JP2542746Y2 - Ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ignition device for an internal combustion engine in which a power switch for intermittently supplying a primary current of an ignition coil and an ignition coil are integrated.

[Conventional technology]

FIG. 3 is an electric circuit diagram of the ignition device for an internal combustion engine.
Reference numeral 3 denotes a power transistor that cuts off the primary current through the primary coil 2 of the ignition coil, and 3 denotes a current detection unit that detects a potential difference caused by the primary current and transmits a signal for controlling the primary current to the current limiting circuit unit 4.

4 is a side sectional view of the ignition device for the internal combustion engine, FIG. 5 is a left side view of FIG. 4 before the case is filled with the disconnection resin, 5 is a case, and 7 is in the case 5. A secondary coil, which is provided and wound around an iron core 8 around the primary coil 2, 9 is an aluminum radiator attached to the case 5, and the radiator 9 is provided with power via an insulating plate 10. The transistor 1 and the current limiting circuit unit 4 are bonded. Reference numeral 11 denotes a silicone resin for coating and protecting the power transistor 1 and the current limiting circuit unit 4 to improve heat dissipation, 12 denotes a connector integrally molded with the case 5, and 13 denotes a power transistor 1 and a current limiting circuit. A cover for sealing the power switch space 14 to ensure waterproofness of the power switch composed of the portion 4, and 15 is an insulating resin filled in the case 5.

16 is a secondary coil ground wire connecting the first connector terminal 17 to one end of the secondary coil 7; 18 is a power supply wire connecting the second connector terminal 19 to one end of the primary coil 2; A control signal line connecting the third connector terminal 21 and the base terminal 22 of the power transistor 1, 23 is a ground line connecting the fourth connector terminal 24 and the limiting circuit terminal 25 of the current limiting circuit unit 4, and 26 is Collector terminal 27 of power transistor 1
The control signal line 20, the ground line 23 and the collector line 26 pass through the case 5 and are connected to the base terminal 22 and the limiting circuit terminal in the power switch space 14 through the collector line. 25 and the collector terminal 27, respectively.

In the above ignition device for an internal combustion engine, the primary coil 2
When the primary current flows through the current detection unit 3, the current detection unit 3 detects the value as a potential difference, and a control signal is sent to the current limiting circuit unit 4 based on the potential difference value. The current limiting circuit 4 controls the primary current flowing through the primary coil 2 of the ignition coil based on this signal. A high voltage is generated in the secondary coil 7 of the ignition according to the primary current flowing through the primary coil 2, and this high voltage is sent to the distributor.

[Problems to be solved by the invention]

In the ignition device for an internal combustion engine configured as described above, in order to minimize the leakage magnetic flux from the ignition coil, the magnetic permeability is very large, and the ferromagnetic core 8 is used. In addition, there is a problem that the power switch may malfunction.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an ignition device for an internal combustion engine that prevents a magnetic flux generated from an ignition coil from affecting a power switch.

[Means for solving the problem]

The igniter for an internal combustion engine according to the present invention is characterized in that a radiator plate for releasing heat generated from the power switch is provided in the power switch, in which a radiator plate is formed by transfer molding a thermosetting resin to the power switch. The heat sink is located between the ignition coil and the ignition coil, and the heat sink is made of a non-magnetic material having a small magnetic permeability.

[Action]

In this invention, the magnetic flux from the ignition coil to the power switch has low magnetic permeability and is blocked by a non-magnetic radiator plate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 2 is a side sectional view showing an embodiment of the present invention, and FIG.
FIG. 6 is a left side view before the case is filled with an insulating resin, and the same or corresponding parts as those in FIGS. 3 to 5 are denoted by the same reference numerals and description thereof is omitted.

In the figure, reference numeral 30 denotes a radiator plate having an L-shaped cross section made of aluminum, which is a nonmagnetic material and has a small magnetic permeability, which is disposed in a case 31 and a part of the radiator plate 30 is exposed to the outside air. It has a wavy shape, and the tip is connected to the iron core 8. Reference numeral 32 denotes an IC package bonded to the heat radiating plate 30. The IC package 32 and the heat radiating plate 30 are pressed into the case 31 and fixed. This IC package 30 is configured by solid-sealing the power transistor 1 and the current limiting circuit unit 4 with resin by transfer molding.

In the ignition device for an internal combustion engine configured as described above, the power switch including the power transistor 1 and the current limiting circuit unit 4 is solid-sealed, so that the power switch can be handled as a single item. And the productivity is improved.

In addition, by solid-sealing the power switch, the IC package 32 can be arranged together with the ignition coil in the case 31 filled with the insulating resin 15, and the conventional power switch space 14 becomes unnecessary. The entire device is downsized.

Further, since the case 31 and the connector 12 are integrated and the space of the case 31 and the space of the connector 12 communicate with each other, the third connector terminal 21 and the base terminal 22 of the power transistor 1 are connected to the control signal line 20. Connection between the fourth connector terminal 24 and the limiting circuit terminal 25 of the current limiting circuit unit 4 using the ground wire 23, and the collector terminal 27 of the power transistor 1 and the other end of the primary coil 2. It can be easily connected to the unit using the collector wire 26.

Furthermore, a part of the heat sink 30 is exposed to the outside air,
Heat generated from the power switch is efficiently released to the outside air through the heat radiating plate 30.

Further, since the heat sink 30 is connected to the iron core 8 attached to the engine and grounded, and is electrically stable,
The electric influence of the power switch attached to the heat sink 30 from the ignition coil is reduced.

Furthermore, the heat sink 30 is mounted on the power switch between the power switch and the ignition coil, and this heat sink 30 is made of non-magnetic aluminum with low magnetic permeability. All of the magnetic flux is blocked by the heat sink 30.

In the above embodiment, the heat radiating plate 30 made of aluminum has been described. However, the heat radiating plate is not limited to this, and the material of the heat radiating plate may be a non-magnetic material having a small magnetic permeability and a large thermal conductivity. For example, it may be copper.

[Effect of the invention]

As described above, according to the ignition device for an internal combustion engine of the present invention, the heat radiator is mounted on the power switch between the power switch and the ignition coil, and the heat radiator is attached to the non-magnetic material having a small magnetic permeability. Therefore, the magnetic flux from the ignition coil to the power switch is blocked by the heat radiating plate, and the malfunction due to the magnetic flux of the power switch is prevented.

In addition, the power switch is formed by transfer molding with a thermosetting resin and is integrated, so that the power switch can be handled as a single item, and the handling during manufacture is facilitated, and there is an effect that productivity is improved. In addition, for example, the power transistor and the current limiting circuit can be simultaneously arranged on the mounting base, respectively, and can be packaged by electrical connection and immediate transfer molding. Full automation enables short man-hours, short time, low cost, and high reliability In addition, even if amplification of the characteristic variation after the combination occurs due to the characteristic variation of the power transistor and the current limiting circuit unit, the characteristic can be instantaneously obtained by, for example, laser trimming in a fully automatic line. There is also an effect that uniformization becomes possible. In addition, the current limiting circuit unit detects, for example, a current flowing through the power transistor as a voltage of a detection resistor of the current detection unit, and prevents a current from flowing to the power transistor over a predetermined current to prevent the power transistor from being destroyed. If there is an unnecessary resistance component (wiring resistance, connection resistance) or inductance component between the transistor and the current limiting circuit unit, the reliability of the power transistor destruction prevention decreases, but the current limiting circuit unit and the power transistor Since it is housed in the IC package, unnecessary resistance and inductance components can be eliminated, and there is an effect that the reliability of the device is improved. In addition, a voltage-resistant resin is generally impregnated between coil windings that generate a high voltage, while the power transistor is sealed in a heat shock cycle when the linear expansion between the power transistor and the resin occurs. In order to prevent damage to the power transistor due to the stress generated due to the difference in the rate of expansion, it is necessary to select a resin with a low coefficient of linear expansion. And the like, and an increase in the amount of the reinforcing agent causes a decrease in impregnation. On the other hand, in the present invention, it is not necessary to use the same resin for sealing the transistor and impregnating the coil, so that it is possible to use a highly reliable resin that is optimal for each purpose, thereby improving the reliability of the device. There is also the effect of doing. Further, the thermosetting resin has an effect that the power transistor can be prevented from being damaged by the heat shock cycle at a lower linear expansion coefficient than the thermoplastic resin. In addition, transfer molding can be performed at a lower pressure than a molding method such as injection molding, so that there is an effect that the power transistor and the current limiting circuit are not damaged at the time of molding.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment of the invention, FIG. 2 is a left side view of the case shown in FIG. 1 before an insulating resin is filled, and FIG. FIG. 4 is a side sectional view of a conventional ignition device for an internal combustion engine, and FIG.
FIG. 4 is a left side view before the case is filled with an insulating resin. In the figure, 1 is a power transistor, 2 is a primary coil, 4 is a current limiting circuit, 7 is a secondary coil, 8 is an iron core,
Reference numeral 30 denotes a heat sink. In each drawing, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Scope of request for utility model registration] 1. An iron core and a primary coil wound around the iron core,
An ignition device for an internal combustion engine in which an ignition coil having a secondary coil and a power switch including a power transistor for intermittently supplying a primary current flowing through the primary coil and a current limiting circuit for controlling the primary current are integrated. In the power switch integrated by transfer molding with a thermosetting resin, a radiator plate for releasing heat generated from the power switch is mounted between the power switch and the ignition coil, and is attached to the power switch. An igniter for an internal combustion engine, wherein the heat sink is made of a non-magnetic material having a small magnetic permeability.