JPH0378568A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To obtain the advance timing characteristic linearly settable by constituting a switch control circuit, which controls a main current controlling switch so as to be placed in a cut off condition in the predetermined ignition timing, of the first and second cut off controlling transistors and an advance timing trigger circuit or the like. CONSTITUTION:In the case of a switch control circuit 4 for controlling a main current controlling transistor switch 3 so as to be placed in a cut off condition in the predetermined ignition timing, the first cut off controlling transistor Tr401 for placing the switch 3 in the cut off condition at the time of conducting this circuit 4 is provided, and the second cut off controlling transistor Tr404 for placing the switch 3 in the cut off condition at the time of conduction is provided in parallel to this transistor Tr401. While a peak trigger circuit 402, which gives a trigger signal to the transistor Tr401 in a peak position of both end voltages at the time of conducting the switch 3, and a charging circuit for charging an advance timing capacitor 405 are provided. The capacitor 405 is discharged in a predetermined time constant by an advance timing trigger circuit 406 so as to conduct the transistor Tr404 by a discharge current value of predetermined level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a current interrupt type ignition device for an internal combustion engine.

[Prior Art] In general, a current interrupt type ignition device for an internal combustion engine includes an ignition power supply coil and a main current control circuit that controls the energizing current of the ignition power supply coil to be interrupted at the ignition position of the engine. A high voltage for ignition is obtained by further boosting the high voltage induced in the coil when the current flowing through the power supply coil is cut off.

The present applicant previously proposed an ignition device of this type as shown in FIG. 6 (Japanese Patent Application No. 151371/1982).

In the ignition system 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. A spark plug 2 attached to a cylinder of the engine is connected to a secondary coil 1b of the ignition coil. The main current control circuit that controls the current flowing through the ignition power supply coil 1a includes a main current control transistor switch 3 consisting of a transistor TRI whose collector-emitter circuit is connected in parallel to the ignition power supply coil 1a, and this transistor switch. It is constituted by a switch control circuit 4 for controlling. The switch control circuit 4 includes resistors R1 and R2 that supply base current from the ignition power supply coil 1a to the transistor TRI;
Cutoff control transistor 4 consisting of transistor TR2
01゛, transistors TR3 to TR5 and resistor R3
Trigger circuit 402' consisting of R5 and peak detection capacitor C1, transistor TR6 and resistor R6
It consists of a positive feedback circuit 403 consisting of.

In the ignition system shown in FIG. 6, when the rotation shaft of the engine is rotated, a voltage Ve in the direction of the arrow shown in the ignition power supply coil 1a is applied to the ignition power supply coil 1a.
When induced, base current Ibl flows through the transistor switch 3 due to the voltage Ve, and the transistor switch 3 becomes conductive. Therefore, a short circuit current 11 flows from the ignition power supply coil 1a through the transistor switch 3. Voltage V
As the short-circuit current 11 increases as e increases, the voltage across the main current control transistor switch 3 increases. A capacitor CI 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 TR
4 is conductive. When the transistor TR4 is conductive, all the current flowing from the ignition power supply coil 1a side through the resistor R5 flows through the PN junction between the base emitter of the transistor TR5 and between the resistor R4 and the collector-emitter of the transistor TR4, and the current flows from the base-collector of the transistor TR5. Current is prevented from flowing to the base of transistor TR2 through the PN junction between them.

When the current (1) reaches its peak value, the voltage across the main current control transistor switch 3 also reaches its peak value, and the charging current of the capacitor C1 becomes zero. At this time, transistor TR
4 is cut off, a base current is applied to the transistor TR2 (cutoff control transistor) through the resistor R5 and the base-collector junction of the transistor TR5, making the transistor TR2 conductive. As a result, the main current control transistor switch (transistor TRI') enters a cutoff state, cutting off the current flowing through the ignition power supply coil 1a.

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

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

When the engine is running at high speed, a charging current is flowing through the capacitor C1, and during the period when the current is flowing between the pace emitters of the transistor TR5, the voltage between the base of the transistor TR5 and the emitter of the transistor TR2 becomes the pace emitter voltage of the transistor TR2. When the base current reaches transistor TR2, the base current flows through transistor TR2.
2 is conductive. Therefore, when the engine is running at high speed, the transistor T
Ignition occurs at a position where the voltage between the base of R5 and the emitter of transistor TR2 reaches the pace-emitter voltage of transistor TR2, and this ignition position progresses as the rotational speed of the engine increases. This provides advanced angle characteristics when the engine is at high speed. In this case, the advance angle width is the voltage across the main current control transistor switch when it is conductive (
It is determined by the waveform of the collector-emitter voltage. In this way, when obtaining advance angle characteristics using the waveform of the voltage across the main current control transistor switch, the advance angle width is limited to a value smaller than the angular 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 angular width from the rising position of the ignition power supply coil's positive direction voltage (voltage of polarity used for ignition operation) to the peak position is as wide as possible. However, if the generator is designed to obtain a voltage with a simple sine waveform or a waveform similar to a sine wave, it is difficult to widen this angular width. Therefore, in general, a generator is designed to obtain a positive voltage E1 with a waveform in which two peaks Pi and P2 appear, as shown in FIG. The angular width up to position P2 is made wide.

[Problems to be Solved by the Invention] In the above-mentioned ignition device, the advance angle characteristic was obtained by utilizing a change in the waveform of the voltage across the main current control transistor switch, and therefore there were the following problems.

That is, in order to widen the advance angle width, the waveform of the positive direction output voltage E1 of the ignition power supply coil is changed as shown in FIG. 4(A),
It is necessary to widen the angular width from the rising position to the peak position, but when using a voltage with such a waveform, the waveform of the short-circuit current ■1 flowing through the main current control transistor switch 3 is as shown in Figure 4. The waveform becomes as shown by the broken line in (A), with peaks occurring at the position of angle θ3 and the position of angle θO, respectively. The voltage waveform across the main current control transistor switch 3 follows the waveform of this current 11, so if we rely on such a voltage waveform to obtain the advance angle characteristic, the ignition position will be stepped from θO to θ3. Therefore, it is not possible to obtain the characteristic of linearly advancing the angle as the rotational speed increases.

In this case, in order to obtain linear advance angle characteristics, the angle θ3
It is necessary to lower the first peak that occurs at , but in that case it is not possible to widen the advance angle width.

In addition, when the lead angle characteristic is obtained by relying on the waveform of the voltage across the main current control transistor switch as described above, it is easy to adjust the slope of the lead angle characteristic and the advance start rotation speed. could not.

An object of the present invention is to provide an ignition device for an internal combustion engine that can obtain a linear advance characteristic by widening the advance angle width, and also allows the slope of the advance angle characteristic to be freely adjusted. be.

[Means for Solving the Problem] As shown in FIG. 1, the present invention provides an ignition power supply coil 1a that successively outputs a negative direction voltage and a positive direction voltage in synchronization with the rotation of an internal combustion engine, and an ignition A main current control transistor switch 3 is connected in parallel to the power supply coil 1a and conducts when a base current flows due to the positive output voltage of the ignition power supply coil, and a main current control transistor switch 3 is connected at the ignition timing of the internal combustion engine. It is constituted by a switch control circuit 4 that controls the switch to be in a cut-off state.

In the present invention, a first cutoff control transistor 401 connected to the main current control transistor switch 3 so as to put the main current control transistor switch 3 into a cutoff state when the switch control circuit 4 becomes conductive; A second transistor that is connected in parallel to the control transistor and turns off the main current control transistor switch 3 when it becomes conductive.
The peak position of the voltage across both the cutoff control transistor 404 and the main current control transistor switch 3 when they are conductive is detected, and a trigger signal is given to the first cutoff control transistor 401 at the peak position. A peak trigger circuit 402 that turns on the cutoff control transistor, an advance angle capacitor 405, a capacitor charging circuit that charges the advance angle capacitor 405 with the negative output voltage of the ignition power supply coil 1a, and an advance angle capacitor 405. is discharged at a constant time constant through the trigger signal input terminal of the second cutoff control transistor 404, and when the discharge current of the advance angle capacitor reaches a predetermined trigger level, the second cutoff control transistor 404 is activated. An advance angle trigger circuit 406 that conducts conduction, and a bypass circuit 407 that bypasses a part of the discharge current of the advance angle capacitor through a diode and the base circuit of the first cutoff control transistor are provided.

In the example shown in FIG. 1, a capacitor charging circuit is constituted by diodes D3 and D4.

Further, R1 and R2 are resistors that supply base current to the transistor switch 3.

[Function] With the above configuration, when the first cutoff control transistor is triggered at the peak position of the voltage across the main current control transistor switch when it is conductive, or when the discharge current of the advance angle capacitor 405 is When a predetermined trigger level is reached and the second cutoff control transistor is triggered, the main current control transistor switch is cut off and an ignition operation is performed.

When the engine is at low speed, the charging voltage of the advance angle capacitor 405 is low, so that the position at which the discharge current of the capacitor reaches the trigger level is delayed from the peak position of the voltage across the main current control transistor switch 3. Therefore, when the engine is running at low speed, the peak trigger circuit 402 conducts the cutoff control transistor at the peak position (regular position) of the voltage across the main current control transistor switch 3 to turn the main current control transistor switch into the cutoff state. to perform the ignition operation.

On the other hand, in the region above the advance angle starting rotation speed, due to the increase in the charging voltage of the advance angle capacitor, the advance angle is started at a position where the phase is more advanced than the position where the voltage across the main current control transistor switch reaches its peak. The discharge current of the capacitor reaches the trigger level of the second cutoff control transistor. The position where the discharge current of the advance angle capacitor reaches the trigger level of the second cutoff control transistor advances as the charging voltage of the advance angle capacitor increases as the rotation speed increases, so the ignition position is determined by the rotation speed. progresses as the value increases.

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

Furthermore, if a bypass circuit is provided that bypasses a part of the discharge current of the advance angle capacitor through the diode and the base circuit of the first cutoff control transistor as described above, It has been confirmed through experiments that the linearity of the advance angle characteristic can be improved because the waveform of the applied signal can be made into a linearly rising waveform as shown in FIG. 4(D).

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows an embodiment of the present invention embodying the configuration of FIG. 1, and in this figure, the same parts as those in FIG. 1 are given the same reference numerals. In this embodiment, the main current control transistor switch 3 is composed of one NPN) transistor TRI, but the main current control transistor switch 3 can also be composed of two Darlington-connected transistors. transistor TR
The collector and emitter of the transistor TRI are connected to one end (in this example, one end on the non-grounded side) and the other end of the primary coil 1a, and the base of the transistor TRI is connected to the primary coil 1a which also serves as an ignition power supply coil via resistors R1 and R2. connected to one end of the Therefore, the voltage V in the direction of the arrow shown in the figure is applied to the primary coil 1a.
When e occurs, a base current flows to the transistor TR1 through the resistors R2 and R1, and the transistor TRI becomes conductive.

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

In the peak trigger circuit 402, one end of a capacitor C1 is connected to one end of the primary coil 1a via a resistor R3, and the other end of the capacitor is connected to a charging current detection capacitor whose emitter is connected to the other end of the primary coil. NPN transistor T
Connected to the base of R4. The collector of the transistor TR4 is connected to the emitter of an NPN transistor TR5, the collector of the transistor TR5 is connected to the base of the transistor TR2 through a resistor R7, and the base of the transistor TR5 is connected to the primary coil 1 through a resistor R5.
each connected to one end of a.

A diode D1 is connected between the base and emitter of the transistor TR2, and a diode D2 is connected between the base and emitter of the transistor TR4. Capacitor C1, transistor TR4.

TR5, resistors R3, R5, R7 and diodes D1, D
2 constitutes a peak trigger circuit 402.

A transistor T is connected to the connection point between the capacitor C1 and the resistor R3.
The emitter of R6 is connected, and the collector of transistor TR6 is connected to the base of transistor TR2. Further, the base of the transistor TR6 is connected to the collector of the transistor TR2 through a resistor R6. A positive feedback circuit 403 is configured by the transistor TR6 and the resistor R6.

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

The second cutoff control transistor 404 consists of an NPN transistor TR7 whose emitter is grounded, and whose collector is connected to the collector of the transistor TR2.

A diode D6 with its 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 the connection point between the advance angle capacitor 405 and the diode D3 through a resistor R8. Also, advance angle capacitor 405 and diode D
A resistor R9 is connected between the connection point with 4 and the ground, and a resistor R8
and R9 constitute an advance angle trigger circuit 406.

Further, the anode of a 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. A 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 consists of a flywheel 5 attached to the rotating shaft of an engine, a magnet 6 attached to a recess 5a provided on the outer periphery of the flywheel, and a magnet 6 attached to the outer periphery of the flywheel 5 through a predetermined gap. It consists of a stator 7 arranged opposite to each other. The stator 7 includes a substantially C-shaped iron core 8, and an ignition coil 1 consisting of a primary coil 1a and a secondary coil 1b is fitted into the iron core 8.

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. 4(A) is induced in the ignition power supply coil 1a. This voltage E consists of a negative direction voltage Enl, 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, a base current flows to the transistor TR1 through the resistors R2 and R1, and the transistor TRI becomes conductive. As a result, a short circuit current N (indicated by a broken line in FIG. 4A) flows from the primary coil 1a through the transistor switch 3. This current 11 flows across the transistor switch 3.
A voltage similar to the waveform of is generated. Further, due to the voltage across the transistor switch 3, a current flows through the resistor R3, the capacitor C1, and the pace emitter of the transistor TR4, and the capacitor CI is charged until the voltage across the transistor switch 3 reaches its peak value. At this time, a resistor R5 and a transistor T are connected from one end of the primary coil 1a.
A current flows between the pace emitter of R5 and between the collector and emitter of transistor TR4, and the transistor TR
No current flows through the base collector of 5. Therefore, at this time, no base current is applied to the transistor TR2, and the transistor TR2 is maintained in a cut-off state. When the voltage across the main current control transistor switch 3 reaches its peak, the charging current of the capacitor C1 becomes zero, and the transistor TR4 becomes cut off. At this time, a current flows from the primary coil 1a side through the resistor R5 and the base-collector of the transistor TR5, and the capacitor C1 is discharged 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. A base current flows through the transistor TR2. Therefore, the transistor TR2 becomes conductive, and the main current control transistor switch 3 is cut off. This results in 1
A high voltage is induced in the secondary coil 1a, this voltage is further boosted, and a high voltage for ignition is output from the secondary coil 1b, so that the engine is ignited. Therefore, when the engine is running at low speed, ignition occurs near a substantially constant position where the induced voltage of the primary coil (ignition power supply coil) reaches its peak.

On the other hand, the advance angle capacitor 405 is charged through the diode D3 and the diode D4 when the ignition power supply coil 1a outputs the negative direction voltage Enl.

This charging is performed until the negative direction voltage Enl reaches its peak.

When the negative direction voltage Enl passes the peak, the capacitor 405
is discharged between the resistor R8 and the pace 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 becomes conductive, cutting off the main current control transistor switch 3 and performing the ignition operation. Since the charging voltage of the capacitor 405 increases as the output voltage Vnl of the ignition power supply coil increases as the rotational speed increases, the phase (ignition position) in which the discharge current of the capacitor 405 reaches the trigger level of the transistor TR7 occurs.
advances as the rotational speed increases.

FIG. 4(B) shows the waveform of the voltage vb between the base of the transistor TR2 and ground, and FIG. 4(C) shows the waveform of the voltage Vc across the advance angle capacitor 405. Further, FIG. 4(D) shows the waveform of the voltage vd between the base of the transistor TR7 and the ground. When the engine is at low speed, the voltage vb
The peak value of is set to a predetermined trigger level v11 (for example, 0,
When the voltage reaches V), the transistor TR2 becomes conductive to perform the ignition operation.

If the trigger circuit 406 and the bypass circuit 407 by discharging the advance angle capacitor are not provided, the advance angle characteristics will be obtained using the waveform of the voltage vb.
The waveform of is a waveform with a concave portion between the peak that occurs at the position of angle θ3 and the peak that occurs at the position of angle θ0, so if the ignition position is advanced using this voltage Vb, it will not be linear. It is difficult to obtain accurate lead angle characteristics.

On the other hand, a trigger circuit 406 uses the discharge current of the advance angle capacitor 405, and a part of the discharge current is connected to the diode D.
5 and the base circuit of the transistor TR2, so that the conduction of the transistor TR7 shuts off the transistor switch 3 and performs the ignition operation. The waveform of the voltage Vd generated between the pace emitter of the transistor TR7 is a waveform that increases linearly as shown in FIG. Experiments have shown that the size increases with

In the ignition system of the present invention, the waveform voltage Vd, which linearly increases as the engine rotates, reaches the predetermined trigger level V.
Since the ignition operation is performed when the advance angle reaches 12, the ignition position advances linearly as the rotation speed increases (as shown in Figure 5, the ignition position advances linearly as the rotation speed increases.
It is possible to obtain a characteristic in which the ignition position θi linearly advances above s.

In the embodiments described above, the advance angle starting rotation speed and the slope of the advance angle characteristic can be adjusted by appropriately setting the discharge time constant of the advance angle capacitor 405. Further, the advance angle characteristics are not affected by variations in the air gap of the magnet generator provided with the ignition power supply coil, variations in the amount of magnetization of the magnet, etc.

In the above embodiment, after a spark is generated from the spark plug 1,
Depending on the combustion state of the internal combustion engine, once the spark is cut out and the voltage applied between the collector and emitter of the transistor switch 3 becomes zero or negative, the circuit operation returns to its initial state. Thereafter, the transistor switch 3 is made conductive again by the energy remaining in the magnet generator, and then performs a cut-off operation. When such a condition occurs, some of the ignition energy is dissipated within the ignition circuit, reducing spark energy.

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

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

Further, in the above embodiment, the PN junctions between the base and emitter and between the base and collector of the transistor TR5 are used instead of diodes, but these PN junctions can be replaced with individual diodes. 1 more
The anodes of the diodes may be connected to one end of the ignition power supply coil 1a through the resistor R5, and the cathodes of the diodes 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, but the ignition coil is provided outside the magnet generator, and the power generation coil provided inside the magnet generator is used as the ignition power supply coil. The present invention can also be applied to a current interrupt type ignition device in which the 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 cutoff control transistor and the second cutoff control transistor are provided to cut off the main current control transistor switch, and the ignition power supply coil an advance angle capacitor that is charged by a negative direction voltage; an advance angle trigger circuit that supplies a base current to a second cutoff control transistor using the discharge current of the advance angle control capacitor; An ignition device that can provide a sufficiently wide advance width and obtain linear advance characteristics by providing a bypass circuit that bypasses the diode and the base circuit of the first cutoff control transistor. We were able to realize this.

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

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, and Figure 2 is a block diagram showing the configuration of the present invention.
A circuit diagram showing an embodiment embodying each part in the figure, Fig. 3 is a front view of main parts showing the configuration of a generator used in an embodiment of the present invention, and Fig. 4 shows signal waveforms of each part in Fig. 2. 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... Spark plug, 3... Transistor switch for main current control, 401... First cutoff control transistor, 402...beak trigger circuit, 404
...Second cutoff control transistor, 405...Advance angle capacitor, 405...Advance angle trigger circuit, 40
7...Side circuit.

Claims (1)

[Scope of Claims] An ignition power supply coil that successively outputs a negative direction voltage and a positive direction voltage in synchronization with the rotation of the internal combustion engine; The main current control transistor switch includes a main current control transistor switch that conducts when a base current flows in response to a directional output voltage, and a switch control circuit that controls the main current control transistor switch to be in a cut-off state at the ignition timing of the internal combustion engine. In an ignition device for an internal combustion engine that obtains a high voltage for ignition by boosting the voltage induced in the ignition power supply coil by interrupting the current control transistor switch, the switch control circuit includes: when the main current control transistor is turned on, the main current control transistor A first cutoff control transistor connected to the transistor switch so as to put the switch in a cutoff state, and a collector-emitter circuit connected in parallel to the collector-emitter circuit of the first cutoff control transistor. a second cutoff control transistor that turns off the main current control transistor switch when conductive; and a second cutoff control transistor that sets the main current control transistor switch to a cutoff state when the main current control transistor switch is turned on; a peak trigger circuit that applies a trigger signal to the first cutoff control transistor to make it conductive; an advance angle capacitor; and a capacitor charger that charges the advance angle capacitor with the negative output voltage of the ignition power supply coil. a circuit, discharging the advance angle capacitor through the base circuit of the second cutoff control transistor at a constant time constant, and when the discharge current of the advance angle capacitor reaches a predetermined trigger level, the second an advance angle trigger circuit that conducts the first cutoff control transistor; and a bypass circuit that bypasses a part of the discharge current of the advance angle capacitor through a diode and a base circuit of the first cutoff control transistor. An ignition device for an internal combustion engine characterized by comprising: