JPS6239270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device that controls ignition timing so that an ignition device for an internal combustion engine has a predetermined advance characteristic.

As is well known, in internal combustion engines, it is necessary to control the ignition timing with respect to the engine's rotational speed.Generally, the ignition timing is kept constant in the low speed range, and the ignition timing is controlled in stages or at a predetermined level at a certain rotational speed or higher. The angle is advanced along the curve. As an ignition timing control device that achieves this kind of advance characteristic, a mechanical advance device using a centrifuge is well known, but mechanical devices have problems with durability and the advance varies depending on usage conditions. The disadvantages were that the characteristics changed, which had a negative effect on the engine, and that the degree of freedom in the advance angle characteristics was low. Various devices have also been proposed for electrically controlling the ignition timing, but conventional devices have the drawbacks of not being able to achieve a large advance angle, and having poor followability of the ignition timing to the rotational speed.
Furthermore, in order to purify engine exhaust gas, it has recently become necessary to always optimize engine ignition timing.
The ignition timing control device is required to have a so-called two-step advance characteristic in which the angle is advanced by a predetermined width at a first set rotation speed and then advanced by a predetermined width again at a second set rotation speed. However, it has been difficult to obtain such complex advance characteristics with conventional ignition timing adjustment devices.

An object of the present invention is to provide an ignition timing control device for an internal combustion engine ignition system that has good responsiveness to rotational speed, can provide a sufficient advance width, and can easily obtain two-step advance characteristics. Our goal is to provide the following.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The control device of the present invention will be explained in detail below with reference to the illustrated embodiments.

FIG. 1 schematically shows a configuration example of the present invention, in which 1 is an ignition coil having a primary coil 1a and a secondary coil 1b, and 2 is a spark plug loaded on the secondary coil 1b. , 3 is an ignition control circuit that causes a rapid magnetic flux change in the ignition coil at the ignition timing of the engine to generate a high voltage on the secondary side of the ignition coil, and each part of the ignition coil 1 to the ignition control circuit 3 and the present invention The ignition timing control device 4 and the ignition timing control device 4 constitute an ignition device for an internal combustion engine. Here, the ignition control circuit 3 is a capacitor discharge type control circuit that discharges a capacitor charged by a power source (not shown) to the primary coil 1a of the ignition coil via a semiconductor switch such as a thyristor, or A primary current cutoff type control circuit that rapidly cuts off the primary current of the ignition coil by connecting a semiconductor switch in series with the ignition coil and changing the semiconductor switch from a conductive state to a cutoff state at the ignition timing, or Ignition power coil (one of the ignition coils if the ignition coil is placed in a magnet generator)
By connecting a semiconductor switch in parallel to the ignition coil (second coil) and changing the semiconductor switch from a conductive state to a cutoff state at the ignition timing, a high voltage is induced in the ignition power supply coil, and this high voltage is boosted by the ignition coil. Current interrupt type control circuits are known, but the present invention can be applied to any of these control circuits. Regardless of which ignition control circuit is used, the ignition control circuit 3 has a signal input terminal 3a to which a signal for operating the semiconductor switch is applied. The ignition operation is performed when a signal equal to or higher than the trigger level (hereinafter referred to as the trigger level) is input.

The ignition timing control device 4 of the present invention, which controls the ignition timing of the ignition device, includes first to third signal generators 5 that respectively generate first to third signals at predetermined rotation angles of the crankshaft of the engine. It is equipped with 7 to 7. The first to third signal generators 5 to 7 are, for example, incorporated in a magnet generator driven by an internal combustion engine, or from signal generator coils arranged in a signal generator provided separately from the magnet generator. The first to third signal generators 5 to 7 generate first to third signals V ₁ to V ₃ , respectively. The first signal V ₁ and the second signal V ₂ are supplied to the signal synthesis circuit 8
The first signal V ₁ is further input to the waveform shaping circuit 9 . Also the third signal
_V3 is also input to the waveform shaping circuit 10, and signals _V'1 and _V'3 obtained from the waveform shaping circuits 9 and 10 are inputted to the set terminal S and reset terminal R of the RS flip-flop circuit 11, respectively. Reference numeral 12 denotes a bypass circuit consisting of a bypass switch 13 and a current limiting element 14 connected in series to the bypass switch, which outputs an output from the flip-flop circuit 11 when the flip-flop circuit 11 is set. The bypass switch 13 is made conductive by the voltage, and a portion of the output of the signal synthesis circuit 8 is bypassed from the ignition control circuit 3. The signal Vs obtained at the output terminal 8a of the signal synthesis circuit 8 is input to the ignition control circuit 3 as a signal for determining the ignition timing.

Referring to FIGS. 3a to 3k, examples of signal waveforms at each point a, b, c, . . . of the apparatus shown in FIG. 1 are shown with the rotation angle θ of the engine crankshaft taken as the horizontal axis. That is, the first signal generator 5 generates a narrow first signal _V1 as shown in FIG. 3a. Further, as shown in FIG. 3b, the second signal generator 6 generates a wide second signal V 2 that rises at a time when the phase is ahead of that of the first signal V ₁ , and generates a third signal V ₂ . The generator 7 generates a first signal as shown in FIG. 3c.
A narrow third signal V ₃ whose phase is advanced by an angle α with respect to V ₁ is generated. In FIGS. 3a and 3b, Vt is the trigger level of the semiconductor switch in the ignition control circuit 3, and the first signal V ₁ is a change from the idling rotational speed N ₀ (rpm) of the engine to the first set rotational speed.
It is set so that the engine's ignition timing reaches the trigger level Vt in the low rotational speed region up to N ₁ (N ₁ >N ₀ ). In addition, the second signal _V2 does not reach the trigger level Vt in the low rotational speed region as shown by the solid line in FIG. 3b, but in the medium to high rotational speed region higher than the first set rotational speed _N1 . As shown by the broken line in FIG. 3b, the trigger level Vt is set to reach the trigger level Vt before the first signal _V1 . 1st
The signal V ₁ is first processed by the waveform shaping circuit 9 as shown in FIG.
(Point d is not shown in FIG. 1.) After being converted into a signal with a narrow rectangular pulse waveform as shown in FIG. It is converted into a pulse signal V' ₁ as shown in Figure e. Further, the third signal _V3 is converted by the waveform shaping circuit 10 into a signal _V'3 as shown in FIG. 3f. The signals V' ₁ and V' ₃ are respectively supplied to the set terminal S and reset terminal R of the RS flip-flop circuit 11, and the flip-flop circuit 11 is set by the fall of the signal V' ₁ in the negative direction at an angle θ ₁ . Also, the flip-flop circuit 11
is reset at the falling edge of signal _V'3 at angle _.theta.2 , and generates signal Vg which is at a high level from the time it is set until it is reset (from angle _.theta.1 to _.theta.2 ). This signal Vg is input to the side road switch 13, and the side road switch 13 receives the signal
Conducts while Vg is at a high level. Therefore, the voltage Vh across the bypass switch 13 has a waveform that is at a high level during the angle θ ₂ to θ ₁ , as shown in FIG. 3h.

Assuming that the bypass circuit 12 is not provided in the above-mentioned device, the signal combining circuit 8 combines the first signal V ₁ and the second signal V ₂ as shown in FIG. 3i.
A signal Vs having a waveform that is a combination of the two is output, and when this signal reaches the trigger level Vt, an ignition operation is performed. On the other hand, as shown in FIG. 1, a bypass circuit 12 is provided to convert the third signal V ₃ from the angle θ ₁ at which the signal V' ₁ obtained by shaping the waveform of the first signal V ₁ falls. The angle at which the waveform-shaped signal V′ ₃ falls θ ₂
Until then, the bypass switch 13 is made conductive, and the resistance value of the current limiting element 14 is adjusted so that the output of the signal synthesis circuit 8 is substantially short-circuited when the bypass switch 13 is conductive. If the is made sufficiently small, the signal input to the ignition control circuit 3
Vs has a waveform in which a portion whose phase is more advanced than angle _θ2 is cut out, as shown in FIG. 3j. When a signal Vs with such a waveform is input to the ignition control circuit 3,
When the engine is running at low speed, the portion corresponding to the first signal _V1 reaches the trigger level Vt at an angle _θi1 , as shown by the solid line in FIG. 3J, and ignition is performed. As the rotational speed of the engine increases, the peak value of the signal Vs increases, and when the set rotational speed _N1 is reached, the portion corresponding to the second signal _V2 changes to the first signal Vs as shown by the broken line in Fig. 3j. The trigger level Vt is reached at the angle θi ₂ earlier than the portion corresponding to the signal V ₁ of , and the ignition timing advances. In this way, when the output of the signal synthesis circuit 8 is set to be short-circuited when the bypass switch 13 is conductive, the characteristics of the ignition timing θi with respect to the engine rotational speed N are as shown in FIG. The curve ABCDH looks like this.

Next, in the above device, if the resistance value of the current limiting element 14 is increased to a certain extent to limit the amount by which the signal is shorted when the bypass switch 13 conducts, the third
As shown in FIG. k, a portion where the short circuit cannot be completed appears in the waveform of the signal Vs before the angle θ ₂ . The instantaneous value of this portion that cannot be shorted also increases as the engine rotation speed increases, and when the engine rotation speed reaches the second set rotation speed _N2 , the portion that cannot be shorted reaches the trigger level. As a result, the ignition timing advances further. In this case, the characteristics of the ignition timing θi with respect to the rotational speed N are as shown by the curve ABCDEF in FIG. 4, and a characteristic in which the ignition timing is advanced in two steps can be obtained. Here, the second set rotational speed N ₂ can be adjusted as appropriate by adjusting the resistance value of the current limiting element 14.

In the above device, the advance angle characteristic when no bypass circuit is provided is the curve shown in Figure 4.
ABCGEF, and in this case, the curve has a rounded characteristic near the maximum advance angle position (G section of the curve). On the other hand, as in the present invention, a third signal generator 7 is added to generate a signal Vs at an angle θ _2.
By allowing the angle to rise rapidly, the curve can be made into an angular shape at the maximum advance position of the first stage advance angle operation (section C of the curve in Figure 4), and the mechanical advance angle device It is also possible to obtain advance angle characteristics similar to those obtained with .

As mentioned above, in the device of the present invention, since the ignition timing is determined by the voltage waveform of the signal generator,
This eliminates the need for a rotational speed detection circuit with poor responsiveness, and improves the responsiveness of the ignition timing to the rotational speed.

Next, referring to FIG. 2, there is shown an embodiment of the present invention that embodies the configuration of the ignition timing control device 4 shown in FIG. In this example, the first
The third to third signal generators 5 to 7 are composed of signal generating coils provided in a signal generator rotating synchronously with the engine, and one end of each signal generating coil is grounded. The signal synthesis circuit 8 consists of diodes _D1 and _D2 whose cathodes are commonly connected to the output terminal 8a, and the non-grounded side terminals of the signal generation coils constituting the first and second signal generators 5 and 6 are connected to diodes, respectively.
Connected to the anodes of D ₁ and D ₂ . The waveform shaping circuit 9 includes a transistor Tr ₁ whose base is connected to the non-grounded terminal of the first signal generator 5 via a diode D ₃ and whose emitter is grounded, and whose base is connected to the collector of the transistor Tr ₁ . A resistor _R1 is connected between _the base and emitter of the transistor _Tr1 . The base and collector of the transistor Tr ₁ are connected to the power supply line l ₁ connected to the positive terminal of the battery 15 via resistors R ₂ and R ₃ respectively, and the battery 1
The negative terminal of No. 5 is grounded. transistor
The collector of Tr ₂ is connected to the power supply line l ₁ via a resistor R ₄ and also to one end of a capacitor C ₁ , and a resistor R ₅ is connected between the other end of the capacitor C ₁ and ground. In this waveform shaping circuit 9,
When the first signal V ₁ is zero or negative, the base current of the transistor Tr ₁ flows through the diode D ₃ , so the transistor Tr ₁ is in a cutoff state and the transistor Tr ₂ is in a conduction state. When the first signal V ₁ rises positive, the transistor Tr ₁ becomes conductive and the transistor Tr ₂ is cut off, and when the first signal V ₁ becomes zero again, the transistor Tr ₂ becomes conductive again. Therefore, the potential at the collector (point d) of the transistor Tr ₂ becomes a rectangular wave pulse as shown in FIG. 3d. This signal is differentiated by a differentiating circuit consisting of a capacitor C ₁ and a resistor R ₅ and converted into the waveform shown in FIG. 3e.

The waveform shaping circuit 10 includes a transistor Tr ₃ whose emitter is grounded, a resistor R ₆ which is grounded between the base emitter of the transistor Tr ₃ , and a resistor R ₇ which is connected between the base of the transistor Tr ₃ and the positive terminal of the battery 15. A diode connecting the base of the transistor Tr ₃ to the non-grounded terminal of the third signal generator 7
It consists of D ₄ . The operation of this waveform shaping circuit 10 is similar to the operation of the portion from the diode D ₃ to the transistor Tr ₁ of the waveform shaping circuit 9, and when the third signal V ₃ is input, the collector of the transistor Tr ₃ (point f) The potential changes as shown in FIG. 3f.

RS flip-flop circuit 11 is a transistor
This is a known circuit consisting of Tr ₄ and Tr ₅ , resistors R ₈ to R ₁₁ , and a diode D ₅ , and the anode is the transistor Tr _5.
The cathode (set terminal S) of the diode _D5 connected to the base of the transistor Tr4 is connected to the output terminal (point e) of the waveform shaping circuit 9, and the base (reset terminal R) of the transistor _Tr4 is connected to the output terminal of the waveform shaping circuit 10. (point f).

The bypass switch 13 of the bypass circuit 12 is composed of a transistor 13 whose emitter is grounded, and the current limiting element 14 is connected to the collector of the transistor 13 (point h).
and the output terminal _8a of the signal synthesis circuit 8. The base of the transistor Tr ₆ is connected to the power supply line l ₁ through a series circuit of resistors R ₁₃ and R ₁₄ , and the connection point of the resistors R ₁₃ and R ₁₄ is connected to the output terminal (point g) of the flip-flop circuit 11 through a diode D ₆ . It is connected to the.

The operation of the circuit shown in FIG. 2 is similar to that described with reference to FIG. 1, and the signal waveforms at points a to h in FIG. 2 are as shown in FIGS. 3 a to h, respectively. When the resistance value of the variable resistor R12 of the bypass circuit ₁₂ is made sufficiently small, the waveform of the signal Vs becomes as shown in FIG. 3j, and the curve shown in FIG.
If a one-step advance characteristic like ABCDH is obtained and the resistance value of variable resistor _R12 is adjusted to an appropriate value to limit the amount of short circuit, the waveform of signal Vs will become as shown in Figure 3k. A two-step advance angle characteristic like the curve ABCDEF in FIG. 4 is obtained.

In the embodiment shown in FIG. 2, when the voltage of the battery 15 fluctuates, the base current of the transistor _Tr6 fluctuates, which may cause the second set rotational speed _N2 to fluctuate. To prevent this, it is preferable to insert a constant current circuit or a constant voltage circuit to stabilize the power supply of the transistor _Tr6 . Further, instead of using the battery 15, a part of the output of a generating coil in a magnetic AC generator driven by the engine may be rectified and smoothed with a capacitor to be used as a power source.

As described above, according to the present invention, the first signal reaches the trigger level of the semiconductor switch at the ignition timing in the low rotation speed region, and reaches the trigger level earlier than the first signal in the medium to high rotation speed region. A signal synthesis circuit that synthesizes a second signal; and a flip-flop circuit that has a set timing determined by the first signal and a reset timing determined by a third signal whose phase is advanced from that of the first signal. A bypass switch is provided, which is controlled by an output and conducts during a period from when the flip-flop circuit is set until it is reset, and a current limiting element connected in series to the bypass switch. Since the series circuit consisting of the current limiting element and the current limiting element is connected in parallel between the output terminals of the signal synthesis circuit, it is possible to obtain one-stage advance angle characteristics as well as a complex two-stage advance characteristic by adjusting the constant of the current limiting element. There is an advantage that advance angle characteristics can also be easily obtained. Furthermore, since the ignition timing is determined by the waveform of the signal voltage and there is no need to use a rotational speed detection circuit with poor responsiveness, responsiveness to the rotational speed can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention, Fig. 2 is a connection diagram showing a specific embodiment of the invention, and Figs. FIG. 4 is a diagram showing an example of the advance angle characteristic obtained by the device of the present invention. 5...First signal generator, 6...Second signal generator, 7...Third signal generator, 8...Signal synthesis circuit, 11...RS flip-flop circuit, 12
... Side road circuit, 13 ... Side road switch, 14...
...Current limiting element.

Claims (1)

[Claims] 1 Ignition timing that controls the ignition timing of an ignition system for an internal combustion engine that is equipped with an ignition control circuit that causes a sudden change in magnetic flux in an ignition coil by a semiconductor switch that operates when an ignition timing signal of a predetermined trigger level or higher is input. In the control device, a first signal generator that generates a narrow first signal that reaches the trigger level at an ignition timing in a low rotational speed region of the internal combustion engine, and a timing when the phase is advanced than the first signal. a second signal that rises and has a wide width that reaches the trigger level earlier than the first signal in a medium to high rotational speed region of the internal combustion engine;
a signal generator, a third signal generator that generates a third signal having a narrower width at a position that is more advanced in phase than the first signal, and the first signal and the second signal. a flip-flop circuit whose set timing is determined by the first signal and whose reset timing is determined by a third signal; A series circuit of the bypass switch and the current limiting element, comprising a bypass switch rendered conductive by an output signal obtained from a flip-flop circuit, and a current limiting element connected in series to the bypass switch. are connected in parallel between output terminals of the signal synthesis circuit, and the ignition timing signal is output from the output terminal of the signal synthesis circuit.