JPS6248967A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make a device small and low cost and favorably increase an ignition energy by winding a primary auxiliary coil around the iron core of an ordinary ignition coil in the opposite direction to a primary coil, and adding an ignition energy increasing circuit. CONSTITUTION:When a primary current to an ignition coil 108 is cut off, a current flows in a primary auxiliary coil 209, and an energy due to electrification to the primary auxiliary coil 209 is added to an arc energy due to the cut off of the primary current. Since the turn ratio of the primary auxiliary coil and a secondary coil is larger than that of a primary and the secondary coils, a secondary voltage higher than a discharge supporting voltage for ignition plugs 3-6 can be obtained when the primary auxiliary coil is electrified. Also, it can be prevented that a current flows in the reverse direction in the primary auxiliary coil due to voltage induced in the primary auxiliary coil when the primary current is cut off, by means of a revere current preventing element diode 208, preventing the drop of a secondary voltage. Further, at the time of starting an engine, the effective number of turns of the primary auxiliary coil is reduced, to obtain a higher secondary voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an ignition system for an internal combustion engine, and more particularly to a high-energy ignition system.

[Conventional technology]

In recent years, various improvements have been made to ignition devices in order to achieve both reduction in fuel consumption and purification of exhaust gas in automobile engines, and high-energy ignition devices are essential for lean-burn engines in particular.

By the way, current interrupting type ignition devices are usually widely used as ignition devices for internal combustion engines. In this type of ignition device, the magnetic flux generated by the primary current of the ignition coil is stored in the iron core.
The spark energy is basically determined by the energy due to this stored magnetic flux. Therefore, in order to obtain more energy, it is necessary to increase the size of the iron core and the primary current or primary winding, which has the disadvantage of increasing the size of the device.

Also, devices that aim to increase the energy of normal ignition devices by using a DC-DC converter (for example, JP-A-55-9
No. 8671), or those using multiple ignition devices and adding up the secondary side of the coil (for example, U.S. Patent No. 3.2).
80.809) have been proposed, but they have the disadvantages of requiring expensive high-voltage diodes, preventing the device from increasing in size, and significantly increasing cost.

Furthermore, devices in which a capacitor discharge type ignition device and a normal current interrupt type ignition device are combined on the primary side (for example, FIGS. 4 and 6 of U.S. Pat. No. 3,280,809) have been proposed. However, it has the same drawbacks as the conventional example described above, such as an increase in the size and cost of the device.

On the other hand, a method has been proposed in which the spark energy is increased by using an ordinary ignition coil and alternately exciting the primary coil by turning on and off four power transistors (for example, Japanese Patent Laid-Open No. 7030/1989) Public bulletin). In this method, one pair of transistors is turned OFF to obtain the spark energy of a normal current interrupt type ignition device, and this energy is used to turn on the other pair of transistors to apply a voltage twice the turns ratio to the secondary side. The aim is to increase energy by generating and overlapping them.

[Problem that the invention seeks to solve]

However, this device requires two expensive PNP power transistors, two NPN power transistors, and two primary diodes, resulting in a high cost.

Further, in a normal ignition coil, the turn ratio between the primary coil and the secondary coil is approximately 100 times. This is because when the turns ratio is high (for example, around 200 times, that is, if the input energy on the primary side is constant, the number of turns in the primary coil cannot be changed)
, the number of turns in the secondary coil increases, resulting in high impedance of the secondary coil and poor leakage resistance characteristics, resulting in decreased performance when the spark plug smolders, and problems that occur in the secondary coil when the ignition coil is energized. This is because there is a possibility of ignition due to the voltage.

By the way, in a normal ignition system, the secondary high-voltage output of the ignition coil is connected to each spark plug via a distributor and a high-voltage cord containing a resistor. Here, the discharge sustaining voltage of each spark plug is about IKV, but voltage drops occur due to voltage being applied to high-voltage cords with resistors, distributors, etc., so the secondary output of the ignition coil is based on these voltage drops. Considering this, a discharge sustaining voltage of at least 2 KV or more is required. Furthermore, the discharge sustaining voltage of the spark plug varies depending on engine rotation and load. In addition, the engine battery voltage varies from V@=10 to 16 V depending on the rotation speed and load, so the superposition of the two
Affects the next output voltage. Therefore, JP-A-54-7030
When a normal ignition coil (turns ratio of about 100 times) is used as in the example in the publication, the secondary voltage generated when a pair of transistors conducts is about 12V x 100 = 1.2KV (adding energy with DT4 voltage). Considering that the discharge sustaining voltage of the secondary coil output is affected by the engine speed and load, and the secondary output voltage for superposition is affected by the power supply voltage. , In this type of stacked discharge type, the turns ratio of the ignition coil needs to be about 200 to 400 times. However, in order to make the normal ignition coil have such a high turns ratio, the coil impedance increases as mentioned above. There are problems with the high temperature and the possibility of sparks flying when the primary coil is energized.

The present invention solves the above problem, and aims to provide an inexpensive and compact high-energy single ignition device by adding a simple circuit to a conventional current interrupt type ignition device.

[Means for solving problems]

Therefore, the present invention provides an iron core, a primary wire wound around this iron core,
and a primary current intermittent means for intermittent primary current of the ignition coil, and generates a high voltage in the secondary coil when the primary current intermittent is interrupted by the primary current intermittent means. a current interrupting type ignition device; and a primary auxiliary, which is wound around the iron core so that the generated magnetic flux is in the opposite direction to the primary coil, and which has a smaller number of turns than the primary coil and has an intermediate tap in the middle of the winding. a coil; a primary auxiliary current intermittent means for forming an energization circuit for the primary auxiliary coil when the current of the primary coil is cut off; a backflow prevention element connected in series to prevent reverse current from flowing to the primary auxiliary coil; and a starting auxiliary circuit that switches to the intermediate tap to reduce the effective number of turns of the primary auxiliary coil when starting the internal combustion engine. An ignition device for an internal combustion engine is provided.

[Effect]

As a result, when the primary current of the ignition coil is cut off, a high voltage is induced in the secondary coil by the ignition energy previously stored in the iron core, which is discharged at the ignition plug and an arc current flows. Further, when the primary current is interrupted, a current flows through the primary auxiliary coil, and the arc energy due to the primary current interruption is added to the energy due to the energization of the primary auxiliary coil.

Here, since the number of turns of the primary auxiliary coil is smaller than the number of turns of the primary coil, the turns ratio of the primary auxiliary coil and the secondary coil becomes higher than the turns ratio of the primary and secondary coils, thereby increasing the , a secondary voltage higher than the discharge sustaining voltage of the spark plug is obtained when the primary auxiliary coil is energized. In addition, the reverse current prevention element prevents reverse current from flowing in the primary auxiliary coil due to the voltage induced in the primary auxiliary coil when the primary current is cut off. Prevents secondary voltage from dropping.

Further, when starting the internal combustion engine, the effective number of turns of the primary auxiliary coil is reduced by the starting auxiliary circuit to obtain a higher secondary voltage when the primary auxiliary coil is energized.

〔Example〕

The present invention will be explained below according to embodiments shown in the drawings.

1 is a battery whose negative terminal is grounded, 100 is a normal current interrupt type ignition device, and the secondary coil of the ignition coil 108 1) The high voltage output terminal of 1 is a high voltage cord 7a with a resistor.
7e and the distributor 2 to each spark plug 3.4, 5.6.

Next, a general current interrupt type ignition device 100 will be briefly described. The magnet big amplifier 101 that generates an AC output signal in synchronization with the rotation of the internal combustion engine is the igniter 1.
20, and this igniter 120 is connected to the AC output signal of the magnetic pickup 101.
It has a power transistor 107 which serves as a next current intermittent means.

Furthermore, the emitter of this power transistor 107 is grounded, and its collector is connected to the positive terminal 8 of the battery 1 via the primary coil 109 of the ignition coil 108.

200 is a spark energy increasing circuit, the details of which will be explained next. An inverter 210 is connected to the base side of the power transistor 107 of the igniter 120 and inverts the base signal of the power transistor 107. 2
20 is a monostable multi-bi break forming a monostable circuit, which can be configured using, for example, Toshiba's TC4047, and although a detailed explanation will be omitted, it outputs a high level with a width of about 2□ in synchronization with the rise of the output signal of the inverter 210. The output is connected to the base of a transistor 202 via a resistor 201. The emitter of this transistor 202 is grounded, and its collector is connected to the base of a transistor 204 via a resistor 203. This transistor 2
The emitter of 04 is connected to the positive terminal 8 of the battery 1, and its collector is connected to the two AND terminals of the starting auxiliary circuit 240.
connected to one input terminal of each of the circuits 234 and 235;
The output terminal of the ND circuit 234 is connected to the base of the power transistor 207 via the resistor 206. The emitter of this power transistor 207 is grounded, its collector is connected to the cathode of a diode 208, and the anode of the diode 20B is connected via a primary auxiliary coil 209 to the battery's positive terminal V! + is connected.

Here, the primary auxiliary coil 209 is wound on the iron core 1) 0 so that the magnetic flux is in the opposite direction to that of the primary coil 109, and the primary auxiliary coil 209 is wound on the iron core 1) 0 in the normal ignition coil 108. The turns ratio of 109 and secondary coil 1) 1 is 1
00 times, the primary auxiliary coil 209 and the secondary coil 1
) The turns ratio of 1 is approximately 200 to 400 times. In other words, the constant values of the primary coil 109 and the secondary coil 1)1 are the same as those of a normal ignition coil, and the primary coil 10
Primary auxiliary coil 209 with a number of turns of about 1/2 to 1/4 of 9
is added. Further, an intermediate tap 231 is provided in the middle of the winding of the primary auxiliary coil 209.

Next, the configuration of the starting assist circuit 240 portion will be described in detail. Reference numeral 8 denotes a starter inch, one end of which is connected to the positive terminal (2) of the battery 1, and the other end connected to the starter 9, as well as to the input terminal of the inverter 233 and the other input terminal of the AND circuit 235.
The output terminal of is connected to the other input terminal of the AND circuit 234. The output terminal of the AND circuit 235 is a resistor 236
The emitter of this power transistor 237 is grounded, and the collector is connected to the center tap 231 of the primary auxiliary coil 209 via a diode 238.

Next, the operation of the above configuration will be explained. The power transistor 107 becomes conductive in synchronization with the rotation of the engine, and current flows through the primary coil 109. Then, at a predetermined ignition timing, the power transistor 107 shuts off and the 1
Since the current in the secondary coil 109 is abruptly cut off, a high voltage is generated in the secondary coil 1) 1, and discharge occurs in the distributor 2 and each spark plug 3, 4, 5.6, causing an arc current to flow.

Up to this point, the operation is the same as that of a normal current interrupt type ignition system, but during normal operation when the starter switch 8 is open, the monostable multivib break 220 is activated for a predetermined period of time (approximately 2. 3)
A high level signal is output and the AND circuit 2
34 to conduct the power transistor 207 (
Here, the diode 208 is the power transistor 207
(This is to prevent backflow.)

By the way, the number of turns of the primary auxiliary coil 209 is about 1/2 to 1/4 of the number of turns of the primary coil 109, that is, the turns ratio between the primary auxiliary coil 209 and the secondary coil 1) is 200 to 40.
It is about 0 times. Furthermore, the direction of the magnetic flux generated in the iron core 1)0 by the current flowing through the primary auxiliary coil 209 when the power transistor 207 is conductive is different from the direction of the magnetic flux due to the current flowing through the primary coil 109 when the power transistor 107 is conductive. It is wound in the opposite direction. here,
In iron core 1) 0, the direction of the magnetic flux while the current in the primary coil 109 is flowing and the direction of the magnetic flux immediately after the current in the primary coil 109 is cut off are, as is generally known, opposite to each other. The direction of the magnetic flux after the current is cut off in the secondary coil 109 and the direction of the magnetic flux while the primary auxiliary coil 209 is energized are the same, and the arc energy due to the current cut off in the primary coil 109 is combined with the energy due to the energization in the primary auxiliary coil 209. It is possible to add them together.

As mentioned above, the discharge sustaining voltage of the spark plug is affected by the engine speed and load, and the secondary voltage caused by energization of the primary auxiliary coil 209 is also affected by the battery voltage. , primary auxiliary coil 209
The turns ratio between the primary coil 109 and the secondary coil 1) 1 is set to 200 to 400 times higher than the turns ratio (approximately 100 times) between the primary coil 109 and the secondary coil 1) 1. A high secondary voltage can also be obtained. Moreover, since the primary coil 109 and the secondary coil 1) 1 are the same as ordinary ignition coils, there are no problems such as an increase in coil impedance or sparks flying when energized.

The operation of this embodiment will be explained in more detail according to the operation waveforms of each part shown in FIG. The current flowing through the primary coil 109 ((a) in FIG. 2(2)), which starts energizing at time t0 due to the on/off of the power transistor 107 ((1) in FIG. 2), is at time 1.
．． It is blocked by As a result, a high voltage is generated in the secondary coil 1), which is discharged in the distributor 2 and each of the spark plugs 3 to 6, and an arc current [(b) in FIG. 2(5)] flows. At this time, the magnetic flux in the iron core 1) 0 [Fig. 2 (6)]
changes from xx to xl, and energy corresponding to the primary coil current is stored. Also, time 1. , a high-level output signal [Fig. 2 (3)] is generated in the monostable multi-bi break 220, and the primary auxiliary coil current [Fig. 2 (3)] is generated.
4)] flows, but this primary auxiliary coil current flows as shown in Figure 2 (
It is divided into (C) and tel in 4), and tel corresponds to (di) of the arc current in Fig. 2 (5). At this time,
The magnetic flux φ of iron core 1)0 changes from , x2 to X. Time t2 to t.

Between time t3 and time t4, the power transistor 107 conducts in the opposite direction, and the magnetic flux stored in the iron core 1)0 flows through the primary coil 109, causing the primary coil current to change ((2) in FIG. 2). After the reverse current corresponding to f) flows, it becomes zero.

Here, between times t2 and t3, the primary auxiliary coil current stores magnetic flux in the iron core 1)0 while reaching a predetermined current value (for example, the DC resistance value of the primary auxiliary coil 209: the same level as the primary coil 109, The primary coil current It is the time it takes to reach the current value set by the coil wire diameter.
is a predetermined value from time t0 to 1. Approximately 1/2 to 1/4 between
(The number of turns of the primary auxiliary coil 209 is 10
Since the number of turns is 1/2 to 1/4 of the number of turns of 9, its inductance is 1/4 to 1/16, and the rise time required to reach a specified current is 1/2 to 1/4 of that of the primary coil. As a result, the output pulse width of the monostable multi-bi break 220 (
1, to t3) is most efficiently set to the time (t+-ti) when the primary auxiliary coil current is only the current for storing magnetic flux.

In this embodiment, the iron core 1) of the normal ignition coil 108 is
The primary auxiliary coil 209, which has a number of turns of about 1/200 to I/400 of the primary coil, is simply wound in the opposite direction to the primary coil 109, and a power transistor 207, reverse current prevention diode 208, monostable multi-vibration break 220, etc. are added. It has an excellent feature of being able to approximately double the arc energy with an extremely simple circuit configuration.

In addition, even though the primary auxiliary coil 209 is about 1/2 to I/4 of the winding of the primary coil 109, the DC resistance value of the primary auxiliary coil 209 is lower than that of a coil with a small wire diameter. By using the current capacity of the power transistor 207 of the primary auxiliary coil 209, the current capacity of the power transistor 207 of the primary auxiliary coil 209 can be made almost the same as that of the primary coil 109.
The current capacity can be made the same as that of the power transistor 107 of No. 09.

Here, the primary coil 108, the secondary coil 109.
1) Describing a specific example of 1 and the primary auxiliary coil 209, the primary coil 109 has a wire diameter of 0.75 xx
Copper wire is wound 280 times, and its DC resistance is 48Ω.
The wire diameter is 0.06 as the secondary coil 1).
When the fin copper wire is wound 28,000 times, its DC resistance value is 13.
Using 5 KΩ, the primary and secondary coils 109, 1
) In the case of a normal ignition coil with a turns ratio of 100 times, use a copper wire with a wire diameter of 0.45 ml wound 93 times and a DC resistance of 1.48 Ω as the primary auxiliary coil 209. Therefore, the turns ratio of the primary auxiliary coil 209.secondary coil 1)1 is approximately 300 times.

Furthermore, when the starter switch 8 is closed to operate the starter 9 when starting the internal combustion engine, the power transistor 237 is made conductive via the AND circuit 235 by the output signal of a predetermined time width from the monostable multi-by-break 220, and the intermediate Primary auxiliary coil 2 via tap 231
Current is supplied only to some coil portions 230 of 09.

Here, by setting the turns ratio of this coil portion 230 and the secondary coil 1) 1 to about 600 times, even when the battery voltage is low at the time of starting the internal combustion engine, the coil portion 230 of the primary auxiliary coil 209 is 2 by energizing
The secondary voltage of the secondary coil 1) 1 can be made sufficiently higher than the discharge sustaining voltage of the spark plug, and the energy due to energization of the coil portion 230 of the primary auxiliary coil 209 is added to the arc energy due to the interruption of the primary current. It is possible to match.

In addition, in the embodiment described above, the starting assist circuit 240
In this case, starting of the internal combustion engine was determined by detecting the turning on of the starter switch 8. As shown in FIG. 3, the battery voltage is detected by the battery voltage detection circuit 250, and when the battery voltage drops below a predetermined value (for example, 8V for a 12V rated battery), it is determined that it is time to start the internal combustion engine, and the starting assist circuit 240 detects the battery voltage. may be activated.

Further, in the above-described embodiment, the primary auxiliary coil current is limited by the DC resistance value of the primary auxiliary coil 209, but it may be limited by controlling the power transistor 207 with a constant current.

Furthermore, in the embodiment described above, the monostable multipipe lake 220 has an output for a certain period of time, but
It is also possible to change the arc energy by arbitrarily varying this time depending on the engine speed, load, etc. Furthermore, the superimposition of the 7-arc energy by the spark energy increase circuit 200 reduces the consumption of the distributor 2 and spark plugs 3 to 6. In order to prevent this, it may be configured to operate only at low rotations and low loads.

[Effects of the Invention] As described above, in the present invention, the energy due to the energization of the primary auxiliary coil is added up when the primary current is cut off, and the number of turns of the primary auxiliary coil is smaller than the number of turns of the primary coil. The turns ratio between the primary auxiliary coil and the secondary coil is higher than the turns ratio between the primary and secondary coils, and when the primary auxiliary coil is energized, a secondary voltage higher than the discharge sustaining voltage of the spark plug can be obtained. Therefore, by adding a primary auxiliary coil with a smaller number of turns than the primary coil and a primary auxiliary current intermittent means for intermittent energization to this auxiliary coil to a normal current interrupting type ignition device, a simple circuit configuration is used. This has the excellent effect of being able to satisfactorily increase ignition energy while being inexpensive and compact.

Furthermore, when starting the internal combustion engine, the starting auxiliary circuit reduces the effective number of turns of the primary auxiliary coil and obtains a higher secondary voltage when the primary auxiliary coil is energized, so if the battery voltage is low when starting the internal combustion engine, Also, there is an excellent effect in that the arc energy caused by cutting off the primary current can be effectively added to the energy caused by energizing only a portion of the primary auxiliary coil.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing one embodiment of the device of the present invention, and FIG.
The figures are waveform diagrams of various parts for explaining the operation of the device shown in FIG. 1, and FIG. 3 is an electric circuit diagram showing the configuration of main parts of another embodiment of the device of the present invention. 8... Starter switch, 100... Current interrupting type ignition device, 107... Power transistor forming primary current intermittent means, 108... Ignition coil, 109... 1
Secondary coil, 1) 0... iron core, 1) 1... secondary coil. 207.220...Power transistor and monostable multivibrator constituting multi-order auxiliary current intermittent means, 208
...Diode 5209...1 forming a backflow prevention element
Next auxiliary coil, 231... Intermediate tap, 240...
Starting auxiliary circuit, 250... battery voltage detection circuit. Representative Patent Attorney Takashi Okabe Figure 2 Figure 3

Claims (3)

[Claims] (1) It includes an ignition coil having an iron core and primary and secondary coils wound around the iron core, and a primary current intermittent means for intermittent the primary current of this ignition coil, and the primary current intermittent means a current interrupt type ignition device that generates a high voltage in the secondary coil when the primary current is interrupted; a primary auxiliary coil with a smaller number of turns and an intermediate tap in the middle of the winding; a primary auxiliary current intermittent means for forming an energizing circuit for the primary auxiliary coil when current in the primary coil is cut off; a backflow prevention element that is connected in series with the primary auxiliary current intermittent means in the energizing circuit of the auxiliary coil and prevents reverse current from flowing to the primary auxiliary coil; An ignition device for an internal combustion engine, comprising: a starting auxiliary circuit that reduces the effective number of turns of the primary auxiliary coil. (2) The ignition device for an internal combustion engine according to claim 1, wherein the starting auxiliary circuit detects turning on of a starter switch to determine when to start the internal combustion engine. (3) The ignition device for an internal combustion engine according to claim 1, wherein the starting assist circuit detects a drop in battery voltage to determine when to start the internal combustion engine.