JPH0322551Y2 - - Google Patents

Description

[Detailed description of the invention] "Purpose of the invention" (Field of industrial application) The invention relates to an ignition device used in gasoline engines, and in particular to an ignition device that can supply powerful ignition energy to a spark plug. Regarding equipment.

(Prior art) Traditionally, the so-called Kettering system has been the mainstream ignition system for gasoline engines, but in recent years, ignition performance has been improved by generating multiple sparks in succession during one explosion stroke. something is proposed.

Such a continuous ignition type can improve startability, output, fuel efficiency, and drivability, but the primary voltage applied to the primary side of the ignition coil is 12V or more, similar to the conventional Kettering type.
Since it is 14V, the excitation time of the ignition coil is shortened, especially in the high speed range, and the spark energy for each shot is about the same. That is, Figure 3A shows the ignition spark waveform by the Kettering method, and the discharge current is 60mA and the discharge time is 1.5mS.
That's about it. On the other hand, the continuous ignition method shown in Figure 3B can extend the discharge time to about 2.5 mS, but the peak value gradually attenuates from a maximum value of 60 mA, so the mixture cannot be completely ignited. There were cases where this was not possible, and there was a problem that the advantages could not be fully demonstrated.

(Problems to be solved by the invention) The present invention solves the above-mentioned problems such as mis-ignition in the conventional system, and greatly improves startability, output, fuel efficiency, and drivability by reliably and completely igniting the air-fuel mixture. An object of the present invention is to provide an ignition device for an internal combustion engine that can be improved in the following manner.

"Structure of the invention" (Means for solving the problems) The ignition device for an internal combustion engine according to the invention continuously ignites the spark plug by rapidly switching the primary voltage applied to the ignition coil. a high-speed switching section, a DCDC converter section for boosting the power supply voltage from the battery, and selectively switching whether the power supplied to the ignition coil is obtained via the DCDC converter or directly from the battery. It is equipped with a control unit that can control the above switching by an external signal such as engine speed, and by supplying a high voltage to the primary side of the ignition coil. It is designed to produce powerful continuous sparks.

(Example) An example of the ignition device for an internal combustion engine according to the present invention will be described based on FIGS. 1 and 2.

In the figure, reference numeral 1 denotes a high-speed switching section, which includes a separately excited oscillation circuit 11 and a switching circuit 12 controlled by the separately excited oscillation circuit 11. Apply an intermittent pulse to the primary side L ₁ of the ignition coil L, and apply an intermittent pulse to the secondary side L ₂
The plug P is configured to generate continuous high voltage pulses to ignite the plug P. The separately excited oscillation circuit 11 receives signals relating to the crank angle and rotational speed from the engine E in order to optimize the timing and length of pulse generation.

2 is a DCDC converter unit for boosting the power supply voltage of battery B, and includes a main switching circuit 21, a rectifier circuit 22, an error amplifier 23, a control signal generation circuit 24, and a bypass diode 25. Main switching circuit 2
The power supply DC voltage pulsed in step 1 is stepped up by a transformer (not shown), rectified and smoothed by a rectifier circuit 22, and then input to the primary side _L1 of the above-mentioned ignition coil L. The high-speed switching section 1 is used in common, and switching is performed depending on whether or not the common ground end G of the ignition coil L is connected to the ground GND. Furthermore, even if the output voltage of the DCDC converter section 2 is abnormally reduced due to a failure or the like, the bypass diode 25 bypasses the power from the battery B and supplies it to the ignition coil L, thereby preventing situations such as engine stoppage. It is provided for.

3 is designed to be able to selectively switch the power supplied to the ignition coil to be obtained via the DCDC converter 2 or directly from the battery B, and can be controlled by an external signal such as the engine speed. This is a switching unit capable of controlling the above switching, and in the embodiment, a waveform shaping circuit 31 for shaping the rotational speed signal from the engine E, and a frequency-voltage conversion circuit provided at the subsequent stage. 32, a voltage comparison circuit 34 provided at the subsequent stage for comparing the voltage from the frequency-voltage conversion circuit 32 and the reference voltage from the high-precision reference voltage generation circuit 33; and a voltage comparison circuit 34 in the high-precision reference voltage generation circuit 33 It is composed of an operating point setting circuit 35 that can set a reference voltage to an arbitrary value, and a control signal C for controlling the control signal generation circuit 24 is output from the voltage comparison circuit 34. It is becoming more and more common. The control signal generation circuit 24 receives the control signal C.
The DCDC converter 2 is activated, and specifically, when the rotation speed of the engine E increases, the output voltage from the frequency-voltage conversion circuit 32 is lower than the reference voltage in response to a signal from a rotation sensor, etc. is set so that the output signal C of the voltage comparator circuit 34 becomes high level. The control signal generation circuit 24 turns on in response to the output trigger signal C, and a voltage boosted to about 18V to 22V is output from the output terminal H of the DCDC converter section 2, and this is passed through the balance resistor R. The primary side of the above ignition coil L
Applied to L ₁ . The higher the output voltage of the output terminal H, the more the excitation energy of the ignition coil increases, and a stronger ignition spark can be obtained. However, since the internal resistance of the ignition circuit system is constant, the primary
Since the amount of heat generated increases in proportion to the _L1 input voltage, the error amplifier 23 regulates the output terminal H voltage to the above-mentioned appropriate value to balance efficiency and safety.

The reference voltage of the high-precision reference voltage generation circuit 33 can be externally set to an arbitrary value by the operating point setting circuit 35. For example, by installing a volume type variable resistor inside the vehicle, the reference voltage can be set to any value from the outside by using the operating point setting circuit 35. It is also easy to control the voltage, and with such a configuration, the engine rotation speed at which the DCDC converter section 2 starts operating can be controlled, for example, from 1000 RPM to
It can be set arbitrarily within the range of 5000RPM.
Further, the operating point setting circuit 35 is not limited to the above example,
It can be linked to the operation of the starter motor, outside air temperature, cooling water temperature, exhaust gas temperature, intake air amount, etc.
It is also easy to control according to atmospheric pressure, back pressure, vehicle speed, etc., and it is possible to ignite accurately under all conditions. In addition, the above DCDC converter section 2
While operating, the power consumption of battery B is
However, if strong ignition is not required, power consumption can be suppressed by using the operating point setting circuit 35 to increase the engine speed at which the DCDC converter section 2 operates beyond the normal range. I can do it.

Figure 2 is a graph showing the relationship between the discharge current and discharge time of the spark plug P when using the ignition system for an internal combustion engine detailed above.The first high-voltage pulse after the start of discharge has a peak value of 80mA. ,
More than 1.3 times more energy can be obtained compared to the conventional Kettering type ignition system. What's more, it has a discharge duration of 3.5mS and generates three times as much energy overall compared to conventional continuous ignition type ignition devices, and the synergistic effect of these produces extremely powerful ignition energy. . Therefore, the air-fuel mixture in the cylinder can be rapidly combusted, which not only improves output and fuel efficiency, but also suppresses the generation of harmful substances.

"Effects of the Invention" According to the ignition device for an internal combustion engine according to the present invention, the spark plug can be ignited continuously, and the spark energy can be greatly improved in both the discharge current and the discharge time. In addition, since it can be operated as a conventional continuous ignition device by being switched as desired by an external signal such as the engine speed, it can be used efficiently as needed. By improving ignitability in this way, it is possible to greatly improve startability, output, fuel efficiency, and drivability, and it also has excellent effects such as suppressing the emission of harmful substances. There is.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the ignition system for an internal combustion engine according to the present invention, FIG. 1 is a block diagram, FIG. 2 is a graph showing the relationship between discharge current and discharge time in a spark plug, and FIG. FIG. 3 is a graph showing the relationship between discharge current and discharge time in a spark plug of a conventional ignition device for an internal combustion engine. 1...High speed switching section, 2...DCDC converter section, 3...Switching section, L...Ignition coil, P...Spark plug.

Claims (1)

[Scope of utility model registration request] a high-speed switching section for continuously igniting a spark plug by rapidly switching a primary voltage applied to an ignition coil;
For boosting the power supply voltage from the battery
It is possible to selectively switch whether the power supplied to the DCDC converter section and the ignition coil is obtained via the DCDC converter or directly from the battery, and the above switching can be made by an external signal such as the engine rotation speed. An ignition device for an internal combustion engine, characterized in that the ignition device is equipped with a switching section configured to control the ignition system.