulse P as shown in FIG. 4C, and the sending of the negative timing pulse is stopped. Then, it is discharged through the discharging resistor R ₉ . Further, the inverter circuit IC ₁ sends out an "H" level output when the discharge voltage level of the capacitor C ₄ is below the threshold level l ₁ and sends out an "L" level output above.

In the thinning ignition circuit C, IC ₅ is an inverter circuit, IC ₃
Is a decimal counter, IC ₄ is an OR circuit, IC ₆ is an AND circuit,
A R _{1 2} are resistors, decimal counter IC ₃ is the timing set for each negative timing pulse P is turned on, for example, the output terminals O 1 / 2,1 / 3 ... periods, such as the negative timing pulse period Outputs are sequentially sent from ₁ , O ₂ , O _3, ... O _9, and the output of the OR circuit IC ₄ is applied to the other terminal of the AND circuit IC ₆ to which the negative timing pulse P is applied to one terminal. Then, the IC ₆ sends out a pulse signal at every other negative timing pulse, for example, as shown in FIG. 5 (e).

In the misfire circuit D, R ₇ is a resistor, Q ₅ is a transistor,
C ₅ is a charging / discharging capacitor, R ₈ is its discharging resistance, and the output voltage of the control power supply circuit II causes the output voltage of the control power supply circuit II to pass through the transistor Q ₅ which is turned on when the negative timing pulse P is transmitted. As described above, the capacitor C _{4 of the} retard circuit B
Is charged to the same voltage as. When the transmission of the negative timing pulse P is stopped and Q ₅ is turned off, the resistance R ₈
Through the capacitor C _{4 in} a shorter time than the discharge time of the capacitor C ₄ . IC ₂ is a buffer circuit, and as shown in FIG. 4 (d), 1 / of the charging voltage level of the capacitor C ₅
It has a threshold level l ₂ of ₂ and compares it with the discharge voltage level of the capacitor C ₅ with this as a reference level. When the discharge voltage level of C ₅ is below the reference level, it is “L” level, and above it is “ Sends H "level output. In the ignition drive circuit E, D ₃ is a reverse current blocking diode, C ₃ is a capacitor, and it is turned on when the positive timing pulse P is sent through the transistor Q ₁ of the ignition circuit A as shown in FIG. 4 (a). Control power supply circuit II
It is charged as shown in FIG. 4 (b) by the output voltage of and the ignition power source of the discharging thyristor SCR is produced. Q ₆ is firing control transistor of the discharge thyristor SCR, a Q ₇ is retarded ignition transistor, the on-off by the output of the inverter circuit IC ₁ of the retard circuit B is controlled. Q
Reference numeral ₈ denotes a misfire control transistor, which is the misfire circuit D
ON / OFF of the buffer circuit IC ₂ is controlled by the output of the buffer circuit IC _{2 and} the base control input applied from the inverter IC ₁ to the transistor Q ₇ and the AND circuit IC of the thinning ignition circuit C.
Bypassing the base control input of transistor Q ₇ from ₆ prevents Q ₇ from turning on.

In addition, R _{1 0} , R _{1 1} , R _{1 2} , R _{1 3} and R _{1 4} are resistors.
Next, the operation of the circuit of the present invention will be described step by step with reference to the waveform diagrams shown in the circuit diagrams of FIGS. 4 to 7 in FIG.

(Operation when the rotation speed is N ₁ or less) It is assumed that the time required for charging and discharging the capacitors C ₄ and C ₅ does not change due to the increase in the rotation speed (strictly, the width of the negative timing pie is changed by the change in the rotation speed. As it becomes smaller, the charging / discharging time will be somewhat shorter).

The discharge voltage levels of the capacitors C ₄ and C ₅ at the time of sending the positive timing pulse P are both the threshold level l _{1 of the} inverter circuit IC ₁ and the buffer circuit IC ₂ as shown in FIGS. , l ₂ or less, this state is IC ₁
And the intersection of the discharge voltage level of the shredding Hold Level and the capacitor C ₄ of continues for a period T ₁ of the to a point where charging of the new capacitor C ₄ by sending a negative timing pulse P is started. Therefore, during this period T _1, the output level of IC ₁ continues to be “H” and the output level of IC ₂ continues to be “L”, and accordingly, the transistors Q ₇ and Q ₆ are on for the period of T ₁ ,
Q ₈ is turned off. Therefore, the discharging thyristor SCR is fired at every rising of the positive timing pulse P as shown in FIG. 4 (a) to discharge the capacitor C ₁ and ignite as shown in FIG. 4 (f). At this time, the output of the AND circuit IC ₆ of the thinning ignition circuit C is sent when the negative timing pulse P is sent as in the case of the fourth (e), that is, after discharging the capacitor C ₁ by sending the positive timing pulse. Therefore, even if the transistor Q ₇ is turned on, it is not reignited.

That because the positive timing pulse generation position is always constant relationship with the rotation of the engine, the ignition angle as long as the discharge voltage level of the capacitor C ₄ does not exceed the shredding hold level of the inverter circuit IC ₁ (rotational speed N ₁₎ θ ₁ The operation of maintaining the constant ignition angle of is performed, and the characteristics of FIG. 2 are obtained.

(Operation until the number of revolutions exceeds N ₁ to reach N ₂ ) As the number of revolutions increases, the time required for one revolution of the engine becomes shorter. As a result, as shown in FIG. , The time interval t between the positive timing pulse P and the time interval T between the positive and negative timing pulses PP.
_{1 is} also shortened. Therefore, the slopes of the capacitors C ₄ and C ₅ during discharging are not changed, but the charging / discharging cycle is gradually shortened as shown in FIGS. 5, 6, and 7 as the rotation speed increases. Therefore, the capacitors C ₄ , C ₅ due to the negative timing pulse P
The charging start position, that is, the intersection of the threshold level l _{1 of the} IC ₁ and the discharge voltage level of the capacitor C ₄ gradually increases to the position where the positive timing pulse P, which always stays at a constant position with respect to the engine, is generated as the rotation speed increases. The rising position of the approaching positive timing pulse P is N _{1 in} FIG. 5 (c).
Cross the point. And at this time, the inverter IC _{1 of the} delay circuit B
The output level from the "H" changes to "L", the output level of the buffer circuit IC ₂ misfire circuit D is still maintained at "L" level.

Therefore, ignition is not performed at the rising point of the positive timing pulse P, and the transistors Q ₇ and Q ₆ are turned on at the point where the output level of the inverter circuit IC ₁ switches from "H" to "L", and the positive timing pulse P The discharge thyristor SCR is ignited by the charge of the capacitor C ₃ charged at the time of delivery, and the ignition is performed at an angle of θ _{2 in} FIG. 5 (f).

The ignition angle further shortens the time interval T ₁ between the positive timing pulse P and the negative timing pulse P due to the increase in the rotational speed, and the charging start position of the capacitors C ₄ and C ₅ approaches the positive timing pulse generation position. Accordingly, the ignition position deviates in the rotational direction of the engine to increase the retard angle, and the discharge voltage level of the capacitor C _{4 at} the positive timing pulse generation position is always higher than the threshold level l ₁ of the inverter circuit IC _1. When it becomes N ₂ , ignition by the output of the inverter IC ₁ of the retarding circuit B is not performed.

That is, in the range of N ₁ to N ₂ , as the rotation speed increases, the operation is performed such that the retard angle is increased and the horsepower is gradually decreased as shown in FIG.

(Operation until the rotation speed exceeds N ₂ and becomes N ₃ ) The rotation speed further increases and the discharge voltage level of the capacitor C ₄ becomes the threshold of the inverter circuit IC ₁ as shown in FIGS. 6 (c) and 6 (d). When the output level of IC ₁ is always "L" and the discharge voltage level of the capacitor C ₅ is less than or equal to the threshold level of the buffer circuit IC ₂ and the output level of IC ₂ is "L" beyond the level l _1. In the range, the transistors Q ₇ and Q ₆ are not turned on by these outputs. However, instead of this, the AND circuit of the thinning ignition circuit C
Since the output from the IC ₆ is added to the transistor Q ₇ every time the negative timing pulse P is sent out as shown in FIG. 6 (e), the discharge thyristor SCR is ignited by the charge of the capacitor C ₃ each time. Thus, thinning-out ignition is performed as shown in FIG. 6 (f). And this thinning-out ignition is the capacitor C
_4, C ₅ of the discharge voltage level, as in the FIG. 7 (c) (d), together Uwamawa' the shredding and hold l ₂ of the inverter circuit IC ₁ and the buffer circuit IC _2, an output level IC ₁ 'is The rotation is continued until the rotation speed N ₃ becomes “L” and the output level of the IC ₂ becomes “H”.

(Operation when the number of revolutions exceeds N ₃ ) The number of revolutions further increases and exceeds the number of revolutions N _3, and FIG.
As shown in (d), the discharge voltage levels of the capacitors C ₄ and C ₅ both exceed the threshold levels l ₁ and l ₂ of the inverter circuit IC ₁ and the buffer circuit IC ₂ , and the output level of the IC ₁ becomes “L”. ", the output level of the IC ₂ is" H ", the transistor Q ₈ by the output of the IC ₂ is turned on. Therefore IC
_The transistor Q ₇ is not turned on by the output of ₁ and the output pulse of the AND circuit IC ₆ of the thinning ignition circuit C is bypassed by Q ₈ at this time, so that the output of IC ₆ turns on the transistor Q ₇ . Will not be done. Therefore, as shown in FIG. 7 (f), ignition is not performed and the rotation speed N is changed as shown in FIG.
_{At 3} or more, a misfire occurs and the rotation speed is reduced.

Therefore, if the charging / discharging cycle of the capacitors C ₄ and C ₅ is selected so as to obtain the predetermined set rotational speeds N ₁ , N ₂ and N ₃ , the speed control feeling is improved as compared with the case of only misfire control. it can.

(Effects of the Invention) As described above, in the present invention, when the engine is overspeeding, the misfire state is not immediately brought to the conventional state, but thinning ignition is performed to suppress the increase in the rotation speed, and then the misfire state is established. Becomes loose. It is possible to prevent the instability of the rotation speed due to a sudden decrease in horsepower due to the rapid decrease in the rotation speed. Therefore, according to the present invention, the speed limiting feeling can be improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a conventional circuit diagram, FIG. 2 is an operation characteristic diagram of the present invention, FIG. 3 is an embodiment circuit diagram of the present invention, and FIGS.
The figure is a waveform diagram for explaining the operation.

Claims (1)

[Claims] 1. A capacitor charging device for igniting by turning on a discharging switching element at the time of sending out a positive timing pulse from a timing pulse generating coil and discharging the electric charge of a capacitor charged by an output of a power generation coil through an ignition coil. In the discharge type ignition circuit, a delay circuit having a capacitor charging / discharging circuit that is charged when the negative timing pulse is sent from the timing pulse generating coil and discharged after the negative timing pulse sending is stopped and a negative timing pulse that is charged when the negative timing pulse is sent. A misfire circuit having a capacitor charging / discharging circuit that is discharged after the timing pulse transmission is stopped, a thinning ignition circuit that transmits a pulse output of a number smaller than the negative timing pulse in synchronization with the transmission of the negative timing pulse, and the delay circuit. Compare the output with the misfire circuit to the reference level respectively. When the output level of the retarding circuit is "H", the switching element for ignition control is turned on, ignition is performed by a positive timing pulse, and the rotation speed increases and the output of the retarding circuit is "H", the discharge thyristor point When the switching element for arc control is turned on, ignition is performed only by the power source for ignition, and when the number of revolutions further increases and the output of the retarding circuit becomes "L", the output of the thinning ignition circuit is switched for ignition control. In addition to the element, this is turned on to ignite with a negative timing pulse, and when the rotational speed further increases and both the retard circuit output and the misfire circuit output become "L", the ignition control switching element is turned off. At the same time, an ignition drive circuit that short-circuits the output of the thinning ignition circuit is provided, and a capacitor charging / discharging ignition device.