JPS62355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact ignition device for an internal combustion engine, and an object of the present invention is to be able to set the ignition timing without adjustment and to obtain a significant advance angle operation.

BACKGROUND OF THE INVENTION As the reliability of semiconductor switching elements has improved, contactless ignition devices for internal combustion engines have come to be used in large quantities and in many fields.

This non-contact ignition device has the advantages of being lightweight, compact, and long-lasting, but on the other hand, in order to match the internal combustion engine to which it is installed, it requires various settings, mainly the ignition timing, for each internal combustion engine. It was necessary to carry out a setting process, and the assembly required specialized skills.

Furthermore, as is well known, in order to effectively extract the output of an internal combustion engine, it is well known that it is necessary to advance the ignition timing at high speeds compared to at low speeds.

There are various means for advancing the ignition timing, but from the viewpoint of function and structure, it is desirable to achieve this electrically, and various methods have been proposed in accordance with this desire.

The common features of the advance means in conventional non-contact ignition systems are that the circuit configuration is complicated, the advance width is small and it is not possible to obtain a sufficient advance effect, and there are differences depending on the individual machine to which it is installed. Since the amount of advance angle differs, there are inconveniences such as having to set and adjust the amount of advance angle for each individual machine, and this is by no means satisfactory.

The present invention was devised to eliminate the drawbacks and dissatisfied points of the conventional example described above, and utilizes the impedance change with respect to the frequency of the capacitor to change the triggering method of the silicon-controlled rectifier that sets the ignition timing at low speed and high speed. This change is configured to significantly advance the ignition timing at high speeds.

An embodiment of the present invention will be described below with reference to the drawings.

The non-contact ignition device for an internal combustion engine according to the present invention includes:
A _first resistor _R1 having a high resistance value, a transistor _Tr , a first capacitor _C1 and a series circuit, a transistor circuit TrC (in the illustrated embodiment, this transistor circuit is a Darlington circuit, but depending on the case, it may be a single power transistor), and a second resistor with a resistor value. series circuit with resistor R ₂ and
Silicon controlled rectifier with a high resistance third resistor _R3 and a gate resistor _R5 inserted between the gate and cathode
A series circuit with an SCR (hereinafter simply referred to as a thyristor) is inserted in parallel, the base of the transistor Tr is connected to the emitter connected to the resistor _R2 of the transistor circuit TrC, and the base of the transistor TrC is connected to the emitter connected to the resistor _R1 . The collector of the transistor Tr is connected to the gate of the thyristor SCR, the base of the transistor circuit TrC is connected to the anode of the thyristor SCR connected to the resistor _R3 , and a transistor Tr is connected between the anode and the gate of the thyristor SCR. It is constructed by inserting a series circuit of a capacitor C ₂ and a resistor R ₆ .

In the illustrated embodiment, a resistor is connected between the emitter of the transistor Tr and the base of the transistor circuit TrC.
A series circuit of R ₈ and diode D ₁ in the opposite direction is inserted, and a transistor circuit is inserted.
A Zener diode ZD in a reverse orientation is inserted between the base and collector of the TrC, forming a pre-spark prevention circuit and a charging circuit for reverse voltage to the first capacitor _C1 . .

In addition, a resistor _R4 is connected to the line connecting the collector of the transistor Tr and the gate of the thyristor SCR.
is inserted to ensure stable triggering of the thyristor SCR.

Furthermore, a series circuit consisting of a thermistor Th, a resistor R ₇ , and a diode D ₃ is inserted between the electrode of the second capacitor C ₂ connected to the resistor R ₆ and the cathode of the thyristor SCR. , forming a temperature compensation circuit for the gate of the thyristor SCR.

Note that the diode D ₂ in the reverse direction inserted between the gate and cathode of the thyristor SCR is to form a circuit for charging the second capacitor C ₂ with a reverse voltage, but the gate resistance
It may be omitted depending on the value of _R5 .

The ignition device according to the present invention has the above-described configuration, and the operation of the present invention described above will be explained in order.

When the flywheel (not shown) rotates, the magnetic force of the permanent magnet embedded in the flywheel causes the primary winding of the ignition coil T to
A voltage is induced at T ₁ .

Regarding the voltage induced in the primary winding _T1 , a reverse voltage is induced before a forward voltage.

At low speeds, including when starting an internal combustion engine, the reverse voltage induced in the primary winding _T1 prior to the forward voltage charges the first capacitor _C1 with a reverse voltage with the polarity shown. Primary winding T ₁ →
Resistor R ₅ or diode D ₂ → Resistor R ₆ → Second capacitor C ₂ → Zener diode ZD or resistor
The second capacitor C ₂ is also charged with a reverse voltage along the path from R ₃ to the primary winding T ₁ .

The reverse voltage charged on the first capacitor _C1 is
Before the induced voltage in the primary winding T ₁ is reversed in the forward direction, the first capacitor C ₁ → resistor R ₁
→ Base of transistor Tr → Emitter of transistor Tr → First capacitor C ₁ It is discharged along the path, and the transistor Tr is triggered by this discharge.

On the other hand, the reverse voltage charged in the second capacitor C ₂ is caused by the second capacitor C ₂ → resistor R ₆ → resistor R ₅ →
Primary winding T ₁ → resistor R ₃ → second capacitor C ₂ , or second capacitor C ₂ → resistor R ₆ → resistor R ₅ → resistor R ₂ → transistor circuit TrC → resistor R ₃ → second capacitor It is discharged through a path such as C ₂ .

Due to this discharge of the second capacitor _C2 , the potential at point A, which is the anode of thyristor SCR, is held at a lower value than the potential at point B, which is the gate of thyristor SCR.

When a forward voltage is induced in the primary winding T ₁ from this state, a current flows through the resistor R ₃ to the base of the transistor circuit TrC according to the forward voltage induced in the primary winding T ₁ . flows in, the transistor circuit TrC is turned on, and by turning on the transistor circuit TrC, a primary short-circuit current I ₁ flows through the transistor circuit TrC to the primary winding T ₁ .

When the primary short-circuit current _I1 flows through the transistor circuit TrC, a voltage drop occurs between both terminals of the resistor _R2 , and a portion of the primary short-circuit current _I1 flows from the base of the transistor Tr to the emitter. , and charges the first capacitor C ₁ with the opposite polarity to that shown.

As the forward voltage in this first capacitor _C1 progresses, the base current of the transistor Tr does not increase even though the value of the primary short-circuit current _I1 increases.
The collector potential of the Tr increases, and this increased potential is applied to the gate of the thyristor SCR.

The collector potential of the transistor Tr applied to the gate of this thyristor SCR is
Even if the trigger level of the SCR is reached, due to the discharging operation of the second capacitor _C2 , the thyristor
Thyristor SCR
cannot be turned on.

That is, as is clear from Fig. 2 a and b, 1
Even if the next short-circuit current _I1 becomes sufficiently large, the _thyristor
The rising speed of the SCR anode-gate voltage V _GB is delayed, and the thyristor SCR turns on at time t ₁ , which is much later than the time when the primary short-circuit current I ₁ reaches its maximum. The circuit TrC turns off to cut off the primary short-circuit current _I1 , induces a high voltage in the secondary winding _T2 , and generates a spark discharge in the plug P, thereby performing an ignition operation.

Similarly, at this low speed, the second capacitor
The V _c between both electrodes of C ₂ is as shown in Figure 3b, and the second
The voltage V in Figure b changes almost the same as _GB .

When the engine speed increases from this state to normal operating speed, the discharge operation of the first capacitor _C1 and the second capacitor _C2 is performed in exactly the same way as at low speed, but the engine speed increases. As the rotational speed increases, the frequency of the voltage induced in the primary winding _T1 increases.

Also, as the engine speed increases, the primary winding
The rising speed of the forward voltage at _T1 also increases, and the collector potential of the transistor Tr also rises faster.

Therefore, the voltage applied to the gate of the thyristor SCR quickly reaches a large value, and the voltage applied to the gate of the thyristor SCR quickly reaches a large value.
Due to the frequency-dependent impedance characteristics of the capacitor C ₂ , the primary short-circuit current I ₁ passing through the resistor R ₃
A part of the current flows directly through the second capacitor _C2 and into the gate of the thyristor SCR via the resistor _R6 , so the gate potential of the thyristor SCR rises quickly and the second capacitor _C2 is charged. Thyristor despite discharge of reverse voltage
The potential difference between the anode and gate of the SCR, ie, the voltage _VGB, reaches a value that can trigger the thyristor SCR.

That is, as shown in FIG. 2c and b, the primary short-circuit current _I1 is cut off at time t2, which is much earlier than time _t1 , and at this time _t2 , the voltage V between _the anode and gate of thyristor SCR Thanks to the increased frequency, _GB has reached a value at which the thyristor SCR can be triggered by a portion of the primary short-circuit current I ₁ passing through the second capacitor C ₂ .

On the other hand, as is clear from Fig. 3c and d, at the time _t2 when the primary short-circuit current _I1 is cut off, the reverse voltage charged in the second capacitor _C2 has not yet been completely discharged. It turns out there isn't.

In this way, even though the reverse voltage of the second capacitor _C2 has not been completely discharged, the voltage between the anode and gate of the thyristor _SCR
The value that can trigger is that the amount of voltage drop across resistor _R6 due to a portion of _the primary short-circuit current _I1 passing through the second capacitor C2 due to an increase in frequency This is because it is much larger than the reverse voltage remaining at ₂ .

In this way, the second capacitor C ₂ inserted between the anode and gate of the thyristor SCR is effective against this primary short circuit current I ₁ at low speeds, that is, when the frequency of the primary short circuit current I ₁ is low. By exhibiting high impedance, the anode of thyristor SCR
By delaying the rise of the gate voltage V _GB and setting the ignition point at a delayed time t ₁ , as the engine speed increases and the frequency of the primary short-circuit current I ₁ increases,
It provides a low impedance to this primary short-circuit current I ₁ and allows a portion of this primary short-circuit current I ₁ to flow directly into the gate of the thyristor SCR, thus causing the thyristor SCR to trigger at an earlier time t ₂ . It acts on

For this reason, the ignition timing when the engine is running at high speed is significantly advanced compared to when the engine is running at low speed, making it possible to obtain extremely good ignition operation.

Furthermore, since the basis of the ignition operation of the present invention is the operation of increasing the potential of the collector of the transistor Tr by the action of the first capacitor _C1 , there is no need to adjust the setting of the ignition timing at all.

As is clear from the above description, the ignition system according to the present invention does not require any setting adjustment of the ignition timing when installed on the engine, and can significantly advance the ignition timing as the engine speed increases. As a result, it is possible to obtain good engine operation, and it has many excellent effects such as a simple circuit configuration.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing one embodiment of the present invention. Figure 2 shows the changes in the primary short-circuit current and the current between the anode and gate of the thyristor.
Figure a is a primary short-circuit current waveform diagram at low speed, and Figure 2 b is the thyristor anode and waveform diagram at low speed.
FIG. 2c is a waveform diagram of the primary short-circuit current at high speed, and FIG. 2d is a waveform diagram of the voltage between the anode and gate of the thyristor at high speed. Figure 3 shows the changes in the primary short-circuit current and the voltage between the two electrodes of the second capacitor. Figure 3a is a waveform diagram of the primary short-circuit current at low speeds, and Figure 3b is a waveform diagram of the primary short-circuit current at low speeds. FIG. 3c is a waveform diagram of the voltage between the electrodes. FIG. 3c is a waveform diagram of the primary short circuit current at high speed. FIG. 3d is a waveform diagram of the voltage between the capacitor electrodes at high speed. Explanation of symbols, T...Ignition coil, T ₁
...Primary winding, _T2 ...Secondary winding, P...Plug, Tr...Transistor, TrC...Transistor circuit, _R1 , _R2 , _R3 , _R4 , _R5 , _R6 , _R7 , _R8 ...
Resistance, C ₁ , C ₂ ... Capacitor, D ₁ , D ₂ , D ₃ ...
Diode, ZD... Zener diode, Th...
...thermistor, I ₁ ... primary short circuit current, V _GB ... voltage between the anode and gate of the thyristor, V _c ... voltage between both electrodes of the second capacitor, t ₁ , t ₂ ... time.

Claims (1)

[Claims] 1 Between both terminals of the primary winding of the ignition coil with a plug connected to the secondary winding, there is a series circuit of a first resistor with a high resistance value, a transistor, and a first capacitor, and a series circuit of a transistor circuit and a low resistance. The base of the transistor is the emitter of a transistor circuit connected to the second resistor, the collector of the transistor connected to the gate of the silicon controlled rectifier, the base of the transistor circuit connected to the anode of the silicon controlled rectifier; Silicon controlled rectifier anode
An ignition device consisting of a series circuit of a second capacitor and a resistor inserted between the gates.