JPS6138350B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an overspeed rotation prevention device for an internal combustion engine, in particular, a voltage induced by a magnet generator, for example, is short-circuited by a short circuit, and a transistor is used to prevent the short circuit from occurring. A non-contact ignition device for an internal combustion engine that abruptly interrupts the circuit and applies ignition voltage to the ignition plug includes an advance circuit that advances the timing of interrupting the short-circuit current of the short circuit and a retard circuit that delays the timing of interrupting the short-circuit current. When the internal combustion engine rotates at a low speed, the advance angle circuit and the retard angle circuit are not activated, and the short circuit current is cut off near the peak value of the short circuit current waveform of the short circuit, and when the internal combustion engine rotates at a medium speed, the advance angle circuit is turned off. The ignition timing is activated and advanced in steps to correct the ignition timing and prepare to secure the retard width for the next retard, and when the rotation reaches overspeed during high speed rotation, the retard circuit is activated and the ignition timing is significantly increased. The present invention relates to an overspeed rotation prevention device for an internal combustion engine that operates to significantly retard the specified ignition timing of a spark plug and suppress overspeed rotation by performing step retardation.

Conventionally, overspeed prevention devices for internal combustion engines stop the sudden interruption of the short-circuit current that induces high voltage in the secondary winding when the rotational speed of the internal combustion engine rises above a predetermined number of rotations, preventing the ignition plug from igniting. In this way, an increase in the rotational speed of the internal combustion engine is suppressed. Therefore, there is a problem that unburned raw gas is discharged from the internal combustion engine, and it is desired to prevent discharge of unburned raw gas. As a solution to this situation, in order to achieve complete combustion in the internal combustion engine and to suppress the increase in rotational speed of the internal combustion engine, it is necessary to retard the ignition timing from the specified ignition timing (for example, when BTCD is 30°). A method of combustion has been proposed. However, in order to control the increase in the rotational speed of the internal combustion engine by retarding the ignition timing from the specified ignition timing, it is necessary to retard the ignition timing by an angle of about 20 to 25 degrees. By the way, there is a problem that in order to secure the above-mentioned retardation width with the properly adjusted breaking current waveform of the short circuit current as it is, it cannot be achieved unless the widths of the rotor pole and coil core themselves are widened significantly, and this problem also exists. Even if it were possible to solve this problem, it would be necessary to cut off the short-circuit current at a position considerably lower than the peak value of the short-circuit current waveform when the rotational speed of the internal combustion engine is low. In such a state, the interrupting current during low-speed rotation will be interrupted at a low value, and as a result, there is a problem that the spark performance will naturally deteriorate. Furthermore, if the short-circuit current is cut off under these conditions, a problem arises in that reverse sparks occur during extremely low speed rotation, leading to reverse rotation of the internal combustion engine.

The purpose of the present invention is to solve the above-mentioned problems, and when the internal combustion engine rotates at low speed, it is set to shut off at the peak value of the short-circuit current waveform, and when the engine speed increases to medium speed, the step is advanced. This system advances the ignition timing and improves the ignition characteristics through natural retardation from medium speed to high speed, and also prepares to secure the retard width for the next retard, thereby reducing overspeed during high speed rotation. An object of the present invention is to provide an overspeed rotation prevention device for an internal combustion engine that significantly retards the ignition timing by a large step when the engine speed increases, thereby preventing the exhaust of raw gas and suppressing the overspeed rotation of the internal combustion engine. .
This will be explained below with reference to the drawings.

Fig. 1 shows the circuit configuration of an embodiment of the present invention, Fig. 2 shows the ignition timing characteristic curve showing changes in the ignition timing of the present invention, and Fig. 3 shows the no-load voltage induced in the primary winding of the magnet generator. Examples of waveforms, FIGS. 4 to 7, show waveform explanatory diagrams for explaining ignition timing.

In the circuit configuration of an embodiment of the present invention shown in FIG.
1 is a magnet generator, 2 is a magnetic means, 3 is a primary winding, 4 is a secondary winding, 5 is a spark plug, 6 is a short circuit,
Reference numeral 7 indicates a switching transistor constituting the short-circuit circuit 6; 8 indicates an advance circuit which advances the timing of cutting off the short-circuit current flowing through the short-circuit circuit 6; and 9 indicates a control transistor, which is a transistor of the short-circuit circuit 6. 7, 10 is a first rotational speed detection circuit, 11 is a first pulsar coil in which a voltage in phase with the primary winding 3 is induced, 12 is a retard circuit, and 13 is a 14 is a second rotation speed detection circuit; 15 is a first SCR; 16 is a second SCR; 17 is the third
SCR, 18 is a constant voltage diode, 19 to 2
6 is a diode, 27 to 29 are variable resistors, 30
39 to 39 represent resistors, and 40 to 45 represent capacitors.

The operation of the configuration shown in FIG. 1 will be roughly explained as follows.

(1) Assume that the magnetic means 2 is rotated in accordance with the rotation of the internal combustion engine, and a forward voltage as indicated by arrow A in the figure is induced in the primary winding 3.

(2) The current generated by this voltage induced in the primary winding 3 is supplied as a base current to the transistor 7 via the resistor 37 for a while from the time the current rises, and the base current is supplied to the transistor 7 via the resistor 37.
A short-circuit current flows through the short-circuit 6 in a short-circuited state.

(3) During this time, part of the current flowing through the resistor 33 passes through the diode 24 and the resistor 34 to the capacitor 44.
to charge. When the charging voltage charged in the capacitor 44 reaches a predetermined threshold value, the control transistor 9 is turned on.

(4) When the control transistor 9 is turned on, the base current that has been supplied to the transistor 7 is bypassed by the control transistor 9. As a result, transistor 7 is suddenly turned off. That is, the large short circuit current flowing through the short circuit 6 is abruptly cut off, and a high voltage is induced in the secondary winding 4.

(5) The control transistor 9 remains on until the charge in the capacitor 44 is discharged. That is, the charge of the capacitor 44 is transferred to the resistors 34, 35,
It is discharged via a base current circuit which is supplied via 36 to the control transistor 9.

(6) The no-load voltage induced in the primary winding 3 by the rotation of the magnetic means 2, that is, the induced voltage when the illustrated short circuit 6, control transistor 9, etc. are not present, will be described later in FIG. During the period in which the forward voltage in the direction of the arrow A in the drawing exists, the charge in the capacitor 44 continues to exist, and once the control transistor 9 is turned on, this state is maintained. While a voltage in the direction opposite to the arrow A shown in the figure is induced in the primary winding 3, the charge in the capacitor 44 is transferred to the resistor 34,
35 and 33, and the control transistor 9 has returned to its off state. That is, the control transistor 9 returns to a state in which it can be turned on.

(7) Note that the diode 26 bypasses a reverse current while a voltage in the direction opposite to the arrow shown in the figure is induced in the primary winding 3.

When the configuration shown in FIG. 1 rotates at low speed, it operates as described above, and the cutoff timing of the short circuit current flowing through the short circuit 6 is set at the peak value of the short circuit current, as shown in FIG. 4A.

Next, when the rotation speed of the internal combustion engine becomes a medium speed rotation of, for example, 3000 rpm or more, the configuration shown in FIG. 1 operates as follows.

(8) When the rotation speed of the internal combustion engine increases to, for example, 3000 rpm or more, a gate current flows from the first rotation speed detection circuit 10 to fire the third SCR 17 of the advance angle circuit 8, and the third SCR 17 is turned on. arced. As a result, the base current of the transistor 7 is partially bypassed through the variable resistor 29 and the third SCR 17, so that the base current decreases and the collector current, ie, the short circuit current, decreases. Third SCR
The variable resistor 29 is set so that the transistor 7 will not be cut off even if the transistor 17 is turned on and the base current decreases.

(9) When the short circuit current flowing through the short circuit 6 decreases,
The terminal voltage of the primary winding increases as the load becomes somewhat lighter. Consequently, the charging current that charges the capacitor 44 becomes large, and the capacitor 44
The charging voltage of will rise quickly. That is, the control transistor 9 is turned on earlier, and the short-circuit current of the transistor 7 is cut off earlier.

During medium-speed rotation of the configuration shown in FIG. 1, that is, during normal rotation, the advance angle circuit 8 is activated as described above, and the timing for cutting off the short-circuit current flowing through the short-circuit circuit 6 is at the peak of the short-circuit current as shown in FIG. 4B. α ₁ from the value
Advance the angle.

Next, when the rotational speed of the internal combustion engine exceeds a medium-speed rotation, that is, a normal rotation, and increases to a high-speed rotation of, for example, 11,000 rpm or more, the configuration shown in FIG. 1 operates as follows.

(10) When the rotational speed of the internal combustion engine increases to, for example, 11000 rpm or more, the first SCR 15, which is once ignited by the voltage of the capacitor 41 of the second rotational speed detection circuit 14, switches to the first rotational speed detection circuit 10. Due to the electric charge of the capacitor 40, the first
In order to maintain the firing state of the SCR 15, the second SCR 16 of the retard circuit 12 is fired and the retard circuit 12 is activated.

(11) When the retard circuit 12 is activated, that is, when the first SCR 16 is fired, a part of the short circuit current flowing through the short circuit 6 flows through the parallel circuit of the resistor 32 and capacitor 43 via the resistor 33, and is diverted. Therefore, the time required to charge the capacitor 44 becomes longer, and the state in which the control transistor 9 is turned on becomes slower.

(12) Since the control transistor 9 is turned on later, the short-circuit current cutoff time of the transistor 7 is delayed.

When the configuration shown in FIG. 1 rotates at high speed, that is, during overspeed rotation, the retard circuit 12 comes into operation as described above, and the timing for cutting off the short circuit current flowing through the short circuit 6 is determined as shown in FIG. α ₂ from the illustrated cutoff point
Retard the angle. By significantly retarding the _α2 angle, that is, the short circuit current cutoff timing, the ignition plug 5 of the internal combustion engine can be ignited by an angle of approximately 20° to 255° from the specified ignition timing of the internal combustion engine. It becomes possible to suppress an increase in rotational speed. Since the ignition plug 5 is used to ignite, the gas after combustion is always exhausted. FIG. 2 shows these changes in ignition timing.

FIG. 3 represents the no-load voltage induced in the primary winding of the magnet generator shown in FIG. That is, as the magnetic means 2 rotates, the third
As shown in the figure, a forward voltage pulse 46 and opposite voltage pulses 47 and 48 occur before and after it.
One voltage pulse 46 is generated every period T. This forward voltage pulse 46 corresponds to the voltage in the direction of arrow A shown in FIG.

In explaining the operation based on the voltage waveform or current waveform of the configuration shown in FIG. 1, the explanation should be based on the voltage pulses 46, 47, and 48 shown in FIG. Because the width is small, voltage pulse 4 will be used in the following explanation.
The explanation will be made assuming that the pulse widths of 6, 47, and 48 are relatively large. Accordingly, the pulse width of short-circuit current, etc., has also become relatively large.

FIGS. 4A to 4C are short-circuit current waveform diagrams illustrating an example of short-circuit current cutoff timing at each typical rotational speed of an internal combustion engine. 3A shows a state in which the internal combustion engine is rotating at a low rotation speed, and at this time, both the advance angle circuit 8 and the retard angle circuit 12 are not operating. Figure B shows a state in which the internal combustion engine is at a medium rotational speed, that is, at a normal rotational speed, and only the advance angle circuit 8 is activated at this time. This shows that the cut-off timing is advanced by _α1 angle compared to the short-circuit current waveform shown in FIG. FIG. 3C shows a state in which the internal combustion engine is rotating at a high speed, that is, at an overspeed, and the retard circuit 12 is activated at this time. This indicates that the cut-off timing is delayed by _α2 angles compared to the short-circuit current waveform shown in FIG.

Next, the operations of the advance angle circuit 8 and the retard angle circuit 12 will be explained based on voltage and current waveforms.

FIGS. 5A to 5C are explanatory diagrams of current and voltage waveforms when the rotational speed of the internal combustion engine is low. In the figure, numeral 49 is a short circuit current, 50 is a voltage induced in the first pulser coil 11 and is in phase with the voltage induced in the primary winding 3, that is, the short circuit current 49, 51 is the voltage of the capacitor 40, 52 is the voltage induced in the second pulsar coil 13 and has a negative phase relationship with the voltage 50 induced in the first pulsar coil 11, and 53 is the voltage of the capacitor 41. Each represents the voltage of

When the rotational speed of the internal combustion engine is low (for example, 0 to 3000 rpm), the voltage 50 induced in the first pulsar coil 11 is necessary to ignite the third SCR 17, as shown in FIG. 5B. Since the voltage does not rise to a level _L1 sufficient to cause the gate current to flow, the advance angle circuit 8 does not operate. Also, as shown in C of the same figure, the voltage 52 induced in the second pulser coil 13 does not rise to the voltage level _L2 of the capacitor 41 required to ignite the first SCR 15, so the first SCR 15 is turned off. Therefore, the retard circuit 12 does not operate. In this way, the short-circuit current 4 flowing through the short-circuit circuit 6 when both the advance angle circuit 8 and the retard angle circuit 12 do not operate during low-speed rotation.
The cutoff timing of 9 depends on the charging voltage charged in the capacitor 44, and the circuit constants are set so that the cutoff occurs at the peak value of the short circuit current 49, as shown in FIG.

FIGS. 6A to 6D are explanatory diagrams of current and voltage waveforms when the internal combustion engine rotates at a medium speed. In the figure,
Reference numerals 49 to 53 correspond to those in FIG.

When the rotation speed of the internal combustion engine is medium speed rotation, that is, normal rotation (3000 to 11000 rpm), the voltage 50 induced in the first pulser coil 11 and therefore the voltage 51 of the capacitor 40 is as shown in FIG. 6B. Since the voltage rises above the voltage level _L1 that is sufficient to flow the gate current necessary to fire the third SCR 17, when the voltage 51 of the capacitor 40 reaches the voltage level _L1 , the third SCR 17 fires. do. That is, the advance angle circuit 8 is activated. The advance angle circuit 8
The operation when activated is as described in operation explanations 8 and 9 above.
It is explained in

On the other hand, the operation of the retard circuit 12 will be considered as follows. That is, the voltage 52 induced in the second pulser coil 13 increases as shown in C of the same figure, and the voltage 53 of the capacitor 41 also increases as shown in the first SCR.
15 exceeds the voltage level L ₂ of the capacitor 41 required to fire the first SCR 15, and the first SCR 15 fires. The voltage 53 of the capacitor 41 is maintained at a constant voltage by the constant voltage diode 18 between t ₁ and t ₂ as shown in the enlarged view of FIG. The charge accumulated in the capacitor 41 as the voltage 52 induced in the second pulsar coil 13 drops is transferred to the variable resistor 27, the diode 22, and the first
It is discharged in a circuit via the gates of the SCR 15 and the second SCR 16, and in a series circuit of resistors 30 and 31. This discharge characteristic is as shown in the section between t ₂ and _{t 3} shown in FIG. The voltage level of the capacitor 41 required to keep the voltage applied to the first SCR15 has dropped below _L3 , and by the time it reaches _t0 , the first SCR15
is extinguished. Therefore, after t ₀ , capacitor 4
Even if the voltage 51 of 0 is applied to the first SCR 15, the voltage level L ₂ of the capacitor 41 required to flow the gate current to the gate of the first SCR 15 and fire the first SCR 15 Thereafter, the voltage of the capacitor 41 is discharged and drops, and the first SCR 15 is not re-ignited. Therefore, only the advance angle circuit 8 operates when the rotational speed of the internal combustion engine is medium speed.

Note that the first SCR 15 is fired at time _t4 , and the charge charged in the capacitor 40 is discharged through the diode 23, the gates of the first SCR 15, and the second SCR 16 as shown in FIG.

FIGS. 7A to 7D are explanatory diagrams of current and voltage waveforms when the internal combustion engine rotates at a high speed. In the figure,
Reference numbers 49 to 53 correspond to those in FIG.

When the rotational speed of the internal combustion engine increases to high speed rotation, that is, overspeed rotation (11000 rpm or more), the voltage 52 induced in the second pulsar coil 13 increases as shown in Figure C, and the voltage 53 of the capacitor 41 also increases. Exceeds the voltage level L ₂ of the capacitor 41 necessary to ignite the first SCR 15, and the first SCR 1
5 fires. and the voltage 53 of capacitor 41
As shown in the enlarged view of FIG. 1D, the voltage is maintained at a constant voltage in the interval between t ₁ and t ₂ by the constant voltage diode 18.
Voltage 52 induced in the second pulsar coil 13
The charge accumulated in the capacitor 41 as the voltage drops is discharged in a circuit via the variable resistor 27, the diode 22, the gates of the first SCR 15 and the second SCR 16, and the series circuit of the resistors 30 and 31. be done. Since this discharge circuit is always the same regardless of the rotational speed of the internal combustion engine, the capacitor 4
The discharge characteristics from t ₂ to t ₃ after being charged to 1 are determined by the circuit constants of the above-mentioned discharge circuit, and the discharge characteristics during medium-speed rotation and the discharge characteristics during high-speed rotation have the same slope. Become. Moreover, the second rotating high speed
Since the period of the voltage 52 induced in the pulsar coil 13 is smaller than the period during the above-mentioned medium speed rotation, the discharge curve during high speed rotation is shown in the section between t ₂ and t ₃ in Figure D. The discharge starts at t ₀
The discharge occurs closer to the point in time. Then, the charging voltage of the capacitor 41 is discharged, and the voltage is discharged to the voltage level _L3 of the capacitor 41 necessary to keep the voltage sufficient to flow the holding current of the first SCR 15 applied to the first SCR 15. Before (at t ₅ shown in D in the same figure), the voltage 50 of the first pulsar coil 11 has already risen more steeply than during medium-speed rotation, so the terminal voltage 51 of the capacitor 40 It works to maintain the firing state of the first SCR 15. The first SCR 15, which is thus ignited, is not extinguished. That is, at the same time that a forward voltage indicated by arrow A in FIG. 1 is induced in the primary winding 3, the retard circuit 12 is activated. The operation when the retard circuit 12 is activated is explained in operation explanations 10 to 12 above.

Note that the voltage 51 of the capacitor 40 is the voltage of the first SCR.
The voltage level shown to be shorted by 15
L ₁ or less, and the advance angle circuit 8 is placed in a non-operating state.

As explained above, according to the present invention, it is possible to significantly retard the ignition timing when the internal combustion engine reaches an overspeed, and it is possible to suppress the overspeed circuit while sending sparks to the ignition plug. There is no need to exhaust raw gas from combustion. Since the angle can be advanced during normal rotation, it is possible to contribute to improving the ignition characteristics through natural retardation.

[Brief explanation of the drawing]

Fig. 1 shows a circuit configuration of an embodiment of the present invention, Fig. 2 shows an ignition timing characteristic curve showing changes in ignition timing of the present invention, and Fig. 3 shows induced energy in the primary winding of the magnet generator shown in Fig. 1. No-load voltage waveforms shown in Figures 4 to 7
The figure shows a waveform explanatory diagram for explaining ignition timing. In the figure, 1 is a magnet generator, 2 is a magnetic means, and 3 is 1
Next winding, 4 is a secondary winding, 5 is a spark plug, 6 is a short circuit, 7 is a transistor, 8 is an advance angle circuit, 9 is a control transistor, 10 is a first rotation speed detection circuit, 1
1 is the first pulsar coil, 12 is the retard circuit, 1
3 is the second pulsar coil, 14 is the second rotation speed detection circuit, 15 is the first SCR, 16 is the second
17 is a third SCR, 18 is a constant voltage diode, 19 to 26 are diodes, 27 to 29 are variable resistors, 30 to 39 are resistors, and 40 to 45 are capacitors, respectively.

Claims (1)

[Scope of Claims] 1. Magnetic means for generating a moving magnetic field in response to rotation of the internal combustion engine, and 1. magnetically coupled to the magnetic means.
ignition coil means comprising a primary winding and a secondary winding; control means for controlling the voltage and current of the primary winding of the ignition coil means; and ignition means connected to the secondary winding of the ignition coil means. The voltage and current induced in the primary winding by the magnetic means are controlled by the control means to generate a high voltage in the secondary winding to ignite the ignition means. A non-contact ignition device for an internal combustion engine includes a first rotational speed detection circuit that includes a first pulser coil magnetically coupled to the magnetic means and detects the rotational speed of the internal combustion engine; The base current is shunted to the base of the transistor of the short circuit that short-circuits a predetermined forward current of the voltage induced in the line, thereby reducing the short circuit current of the short circuit. A parallel circuit is configured for an advance circuit that advances the cut-off timing and a timing circuit that determines the conduction timing of the control transistor that controls the transistor in the short circuit to delay the conduction timing of the control transistor. A retard circuit is provided to delay the cut-off timing, and when the internal combustion engine is running at low speed, the advance angle circuit and the retard circuit are deactivated, and when the internal combustion engine is running at medium speed, the advance angle circuit is activated to advance the angle by steps. In addition to correcting the ignition timing of the ignition means, preparations are made to secure the retard width at the next retard, and the retard circuit is activated during overspeed rotation to perform a large step retard. Features: Overspeed rotation prevention device for internal combustion engines. 2 Claims characterized in that the advance angle circuit is provided with a series circuit of a third SCR and a resistor, and ignition of the third SCR is performed by the first rotation speed detection circuit. The overspeed rotation prevention device for an internal combustion engine according to item 1. 3 said retard circuit comprises a second pulser coil magnetically coupled to said magnetic means;
a first SCR for controlling the parallel circuit, the first SCR having a second rotational speed detection circuit that is fired by a voltage induced in the second pulsar coil; A configuration in which a discharge current from the rotation speed detection circuit flows through the first SCR,
Claim 1, characterized in that the parallel circuit is controlled by maintaining the ignition of the first SCR by a discharge current discharged from the first rotation speed detection circuit during overspeed rotation. An overspeed rotation prevention device for an internal combustion engine as described in .