JPS6220382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine that retards the ignition position when the engine speed reaches a predetermined value.

Generally speaking, in internal combustion engines, it is necessary to advance the ignition position as the rotational speed (rpm) increases in the medium and high speed range, but some engines require a certain amount of advance in order to ensure good operation. It may be necessary to retard the ignition position in the region above the rotational speed. Furthermore, in order to prevent the engine from over-speeding, the ignition position is retarded at a set rotation speed. In this way, as an ignition device for an internal combustion engine that retards the ignition position at a predetermined rotation speed, a transistor switch is connected in parallel to a signal source that provides a control signal to a semiconductor switch that controls the primary current of the ignition coil. There is a device in which the ignition position is delayed by connecting the transistor switch to conduction at a set rotation speed and bypassing a part of the control signal from the semiconductor switch. In this ignition system, a speed detection circuit consisting of a capacitor charged by the output of a generator driven by the engine and a discharge circuit that discharges this capacitor is used as the circuit that supplies the base current to the transistor switch. When the output of the speed detection circuit reaches a set value, a base current is applied to the transistor switch. however,
With this configuration, the transistor switch first enters the active region at the set rotation speed, its internal resistance gradually decreases, and then enters the saturation region and becomes conductive, so the engine ignition position remains at the set rotation speed. There was a drawback that the rotation speed at which the retardation started was not clearly determined, as the lag would gradually start near the engine.
Furthermore, speed detection circuits that utilize charging and discharging of capacitors are directly affected by the output of the generator, and therefore have the disadvantage that the retardation characteristics are directly affected by fluctuations in the output of the generator.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ignition system for an internal combustion engine in which the retardation starting rotation speed can be clearly determined and the output of the generator does not directly affect the retardation characteristics.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ignition device for an internal combustion engine according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
In the figure, reference numeral 1 denotes an exciter coil provided in a magnet generator that rotates synchronously with the internal combustion engine. One end of the exciter coil 1 is connected to one end of a capacitor 3 via a diode 2, and the other end of the capacitor 3 is connected to one end of the primary coil 4a of the ignition coil 4 on the non-grounded side. Also connected to one end of the capacitor 3 is the anode of a thyristor 5, which serves as a primary current control semiconductor switch that controls the primary current of the ignition coil, and the cathode of the thyristor 5 is grounded. Secondary coil 4b of ignition coil 4
A spark plug 6 attached to the cylinder of the engine is connected to both ends of the spark plug 6, and the capacitor 3, the ignition coil 4, the thyristor 5, and the spark plug 6 constitute an ignition circuit 7 that uses the exciter coil 1 as an ignition power source. . This ignition circuit is known as a capacitor discharge type circuit, and causes a large magnetic flux change in the iron core of the ignition coil by discharging the charge charged by the exciter coil 1 through the thyristor 5 to the primary coil 4a. A high voltage is induced in the secondary coil 4b, and this high voltage causes the spark plug 6 to generate a spark. In the present invention, the configuration of this ignition circuit part is arbitrary, and the ignition operation is performed by controlling the primary current of the ignition coil 4 by a semiconductor switch for primary current control to suddenly change the primary current at the ignition position. Any circuit may be used as long as it can do this. For example, a circuit that performs ignition by cutting off the current flowing through the primary coil of the ignition coil with a semiconductor switch such as a transistor at the ignition position, or a circuit that performs the ignition operation by cutting off the current flowing through the primary coil of the ignition coil with a semiconductor switch such as a transistor. It is also possible to use an ignition circuit in which the ignition circuit and the exciter coil are connected in parallel and the ignition operation is performed by switching the semiconductor switch from the conductive state to the cut-off state at the ignition position.

In the ignition circuit 7, the conduction position of the thyristor (semiconductor switch for primary current control) 5 is the ignition position. The ignition position can be controlled by controlling according to the number (rpm). Therefore, in the present invention, a control circuit 8 is provided, and this control circuit sends a control signal (ignition signal) to the thyristor 5.
is given. The control circuit 8 of this embodiment includes a control power source 9 that utilizes the output of the exciter coil 1 in the direction of the dashed arrow shown in the figure (hereinafter referred to as negative direction output). The control power source 9 includes a diode 10 connected in series to the exciter coil 1 with its anode grounded, a thyristor 11 connected in parallel to the diode 10 with its cathode grounded, and a resistor 12 connected in parallel between the gate and cathode of the thyristor 11. , a Zener diode 13 connected in parallel between the anode gate of the thyristor 11, and an exciter coil 1.
The diode 14 has an anode connected to the connection point between the diode 10 and the diode 10, and a power supply capacitor 15 connected between the cathode of the diode 14 and ground. Exciter coil 1 and diode 1
A diode 16 whose anode is grounded is connected in parallel to both ends of the series circuit with 0. In this control power supply, the negative direction output of the exciter coil 1 connects the capacitor 15 through the diode 14.
is charged to the polarity shown. Exciter coil 1
When the negative output of the exciter coil 1 reaches a value that causes the Zener diode 13 to break down, the thyristor 11 becomes conductive, so that the negative output of the exciter coil 1 is short-circuited through the thyristor 11 and the diode 16. Therefore, the charging voltage of the capacitor 15 is limited to a certain voltage determined by the Zener voltage of the Zener diode 13.

The drain of a field effect transistor (hereinafter referred to as FET) 17 is connected to one end of the non-grounded side of the power supply capacitor 15, and the source of the FET 17 is connected to the anode of a diode 19 through a variable resistor 18. The anode of diode 19 is
Connected to the gate of FET17, diode 19
An ignition position control capacitor 20 is connected between the cathode and ground. The FET 17 and the variable resistor 18 constitute a constant current circuit, and this constant current circuit and the diode 19 connect the capacitor 1
A charging circuit that charges the capacitor 20 at a constant current with a charge of 5 is configured. The cathode of a Zener diode 22 is also connected to the non-grounded terminal of the capacitor 15 through a resistor 21, and the anode of the Zener diode 22 is grounded. resistance 21
The Zener diode 22 and the Zener diode 22 constitute a reference voltage generation circuit that generates a reference voltage, and the reference voltage V _r obtained across the Zener diode 22 and the terminal voltage of the capacitor 20 are applied to the voltage comparator 2
3 is entered. Comparator 23 is capacitor 2
The terminal voltage V _c of the capacitor 20 is compared with the reference voltage V _r and the terminal voltage V _c of the capacitor 20 is equal to or higher than the reference voltage V _r (V
_c ≧V _r ), the potential of the output terminal 23a of the interval comparator 23 becomes high level. Output terminal 23a of comparator 23 is diode 2
4 to the gate of the thyristor 5, and allows supply of a control signal to the thyristor 5 when the potential of the output terminal 23a is at a high level.

A signal coil 25 is provided to determine the ignition position when the engine is running at low speed, and to determine the retard angle width and the advance angle width. This signal coil 25 is arranged in a signal generator that rotates synchronously with the engine, and as shown in FIG. 2C, a signal v _s1 of one cycle per engine revolution,
v Generate _S2 . The horizontal axis θ in Figure 2 is the top dead center of the engine.
It shows the rotation angle with TDC as the reference position, and the peak position θ ₁ of the positive half-cycle signal v _s2 generated after the signal coil 25 coincides with the ignition position when the engine is running at low speed. . Also, the negative direction signal v generated first from this peak position θ ₁
The width of _s1 to the rising position θ ₂ | θ ₁ - _{θ 2} | corresponds to the advance width of the ignition position, and the width of the negative direction signal v _s1 |
θ ₃ −θ ₂ | corresponds to the retard width in the region of the set rotation speed or higher. A signal generator that generates such a signal is constructed by extending a part of the rotor magnetic pole of a flywheel magnet generator attached to the output shaft of the engine to the outer periphery of the flywheel, and attaching a signal coil to the signal magnetic pole. Those with signal generators wound around an iron core facing each other,
A known signal generator is used, such as one in which an inductor is formed in the boss part of the rotor of a flywheel magnet generator, and a signal generator having a permanent magnet in the middle of the magnetic path is opposed to the inductor. be able to.

One end of the signal coil is grounded, and its non-grounded terminal is connected to the thyristor 5 via a diode 26.
connected to the gate. A resistor 27 is connected in parallel between the gate and cathode of the thyristor 5. The signal coil 25 is connected so that its non-grounded terminal has a positive potential when the positive direction signal v _s2 is generated, and a control signal is directly given to the thyristor 5 by the positive direction signal v _s2 of the signal coil 25. It's getting old.

A voltage dividing circuit consisting of a series circuit of resistors 28 and 29 is connected in parallel to both ends of the signal coil 25 , and the output of the signal coil 25 (voltage at both ends of the resistor 29 ) divided by this voltage dividing circuit is applied to the thyristor 30 . It is applied between the gate and cathode. Thyristor 3
0 is connected to the non-grounded terminal of the capacitor 20, and its cathode is connected to the grounding point.
Resistors 28, 29 and thyristor 30 constitute a reset circuit that discharges capacitor 20 and resets its terminal voltage. The resistance values of the resistors 28 and 29 are set so as to give an ignition signal to the thyristor 30 substantially at the same time when the positive direction signal of the signal coil 25 rises at an angle _θ3 . Therefore, the thyristor 30 becomes conductive at approximately the angle θ ₃ and instantly discharges the capacitor 20. Therefore, the terminal voltage of the capacitor 20 has a waveform as shown in FIG. 2D, which becomes approximately zero at this angle θ ₃ and then rises at a constant slope.

The section in which a control signal is given to the thyristor 5 by a signal other than the positive direction signal of the signal coil 25 is defined as the section θ ₂ to θ in which a negative direction signal is generated in the signal coil 25.
₃ , a transistor 31 is provided as a semiconductor switch for setting the ignition position control width, the emitter of this transistor 31 is grounded, and the collector is connected to the non-ground terminal of the power supply capacitor 15 through a resistor 32. There is. The base of the transistor 31 is connected to the non-ground terminal of the power supply capacitor 15 via a resistor 33 and to the non-ground terminal of the signal coil 25 via a diode 34. Also transistor 3
A diode 35 is connected in parallel between the base and emitter of No. 1 with its anode on the emitter (ground) side. In the section where a positive direction signal is induced in the signal coil 25 and the section where the output of the signal coil 25 is zero, the transistor 31 is in a conductive state due to the base current applied from the capacitor 15 side through the resistor 33, and a negative signal is applied to the signal coil 25. During the period in which the direction signal is generated, the base and emitter of the transistor 31 is reverse biased by this negative direction signal, so that the transistor 31 is turned off. Therefore, the collector-emitter voltage of the transistor 31 has a waveform that is at a high level only in the section from θ ₂ to _{θ 3} where the negative direction signal v _s1 is generated in the signal coil 25, as shown in FIG. 2E. Engine rotation speed (rpm)
In the low speed region where the rotation angle θ is low, the negative direction signal of the signal coil 25 does not reach the level that cuts off the transistor 31. In this low speed region, the collector-emitter voltage of the transistor 31 is
remains at a low level over the entire range.

The transistor 31 is connected to the resistor 3 from the control power source 9.
2 and the diode 24 to determine the period in which the control signal is applied to the thyristor 5, and when the transistor 31 is in the cut-off state and the comparator
The resistor 32 and diode 2 are connected from the control power supply 9 side only when the potential of the output terminal 23a is at a high level.
A control signal is applied to the thyristor 5 through the thyristor 4.

Therefore, in the above embodiment, the thyristor 5
The control signal is given to (a) signal coil 25.
(b) when the transistor 31 is in the cutoff state and the output of the comparator 23 is at a high level.

Next, the operation of the above embodiment will be explained. Assuming that the magnet generator in which the exciter coil 1 is installed has four poles, two cycles of voltage are induced in the exciter coil 1 per one revolution of the engine, as shown in FIG. 2A. A part of the negative half cycle of the output of the exciter coil 1 (the part indicated by the dashed line in FIG. 2A above the level that makes the Zener diode 13 conductive)
6, the output voltage waveform of the exciter coil 1 becomes an asymmetrical waveform. When a positive output is generated in the exciter coil 1 at a position an angle θ ₀ before the top dead center TDC of the engine, the capacitor 3 is charged through the diode 2 to the polarity shown. As a result, the terminal voltage of the capacitor 3 increases as shown in FIG. 2B. Capacitor 3 is
It is also slightly charged by the second positive output of the exciter coil 1, which occurs at the angle θ' ₀ before top dead center.

On the other hand, the signal coil 25 generates a negative direction signal v _s1 at a position of angle θ ₂ before top dead center, which is set near the fall of the second positive direction output of the exciter coil 1, and then at a position of angle θ ₃ . A forward direction signal v _s2 is generated. At low engine speeds, signal coil 2
Since the negative direction signal v _s1 output from the transistor 5 does not reach a level that can cut off the transistor 31, the transistor 31 is in a conductive state. Therefore, when the engine is running at low speed, no control signal is applied to the thyristor 5 from the control power supply 9 through the resistor 32 and the diode 24, and all current flowing from the control power supply through the resistor 32 is bypassed from the thyristor 5 through the transistor 31. Ru. Then the angle θ ₃
When the positive direction signal v _s2 of the signal coil ₂₅ generated by The coil 4a is caused to discharge. Therefore, the ignition position θ _i in the low speed region where the engine speed N is between N ₀ and _{N 1} is at an angle θ ₁ from the top dead center as shown in FIG.
The position is further advanced.

When the engine rotational speed N reaches the set value _N1 , the negative direction signal output from the signal coil 25 causes the angle _θ2 to change.
The transistor 31 is then cut off. At this time, since the terminal voltage V _c of the capacitor 20 is already larger than the reference voltage V _r , the comparator 23
The potential of the output terminal 23a of the thyristor 5 is at a high level, and the control signal is allowed to be supplied to the thyristor 5. Therefore, at the angle θ ₂ , the transistor 31 is cut off and at the same time the resistor 3 is disconnected from the control power supply 9.
A control signal is applied to the thyristor 5 through the thyristor 2 and the diode 24, and ignition is performed at this angle _θ2 . That is, the ignition position θ _i advances in steps from the position at the angle θ ₁ before top dead center to the position at the angle θ ₂ . The charging section of capacitor 20 is abbreviated in mechanical angles.
360° (constant), as the engine speed increases, the terminal voltage V _c of the capacitor 30 decreases. Therefore, the position θ _x where the terminal voltage V _c of the capacitor 20 exceeds the reference voltage V _r moves toward the top dead center TDC as the rotation speed increases, as shown by the broken lines in FIG. 2 D and F. To go. In this example, when the engine speed reaches the set value N ₂ , θ _x becomes θ
₂ , and when the rotation speed exceeds N ₂ , θ _x further moves toward the top dead center side and becomes equal to θ ₃ at the set value N ₃ . Therefore, when the rotational speed exceeds N ₂ , a control signal is given at the position θ _x where the terminal voltage V _c of the capacitor 20 reaches the reference voltage V _r , and the engine ignition position increases as θ _x moves. It moves to the dead center side. Next, the rotation speed is the set value N ₃
, and when θ _x matches θ ₃ , the control signal is now given by the positive direction signal of the signal coil 25 whose peak value has become sufficiently large, so that the rotation speed exceeds the set value N ₃ In this case, the ignition position is fixed at an angle θ ₃ before top dead center.

As described above, the ignition is advanced in steps at the set rotation speed N ₁ , and the ignition position is advanced from the position of the angle θ ₂ before top dead center to the position of the angle θ ₃ in the range from the set rotation speed N ₂ to N ₃ . A characteristic of retarding the angle can be obtained. Here, the retard width θ _p corresponds to the width of the previous half cycle of the signal coil 25. The retard operation starts at the rotation speed N 2 at which the angle θ _x at which the terminal voltage of the capacitor 20 charged with a constant current reaches the reference voltage corresponds to a constant angle θ ₂ , and at the rotation speed _N at which the angle θ x coincides with the constant angle θ ₃ . ₃ , it is possible to clarify the rotational speed at which the retardation operation starts and the rotational speed at which it ends. In addition, without using a speed detection circuit that is directly affected by the generator's output, the terminal voltage of the capacitor that is charged at a constant current is compared with the reference voltage to perform control according to the rotation speed. Stable operation can be performed without being affected by fluctuations.

In the above embodiment, a control power source 9 that utilizes the negative output of the exciter coil 1 is used, but the configuration of this control power source is arbitrary, and a battery may also be used as the control power source.

As described above, according to the present invention, stable operation can be performed without being affected by output fluctuations of the generator, and the rotation speed at which the retardation operation starts and the retardation operation can be completed. This has the advantage that the rotation speed can be clearly determined.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing one embodiment of the present invention, Figure 2 is a connection diagram showing an embodiment of the present invention.
Figures A to F are diagrams showing signal waveforms at various parts in Figure 1, and Figure 3 is a diagram showing an example of lead angle and retard angle characteristics obtained by the present invention. 1...Exciter coil, 2...Diode,
3... Capacitor, 4... Ignition coil, 5... Thyristor (semiconductor switch for primary current control), 8
...Control circuit, 9...Control power supply, 17...
FET, 20...Ignition position control capacitor, 2
2... Zener diode, 23... Comparator, 2
5...Signal coil, 31...Transistor (semiconductor switch for setting ignition position control width).

Claims (1)

[Claims] 1. An ignition coil, a primary current control semiconductor switch that controls the primary current of the ignition coil, and control for applying a control signal to the primary current control semiconductor switch at the ignition position of the internal combustion engine to perform an ignition operation. an ignition device for an internal combustion engine, comprising: a control power source; a signal coil that generates a signal of one cycle per revolution of the internal combustion engine; and a control signal from the control power source to the semiconductor switch for controlling the primary current. and a circuit for supplying a control signal from the control power source when conductive is provided to bypass the primary current control semiconductor switch from the primary current control semiconductor switch, which generates a signal for the previous half cycle of the signal coil. a semiconductor switch for setting the ignition position control width that is controlled to be cut off only when the ignition position is controlled; a capacitor for controlling the ignition position; a charging circuit that charges the capacitor with a constant current; and a half-cycle signal generated after the signal coil. a reset circuit that discharges the capacitor at the rising position of the voltage, and a control signal given from the control power source side for a period when the terminal voltage of the capacitor is compared with a reference voltage and the terminal voltage of the capacitor is equal to or higher than the reference voltage. a comparator that allows the signal to be supplied to the semiconductor switch for controlling the primary current, and the signal coil applies a control signal to the semiconductor switch for controlling the primary current with the half-cycle signal generated after the signal. An ignition device for an internal combustion engine, characterized in that the ignition device is coupled to a control terminal of the primary current control semiconductor switch.