JPS6231671Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine that uses a transistor switch and is shaped like a current beam.

An ignition device for an internal combustion engine with a current-shaped cross section cuts off the current flowing through the coil at the ignition position, thereby further boosting the high voltage induced in the coil to obtain a high voltage for ignition. In non-contact current type ignition devices, transistor switches are often used as switches to control the current in the coil. Figure 1 shows a conventional ignition system for internal combustion engines using a transistor switch.
In the figure, 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, and 2 is a spark plug attached to a cylinder of an engine (not shown) and connected to both ends of the secondary coil 1b. The ignition coil 1 is disposed within a magnet 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 this example, the primary coil 1a also serves as the ignition power supply coil. 3 is a primary current control circuit that controls the primary current of the ignition coil, and this control circuit controls the main current that conducts when a base current is applied at the output of one half cycle of the ignition power supply coil (primary coil 1a). It consists of a control transistor switch circuit 4 and a shear cutoff control circuit 5 that controls the main current control transistor switch circuit to be cut off at the ignition position of the engine.

To explain in more detail, the main current control transistor switch circuit 4 has an emitter that is grounded.
An NPN transistor switch 401 is provided, and the collector of this transistor 401 is connected to the cathode of a diode 402 whose anode is connected to the non-grounded terminal of the primary coil 1a. Also, the base of the transistor 401 is connected to 1 through the resistor 403.
A diode 404 is connected to the non-grounded terminal of the secondary coil 1a, and is connected in parallel between the base and emitter of the transistor 401 with the anode on the emitter side.

The shearing control circuit 5 includes a transistor 501 serving as a shearing control semiconductor switch that bypasses the base current of the transistor 401 from the transistor when it is conductive, and the collector and emitter of the transistor 501 are connected to the transistor 401, respectively.
It is connected to the base and emitter of 01. The base of the transistor 501 is connected to one end of the resistor 502, and the other end of the resistor 502 and the transistor 50 are connected to each other.
A capacitor 503 for determining the ignition position is connected between the emitter 1 (ground) and the emitter 503 (ground). resistance 50
The cathode of a diode 504 is connected to the connection point between the capacitor 503 and the diode 50.
The anode of No. 4 is connected to the collector of a transistor 505 whose emitter is grounded. The transistor 505 constitutes a conduction signal bypass transistor switch that bypasses the conduction signal to the semiconductor switch for shear cut-off control (transistor 501) when it is conductive. It is connected to the non-grounded side terminal of the coil 1a. One end of a capacitor 508 is also connected to the non-grounded terminal of the primary coil 1a through a resistor 507, and a diode 50 whose anode is grounded is connected between the other end of the capacitor 508 and the ground.
9 are connected in parallel. Transistor 501~
Each component of the diode 509 constitutes the shear cutoff control circuit 5.

The conventional magnet generator in which the ignition coil 1 is arranged has four permanent magnets 8a to 8d fixed to the inner periphery of a cup-shaped iron flywheel 7, as shown in FIG. A four-pole flywheel magnet rotor 9 is provided, and this magnet rotor is attached to the rotating shaft of an engine (not shown). Also, on the stator side, there are approximately I
A letter-shaped iron core 10 is provided, and an ignition coil 1 is wound around this iron core 10. An iron core 11 having the same shape as the iron core 10 is also provided on the stator side, and a generating coil 12 used for charging a battery, driving a lamp load, etc. is wound around this iron core.

When the engine rotates in the above conventional ignition system for an internal combustion engine, the magnetic flux φ interlinking with the primary coil 1a changes as shown in FIG. 3A with respect to the rotation angle θ of the engine. A voltage Ve as shown in Figure B is induced. When a voltage is induced in the primary coil 1a for a half cycle in the direction of the dashed arrow shown in the figure (hereinafter, this half cycle will be referred to as a negative half cycle), the capacitor 508 is charged to the polarity shown in the figure through the diode 509 and the resistor 507, and becomes negative. When the half-cycle voltage exceeds the peak value, the capacitor 508 begins discharging along the path of the base and emitter of the transistor 505 -> the primary coil 1a -> the resistor 507 -> the capacitor 508. This discharge current continues to flow even after a positive half-cycle voltage in the direction of the solid arrow shown in the figure is induced in the primary coil 1a. Since the transistor 505 is in a conductive state while the capacitor 508 continues to discharge, the transistor 5
No base current is applied to the transistor 501, and the transistor 501 is in a low state. Therefore, when a positive half-cycle voltage is induced in the primary coil 1a, a base current flows to the transistor 401 through the resistor 403, this transistor becomes conductive, and a large current flows from the primary coil 1a through the diode 402 and the transistor 401. flows. The discharge time constant of the capacitor 508 is set so that the discharge current of the capacitor 508 becomes zero when the collector current of the transistor 401 reaches approximately the peak value when the engine speed is low.
When the discharge current of transistor 8 becomes zero, transistor 505 is turned off. When the transistor 505 is suddenly disconnected, the resistor 506 and diode 50 are removed from the primary coil 1a.
Since the base current flows to the transistor 501 through the resistor 501 and the resistor 501, the transistor 501 becomes conductive. When the transistor 501 becomes conductive, the base current is no longer supplied to the transistor 401, so that the transistor 401 is temporarily turned off, and the current flowing through the primary coil 1a is temporarily cut off. Since this current interruption occurs in an extremely short time, a high voltage is induced in the primary coil 1a, and this voltage is further increased to induce a high voltage for ignition in the secondary coil 1b. This voltage causes a spark discharge in the spark plug 2, and the engine is ignited.
The voltage induced in the primary coil 1a increases as the engine speed (rpm) increases, and as the engine speed increases to N ₀ , N ₁
For example, the induced voltage in the negative half cycle of the primary coil 1a when N ₂ (N ₀ <N ₁ <N ₂ ) is shown in FIG.
It becomes as shown with N ₀ , N ₁ and N ₂ attached. In this way, since the negative half cycle voltage of the primary coil 1a increases as the engine speed increases, the charging voltage of the capacitor 508 also increases as the engine speed increases. Therefore, as the engine speed increases, the position (ignition position) at which the discharge of the capacitor 508 ends becomes delayed, and the characteristic of the engine ignition position θ _i with respect to the engine speed N becomes the fourth
The result will be as shown in the figure. In other words, the ignition position tends to be gradually delayed in the high-speed range, and finally reaches a certain rotational speed Ns.
It will cause a misfire.

As mentioned above, the ignition system shown in FIG. 1 delays the ignition position when the engine is running at high speed, so it cannot be applied when the ignition position needs to be advanced at high speed. Furthermore, in the above ignition device, the ignition operation is performed every time a positive half-cycle voltage is induced in the ignition power supply coil, so if the magnet generator is configured with four poles as shown in Figure 2, The ignition is performed twice per revolution, and the ignition occurs at a position other than the ignition position of the engine, which has the disadvantage of adversely affecting the engine.

The purpose of this invention is to create an internal combustion engine that can perform one ignition operation per rotation even when using a four-pole magnet generator, and can advance the ignition position in the medium and high speed range. The purpose of this invention is to provide an ignition device for

The present invention includes an ignition power supply coil provided in a magnet generator having a four-pole magnet rotor, and a base current that is connected in parallel to the ignition power supply coil and is generated by the output of one half cycle of the ignition power supply coil. a main current control transistor switch circuit that conducts when the ignition power supply coil is supplied with a conduction signal and conducts when the output of the one half cycle of the ignition power supply coil is applied; a semiconductor switch for shunting control that bypasses current from the main current control transistor switch circuit; a capacitor that is charged by the output of the other half cycle of the ignition power supply coil; and a discharge current of the capacitor as a base current. and a conduction signal bypass transistor switch provided to bypass the conduction signal to the semiconductor switch for heat cutoff control from the semiconductor switch when the conduction is conducted, the main current control transistor switch circuit In an ignition system for an internal combustion engine that obtains a high voltage for ignition by boosting a high voltage induced in the ignition power supply coil due to a break in the current, the voltage across the main current control transistor switch circuit reaches a set value. a capacitor discharging semiconductor switch circuit that sometimes conducts to discharge the capacitor;
The present invention is characterized in that two adjacent magnetic poles among the four magnetic poles of the magnet rotor are made of permanent magnets, and the other two magnetic poles are made of unmagnetized magnetic material.

Hereinafter, the present invention will be explained in detail together with its embodiments with reference to FIGS. 5 to 8.

FIG. 5 shows an embodiment of the present invention, and parts equivalent to those in FIG. 1 are given the same reference numerals. The difference in FIG. 5 from the example in FIG. 1 is that a semiconductor switch circuit 6 for discharging a capacitor is turned on to discharge a capacitor 508 when the voltage across the main current control transistor switch 4 reaches a set value. This is the point I made. This switch circuit 6 includes a transistor 601 and a diode 60.
2, a resistor 603, and a variable resistor 604,
The transistor 601 has its collector connected to the connection point between the capacitor 508 and the diode 509, and its emitter connected to ground. Further, the anode of the diode 602 is connected to the primary coil 1a.
This diode 60 is connected to the non-grounded terminal of
A series circuit of a resistor 603 and a variable resistor 604 is connected between the cathode of No. 2 and ground. The base of the transistor 601 is connected to the connection point between the resistor 603 and the variable resistor 604. The series circuit of the diode 602, the resistor 603, and the variable resistor 604 is connected to the voltage across the series circuit of the diode 402 and the transistor 401 of the main current control transistor switch 4 (transistor switch 4
When the engine speed reaches the set value and the voltage across the transistor switch 4 reaches the set value, the transistor 60
A predetermined base current flows through the transistor 601 so that the transistor 601 becomes conductive.

In addition, in the present invention, as shown in Figure 6,
Half of the magnetic poles of the four-pole magnet rotor 9 of the magnet generator in which the ignition power supply coil is arranged are constituted by simulated magnets. That is, among the magnetic poles of the magnet rotor 9,
The two adjacent magnetic poles are permanent magnets 8a and 8b, and these magnets are magnetized in the radial direction so that magnetic poles of different polarities appear on the inner circumferential side. The other two adjacent magnetic poles of the magnet rotor 9 are composed of simulated magnets 8'c and 8'd made of unmagnetized ferromagnetic material (usually iron). The magnets 8a, 8b and the simulated magnets 8'c, 8'd are arranged at equal angular intervals of 90° on the inner circumference of the flywheel 7, and are located on the bottom wall of the flywheel 7 located in front of the page in FIG. Boss part 7 provided in the center of
A is fitted onto the rotating shaft of the engine, so that the magnet rotor 9 is attached to the engine. The stator side is constructed in the same manner as the example shown in FIG. The iron cores 10 and 11 are fixed to a stator base plate provided on an engine case, cover, etc. with screws or the like.

When the magnet generator is configured as shown in FIG. 6, the magnetic flux φ interlinking with the primary coil 1a of the ignition coil 1 is equal to the rotation angle of the engine (the rotation direction is the direction of the arrow shown in FIG. 6) θ 7A, and as shown in FIG. 6, the magnetic pole portions 10a of the iron core 10,
When magnets 8a and 8b face 10a, magnetic flux φ
becomes maximum. Further, while the simulated magnets 8'c, 8'd face the magnetic pole parts 10a, 10a, the magnetic flux interlinking with the primary coil 1a becomes zero. Furthermore, the magnetic pole portion 10a,
When a magnet faces one side of the coil 10a and a simulated magnet faces the other side, the peak value of the magnetic flux interlinking with the primary coil 1a is approximately 1/2 of the maximum value of the magnetic flux φ. Due to this magnetic flux change, the primary coil 1a
As shown in FIG. 7B, a negative voltage V ₁ with a relatively small peak value is generated at an angle θ ₀ , and then a positive voltage V ₁ with a large peak value is generated at an angle θ ₃ . The primary coil 1a also outputs a negative voltage V ₂ with a large peak value at an angle θ ₅ , and outputs a positive voltage V ₂ with a relatively small peak value at an angle θ ₇ .

Now, when a voltage _V 1 in the negative direction (in the direction of the dashed arrow in FIG. 5) is generated in the primary coil 1a at an angle θ ₀ ,
Capacitor 508 is charged to the polarity shown through diode 509 and resistor 507. The waveform of the terminal voltage of this capacitor 508 is as shown in FIG. 7E. When the voltage V ₁ passes the peak value at an angle θ ₂ , the capacitor 508 is connected to the transistor 50
5 base emitter, primary coil 1a and resistor 50
7 and begins to discharge with a substantially constant time constant. This discharge provides a base current to the transistor 505, which makes the transistor 505 conductive, thereby blocking the supply of base current to the transistor 501 and keeping the transistor 501 in a weak state. This state continues even after the positive direction voltage V ₁ is induced in the primary coil 1a at the angle θ ₃ . Therefore, when a voltage V ₁ is induced at an angle θ ₃ , a base current flows through the transistor 401, making the transistor 401 conductive, and a large current flows through the primary coil 1a. In a region where the engine speed N is below the set value N ₀ , the discharge of the capacitor 508 charged with the voltage V ₁ ends at a position θ _{i 0} near the angle θ ₄ where the collector current of the transistor 401 reaches its peak value. is set to . Therefore, in this region, the transistor 50 at the angle θ _i0
5 is then turned off, and transistor 501 is turned on. As a result, the transistor 401 is turned off, the current flowing through the primary coil 1a is cut off, and an ignition operation is performed. The charging voltage of the capacitor 508 increases as the rotational speed N of the engine increases, so when the rotational speed exceeds _N0 , the discharge end position of the capacitor 508 is delayed. Therefore, in the low speed region of the engine, the ignition position θi is slightly delayed as the engine speed increases, as shown in FIG. Engine speed is set value
When N ₁ (>N ₀ ) is reached, the collector current of the transistor 401 increases as the output of the primary coil 1a increases, resulting in a voltage drop across the diode 402 and a voltage drop between the collector and emitter of the transistor 401. becomes high, and a sufficient base current flows through the transistor 601 at an angle θ _i1 before the discharge of the capacitor 508 ends. As a result, the transistor 601 becomes conductive, and the capacitor 50
By forcibly discharging the charge of 8, the transistor 50
5. Therefore, when the rotational speed reaches _N1 , the ignition operation is performed at the position where the transistor 601 becomes conductive. diode 402
Since the forward voltage of the transistor 401 and the collector-emitter voltage of the transistor 401 are almost determined by the collector current value of the transistor 401, the current value at which the transistor 401 is turned off is almost constant. Further, the point at which the sum of the forward voltage of the diode 402 and the collector-emitter voltage of the transistor 401 reaches a level at which a predetermined base current flows through the transistor 601 is the point at which the output of the primary coil 1a increases as the engine speed increases. The ignition position θi advances as shown in FIG. 8 in the medium and high speed region where the rotational speed exceeds _N1 . In Fig. 8, TDC indicates the top dead center of the engine. In this manner, according to the present invention, a characteristic is obtained in which the ignition position θi is advanced as the rotational speed N increases in the medium to high speed rotation region of the engine.

Further, according to the device of the present invention, the ignition operation can be performed once per revolution of the rotor 9 for the following reasons. That is, after the ignition operation is performed at a predetermined ignition position of the engine, when a negative direction voltage V ₂ is generated in the primary coil 1a at an angle θ ₅ , the capacitor 508 is charged again, but the wave of this voltage V ₂ Since the high value V ₂ m is sufficiently larger than the peak value V ₁ m of the voltage V ₁ that occurs at the angle θ ₀ , the discharge of the capacitor 508 charged with this voltage V ₂ occurs at the angle θ ₇ ~
It continues even in the section where the transistor 401 at θ ₉ is conductive. Therefore, the transistor 50
5 is θ ₇ to _{θ 9} at which the transistor 401 is conductive.
The entire section of the transistor 401 is maintained in a conductive state, and the transistor 401
This prevents the ignition operation from occurring in this section by preventing the ignition from occurring. Also θ ₇ ~ _{θ 9}
The positive direction voltage generated in the primary coil 1a in the section of
Since V ₂ has a small peak value, the collector current flowing through the transistor 401 in this section has a small value. Therefore, the sum of the forward voltage drop of the diode 402 and the collector-emitter voltage of the transistor 401 is the voltage across the transistor 601. does not reach the level that triggers. Therefore, even in the middle and high speed range of the engine, ignition operation is not performed in the interval θ ₇ to _{θ 9} , and ignition operation is always performed once per revolution. In addition, in Fig. 7C, the rotation speed is N ₀ ,
In the case of N ₁ and N ₂ (N ₀ <N ₁ <N ₂ ), the primary coil 1a
FIG. 7D shows the waveform of the collector voltage of the transistor 505. Also, Fig. 7F shows the ignition coil 2.
It shows the waveform of the high voltage for ignition induced in the next coil.

In the above embodiment, the primary coil 1 of the ignition coil
Although "a" also serves as the ignition power supply coil, the present invention can also be applied to cases where the ignition power supply coil is provided inside the magnet generator and the ignition coil is provided outside the generator. In this case, the ignition power supply coil is connected in parallel to both ends of the series circuit of diode 402 and transistor 401 as shown in FIG.

In the embodiment described above, the transistor switch 4 consists of a single transistor, but it can also be replaced by a Darlington-connected composite transistor.

Further, although the transistor 501 is used as the semiconductor switch for controlling the heat cutoff in the above embodiment, it can be replaced with a thyristor. Similarly, a thyristor can be used as the switching element of the capacitor discharge semiconductor switch circuit 6.

As described above, according to the present invention, there is provided a capacitor discharge semiconductor switch circuit which conducts when the voltage across the main current control transistor switch circuit reaches a set value and discharges the ignition position determining capacitor. Since the ignition position is determined by conduction of this switch circuit in the medium to high speed range of the engine, there is an advantage that the ignition position can be advanced in the medium to high speed range. In addition, two of the four magnetic poles of the rotor of a four-pole magnet generator are formed of unmagnetized magnetic material, so that the capacitor charging voltage wave generated in the ignition power supply coil after the ignition operation is generated. By making the high value larger than the peak value of the capacitor charging voltage generated in the ignition power supply coil before the ignition position, ignition is prevented from occurring at positions other than the ignition position, thereby preventing unnecessary fire from flying into the engine. can be prevented.

[Brief description of the drawings]

Fig. 1 is a connection diagram showing a conventional example, Fig. 2 is a schematic configuration diagram of a magnet generator used in the device shown in Fig. 1, and Fig. 3 A and B are interlinkages of the ignition power supply coil of the generator shown in Fig. 2. Figure 4 is a diagram showing the magnetic flux and output voltage waveform; Figure 4 is a diagram showing the ignition characteristics obtained by the device in Figure 1;
The figure is a connection diagram showing one embodiment of the present invention, FIG. 6 is a schematic configuration diagram of a generator used in the embodiment of FIG. 5, and FIG.
Figures A to F are signal waveform diagrams of various parts in Figure 5, and Figure 8 is a diagram showing the advance angle characteristics obtained by the embodiment of Figure 5. 1...Ignition coil, 2...Spark plug, 3...
Current control circuit, 4... Main current control transistor switch circuit, 5... Shrinkage control circuit, 501...
...Transistor (semiconductor switch for cutting-off control), 505...Transistor, 508...Capacitor for determining ignition position, 601...Transistor, 602...Diode, 603...Resistor, 6
04...Variable resistor.

Claims (1)

[Scope of utility model registration request] An ignition power supply coil provided in a magnet generator having a 4-pole magnet rotor is connected in parallel to the ignition power supply coil, and a base current is applied by the output of one half cycle of the ignition power supply coil to conduction. A main current control transistor switch circuit is connected to the main current control transistor switch circuit, and when a conduction signal is applied to the output of the one half cycle of the ignition power supply coil and conduction occurs, the base current to the main current control transistor switch circuit is transferred to the main current control transistor switch circuit. a semiconductor switch for shearing control which is bypassed from a current control transistor switch circuit; and an ignition position determining capacitor that is charged by the output of the other half cycle of the ignition power supply coil;
and a conduction signal bypass transistor switch provided to conduct the discharge current of the capacitor as a base current and bypass the conduction signal to the semiconductor switch for damping control when conduction occurs. , an ignition device for an internal combustion engine that obtains a high voltage for ignition by boosting the high voltage induced in the ignition power supply coil due to the disconnection of the main current control transistor switch circuit; A capacitor discharging semiconductor switch circuit is provided, which conducts when the voltage at both ends reaches a set value to discharge the capacitor, and two adjacent magnetic poles among the four magnetic poles of the magnet rotor are connected to the permanent magnet. An ignition device for an internal combustion engine, wherein the other two magnetic poles are made of a non-magnetized magnetic material.