JPH0219593Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an ignition device for an internal combustion engine that uses a signal generator as an ignition signal source, and particularly relates to an ignition device for an internal combustion engine that can prevent reverse rotation of the engine.

Prior Art Since a two-stroke internal combustion engine can rotate in reverse, if an ignition device that can ignite even when the engine rotates in reverse is used, there is a problem that once the engine rotates in reverse, the engine will continue to rotate in reverse. There is. Generally, an ignition signal generator generates a positive polarity signal voltage and a negative polarity signal voltage in a signal coil in response to changes in interlinkage magnetic flux of the signal coil near the ignition position of an engine.
The ignition circuit is operated by a signal of one of the polarities to generate an engine ignition voltage. However, with this type of ignition signal generator, even when the engine is rotating in reverse, it generates signals of negative and positive polarity that are reversed in polarity with respect to the rotation angle position, so if the engine is rotating in reverse for some reason. In some cases, the ignition circuit may operate in the same way as when the engine is running in the normal direction, causing the engine to continue rotating in the reverse direction. Therefore, various ignition devices for internal combustion engines have been proposed in which the ignition operation is not performed when the engine rotates in reverse. One of the conventional ignition devices of this kind is to generate a signal of a second polarity (e.g., negative polarity) at a time delayed from a signal of the first polarity (e.g., positive polarity) when the engine rotates in the normal direction at the ignition position of the engine. However, there is an ignition signal generator that uses an ignition signal generator configured to generate a signal of the second polarity earlier than a signal of the first polarity when the engine is reversed. In this ignition device, the ignition circuit is operated by the signal of the first polarity to generate engine ignition voltage, and when the engine is reversed, the switching element is operated by the output of the time circuit operated by the signal of the second polarity. This prevents the signal of the first polarity from being applied to the ignition circuit.
No. 43940). However, this type of ignition system that has been proposed in the past only blocks the first polarity signal, so the signal generator may generate a noise signal due to vibrations from the engine or may be induced by other sources. When noise voltages are induced in the signal circuit, these noise signals are applied to the ignition circuit, causing the ignition circuit to malfunction, making it impossible to reliably prevent the engine from reversing.

Purpose of the invention An object of the present invention is to provide an ignition device for an internal combustion engine that can prevent reverse rotation of the engine with a simple configuration.

Structure of the invention The invention outputs a signal of negative polarity followed by a signal of positive polarity when the engine rotates in the forward direction in synchronization with the rotation of the engine, and outputs a signal of negative polarity following the signal of positive polarity when the engine rotates in reverse. An ignition signal control switch means comprising: an ignition signal generator; and a control terminal that receives the positive polarity signal of the ignition signal generator and becomes conductive to output an ignition signal when the positive voltage reaches a predetermined value; , and an ignition circuit that receives the ignition signal as input and generates a high voltage for ignition, and the ignition signal generator has a positive polarity signal voltage whose peak value is a negative polarity signal voltage during forward rotation. The capacitor is charged by the negative signal, and the charging voltage of the capacitor is used for controlling the ignition signal. A reverse bias circuit for reverse biasing the control terminal of the switch means and a discharging circuit for discharging the capacitor at a predetermined time constant are provided so that when the engine is reversed, the charging voltage of the capacitor is equal to the signal voltage of the positive signal. An ignition device for an internal combustion engine characterized in that the time constant of the discharge circuit is set so as not to become lower than a peak value. With this configuration, the control terminal of the ignition signal control switch means is reverse biased by the charging voltage of the capacitor charged by the negative signal output from the ignition signal generator, and the time constant of the capacitor discharge circuit is is set so that the charging voltage of the capacitor does not become lower than the peak value of the voltage of the positive signal output from the ignition signal generator when the engine rotates in reverse, so the ignition operation by the positive signal when the engine rotates in reverse. In addition to being able to prevent
This has the advantage of reliably preventing malfunctions caused by noise or the like.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Figure 1 shows a circuit of an embodiment of the present invention. In the figure, 1 is an ignition signal generator that generates an ignition signal in synchronization with the rotation of the engine, and 2 is an output from the ignition signal generator 1. An ignition circuit 3 generates a high voltage for engine ignition in accordance with a signal from the ignition signal generator 1, and an ignition signal control circuit 3 controls the signal from the ignition signal generator 1. The ignition signal generator 1 is provided with a signal coil 11 whose one end is grounded, and when the engine rotates in the normal direction, a negative polarity signal v 1 in the direction of the broken line arrow shown in the figure follows the negative polarity signal v ₁ in the direction of the broken line arrow shown in the figure when the engine rotates in the forward direction, and the solid line shown in the figure has a larger amplitude. Generates a signal v ₂ of positive polarity in the direction of the arrow, and when the engine is reversed, generates a signal v ₃ ′ of positive polarity in the direction of the solid arrow shown in the figure, followed by a signal v ₂ ′ of negative polarity in the direction of the dashed arrow with a larger amplitude. is configured to do so.
In this specification, a signal of polarity used for ignition operation is referred to as a signal of positive polarity, and a signal of polarity not used for ignition operation is referred to as a signal of negative polarity. FIG. 2 shows an example of an ignition signal generator that generates the above-mentioned signal in the signal coil 11. This signal generator consists of a magnet rotor 12 and a stator 1.
It consists of 3. In the magnet rotor 12, a permanent magnet 16 magnetized in the radial direction of the rotor body is fixed in a recess 15 of a rotor body 14 made of a magnetic material, and magnetic poles of the illustrated polarity are formed on the outer periphery. The center portion of the shaft 12 has a shaft mounting hole 17 into which a drive shaft such as an output shaft of an engine is fitted. Stator 13
is constructed by winding a signal coil 11 with one end grounded around a substantially U-shaped laminated iron core 18 having pole spacing such that it faces adjacent magnetic poles of different polarity of a magnet rotor 12 with an air gap in between. . In this signal generator, when the engine rotates in the forward direction and the magnet rotor 12 rotates in the forward clockwise direction, the signal coil 1
The magnetic flux φ interlinking with 1 changes as shown in FIG. 3a, and in response to this change in magnetic flux, a negative polarity voltage v ₁ ,
A positive polarity voltage v ₂ and a negative polarity voltage v ₃ are sequentially induced. The positive voltage v ₂ generated at a position where the change in magnetic flux φ is large has a larger amplitude or peak value than the negative voltages v ₁ and v ₂ generated at positions where the change in magnetic flux φ is smaller. When the engine rotates in the opposite direction and the magnet rotor 12 rotates counterclockwise, the polarity of the voltage induced in the signal coil 11 is opposite to that in the case of forward rotation for the same rotational angular position of the magnet rotor 12. , the output waveform is induced in the order of positive polarity voltage v ₃ ', negative polarity voltage v ₂ ' and positive polarity voltage v ₁ ' as shown by the broken line in FIG. 3b (time passes from right to left). In this case, the amplitude of the negative polarity voltage v ₂ ′ is equal to the positive polarity voltage
greater than the amplitudes of v ₃ ′ and v ₁ ′.

To explain the configuration of the ignition circuit 2, reference numeral 21 is an exciter coil that is installed in a magnet generator that rotates synchronously with the engine and generates an AC output, and 22 is an ignition coil that has a primary coil 22a and a secondary coil 22b. One end of the coil 22a is connected to the non-ground terminal of the exciter coil 21. 23 is a spark plug connected to the secondary coil 22b; 24
is connected to the exciter coil 21 via the diode 25.
Transistor 24 is a transistor connected in parallel to , and when turned on, short-circuits the output of exciter coil 21 in the direction of the arrow in the figure. A base circuit consisting of a series circuit of a diode 29 and a resistor 26 is connected between the other end of the primary coil 22a and the base of the transistor 24. A thyristor 27 is connected between the connection point of the anode of the diode 29 and the primary coil 22a of the ignition coil and the emitter of the transistor 24, and when the thyristor 27 becomes conductive, it bypasses the base current of the transistor 24. The transistor is turned off. 28 is a resistor connected between the gate and cathode of the thyristor 27. The above ignition means 2 is a known transistor type magneto ignition circuit, and the exciter coil 2
1, when a voltage in the direction of the arrow shown in the figure is induced, a base current is supplied to the transistor 24 through the primary coil 22a of the ignition coil 22, the diode 9, and the resistor 26, making the transistor conductive. flows. When an ignition signal is applied to the gate of the thyristor 27 when the instantaneous value of this short-circuit current reaches a substantially maximum value, the thyristor 27 becomes conductive and bypasses the base current of the transistor 24. Therefore, the transistor 24 is cut off and the short circuit current of the exciter coil 21 suddenly flows to the primary coil 22a of the ignition coil. Therefore, the core magnetic flux of the ignition coil 22 changes suddenly, and a high voltage is induced in the secondary coil 22b, causing the ignition plug 23 to generate an ignition spark.

To explain the configuration of the ignition signal control circuit 3, 31
is a PNP transistor as a switch means for controlling the ignition signal, the collector of the transistor 31 is connected to the gate of the thyristor 27 in the ignition circuit 2, and the anode of the emitter is connected to the non-grounded output terminal of the signal coil 11. A resistor 33 is connected to the cathode of the diode 32, and further connected between the base and emitter. 34 is a bias capacitor, one end of the capacitor 34 is connected to the anode of a diode 35 whose cathode is connected to the non-grounded terminal of the signal coil, and the other end is connected to the cathode of a diode 36 whose anode is grounded. ing. A resistor 37 is connected in parallel to both ends of the capacitor 24, and a resistor 37 is connected between one end of the capacitor 34 and the anode of the diode 35 and the anode of the diode 36.
8 are connected.

Next, the operation of the above embodiment will be explained. When the rotor 12 of the ignition signal generator shown in FIG. 2 rotates in the normal direction when the engine rotates in the normal direction, a signal voltage as shown by the solid line in FIG. 4a is induced in the signal coil 11 with respect to the rotation angle θ. This waveform is similar to that shown by the solid line in FIG. 3b. When a negative polarity voltage v ₁ is induced in the signal coil 11 at an angle θ ₁ , a current flows through the path of the signal coil 11 → diode 36 → capacitor 34 → diode 35 → signal coil 11, and the capacitor 3
4 to the polarity shown in FIG. The waveform of the terminal voltage v _c of the capacitor 34 is shown by the broken line in FIG. 4a. Then, signal coil 1 at angle θ ₂
When a positive polarity voltage v ₂ is induced in 1, this voltage v ₂ flows from signal coil 11 → diode 32 → transistor 3
A current is applied to the transistor 31 in the direction of supplying the base current i _b by flowing the current between the emitter and collector of the transistor 1 and through the paths from the resistor 33 to the capacitor 34 and from the resistor 37 to the resistor 38. However, capacitor 3
Since the terminal voltage v _c of No. 4 provides a reverse bias voltage to the above circuit, the base current i _b does not flow immediately. That is, in the positive rotation of the signal voltage output by the ignition signal generator 1, the amplitude of the positive polarity voltage v ₂ is larger than the amplitude of the negative polarity voltage v ₁ ;
When the positive polarity voltage v ₂ rises and the instantaneous value of the voltage v ₂ reaches the terminal voltage of the capacitor 34, that is, the value of the reverse bias voltage v _c at the angle θ _i , from this position there is a voltage between the emitter and the base of the transistor 31. As shown in FIG. 4b, the base voltage v _b is applied in the forward direction. Therefore, this transistor 31 receives a base current from the position of angle θ _i as shown in FIG. 4c.
i _b flows. As a result, the transistor 31 becomes conductive, and an ignition signal v _t is applied to the gate of the thyristor 27 of the ignition circuit 2 as an ignition signal as shown in FIG. 4d.
is applied, so the ignition circuit 2 operates and generates a high voltage for engine ignition. The charge in the capacitor 34 is then discharged through the resistor 37.
The value of the time constant determined by the capacitance value of the capacitor 34 and the resistance value of the resistor 37 is selected to be relatively large, so that the reverse bias voltage v _c is maintained until the next ignition position. Therefore, even if a noise voltage v _o having an amplitude lower than the reverse bias voltage v _c occurs in the output side circuit of the signal coil 11 as shown in FIG. There is no.

Next, when the rotor 12 of the ignition signal generator shown in FIG. 2 rotates in the reverse direction when the engine rotates in the reverse direction, the signal coil 11
, a signal voltage as shown by the solid line in FIG. 5 is induced with respect to the rotation angle θ. This waveform is similar to that shown by the dashed line in FIG. 3b. When a negative signal voltage v ₂ ' is induced in the signal coil 11 at an angle θ ₃ , this voltage v ₂ ' causes the diodes 36 and 35 to
Through this, capacitor 34 is charged to the polarity shown in FIG. 1, and the terminal voltage v _c ' of capacitor 34 becomes as shown by the broken line in FIG. The capacitor 34 is charged to a value approximately equal to the peak value of the signal voltage v ₂ '. Therefore, even if a positive signal voltage v ₁ ' is induced in the signal coil 11 at an angle θ ₂ , the capacitor 34
Since the reverse bias voltage v _c ' is larger than the signal voltage v ₁ ', no base current flows through the transistor 31, and the transistor 31 is not conductive. Since the charge in the capacitor 34 is discharged through the resistor 37, the reverse bias voltage v _c ' given by the terminal voltage of the capacitor 34 decreases over time, but the CR time constant is then changed to positive polarity at an angle θ ₄ . Since the value of the reverse bias voltage v _c ′ is set to be larger than the peak value of the signal voltage v ₃ ′ when the signal voltage v ₃ ′ is induced, the positive polarity signal voltage v ₃ ′ is induced, the transistor 31 does not conduct. Therefore, no ignition signal is applied to the thyristor 27 of the ignition circuit 2. Reverse bias voltage from positive polarity voltage v ₃ ′
The conditions for the value of v _c ′ to become large are approximately given as follows. In other words, it is assumed that a signal voltage is generated once in the signal coil 11 during one rotation of the engine, and the minimum rotation speed (idling rotation speed) of the engine is
N ₀ (rpm), positive polarity signal voltage v ₃ ′ and negative polarity signal voltage
If the ratio of the diagnostic width of v ₂ ' is α, the capacitance of the capacitor 34 is C, and the resistance value of the resistor 37 is R, the above condition becomes the following formula: RC>60/N ₀ lnα. In the present invention, the magnitude of the signal voltages v ₂ ′ and v ₃ ′ and the time constant due to the capacitor 34 and resistor 37 are
Since the value of RC is set to satisfy the above conditions, if the engine speed exceeds idling speed when the engine is rotating in reverse, no ignition signal is given to ignition circuit 2, and therefore the engine continues to rotate in reverse. do not. Furthermore, even if a noise voltage vo having an amplitude lower than the reverse bias voltage v _{c '} occurs in the output circuit of the signal coil 11 as shown in FIG. 5, the transistor 31 will not become conductive due to this noise. .

FIG. 6 shows a circuit showing another embodiment of the present invention, in which an NPN transistor 31' is used as a switch element for controlling the ignition signal.
The same members as those shown in FIG. 1 are given the same reference numerals. Further, since the circuit configuration of the ignition circuit 2 is the same as that in FIG. 1, only a part of the circuit is shown. The operation of the embodiment shown in FIG.
The positive polarity signal voltage v ₂ causes the transistor 31' to
The path that supplies the base current to is the signal coil 11→
Since the path is substantially the same except that the path is from resistor 38 to capacitor 34 and resistor 37 to base-emitter of transistor 31' to diode 32 to resistor 28 of ignition means 2 to signal coil 11, the explanation will be omitted.

In the above embodiment, the transistor 31 or 31' is used as the ignition signal control switch means, but the same effect can be obtained by using a control switch element such as a thyristor instead of the transistor 31 or 31'. . Also, instead of using a single magnet generator as shown in Figure 2 as an ignition signal generator, it is constructed integrally with a magnet generator for the ignition power source of the ignition circuit 2, and when the engine rotates in the forward direction, the negative polarity is turned on. Even if an ignition signal generator is used that generates a positive signal with a larger amplitude following the signal, and generates a negative signal with a larger amplitude after the positive signal when the engine is reversed. good. Further, in the above embodiment, a transistor type magneto ignition circuit is used as the ignition circuit 2, but the present invention can also be applied when a capacitor discharge type ignition circuit or a battery power source current cut-off type ignition circuit is used as the ignition means 2. Applicable.

Effects of the invention As described above, according to the invention, the control terminal of the ignition signal control switch means is reverse biased by the charging voltage of the capacitor charged by the negative polarity signal output from the ignition signal generator. The time constant of the capacitor discharge circuit is set so that when the engine rotates in reverse, the charging voltage of the capacitor does not become lower than the peak value of the voltage of the positive signal output from the ignition signal generator. This has the advantage that not only can ignition operations caused by positive polarity signals be prevented, but also malfunctions caused by noise or the like can be reliably prevented.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a schematic configuration diagram showing an example of the ignition signal generator used in the present invention, Figures 3a and 3b are flux linkage waveform diagrams and induced voltage waveform diagrams of the signal coil in the ignition signal generator of Figure 2, and Figure 4 is a diagram of the induced voltage waveform. The figure is a voltage and current waveform diagram of each part when the engine rotates forward in the embodiment shown in Figure 1, Figure 5 is a voltage waveform diagram of each part when the engine rotates reversely in the same embodiment, and Figure 6 is FIG. 3 is a circuit diagram showing another embodiment of the present invention. 1...Ignition signal generator, 11...Signal coil,
2... Ignition circuit, 21... Exciter coil for ignition power supply, 22... Ignition coil, 23... Spark plug, 24... Transistor, 25... Diode, 27... Thyristor, 26, 28... Resistor,
3... Ignition signal control circuit, 31... Transistor (switch element for ignition signal control), 34... Capacitor (for bias), 32, 35, 36... Diode, 33, 37, 38... Resistor.

Claims (1)

[Scope of utility model registration request] an ignition signal generator that outputs a signal of negative polarity followed by a signal of positive polarity when the engine rotates forward in synchronization with the rotation of the engine; and a signal of negative polarity following the signal of positive polarity when the engine reverses; ignition signal control switch means having a control terminal which receives the positive polarity signal of the ignition signal generator and which becomes conductive and outputs the ignition signal when the positive polarity voltage reaches a predetermined value; In an internal combustion engine ignition system comprising an ignition circuit that generates a high voltage for ignition, the ignition signal generator has a positive polarity signal voltage whose peak value is higher than a negative signal voltage during forward rotation, and a positive polarity during reverse rotation. A capacitor is charged by the negative polarity signal, and the charging voltage of the capacitor is connected to the control terminal of the ignition signal control switch means. A reverse bias circuit that reversely biases the capacitor and a discharge circuit that discharges the capacitor at a predetermined time constant are provided to prevent the charging voltage of the capacitor from becoming lower than the peak value of the signal voltage of the positive polarity signal when the engine is reversed. An ignition device for an internal combustion engine, characterized in that a time constant of the discharge circuit is set.