JPS5925114B2 - internal combustion engine ignition system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine ignition device that generates an ignition voltage by intermittently controlling the primary current of an ignition coil by a switch circuit activated by an ignition signal. In general, this type of current interrupting type ignition device generates an ignition voltage. In an ignition system, the ignition energy depends on the primary cut-off current value of the ignition coil, and this primary current gradually increases depending on the time constant of the power supply circuit, so the ignition energy must be set at a predetermined value in order to secure the required ignition energy. In order to obtain a breaking current value of , at least a predetermined energization time is required.

In determining this energization time, since the primary current cutoff timing is the ignition timing, it is necessary to determine the primary current cutoff time based on this ignition timing. If the cut-off time is determined to be short in order to obtain sufficient energization time when the ignition interval is short, the energization time will be longer than necessary at low speeds where the ignition interval is long, increasing the power loss of the device, or causing overcurrent. may damage equipment components.

In this invention, the charging or discharging time is controlled by controlling the transistor of the capacitor charging or discharging circuit provided to determine the intermittent time of the primary current of the ignition coil by the generated voltage of the ignition signal generator. It is possible to control the primary current energization time to a desired value by controlling the secondary current cutoff time according to the engine speed, and also to prevent the device from occurring when power supply voltage fluctuations (ripples) occur due to the use of the above-mentioned capacitor. It is an object of the present invention to provide an internal combustion engine ignition device that can prevent malfunctions and also enable reliable ignition operation even when starting the engine, thereby improving starting performance.

An embodiment of the present invention shown in the drawings will be described below.

That is, first, in FIG. 1, 1 is a battery, 2 is a key switch, 3 is a signal generator consisting of a magnet generator driven by the engine, and 4 and 5, together with a diode 6, are connected in accordance with the output voltage of the signal generator 3. Resistors 7 and 8 provide a bias, and diodes 7 and 8 constitute a positive and negative current path for the output voltage, and 10.11 constitutes a Schmitt circuit together with resistors 12, 13, 14, and 15, and the output voltage of the signal generator 3 is 16 is a transistor that opens and closes in the same phase as the transistor 11 in the latter stage of the Schmitt circuit, 17 and 18 are its base resistance and collector resistance, and 19 is charged in synchronization with the opening and closing of the transistor 16. A capacitor that starts discharging, 20 is a transistor provided in the discharge (reverse charge) circuit of this capacitor,
21 is a resistor connected to the discharge circuit to form an emitter follower circuit for this transistor, 22゜23
are a resistor and a diode connected in series with each other; 24 is a transistor that receives the collector potential of the transistor 11 through the resistor 22 and diode 23; and receives the potential at one end of the capacitor 19 through a diode 25; 26 is a collector resistor thereof; , 27.28 are the transistors 24
29, 30, and 31 are resistors, and 32 is a Darlington connection type transistor. The driving switch circuit constituted by these transistor resistors opens and closes in accordance with the potential of the terminal of the transistor 24 side of the capacitor 19. .

33 is an ignition coil to which the primary current is turned on and off by the transistor 32;

34 is an engine spark plug connected to the secondary side of this ignition coil, 35 and 36 are resistors that divide the output voltage of the signal generator 3, and 37 is a voltage that is connected to the output voltage of the signal generator 3 through a diode 38. The charging voltage of this capacitor is applied to the base of the transistor 20, and its emitter potential is regulated to the charging voltage.

Next, the operation of this embodiment will be explained.

When the key switch 2 is turned on and the engine is started, the signal generator 3 generates a positive and negative alternating voltage as shown in FIG. The transistor 11.16 is closed, and the transistor 11.16 is opened. Conversely, when the voltage is below the predetermined level (including the negative electrode), the transistor 10 is opened and the transistor 11.16 is closed.

Now, at time t in FIG. 2, if the positive electrode voltage of the signal generator 3 exceeds a predetermined level and the transistor 10 is closed and the transistors 11 and 16 are opened, the capacitor 19 is connected to the resistor 1.
8, and the potential at its positive terminal, that is, point C, increases as shown in FIG. The charging current of the capacitor 19 and the current passing through the resistor 22 are applied to the base of the transistor 24, the transistor 24 is closed, the transistors 27 and 18 are open, and the transistor 32 is closed, and the primary current is supplied to the ignition coil 33. has been done.

On the other hand, the positive electrode voltage of the signal generator 3 charges the smoothing capacitor 37, and this charging voltage corresponds to the engine speed, and the transistor 20 exhibits a degree of conductivity that should regulate the emitter potential at the charging voltage. At t2, when the positive electrode voltage of the signal generator 3 falls below a predetermined level, the transistor 10 is opened and the transistor It, 16 is closed and turned on. potential).

The voltage at the transistor 24 side terminal of this capacitor 19, that is, the voltage at point d, is lowered to a negative potential by the positive amount of the charge at that time, as shown in FIG. , as well as the resistor 22 and the diode 23, the base current of the transistor 24 is cut off and the transistor 2
4 is open, transistors 27 and 28 are closed, and transistor 32 is open, and 1 of the ignition coil 33 is closed.
Next, the current is cut off as shown in FIG. 2f, and the potential at point g increases rapidly as shown in FIG.

At time t2 (ignition timing), the potential at point d, which has been lowered by the charge on capacitor 19, gradually increases as shown in FIG. , when this potential reaches a value that can close the transistor 24 at time t3, the current flowing through the transistor 20 and the resistor 21 flows through the diode 25 to the base of the transistor 24, which closes the ignition coil 33. Power supply starts.

After that, at time t4, the positive voltage of the signal generator 3 again closes the transistor 10, and the transistors 11 and 1
6 is opened, the capacitor 19 is charged to the illustrated polarity as explained at time t1, and then at time t5, when the transistor 10. Flowers are what emerges.

That is, the primary current cutoff time of the ignition coil 330 is determined by the reverse charging period of the capacitor 19 until the potential at point d reaches a predetermined level, and this cutoff time is determined by the ignition interval (
The time subtracted from the period) becomes the primary current energization time.

Capacitor 1 for determining the primary current cutoff time
9 is reversely charged toward the emitter potential (steady potential) of the transistor 20 with the time constant of the capacitor 19 and the resistor 21, and the emitter potential is the smoothing capacitor 37 charged with the output voltage of the signal generator 3 as described above. Since the base potential is regulated by the base potential given by the engine, it increases as the engine speed increases, and therefore, the time when the potential at point d reaches a level that can open the transistor 24 is when the engine is running at high speed, as shown in FIG. As t′→(/, tm.

The primary current cutoff time becomes shorter.

This means that the closing angle of the transistor 32 increases as the engine speed increases. Therefore, even if the closing angle at low engine speeds is set small, a sufficient breaking current can be obtained even at high speeds.

In this circuit, the charging time constant (depending on the values of the resistor 18 and capacitor 19) of the circuit that charges the capacitor 19 to the indicated polarity is set to a large value, so that the charging time constant (depending on the values of the resistor 18 and the capacitor 19) of the circuit that charges the capacitor 19 to the indicated polarity is changed by changing the charging time due to the change in engine speed. By changing the pressure, the initial voltage of the above-mentioned reverse charge (discharge) changes depending on the rotation speed, so effective control is performed to shorten the primary current cutoff time at high speeds. .

By the way, what is more important in this circuit is that a circuit including a resistor 22, a diode 23, and 25 is provided to provide the terminal potential output of the capacitor 19 and the switching output of the transistor 11 in parallel addition to the base of the transistor 240. This prevents the device from malfunctioning due to power ripple.

That is, various electrical loads (not shown in the figure) are connected to the battery 1, and when the load switch is turned on, the terminal potential of the battery 1 may drop momentarily, or the connection of the battery 1 may drop momentarily. When the charging generator is disconnected and the charging generator becomes the power source, there is a large power ripple.

If the power supply voltage drops even momentarily due to this power supply ripple while the transistors 11 and 16 are open, the capacitor 19 will be charged to the polarity shown in the figure during this period, and this charging voltage will be greater than the reduced power supply voltage. At this time, the potential at point d becomes a negative potential, and the base current of the transistor 24, which has been applied through this point d, is cut off, but the collector output of the transistor 11 is transferred to the resistor 22 and the diode 23.
The base current of the transistor 24 continues to flow through the transistor 24 to maintain the closed circuit of the transistor 24.

At this time, the diode 25 prevents the base current passing through the resistor 22 from being drawn toward the point d, where the potential has dropped to a negative potential.

Therefore, when the power supply fluctuates, the charge on the capacitor 19 increases! Therefore, even if the potential at point d becomes negative, the transistor 24 is opened and the primary current of the ignition coil 33 is cut off, preventing erroneous ignition. Reliable ignition operation is performed at the appropriate time.

Also, the capacitor 19 is connected to the base of the transistor 24.
In addition to the terminal potential output of the transistor 11, the opening/closing output of the transistor 11 is given in parallel.
Even when all the circuits are biased to the open circuit state, the desired closed circuit ratio can be ensured at low speeds such as when starting the engine, and reliable ignition can be achieved.

That is, in order to cut off the power supply to the ignition coil 3 when the key switch 2 is turned on when there is no signal when the engine is stopped, the unstable time of this type of monostable circuit (the discharge time of the capacitor 19) must be output. In the type of device that determines the opening time of the transistor 32, special means is required to place the monostable circuit in a state in which it generates an output similar to an unstable state rather than a stable state when there is no signal. As in the case where the discharge circuit of the capacitor 19 is provided with a transistor 20 for controlling the discharge time, if this transistor 20 is set to an open state when there is no signal, the base current of the transistor 24 is cut off, similar to an unstable output. output state.

By the way, in this case, it is necessary to set the voltage level of the capacitor 37 when there is no signal to a low level that does not allow the transistor 20 to operate, and on the other hand, in order to enable ignition at the time of starting the aircraft, When the signal voltage is low and the signal period is unstable, it is necessary to set the smoothed voltage level of the capacitor 37 to a voltage level that operates the transistor 20 in order to provide the appropriate closing rate at that time. The setting is extremely difficult, and it is difficult to maintain the output transistor 32 in an open state when there is no signal to stop the engine, and at the same time to secure a desired closed circuit ratio and ensure engine starting performance when the engine is started.

Therefore, the output transistor 32 can be reliably opened and closed by opening and closing the output transistor 32 in situations where it is difficult to control the N closing rate, such as when starting the machine, by the output of the switch circuit that responds to the voltage level of the signal generator 3. Therefore, reliable ignition can be achieved at a desired closing rate at low speeds such as during aircraft start-up.

Therefore, according to the present device, the output transistor 32 is determined by the output of the larger closing rate among the closing rate determined by the terminal potential of the capacitor 19 constituting the monostable circuit and the output of the transistor 11 of the switch circuit.
Since the opening and closing are controlled, when the monostable circuit's closing rate does not reach the desired value, such as when starting the machine, the output of the switch circuit enables reliable ignition, and the monostable circuit provides sufficient closing rate control. Once the operating state is reached, the output transistor 32 can be controlled to open and close at the controlled closing rate.

Note that the transistor 16 does not necessarily need to be provided, and in this case, the capacitor 19 can be connected to the collector terminal of the transistor 11 to achieve the same effect as described above.

As described above, the present invention provides a first
The capacitor is charged and discharged by the switch circuit of the capacitor, and the transistor of the charging or discharging circuit of the capacitor is controlled by the ignition signal voltage to control the charging or discharging time, thereby controlling the primary current cutoff time of the ignition coil according to the engine speed. Since this system controls the primary current energization time to a desired value, it is possible to prevent wasteful power consumption and heating of circuit components when the engine is running at low speeds, and to keep the primary current flowing sufficiently even when the engine is running at high speeds. It is possible to secure current and obtain sufficient ignition energy.

Also, in response to the terminal potential of the capacitor, 1 of the ignition coil
In addition to the terminal potential output of the capacitor, the opening/closing output of the first switch circuit is added in parallel to the input section of the second switch circuit that determines the next current intermittent time, and the terminal potential output of the capacitor is The second switch circuit is opened and closed at a closing rate determined by the closing rate determined by the switching rate and the closing rate determined by the opening/closing output of the first switching circuit. This prevents the reversal operation of the second switch circuit due to The output can provide reliable opening/closing operation to perform ignition operation, thereby improving starting performance.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a potential waveform diagram in a capacitor. In the figure, 3 is a signal generator, 10, 11, 16° 20.2
4, 27, 28, 32 are transistors, 33 is ignition Koinope, 19.37 is capacitor, 6° 7.8, 38, 2
3, 25 are diodes, 4, 5°9.12, 13, 14
,15,17,18,21゜22.26,29,30,
31, 35, and 36 are resistors.

Claims (1)

[Claims] 1 A signal generator driven by the engine (C, a first switch circuit that generates a switching output in response to the output of this signal generator, a capacitor that is charged and discharged by the opening and closing operation of the switch circuit, and a capacitor of this capacitor A transistor that is provided in the charging or discharging circuit and controls the charging or discharging time of the capacitor by receiving a smoothed voltage having a magnitude corresponding to the output voltage of the signal generator as a base, and opens and closes in response to the terminal potential of the capacitor. The opening/closing output of the first switch circuit is added in parallel with the capacitor terminal potential output to a second switch circuit that switches on and off the primary current of the ignition coil, and the second switch circuit. An internal combustion engine ignition device comprising circuit means for opening and closing the second switch circuit at a closing rate determined by a terminal potential output and an opening rate on the side with a larger closing rate determined by the opening/closing amount force of the first switch circuit. .