JPS6038064Y2 - ignition device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a novel ignition device using a nonlinear dielectric element.

The circuit configuration of a conventional ignition device known as an ignition device for automobiles is shown in FIG. 1 and will be described.

This ignition device consists of a transistor-type high-voltage, high-frequency generator (■), a rectifier (■), a high-voltage power storage (■), and an SCR (
When the ignition switch SW is turned on, the voltage of the battery BATT changes to the two transistors Tr□ of the high-voltage, high-frequency generator (■).

Tr2 and divider RD1. It is biased in the positive direction via RD2, and the transistor with the higher gain turns on quickly, causing a saturated current to flow instantly.
At the next moment, 5hutt-off occurs, and at the same time, saturation current flows to other transistors, and 5hutt-off immediately occurs.
The flip-flop operation is repeated to generate oscillation, and an oscillation output with a constant frequency is obtained.

This oscillation output is full-wave rectified in the rectifier section (2), converted into a DC signal, and stored in the high-voltage power storage section (4).

This charge is maintained until the SCR is made conductive by an impulse.

On the other hand, in the trigger impulse generating part ■, when the point (POINT) that is controlled to turn on and off according to the rotation of the camshaft provided in the crankshaft of the automobile is on, the SCR ■ is connected to the DC voltage power supply. It is an open circuit, and the output voltage of this pulse circuit is maintained at zero potential, but at the moment the point turns off, the current changes to R□
, Dl, R, , R2, R3, it creates one impulse of ■ and gives it to the SCR gate to trigger it, instantly injecting the stored power of capacitor C1 into the primary side of the ignition coil. The discharge causes a strong spark voltage to be generated on the secondary side, which ignites the spark plug.

According to such a conventional device, at the moment when the SCR is conducting, the output side of the rectifying section (■) is short-circuited, the oscillation of the high-frequency generating section (■) is stopped for that time, and the oscillation is restarted at the same time as the discharge ends, and the next SC
It has the advantage that there is no commutation failure in R, and that the engine can be driven with a spark of almost constant electric power no matter how high the rotation speed is from the start.

However, since an SCR is used to control charging and discharging of the power storage capacitor C1, a high-frequency generator is required to charge at a timing earlier than the on-off timing of this SCR, and it also requires on-off control of the SCR. SCR from points because points are used for
This has problems such as external noise entering the gate of the device, which tends to cause false ignition.

The present invention has been developed in view of the above circumstances, and by using a new charging/discharging element, no noise is generated because no points are used, the configuration is simple, and the problems of conventional devices are solved. The object of the present invention is to provide an ignition device that can solve the problem.

The present invention will be specifically explained below with reference to Examples.

First, before explaining specific examples, we will introduce a non-linear dielectric element (
(hereinafter referred to as a dielectric element) will be explained below.

This dielectric element is made of BaTiO3-BaSnO3-based porcelain and has large spontaneous polarization and D-E hysteresis characteristics close to a square shape, so it has the property that the charge Q saturates and becomes constant above a certain applied voltage. It is something that

That is, the DE hysteresis characteristic of this element has a rectangular shape as shown by curve A in FIG. 2, which is significantly different from the hysteresis curve B (broken line) shown by the conventional high permeability ceramic capacitor.

Therefore, the relationship Q=CV no longer holds true above a predetermined voltage value Vt, and when a voltage higher than that is applied, the charging/discharging current stops flowing.

From this, for example, when connected in series with the inductance L, the current flowing through the dielectric element rapidly decreases at the predetermined voltage value Vt, so a back electromotive force (-Li) is generated in the inductance L, which causes a large pulse. voltage can be obtained.

Since the predetermined voltage value Vt in this case is largely related to the thickness of the element, it can be set to any value by appropriately adjusting this thickness.

FIG. 3 is a circuit diagram of an embodiment of the present invention device using the dielectric element, which includes a rotation detection section 6, a control signal generation section 7,
It is composed of a charge/discharge control section 8 and a high voltage generation section 9.

The rotation detection unit 6 has a magnetic sensor attached to the crankshaft of an automobile, for example, and detects the state immediately before the compression operation of the intake and exhaust system (time tA in the figure) using this magnetic sensor, and generates a detection trigger pulse V1. It is designed to output .

In the case of a four-cylinder engine, the compression operation is performed twice in one revolution of the crankshaft, so the trigger pulse V□ is generated twice at regular intervals during one revolution of the crankshaft.

The control signal generating section 7 is constituted by, for example, a monostable multi-by-break circuit, and generates a predetermined width t every time the trigger pulse V1 from the rotation detecting section 6 is applied.

A control pulse signal φ1 having a value of φ1 is output.

The charge/discharge control section 8 includes a transistor Q1, a switch SW, an automobile battery E, and the transistor Q1.
and a step-up transformer HT1 connected to the collector of the control pulse signal φ1, which generates a boosted output pulse V2 synchronous with the control pulse signal φ1.

The high voltage generating section 9 includes a dielectric element NLA charged by the output pulse V2, and an ignition coil L whose primary side is connected in series to the dielectric element NLA. The high voltage pulse Vs is applied to a spark plug (not shown).

Here, the dielectric element NLA is applied for one pulse application time t of the output pulse V2 of the charge/discharge control section 8.

It is assumed that the circuit is designed to operate in saturation within a certain period of time, and the voltage value Vt at saturation is set to several hundreds of square meters.

Therefore, when this dielectric element NLA performs a saturation operation, the high voltage pulse Vs obtained on the secondary side of the ignition coil L reaches several tens of KV.

Further, it is assumed that the control pulse φ□ is set to a width such that it rises at the time when the trigger pulse is applied and rises at the time tA during the compression operation of the intake and exhaust system of the automobile.

Next, the operation of the circuit will be explained with reference to the timing chart of FIG.

First, the ignition switch SW is turned on.

The rotation detection section 6 detects the rotation of the crankshaft and outputs a trigger pulse V1 synchronized with the state immediately before the compression operation.

In this case, during the period T1 immediately after the start, the rotation speed is low, so there is a relatively wide interval between the trigger pulses, but during the high-speed period T2, the trigger pulses have a narrow interval t2. Become.

In this way, the monostable multivibrator constituting the control signal generating section 7 is operated by the trigger pulse V1 whose interval changes according to the rotational state at the time of start and at high speed. ,
Fixed set width t.

A control pulse signal φ□ is generated, and the charge/discharge control section 8
are respectively applied to the bases of transistors Q1.

In the charging/discharging control section 8, a switching operation of the transistor Q1 is performed, and an output pulse v2, which is synchronized with the control pulse φ1 and has an increased peak value, is generated from the step-up transformer HT1.
occurs.

Next, the dielectric element NLA is charged every time the output pulse (2) arrives, and when the charging voltage reaches the set value Vt, a pulsed output VNLA is generated in which the voltage rises rapidly due to saturation operation. .

A back electromotive force is generated during the saturation operation of the dielectric element NLA, and a high voltage pulse Vs is generated on the secondary side of the ignition coil L.

This high voltage pulse Vs causes the ignition plug to ignite.

Here, since the rotation detection section 6 generates the trigger pulse V in the state immediately before the compression operation, and the output pulse V2 of the charge/discharge control section 8 is set to a width such that it falls during the compression operation. , the spark plug will surely ignite during compression operation.

Note that during low-speed rotation and high-speed rotation, the timing of the compression operation during rotation will be slightly different, but the detection timing of the rotation detector 6 and the pulse width of the control pulse signal φ1 of the control signal generator 7 There is no need to worry about erroneous ignition if it is set within the allowable error range of the compression operation.

Note that if a dielectric element having a rectangular hysteresis as described above is used, it is expected that the amount of heat generated will be large, so it is preferable to attach a heat sink to eliminate this.

According to the device of the present invention described in detail above, since a dielectric element that performs its own switching operation is used as a charging/discharging element, there is no need to provide an SCR and a point for controlling this switching as in the past, so errors caused by external noise can be avoided. No need to worry about ignition.

In addition, since a dielectric element with better charging characteristics than conventional capacitors is used, a high frequency circuit, a rectifier circuit, etc. are not required, and the structure is simple and the entire device can be made inexpensive.

Although it is difficult to improve the spark generation efficiency of the dielectric element used in this invention compared to the conventional nonlinear element/capacitor configuration, it can meet the demands for simplification and miniaturization because the number of parts is small. This has the advantage that the value of the threshold voltage Vt can be changed simply by adjusting the thickness of the element, which provides convenience at the time of design.

The present invention is not limited to the above embodiments.

For example, the rotation detecting section 6 may be constituted by a shaft encoder, and the control signal generating section 7 may be constituted by an oscillation circuit.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional ignition device, Figure 2 is a characteristic diagram of a dielectric element used in the device of the present invention, Figure 3 is a circuit diagram of an embodiment of the device of the present invention, and Figure 4 is its operation. It is a timing chart for explanation. 6... Rotation detection section, 7... Control signal generation section, 8... Charge/discharge control section, 9... High pressure generation section, NLA... ...dielectric element, Ql...
...Transistor, L...Ignition coil.

Claims (1)

[Scope of utility model registration request] a control signal generating means whose output changes according to the rotational state of the rotating body; a charging/discharging means which generates a pulsed output which changes in synchronization with the output of the control signal generating means; and a BaTiO3-
An ignition device comprising a dielectric element made of BaSnO3-based porcelain, which has large spontaneous polarization and square hysteresis characteristics, and whose charge saturates and becomes constant above a predetermined applied voltage, and an ignition coil connected in series.