JPS5820392B2 - Ignition system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition device for an internal combustion engine, and particularly to one that controls the current conduction angle of an ignition coil.

In the conventional non-contact ignition system with a closed angle control device, the AC output of an alternator that rotates in synchronization with the internal combustion engine and the DC output proportional to the engine speed from the bias up circuit are input to a voltage comparison circuit. In addition, the primary current of the ignition coil is intermittent by a square wave output according to the power of both personnel, and the energization angle of the ignition coil is expanded as the engine speed increases.
In addition, the DC output from the bias up circuit is reduced by the bias down circuit for the time period during which the constant current control circuit that limits the primary current of the ignition coil to a predetermined value is controlling the power transistor at a constant current. The closing angle is controlled by reducing the energization angle.

Here, the AC output of the AC generator rotating in synchronization with the internal combustion engine has the waveform shown in FIG.

The threshold level for this AC output changes from Vl to V2 as the engine speed increases.

At this time, the power transistor, which was turned off at Pl and turned on at Ql, is turned off at P2 and turned on at Q2, greatly expanding the closing angle.

Therefore, during low-speed rotation, if the bias changes slightly, the closing angle changes greatly, and during high-speed rotation, the predetermined closing angle cannot be obtained unless the bias changes significantly.

Therefore, as shown in Fig. 2, the characteristics of the closing angle with respect to the engine speed are as follows. As the closing angle increases during low-speed rotation, the time the power transistor is under constant current control becomes longer, and the power transistor generates heat.

Therefore, the heat sink of the power transistor becomes larger,
This has the disadvantage that the entire ignition device becomes larger.

Furthermore, if an attempt is made to suppress heat generation by shortening the time period during which the power transistor is under constant current control, the closing angle becomes like C, and the closing angle at high speed becomes smaller.

That is, there is a drawback that the voltage generated by the ignition coil is reduced.

In order to solve the above-mentioned drawbacks, the present invention has a configuration in which the AC output of an alternator that rotates in synchronization with the internal combustion engine and the output from a waveform correction circuit that controls the closing angle especially at low speeds are added to a voltage comparison circuit. By doing so, we can perform optimal closing angle control from low speeds, suppress heat generation of the power transistor,
In addition to downsizing the ignition device, the waveform correction circuit biases the output voltage of the alternator for a predetermined period of time so that after the current in the ignition coil is cut off, the output voltage of the alternator suddenly changes in the opposite direction to the direction of the change. By adding it to the voltage comparison circuit, the purpose is to prevent malfunctions caused by ignition noise.

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

FIG. 3 is an electrical circuit diagram showing an embodiment of the device of the present invention.

In FIG. 3, 1 to 92 are resistors, of which 12 is a bias resistor, 105 to 153 are transistors,
Among them, 106 is an input transistor, 109 is a bias blocking transistor, and 126 is a bias applying transistor.

154 is a power transistor, 155-166 are Zener diodes, 167-190 are diodes, 192-
204 is a capacitor, 210 is an alternator that generates AC output in synchronization with the internal combustion engine, 211 is a battery, 21
2 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 this current so that it does not exceed a predetermined value; 222 is a constant current control circuit that turns on the primary side of the ignition coil 2120 by a rectangular wave from the voltage comparison circuit 220; , 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 for 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; This is a waveform correction circuit that is made smaller to make it more resistant to noise and to perform optimal closing angle control.

232 is a capacitor 197.199 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.
This is a current cancellation circuit for canceling the current flowing into the circuit.

233 detects a steep falling section of the AC output of the alternator 210 in order to eliminate fluctuations in ignition timing due to changes in the bias voltage of the voltage comparator circuit 220, and during that section, the bias up circuit 234 detects a steep falling section of the AC output of the alternator 210. This is a differentiation circuit that prevents the application of bias to 220.

Reference numeral 234 designates a closing angle expansion circuit that enables optimum closing angle control by changing the threshold voltage of the voltage comparison circuit 220 in accordance with the engine speed and the time period during which the power transistor 154 performs constant current control. This is a bias up circuit.

Reference numerals 501 and 502 are rotation signal output terminals for taking out 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 input transistor 106 via input-resistors 1, 2, 4.

When this AC output has positive polarity and input transistor 106 is turned on, transistor 107 is turned off and transistor 1
08 is off, the transistor 110 is off, the transistor 112 is on, the transistor 113 is off, the transistor 121 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 input transistor 106 is turned off, transistors 107, 108 . .

The power transistor 154 is turned off via 110.112, 113, and 121, the current flowing to the primary side of the ignition coil 212 is cut off, and a high voltage is generated on the secondary side, which connects a power distributor (not shown). An ignition spark is generated through the ignition plug.

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 increases, and when the primary side current increases beyond a predetermined value based on comparison with the base potential determined by the resistors 34 and 35, the emitter potential of the transistor 118 increases. starts to turn off from on, transistors 117 and 116 start to turn on,
Transistor 121 begins to turn on, lowering the base potential of power transistor 1540 and limiting the current in the primary side of ignition coil 212 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 from transistor 111 in response to the AC output of alternator 210 is applied to bias up circuit 234 .

Transistors 137 and 138 have constant current i1. Generate i2.

However, 1l=2i2.

When transistor 111 is off, transistor 139
, 142 are turned on, and the constant current i1. i2 flows through transistors 142 and 139, respectively.

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 and 139 are turned off, and a constant current i flows through the resistor 71 and the diode 180, and then passes through the resistor 79 to the capacitor 197.
to charge.

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

When the capacitor 198 is charged, the emitter potential of the transistor 140 increases, and the resistor 68°69 and diode 1
From the comparison with the base potential of the transistor 140 determined by 78 and 179, it is found that the transistor 14
0 is turned on, the transistor 141 is also turned on, and the constant current 1
1 begins to flow through transistor 141 and stops charging capacitor 197.

Therefore, capacitor 197 is charged by constant current 11 for a predetermined amount of time required for constant current 12 to charge capacitor 198 to a predetermined voltage each time transistor 111 switches.

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.
It becomes the emitter output of transistor 152 through 8°150.

Connect this output to diodes 184, 185°186, resistor 8
The function generating circuit composed of 2, 83, and 84 generates a nonlinear output that has little change at low speeds and increases as the speed increases, and supplies it as a bias to the base of the input transistor 106 via a diode 187 and a resistor 90. Adding.

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 with little variation at low speeds and larger variation as the speed increases.

When the constant current control circuit 221 does not control the output circuit 222, the transistor.

Since transistor 114 is off and transistor 143 is on, the output of transistor 149 is output from transistor 144,
143, and the charging voltage or bias of capacitor 197 remains unchanged.

Next, the output circuit 2220 is controlled by the constant current control circuit 221.
When the 1 power transistor 154 is under constant current control, the transistor 114 is on and the transistor 143 is off, so the output of the transistor 149 flows through the transistors 144 and 145.

Since the transistors 145 and 146 constitute a current mirror circuit, the transistor 146 is turned on, reducing the base potential of the transistor 149 non-linearly with respect to the rotation speed, and reducing the bias applied to the base of the input transistor 106.

A threshold level is determined so that an optimal closing angle can be obtained by the bias applied to the base of the input transistor 106 via the diode 187 and the output of the waveform correction circuit 231, which will be described later.

FIG. 6 shows the output voltage characteristics of the bias up circuit 234 with respect to the engine speed.

When the time width during which the power transistor 154 performs constant current control increases, the characteristics change from F to G in FIG. 6.

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 transistor 122 is off, capacitor 199 is a resistor of 41.49 and a diode.

The capacitor 199 is charged to a certain value according to the battery voltage while the transistor 122 is off.
The potential at point A increases in accordance with this charging voltage.

This potential controls the base potential of the bias application transistor 1260 via the transistors 127 and 128, and the output of the bias application transistor 126 is proportional to the potential at point A.

When the transistor 111 is on, the bias blocking transistor 109 is on, the output of the bias applying transistor 126 flows through the resistor 53 and the bias blocking 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 no longer charged.
Resistor 54 and diode 177, transistor 125
The discharge occurs in proportion to the emitter potential of the bias application transistor 126, that is, the potential at point A.

When the potential at point A becomes smaller than the difference between voltage Vcc at point 0 (voltage of battery 211) and Zener voltage VzO of Zener diode 166 (Vcc - Vz) due to discharge, diode 177 is reverse biased and turned off, so capacitor 199 The charged charge is discharged only through the resistor 54.

Therefore, the potential at point B, which is connected to the bias resistor 12 via the diode 167, is zero when the transistor 111 is on because the bias blocking transistor 109 is on, and when the transistor 111 is off, the potential of the bias blocking transistor 109 is zero. is off, the potential becomes proportional to the potential at point A, and at this potential the emitter potential of input transistor 106 and transistor 107 (bias resistor 12
Therefore, the threshold level is determined by the DC output via the diode 187 and the resistor 90 of the closing angle control circuit 230 so that the optimum closing angle can be obtained.

Next, the current cancellation circuit 2 in the closing angle control circuit 230
The operation of No. 32 will be explained.

Constant current i3.
i4゜i5. i6 is generated, and currents i3 to i6 have the same current value.

Almost the entire current i5 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 the base current of the transistor 126, but it is negligible.

) The transistors 147 and 148 that detect the voltage of the capacitor 197 of the bias up circuit 234 are connected to the current i4.
Almost the entire current flows.

Current i3 flows through transistors 133 and 134, and the base current of transistor 1330 flows through transistor 127゜1.
It is almost equal to the base current of 47.

Since the transistors 13L130 and 129 constitute a current mirror circuit, the base current of the transistor 1330 flows through the transistor 131, and the transistors 130 and 129 each pass the same current through the transistor 131.
It sucks from the base of 27,147.

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

Therefore, even if the capacitance of the capacitors 197 and 199 is reduced, accurate control is possible, and the IC.

It is also 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 AC output falls sharply, and the transistor 151 is turned off for a certain period of time.
turns on.

Therefore, capacitor 197, transistor 147,
While the transistor 151 is on, the DC voltage proportional to the engine rotation speed output through the transistor 148 and 150 is
That is, for a certain period of time when the AC output of the AC generator 210 falls sharply, the bias applied to the base of the input transistor 1060 is grounded by the transistor 151 and is applied to the base of the input transistor 1060 via the diode 187 and the resistor 90.

As a result, as shown in FIG. 4, no bias is applied to the base of the input 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.

Next, the operation for controlling the closing angle will be explained using FIGS. 4 and 5.

A in FIGS. 4 and 5 indicates the AC output voltage of the AC generator 210, which has a portion where the slope changes gently in one direction and a portion where the slope changes steeply in the other direction. The threshold level (voltage) of the input transistor 106 of the voltage comparison circuit 220 with respect to the voltage comparison circuit 220 is shown.

Point e is the ignition timing, and point f is the timing at which energization of the ignition coil 212 starts.

Incidentally, C in FIG. 4 indicates the threshold voltage when the power supply voltage drops, and point g is the time when the current supply starts at that time.

FIG. 4 shows the state at low speed, and FIG. 5 shows the state at high speed.

In FIG. 4 showing the low speed state, T4 is the time during which the DC output from the bias up circuit 234 is grounded by the transistor 151 of the differentiating circuit 233 for a certain period of time.
After ignition at point e, the threshold voltage changes from point e to point h according to the output of the waveform correction circuit 231.

The capacitor 199 of the waveform correction circuit 231 starts discharging from point h.

T is the threshold voltage time determined only by the output of the waveform correction circuit 231, and T1 is the time of the threshold voltage determined only by the output of the waveform correction circuit 231.
This is the time during which the capacitor 199 is discharging via the diode 177, the transistor 125, and the resistor 54 with a small discharge time constant.

T2 is the time during which capacitor 199 is gradually discharging only through resistor 54 with a large discharge time constant.

Here, the times T, -T and the time T2 are threshold voltages determined by the DC output of the bias up circuit 234 and the output of the waveform correction circuit 231.

When energization is started at an intersection point f between a portion where the slope of the AC output voltage A gradually changes in one direction and a portion where the threshold voltage gradually decreases, the threshold voltage is determined by the bias up circuit 234. voltage.

T3 is that time. The threshold voltage when the power supply voltage drops by charging the capacitor 199 to a constant value according to the power supply voltage is 8 in Fig. 4, the h point becomes the h/point, and the energization start point is f. Go from point to point g.

Therefore, the closing angle is enlarged. Here, when the engine speed is low, there is a gradual slope of the AC output voltage A of the AC generator 210, and a gradual slope according to the output of the waveform correction circuit 231 when the capacitor 199 is gradually discharging with a large time constant. The intersection point Lg with the threshold voltage that changes gradually is the starting point of current conduction, and the slope of this gradually changing part and the slope of the slowly changing part of the AC output voltage A are in opposite directions. Since it is inclined, the output of the waveform correction circuit 231 can correct sudden changes in the closing angle at low engine speeds and obtain good closing angle characteristics.

Furthermore, when the engine is at high speed as shown in FIG. 5, the same operation causes the energization start point to become k, and the closing angle is expanded.

As a result, the second closing angle characteristic with respect to the engine speed
Characteristics close to the ideal characteristics shown in Figure a can be obtained.

Furthermore, when the power transistor 154 is turned off at point e where the AC output voltage a sharply changes, the waveform correction circuit 231
The power transistor 154 should be further turned off (
Since a large bias is applied to the input transistor 106, even if ignition noise occurs when the power transistor 154 is off, that is, at the ignition timing, it is possible to prevent the input transistor 106 from malfunctioning due to the ignition noise.

As described above, in the present invention, the AC output from the AC generator that rotates in synchronization with the engine rotation is applied to the base circuit, and the power transistor is turned on and off in accordance with the on and off of the input transistor, and this power is The primary current of the ignition coil is intermittent depending on whether the transistor is on or off,
In addition, depending on whether the input transistor is on or off, the capacitor is charged to a certain value according to the battery voltage while the power transistor is on, and when the power transistor is off, the charge in the capacitor is gradually discharged. Bias according to the charging voltage of the capacitor,
A bias application circuit applies a voltage to the input transistor to promote turning off the power transistor, and a bias blocking circuit prevents a bias corresponding to the charging voltage of the capacitor from being applied to the input transistor while the capacitor is discharging. Furthermore, as the engine speed increases, a bias is applied to the input transistor by the closing angle expansion circuit in order to encourage the power transistor to turn on, and the bias applied to the input transistor by the bias application circuit is applied immediately after the power transistor is turned off. The structure is such that the bias gradually decreases from the maximum value to the maximum, and the slope of the gradually decreasing bias is in the opposite direction to the slope of the part where the alternating current output of the alternator changes gradually. By applying a gradually decreasing bias to the input transistor, it is possible to correct the closing angle, especially at low engine speeds, and obtain good closing angle characteristics. This bias is maximum immediately after the power transistor is turned off, so even if ignition noise occurs when the power transistor is turned off, that is, at the ignition timing, it is possible to prevent the input transistor from malfunctioning due to this ignition noise. There is an excellent effect that can be done.

[Brief explanation of drawings]

Figure 1 is a waveform diagram used to explain the operation of the conventional device.
The figure is a closing angle characteristic diagram of a conventional device, FIG. 3 is an electric circuit diagram showing an embodiment of the device of the present invention, FIGS. 4 and 5 are waveform diagrams for explaining the operation of the device of the present invention, and FIG. It is an output characteristic diagram of the bias up circuit 234 in the device of the present invention. 106... Input transistor, 109...
... Bias blocking transistor forming the bias blocking circuit, 126, 12... Bias applying transistor and bias resistor forming the bias applying circuit,
48-52, 54, 122-125, 166°176.
177... Resistor, transistor, Zener diode, diode, 154... that constitutes the charging/discharging circuit
...Power transistor, 199... Capacitor, 210... Alternator, 211...
...Battery, 212...Ignition coil.

Claims (1)

[Scope of Claims] 1. Rotates in synchronization with the rotation of the internal combustion engine and generates an AC output having a portion where the slope changes gently in one direction and a portion where the slope changes steeply in the other direction. an input transistor through which an alternating current output from the alternating current generator is applied to a base circuit; on and the alternating current output of the alternator is on. a power transistor that turns off when the power changes sharply in one direction; an ignition coil in which the primary current is intermittent depending on whether the power transistor is turned on or off; and a capacitor;
Depending on whether the input transistor is on or off, the capacitor is charged to a certain value depending on the battery voltage while the power transistor is on, and when the power transistor is off, the charge on the capacitor is removed. a charging/discharging circuit for discharging the capacitor; a bias applying circuit for applying a bias according to the charging voltage of the capacitor to the input transistor to encourage turning off the power transistor; and the capacitor is charged by the charging/discharging circuit. In between, a bias blocking circuit prevents a bias corresponding to the charging voltage of the capacitor from being applied to the input transistor, and a bias blocking circuit applies to the input transistor to encourage turning on of the power transistor as the engine speed increases. and a closing angle expansion circuit that applies a bias, and when the bias applied from the bias application circuit to the input transistor becomes maximum immediately after the power transistor is turned off and decreases as the power transistor is turned off, the same decreases to ζξ&4 test D. An ignition device for an internal combustion engine having a slope opposite to the slope of the part where the AC output of the alternator gradually changes. 2. The input transistor and the power transistor are connected to turn on and off in the same phase, and the bias application circuit includes a piero resistor connected between the emitter of the input transistor and the negative electrode side of the battery, this bias resistor, and A collector-emitter path is connected between the connection point of the emitter of the input transistor and the positive electrode side of the battery; and a bias applying transistor that applies a voltage proportional to the charging voltage of the capacitor to the bias resistor. The bias blocking circuit includes a bias blocking transistor that is connected in parallel with the bias resistor and turns on and off in the same phase as the input transistor depending on whether the input transistor is turned on or off. An ignition device for an internal combustion engine according to claim 1, characterized in that: 3. The charging/discharging circuit has a small discharging time constant when the charging voltage of the capacitor is high, and a discharging time constant that becomes large when the charging voltage of the capacitor is low. Alternatively, the ignition device for an internal combustion engine according to item 2.