JPS6036794Y2 - Plasma igniter for internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a plasma ignition device for an internal combustion engine, and particularly relates to a safety function when the engine stalls (so-called engine stall).

FIG. 1 is a schematic diagram of an example of a conventional plasma ignition device.

In Figure 1, ignition coil 3, contact point 4
etc. are a normal spark discharge ignition system, which includes a booster 7 (for example, a DC-DC converter), a capacitor 8, and an inductor 9.
is an ignition system for plasma.

And at the time of ignition, 10 to 2 given from the ignition coil 3
When a spark discharge occurs in the ignition plug 10 due to a high voltage of 0 kV, the insulation of the discharge space is broken and a state is created in which discharge is possible even at a relatively low voltage of 2 to 3 kV, and as a result,
The electric charge stored in the capacitor 8 of the plasma ignition system causes the discharge to continue for the necessary time.

The high-temperature, high-energy plasma-like gas produced by this discharge generates a large number of flame kernels in the air-fuel mixture in the combustion chamber, and even a lean air-fuel mixture is reliably ignited.

In the conventional plasma ignition system as described above, the key switch 2 (the main switch of the car)
(battery) is connected to both the spark discharge ignition system and the plasma ignition system.

Therefore, even if the engine is not running, as long as the key switch is turned on (for example, when the engine stalls), the plasma ignition system is operating.

However, the electric charge stored in the capacitor 8 of the plasma ignition system is approximately several joules per ignition, which is quite high energy, and the voltage is 2 to 3 kV, so it is extremely dangerous if the human body should come into contact with it. .

In particular, engine stalls often occur when the engine is malfunctioning for some reason, so there is a high possibility that the driver or the like will inspect the engine part, and there is therefore a high risk of receiving an electric shock.

Furthermore, since the plasma ignition system uses high energy as described above, the capacity of the booster 7 is also quite large, about 100 to 300W.

Therefore, even when there is no load, the power consumption due to the loss of the transformer in the booster 7 cannot be ignored.

Especially when the engine stalls, the amount of power generated drops to zero and all power is supplied from the battery, which increases the burden on the battery.
In this case, the fuel efficiency will also be reduced.

The present invention was developed focusing on the above problem, and detects a state in which the engine is not rotating even though the key switch is on (a so-called engine stall state), and in that state, boosts the pressure of the plasma ignition system. An object of the present invention is to provide a plasma ignition device which eliminates the risk of electric shock and prevents wasteful consumption of electric power by being configured to stop the device.

The present invention will be explained in detail below based on the drawings.

FIG. 2 is a circuit diagram of an embodiment of the present invention.

In FIG. 2, 11 is a rotation sensor, 12 is a discrimination circuit,
13 and 14 are switches, and the same reference numerals as in FIG. 1 indicate the same parts.

The rotation sensor 11 is, for example, a crank angle sensor consisting of a disk interlocked with the engine's crankshaft and an electromagnetic pickup, and receives a pulse signal S with a frequency proportional to the engine's rotation speed.
Outputs 1.

The determination circuit 12 inputs the pulse signal S□, determines whether or not the engine is rotating, and outputs a determination signal S2.

The switches 13 and 14 are, for example, relays, and when the discrimination signal S2 indicates that the engine is rotating (for example, "0"), the switch 13 is turned on and the switch 14 is turned off.

Further, when the discrimination signal S2 indicates that the engine has stopped (for example, '1
”), the switch 13 is turned off and the switch 14 is turned on.

Therefore, when the engine stops, even if the key switch 2 is on, the switch 13 is turned off and the power to the booster 7 is turned off.

At the same time, the switch 14 is turned on, so that the charge stored in the capacitor 8 is discharged.

Therefore, even if the engine stalls, the plasma ignition system immediately stops boosting operation, eliminating the risk of electric shock during inspection, and also preventing wasted power consumption due to no-load current of the transformer in the booster. I can do it.

Next, FIG. 3 is a circuit diagram of one embodiment of the discrimination circuit 12.

In FIG. 3, capacitor C1 is charged from a power source via resistor R3.

However, when the pulse signal S□ of the rotation sensor 11 is applied, the transistor Q1 turns on and discharges the charge of the capacitor C□, so while the pulse signal S1 is continuously applied, the terminal voltage of the capacitor C1 is .

does not rise.

When the engine stops and the pulse signal S1 stops, the terminal voltage V of the capacitor C1.

increases with a time constant determined by R3 and C1, and its value is the reference voltage V, (the value obtained by dividing V, , by R□ and R2)
When the value exceeds 1, the output of the comparator 15, that is, the discrimination signal S2 becomes 1.
Become ゛.

Therefore, in the circuit of FIG. 3, the discrimination signal S2 is 1
゛ indicates that the engine is stopped, and 0° indicates that the engine is rotating.

Next, FIG. 4 is a diagram showing another embodiment of the present invention, in which portions 3 to 6 and 9 to 10 are the same as those in FIG. 2, so illustration thereof is omitted.

In the embodiment shown in FIG. 4, when a DC-DC:7 inverter 16 is used as the booster 7, the boosting operation is stopped by grounding the switching signal of the DC-DC converter.

The DC-DC converter 16 includes an oscillator 17 and a transformer 18
, switching transistor Q2. It consists of Q3 and a rectifying diode D3.

Transistors Q2 and Q3 are turned on alternately by the constant frequency switching signal output from the oscillator 17, and as a result, current alternately flows from the power source 1 to the primary winding of the transformer 18, causing the secondary winding to It outputs a high voltage boosted to .

In the above circuit, when the engine is stopped, the discrimination signal S2 is “°
1, transistor Q turns on, so transistor Q2. The base of Q3 is the diode D1. Grounded via D2.

Therefore, transistor Q2. Since Q3 is always off and no current flows through the primary winding of transformer 18,
Boosting operation stops.

Note that the above explanation exemplifies the case where the present invention is applied to a plasma ignition device equipped with an ignition system for spark discharge and an ignition system for plasma; The present invention can be similarly applied to an apparatus in which the spark discharge ignition system is omitted.

As explained above, according to the present invention, the function of the booster is stopped when the engine stalls, so there is no risk of electric shock during inspection, and wasteful consumption of power can be prevented.

[Brief explanation of the drawing]

Fig. 1 shows an example of a conventional plasma ignition device, Fig. 2 shows an embodiment of the present invention, Fig. 3 shows an example of a discrimination circuit, and Fig. 4 shows another embodiment of the present invention. be. Explanation of symbols, 1...Power supply, 2...Key switch, 3...Ignition coil, 4...
Contact point, 5, 6... Diode,
7...Booster, 8...Capacitor, 9
...Inductor, 10... Spark plug, 11... Rotation sensor, 12... Discrimination circuit, 13, 14... Switch, 15・・・・・・
...Comparator, 16... -DC converter, 1
7...Oscillator, 18...Transformer.

Claims (1)

[Claims for Utility Model Registration] 1. A plasma ignition device equipped with at least a booster that generates a high voltage for plasma ignition, which is inserted between a power source and the booster, a key switch is turned on, and a first means for detecting a state in which the engine is stopped;
A second device that stops the function of the booster when the above condition occurs.
A plasma ignition device for an internal combustion engine, characterized in that the function of the booster is stopped when the engine stalls. 2. Utility model registration claim 1, wherein the first means comprises a rotation sensor that outputs a signal synchronized with engine rotation, and a discrimination circuit that determines that the engine has stopped when the signal stops. Plasma ignition device for an internal combustion engine as described in . 3. The second means is a switch inserted between the power supply and the booster, and is configured to turn off the switch when the first means detects the above state. A plasma ignition device for an internal combustion engine according to claim 1 of the utility model registration claim. 4. The booster is an X-converter comprising a transformer, an oscillator, and a switching element that switches the primary current of the transformer on and off according to the output of the oscillator, and the second means is connected to the output terminal of the oscillator. The internal combustion engine according to claim 1, wherein the internal combustion engine is a switch inserted between grounding and is configured to turn on the switch when the first means detects the above state. plasma igniter. 5 The second means is a first switch inserted between the power supply and the booster, and a second switch inserted between the output terminal of the booster and ground, and the first means is the first switch inserted between the power supply and the booster. the first switch is turned off and the second switch is turned off when the state of
A plasma ignition device for an internal combustion engine according to claim 1, characterized in that the plasma ignition device for an internal combustion engine is configured to turn on a switch.