JPH0445671B2 - - Google Patents

Description

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

[Prior Art] A current interrupt type ignition device for an internal combustion engine includes a main current control transistor switch that is provided in parallel with an ignition power supply coil and substantially shorts the ignition power supply coil when it is electrically connected; A semiconductor switch for cutoff control is connected to the transistor switch for main current control so as to cut off the transistor switch for main current control when the main current control transistor switch is ) and triggers a semiconductor switch for cutoff control when the main current reaches a predetermined value. There are some that use a coil to further boost the voltage to obtain a high voltage for ignition.

In this type of ignition system, in order to improve the ignition performance at low engine speeds, when the main current reaches its peak at low engine speeds, the main current control transistor switch is shut off to perform ignition operation. It is necessary to Utility Model Application No. 58-102774 and Japanese Patent Publication No. 1987-10277 proposed a method for igniting at the position where the main current reaches its peak when the engine speed is low.
There are proposals such as No. 13189.

[Problems to be Solved by the Invention] Conventionally proposed current interrupt type ignition devices connect a current detection resistor in series with the main current control transistor switch. There was a problem in that the short circuit current flowing through the control transistor switch was suppressed, resulting in poor ignition performance at low engine speeds.

As shown in JP-A-58-131357, a differentiating circuit consisting of a series circuit of a resistor and a capacitor is connected to both ends of the main current control transistor switch, and the voltage across the resistor of the differentiating circuit is An ignition device has been proposed in which a controlled trigger circuit is provided and a main current control transistor switch is controlled in accordance with the voltage across a resistor of the differentiating circuit. In this ignition device, the main current control transistor switch is made conductive while the voltage across the resistor of the differentiating circuit exceeds a predetermined value, and as the output voltage of the ignition power supply coil approaches its peak, the voltage across the resistor of the differentiating circuit increases. When the current falls below a predetermined value, the main current control transistor switch is cut off.

However, in this ignition device, the main current control transistor switch cannot maintain conduction unless the voltage across the resistor of the differential circuit exceeds a predetermined value. First, it is necessary to keep the voltage across the main current control transistor switch high to some extent. Therefore, this ignition system also requires a resistor to be connected in series with the main current control transistor switch, which poses the problem of poor ignition performance at low engine speeds.

In addition, in this ignition system, the main current control switch is cut off when the voltage across the resistor of the differential circuit drops below a predetermined value, so the position where the main current reaches its peak (the voltage across the resistor of the differential circuit The main current control transistor switch cannot be maintained in a conductive state until the main current reaches zero (zero position), and the cutoff position (ignition position) at low speeds must be set to a position before the main current peak position. do not have. Therefore, there was a problem in that the ignition operation could not be performed at the peak position of the main current when the engine was running at low speeds, and the ignition performance at low speeds could not be made sufficiently high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a current-interrupting type ignition device for an internal combustion engine that has improved ignition performance when the engine is running at low speeds.

[Means for Solving the Problems] The present invention provides an ignition power supply coil that is connected in parallel to an ignition power supply coil that induces a voltage in synchronization with the rotation of an internal combustion engine, and is conductive because a base current flows due to the output of the ignition power supply coil. Main current control transistor switch 3
and a cut-off control semiconductor switch 4 connected to the main current control transistor switch so as to turn the main current control transistor switch into a cut-off state when conductive.
and a trigger circuit 6 that triggers the cutoff control semiconductor switch to conduct at the ignition timing of the internal combustion engine, and a main current control transistor switch 3.
This is an ignition device for an internal combustion engine that obtains ignition voltage by boosting the voltage induced in the ignition power supply coil by cutting off the ignition power supply coil.

FIG. 1 is a block diagram illustrating the configuration of the present invention. In the same figure, 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, and 2 is an ignition coil 1 of the ignition coil 1 attached to a cylinder of an engine (not shown). Next are the spark plugs connected to both ends of the coil. At least the primary coil 1a of the ignition coil 1 is disposed in a generator driven by an engine, and an alternating current voltage is induced in the primary coil 1a in synchronization with the rotation of the engine. That is, in the example shown in FIG. 1, the primary coil 1a also serves as the ignition power supply coil.

A main current control transistor switch 3 is connected in parallel to both ends of the primary coil (ignition power supply coil) 1a, and this transistor switch controls the voltage Ve when a voltage Ve is induced in the ignition power supply coil 1a in the direction of the arrow shown. As a result, base current Ib flows and becomes conductive.

When a semiconductor switch 4 for cutoff control is connected between the control input terminal (base) 3a of the main current control transistor switch 3 and one end (emitter) of the main current control transistor switch 3, and the semiconductor switch 4 is turned on. Then, the supply of base current Ib to the main current control transistor switch 3 is blocked, and the transistor switch 3 becomes cut off.

Reference numeral 5 denotes a peak detection capacitor charged by the voltage Ve of the ignition power supply coil 1a in the direction of the arrow shown in the figure, and the capacitor 5 is connected between one end of the ignition power supply coil 1a and the control input terminal 6a of the trigger circuit 6. There is.

The trigger circuit 6 is, for example, as shown in FIG. 3, a trigger signal supply circuit that supplies a trigger signal to the cut-off control semiconductor switch 4 when the voltage Ve across the main current control transistor switch 3 reaches a predetermined value. The base is connected to the peak detection capacitor 5 so as to conduct the charging current of the peak detection capacitor 5 as a base current, and the trigger signal is bypassed from the cutoff control semiconductor switch when conduction occurs. Trigger control transistor switch TR4, diode D2 connected between one end of capacitor 5 and one end of the cutoff control semiconductor switch, and between the other end of the cutoff control semiconductor switch and the other end of the peak detection capacitor. The diode D1 is connected to the diode D1. Semiconductor switch 4 for cutoff control and both diodes D2, D1
A discharge circuit for the peak detection capacitor 5 is configured.

In the above configuration, when the rotating shaft of the engine is rotated and a voltage Ve is induced in the ignition power supply coil 1a in the direction of the arrow shown in the figure, a base current flows through the main current control transistor switch 3 due to the voltage Ve, and the base current flows through the main current control transistor switch 3. Switch 3 becomes conductive. Therefore, a short circuit current (main current) I1 flows from the ignition power supply coil 1a through the transistor switch 3. As the short circuit current I1 increases as the voltage Ve increases, the voltage across the main transistor switch 3 increases. A peak detection capacitor 5 is charged by the voltage across the transistor switch 3, and a charging current Ic flows through the peak detection capacitor 5. When the voltage Ve reaches its peak value, the voltage across the main transistor switch 3 also reaches its peak value,
The charging current of the peak detection capacitor 5 becomes zero. As a result, the trigger control transistor switch provided in the trigger circuit 6 enters the cutoff state, allowing a trigger signal to be applied to the cutoff control semiconductor switch 4, and the semiconductor switch 4
conduction. Therefore, the main current control transistor switch 3 is cut off, and the short circuit current I1 suddenly becomes zero. 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 the above explanation, it was assumed that the primary coil of the ignition coil 1 also serves as the ignition power supply coil, but the ignition coil is arranged outside the generator, and the ignition power supply coil is arranged inside the generator driven by the engine. 7 is provided separately from the ignition coil 1 as shown in FIG.
A circuit may be adopted in which the ignition power supply coil 7 is connected in parallel to the main current control transistor switch 3 and the primary coil 1a of the ignition coil.

[Function] As described above, the peak detection capacitor 5 charged by the voltage Ve across the main current control transistor switch 3 is provided, and the trigger control transistor switch TR4 conducts the charging current of the capacitor as a base current. When the trigger control transistor switch is cut off, the cut-off control semiconductor switch 4 is triggered to cut off the main current control transistor switch 3, so that the main current flowing through the main current control transistor switch 3 is When the charging current of the peak detection capacitor 5 reaches its peak and becomes zero, the trigger control transistor switch TR4 is cut off and the ignition operation is performed. Therefore, the ignition operation can always be performed at the peak position of the main current,
Ignition performance at low engine speeds can be improved.

Furthermore, with the above configuration, when the main current control transistor switch 3 is conductive, a small charging current corresponding to the base current of the trigger control transistor switch TR4 is detected at its peak using the voltage across the main current control transistor switch 3. If the main current control transistor switch 3 is conductive, the voltage across the main current control transistor switch 3 does not need to be so high because the ignition operation can be performed if the current can flow through the main current control capacitor 5. Therefore, there is no need to insert a resistor in series with the main current control transistor switch, which not only reduces loss and improves ignition performance at low engine speeds, but also reduces heat generation. .

Further, with the above configuration, the peak detection capacitor 5 discharges through the diode D2, the semiconductor switch 4, and the diode D1 when the cutoff control semiconductor switch 4 is turned on. Therefore, even if a high voltage is induced in the ignition power supply coil 1a when the main current control transistor switch 3 is cut off, the diode D2, the cutoff control semiconductor switch 4, and the diode D1 are connected across the peak detection capacitor 5. There is only a small voltage drop across the series circuit. Therefore, the peak detection capacitor 5 does not need to withstand the high voltage induced in the ignition power supply coil during the ignition operation, and an inexpensive capacitor with a low withstand voltage can be used as the peak detection capacitor 5.

Further, as described above, if the discharge circuit of the peak detection capacitor 5 is configured by the cutoff control semiconductor switch 4 which is conductive during the ignition operation, the peak detection capacitor 5 is caused by the high voltage induced in the ignition power supply coil 1a. This can prevent the trigger control transistor switch TR4 from being re-conducted during the ignition operation and the main current control transistor switch from being re-conducted. Therefore, by re-conducting the main current control transistor switch, it is possible to prevent part of the ignition energy from being lost and the ignition performance from being degraded.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 shows an embodiment of the present invention embodying the configuration of FIG. 1, and in the 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 connected to two NPNs connected in Darlington.
It consists of transistors TR1 and TR2.
The collector and emitter of transistor TR1 are 1
One end of the next coil 1a (in this example, one end on the ground side)
and the other end, and the base of the transistor TR2 is connected via resistors R1 and R2 to one end of a primary coil 1a which also serves as an ignition power supply coil.
Therefore, the voltage in the direction of the arrow shown in the figure is applied to the primary coil 1a.
When Ve is generated, a base current flows to the transistor TR2 through the resistors R2 and R1, and the transistor TR1 becomes conductive.

The semiconductor switch 4 for cutoff control is composed of an NPN transistor TR3, whose collector is connected to one end of the primary coil 1a via a resistor R2, and its emitter is connected to the other end of the primary coil 1a.

The peak detection capacitor 5 has a resistor hole R at one end.
3 to one end of the primary coil 1a, and the other end of the capacitor is connected to the base of an 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 transistor TR5 through a resistor R4, the collector of the transistor TR5 is connected to the base of the transistor TR3, and the base of the transistor TR5 is connected to one end of the primary coil 1a through a resistor R5. has been done. A diode D1 with its anode facing the emitter side of the transistor is connected between the base and emitter of the transistor TR4, and the connection point between the peak detection capacitor 5 and the resistor R3 and the transistor TR
A diode D2 with its anode facing the peak detection capacitor 5 side is connected between the collector of the capacitor 3 and the collector of the diode D2.

In this example, resistor R5 and transistor TR
The base-collector circuit 5 constitutes a trigger signal supply circuit that supplies a trigger signal to the cut-off control semiconductor switch 4 using the voltage across the main current control transistor switch 3, and the transistor TR4
This constitutes a trigger control transistor switch which bypasses the trigger signal from the cut-off control semiconductor switch 4 when conductive. A trigger circuit 6 is constituted by these trigger signal supply circuits and the trigger control transistor switch.

In the above embodiment, when the engine is running at low speed, when a voltage Ve is induced in the primary coil 1a of the ignition coil 1,
Due to the above operation, the transistor switch 3 becomes conductive, and the transistor switch 3 is turned on from the primary coil 1a.
A short circuit current I1 flows through. Further, due to the voltage across the transistor switch 3, a current flows through the resistor R3, the peak detection capacitor 5, and the base-emitter of the transistor TR4, and the peak detection capacitor 5 is charged. When the voltage across the transistor switch 3 exceeds the peak value, the charging current Ic of the peak detection capacitor 5
The current flows between the base and emitter of TR4, making the transistor TR4 conductive. At this time, from one end side of the primary coil 1a, a resistor R5 and a transistor TR5 are connected.
between the base emitter of the resistor R4 and the transistor
The current I2 is passed between the collector and emitter of TR4.
flows, and no current flows through the base collector of transistor TR5. Therefore, at this time, no base current is applied to the transistor TR3, and the transistor TR3 is maintained in a cut-off state. When the voltage across the main current control transistor switch 3 reaches its peak value, the peak detection capacitor 5
Since the charging current Ic of the capacitor becomes zero, the transistor TR4, which was conducting with the charging current of the capacitor as the base current, becomes cut off. At this time, a charging current flows from the primary coil 1a side through the resistor R5 and the base-collector of the transistor TR5, and a base current flows through the transistor TR3. Therefore, the transistor TR3 becomes conductive and turns off the transistor switch 3. As a result, the primary coil 1a
A high voltage is induced in the secondary coil 1b, and this voltage is further increased to output a high voltage for ignition from the secondary coil 1b, so that the engine is ignited. Therefore, when the engine speed is low, 1
Ignition occurs at a substantially constant position where the induced voltage of the next coil (ignition power supply coil) reaches its peak.

When the transistor TR3 becomes conductive, the charge in the peak detection capacitor 5 is discharged through the diode D2, the transistor TR3, and the diode D1. The high voltage induced in the primary coil 1a by the interruption of the main current control transistor switch 3 is applied to the peak detection capacitor 5, but since the transistor TR3 is conducting at this time, both ends of the peak detection capacitor 5 are The voltage is diode D
2 and D1 forward voltage drop and the transistor
It is maintained at a low voltage corresponding to the sum of the collector-emitter saturation voltage of TR3. Therefore, as the peak detection capacitor 5, one having a low withstand voltage can be used.

Further, in the above embodiment, when the peak detection capacitor 5 is recharged by the high voltage induced in the primary coil 1a of the ignition coil when the ignition operation is performed, the transistor TR4 is re-conducted and the transistor TR3 is turned on. As a result, the main current control transistor switch 3 becomes conductive again, and a portion of the ignition energy is lost. In the present invention, in order to prevent this, the discharge circuit of the peak detection capacitor 5 is activated by the semiconductor switch 4 for cutoff control, which is in a conductive state when the transistor switch 3 for main current control is cut off, and the diodes D2 and D1. The peak detection capacitor is configured to prevent the peak detection capacitor from being recharged by the induced voltage of the primary coil 1a.

When the engine is running at high speed, the charging current of the peak detection capacitor 5 is flowing, and the current I2 is flowing between the base and emitter of the transistor TR5.
The voltage between the emitter of TR3 and the transistor
When the voltage between the base and emitter of TR3 is reached, a base current flows through the transistor TR3, and the transistor TR3 becomes conductive. Therefore, when the engine is running at high speed, the voltage between the base of transistor TR5 and the emitter of transistor TR3 is
Ignition occurs at the position where the voltage between the base emitter of TR3 is reached, and this ignition position advances as the engine speed increases. Therefore, in the above embodiment, the characteristics of the ignition position θ with respect to the engine rotational speed N (rpm) are as shown in the curve shown in FIG. 5, and the ignition timing is constant when the engine is running at low speed.
In the medium and high speed range of the engine, the ignition timing is advanced. In Fig. 5, TDC indicates the top dead center of the engine.

Further, in the above embodiment, the characteristic of the ignition high voltage V2 obtained in the secondary coil of the ignition coil 1 with respect to the rotational speed N is a curve as shown in FIG.

In the above embodiment, the transistor TR3 is used as the semiconductor switch 4 for cutoff control, but the transistor TR3 can also be replaced with a thyristor.

In the embodiment described above, diodes D1 and D2 are necessary for discharging the peak detection capacitor 5, but these diodes also serve to increase the switching speed of the transistor switch 3. That is, by providing the diodes D1 and D2, when the main transistor switch 3 is cut off, positive feedback is applied to the circuit of the transistors TR4, TR5, and TR3, so that the cut-off speed of the transistor switch 3 can be increased, and the ignition performance can be improved. can be improved.

Furthermore, in the above embodiment, the transistor TR
Although the currents I2 and I3 are made to flow using the diode characteristics between the base and emitter and between the base and collector of the transistor TR5, the transistor TR5 can also be replaced with diodes D4 and D5 as shown in FIG. Also, instead of using two diodes like this,
Using one diode, the anode of the one diode is connected to the resistor R5, and the cathode is connected to the resistor R5.
4 and the base of the transistor TR3.

[Effects of the Invention] As described above, according to the present invention, a peak detection capacitor charged by the voltage across the main current control transistor switch is provided, and trigger control is performed to conduct the charging current of the capacitor as a base current. A transistor switch is provided for
Since the semiconductor switch for cut-off control is triggered when the transistor switch for trigger control is cut off, the main current flowing through the transistor switch for main current control reaches its peak and the charging current of the peak detection capacitor becomes zero. When the trigger control transistor switch is cut off, the ignition operation can be performed. Therefore, the ignition operation can always be performed at the peak position of the main current, and the ignition performance at low speeds of the engine can be improved.

Further, according to the present invention, when the main current control transistor switch is turned on, a small charging current corresponding to the base current of the trigger control transistor switch is applied to the peak detection capacitor by the voltage across the main current control transistor switch. If the current can flow, ignition can be performed, so the voltage across the main current control transistor switch when it is conducting does not need to be that high, and there is no need to insert a resistor in series with the main current control transistor switch. . Therefore, there is an advantage that not only can loss be reduced and ignition performance at low speeds of the engine be improved, but also that heat generation can be reduced.

In particular, according to the present invention, a semiconductor switch for cutoff control and a capacitor for peak detection, which are conductive when an ignition operation is performed, are connected via a diode, and the semiconductor switch for cutoff control and the diode discharge the capacitor for peak detection. Now that the circuit has been configured, the voltage applied to both ends of the peak detection capacitor when a high voltage is induced in the ignition power supply coil due to the cutoff of the main current control transistor switch is applied to both ends of the series circuit of the diode and the cutoff control semiconductor switch. can be limited to a low voltage corresponding to the voltage drop that occurs in the Therefore, an inexpensive capacitor with low withstand voltage can be used as the peak detection capacitor.

Further, according to the present invention, the discharge circuit consisting of the semiconductor switch for cut-off control and the diode prevents the peak detection capacitor from being recharged by the high voltage induced in the ignition power supply coil. It is possible to prevent the main current control transistor switch from being re-conducted during the process, causing a part of the ignition energy to be lost, and from deteriorating the ignition performance.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic configuration of the present invention when the primary coil of the ignition coil also serves as the ignition power supply coil, and Fig. 2 is a basic diagram of the present invention when the ignition coil is provided separately from the ignition coil. 3 and 4 are circuit diagrams showing different embodiments of the present invention, and FIG. 5 shows the ignition characteristics obtained with the embodiments of FIGS. 3 and 4. It is a line diagram. DESCRIPTION OF SYMBOLS 1... Ignition coil, 1a... Ignition power supply coil (primary coil), 2... Ignition coil, 3... Transistor switch for main current control, 4... Semiconductor switch for cutoff control, 5... Capacitor for peak detection, 6... Trigger circuit, TR1~TR5...Transistor, R1~R
5...Resistor, D1-D4...Diode.

Claims (1)

[Scope of Claims] 1. A main current control transistor switch that is connected in parallel to an ignition power supply coil that induces a voltage in synchronization with the rotation of an internal combustion engine, and conducts when a base current flows by the output of the ignition power supply coil. 3, a semiconductor switch for shutdown control 4 connected to the main current control transistor switch so as to turn off the main current control transistor switch when conductive, and a semiconductor switch for shutdown control that triggers the semiconductor switch for shutdown control at the ignition timing of the internal combustion engine. an ignition device for an internal combustion engine which obtains a high voltage for ignition by boosting the voltage induced in the ignition power supply coil by cutting off the main current control transistor switch, The trigger circuit 6 includes a peak detection capacitor 5 that is charged by the voltage across the control transistor switch 3, and the trigger circuit 6 operates to detect the cutoff control when the voltage across the main current control transistor switch 3 reaches a predetermined value. a trigger signal supply circuit for supplying a trigger signal to a semiconductor switch; a base connected to the peak detection capacitor so that the charging current of the peak detection capacitor 5 is used as a base current; and when conductive, the trigger signal is cut off. a trigger control transistor switch TR4 provided to bypass the control semiconductor switch 4; a diode D2 connected between one end of the peak detection capacitor 5 and one end of the cutoff control semiconductor switch 4; a diode D1 connected between the other end of the semiconductor switch 4 for cutoff control and the other end of the capacitor 5 for peak detection; An ignition device for an internal combustion engine, characterized in that a discharge circuit for a detection capacitor 5 is configured.