JP2586145B2 - Ignition device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a current cutoff type ignition device for an internal combustion engine.

2. Description of the Related Art In general, a current cutoff type ignition device for an internal combustion engine includes an ignition power supply coil, and a main current control circuit that controls a current supplied to the ignition power supply coil to be interrupted at an ignition position of the engine.
A high voltage for ignition is obtained by further increasing the high voltage induced in the ignition power supply coil when the current flowing through the coil is cut off.

The present applicant has previously proposed an ignition device of this type shown in FIG. 6 (Japanese Patent Application No. 59-151371).

In the ignition device shown in FIG. 6, an ignition coil 1 is provided in a magnet generator driven by an engine, and a primary coil 1a of the ignition coil is used as an ignition power supply coil. The ignition plug 2 attached to the cylinder of the engine is connected to the secondary coil 1b of the ignition coil. Ignition power coil
The main current control circuit for controlling the conduction current of 1a includes a main current control transistor switch 3 including a transistor TR1 having a collector-emitter circuit connected in parallel to the ignition power supply coil 1a, and a switch for controlling the transistor switch. And a control circuit 4. The switch control circuit 4 includes resistors R1 and R2 for supplying a base current from the ignition power supply coil 1a to the transistor TR1,
A trigger circuit 402 'including transistors TR3 to TR5, resistors R3 to R5, and a peak detection capacitor C1, and a transistor TR6.
And a positive feedback circuit 403 including a resistor R6.

In the ignition device shown in FIG. 6, when the rotating shaft of the engine is rotated to induce a voltage Ve in the direction indicated by an arrow in the ignition power supply coil 1a, a base current Ib1 flows through the transistor switch 3 by the voltage Ve, and the transistor The switch 3 conducts. Therefore, a short-circuit current I1 flows from the ignition power supply coil 1a through the transistor switch 3. As the short-circuit current I1 increases with an increase in the voltage Ve, the voltage across the main current control transistor switch 3 increases. The capacitor C1 is charged by the voltage across the transistor switch 3, and a charging current Ic flows through the capacitor C1. This charging current causes the transistor TR4 to conduct. When the transistor TR4 is conducting, all the current flowing from the ignition power supply coil 1a through the resistor R5
PN junction between base and emitter, resistor R4 and transistor TR
4 through the collector-emitter of the transistor T
Transistor TR through PN junction between base collector of R5
The current is prevented from flowing through the base of 2.

When the current I1 reaches the peak value, the voltage between both ends of the main current control transistor switch 3 also reaches the peak value, and the capacitor
The charging current of C1 becomes zero. At this time, since the transistor TR4 is cut off, a base current is given to the transistor TR2 (cutoff control transistor) through the resistor R5 and the junction between the base and the collector of the transistor TR5.
TR2 conducts. As a result, the main current control transistor switch (transistor TR1) is turned off, and the current flowing through the ignition power supply coil 1a is cut off.

As a result, a high voltage is induced in the ignition power supply coil 1a in a direction in which the short-circuit current is to continue to flow, and the high voltage is further boosted by the ignition coil to induce a high voltage for ignition in the secondary coil 1b. Therefore, a spark is generated in the ignition plug 2 and the engine is ignited.

In this way, the ignition operation is performed at the peak position of the voltage between both ends of the main current control transistor switch 3 when the engine is running at a low speed.

At the time of high speed of the engine, the charging current of the capacitor C1 is flowing, and the voltage between the base of the transistor TR5 and the emitter of the transistor TR2 is the voltage between the base and the emitter of the transistor TR2 during the period when the current is flowing between the base and the emitter of the transistor TR5. When the transistor TR2
, A base current flows, and the transistor TR2 is turned on.
Therefore, at high engine speeds, the voltage between the base of transistor TR5 and the emitter of transistor TR2 becomes
The ignition operation is performed at a position where the voltage between the base and the emitter of R2 is reached, and the ignition position advances with an increase in the rotation speed of the engine. Thereby, at the time of high speed of the engine, the advance angle characteristic is obtained. The advance angle width in this case is determined by the waveform of the voltage between both ends (collector-emitter voltage) when the main current control transistor switch is turned on. As described above, when the advance characteristics are obtained using the waveform of the voltage between both ends of the main current control transistor switch, the advance angle width is limited to a value smaller than the angle width from the rising position to the peak position of the voltage. . In order to increase the advance angle width, it is necessary to design the generator so that the angle width from the rising position to the peak position of the positive voltage (voltage of the polarity used for the ignition operation) of the ignition power supply coil is as wide as possible. However, if the generator is designed to obtain a voltage having a simple sine waveform or a waveform similar to a sine wave, it is difficult to widen the angle width. Therefore, generally, as shown in FIG. 4 (A), the generator is designed so that a positive voltage E1 having a waveform in which two peaks P1 and P2 appear is obtained, and the peak is obtained from the rising position of the positive voltage. The angle width up to the position P2 is widened.

[Problem to be Solved by the Invention] In the above-mentioned ignition device, the advance angle characteristic is obtained by using the change in the waveform of the electric current at both ends of the main current control transistor switch.

That is, in order to increase the advance width, the waveform of the positive output voltage E1 of the ignition power supply coil is changed as shown in FIG.
It is necessary to widen the angular width from the rising position to the peak position. When a voltage having such a waveform is used, the waveform of the short-circuit current I1 flowing through the main current control transistor switch 3 is shown in FIG. becomes as shown by a broken line in a), the peak respectively at the position of the position and angle theta ₀ angle θ3 is waveform produced. Since the voltage waveform across the main current control transistor switch 3 to a waveform conforming to the waveform of the current I1, the step when such a voltage obtaining advance characteristics relying on the waveform, from the ignition position theta ₀ to θ3 Therefore, it is not possible to obtain a characteristic of linearly advancing linearly as the rotation speed increases.

In this case, in order to obtain a linear advance angle characteristic, the angle θ
It is necessary to lower the first peak generated in 3, but in such a case, the advance angle width cannot be widened.

When the advance characteristics are obtained by relying on the waveform of the voltage between both ends of the main current control transistor switch as described above, it is possible to easily adjust the inclination of the advance characteristics and the advance rotation speed. could not.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ignition device for an internal combustion engine in which a linear advance characteristic can be obtained by widening the advance angle width and the inclination of the advance characteristic can be freely adjusted. is there.

[Means for Solving the Problems] As shown in FIG. 1, the present invention relates to an ignition power supply coil 1a that successively outputs a negative voltage and a positive voltage in synchronization with the rotation of an internal combustion engine; A main current control transistor switch 3 which is connected in parallel to the power supply coil 1a and in which a base current flows by the positive output voltage of the ignition power supply coil to conduct, and a main current control transistor switch for ignition timing of the internal combustion engine; And a switch control circuit 4 for controlling to be in a cutoff state.

In the present invention, when the switch control circuit 4 is turned on, the first current control transistor switch 3 is connected to the main current control transistor switch 3 so that the transistor switch 3 is turned off.
And the second cutoff control transistor 401 is connected in parallel to the first cutoff control transistor, and the main current control transistor switch 3 is turned off when the transistor 401 is turned on.
And the peak position of the voltage between both ends when the main current control transistor switch 3 is turned on is detected, and the first shutdown control transistor 40 is detected at the peak position.
A peak trigger circuit 402 that gives a trigger signal to 1 to turn on the first shutoff control transistor, an advancing capacitor 405, and charges the advancing capacitor 405 with the negative output voltage of the ignition power supply coil 1a. A capacitor charging circuit for discharging the lead capacitor 405 through the trigger signal input terminal of the second shut-off control transistor 404 with a constant time constant, and the discharge current of the lead capacitor reaches a predetermined trigger level. And an advancing trigger circuit 406 for conducting the second shutoff control transistor 404, and a side for bypassing a part of the discharge current of the advancing capacitor through the diode and the base circuit of the first shutoff control transistor. A path circuit 407 is provided.

In the example shown in FIG. 1, a capacitor charging circuit is constituted by the diodes D3 and D4. R1 and R2 are resistors for applying a base current to the transistor switch 3.

[Operation] With the configuration described above, when the first cut-off control transistor is triggered at the peak position of the voltage between both ends when the main current control transistor switch is turned on, or when the discharge current of the advance capacitor 405 is reduced. When the predetermined trigger level is reached and the second shutoff control transistor is triggered, the main current control transistor switch is shut off and the ignition operation is performed.

Since the charging voltage of the advancing capacitor 405 is low when the engine is running at a low speed, the position where the discharge current of the capacitor reaches the trigger level is later than the peak position of the voltage across the main current control transistor switch 3. Therefore, when the engine speed is low, the peak trigger circuit 402 turns on the cutoff control transistor at the peak position (fixed position) of the voltage between both ends of the main current control transistor switch 3 to turn off the main current control transistor switch. To perform the ignition operation.

On the other hand, in the region at or above the advancing start rotation speed, the charging voltage of the advancing capacitor rises, and the advancing voltage is used at a position where the phase is advanced from the position where the voltage across the main current control transistor switch reaches a peak. The discharge current of the capacitor reaches the trigger level of the second shutoff control transistor. The position at which the discharge current of the advancing capacitor reaches the trigger level of the second cut-off control transistor advances as the charging voltage of the advancing capacitor increases with an increase in the rotational speed. It progresses with the rise.

The advance angle characteristic can be appropriately adjusted by adjusting the discharge characteristic of the advance capacitor.

Further, as described above, when a bypass circuit that bypasses a part of the discharge current of the advance capacitor through the diode and the base circuit of the first cutoff control transistor is provided, the base of the second cutoff control transistor is provided. Experiments have confirmed that the waveform of the applied signal can be made a linearly rising waveform as shown in FIG. 4 (D), so that the linearity of the advance angle characteristic can be improved.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows an embodiment of the present invention which embodies the configuration of FIG. 1. In FIG. 2, parts that are the same as the corresponding parts in FIG. 1 are given the same reference numerals. In this embodiment,
Although the main current control transistor switch 3 is composed of one NPN transistor TR1, the main current control transistor switch may be constituted by two Darlington-connected transistors. The collector and the emitter of the transistor TR1 are connected to one end (one end on the non-ground side in this example) and the other end of the primary coil 1a,
The base of TR1 is connected to one end of a primary coil 1a also serving as an ignition power supply coil via resistors R1 and R2. Therefore 1
When a voltage Ve in the direction indicated by an arrow is generated in the next coil 1a, a base current flows to the transistor TR1 through the resistors R2 and R1, and the transistor TR1 is turned on.

The cutoff control transistor 401 comprises an NPN transistor TR2, the collector of which is connected to one end of the primary coil 1a via a resistor R2, and the emitter of which is the primary coil TRa.
Each of them is connected to the other end of 1a.

In the peak trigger circuit 402, one end of the capacitor C1 is connected to one end of the primary coil 1a via a resistor R3,
The other end of the capacitor is connected to the base of a charging current detecting NPN transistor TR4 whose emitter is connected to the other end of the primary coil. The collector of the transistor TR4 is connected to the emitter of the NPN transistor TR5.
The collector of R5 is connected to the base of the transistor TR2 through a resistor R7, and the base of the transistor TR5 is connected to one end of the primary coil 1a through a resistor R5.
A diode D1 is connected between the base and the emitter of the transistor TR2.
However, a diode D2 is connected between the base and the emitter of the transistor TR4. Capacitor C1, transistors TR4, TR5, resistors R3, R5, R7 and diodes D1, D2
Constitute a peak trigger circuit 402.

Connect the transistor TR6 to the connection point between the capacitor C1 and the resistor R3.
And the collector of the transistor TR6 is connected to the base of the transistor TR2. The base of the transistor TR6 is connected to the transistor T through the resistor R6.
Connected to the collector of R2. A positive feedback circuit 403 is configured by the transistor TR6 and the resistor R6.

One end of the advancing capacitor 405 is connected to the cathode of the diode D3 whose anode is grounded, and the other end is connected to the anode of the diode D4 connected to one end of the ignition power supply coil 1a.

The second shut-off control transistor 404 comprises an NPN transistor TR7 whose emitter is grounded, and its collector is connected to the collector of the transistor TR2. A diode D6 having an anode facing the ground is connected between the base of the transistor TR7 and the ground.

The base of the transistor TR7 is connected to a connection point between the advance capacitor 405 and the diode D3 through the resistor R8. A resistor R9 is connected between the connection point between the advancing capacitor 405 and the diode D4 and the ground, and the advancing trigger circuit 406 is configured by the resistors R8 and R9.

The anode of the diode D5 is connected to the base of the transistor TR7, and the cathode of the diode D5 is connected to the base of the transistor TR2. The bypass circuit 407 is configured by the diode D5.

The ignition coil 1 is provided in a magnet generator as shown in FIG. This magnet generator has a flywheel 5 attached to the rotating shaft of the engine, a magnet 6 attached in a recess 5a provided on the outer periphery of the flywheel, and a predetermined gap on the outer periphery of the flywheel 5 via a predetermined gap. And a stator 7 arranged oppositely. The stator 7 includes a substantially C-shaped iron core 8, and the iron core 8 includes a primary coil 1a and a secondary coil 1b.
Is mounted.

In the ignition device for an internal combustion engine of the above embodiment, when the engine is rotated, a voltage E as shown in FIG. 4A is induced in the ignition power supply coil 1a. This voltage E is a negative voltage
It consists of En1, a positive direction voltage Ep, and a negative direction voltage En2.

When a positive voltage Ep is induced in the ignition power supply coil 1a, the resistance becomes
A base current flows through the transistor TR1 through R2 and R1, and the transistor TR1 becomes conductive. As a result, the short-circuit current I1 from the primary coil 1a through the transistor switch 3
(Indicated by a broken line in FIG. 4A). A voltage similar to the waveform of the current I1 is generated at both ends of the transistor switch 3. A current flows between the resistor R3, the capacitor C1, and the base and emitter of the transistor TR4 due to the voltage across the transistor switch 3, and the capacitor C1 is charged until the voltage across the transistor switch 3 reaches a peak value. At this time, current flows from one end of the primary coil 1a through the resistor R5, between the base and emitter of the transistor TR5, and between the collector and emitter of the transistor TR4, and no current flows through the base and collector of the transistor TR5. Therefore, at this time, no base current is supplied to the transistor TR2, and the transistor TR2 is kept in the cut-off state. When the voltage across the main current control transistor switch 3 reaches a peak, the charging current of the capacitor C1 becomes zero, and the transistor TR4 is turned off. At this time, current flows from the primary coil 1a through the resistor R5 and the base and collector of the transistor TR5, and the capacitor C1
Discharges between the resistor R3 and the emitter-collector of the transistor TR6 and between the resistor R7 and the base-emitter of the transistor TR2, so that a base current flows through the transistor TR2. Therefore, the transistor TR2 is turned on, and the main current control transistor switch 3 is turned off. Thereby, the primary coil 1a
High voltage is induced on the secondary coil
Since the ignition high voltage is output from 1b, the engine is ignited. Therefore, at a low speed of the engine, ignition is performed near a substantially constant position where the induced voltage of the primary coil (ignition power supply coil) reaches a peak.

On the other hand, the advance capacitor 405 is charged through the diodes D3 and D4 when the ignition power supply coil 1a outputs the negative voltage En1. This charging is performed with negative voltage En1
Until the peak is reached.

When the negative voltage En1 has passed its peak, the electrification of the capacitor 405 discharges through the resistor R8, between the base and the emitter of the transistor TR7, and through the resistor R9. When the discharge current of the capacitor 405 reaches a predetermined trigger level, the transistor TR7 is turned on, and the main current control transistor switch 3 is turned off to perform an ignition operation. Since the charging voltage of the capacitor 405 increases as the output voltage Vn1 of the ignition power supply coil increases as the rotation speed increases, the phase (ignition position) at which the discharge current of the capacitor 405 reaches the trigger level of the transistor TR7 is It progresses as the rotation speed increases.

FIG. 4B shows the waveform of the voltage Vb between the base of the transistor TR2 and the ground, and FIG. 4C shows the advance capacitor.
405 shows the waveform of the voltage Vc across the terminals 405. FIG. 4D shows a waveform of the voltage Vd between the base of the transistor TR7 and the ground. At a low speed of the engine, when the peak value of the voltage Vb reaches a predetermined trigger level Vt1 (for example, 0.3 V), the transistor TR2 is turned on to perform an ignition operation.

In the case where the trigger circuit 406 and the bypass circuit 407 by discharging the advance capacitor are not provided, the advance characteristic is obtained by using the waveform of the voltage Vb. Since the portion between the peak generated at the position of the angle θ and the peak generated at the position of the angle θ ₀ has a concave waveform, when the ignition position is advanced using this voltage Vb, a linear advance characteristic is obtained. Difficult to get.

On the other hand, a trigger circuit 406 based on the discharge current of the advancing capacitor 405 and a bypass circuit 407 that bypasses a part of the discharge current through the diode D5 and the base circuit of the transistor TR2 are provided. When the transistor switch 3 is cut off by conduction and the ignition operation is performed, the waveform of the voltage Vd generated between the base and the emitter of the transistor TR7 by the discharge current of the advancing capacitor is linear as shown in FIG. It has been clarified by an experiment that the magnitude of the voltage Vd increases as the rotational speed increases, as indicated by the broken line in the figure. In the ignition device of the present invention, since the ignition operation is performed when the voltage Vd having a waveform that rises linearly with the rotation of the engine reaches the predetermined trigger level Vt2, the ignition position is set at the rotation speed. As shown in FIG. 5, it is possible to obtain a characteristic in which the ignition position θi is linearly advanced above the advanced rotation speed Ns, as shown in FIG.

In the above embodiment, the advance start rotation speed and the inclination of the advance characteristic can be adjusted by appropriately setting the discharge time constant of the advance capacitor 405. Further, the advance angle characteristics are not affected by fluctuations in the air gap of the magnet generator provided with the ignition power supply coil, fluctuations in the amount of magnetization of the magnets, and the like.

In the above embodiment, after a spark is generated in the spark plug,
According to the combustion state of the internal combustion engine, the spark is once stopped, and when the voltage applied between the collector and the emitter of the transistor switch 3 becomes zero or negative, the circuit operation returns to the initial state. Thereafter, the transistor switch 3 conducts again by the energy remaining in the magnet generator, and then performs a shutoff operation. When such a state occurs, a part of the ignition energy is consumed in the ignition circuit, and the spark energy decreases.

In order to prevent such a situation from occurring, in the above-described embodiment, the positive feedback circuit 403 is provided so that even when the collector-emitter voltage of the transistor switch 3 becomes zero or negative, the main current control control transistor switch is provided. 3 can be maintained in a cut-off state.

In the above embodiment, instead of providing the diodes D1 and D2, a transistor TR3 is provided in the same manner as the conventional circuit shown in FIG. 6, and a PN junction between the base emitter and the base collector of the transistor is used as a diode. You can also.

Further, in the above embodiment, the PN junction between the base and the emitter and between the base and collector of the transistor TR5 is used instead of the diode, but these PN junctions can be replaced with individual diodes. In addition, the ignition power supply coil is connected to the anode of one diode through resistor R5.
1a, and the cathode of the diode may be commonly connected to the resistor R4 and the base of the transistor TR2.

In the above embodiment, the primary coil of the ignition coil also serves as the ignition power supply coil. However, the ignition coil is provided outside the magnet generator, and the power generation coil provided in the magnet generator is used as the ignition power supply coil. The present invention is also applicable to a current cutoff type ignition device in which an ignition power supply coil is connected in parallel to the main current control transistor switch 3 and the primary coil of the ignition coil.

[Effects of the Invention] As described above, according to the present invention, the first power supply control transistor and the second power supply control transistor are provided to cut off the main current control transistor switch, and the ignition power supply coil is provided. An advancing capacitor charged by the negative direction voltage, an advancing trigger circuit for applying a base current to a second cutoff control transistor by a discharging current of the advancing control capacitor, and a part of the discharging current. By providing a bypass circuit that bypasses through a diode and a base circuit of a first shutoff control transistor, an ignition device capable of obtaining a sufficiently wide advance angle and linearly obtaining an advance characteristic. Was realized.

Further, by adjusting the discharge time constant of the advancing capacitor, the advancing start rotation speed and the inclination of the advancing characteristics can be appropriately adjusted, so that the degree of freedom in designing the ignition device can be increased. Furthermore, since the advance angle characteristic is obtained without depending on the output voltage waveform of the ignition power supply coil, there is an advantage that the constant advance angle characteristic can always be obtained without being affected by the characteristics of the generator.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG.
FIG. 3 is a circuit diagram showing an embodiment of each part of the drawing, FIG. 3 is a front view of a main part showing a configuration of a generator used in the embodiment of the present invention, and FIG. 4 is a signal waveform of each part in FIG. FIG. 5 is a diagram showing an example of the advance angle characteristic obtained by the present invention, and FIG. 6 is a circuit diagram showing a conventional ignition device. DESCRIPTION OF SYMBOLS 1 ... Ignition coil, 1a ... Ignition power supply coil (primary coil), 2 ... Ignition plug, 3 ... Main current control transistor switch, 401 ... First cutoff control transistor, 402 ... Peak trigger Circuit, 404... Second cutoff control transistor, 405... Lead angle capacitor, 405... Lead angle trigger circuit, 407.

Claims (1)

(57) [Claims] 1. An ignition power supply coil for successively outputting a negative voltage and a positive voltage in synchronization with rotation of an internal combustion engine, and an ignition power supply coil connected in parallel to the ignition power supply coil and having a positive direction. A main current control transistor switch that conducts when a base current flows by an output voltage; and a switch control circuit that controls the main current control transistor switch to be in a cutoff state at an ignition timing of the internal combustion engine. An ignition device for an internal combustion engine which obtains a high voltage for ignition by boosting a voltage induced in the ignition power supply coil by shutting off a control transistor switch, wherein the switch control circuit comprises: Between a first shut-off control transistor connected to the transistor switch so that A second cut-off control transistor that connects the main current control transistor switch to a cut-off state when a path is connected in parallel to a collector-emitter circuit of the first cut-off control transistor and conducts; A peak trigger circuit for applying a trigger signal to the first cut-off control transistor at a peak position of a voltage between both ends when the current control transistor switch is turned on to make the first cut-off control transistor conductive; A capacitor; a capacitor charging circuit for charging the advance capacitor with a negative output voltage of the ignition power supply coil; and discharging the advance capacitor with a constant time constant through a base circuit of the second cutoff control transistor. When the discharge current of the advance capacitor reaches a predetermined trigger level, the second shut-off control transformer is turned off. An advancing trigger circuit for conducting a star, and a bypass circuit for bypassing a part of the discharge current of the advancing capacitor through a diode and a base circuit of the first cutoff control transistor. Ignition device for an internal combustion engine.