JPH0341093Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an internal combustion engine stop device that stops the engine when the level of lubricating oil in a two-stroke or four-stroke internal combustion engine falls below a permissible lower limit level. .

[Prior Art] When the level of lubricating oil in an internal combustion engine falls below a permissible lower limit level, if the engine continues to be operated, the engine may be damaged. Therefore, an internal combustion engine stop device has been proposed that protects the engine by detecting the oil level of the engine and causing the engine to misfire and stop when the oil level falls below the allowable lower limit level.

Figure 5 shows a conventional device of this type.
In the figure, 1 is an ignition device for an internal combustion engine, and 2 is an internal combustion engine stop device. The internal combustion engine ignition device shown in FIG. 5 comprises an ignition coil 3, which ignition coil, at least its primary coil 3a, is arranged in a magnet generator driven by the internal combustion engine. That is, in this example, the primary coil 3a also serves as an ignition power supply coil, and an alternating current voltage is induced in the primary coil 3a in synchronization with the rotation of the engine.

One end of the primary coil 3a and the secondary coil 3b of the ignition coil 3 is grounded, and a diode 4 with a cathode facing the ground side is connected to both ends of the primary coil 3a. A collector-emitter circuit of an NPN transistor 5 serving as a current control switch is connected in parallel to both ends of the primary coil 3a with its collector facing the ground side. Although not shown, a control circuit for the transistor 5 is provided, and this control circuit causes a base current to flow through the transistor 5 to make the transistor 5 conductive when a voltage in the direction of the arrow shown in the figure is induced in the primary coil 3a. transistor 5
The control circuit also turns off the transistor 5 at an ignition timing set during a period in which a voltage in the direction of the arrow shown in the figure is induced in the primary coil 3a. As a result, the current flowing from the primary coil (ignition power supply coil) through the collector-emitter of the transistor 5 is interrupted, and a voltage is induced in the primary coil 3a. This voltage is boosted by the ignition coil, and a high voltage for ignition is induced in the secondary coil 3b. Since this high voltage is applied to the spark plug 6 attached to the cylinder of the engine, a spark is generated in the spark plug and the engine is ignited.

The internal combustion engine stop device 2 includes an engine stop thyristor 7 connected in parallel to a primary coil (power supply coil) 3a, and a thyristor 7 to prevent the thyristor 7 from becoming conductive due to an excessive rate of voltage change. A series circuit of a resistor 8 and a capacitor 9 connected in parallel between the anode and cathode of the thyristor 7, and a resistor 10 and a capacitor 11 connected in parallel between the gate and cathode of the thyristor 7 to prevent the thyristor 7 from collapsing. An oil level detection switch 12 is connected between the anode gate of the thyristor 7.
is connected.

The oil level detection switch 12 closes when the level of lubricating oil in the internal combustion engine falls below an allowable lower limit level. When the oil level detection switch 12 closes, the primary coil 3a induces a voltage in the direction of the arrow in the figure (the half cycle in which the ignition operation is performed).
A trigger signal is supplied to the thyristor 7 through 2. This makes the thyristor 7 conductive and short-circuits the primary coil 3a. Thyristor 7 is the primary coil 3
While a is inducing a voltage in the direction of the arrow in the figure, it remains conductive and continues to short-circuit the primary coil 3a, so ignition is no longer performed and the engine misfires. As long as the oil level of the internal combustion engine remains below the allowable lower limit level and the switch 12 is closed, the above operation will be repeated and the ignition operation will continue to be blocked, so that the engine will eventually stop.

In the internal combustion engine stop device shown in FIG. 5, a trigger signal is supplied to the thyristor 7 through the oil level detection switch 12 with the output of one half cycle that contributes to the ignition operation of the power supply coil (primary coil 3a in the above example). Therefore, when the detection switch 12 is open, the primary induced voltage (about 400V) of the ignition device is always applied to the detection switch. Therefore, a high pressure-resistant oil level detection switch 12 is required, but there are many technical difficulties in obtaining a high-voltage oil level detection switch.
It is unavoidable that the cost will rise significantly.

Therefore, as shown in FIG. 6, a device has been proposed in which a half-cycle output that does not contribute to the ignition operation of the power supply coil is used to supply a trigger signal to the engine stop thyristor. In this device, a diode 13 is connected between the gate and cathode of the engine stop thyristor 7, one end of a capacitor 14 is connected to the gate of the thyristor, and the other end of the capacitor 14 is connected to the diode 15 and the oil level detection switch 12. through the power coil (1
It is connected to one end of the next coil 3a). Further, a resistor 16 is connected between the other end of the capacitor 14 and the cathode of the thyristor 7.

In the device shown in FIG. 6 above, when the oil level of the internal combustion engine falls below the permissible lower limit level and the oil level detection switch 12 is closed, the voltage in the direction opposite to the arrow shown in the primary coil 3a (ignition operation A half-cycle voltage (not contributing to the voltage) charges capacitor 14 through diodes 13 and 15 and detection switch 12 to the polarity shown.
The charge in the capacitor 14 is discharged between the gate and cathode of the thyristor 7 and through the resistor 16, so that the thyristor 7 supplies a trigger signal.

[Problems to be solved by the invention] As shown in Figure 6, if the engine stop thyristor is triggered using the half-cycle output voltage that does not contribute to the ignition operation of the power supply coil, the oil Since a high voltage induced on the primary side of the ignition device is not applied to the level detection switch 12, an inexpensive one with a low withstand voltage can be used as the oil level detection switch 12.

However, in an ignition system for an internal combustion engine, as shown in Fig. 5, the half-cycle output that does not contribute to the ignition operation of the power supply coil (primary coil 3a) is often short-circuited by a diode. In such cases, the configuration shown in FIG. 6 cannot be adopted.

Furthermore, in both the devices shown in FIGS. 5 and 6, the thyristor 7 is
Since it is necessary to connect a series circuit of a resistor 8 and a capacitor 9 in parallel to the thyristor 7 in order to protect the circuit from dt), there is also the problem that the number of circuit components increases and the cost increases.

The purpose of this invention is to make it possible to use a low-voltage oil level detection switch even when the half-cycle output that does not contribute to the ignition operation of the power supply coil is short-circuited, and to make it possible to use an engine stop thyristor that is An object of the present invention is to provide an internal combustion engine stopping device that can omit a series circuit of a resistor and a capacitor provided for protection from a voltage change rate.

[Means for Solving the Problems] As shown in FIG. 1 showing an embodiment of the present invention, the present invention includes an oil level detection switch 12 that closes when the oil level of the internal combustion engine becomes less than the allowable lower limit level; The output voltage V11 of one half cycle is applied as a forward voltage to both ends of a power supply coil 3a that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine and drives the internal combustion engine ignition device with the output V11 of one half cycle. a trigger circuit 20 that supplies a trigger signal to the gate of the engine stop thyristor 7 to make the engine stop thyristor conductive when the oil level detection switch 12 is closed; In an internal combustion engine stop device equipped with a trigger circuit 20, the trigger circuit 20 is improved to achieve the above object.

In the present invention, the trigger circuit 20 includes a series circuit of a resistor 21 and a capacitor 22 connected between the anode and gate of the engine stop thyristor 7, and a trigger control transistor switch 23. Trigger control transistor switch 23
The collector-emitter circuit is connected in parallel to the gate and cathode of the engine stop thyristor 7, and the power supply coil 3a is connected to the capacitor 22.
The base is coupled to the capacitor 22 so that a base current is applied through the capacitor 22 to conduct, and when the power supply coil 3a is in a cut-off state, the capacitor 22 is connected to the power supply coil 3a.
A trigger signal is allowed to be supplied to the thyristor 7 through the resistor 21 and the resistor 21 . The oil level detection switch 12 is connected between the base and emitter of the trigger control transistor so as to shut off the trigger control transistor switch 23 when the oil level falls below the allowable lower limit level and is closed.

[Operation of the invention] In the above configuration, when the oil level is above the allowable lower limit level, the oil level detection switch 12
When the transistor switch 23 is open, when the ignition power supply coil 3a induces a half-cycle voltage contributing to the ignition operation, a base current flows through the capacitor 22 to the transistor switch 23, making the transistor switch conductive. Therefore, transistor switch 2
3 becomes conductive, shorting the gate and cathode of the engine stop thyristor 7. Therefore, no trigger signal is applied to the thyristor 7 and it cannot conduct. When the charging of the capacitor 22 is completed, the base current no longer flows through the transistor switch 23, so that the transistor switch 23 is cut off. Since the ignition power supply coil 3a is not short-circuited at this point, the ignition operation is performed without any problem and the engine rotates normally. When the transistor switch 23 is turned on, the series circuit of the capacitor 22 and the resistor 21 can reduce the rate of change (dv/dt) of the voltage applied between the anode and cathode of the thyristor 7. can be protected from rates. Therefore, there is no need to separately connect a series circuit of a capacitor and a resistor to both ends of the thyristor 7, and the circuit configuration can be simplified.

When the oil level falls below the allowable lower limit level and the oil level detection switch is closed, the transistor switch 23 cannot conduct, so when the ignition power supply coil 3a induces a half-cycle voltage contributing to the ignition operation, the capacitor 22 A trigger signal is supplied to the thyristor 7 through the thyristor 7, and the thyristor 7 becomes conductive. Therefore, this thyristor 7 short-circuits the ignition power supply coil and prevents the ignition operation.

In the device of the present invention, the trigger signal is supplied to the engine stop switch with a half-cycle output that contributes to the ignition operation of the ignition power coil, so the present invention does not contribute to the ignition operation of the power coil within the ignition device. It can also be applied when the half-cycle output is short-circuited.

[Embodiments] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which the trigger 20 of the engine stop switch 7 is
A resistor 2 whose one end is connected to the gate of the thyristor 7
1, a capacitor 22 connected between the other end of the resistor 21 and the anode of the thyristor 7, a transistor switch 23 consisting of an NPN transistor whose collector and emitter are connected to the gate and cathode of the thyristor 7, respectively; 23 base and capacitor 22 resistance 2
1 side terminal, and a diode 25 connected in parallel between the collector and emitter of the transistor switch 23. The other points are constructed similarly to the apparatus shown in FIG.

In Fig. 1, the primary coil (power supply coil) 3a of the ignition coil is synchronized with the rotation of the engine, and as shown in Fig. 2, a half-cycle voltage V which contributes to the ignition operation is applied.
11 and half-cycle voltage V that does not contribute to ignition operation
12 is generated. Oil level detection switch 1
When a half-cycle voltage V11 contributing to the ignition operation is generated with the transistor 2 open, a base current flows to the transistor switch 23 through the capacitor 22 and the resistor 24, thereby making the transistor switch 23 conductive. Therefore, the transistor switch 23 short-circuits the gate and cathode of the thyristor 7, thereby preventing the trigger signal from being supplied to the thyristor 7. Therefore, when the oil level detection switch 12 is open, the thyristor 7 is not conductive, and the ignition operation of the engine is performed without any problem. The transistor switch 23 is the capacitor 22
When the charging is completed, it will be in the cut-off state.

On the other hand, when the oil level falls below the allowable lower limit level and the oil level detection switch 12 closes, the transistor 23 cannot conduct, so when the half-cycle voltage V11 that contributes to the ignition operation occurs, the capacitor 2 A trigger signal is applied to the thyristor 7 through the thyristor 7, and the thyristor 7 becomes conductive. 1 when thyristor 7 conducts
Since the secondary coil 3a is short-circuited, the ignition operation is blocked and the engine misfires. As long as the oil level is below the allowable lower limit level and the oil level detection switch is closed, the thyristor 7 becomes conductive every time the half-cycle voltage V11 used for ignition operation is generated and continues to prevent the ignition operation. The engine stops and prevents the engine from seizing and being damaged due to insufficient oil level.

Figure 3 shows another embodiment of the present invention.
In this embodiment, a capacitor 27 is connected between the gate and cathode of the engine stop thyristor 7 via a resistor 26, and a connection point between the capacitor 27 and the resistor 26 is connected via a diode 28 to the collector of a transistor switch 23. . In other respects, the structure is similar to that of the embodiment shown in FIG.

In the embodiment of FIG. 3, once the thyristor 7 becomes conductive, the capacitor 27 is charged through the resistor 26 by the gate-cathode voltage of the thyristor 7. The charge in the capacitor 27 is discharged between the resistor 26 and the gate cathode of the thyristor 7, so that a firing signal is applied to the thyristor 7. Therefore, when the oil level detection switch 12 closes once and then reopens, the transistor switch 23 is activated when a half-cycle voltage V11 contributing to the ignition operation is generated.
An ignition signal is given to the thyristor 7 even when the thyristor 7 is conductive. Therefore, once the oil level detection switch 12 is closed, as long as the engine is rotating and a voltage is induced in the primary coil 3a, the thyristor 7 is repeatedly turned on to stop the engine.

In the example shown in FIG. 1, the engine will not stop unless the oil level detection switch 12 remains closed, but in the embodiment shown in FIG. Since the system is stopped, the protection of the institution can be ensured completely.

FIG. 4 shows still another embodiment of the present invention, in which a small resistor 30 is provided on the cathode side of the engine stop thyristor 7 and connected in series with the thyristor. A capacitor 32 is connected to both ends of 30 via a diode 31. A light emitting diode 34 is connected to both ends of the capacitor 32 via a resistor 33.

In the embodiment shown in FIG. 4, when the oil level falls below the allowable lower limit level and the engine stop thyristor 7 becomes conductive, a voltage appears across the resistor 30.
This voltage charges capacitor 32 to the polarity shown. Since the voltage across capacitor 32 is applied to light emitting diode 34, light emitting diode 34 emits light to indicate that the oil level has fallen below an acceptable lower limit level. If it is possible to display that the oil level has fallen below the permissible lower limit level, it will be possible to know the reason why the engine has stopped, allowing for quick and reliable measures to be taken against oil level abnormalities. can.

In the above embodiment, at least the primary coil 3a of the ignition coil 3 of the ignition device 1 for an internal combustion engine is disposed in a generator driven by the engine, and the primary coil 3a also serves as a power supply coil. However, it goes without saying that the present invention can be similarly applied to cases where the ignition coil is placed outside the generator and the power supply coil is placed inside the generator.

In the above embodiment, a current interrupt type ignition device is used, but the present invention can also be applied to a case where a capacitor discharge type ignition device is used.

[Effects of the invention] As described above, according to the invention, since the oil level detection switch is connected between the base and emitter of the transistor switch, an inexpensive oil level detection switch with low withstand voltage can be used. In addition, a series circuit of a resistor and a capacitor provided in the trigger circuit of the engine stop thyristor can protect the engine stop thyristor from an excessive rate of voltage change. There is no need to connect them separately. Therefore, the number of parts can be reduced and the circuit configuration can be simplified.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a waveform diagram showing an example of a voltage waveform induced by a power supply coil, and Figs. 3 and 4 respectively show other different embodiments of the present invention. The circuit diagrams shown in FIGS. 5 and 6 are circuit diagrams showing different conventional examples, respectively. 1... Ignition device for internal combustion engine, 2... Internal combustion engine stop device, 7... Thyristor for engine stop, 12...
Oil level detection switch, 20...Trigger circuit, 21...Resistor, 22...Capacitor, 23...
...transistor switch.

Claims (1)

[Claims for Utility Model Registration] An oil level detection switch that closes when the oil level of an internal combustion engine falls below the permissible lower limit level, and an alternating current voltage that is induced in synchronization with the rotation of the internal combustion engine to output one half cycle. an engine stop thyristor connected to both ends of a power supply coil that drives an ignition device for an internal combustion engine in such a way that the output voltage of the one half cycle becomes a forward voltage; An internal combustion engine stopping device comprising a trigger circuit that supplies a trigger signal to a gate of an engine stopping thyristor to make the engine stopping thyristor conductive, wherein the trigger circuit is connected between an anode gate of the engine stopping thyristor. A series circuit of a resistor and a capacitor, and a collector-emitter circuit are connected in parallel to the gate cathode of the engine stop thyristor, and a base current is applied from the power supply coil through the capacitor to establish conduction. a trigger control transistor switch having a base coupled to the capacitor and allowing a trigger signal to be supplied from the power supply coil to the thyristor through the capacitor and the resistor when in a cut-off state; An internal combustion engine stopping device characterized in that an oil level detection switch is connected between the base and emitter of the trigger control transistor so as to cut off the trigger control transistor switch when the oil level detection switch is closed.