JPS6137461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction discharge type non-contact ignition device for an internal combustion engine, and more specifically, the present invention relates to an inductive discharge type non-contact ignition device for an internal combustion engine. The purpose is to ensure a retardation of the ignition timing at low speeds, including during startup.

An internal combustion engine uses an external force to rotate the crankshaft in a certain direction, which then activates the ignition device to start the engine, but the external force that acts to drive the internal combustion engine is generally weak. Since the rotational speed of the crankshaft rotated by this external force is also slow, the inertia of the moving parts of the internal combustion engine is extremely small, and as a result, the ignition timing at startup is close to the top dead center of the compression process. It needed to be set to .

In other words, if the ignition timing is far advanced from the point at which the compression process is completed, as mentioned above, the inertia of the moving parts of the internal combustion engine at the time of startup is small, making it difficult to overcome the explosive force of the fuel gas. The crankshaft cannot be rotated in the normal direction to complete the compression process, and the crankshaft will rotate in the opposite direction, resulting in a butt.

In this way, the ignition system of an internal combustion engine is set to a position where the ignition timing at the time of starting is sufficiently retarded, but in the case of an internal combustion engine that is started by input using a starting rope or lever, The force that rotates the crankshaft to start the engine,
In other words, due to weak human power, large variations occur in the rotational speed of the crankshaft during startup.

For example, when the piston is in the suction stroke, the resistance to the crankshaft's rotational movement is small, so the crankshaft can be rotated at a relatively fast speed, but when the piston enters the compression stroke, the compression stroke slows down. The further the engine advances, the greater the resistance force acting on rotating the crankshaft, resulting in a significant reduction in the rotational speed of the crankshaft.

Particularly, in a large engine with a high horsepower such as a four-cycle engine, the above-mentioned unevenness in the rotational speed of the crankshaft at the time of startup inevitably occurs.

In this way, if there is a large unevenness in the rotational speed of the crankshaft during startup, and the rotational speed of the crankshaft during the engine compression process becomes slower than at other times, the normal settings will be changed to compensate for this slowdown. The ignition operation is performed at a position before the rotation position.

In other words, the ignition timing is advanced by the amount that the rotational speed of the crankshaft is reduced.

In this way, if the ignition timing is advanced during startup, the explosive force of the fuel gas will cause the crankshaft to rotate in the opposite direction to the direction that the human power is trying to rotate it. .

The ass that is generated when starting this engine is
Not only does this have a negative mechanical effect on the engine, but above all it poses a serious danger to the engine operator, and there has been a strong desire to prevent this occurrence as much as possible.

The present invention was devised in response to the above-mentioned conventional aspirations, and uses a capacitor to absorb the voltage that acts on the ignition operation that occurs at a point advanced from the set normal time at low speeds including starting. It is designed to prevent ignition operation at a position where the angle is improperly advanced.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
A first resistor R1 having a high resistance value, a transistor _Tr , and a first capacitor are connected between both _terminals of a primary winding _T1 of an ignition coil T having a secondary winding T2 connected to a spark plug P. Series circuit with C ₁ ,
A series circuit of a transistor circuit TrC in which two transistors are connected in Darlington (this transistor circuit TrC may be one power transistor), a second resistor R2 with a low resistance value, and a third resistor _R2 with a high resistance value. Resistor R ₃ and silicon controlled rectifier SCR
(hereinafter simply referred to as thyristor SCR) is inserted in parallel, the base of the transistor Tr is connected to the emitter connected to the second resistor _R2 of the transistor circuit TrC, and the The collector connected to one resistor _R1 is connected to the gate of a thyristor SCR in which a gate resistor _R4 is inserted between the gate and cathode, and the base of the transistor circuit TrC is connected to a thyristor connected to a third resistor _R3 . The ignition circuit is configured by inserting a second capacitor _C2 between the emitter of the transistor circuit TrC connected to the anode of the SCR and the gate of the thyristor SCR.

The ignition circuit according to the invention is constructed as described above, but in the illustrated embodiment, the gate of the thyristor SCR is connected to the cathode in parallel with the second resistor _R2 , that is, via the second capacitor _C2 . A thermistor Th is connected in this manner, and a diode _D1 in a reverse orientation is connected in parallel with the gate circuit _R4 .

The thermistor Th inserted between point A, which is the emitter of the transistor circuit TrC, and point B, which is the negative terminal of the primary winding _T1 when forward voltage is generated, is connected to the thermistor Th when the internal combustion engine operates. Thyristor due to increase in ambient temperature of igniter
As the gate sensitivity of the SCR becomes more sensitive, that is, the trigger voltage of the thyristor SCR decreases, the potential at point A is controlled by decreasing the resistance value of the thermistor Th as the temperature rises, and the overall circuit It performs temperature compensation control.

Also, the diode D ₁ is connected to the second capacitor C ₂
This diode D1 forms a discharge circuit, but this diode _D1 may be provided as necessary.

Note that the resistor inserted between the emitter of transistor Th and the base of transistor circuit TrC
The series circuit between R ₅ and the diode D ₂ in the reverse direction is for preventing premature ignition, and the Zener diode ZD in the reverse direction inserted between the base and collector of the transistor circuit TrC prevents premature ignition. In addition to acting to prevent ignition, the transistor circuit TrC
This protects the device from surge voltage.

Since the ignition device according to the present invention has the circuit configuration as described above, when the flywheel (not shown) rotates by turning the crankshaft, the primary winding T ₁
A forward voltage rises, and this forward voltage causes a base current to flow from the third resistor _R3 to the base of the transistor circuit TrC.
turns on, causing the primary short-circuit current to flow through the primary winding _T1 .

On the other hand, prior to the rise of the forward voltage in the primary winding T ₁ , a reverse voltage is induced in the primary winding T ₁ , and this reverse voltage is charged in the first capacitor C _1. The electric charge charged in this first capacitor _C1 is transferred to the first capacitor C1.
C ₁ → second resistor R ₂ → base of transistor Tr →
Emitter of transistor Tr → first capacitor
Because it is discharged in the path of _C1 , the transistor
Tr is in the triggered state, so that at the same time as the primary short-circuit current flows, the transistor Tr turns on and the first capacitor C ₁ charges the forward voltage.

When the primary short-circuit current increases, the potential at point A, ie, the base potential of the transistor Tr, increases, but similarly, the potential at the plus side electrode of the first capacitor _C1 , ie, the emitter potential of the transistor Tr also increases.

The base potential of the transistor Tr changes according to the change in the primary short-circuit current, whereas the emitter potential of the transistor Tr changes according to the change in the primary short-circuit current.
As long as the transistor Tr is turned on, it only increases and does not decrease. Therefore, when the primary short-circuit current reaches near its maximum value, the potential difference between the base and emitter of the transistor Tr is sufficient to maintain the conduction of the transistor Tr. Therefore, the transistor Tr is turned off.

When the transistor Tr is turned off, the collector potential of the transistor Tr suddenly rises, and this rapidly rising collector potential causes the thyristor to turn off.
Applied to the gate of SCR to trigger thyristor SCR and make it conductive.

Due to the conduction of the thyristor SCR, the base of the transistor circuit TrC becomes a low potential, so the transistor circuit TrC is turned off, and the primary short-circuit current is suddenly cut off, inducing a high voltage in the secondary winding _T2 . Then, a spark discharge is generated in the plug P, and an ignition operation is performed.

The ignition device according to the present invention performs the basic ignition operation as described above, but at low speeds including starting, the reverse voltage charged in the first capacitor _C1 is small or almost non-existent. Therefore, the transistor circuit TrC turns on and the primary short circuit current starts flowing.
The point at which Tr turns on will be significantly delayed.

This delay in turn-on of the transistor Tr does not itself cause any problem in normal ignition operation, but because the transistor Tr is in a cut-off state even though the primary short-circuit current is flowing. , the collector potential of the transistor Tr rises rapidly at the beginning of the conduction period of the primary short-circuit current, and sometimes this rapidly rising collector potential reaches the trigger level of the thyristor SCR, triggering the thyristor SCR and performing an ignition operation. There are cases.

In other words, the transistor Tr turns on,
Long before the normal ignition operation achieved by turning off this transistor Tr,
In other words, the ignition operation is performed at a far advanced position, and this advancement of the ignition timing at low speeds, including during start-up, causes a sagging phenomenon.

However, in the case of the present invention, the thyristor
Since a second capacitor _C2 is inserted between the gate of SCR and the emitter of transistor circuit TrC, the collector voltage that rises before turning on transistor Tr and is applied to the gate of thyristor SCR is It is absorbed by the capacitor _C2 of 2, and the gate potential of the thyristor SCR cannot be raised.

That is, the second capacitor _C2 forms a kind of integration circuit in combination with the first resistor _R1 , thereby preventing a rapid rise in the gate potential of the thyristor SCR.

As described above, the ignition device according to the present invention can reliably prevent unnecessary advancement of the ignition timing at low speeds including the time of starting, and can reliably prevent the occurrence of the sagging phenomenon.

By the way, the basic ignition operation of the ignition device according to the present invention is that the collector voltage that rises when the transistor Tr is turned off is activated by the thyristor.
As explained above, this is achieved by applying a voltage to the gate of the SCR, but as the rotational speed of the internal combustion engine increases, the value of the first resistor R ₁ increases prior to the ignition timing due to the ignition operation described above. Therefore, the emitter of transistor circuit TrC → transistor Tr
A gate current flows into the gate circuit of the thyristor SCR through the path from the base of the transistor Tr to the collector of the transistor Tr and the gate of the thyristor SCR, and this current performs the ignition operation.

For this reason, the ignition device advances the ignition timing as the rotational speed of the engine increases.

If the engine rotational speed is further increased to make it faster, the voltage induced in the primary winding T ₁ will become a high-frequency AC voltage, and along with this, the current flowing through the primary winding T ₁ will also become AC-like. It will strengthen your character.

In this way, when the alternating current character of the current flowing through the primary winding _T1 becomes stronger, the impedance of the second capacitor _C2 becomes a small value according to the formula 1/2πfc. The result is that the potential is applied directly to the gate of the thyristor SCR.

In other words, the second capacitor _C2 acts as a high-pass filter when the engine speeds up, so that the potential at point A, that is, the emitter of the transistor circuit TrC, is lower than that of the thyristor SCR.
When the trigger potential of the gate is reached, the ignition operation will be performed, and the ignition device will further advance the ignition timing.

In short, the second capacitor C ₂ acts to further retard the ignition timing when the engine is running at low speeds, including when starting, and acts to advance the ignition timing when the engine is running at high speeds. The engine thus operates very efficiently over the entire speed range.

As is clear from the above description, the ignition device according to the present invention reliably maintains the retardation of the ignition timing at low speeds including the time of starting, and can completely prevent the occurrence of sagging, thereby improving operation. The engine can be started and operated with peace of mind, completely eliminating danger to people.
In addition, the ignition timing can be greatly advanced at high speeds, allowing the engine to run more efficiently.Furthermore, the circuit configuration is simple, making it easy to manufacture and inexpensive. It has action and effect.

[Brief explanation of the drawing]

The drawing is an electrical connection diagram showing an embodiment of the present invention. Explanation of symbols, T...Ignition coil, T ₁
...Primary winding, _T2 ...Secondary winding, P...Plug, TrC...Transistor circuit, Tr...Transistor, SCR...Silicon controlled rectifier, _C1 ,
C ₂ ... Capacitor, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ ... Resistor, D ₁ , D ₂ ... Diode, ZD ... Zener diode, Th ... Thermistor.

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. A series circuit with a second resistor of a high resistance value and a series circuit of a third resistor with a high resistance value and a silicon-controlled rectifier having a gate resistor inserted between the gate and cathode are connected in parallel, and the base of the transistor is connected in parallel. is connected to the emitter of the transistor circuit, the collector of the transistor is connected to the gate of the silicon-controlled rectifier, the base of the transistor circuit is connected to the anode of the silicon-controlled rectifier, and the emitter of the transistor circuit and the silicon control A non-contact ignition device for an internal combustion engine comprising a second capacitor inserted between a rectifying element and a gate.