JPS5835271A - Ignition device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To reduce the transmission energy to an ignition plug, to stabilize the ignition of the dilute air-fuel mixture, and to improve the fuel consumption by boosting the battery voltage with a DC-DC converter and by storing the high voltage in high voltage condensers for individual cylinders so as feed it directly to an ignition plug at a preset time. CONSTITUTION:The output voltage of a battery B is boosted to 1KV with a DC-DC converter and is fed to ignition circuits F1-F4. The input high voltage is charged in high voltage condensers C1-C4. When an ignition time designation signal (f) is fed into a circuit A, an ignition signal (a) is fed out at the preset time for the first cylinder, and a semiconductor switch S1 is made conductive. As a result, the potential of the output terminal Q of the condenser C1 is rapidly changed, and the change is fed to an auxiliary condenser C1', thereby a transient phenomenon occurs in the primary circuit, and a damped AC voltage at a frequency f1 is generated across the terminals of a coil Lp. This voltage is boosted by a step-up transformer to induce the high voltage across the secondary winiding, and the high voltage is applied to an ignition plug P1 to discharge it, then the high energy of the condenser C1 flows through the secondary winding and is fed into the ignition plug P1 in a short time.

Description

[Detailed description of the invention] The present invention relates to improvements in ignition devices for internal combustion engines.

An example of a conventional ignition device is the one shown in FIG. The current 11 flowing from the battery 1 constituting the DC power supply to the primary coil L1 of the ignition coil 2 is intermittent at a contact point 3 that opens and closes in synchronization with the rotation of the engine, and the current 11 flowing from the battery 1 constituting the DC power supply to the primary coil L1 of the ignition coil 2 is intermittent at a contact point 3 that opens and closes in synchronization with the rotation of the engine. A high voltage pulse vh'lk- having a peak value of 1 On is generated.

Then, this high-pressure pulse vh is applied to the distributor 4 and distributed to each cylinder by the distribution action of the rotor r rotating in synchronization with one engine rotation. Therefore, the distributed high voltage pulse vh is supplied to each spark plug 6a to 6d in the order of 6a → 6b → 6c → 6d via high tension cords 5a to 5d, and the engine is powered by #1 → #3 → Reference 4 → #. Ignition (ignition) with a fist of two cylinders, t! ! I was trying to let it burn.

However, in such a conventional ignition system, the battery 1
After energy is stored in the primary coil L1 of the ignition coil 2, it is transmitted to the secondary coil Ls, which is further transmitted to the distributor 4 and the high-speed cables 5a to 5.
Since the energy had to be supplied to each of the spark plugs 6a to 6d via the battery 1, there was a drawback that the energy transmission loss from the battery 1 to the spark plugs 6a to 6d was as large as 80 to 90%. Unfortunately, due to the power consumption of the battery 1 and the structure of the ignition coil, it is not possible to increase the discharge energy of the ignition plugs 6a to 6d.

For example, it is difficult to stably ignite (ignite) a lean mixture of 218% and burn it hot.

There were limits to how much fuel efficiency could be improved. Incidentally, the maximum value of conventional discharge energy was about 50 FiJ.

The present invention has been made in view of the above, and it is possible to convert relatively low DC power supply voltage provided by a battery or the like into DC-DC.
The converter boosts the voltage to a high voltage of several a, which is necessary to discharge the ignition plug, and stores this in a high voltage capacitor for each cylinder.The ignition energy charge of several 100 mJ stored in this capacitor is directly injected into the ignition plug at a predetermined time. By doing so, the energy transmission loss to the spark plug is greatly reduced and the discharge energy is increased without causing an increase in the power consumption of the battery.
The purpose is to stabilize the ignition and combustion of lean air-fuel mixtures and improve the fuel efficiency of the engine.

The present invention will now be described with reference to illustrated embodiments.

FIG. 2 is a circuit diagram of the overall configuration showing one embodiment of the present invention, in which a DC voltage booster increases the output voltage (for example, 12 cm) of battery B constituting the DC power supply to a high DC voltage (for example, IKV).
- The output terminal of the DC converter D is connected to the same number of high-pressure ignition circuits F1 to F4 as the number of cylinders of the engine. Since the high-pressure ignition paths F1 to F4 are constructed in exactly the same way, a circuit for supplying discharge energy to the first cylinder spark plug P1 will be described as a representative example.

First, the -1000 terminal of a high voltage capacitor C1 with a capacitance of 0.5 μF is connected to the output terminal of the DC-DC converter D through a diode DI1, and a semiconductor switch Lt' is connected between this terminal and the ground. I am wearing it. or.

The other terminal of the high-voltage capacitor C1 is connected to one terminal of the step-up transformer T, the primary coil Lp, and the secondary coil Ls, and an auxiliary diode D11 is interposed between this connecting terminal and the ground. are doing.

On the other hand, an fj auxiliary capacitor C1/ having a smaller capacitance (for example, 0.2 μF) than the high voltage capacitor C1 is interposed between the other terminal of the primary coil Lp of the boost transistor and the ground. And the secondary coil L
The other terminal of the spark plug P1 is connected to the center electrode of the spark plug P1, and the side electrodes of the spark plug P1 are grounded.

The semiconductor switch S0 is composed of, for example, a high voltage thyristor, a field effect transistor, etc., and receives an ignition timing designation signal f output from a breaker point (not shown).
This semiconductor switch S0 is made conductive only when the ignition signal a is output from the ignition signal generating circuit A which inputs the ignition signal a. Incidentally, the ignition signal generation circuit consists of, for example, a ripple binary power counter and a monostable multi-capacitor, and each time the ignition timing designation signal f is supplied, it generates the ignition signal a to d within a predetermined range (for example, 0.5m8). are output to the gates of the semiconductor switches S□ to S4 in a predetermined order.

Next, the operation of the ignition system with the above configuration will be explained.

t 2V I current electric pressure 4t output from battery B
It is boosted to a direct current voltage of IKv by a DC-DC converter D and input to each ignition circuit F1 to F4.

The high voltage input to the ignition circuits F1 to F4 in this way is passed through the high voltage capacitor C1 through the diodes D1 to D4.
~C4 are charged respectively.

- 10,000, When the ignition timing designation signal f is input to the ignition signal generation circuit in synchronization with the engine rotation, “
The ignition signals B-, -, d with a pulse width of 0.5F718, which are at the 1'' level, are output in sequence. The semiconductor switches 51x84 of the high-voltage ignition circuits F1-F4 become conductive, and as a result, the input terminals of the high-voltage capacitors C4 are grounded, so that the potential of the input terminals suddenly drops from IK'V to Ov. Then, capacitor C1
In order to maintain the potential difference between both terminals of ~C4, the potential of the output terminal Q suddenly changes from 0■ to -IKV.

Such a change in the potential at point Q causes step-up transformers T1 to T4.
Auxiliary capacitor C1/-'
-C,/, this auxiliary capacitor C1/~C
In the primary side circuit composed of 4/ and 1 medical coil Lp
A transient phenomenon accompanied by a damped oscillation of 1 is generated, and a damped oscillating AC voltage with a frequency f1 having a maximum amplitude of ±IKv is generated between the terminals of the 1st medical coil Lp. Then, this voltage
? ,"l'+'-'I'4◆-ratio 1;Ndo↓'
] Since the voltage is boosted by N times and vI is generated on the secondary side, an AC voltage with a maximum amplitude of ±NKV is applied to the center electrodes of the % ignitors P1 to P4.

As described above, when a high voltage is applied to the center electrodes of the spark plugs P1 to P4, the mixture existing between the center electrode and the side electrodes is dielectrically broken down, and the spark plugs P1 to P4 become conductive (discharged). let When the spark plugs P1 to P4 become conductive in this way, about 2
50FXJ's high voltage and high energy step-up transformers T1 to T4
It flows through the secondary circuit consisting of the secondary coil Ls and the high-voltage capacitors 01 to C4, and is injected into the center electrode of the ignition t&P1 to P4 within about 0.2 m8 time.

Due to this injection of high energy, plasma-like gas is ejected from the discharge space of each spark plug P1 to P4 into the combustion chamber, so that even a lean mixture of "Y2ZO" can be stably ignited (ignited).
, it will burn.

FIG. 3 shows the ignition timing designation signal f, the ignition signals a to d, and the discharge voltages Vsl to Vs4 applied to the spark plugs PI-P4.
FIG.

The discharge waveforms of the spark plugs P1 to P4 are shown in FIG. Here, Vs is the discharge voltage, Is is the discharge current, and P
d indicates discharge power.

On the other hand, the discharge energy Es is as follows: Es=foPd@dt However, in to 160μ8=1.
Since it is given by 6 cutting O8, it becomes 15071 J during ES, and the discharge time T, 24 μs is an alternating current arc discharge similar to that of the conventionally known CDI ignition system, and the discharge time T2
136μs is 1. This is an arc discharge in which a large current with a peak value of Ip240A flows, and the discharge duration is approximately 16
It turns out that it is 0 μs. Therefore, the conventional ignition system
~5 times higher energy than conventional equipment (1~2m5)
The fuel is injected in such a short period of time, and this high energy allows the lean mixture to be ignited and combusted in a stable manner.

Also, the efficiency ηo of D C-D C near 7verter D: 80
X, and the efficiency ηf of the high voltage ignition circuits F1 to F4 is.

Therefore, the overall efficiency ηT is.

ηT=η0×ηf+50%.

For this reason, although the discharging energy Es can be increased, the dissipating power of the battery B can be maintained at approximately the same value as in the conventional device, so there is no fear that the battery load will become excessive.

No. 5- is a circuit diagram of the overall configuration showing another embodiment of the present invention.

In this embodiment, one end of one primary coil Lp of each step-up transformer Tl to T4 is grounded, and high voltage auxiliary capacitors C11 to C4I are shared, and a high voltage diode D1 is used to isolate the cylinder %lJ. The cost is reduced by adding ~D:, and the rest is the same as the previous embodiment.In addition, in this way, the auxiliary capacitor
In case of standardization, 1. As shown in the figure, capacitor C
It is desirable to add a resistor R in parallel to ', so that the capacitor C is discharged to the voltage Ov between its terminals until the ignition timing of the primary cylinder.

As explained above, according to the present invention, the DC power supply voltage supplied from ) (Tet 1) etc. is boosted to a high voltage by a DC-DC converter and stored in a high voltage capacitor for each cylinder. Since the stored energy is directly injected into the ignition plug at a predetermined ignition timing, the efficiency of the ignition system is improved. For this reason, the discharge energy can be increased without causing an increase in power consumption, so even lean mixtures can be stably ignited and combusted. l! Fuel efficiency, exhaust performance, etc. can be greatly improved. In addition, since electrical contacts and mechanical moving parts such as distributors are not required, there is no need to maintain the ignition system, which improves the reliability of this type of ignition system and reduces maintenance costs. Can be reduced.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional example, Figure 2 is a circuit diagram of an embodiment of the present invention, Figure 3 is a signal waveform diagram of each part of the second circuit, Figure 4 is a discharge waveform diagram, and Figure 5 is a diagram of the present invention. FIG. 3 is a circuit diagram of another embodiment of the invention. A...Ignition signal generation circuit B...Batch IJ
C1~C4...&JE resistance condenser tD...DC-
DC Konno Nita D1~D4...Diode 8
1~S4...Semiconductor switch T1~T4...
Step-up transformer Lp...Primary side coil Ls...2
Next side coils P1 to P4...Spark plug patent member Fujio Sasashima, Patent attorney, Nissan Motor Co., Ltd.

Claims (1)

[Claims] A DC-DC converter that boosts the DC power supply voltage to a high DC voltage, a high-voltage capacitor for each cylinder with one terminal connected to the output end of the DC-DC converter, and a DC-DC converter connection side of each high-voltage capacitor. Semiconductor switches of the same number as the number of cylinders are inserted between the terminal and ground and become conductive only at the ignition timing of the corresponding cylinder, and a primary coil and a secondary coil are connected to the other terminal of each high voltage capacitor. A step-up transformer whose one terminal is connected to the same number as the number of cylinders, and a spark plug whose one electrode is connected to the output end of the secondary coil of each step-up transformer and whose other electrode is grounded, An ignition device for an internal combustion engine, characterized in that the ignition energy charge stored in the high voltage capacitor is injected into the ignition plug at a predetermined timing.