JPS6226619Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine overspeed prevention device that prevents overspeed of an internal combustion engine ignited by a non-contact ignition device.

This type of overspeed prevention device detects the engine rotation speed (rpm) by utilizing the fact that the output of the negative half cycle that does not contribute to the ignition operation of the exciter coil of the ignition device changes with the rotation speed. Some engines short-circuit the output of the positive half cycle of the exciter coil when the number reaches a set value, thereby stopping the ignition operation and lowering the engine speed. However, when detecting the rotation speed using the output of the negative half cycle of the exciter coil in this way, the rise of the output of the negative half cycle of the exciter coil is caused by the armature reaction that occurs when the output of the exciter coil is short-circuited. The delay causes an error in the detection of the rotational speed, which has the drawback that the overspeed prevention operation cannot be carried out stably. In addition, when the rotation speed is detected by the output of the exciter coil, the rotation speed may vary due to variations in the amount of magnetization of the magnet of the magnet generator in which the exciter coil is installed, and variations in the air gap between the stator and rotor. Errors occurred in detection, and variations occurred in the set rotational speed at which the overspeed prevention operation was started.

Therefore, Utility Model Application Publication No. 56-71955 and Utility Model Application No. 56-71955
As shown in Publication No. 113176, the engine rotation speed is detected using the signal of the pulsar coil that outputs a signal that determines the ignition position of the internal combustion engine, and when the engine rotation speed reaches the set value, the signal is sent to the exciter coil. A device was proposed that short-circuited the output of the positive half cycle of the exciter coil by making the over-rotation prevention thyristors connected in parallel conductive. This conventional device detects the rotational speed of the engine by utilizing the discharge of a capacitor charged by the output of the pulsar coil.
However, since the discharge waveform of the capacitor is not linear, there is a problem in that the set rotational speed of the engine cannot be detected accurately. Further, since the set rotation speed varies depending on the capacitance of the capacitor, there is a problem that the set rotation speed cannot be easily and finely adjusted.

The purpose of this invention is to be able to detect the rotational speed without being affected by the armature reaction when the output of the exciter coil is short-circuited, and to always be able to accurately detect the rotational speed. An object of the present invention is to provide an internal combustion engine overspeed prevention device that stabilizes the operation.

In order to solve the above problems, the present invention supplies ignition energy with the output of one half cycle of an exciter coil that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine. In an internal combustion engine overspeed prevention device that prevents the rotation speed of an internal combustion engine ignited by a non-contact ignition device that determines the ignition position by the output of one half cycle of a pulser coil that generates a signal from exceeding a set value, an exciter coil is used. A thyristor for over-rotation prevention that is connected in parallel to the exciter coil so as to be conductive during one half cycle of the exciter coil and short-circuits the output of one half cycle of the exciter coil when conductive, and the output of the pulsar coil. and a monostable multivibrator that uses the output of the power circuit as a power input and outputs a rectangular wave signal of a constant time width at the rising edge of one half cycle of the pulsar coil. There is. In the present invention, the time width of the rectangular wave signal output by the monostable multivibrator and the phase relationship between the outputs of the exciter coil and the pulsar coil are determined such that the rectangular wave signal disappears when the rotational speed of the internal combustion engine is less than a set value. After that, the output of one half cycle of the exciter coil rises, and when the rotation speed exceeds the set value, the output of one half cycle of the exciter coil rises while the square wave signal is being generated. setting, and supplies a square wave signal to the over-speed prevention thyristor as a firing signal.

The structure of the present invention will be explained in detail below with reference to the illustrated embodiments.

Figure 1 shows an embodiment of the present invention, in which 1 is a capacitor discharge type ignition circuit that constitutes the main part of the non-contact ignition system, and 2 is placed in a magnet generator that rotates in synchronization with the engine. The exciter coil 3 is located in the same generator as the exciter coil and supplies the ignition energy with the output of one half cycle, and the output of one half cycle is used to determine the ignition position of the engine and the power supply circuit. A pulser coil 4 used as a power source includes a primary coil 4a and a secondary coil 4 with one end grounded.
5, 5' are spark plugs connected between both ends of the secondary coil 4b of the ignition coil and ground, and the ignition circuits 1 to 5,
Each part of 5' constitutes a non-contact ignition device for an internal combustion engine.

The ignition circuit 1 includes an ignition energy storage capacitor 101 and a thyristor 10 that discharges the charge of the capacitor 101 to the primary coil 4a of the ignition coil.
2, one end of the capacitor 101 is connected to the non-ground terminal of the primary coil 4a of the ignition coil 4, and the other end is connected to the non-ground terminal of the exciter coil 2 through diodes 103 and 104 whose cathodes are located on the capacitor 101 side. It is connected. The thyristor 102 has its anode connected to the connection point between the capacitor 101 and the diode 103, and its cathode grounded. The gate of the thyristor 102 is connected to the other end of a resistor 105 whose one end is grounded, and also to one end of a capacitor 106 and a resistor 107, and the other ends of the capacitor 106 and the resistor 107 are commonly connected to the cathode of a diode 108. The pulsar coil 3 is connected between the anode of the diode 108 and the ground, and the pulsar coil 3 connects the diode 108, the capacitor 106, and the resistor 1.
An ignition signal is given to the thyristor 102 through the parallel circuit 07. A thyristor 110 is connected between the connection point between the diodes 104 and 103 and the ground, with the cathode on the ground side.
A voltage dividing circuit including a series circuit of resistors 111 and 112 is connected in parallel between the anode and cathode of the thyristor 110. The voltage dividing point of this voltage dividing circuit is connected to the thyristor 11 through the Zener diode 113.
A resistor 114 is connected in parallel between the gate and cathode of the thyristor 110. In addition, the diode 104 and the exciter coil 2
A series circuit of a diode 115 and a resistor 116 with the anode facing the ground is connected between the connection point of It's summery.

In the above ignition system, when the exciter coil 2 generates an output in one half cycle (hereinafter referred to as a positive half cycle) in the direction of the solid arrow shown in the figure, the capacitor 101 is connected to the polarity shown in the figure through the diodes 104 and 103 and the primary coil 4a. is charged to. Next, when an output of one half cycle (hereinafter referred to as a positive half cycle) in the direction of the solid arrow shown in the figure is generated in the pulsar coil 3, an ignition signal is given to the thyristor 102, and the thyristor 102 becomes conductive, and the capacitor 101 is connected to the thyristor 102 and 1
Next, a discharge occurs through the coil 4a. This discharge causes a large magnetic flux change in the iron core of the ignition coil 4,
A high voltage is induced in the secondary coil 4b. This generates sparks in the spark plugs 5, 5', and the engine is ignited. The ignition coil 4 is a so-called simultaneous ignition type coil, and the ignition plugs 5, 5' are installed in two different cylinders such that one is at the ignition timing and the other is at the end of the exhaust stroke. In the above ignition system, the thyristor 110 is provided to prevent the charging voltage of the capacitor 101 from exceeding a predetermined value, and when the instantaneous value of the output voltage of the exciter coil 2 reaches a predetermined value, the Zener diode 113 becomes conductive. Thyristor 110
An ignition signal is applied to the thyristor 110, and the exciter coil 2 is short-circuited by the conduction of the thyristor 110. As a result, charging of the capacitor 101 is stopped, and the capacitor 101 is prevented from being charged to an excessive voltage exceeding a predetermined value.

In order to prevent overspeed of the engine ignited by the ignition device, an overspeed prevention device 6 is provided, and this overspeed prevention device consists of an exciter coil short circuit 7, a monostable multivibrator 8, and a power supply circuit. 9 and a trigger waveform detection circuit 10.

The exciter coil short circuit 7 includes an over-rotation prevention thyristor 701 connected in parallel to the exciter coil 2, a resistor 702 whose one end is connected to the gate of the thyristor 701, and a resistor 702 connected to the gate of the thyristor 701.
A resistor 703 connected in parallel between the gate and cathode of
It is made up of.

The monostable multivibrator 8 includes inverters 801 and 802 made of CMOS integrated circuits, and a resistor 80.
3 to 806, and capacitors 807 and 808. More specifically, the input terminal of inverter 801 is connected to one end of capacitor 807 through resistor 803, and the output terminal of inverter 801 is connected to the input terminal of inverter 802 through capacitor 808 and resistor 804. The output terminal of the inverter 802 is connected to the resistor 8.
05 to the connection point between the resistor 803 and the capacitor 807, and the capacitor 808 and the resistor 80
One end of a resistor 806 is connected to the connection point with 4.

The power supply circuit 9 includes a diode 901 whose anode is connected to the non-grounded terminal of the pulser coil 3;
The cathode is connected to a diode 901 through a resistor 902.
A Zener diode 903 connected to the anode of the
The cathode of the Zener diode 903 is connected to the connection point between the capacitor 808 and the resistor 804 through the resistor 806 of the multivibrator 8. This power supply circuit 9 is the pulsar coil 3
The capacitor 904 is charged by one half cycle (positive half cycle), and a predetermined voltage necessary to drive the multivibrator 8 is supplied to the resistor 902 for a certain period even when the pulser coil 3 is outputting the other half cycle. It is output to the connection point with the Zener diode 903.

The trigger waveform detection circuit 10 includes a diode 11 whose anode is connected to the non-ground terminal of the pulsar coil 3, a series circuit of resistors 12 and 13 connected between the cathode of the diode 11 and the ground, and a resistor 13.
The Zener diode 14 is connected in parallel with the anode on both ends of the multivibrator 8 and the cathode of the Zener diode 14 is connected to the multivibrator 8.
is connected to the other end of the capacitor 807.

Next, the operation of the above embodiment will be explained. Figures 2A to 2E show the voltage waveforms relative to the ground at the points marked A to E in Figure 1 with respect to time t, and the pulser coil 3 is shown in Figure 2A. An alternating current signal V _s such as this is generated in synchronization with the rotation of the engine, and the exciter coil 2 outputs an alternating current voltage V _e as shown in FIG. At the current time t ₁ , the capacitor 101 is charged, and the capacitor 101
The terminal voltage V _c increases as shown in FIG.
When the output of the positive half cycle of the pulser coil 3 that rises at time _t2 exceeds a certain level, the potential at the output terminal of the inverter 801 of the monostable multivibrator 8 is increased by the resistor 805 and capacitor 808 as shown in FIG. 3E. The level changes from a low level to a high level for a period T determined by a predetermined time constant. This rectangular wave signal _vq of time width T is applied to the gate of thyristor 701 through resistor 702, so thyristor 701 becomes conductive, but if the engine speed (rpm) is less than the set value, time width T
Since the positive half-cycle output of the exciter coil 2 does not rise during the period in which the rectangular wave signal is generated, the thyristor 701 does not conduct. Therefore, the exciter coil 2 is never short-circuited. In this case, when the output of the positive half cycle of the pulser coil 3 reaches the trigger level vt of the thyristor 102 at time _t3 , the thyristor 102
conducts and ignition is performed. The time width T of the rectangular wave signal _Vq obtained from the monostable multivibrator 8 is constant regardless of the engine speed, but the time when the positive half cycle of the exciter coil 2 rises depends on the engine speed. It progresses as it rises. When the rotation speed reaches the set value, the output of the positive half cycle of the exciter coil 2 starts to rise within the period T during which the rectangular wave signal _Vq is generated, and the thyristor 701 becomes conductive. As a result, the output of the positive half cycle of the exciter coil 2 is short-circuited, so that the capacitor 101 is no longer charged and no ignition operation is performed. Therefore, the rotation of the engine is suppressed and the rotational speed is lowered below the set value.

In the above embodiment, the time from the rise of the square wave signal V _q to the rise of the positive half cycle of the exciter coil 2 is T', the constant is k, and the rotation speed is N.
(rpm), there is the relationship T'=k/N.
At the rotation speed where the relationship T'>T (N<k/T) holds, the ignition operation is performed without any problem.
A misfire occurs at a rotation speed where the relationship T'≦T (N≧k/T) holds. Therefore, the set rotational speed N _c at which the overspeed prevention operation is started is given by N _c =k/T.

In the above embodiment, the diode 11 is for blocking the voltage of the negative half cycle of the pulser coil 3 to protect the trigger circuit of the monostable multi-circuit. Further, if the trigger waveform detection circuit 10 can use a Zener diode 14 having a capacity that allows the current given through the diode 11 and the resistor 12 to flow, the resistor 13 can be omitted.

In the above embodiment, the monostable multivibrator is configured using a CMOS IC inverter, but the monostable multivibrator may also be configured using other elements of the CMOS IC. in this way
When a monostable multivibrator is configured using a CMOS IC, it can be driven with a small amount of power, so even if the output of the positive half cycle of the pulsar coil is used, it does not affect the operation of the ignition system.

As described above, according to the present invention, a monostable multivibrator is provided that outputs a rectangular wave signal with a constant time width at the rising edge of one half cycle of the pulsar coil, and the generation period of this rectangular wave signal and this rectangular wave signal are The set rotation speed at which the overspeed prevention operation starts is determined by the relationship between the rise of the output and the rise of the output of one half cycle of the exciter coil, so it can be easily set by simply adjusting the signal width of the square wave signal. This has the advantage that the number of revolutions can be set and that the set number of revolutions can always be kept constant. Furthermore, according to the present invention, a power supply circuit that outputs a predetermined voltage using the output of the pulsar coil is provided to drive a monostable multivibrator, so the present invention can be easily applied to internal combustion engines that do not have batteries. Can be done.

In the above embodiment, a capacitor discharge type circuit was used as the ignition circuit, but a semiconductor switch was provided in parallel with the exciter coil and the primary coil of the ignition coil, and was controlled on and off by the output of the pulsar coil. A current interrupting type ignition circuit may be used in which the ignition operation is performed by switching the semiconductor switch from a conductive state to a disconnected state.

In the above description, the pulsar coil is placed in the same magnet generator as the exciter coil, but the present invention can also be applied when the pulsar coil is placed in a signal generator separate from the exciter coil.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing an embodiment of the present invention, and FIGS. 2A to 2E are voltage waveform diagrams of respective parts indicated by symbols A to E in FIG. 1, respectively. 1...Ignition circuit, 2...Exciter coil, 3
...Pulsa coil, 4...Ignition coil, 5,5'
...Spark plug, 6...Overspeed prevention device, 701
... Thyristor for over-rotation prevention, 8 ... Monostable multivibrator, 9 ... Power supply circuit, 10 ... Trigger waveform detection circuit.

Claims (1)

[Scope of utility model registration request] ignition energy is supplied by the output of one half cycle of an exciter coil that induces an alternating current voltage in synchronization with the rotation of the internal combustion engine, and one half cycle of a pulser coil that generates an alternating current signal in synchronization with the rotation of the internal combustion engine. In an internal combustion engine overspeed prevention device that prevents the rotational speed of an internal combustion engine ignited by a non-contact ignition device that determines the ignition position based on the output from exceeding a set value, the exciter coil is configured to conduct during one half cycle. an over-rotation prevention thyristor that is connected in parallel to the exciter coil and short-circuits the output of one half cycle of the exciter coil when conductive; and a thyristor that outputs a predetermined voltage using the output of the pulsar coil. a monostable multivibrator that uses the output of the power circuit as a power input and outputs a rectangular wave signal with a constant time width at the rising edge of the one half cycle of the pulsar coil; is less than a set value, the rectangular wave signal disappears, and then the output of one half cycle of the exciter coil rises, and when the rotation speed exceeds the set value, the rectangular wave signal is generated. The time width of the rectangular wave signal and the phase relationship between the outputs of the exciter coil and the pulsar coil are set so that the output of one half cycle of the exciter coil rises during the period in which the rectangular wave signal is applied to the thyristor. An internal combustion engine overspeed prevention device characterized in that an arc signal is supplied.