JPS6137454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact ignition device, and more particularly to an ignition device that controls duty using an ignition signal generated in response to engine rotation. Here, duty is defined as follows.

Duty = Ignition coil current conduction time / Ignition period x 100 (%
) It has been known to use a capacitor to increase the duty during mid-rotation of the engine or to increase the duty during high-speed rotation, as disclosed in, for example, Japanese Patent Application Laid-Open No. 54-29392.

For example, in a non-contact ignition device known from Japanese Patent Application Laid-Open No. 51-132341, a so-called duty-up capacitor and diode are connected in parallel to the input resistance of the first stage transistor, and charging is performed when the pick-up output is in the forward direction, and when it is in the reverse direction. Furthermore, the configuration is such that the discharge occurs via a resistor placed in parallel with the diode. However, in such a configuration, the resistor connected in parallel to the diode is selected to have a relatively large value, so that the capacitor is not sufficiently discharged, especially when the engine rotates at high speeds, and this causes the pick-up coil output to decrease. This may cause malfunctions. In particular, if there are variations in the peak value of the pickup coil output, the first stage transistor may not be able to shut off even when the ignition signal is generated.
This causes malfunctions such as so-called ignition failure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned shortcomings in the prior art, and it is an object of the present invention to provide a non-contact ignition device that can provide a sufficient duty-up and is free from ignition malfunctions such as ignition failure. .

An object of the present invention is to provide a non-contact ignition device having a duty control circuit suitable for a monolithic IC.

In the present invention, an ignition timing signal generated in accordance with the rotation of the engine is applied through the base resistor of the first stage transistor of the waveform amplifier circuit, and two diodes are connected in series between the base and the ground in the direction from the ground to the base. , the capacitor is provided such that a series circuit of a base-side diode of the diodes and a capacitor is provided in parallel to the resistor.

Embodiments of the present invention will be described below with reference to the drawings.
A series circuit of a resistor 13 and a diode 20 is provided between a power source and ground to apply a bias voltage to a pickup coil 1 that generates an ignition signal in response to engine rotation. In order to apply the anode voltage of this diode 20 to the pickup coil as a bias, the anode and P of the pickup coil 1 are connected to each other.
Connect the terminals with resistor 4. Further, a diode 21 is connected in parallel with the diode 20 in a reverse polarity to protect the diode 20 from a reverse applied voltage. The Q terminal of pick-up coil 1 is connected to series resistors 5, 6, and 7.
A capacitor 3 is connected to the base of a transistor 30 in the first stage of the amplifier circuit via a capacitor 3 in parallel with the resistors 6 and 7. Further, a series circuit of capacitor 2 and resistor 8 is connected to resistor 7 in parallel. A diode 19 and two more diodes 16 and 17 are connected between the base of the transistor 30 and ground.
A series circuit consisting of the following is provided. A connection point between diodes 16 and 17 and a connection point between resistor 8 and capacitor 2 are connected. Pick up coil 1
A current is supplied to the Q terminal of the power supply via the resistor 14 from the power supply.

Constant voltage zener 22 is connected to the power supply via line 36 and resistor 12 to keep the voltage on line 36 constant regardless of variations in the power supply voltage. The collector of transistor 30 is connected to line 36 via resistor 9. The base of transistor 31 is connected to the collector of transistor 30, and a base current is supplied to resistor 31 from line 36 via resistor 9 when transistor 30 is non-conducting.
The collector of transistor 31 is likewise connected to line 36 via resistor 10. The base of the transistor 32 serving as a driver for the power transistor 33 is connected to the collector of the transistor 31, and the collector is connected to the power supply via a resistor 11. The base of the power transistor 33 is connected to the collector of the transistor 32, and the collector is connected to the power source via a switching coil 34. The high voltage generated in the secondary winding of the ignition coil 34 is supplied to the ignition plug 35 via a power distributor (not shown).

The part surrounded by a dotted line in Fig. 1 is made of a monolithic IC, and the transistors 30, 3
1 and 32 constitute an amplifier circuit that controls the power transistor 33.

First, the general operation will be explained. An output shown by V1 in FIG. ₂ is generated in the pickup coil 1. Level _V3 represents the potential of the P terminal of the pickup coil. When the pickup coil output is applied to the transistor 30 through the circuit shown in FIG.
Shown at the level of V ₂ . That is, when the output V ₁ of the pickup coil 1 is above this level V ₂ , the transistor 30 is conductive, whereas when it is below this level, the transistor 30 is non-conductive. Therefore, at points S ₁ and S ₅ the transistor 30 changes from a non-conducting state to a conducting state, and at a point S ₄ it changes from a conducting state to a non-conducting state.

Consider the period between point S ₁ and point S ₄ . During this period, the transistor 30 is on, the transistor 31 is off, and the transistor 32 is on. Therefore, the power transistor 33 is in a non-conducting state, and no primary winding current flows through the ignition coil 34. That is, the transistor 30 and the power transistor 30 are in an antiphase relationship, and the transistor 3
When 0 is non-conductive, the power transistor 33 is in a conductive state. Here, the first stage transistor 30 performs waveform shaping and amplification on the output of the pickup coil. However, it is not so important whether the first stage transistor 30 and the power transistor 33 are in phase or out of phase.

Next, consider the period between point S ₄ and point S ₅ in Figure 2 A. At point _S4 , transistor 30 becomes non-conductive, transistor 31 becomes conductive, and transistor 31 becomes non-conductive. As a result, the power transistor 33
conducts, a primary current IC flows through the ignition coil 34, and this current increases as shown in FIG. 2B. At this time, reverse charging occurs in the order of the ground, the diode 16, the capacitor 2, the resistor 6, and the pickup coil 1 due to the action of the diode 16.

Due to this phenomenon, it is possible to prevent the ignition timing from being delayed due to the charge remaining in the duty-up capacitor, and to reduce the amount of ignition timing delay. Specifically, in the conventional circuit (without the diode 16), the ignition timing was delayed by about 6 degrees when the engine speed was 4000 rpm, but by inserting the diode 16, which is a feature of the present invention,
It was confirmed that this delay could be suppressed to about 3 degrees. In addition, since the capacitor 2 is charged and forcibly discharged by reverse charging every cycle of the pick-up output, overcharging of the capacitor 2 during high-speed engine rotation and ignition failure due to variations in the peak value of the pick-up coil output can occur. Eliminates ignition malfunction/
It can be prevented.

At point _S5 , transistor 30 becomes conductive, which causes power transistor 33 to become non-conductive.
A high voltage is then induced in the secondary winding of the ignition coil 34. In this way, spark energy for ignition is created.

Next, the duty control circuit will be explained. point
Between S ₁ and point S ₂ , terminal Q of pick-up coil 1
From resistor 5, 6, capacitor 2, diode 1
7. A current flows in the circuit returning to the terminal P of the pickup 1 through the base and emitter of the transistor 30, the transistor 21, and the resistor 4, thereby making the transistor 30 conductive. This current causes charge to be stored in the capacitor 2. After passing the point _S2 , the output _V1 of the pickup coil 1 rapidly decreases. Therefore, the charges stored in the capacitor 2 are discharged via the resistors 8 and 7. If this discharge current is large, a current will flow through the diode 17, but in reality the current is small and the voltage between the terminals of the resistor 8, which is the voltage between the terminals of the diode 17, is small.
Conditions in which current flows through the diode 17 rarely occur.

The discharge current of capacitor 2 serves to reduce the base current to transistor 30, rendering transistor 30 inactive. Therefore, it serves to move level V ₂ upward in FIG. Therefore, point _S4 is advanced and the duty is increased. This increase in duty is determined by the capacitance of the capacitor 2 and the time constant of the charging/discharging circuit for the capacitor 2.

FIG. 3 is a diagram showing the size of the capacitor 2 and duty. Measurements were taken using the circuit shown in Figure 1 with capacitor 3 removed. Graph A1 shows the value of capacitor 2 set to almost zero, and A ₂ , A ₃
This capacity has been increased. As can be seen from this figure, increasing the capacitor value increases the duty at engine speeds of around 1000 rpm, but the duty decreases at high speeds of around 3000 rpm. The reason for this is that the period between S' ₁ and S' ₂ in FIG.

Capacitor 3 is provided to increase duty at high speed. Between S ₁ and S ₂ in FIG. 2A, a current flows through the circuit from the pickup coil 1 to the resistor 5, the capacitor 3, and the base and emitter of the transistor 30 to the capacitor 3. This charges the capacitor 3. Next, after passing _S2 , the pickup output voltage _V1 rapidly decreases. Therefore, the charge in the capacitor 3 is discharged via the resistors 6 and 7. This reduces the base current of transistor 30 and increases the duty. Therefore, the fourth
The characteristics will be as shown in the figure. In the present invention as described above, it is sufficient to simply add the diode 16, and in particular,
This can be easily configured in an IC circuit.

The duty of the circuit shown in FIG. 1 is a combination of the characteristics shown in FIGS. 3 and 4, and is as shown in FIG. 5.

FIG. 6 shows another embodiment of the invention, in which the same numbers as in FIG. 1 have similar functions. A diode 18 is provided in place of the temperature compensation diode 20 for the transistor 30 in FIG.

According to the present invention described above, it is possible to improve duty and prevent ignition malfunction.
Moreover, it becomes possible to provide a non-contact ignition device having a structure that is advantageous for monolithic construction.

[Brief explanation of the drawing]

Fig. 1 is an embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation, Fig. 3 is a characteristic diagram showing the relationship between the capacitor 2 in Fig. 1 and the duty size, and Fig. 4 is the capacitor shown in Fig. 1. A characteristic diagram showing the relationship between 3 and duty,
FIG. 5 is a characteristic diagram of FIG. 1, and FIG. 6 is another embodiment of FIG. 1. 1... Pickup coil, 2, 3... Capacitor, 22... Zener diode, 33... Power transistor, 34... Ignition coil, 35...
...Spark plug.

Claims (1)

[Claims] 1. An ignition signal is generated by a pickup coil in accordance with the rotation of the engine, the ignition signal is applied to an amplifier circuit via a resistor, a power transistor is controlled by the amplifier circuit, and a power transistor is controlled by the power transistor. In a device that induces a high voltage by controlling the ignition coil current, a series circuit having a first diode and a capacitor is connected to the resistor in such a manner that the cathode of the first diode is on the input side of the amplifier circuit. A second diode is provided between the anode of the first diode and the ground in such a direction that the anode side becomes the cathode and the space between the grounds becomes the anode, and further the amplifier circuit and the first and second diodes are monolithically connected. A non-contact ignition device characterized by being composed of an IC. 2. The non-contact ignition device according to claim 1, further comprising a second capacitor provided in parallel with the resistor.