JPS5819334Y2 - Ignition system for internal combustion engines - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an ignition device for an internal combustion engine.

Generally, in an internal combustion engine, the ignition position is advanced as the rotational speed (rpm) increases, but in a two-stroke internal combustion engine, it is better to delay the ignition position in the high speed region due to temperature and intake efficiency. is known to increase.

Furthermore, in a four-stroke engine, it may be necessary to delay the ignition position in a high-speed region in order to prevent overspeed.

Therefore, the applicant first connected the collector-emitter circuit of a transistor in parallel via a resistor to the output terminal of a signal source that determines the operating position (ignition position) of the semiconductor switch for primary current control, so that the rotational speed of the engine would match the set speed. An internal combustion engine ignition system has been proposed in which the collector-emitter impedance is reduced by applying a signal to the base of the transistor when the impedance is exceeded.

This device uses a voltage comparator to compare the speed detection voltage, which changes depending on the engine rotation speed detected by the rotation speed detection circuit, with a reference voltage corresponding to the set speed, and detects when the rotation speed exceeds the set speed. When this happens, the comparator applies a signal to the base of the transistor to control the conduction of the transistor.

If the signal is intercepted in this way, a part of the signal source will be shunted through the series circuit of the transistor's collector-emitter circuit and the resistor when the engine speed increases, without being affected by variations in the characteristics of the transistor elements. Therefore, the phase in which the output of the signal source reaches the trigger level of the primary current control semiconductor switch is delayed, and a desired retard characteristic can always be obtained during high-speed rotation.

By the way, a characteristic of commonly used voltage comparators is that when the power supply voltage of the comparator is lower than the operating voltage, the comparator sometimes malfunctions in that it outputs a signal from the output terminal regardless of the input signal without becoming inoperable. has been confirmed through testing.

Conventional devices use the rectified output of the rotation speed detection coil included in the rotation speed detection circuit as the power supply voltage of the comparator, so the power supply voltage of the comparator may fall below the operating voltage when the engine rotates at low speed. When the engine is turned on, the transistor becomes conductive, causing a malfunction in which the ignition position is delayed, resulting in unstable engine operation.

In order to overcome these drawbacks, it may be possible to increase the number of turns of the rotation speed detection coil to obtain sufficient voltage to drive the comparator even during low speed rotation, but this will inevitably result in Since the capacitance of components such as Zener diodes used in the rectifier circuit increases, power loss also increases, which has the disadvantage of increasing the influence on the ignition operation.

An object of the present invention is to provide an internal combustion engine ignition device that eliminates the above-mentioned drawbacks by providing a switch that electrically disconnects the signal source from the collector-emitter circuit of the transistor when the power supply voltage of the comparator is lower than the operating voltage. It is in.

The present invention will be explained in detail below with reference to the illustrated embodiments.

FIG. 1 shows an embodiment in which the present invention is applied to a capacitor charge/discharge type ignition device for an internal combustion engine.

In the figure, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b, and a spark plug 2 attached to a cylinder of an engine is connected to both ends of the secondary coil 1b of the ignition coil 1.

A capacitor 3 is connected in series to the primary coil 1a of the ignition coil 1, and a thyristor 4 as a semiconductor switch for primary current control is connected to both ends of the series circuit of the primary coil 1a and the capacitor 3 with the anode on the capacitor 2 side. connected in parallel.

An exciter coil 6 is connected in parallel to both ends of the series circuit of the primary coil 1a and the capacitor 3 via a diode 5 whose cathode is on the side of the capacitor 3, and a diode 7 opposite to this thyristor is connected to both ends of the thyristor 4. are connected in parallel.

A resistor 8 is connected in parallel between the gate and cathode of the thyristor 4, and a capacitor 9 and a resistor 10 are connected across the resistor 8.
A thyristor 11 whose anode is on the cathode side of the thyristor 4 is connected in parallel through a series circuit.

A Zener diode 12 is connected in parallel between the anode and gate of the thyristor 11 with the anode facing the gate of the thyristor 11, and a resistor 13 is connected in parallel between the gate and cathode of the thyristor 11.

The connection point between the resistor 13 and the cathode of the thyristor 11 is connected to the anode of the diode 14, and the cathode of the diode 14 is connected to the other end of the signal coil 15, which has one end connected to the connection point between the exciter coil 6 and the diode 5. ing.

The above-mentioned parts constitute a capacitor charging/discharging type ignition circuit.

In order to detect the rotational speed of the engine, a rotational speed detection coil 16 is provided, one end of which is connected to the connection point between the anode of the diode 14 and the resistor 13.

A series circuit consisting of a diode 17 with its anode on the other end of the detection coil 16, a resistor 18, and a capacitor 19 is connected in parallel to both ends of the detection coil 16, and a resistor 20 is connected in parallel to both ends of the capacitor 19. There is.

A diode 21 whose anode is commonly connected to the anode of the diode 17 and a resistor 2 are connected to both ends of the detection coil 16.
A smoothing capacitor 23 is connected in parallel through the capacitor 2, and a Zener diode 24 is connected in parallel to both ends of the capacitor 23.

A potentiometer type variable resistor 2 is connected to both ends of the capacitor 23.
5 are connected in parallel, and the intermediate terminal 25 of this variable resistor 25
1 is connected to one input terminal of the comparator 26.

The other input terminal of the comparator 26 is connected to the resistor 18 and the capacitor 1.
9, and the output terminal of the comparator 26 is connected to the base of an npn transistor 27 as a semiconductor switch for controlling the ignition position.

The emitter of the transistor 27 is connected to one end of the variable resistor 25 on the capacitor 23 side, and the collector is connected to the emitter of a transistor 29 as a malfunction prevention switch via a resistor 28 as a current limiting element.

The base of the transistor 29 is connected to the capacitor 23 and the resistor 2 through a series circuit of a resistor 30 and a Zener diode 31.
2 and the variable resistor 25, and its collector is connected to the cathode of the thyristor 4.

In the above device, the exciter coil 6, diode 5, and capacitor 3 constitute a power supply circuit that supplies energy to flow the primary current to the ignition coil, and the signal coil 15 serves as a signal source for determining the ignition position. It is configured.

In addition, the signal coil 1 is
A waveform shaping circuit is configured to convert the signal given from 5 into a pulse, and the signal circuit is constituted by the signal coil 15 and this waveform shaping circuit.

Furthermore, a detection coil 16, a diode 17, a resistor 18.2
0 and a capacitor 19 constitute a rotational speed detection circuit, and a detection coil 16, a diode 21 . A reference voltage generation circuit is composed of a resistor 22, a capacitor 23, a Zener diode 24, and a variable resistor 25.

The rotational speed detection circuit, the reference voltage generation circuit, the comparator 26, the transistor 27, and the resistor 28 constitute an ignition position control circuit, and the transistor 29 constitutes a malfunction prevention switch.

In the above device, the exciter coil 6, the signal coil 15, and the detection coil 16 are power generation coils arranged in a magnetic alternator that rotates in synchronization with the internal combustion engine; According to the phase relationship shown by the arrow in the figure, the AC voltage V6. Induced by VI5 and V16.

Now the voltage in the direction of the solid arrow shown in the exciter coil 6 ■6
When this is induced, the capacitor 3 is charged to the polarity shown through the diode 5 and the primary coil 1a.

Next, when a voltage V15 in the direction of the dashed arrow shown in the figure is induced in the signal coil 15 and the exciter coil 6, the signal coil 15
The capacitor 9 is charged to the polarity shown in the figure through the following sequence: -> the generator coil 6 -> the resistor 8 -> the capacitor 9 -> the resistor 10 -> the diode 14 -> the signal coil 15.

When the terminal voltage of this capacitor 9 exceeds a certain value, the constant voltage diode 12 becomes conductive, a signal is applied to the gate of the thyristor 11, and the thyristor 11 becomes conductive.

When the thyristor 11 becomes conductive, the charge in the capacitor 9 is discharged along the path of the resistor 8 -> the thyristor 11 -> the resistor 10 -> the capacitor 9, and a pulse-like voltage appears across the resistor 8.

This voltage provides an ignition signal for the thyristor 4, causing the thyristor 4 to conduct.

Therefore, the charge in the capacitor 3 is discharged through the thyristor 4 and the primary coil 1a, and a high voltage is induced in the secondary coil 1b, causing ignition.

As the rotational speed of the engine increases, the voltage induced in the signal coil 15 and the exciter coil 6 increases, so the phase at which the terminal voltage of the capacitor 9 reaches a level that makes the Zener diode 12 conductive progresses, and an ignition signal is given to the thyristor 4. The phase of the ignition is advanced and the ignition position is advanced.

Further, in the above device, when a voltage in the direction of the solid arrow shown in the figure is induced in the detection coil 16, the capacitor 19 is charged to the polarity shown in the figure at a constant time constant through the diode 17 and the resistor 18.

The charge on the capacitor 19 is discharged through the resistor 20 with a constant time constant, and the terminal voltage of the capacitor 19 decreases at a constant rate of change.

When the rotational speed of the engine is low and the interval between charging the capacitor 19 is long, the time during which the capacitor 19 can be discharged becomes longer, so that the terminal voltage of the capacitor 19 decreases to zero due to the above-mentioned discharge.

When the rotational speed of the engine increases and the interval for charging the capacitor 19 becomes shorter, the capacitor 19 is recharged before it is fully discharged, so the terminal voltage of the capacitor 19 no longer becomes zero, and the voltage Es across the capacitor 19 becomes Increases in proportion to rotation speed.

Therefore, this voltage Es can be used as a speed detection voltage.

The output of the detection coil 16 is still connected to the diode 21 and resistor 22.
, a capacitor 23, and a Zener diode 24, the voltage is rectified and made into a constant voltage, and this constant voltage is divided by a variable resistor 25 to create a reference voltage corresponding to the set rotation speed at which to start retarding the ignition position. Er is created.

The speed detection voltage Es and the reference voltage Er are input to the comparator 26.

Further, this constant voltage is inputted to the base of the transistor 29 through a series circuit of a resistor 30 and a Zener diode 31.

Although not shown, the constant voltage described above is used as the power supply voltage of the comparator 26.

The Zener voltage of the Zener diode 31 is equal to the emitter voltage of the transistor 29 and the Zener diode 3.
The Zener voltage of the Zener diode 24 is set to be equal to the Zener voltage of the Zener diode 24.

Therefore, when the rotational speed of the engine is high and the terminal voltage of the capacitor 23 becomes the Zener voltage, the base current flows to the transistor 29 through the series circuit of the resistor 30 and the Zener diode 31, and this transistor becomes conductive. ing.

In this state, when the engine speed exceeds the set rotation speed N1, the speed detection voltage Es exceeds the reference voltage Er, so the comparator 26 outputs a set speed detection signal, which causes a base current to flow through the transistor 27. The transistor also becomes conductive.

Therefore, since the transistors 27 and 29 are both conductive, the resistor 28 is connected in parallel to the signal coil 15, and part of the signal supplied from the signal coil 15 to the waveform shaping circuit 29 through the exciter coil 6 is transmitted through this resistor. 28.

Therefore, in the waveform shaping circuit 29, the phase in which the capacitor 9 reaches the Zener voltage of the Zener diode 12 is delayed, the phase in which the ignition signal pulse is applied to the thyristor 4 is delayed, and the ignition position is delayed.

If the engine speed is below the set speed, the comparator 26
Since the transistor 27 does not output a signal, the transistor 27 is in a cutoff state, and even if the l transistor 29 is in a conductive state, it does not affect the ignition operation in any way.

When the rotation speed of the engine is low and the terminal voltage of the capacitor 23 is lower than the Zener voltage of the Zener diode 24, the terminal voltage of the capacitor 23 is lower than the Zener diode 3.
Since the Zener voltage is less than 1, no base current flows through the transistor 29, and this transistor is in a cut-off state.

Therefore, when the power supply voltage of the comparator 26 is lower than the operating voltage, even if the comparator 26 outputs a signal due to a malfunction of the comparator 26 and current flows through the base of the transistor, the signal source 15 Since a part of the signal is not bypassed through the resistor 28, it is possible to prevent the ignition position control circuit from malfunctioning when the engine rotates at low speed.

In the above device, since the transistor 27 performs a switching operation, the above-mentioned delay in the ignition position occurs in stages.
The characteristics of the ignition advance angle (advance angle from the top dead center of the piston to the ignition position) α with respect to the rotational speed N (rpm) are shown in FIG.

In the above embodiment, only one rotation speed at which the ignition position is delayed can be set, but by modularizing the part surrounded by the chain line 30 in FIG. 1 and combining two or more of these modules, two or more different rotation speeds can be set. The ignition position can be retarded step by step, or the ignition position can be retarded and then advanced again.

Further, although a transistor is used as the malfunction prevention switch, other suitable controllable semiconductor switches may be used in place of the transistor, and electromagnetic switches such as relays may also be used.

Furthermore, the collector-emitter circuit of transistor 29 may be connected between the emitter of transistor 27 and the anode of Zener diode 24.

Further, the ignition device is not limited to the capacitor charging/discharging type device described above, but the present invention can be applied to any ignition device whose ignition position is determined by the output of a signal source.

As described above, according to the present invention, the malfunction prevention switch, which is cut off when the power supply voltage of the comparator is below the operating voltage and becomes conductive when it is above the operating voltage, is connected to the signal source and the ignition position control semiconductor. Since it is provided between the switch and the switch, it is possible to prevent the ignition position from being delayed due to malfunction of the comparator when the rotational speed of the engine is low and the power supply voltage of the comparator is below the operating voltage.

[Brief explanation of drawings]

Fig. 1 is a connection diagram showing one embodiment of the present invention, and Fig. 2 is a connection diagram showing an embodiment of the present invention.
FIG. 3 is a diagram showing an example of advance angle vs. rotational speed characteristics obtained by the embodiment shown in the figure. 1... Ignition coil, 2... Spark plug, 3... Condenser, 4... Thyristor (semiconductor switch for primary current control), 6... ...
・Exciter coil, 15...Signal coil, 1
6...detection coil, 29...condenser, 17゜21...diode, 18,20
, 22.30... Resistor, 23... Capacitor, 24.31... Zener diode,
25...variable resistor, 26...comparator,
27... Transistor (semiconductor switch for ignition position control), 28... Current control element, 29...
...Transistor (malfunction prevention switch).

Claims (1)

[Scope of utility model registration request] an ignition coil, a power supply circuit that supplies energy for causing a primary current to flow through the ignition coil, and a signal circuit that includes a signal source that generates a signal for determining the ignition position in synchronization with the rotation of the internal combustion engine; an ignition circuit consisting of a primary current control semiconductor switch that is operated by a signal given from a signal circuit to suddenly change the primary current of the ignition coil; and a speed detection voltage that generates a speed detection voltage that changes in accordance with the rotational speed of the internal combustion engine. A rotational speed detection circuit, a reference voltage generation circuit that generates a reference voltage corresponding to a set speed, and a power supply circuit that compares the speed detection voltage with a reference voltage to determine whether the speed detection voltage corresponds to the set speed. a comparator that outputs a set speed detection signal when it detects that the reference voltage has been exceeded; a semiconductor switch for ignition position control that is electrically connected by the set speed detection signal; and a semiconductor switch that is connected in series to the semiconductor switch for ignition position control. an ignition position control circuit comprising a current control element connected to the ignition position control circuit, and a series circuit of the ignition position control semiconductor switch and the current limiting element is provided in parallel with the signal source. In the device, a malfunction prevention switch controlled to change from a cutoff state to a conduction state when the power supply voltage of the comparator exceeds the operating voltage of the comparator is connected to the ignition position control semiconductor switch and the current limiting element. An ignition device for an internal combustion engine, characterized in that it is connected in series with a series circuit.