JPH0343422Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a device for stopping an internal combustion engine.

Prior Art In equipment that emphasizes ease of operation, such as agricultural machinery and small engine generators, a magnet generator is constantly connected to the ignition circuit of the internal combustion engine without using a key switch, and a rope start or kick start is used. It is ready to start immediately.
When the power source is constantly connected to the ignition circuit in this way, it is necessary to take special measures to stop the engine. Figure 1 shows an example in which the stop device proposed earlier by the present applicant (Utility Model Application No. 126187/1987) is applied to an engine using a capacitor discharge type ignition system. grounded 1
The ignition coil 2 has 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 in parallel to both ends of the secondary coil. Reference numeral 3 denotes an ignition energy storage capacitor whose one end is connected to the non-grounded terminal of the primary coil 1a, and a capacitor discharging control capacitor whose cathode faces the grounding side is connected to both ends of the series circuit between the capacitor and the primary coil. Thyristors 4 are connected in parallel.
The cathode of a diode 5 is connected to the connection point between the thyristor 4 and the capacitor 3, and the other end of an exciter coil 5 serving as an ignition power supply coil whose one end is grounded is connected to the anode of the diode 5. The above-mentioned parts constitute a capacitor discharge type ignition device.

In this ignition system, the exciter coil 6 is placed in a magnet generator (not shown) driven by the engine, and generates an alternating current in synchronization with the rotation of the engine. When the exciter coil 6 generates a voltage in the direction of the arrow shown in the figure, the capacitor 3 is charged through the diode 5 to the polarity shown. Next, when an ignition signal is applied to the thyristor 4 from a signal coil (not shown), the thyristor becomes conductive, and the charge in the capacitor 3 is discharged through the thyristor 4 to the primary coil 1a. This causes a large magnetic flux change in the iron core of the ignition coil, and a high voltage is generated in the secondary coil.
Therefore, a spark is produced in the spark plug 2, and the engine is ignited.

In order to stop the engine, an engine stopping thyristor 7 is connected in parallel to the exciter coil 6, and one end of a resistor 8 serving as current limiting means is connected to the gate of the thyristor 7. An engine stop capacitor 9 is connected between the other end of the resistor 8 and ground, and a cathode of a diode 10 is connected to the connection point between the capacitor 9 and the resistor 8. The anode of the diode 10 is connected to one end of a self-resetting manual stop switch 11, and the other end of the switch 11 is connected to the non-ground terminal of the exciter coil 6. The diode 10 constitutes a circuit that gives an ignition signal to the thyristor 7 when the manual switch is closed, and this circuit and the thyristor 7
An internal combustion engine stop device 12 is composed of the resistor 8 and the capacitor 9.

When the switch 11 is closed in the above-described stop device, when a voltage of the polarity shown is generated in the exciter coil 6, the capacitor 9 is charged to the polarity shown through the diode 10. capacitor 9
When charging is completed, thyristor 7 is
Since the ignition signal is applied to the thyristor 7 and the thyristor 7 becomes conductive, the exciter coil 6 is short-circuited through the thyristor 7. Therefore, charging of the capacitor 3 is blocked and ignition operation is blocked, causing the engine to misfire and its rotational speed to decrease. When the thyristor 7 becomes conductive, the voltage drop between the gate and cathode of the thyristor charges the capacitor 9 through the resistor 8 to the polarity shown. Capacitor 9 starts discharging through resistor 8 when the voltage between the gate and cathode of thyristor 7 exceeds its peak. The discharge time constant of this capacitor is set so that after the exciter coil 6 generates an output for a half cycle in the direction opposite to the illustrated arrow, the discharge continues until the output for the next half cycle rises. Therefore, when an output in the direction of the arrow shown in the figure is generated in the exciter coil, an ignition signal is applied to the thyristor 7 and the thyristor becomes conductive. The conduction of the thyristor 7 charges the capacitor 9 again, and the above-described operation is repeated. Therefore, while the engine is rotating and a voltage is induced in the exciter coil, the exciter coil undergoes a half cycle in the direction of the arrow shown in the figure (a half cycle that contributes to the ignition operation).
The thyristor 7 repeatedly conducts and continues to short-circuit the exciter coil, preventing the ignition operation and stopping the engine.

According to the above-mentioned engine stop device, since a self-resetting switch can be used as the switch 11, the stop device does not operate when restarting the engine, and there is no problem in starting the engine. . However, in the above device, it is necessary to sustain the discharge of the engine stop capacitor 9 for a half cycle in the direction opposite to the direction of the arrow shown in the figure of the exciter coil, so it is necessary to increase the discharge time constant of the capacitor. Therefore, it is necessary to increase the resistance value of the resistor 8. Therefore, it is not possible to increase the charging voltage when charging the capacitor 9 due to the voltage between the gate and cathode of the thyristor 7, and in order to ensure the discharge duration of the capacitor 9, it is necessary to increase the capacitance of the capacitor. It was hot.

As shown in FIG. 2, a switch 11 is connected in parallel to both ends of the thyristor 7 in the circuit shown in FIG. 1 as shown in FIG.
The diode 1 is connected to both ends of the exciter coil through the
A stopping device in which a zero cathode and an anode are connected has been proposed (Utility Model Application No. 55-15316). In this device, when the switch 11 is closed, the resistor 13 - switch 11 - diode 10 is connected to the exciter coil 6.
- Capacitor 9 is charged in the path of capacitor 9 - exciter coil 6, and when switch 11 is opened, capacitor 9 is discharged in the path of resistor 8 - gate cathode of thyristor 7 - resistor 14, and an ignition signal is sent to thyristor 7. Given. When the thyristor 7 becomes conductive, the voltage across the resistor 14 rapidly charges the capacitor 9 through the diode 10, and the voltage between the gate and cathode of the thyristor 7 additionally charges the capacitor 9 through the resistor 8.
FIG. 4 shows the change in the terminal voltage V9' of the capacitor 9 with respect to time t at this time.

In the figure, Vge is the voltage between the gate and cathode of the thyristor 7, and E2 is the peak value of the terminal voltage V9' of the capacitor 9. Therefore, in this device as well, it is possible to cause the engine to misfire by repeatedly energizing the thyristor 7 and to stop the engine. However, in this case, since the resistance value of the resistor 8 is large and the time constant determined by the resistance value and the capacitance of the capacitor 9 is large, the charging of the capacitor 9 performed through the resistor 8 by the gate-cathode voltage of the thyristor 7 is unable to do enough;
It was not possible to charge the capacitor 9 to the peak value of the voltage between the gate of the thyristor 7 and ground.

In this case, if the resistance value of the resistor 14 is increased, the charging voltage of the capacitor 9 can be increased, but if the resistance value of the resistor 14 is increased, the exciter coil 6 can be substantially short-circuited through the thyristor 7. It becomes impossible to stop the engine.

In this way, in the stop device shown in FIG. 2, the voltage Vge between the gate of the thyristor 7 and the ground cannot be fully utilized, so the charging voltage of the capacitor 9 cannot be increased, and the discharging time of the capacitor 9 cannot be increased. To ensure this, it was necessary to increase the capacitance of the capacitor considerably, and it was necessary to use a large and expensive capacitor.

Further, Utility Model Application Publication No. 58-4773 also shows a stopping device equipped with a diode similar to the diode 10 provided in the stopping device shown in FIG. As with the device shown in the figure, since it was connected between the cathode of the engine stop thyristor and the non-grounded terminal of the engine stop capacitor, the voltage between the gate and cathode of the engine stop thyristor could be fully utilized. First, it was inevitable that problems similar to those of the device shown in FIG. 2 would occur.

Purpose of the invention The purpose of the invention is to provide an internal combustion engine stopping device that can charge an engine stopping capacitor to a sufficiently high voltage, thereby reducing the capacitance of the capacitor. .

Structure of the Invention The present invention provides an engine stopping thyristor connected in parallel to a power coil of an ignition device for an internal combustion engine, and a gate cathode of the thyristor connected through a current limiting element. An engine stop capacitor that is charged by the voltage drop between the internal combustion engine and a self-resetting manual stop switch that is closed when the internal combustion engine is stopped.
an internal combustion engine stopping device comprising a circuit that gives an ignition signal to the thyristor when the manual switch is closed, an anode connected to the gate of the thyristor and a cathode connected to a connection point between the capacitor and the current limiting element. A diode is connected in parallel to the current limiting element.

With the above configuration, the engine stop capacitor is instantly charged via the diode by the voltage between the gate and cathode of the thyristor when the engine stop thyristor becomes conductive, so that the capacitor is always almost connected to the gate cathode of the thyristor. is charged to the voltage between the two. Therefore, a capacitor with a small capacity can be used as the engine stop capacitor, and costs can be reduced.

In the present invention, the engine stop capacitor only needs to be connected between the gate and cathode of the engine stop thyristor via a current limiting element, and a resistor is connected to the cathode side of the engine stop thyristor in series with the thyristor. Does not prevent insertion. In this way, by inserting a resistor in series with the cathode side of the engine stop thyristor, the engine stop capacitor can be charged using both the voltage between the gate cathode of the thyristor and the voltage across the resistor. The charging voltage of the capacitor can be made higher. However, in order not to impair the original function of the engine stop device, the resistance value of the resistor connected in series with the thyristor must be sufficiently small, so even in this case, the dominant charging voltage of the capacitor is This is the voltage between the gate and cathode of the thyristor for stopping the engine, and the effect of effectively using the voltage between the gate and cathode of the thyristor for stopping the engine as the charging voltage for the capacitor for stopping the engine as in the present invention is remarkable.

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

FIG. 3 shows an embodiment in which the present invention is applied to the stop device of the type shown in FIG. 1. In FIG. 3, parts equivalent to those in FIG. There is. In this embodiment, a resistor 14 having a sufficiently small resistance value is inserted between the cathode of the engine stop thyristor 7 and the ground, and a resistor 15 is connected in parallel to both ends of the series circuit of the diode 10 and the engine stop capacitor 9. There is. In the present invention, a diode 16 whose anode is directed toward the gate of the thyristor 7 is connected in parallel to both ends of the resistor 8 as a current limiting element. The rest of the structure is similar to that of the apparatus shown in FIG.

In the embodiment described above, the ignition operation is similar to the device of FIG. When the switch 11 is closed to stop the engine, when a voltage is generated in the exciter coil 6 in the direction of the arrow shown in the drawing, the capacitor is charged through the exciter coil 6-diode 10-capacitor 9-exciter coil 6 path.
When the output voltage of the exciter coil in the direction of the arrow passes the peak, the charge in the capacitor 9 is discharged between the resistor 8 and the gate cathode of the thyristor 7 and through the resistor 14, so that an ignition signal is given to the thyristor 7. Thyristor 7 is therefore conductive and exciter coil 6 is essentially short-circuited through thyristor 7 and resistor 14. This prevents the capacitor 3 from charging, causing the engine to misfire. Thyristor 7
When conductive, capacitor 9 is charged to the polarity shown through diode 16 by the sum of the voltage drop between its gate and cathode and the voltage drop across resistor 14. Since the resistance value of the resistor 14 is small and the charging time constant of the capacitor 9 is small, the capacitor 9 is approximately equal to the gate-cathode voltage of the thyristor 7.
Charged to the peak value Ep of Vge. The change in the terminal voltage V9 of the capacitor 9 with respect to time in the device shown in FIG. 3 is shown in FIG. I understand. Therefore, even if the capacitance of the capacitor 9 is made small, the discharge duration of the capacitor can be ensured. In FIG. 4, Et indicates the trigger level of the thyristor 7, and the discharge time constant of the capacitor 9 is set so as not to reduce the terminal voltage of the capacitor below this trigger level Et.

Although a capacitor discharge type ignition device is used in the above embodiment, the present invention can be similarly applied to cases where other types of ignition devices are used. For example, as shown in FIG. 5, a primary coil (also serving as an exciter coil) 1a of an ignition coil is placed in a magnet generator driven by an engine.
A well-known method in which a switch 20 such as a transistor is connected in parallel to the primary coil 1a, and the ignition operation is performed by changing the switch 20 from a conductive state to a cut-off state during a half cycle of the voltage induced in the primary coil 1a in the direction of the arrow shown in the figure. The present invention can also be applied when a current cutoff type ignition device is used.

Further, as shown in FIG. 6, a transistor 22 is connected to both ends of the exciter coil 6 via a diode 21.
The collector-emitter circuit is connected in parallel, a thyristor 23 is connected in series with the primary coil 1a, and the base of the transistor 22 and the anode of the thyristor 23 are coupled via a diode 24. The present invention can also be applied when an ignition device is used. In this ignition device, spark plugs 2 and 2' are connected between both ends of the secondary coil of the ignition coil and the ground, respectively, and these spark plugs are connected to two cylinders in which there is no problem even if sparks are generated at the same time, e.g. Each is attached to two cylinders such that one is in the ignition timing and the other is in the exhaust stroke. In the ignition system shown in FIG. 6, the output voltage of the exciter coil 6 in the direction of the arrow shown in the diagram causes the primary coil 1a and
A base current is applied to the transistor 22 through the transistor 4, making the transistor conductive. Next, when a firing signal is applied to the thyristor 23 from a signal coil (not shown), the thyristor becomes conductive and the transistor 22 is turned off. Therefore, from the exciter coil 6 to the diode 21 and the transistor 2
The current flowing through the exciter coil 6 is cut off, and a high voltage is induced in the exciter coil 6. This high voltage is further boosted by the ignition coil 1 and applied to the ignition plugs 2, 2', so that sparks are generated at both ignition plugs simultaneously.

In the above embodiment, the resistor 8 is used as the current limiting element, but a semiconductor element such as a diode with the cathode facing the gate of the thyristor 7 can also be used as the current limiting element.

Effects of the invention As described above, according to the invention, by connecting a diode in parallel to the current limiting element that couples the gate of the engine stop thyristor to the engine stop capacitor, the charging time constant of the capacitor can be reduced. Therefore, the engine stop capacitor can be charged by the gate to cathode voltage of the engine stop thyristor to almost the peak value of the gate to cathode voltage, and the gate to cathode voltage of the engine stop thyristor can be effectively used. can charge the capacitor to a sufficiently high voltage. Therefore, even if an inexpensive capacitor with a small capacity is used as the capacitor, the capacitor can be discharged for the required time, and the cost of the device can be reduced.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 are circuit diagrams showing different conventional examples, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 is a circuit diagram showing a change in terminal voltage of an engine stop capacitor in a conventional manner. 5 and 6 are circuit diagrams showing other different embodiments of the invention, respectively. 1...Ignition coil, 2...Spark plug, 3...
Ignition energy storage capacitor, 4... Thyristor, 6... Exciter coil (ignition power supply coil), 7... Engine stop thyristor, 8... Resistor (current limiting element), 9... Engine stop capacitor,
10... Diode, 11... Self-resetting manual stop switch, 12... Engine stop device, 1
6... Diode, 20... Switch for controlling the primary current of the ignition coil, 21, 23... Diode, 22... Transistor, 23... Thyristor.

Claims (1)

[Scope of utility model registration request] An engine stopping thyristor connected in parallel to a power supply coil of an ignition device for an internal combustion engine and a gate cathode of the thyristor are coupled through a current limiting element and charged by a voltage drop across the gate cathode of the thyristor. an internal combustion engine stop capacitor, a self-resetting manual stop switch that is closed when the internal combustion engine is stopped, and a circuit that provides an ignition signal to the thyristor when the manual switch is closed. An internal combustion engine stopping device characterized in that a diode having an anode connected to the gate of the thyristor and a cathode connected to a connection point between the capacitor and the current limiting element is connected in parallel to the current limiting element.