JPS5918550B2 - Non-contact ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact ignition device for an internal combustion engine, and in particular detects the output of a pickup coil and the output of the pickup coil in order to appropriately control the energization duty to the primary winding. The present invention relates to bias control of an ignition device equipped with a bias circuit for shortening the energization duty and a bias circuit for increasing the energization duty, which control a relative detection level with a waveform shaping circuit that forms an ignition pulse.

In this type of ignition device, the output of the pickup coil is an AC voltage, so if the reference ignition position is set when the output is at zero position, the ignition will start when the relative detection level moves to the side that shortens the energization duty. If the ignition timing advances, and conversely moves to the side where the energization duty is increased, the ignition timing will be delayed.

The bias for reducing the energization duty acts when the engine rotates at low speed, while the bias for increasing the energization duty generally acts when the engine rotates at high speed.

The advance characteristic of the ignition timing is generally set so that when the engine speed is low, ignition occurs at a relatively small advance position, and as the engine speed increases, ignition occurs at a gradually large advance position.

2. Therefore, the variation in ignition timing due to the control of the energization duty has a characteristic opposite to the normal ignition timing advance characteristic, resulting in a decrease in engine output and incomplete combustion of the fuel.

An object of the present invention is to prevent fluctuations in ignition timing peculiar to bias control type current conduction duty control over a wide range from low speed range to high speed range without impairing the bias control type current conduction duty control function.

In the present invention, the bias for shortening the energization duty is
This can be achieved by removing the bias in synchronization with the energization of the switching element, applying it in synchronization with the energization of the switching element, and removing the bias for increasing the energization duty only for a predetermined time before and after the ignition position.

An embodiment of the present invention shown in the drawings will be explained in detail below.

First, the basic configuration of the ignition device of this embodiment will be explained with reference to the block diagram shown in FIG.

Comparison circuit A functions as a waveform shaping circuit that compares the output of pickup coil B with a predetermined detection level and shapes it into a rectangular wave.

The output of pickup coil B is an alternating voltage (the waveform of which is shown in FIG. 3a) synchronized with the rotation of the engine.

In the basic bias supply circuit C, when the output of the pickup coil B is at zero level, the output of the comparison circuit A is the ignition coil 210.
In order to set a relative detection level between the output of the comparison circuit A and the output of the pickup coil B, the reference input of the comparison circuit is set to the output of the pickup coil B so as to generate an output to cut off the current flowing to the primary winding of the pickup coil B. A basic bias is supplied to at least one of the outputs.

The rotation speed-voltage conversion circuit consists of a small-capacity pump-up capacitor that charges and discharges in a relatively short period of time for each ignition cycle, and a relatively large-capacity integrating capacitor that stores a charge equal to the charge charged in the pop-up capacitor. A voltage proportional to the rotational speed is generated in the integrating capacitor.

The bias level variation circuit E applies a bias voltage corresponding to the output of the rotation speed-voltage conversion circuit, that is, the terminal voltage of the integrating capacitor, to the output of the pickup coil, and the comparison circuit A
and the output of the pickup coil.

As a result, the relative detection level changes as the energization duty to the primary winding of the ignition coil 210 (
The energization time to the primary winding/period X100 [%]) changes in the direction of increasing.

The amplifier circuit (2) amplifies the rectangular wave output from the comparison circuit A and supplies a base current to the power transistor 200 as a switching means.

The current limiting circuit J generates an output when the current flowing through the current detection resistors 160 to 163 connected to the circuit of the ignition coil 210 exceeds a predetermined value, and acts on the amplifier circuit 2 to supply base current to the Hower transistor 200. The power transistor 200 is suppressed to be in a non-saturated state, and the primary winding current is limited so as not to exceed a predetermined value.

The non-saturation time detection circuit F detects the time during which the power transistor 200 is in the non-saturation state, and the non-saturation time-voltage conversion circuit G converts it into a voltage.

The comparison voltage bias level variation circuit H controls the relative detection level between the outputs of the comparison circuit A and the pickup coil B in a direction that shortens the energization duty according to the voltage.

This reduces the current limit time of the power transistor 200, resulting in the minimum energization time required to obtain the necessary ignition energy for the ignition coil.

The ignition correction circuit outputs an output from the time when the output voltage of the pickup coil B exceeds a predetermined value until the power transistor switches from the energized state to the de-energized state, and outputs an energizing duty signal that is supplied to the bias level variation circuit E. The bias is changed in a direction to cancel the increasing bias, and the relative detection level between the outputs of the comparison circuit A and the pickup coil B is controlled to the detection level determined by the basic bias.

As a result, no matter how large the bias for increasing the energization duty is, ignition always occurs at the reference ignition position.

The noise killer circuit operates for a predetermined time from the time when the power transistor is switched from the energized state to the de-energized state, and the first
Then, the bias is changed in a direction to cancel the energization duty increasing bias supplied to the bias level changing circuit E, and the relative detection level is changed in the opposite direction to the changing direction of the output voltage of the pickup coil.

As a result, even if there is ignition noise superimposed on the pickup coil B during this period, it is possible to prevent the power transistor which is currently cut off from becoming conductive.

Although not shown in FIG. 1, the bias for shortening the energization duty supplied to the comparison voltage bias level variation circuit H is removed in synchronization with the start of energization of the power transistor 200, as will be described later.
It is configured so that the bias is reapplied in synchronization with the interruption of 0. As a result, while the noise killer circuit is in operation, the relative detection level changes further than the detection level determined by the basic bias. It fluctuates in the opposite direction, picking up more ignition noise and making it more unpleasant.

This shows that the detection level by the noise killer circuit can be controlled in the same direction as the detection level given by the duty reduction bias, which is further than the detection level determined by the basic bias.

Furthermore, although the noise killer circuit is not shown in FIG. 1, as will be described later, it has a circuit that shorts both ends of the pickup coil B, and this circuit is activated while the bias control is being performed. Both ends of the pickup coil B are short-circuited to prevent the ignition circuit from malfunctioning even if large ignition noise that cannot be removed by bias control alone occurs.

The present embodiment will be explained in detail below based on FIG.

In Figure 2, resistances 103, 104, 105°106
．． 107, 120, Zener diode 61, NPN)
Transistors 2, 3, diodes 41, 42, 43, PN
A basic bias supply circuit consisting of a P transistor 80, a pickup coil 180 that generates positive and negative AC voltages in synchronization with engine rotation, and resistors 108, 109, 110, 1.
By applying a varying current to 11, the pickup coil 18
A bias level variation circuit that varies the bias level of 0, a comparison voltage bias level variation circuit that applies a varying current to the resistor 112 through the diode 54, and varies the comparison voltage level of the comparison circuit, NPN) Ranjistalo, 7
,8. PNP) Comparison circuit consisting of Ranjistaff 5, 76.77, Zener diode 62, and resistors 115, 116, 117, NPN) Ranjistaff 9, 10, 13, 15.
Current amplification circuit consisting of PNP transistors 79, 81, resistors 121.125°128.119, 122, 130, Zener diode 59, NPN) transistor 32,
33,14, resistance 152,153°154.155,1
56, a diode 58, and an ignition coil 2 flowing through a power transistor 200 consisting of a PNP transistor 91.
10 primary current control circuit, NPN) transistor 26,2
7,28°29.30,31. PNP) transistor 88
゜89.90, Zener diode 68, resistor 157.
126, 147, 148, 149° 150.151 non-saturation time detection circuit for power transistor 200;
capacitor 173°PNP) transistor 87.78,
Diode 54゜55.56, 57, resistance 146, 14
5,144°143.118. NPN) transistor 24
．． 25, a non-saturation time-voltage conversion circuit consisting of capacitors 171, 172. NPN) transistor 20°21.2
2, diodes 51, 52, 53, resistance 137.138
, 139, 140, 141° 142, rotation speed-voltage conversion circuit consisting of Zener diode 67, NPN) transistor 16, 17° 19.22, 1. Diode 44,4
5,46°47.48,49,50. PNP) Langistav 1.73, 84, 85, resistance 101, 102°12
4. Landing point position correction circuit consisting of 133, 134, 135, NPN) transistors 22, 4, 5° 18. 19, 1.
PNP) Langistav 2.73°74, resistance 101,
Noise killer circuit consisting of 113, 114, 102, N
PN transistor 11゜12, PNP) transistor 82
, 83, a constant current supply circuit consisting of resistors 123 and 127,
Resistor 132, Zener diode 63, 64, 65°6
Abnormal voltage detection circuit consisting of 6, Zener diode 19
0, a protection circuit for a power transistor 200 consisting of a capacitor 174 and a resistor 131, an ignition coil 210 that generates high voltage, and a spark plug 220.

At the terminal A of the pickup coil 180, a positive and negative AC voltage as shown in FIG. 3a is generated with respect to the terminal B.
o,'+i1, current is supplied to the base of the NPN transistor.

One end B of the pickup coil 180 is connected to the anode of the diode 42 through the resistor 108, and the diode 42 is maintained at a constant voltage through the Zener diode 61, the resistor 104, the transistor 2, and the resistors 106 and 107.

The base of the transistor 70 on the reference side of the comparison circuit is the resistor 11.
2 to the midpoint of resistors 106 and 107, and is biased to a constant voltage when the engine is stopped.

When the engine rotates and a positive voltage is generated on the side of point A of the pickup coil 180, and the base voltage of the NPN transistor T becomes higher than the base voltage of the NPN transistor T, a current flows through the PNP transistor 75 and the PNP transistor 76° 77 is 0FFLNPN) Transistor 9 is OF"F"t,, NPN) Transistor 10 is ONL, N
PN) The transistors 13 and 15 are turned off, the power transistor 200 is turned on, and the primary current flows through the ignition coil 210.

At the point when the voltage generated on the side of point A of the pickup coil 180 suddenly changes from positive to negative, when it becomes lower than the base voltage of the NPN) transistor, the NPN transistor 7 becomes conductive, and the NPN transistor 7 becomes conductive. .77 is conductive, transistor 9 is ONL
,) transistor 10 is 0FFL, transistor 13.1
5 is ONL, and the power transistor 200 is 0FFL.

A high voltage is generated at the secondary terminal of the ignition coil 210), causing a spark discharge at the ignition plug 220.

When transistor 9 turns off, PNP) transistor 80
, the current force determined by the resistor 120 ζNPN) is supplied to the base of the transistor 3, the transistor 3 is turned on, and the resistor 10
6,107 is reduced by several tens of mV, the base voltage of the reference voltage side transistor 7 of the comparator circuit is lowered, the conduction state of the l-transistor is promoted, and the transistor 9 is turned on.
Then, NPN transistor 3 turns OFF”L, and resistor 1
The midpoint voltage of 06° 107 increases, promoting conduction of the NPN) Langistav.

When a primary current flows through the power transistor 200, a voltage responsive to the primary current is generated in the current detection resistor 161, and a resistance-divided voltage is generated at the midpoint between the current detection resistors 162 and 163.

A resistor 156 is located at the midpoint of the current detection resistors 162 and 163.
through which the emitter of NPN transistor 33 is connected and the collector is connected to the base of transistor 14,
The base of the transistor 33 is connected to the midpoint between the resistors 153 and 154, and the midpoint is a constant voltage obtained by dividing the voltage of the Zener diode 69 by the resistors 153 and 154.

The transistor 32 has an emitter follower configuration of the Zener diode 69, and the resistor 152 has a small resistance and is connected to prevent oscillation of the emitter follower.The midpoint voltage V of the resistors 153 and 154 has the following value. is set to .

However, VZ: Zener voltage of the Zener diode 69 VBE:) The base-emitter voltage of the transistor 32 and the forward voltage of the diode 58, that is, the midpoint voltage of the current detection resistors 162 and 163 increases, and the midpoint voltage of the resistors 153 and 154 increases. When the voltage becomes approximately equal to , the NPN transistor 33 changes from the ON state to the active state, supplies current to the base of the transistor 14, and the transistor 14 becomes conductive.

When transistor 14 becomes conductive, transistor 15 also becomes conductive, reducing the base current of power transistor 200 and making the power transistor non-saturated.

That is, by changing the power transistor 200 from a saturated state to a non-saturated state, the maximum value of the primary current is controlled to the set value.

The diode 58 is inserted for the purpose of canceling the temperature coefficient of VBE of the transistor 53, and the resistor 156 protects the transistor 33 when the midpoint potential of the current detection resistors 162 and 163 becomes negative due to a surge voltage. inserted for a purpose.

Further, by using the Darlington configuration for the transistors 14 and 15, the value of the resistor 155 can be increased, and when the control circuit is configured with a monolithic IC (hereinafter referred to as MIC), the power of the MIC can be greatly reduced.

In addition, the collector current of the PNP transistor 91 connected to the cathode of the Zener diode 690 is configured so that the same current flows as the collector current of the PNP transistor 83, which has a common base.Even when the power supply voltage is low, the Zener diode Since the Zener diode 69 is connected to the transistor 32 with an emitter follower configuration, the load impedance of the Zener diode 69 is very large.
Even at low voltage, the Zener voltage decreases little, so the midpoint voltage of resistors 153 and 154 decreases little even at low voltage, which has the effect of reducing fluctuations in the primary current limit value from low voltage to high voltage. .

On the other hand, when the power transistor changes from a saturated state to a non-saturated state and the collector voltage of the power transistor increases and becomes larger than the midpoint voltage of the resistors 148 and 149, the transistor 28 is connected to the collector of the power transistor through the resistor 157. Therefore, the transistor 28 becomes conductive.

NPN) The collector current of the transistor 29 is the resistor 150
, 127, is determined by the constant current configuration of the transistor 12, but increases somewhat as the power supply voltage rises, for example, about 100 μA at 12V and about 120 μA at 16V.

When the power transistor 200 is OFF, N
PN) Since the transistors 30 and 31 are ON, the transistor 28 is 0FFj, and when the power transistor 200 is conductive and non-saturated, the transistor 28 is conductive.

When transistor 28 conducts, PNP transistor 9
0 is conductive, and therefore PNP) transistors 87 and 88 are also conductive.

When transistor 88 becomes conductive, NPN) transistor 26
becomes conductive, lowering the midpoint voltage of the resistors 148 and 149, thereby stabilizing the conduction of the transistor 28.

PNP) The collector current of the transistor 87 is the resistor 146.
Since the collector current 75ζ of the transistor 90 has some voltage dependence, the collector current of the transistor 87 also has some voltage dependence.

When transistor 81 becomes conductive, charge is accumulated in capacitor 173.

That is, if the non-saturation time of the power transistor is long, the terminal voltage of the capacitor 173 becomes high for the same engine speed.

The terminal voltage of the capacitor 173 is determined by the emitter-follower configuration transistor 23, resistor 144, and diode 54.
When the terminal voltage of capacitor 173 is high, the base voltage of transistor 7 is also high.

However, at the time when the power transistor 200 is conductive, the terminal voltage of the capacitor 173 is not fed back to the base of the transistor 7 because the transistors 24 and 25 are ONt.

The purpose of this is 1. When the comparison voltage of the comparator circuit fluctuates while the power transistor 200 is turned on, that is, when the power supply voltage fluctuates at the same engine speed,
The comparison voltage also fluctuates - as a result, the timing for determining the ignition timing is to be prevented from fluctuating.

Due to the above operation, when the non-saturation time of the power transistor increases, the voltage at one terminal of the capacitor also increases, and the base voltage of the transistor 7 also increases1.As a result, the point at which transistor 6 starts conducting is delayed, and the power transistor 20
The conduction time of the power transistor 200 is shortened, and the non-saturation time of the power transistor 200 is shortened.

On the other hand, when the power supply voltage increases, the rising slope of the ignition coil secondary current increases, and the energization time for the primary current to reach a constant value also decreases.

As the time to reach a constant value decreases, the desaturation time of the power transistor also increases, resulting in the capacitor 173
The terminal voltage of will also increase.

On the other hand, since the voltage generated by the pickup coil does not vary depending on the power supply voltage, if the collector current of the PNP transistor 87 is completely constant against voltage fluctuations, the non-saturation time of the power transistor when the power supply voltage is 12V is Determine the circuit constants to be minimized, for example, for a 4-cylinder engine 60
When the power supply voltage is 5m5ec at 0rpm, the power supply voltage is 16
At V, it becomes about 10m5ec.

To have a value close to this, by slightly increasing the current value of the transistor 87 as the power supply voltage increases, the desaturation time of the power transistor will not differ by more than double whether the power supply voltage is 12V or 16V. I can do that.

Next, we will ask questions about the rotation speed/voltage conversion section, etc.

The AC voltage generated in the pickup coil 180 is an AC voltage with a positive/negative ratio of about 50, and unless some processing is done, the power transistor 200 will be turned on during high speed rotation.
Duty cannot be increased.

On the other hand, the peak value of the voltage generated by the pickup coil varies greatly even when the engine speed is the same, and a circuit that can output a stable duty even when such a pickup coil is used is required.

On the other hand, a characteristic of the pickup generated voltage is that even if the peak value varies by ±4040, the 80 coefficient of the waveform does not vary, so by adding a voltage generation circuit that is stable with respect to the rotation speed to the pickup coil generated voltage waveform. It is possible to output approximately 80% duty even during high speed rotation.

That is, when the transistor 13 is turned off, the resistor 128,
Current flows through the route of the diode 53, capacitor 172, resistor 141, diode 52, and capacitor 171, and the capacitor 171 accumulates charge for a period of time until the capacitor 172 is filled with charge, and the transistor 1
3 turns ON, the charge accumulated in the capacitor 172 is transferred to the diode 59, the resistor 141, and the capacitor 172.
, transistor 220 base-emitter, the root of transistor 13, diode 59, transistor 22 .
It is almost instantaneously discharged leaving 3VBE, which is the sum of 15 VBEs.

Since the capacitor 172 is discharged every cycle regardless of the rotation speed, the charging time of the capacitor 171 is almost constant with respect to rotation, and as a result, the terminal voltage of the capacitor 171 is a voltage that increases as the rotation speed increases. Become.

The terminal voltage of the capacitor 171 is determined by the resistor 139, the transistors 21, 20 . It is input to the base of the transistor 6 through a route of the resistor 137, the diode 51, and the resistor 111.

That is, even if the voltage generated on the side of point A of the pickup coil 180 becomes a negative voltage during high-speed rotation, the voltage accumulated in the capacitor 171 is applied through the above route, and the base voltage of the transistor 6 becomes lower than the base voltage of the transistor 7. becomes high, transistor 6 becomes conductive 1 power transistor 2
00 conducts, the ignition coil 210 is energized, and therefore a duty of about 80 parts can be obtained during high speed rotation.

The terminal voltage of the capacitor 171 becomes a voltage with little pulsation during high-speed rotation, so if it is constantly applied to the base of the transistor 6, the angle that determines the ignition position will be delayed as the rotation increases, and therefore the desired ignition position will be delayed. In the vicinity,
A configuration that can supply as many outputs as possible from the frequency-voltage conversion circuit is required.

Therefore, in this embodiment, the output of the frequency-voltage conversion circuit is not applied to the pickup coil 180 connection circuit as soon as the pickup coil generated voltage reaches an appropriate positive voltage. The supply to the circuit is configured such that it is restarted for a certain period of time after ignition.

That is, the midpoint voltage of the resistors 110 and 111 is the voltage at the diode 47.
, 48, 49, 50 and the transistor 17 (approximately 3V), the transistor 17 is turned ON and the transistor 16 is turned OFF. 19 is turned on so that the charge stored in the capacitor 171 does not flow into the base of the transistor 6, and the time point at which the ignition position is determined remains constant regardless of rotation.

Furthermore, after the transistor 13 is turned on, the transistor 22 used in the rotation speed-voltage conversion circuit is turned on by several hundred
By making the transistor 18 conductive and making the transistor 19 conductive during the conduction time of 1 tsec, the return of the accumulated charge in the capacitor 171 to the pickup coil side is delayed, and the chattering of the transistor 6 is prevented. Prevents accidental ignition.

That is, from the capacitor 171, the pickup coil 1
After an appropriate amount of time after the bias towards 80 is gone,
When transistor 6 becomes non-conductive, transistor 9 becomes conductive, and transistor 10 becomes conductive, the resistor 124,
Transistor 16 conducts through diode 44;
The current supply from the diode 45 to the transistor 19 disappears, but at the same time, the transistor 13 becomes ONL.
,,transistor 22 conducts and PNP transistor 7
3 is conductive, PNP transistor 1 is conductive, transistor 18 is conductive, and current is supplied to the base of transistor 19 through resistor 136 and PNP transistor 86. Even if transistor 16 is conductive, transistor 19 is It is conductive while transistor 22 is conductive.

On the other hand, when the spark plug 2200 is ignited, the transistor 15 is turned on.
After that, the power transistor 200
Cut 0FFt after c, then 40-50μsec
Later, the secondary voltage of the ignition coil becomes several tens of kilovolts and ignition occurs, so it takes 100 seconds after the transistor 6 of the comparison circuit to which the pickup coil 180 is connected becomes conductive.
Ignition is performed at μse break.

When ignition occurs at the spark plug 220, the pickup coil 1
80, the positive and negative noise voltages are several 10. It is superimposed for asec.

The voltage of the pickup coil at the time when this noise is on is heading towards the negative side, and the negative division of the noise,
Although the circuit is designed to stabilize the non-conduction of the transistor 6, the positive component of the noise is the amount that prevents the transistor 6 from becoming non-conductive, and it is necessary to remove this.

For this reason, the transistor 22 is activated several hundred μs after the transistor 6 becomes non-conductive and the transistor 13 becomes conductive.
The above noise is cut by making use of the conduction during ec, making the transistor 4 conductive during that time, and making the base voltage of the transistor 6 the same potential as the forward voltage (approximately 0.7 V) of the diode 42. .

That is, when the transistor 22 becomes conductive, the PNP transistor 73 becomes conductive, the transistor 72 becomes conductive, and the transistors 5 and 4 become conductive.

The above noise can also be cut when the emitter of transistor 4 is connected to the ground side, but in that case, in this configuration circuit, while transistor 4 is conducting, current flows through pickup coil 180, and transistor 4 OF
At the point F, the current in the pickup coil 180 suddenly decreases, and as a result, unnecessary voltage is generated at point A due to the inductance of the pickup coil, causing a phenomenon that makes the non-conduction of the transistor 6 unstable. Therefore, the emitter of transistor 4 is connected to pickup coil 180.
while transistor 4 is conducting,
This prevents direct current from flowing through the pickup coil 180.

On the other hand, if the battery connection terminal is disconnected while driving, a voltage of 120 to 140V may be applied to the power supply terminal, and if the power transistor 200 becomes conductive while such a voltage is generated, the power transistor 200 will instantly turn off. Destroy.

To prevent this, when the power supply voltage becomes abnormally high,
Zener diodes 63, 64, 65, and 66 conduct,
Transistor 15 is ONL, power transistor 20
0 is OFF.

The constant current circuit used in the amplifier circuit will be explained.

A reference current is set in advance using the resistor 127 and the transistor 12, and the collector current of the transistor 11 is set to a value smaller than the collector current of the transistor 12 depending on the value of the resistor 123. The fluctuation is smaller than the fluctuation in the collector current of the transistor 12.

A current of approximately the same value as the collector current of the transistor 11 flows through the PNP) transistor 83, and the collector current of the PNP) transistor 81 is determined by the value of the resistor 122.
less than the collector current of the P transistor 83, and
The current becomes more stable against voltage fluctuations.

The role of the PNP transistor 82 is inserted for the purpose of reducing the difference between the current flowing to the emitter and the current flowing to the collector of the PNP transistor 83.

This is the h of a PNP) transistor in a monolithic IC.
FE is very small and PNP transistor 86,7
4゜The base current of γ8, 79, 80, 81.91 is PN
P) By flowing directly to the collector of the transistor, it is possible to prevent the collector current of each transistor from not being designed smoothly.

As a constant current sink circuit using a pair of so-called NPN) transistors as described above, the transistor 1
2 and 11, 12 and 8, and 12 and 29, and the collector currents of transistors 11, 8, and 29 are currents that do not vary greatly with voltage fluctuations.

Also, as a constant current flow circuit using a pair of PNP transistors, PNP transistors 83 and 81, 83 and 80
．． 83 and 79.83 and 78°83 and 74.83 and 86.
83 and 91 and 90 and 88.90 and 87. and T3
There are 72, 73, 71, 75 and 16, and the operation is NP
This is the opposite of the constant current sink circuit using the N transistor 12.

When the constant current circuit has a monolithic IC (MIC) configuration, it has the effect of greatly reducing the area occupied by the internal elements of the MIC.

The waveforms of each part due to the above circuit operation will be explained using FIGS. 3 and 4.

At one end A of the pickup coil 180, a voltage as shown in FIG.
, 130 collector voltage is as shown in Figure 3, and the capacitor 17 is turned off at the timing when the transistor 13 is turned off.
1 is charged, the terminal voltage of capacitor 171 is
The result will be as shown in Figure 3C.

On the other hand, when the transistor 13 is OFF, the power transistor 200 becomes conductive, and the current flowing through the ignition coil increases as shown in FIG.
When the primary current reaches an appropriate value, the current control circuit operates and the primary current becomes a constant value.

At this time, the collector voltage of the power transistor is
It becomes a non-saturated state like this.

The collector voltage waveform of the transistor 30 that detects this non-saturation time is as shown in FIG. 3f, and the terminal voltage of the capacitor 173 of the non-saturation time-voltage conversion circuit is as shown in FIG. 3g.

FIG. 4g has the same waveform as FIG. 3g, and when the point voltage reaches an appropriate value, the transistor 17 becomes conductive.

The collector voltage waveform of transistor 17 is as shown in Figure 4, and the collector voltage of transistor 10 is as shown in Figure 4C.
As shown in FIG.
It will look like Figure d.

That is, the collector voltage of the transistor 19 becomes as shown in FIG. 4e, and as a result of these various movements, the base voltage waveform of the transistor 6 becomes as shown in FIG. 4f.

4g has the same waveform as FIG. 3g, but since the transistor 24 is ON during the period when the transistor 13 is OFF, the base voltage of the transistor 7 becomes as shown in the 4th diagram.

FIG. 5 shows the ignition coil energization time, ie, the duty characteristic, with respect to the distributor rotation.

The non-control curve in Figure 5 shows the characteristics when the output of the non-saturated time-voltage conversion circuit is not applied to the comparison voltage bias level variation circuit, and also shows that the duty decreases as the power supply voltage increases. This is because the time it takes for the primary current to reach a constant value decreases as the power supply voltage increases, and the non-saturation time also decreases.

FIG. 6 shows the ignition timing delay characteristics with respect to the distributor rotation speed.

The reason why there is a delay at an almost constant slope with respect to the increase in rotation is because the sum of the cut-off time of the power transistor mentioned above and the rise time of the secondary voltage of the ignition coil is about 100 μBec, and because there is an ignition position correction circuit. , the delay characteristic does not exceed that shown in FIG.

As explained above, according to the present invention, when the bias for shortening the energization duty exists, the relative detection level changes in a direction further away from the output voltage of the pickup coil at the same time as the energization starts. The output will not produce bunching.

Next, since ignition is performed with the energization duty increasing bias removed, ignition is always possible at the basic ignition position at any relative detection level, and there is no fluctuation in the ignition position over the entire rotation range.

Furthermore, the duty reduction bias returns to the normal bias at the same time as ignition, and the duty increase bias returns to the normal bias after a predetermined period of time after ignition, so where the duty reduction bias exists, the relative detection level immediately after ignition will be the detection level determined by the basic bias. It picks up more ignition noise and is transferred to the booster, making it more resistant to ignition noise.

Furthermore, in the presence of the duty shortening bias as described above, the relative detection level changes in a direction further away from the output voltage of the pickup coil immediately after ignition, so that the output of the waveform shaping circuit may cause tinging immediately after ignition. There is no.

In this way, the bias control type energization duty control function can prevent variations in the ignition timing over a fairly wide rotation range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a non-contact ignition device according to the present invention, FIG. 2 is a circuit diagram showing a specific embodiment of FIG. 1, and FIG. 3 is a waveform diagram of each part in FIG. Figure 4 is the second
FIG. 5 is a diagram of the rotation speed vs. duty characteristic of the IJ computer in the present invention, and FIG. 6 is a diagram of the rotation speed vs. ignition timing delay angle characteristic of the distributor in the present invention.

Claims (1)

[Claims] 1. A pickup coil that generates an alternating current voltage synchronized with the rotation of the engine, a waveform shaping circuit that shapes the output of this pickup coil into a rectangular wave, and an ignition coil that is energized according to the output of this waveform shaping circuit. a current control circuit that controls the maximum current value of the power transistor by making the power transistor non-saturated;
a first bias circuit that controls the relative detection level between the waveform shaping circuit and the output of the pickup coil in a direction that shortens the non-saturation time in accordance with the non-saturation time of the power transistor; A second bias circuit that controls the relative detection level between the waveform shaping circuit and the output of the pickup coil in a direction that increases the conduction period of the power transistor, the second bias circuit being activated during the conduction period of the power transistor and controlling the first bias circuit. a first bias removal circuit that removes the bias caused by the bias circuit; and a second bias removal circuit that removes the bias caused by the second bias circuit for a predetermined period before and after the time when the power transistor is cut off. A non-contact ignition device for internal combustion engines characterized by: 2. In the description set forth in claim 1, the waveform shaping circuit is constituted by a comparator circuit, and a reference terminal of the comparator circuit is provided with a basic bias and a bias for reducing the current conduction duty via the first bias circuit. A non-contact ignition device for an internal combustion engine, characterized in that a bias for increasing energization duty is supplied to an input terminal via an output of a pickup coil and the second bias circuit.