JPS5820390B2 - Ignition system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for use in internal combustion engines, particularly automobile internal combustion engines, which controls the closing angle of the ignition circuit or the ignition timing by utilizing charging and discharging of a capacitor. .

A conventionally known ignition device that controls an ignition circuit using charging and discharging of a capacitor includes a control circuit that controls charging and discharging of the capacitor, and a detection circuit that detects the voltage of the capacitor and outputs an output according to the detected voltage. The closing angle of the ignition circuit is controlled by the output of this detection circuit.

FIG. 1 shows an example of a device that controls the closing angle of the ignition circuit using charging and discharging of such a capacitor.

In FIG. 1, 300 is an alternator that rotates in synchronization with the engine, 310 is a voltage comparator circuit that converts the output voltage of the alternator 300 into a rectangular wave, and 320 is the output of the voltage comparator circuit 310 that connects the ignition coil to the primary An output circuit that supplies high voltage to a spark plug of an internal combustion engine (not shown) by intermittent current; 330 is a rotational speed-voltage conversion circuit; it creates a DC voltage according to the rotational speed, and converts the DC voltage to a voltage comparison circuit; 3
In addition to 10, closing angle control is performed.

331 is a diode for rectifying the output of the alternator 300, 332 is a capacitor, 333 is a resistor for discharging the capacitor 332, 334 is a transistor for detecting the voltage of the capacitor 332, and 335 is a resistor.

A charging/discharging control circuit is composed of a diode 331, a capacitor 332, and a resistor 333, and a transistor 334 and a resistor 3
35 constitutes a voltage detection circuit.

In such a conventional circuit, the transistor 334 of the voltage detection circuit operates using the discharge current of the capacitor 332 as its base current.

Therefore, the capacitor capacity is such that the base current of the transistor 3340 has almost no effect on the voltage of the capacitor 332.

In other words, in conventional circuits, a large capacitor capacity must be selected in order to be less affected by the detection circuit, and a large capacitor capacity also has the disadvantage of being expensive and bulky. be.

Furthermore, it is difficult to convert the circuit into an IC if the capacitor capacity is large, and even if it is possible to convert the circuit into an IC, the overall size of the circuit will be large and the cost will be high.

In order to eliminate the above-mentioned drawbacks, the present invention has been made to provide a method for controlling the ignition circuit by using the detection circuit to control the current that affects the capacitor voltage so that the capacitor voltage is not affected by the detection circuit when the ignition circuit is controlled using charging and discharging of the capacitor. The purpose is to reduce the capacitance of the capacitor by providing a current cancellation circuit that cancels the current.

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 2 is an electrical circuit diagram showing an embodiment of the device of the present invention.

In FIG. 2, 1 to 92 are resistors, 105 to 153 are transistors, 154 are power transistors, and 155 to 16
6 is a Zener diode, 167 to 190 are diodes, 192 to 204 are capacitors, 210 is an alternating current generator that generates an AC output in synchronization with the internal combustion engine, 211 is a battery, and 212 is an ignition coil.

In addition, 220, which is surrounded by a two-dot chain line, is an alternator 210.
This is a voltage comparator circuit that generates a rectangular wave based on a threshold level determined by the AC output from the closing angle control circuit 230 and the output from the closing angle control circuit 230.

221 is a constant current control circuit that detects the current on the primary side of the ignition coil 212 and limits the current so that it does not exceed a predetermined value; 222 is a rectangular wave from the voltage comparison circuit 220 that turns on the primary side of the ignition coil 2120; This is an output circuit that turns off.

230 is a closing angle control circuit that supplies a signal voltage to the voltage comparison circuit 220 so as to perform optimal closing angle control with respect to the engine speed; 231 is a closing angle control circuit that increases the threshold level of the voltage comparison circuit 220 after the power transistor 154 is turned off; By making it small, it is a waveform correction circuit that is resistant to noise (and can perform optimal closed-angle carp control).

232 is a capacitor 197.232 from a voltage detection circuit that detects the voltage of a capacitor 197 in the closing angle control circuit 230 and a capacitor 199 in the waveform correction circuit 231. '19
This is a current cancellation circuit for canceling the current flowing into the circuit 9.

233 detects a steep falling section of the alternating current output of the alternator 210 in order to eliminate fluctuations in the switching timing due to changes in the bias voltage of the voltage comparator circuit 220, and during that section, the voltage is controlled from the closing angle control circuit 230. This is a differentiation circuit that prevents bias from being applied to the comparison circuit 220.

Reference numerals 501 and 502 are rotation signal output terminals for extracting engine rotation speed pulses from the ignition circuit in order to detect the engine rotation speed.

Next, in the above configuration, first, the constant current control circuit 221,
The basic operation will be explained with the closing angle control circuit 230 omitted.

The alternating current output of alternator 210 controls transistor 106 through input resistor 1,2°4.

When this AC output has positive polarity and transistor 106 is turned on, transistor 107 is turned off and transistor 108 is turned on.
is off, transistor 110 is off, transistor 11
2 is on, transistor 113 is off, transistor 1
21 is off, the power transistor 154 is on, and current flows through the primary side of the ignition coil 212.

Conversely, when the AC output has negative polarity and transistor 106 is turned off, transistors 107, 108, 110, 112
, 113° 121, the power transistor 154 is turned off, the current flowing through the ignition coil 21201 is cut off, a high voltage is generated on the secondary side, and the ignition plug is ignited via a power distributor (not shown). Sparks come alive.

Next, the operation including the constant current control circuit 221 will be explained.

When the current on the primary side of the ignition coil 212 increases, the emitter potential of the transistor 118 rises, and when the primary side current increases beyond a predetermined value based on comparison with the base potential determined by the resistor 34.35, the transistor 118 turns on. The transistors 117 and 116 start to turn on, and the transistor 121 starts to turn on, lowering the base potential of the power transistor 1540 and limiting the current in the primary side of the ignition coil 2120 to a predetermined value.

Further, when constant current control is performed, the transistor 115,
114 is turned on, the collector potential of transistor 114 becomes low and a control signal is output.

Next, the operation including the closing angle control circuit 230 will be explained.

A rectangular wave responsive to the alternating current output of alternator 210 from transistor 111 is applied to closing angle control circuit 230 .

Transistors 137 and 138 generate constant currents i1 and i2.

However, 11=2i2.

When transistor 111 is off, transistors 139,
142 is on, constant current 71 and i2 are each transistor? 42,139.

At the same time, the capacitor 198 is connected to the resistor 67 and the transistor 13.
9.

Next, when transistor 111 is turned on, transistor 1
42,139° is turned off, and the constant current 11 flows through the resistor 71 and the diode 180, and passes through the resistor 79 to the capacitor 1.
Charge 97.

On the other hand, the constant current 12 is passed through the resistor 67 to the capacitor 198.
to charge.

When capacitor 198 is charged, transistor 140 is activated.

The emitter potential rises, resistors 68, 69, diode 17
From the comparison with the base potential of the transistor 140 determined by 8,179, it is found that the transistor 140
turns on, the transistor 141 also turns on, and the constant current 11
begins to flow through the transistor 141 and stops charging the capacitor 197.

Therefore, each time the transistor 111 switches, the capacitor 197 has a constant current i4 of a predetermined amount of time required for the constant current 12 to charge the capacitor 198 to a predetermined voltage.
It will be charged by the battery.

Since the transistor 111 switches in response to the AC output of the alternator 210, the capacitor 197 is eventually charged to a voltage proportional to the engine speed, and this voltage proportional to the engine speed is transferred to the transistors 147 and 14.
8,150, and becomes the emitter output of the transistor 152.

This output is connected to diode 184.185.186, resistor 8
A function generating circuit composed of 2, 83, and 84 produces a nonlinear output that has little change at low speeds and increases as the speed increases.

It is applied as a bias to the base of the transistor 106 via an ode 187 and a resistor 90.

In addition, the output of the transistor 149 is also proportional to the engine speed, and the output of the transistor 149 is proportional to the engine speed.
, 74 provides a non-linear output in which the resistance changes little and the change increases as the speed increases.

When the constant current control circuit 221 is not controlling the output circuit 222, the transistor 114 is off and the transistor 143 is on, so the transistor 149
The output of flows through transistors 144 and 143, and the charging voltage or bias of capacitor 197 does not change.

Next, when the power transistor 154 of the output circuit 222 is under constant current control by the constant current control circuit 221, the transistor 114 is on and the transistor 143 is off. flows.

Since transistors 145 and 146 constitute a current mirror circuit, transistor 146 is turned on, reducing the base potential of transistor 1490 non-linearly with respect to the rotational speed and reducing the bias applied to the base of transistor 106.

A bias applied to the base of the transistor 1060 via the diode 187 and a waveform correction circuit 231 to be described later.
Determine the threshold level to obtain the optimal closing angle with the output of

Next, the operation of the waveform correction circuit 231 will be explained.

A rectangular wave responsive to the AC output of the AC generator 210 from the transistor 111 is applied to a waveform correction circuit 231 in the closing angle control circuit 230.

When power transistor 154 is on, transistor 111 is on and transistor 122 is off.

When the transistor 122 is off, the capacitor 19°9 is charged by the battery 211 via the resistor 41.49 and the diode 176, and the potential at point A increases.

This potential controls the base potential of transistor 1260 via transistors 127 and 128, and
The output of 26 is proportional to the potential at point A.

When transistor 111 is on, transistor 109
is on, and the output of transistor 126 is connected to resistor 53.
, flows through the transistor 109, and the potential at point B is zero.

Next, when the transistor 111 turns off, the transistor 122 turns on and the capacitor 199 is not charged.
Resistor 54, diode 1γ7, transistor 125
The discharge occurs in proportion to the emitter potential of the transistor 126, that is, the potential at point A.

When the potential at point A becomes smaller than the difference Vcc Vz between the voltage VCC at point 6 (the voltage of the battery 211) and the Zener voltage Vz of the Zener diode 166 due to discharge,
Since the diode 177 is reverse biased and turned off, the charge in the capacitor 199 is discharged only to the resistor 54.

Therefore, when the transistor 111 is on, the potential at point B is zero because the transistor 109 is on, and when the transistor 111 is off, the transistor 109 is off, so the potential at point B becomes a potential proportional to the potential at point A. , 107, so that
A threshold level is determined by the diode 187 of the closing angle control circuit 230 and the DC output via the resistor 90 so that the optimum closing angle can be obtained.

Next, the operation of the current cancellation circuit 232 of the closing angle control circuit 230 row will be explained.

Transistors 132, 135. '136 constant current i39
14, i5.1 (l is generated, and currents i3 to i5
are the same current value.

Here, the current i6 serves as a current source for operating the transistors 150 and 152.

Further, almost the entire current i flows through the transistors 127 and 128 that detect the voltage of the capacitor 199 of the waveform correction circuit 231.

(A portion of the current i5 flows slightly as a base current of the transistor 126, but it is negligible.

) Almost the entire current i4 flows through the transistors 147 and 148 which detect the voltage of the capacitor 197 of the closing angle control circuit 230.

(Here, in addition to the current i4, a small amount of the base current of the transistor 1500 also flows through the transistors 147 and 148,
Compared to this current i4, it is very small and can be ignored.

) Current i3 flows through transistors 133 and 134, and the base current of transistor 133 flows through transistors 127 and 1.
It is almost equal to the base current of 47.

Since the transistors 131, 130 and T29 constitute a current mirror circuit, the base current of the transistor 133 flows through the transistor 131, and the transistors 130 and 129 absorb the same current from the bases of the transistors 127 and 147, respectively. .

Therefore, the base currents of transistors 147 and 127G for detecting the voltages of capacitors 197 and 199 are absorbed and canceled by transistors 130 and 129, respectively, so that they have no effect on the charging and discharging of capacitors 197 and 199. (naru)

Therefore, even if the capacitances of the capacitors 197 and 199 are reduced, they can be controlled with high accuracy, and even if integrated into an IC, it is very advantageous in terms of size and cost.

Next, the operation of the differentiating circuit 233 will be explained.

Since the AC output of the AC generator 210 is differentiated by the capacitor 192, the transistor 153 is turned off for a certain period of time when the current output falls sharply, and the transistor 151 is turned off for a certain period of time.
turns on and short-circuits constant current i6.

Therefore, capacitor 197, transistor 147,
While the transistor 151 is on, the DC voltage proportional to the engine speed outputted through the transistors 148 and 150 is
That is, during a certain period of time when the AC output of the AC generator 210 falls sharply, the transistor 151 is grounded, and the transistor 1 is connected to the ground via the diode 181 and the resistor 90.
No bias is applied to the base of 06.

As a result, as shown in FIG. 4, no bias voltage is applied to the base of the transistor 106 during the period for determining the ignition timing, so the threshold level remains a constant level unrelated to the bias.

Therefore, even if the closing angle characteristic, in other words the bias characteristic described above, changes due to a change in the constant of the ignition coil 212 or the discharge characteristics of the spark plug (not shown), for example, the ignition timing will not be affected at all.

In addition, in FIG. 4, A in FIG. 4 a indicates the AC generator 21.
Figure 4 shows the primary current waveform of the ignition coil 212, of which 8 points are the ignition timing, Point C is the time to start energization.

FIG. 3 shows the main structure of another embodiment of the present invention.
400 is a current cancellation circuit, 415 is a voltage detection circuit,
401 is a charging/discharging capacitor, 402 is a capacitor 40
1 charging/discharging control circuit, 403 to 410 transistors,
411.412 is a resistance.

413 is a terminal connected to a constant voltage power supply, and 414 is an output terminal of the voltage detection circuit 415.

By supplying a current approximately equal to the base current of the voltage detection transistor 403 of the capacitor 401 from the transistor 410 to the base terminal of the transistor 4030,
The effect on the capacitor 401 due to the base current of the transistor 403 for detecting the voltage of the capacitor 401 is canceled.

Furthermore, in each of the above-mentioned embodiments, the ignition circuit is controlled by a control circuit that determines the energization start point of the ignition coil 2120, that is, a closing angle control circuit. The same concept can be applied to an ignition timing control circuit that uses a capacitor voltage detection circuit.

As described above, in the present invention, the closing angle of the ignition circuit or the ignition timing is controlled using the charging and discharging of the capacitor, and the detection circuit also controls the capacitor voltage so that the voltage of the capacitor is not affected by the capacitor voltage detection circuit. Since it is equipped with a current cancellation circuit that cancels the current that affects It has the excellent effect of being easy to manufacture and miniaturizing.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an example of a conventional device, Fig. 2 is an electric circuit diagram showing an embodiment of the device of the present invention, and Fig. 3 is a main part electrical circuit diagram showing another embodiment of the device of the present invention. , Figure 4 is the second
127.128, 147.148 which is a waveform diagram of each part used to explain the operation of the illustrated device... Transistors forming the voltage detection circuit, 197, 199° 401
・・・・・・Capacitor, 232.400・・・・・・
Current cancellation circuit, 415... Voltage detection circuit.

Claims (1)

[Claims] 1. A capacitor is charged and discharged according to parameters related to ignition control such as a closing angle or ignition timing. In an ignition device for an internal combustion engine that performs ignition control by detecting the charging voltage of the capacitor with a voltage detection circuit, the voltage detection circuit has a base connected to the capacitor, and generates a voltage on the emitter side according to the base potential. Voltage detection transistor. 1. An ignition device for an internal combustion engine, comprising a current cancellation circuit that supplies a constant current to one of the emitter and base of the transistor and absorbs a constant current having the same value as the supplied constant current from the other.