JP2542745Y2 - 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. 5 is an electric circuit diagram of the ignition device for the 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.

6 is a side sectional view of the ignition device for an internal combustion engine, FIG. 7 is a left side view of FIG. 6 before the case is filled with an insulating resin, 5 is a case, and 7 is inside 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 detecting section 3, the current detecting section 3 detects the value as a potential difference, and a control signal is sent to the current limiting circuit section 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, when the power transistor 1 and the current limiting circuit unit 4 are bonded to the heat sink 9 via the insulating plate 10, the power transistor 1 and the current limiting circuit unit 4 are attached. It is an electronic component, and special attention must be paid to the bonding work.
In order to prevent the destruction of the current limiting circuit 4, their surfaces must be covered with resin 11,
14 had to be provided, which hindered miniaturization.

The present invention has been made in order to solve such a problem, and it is an object of the present invention to provide an ignition device for an internal combustion engine that can improve the productivity and reduce the size, and suppress the influence of heat on a power switch from an ignition coil. Aim.

[Means for solving the problem]

In the ignition device for an internal combustion engine according to the present invention, an IC package body in which a power switch is formed by transfer molding a thermosetting resin in a case containing an ignition coil is disposed, and the IC package body is ignited. It is arranged on the wall surface side of the case away from the coil.

[Action]

In this invention, since the power switch is solid-sealed, handling during manufacturing is easy, and the IC package together with the ignition coil can be arranged in a case filled with insulating resin. Also IC
By arranging the package body on the wall surface side of the case away from the ignition coil, the power switch is not significantly affected by heat from the ignition coil.

〔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. 9 is a left side view before the case is filled with an insulating resin, and the same or corresponding parts as those in FIGS.

In the figure, reference numeral 30 denotes an IC package disposed in the case 31 at a position away from the ignition coil and on the wall side.The IC package 30 and the ignition coil are filled with the insulating resin 15 in the case 31. It is fixed at the same time. I c
The package body 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 30 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 IC package body 30 is disposed on the wall surface side of the case 31 away from the ignition coil, the power switch is not significantly affected by heat from the ignition coil.

Furthermore, the case 31 and the connector 12 are integrally
Since the space of the connector 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 using the control signal line 20, and the fourth connector terminal 24 and limiting circuit terminal of current limiting circuit 4
25 and the collector terminal 27 of the power transistor 1 can be easily connected to the other end of the primary coil 2 using the collector wire 26.

FIG. 3 is a side sectional view showing another embodiment of the present invention, and FIG.
FIG. 3 is a left side view before the case is filled with the insulating resin in FIG. 3. Reference numeral 40 denotes a heat radiating plate disposed in the case 31 for efficiently releasing heat generated by the power switch.
The IC package 30 is bonded to 40. The IC package 30 and the heat sink 40 are press-fitted into the case 31 and fixed.

[Effects of the Invention] As described above, according to the ignition device for an internal combustion engine of the invention, a power switch including a power transistor and a current limiting circuit for controlling a primary current is provided in a case containing an ignition coil. By arranging the IC package body which is solid-sealed by transfer molding with a thermosetting resin, the handling during the manufacturing process in which the IC package body can be handled as a single item is facilitated, and the productivity is improved. Further, the IC package can be arranged together with the ignition coil in the case filled with the insulating resin, so that the conventional power switch space is unnecessary, and the entire device can be downsized. In addition, by disposing the IC package on the wall side of the case away from the ignition coil, the power switch is not affected by the heat from the ignition coil in the same case, and the power switch malfunctions due to heat Also, for example, the power transistor and the current limiting circuit can be placed on the mounting base at the same time, and can be packaged by electrical connection and immediate transfer molding. In addition, a highly reliable product can be manufactured, and even if the characteristic variation after the combination occurs due to the characteristic variation of the power transistor and the current limiting circuit portion, it is instantaneous within the fully automatic line. In addition, the characteristics can be made uniform by, for example, laser trimming. 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, the reliability of preventing the power transistor from being destroyed is reduced. Since it is housed in the IC package, unnecessary resistance and inductance components can be eliminated, and 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 linear expansion coefficient. 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.
It is possible to use a highly reliable resin that is optimal for each purpose, thereby improving the reliability of the device. Further, the thermosetting resin has a lower coefficient of linear expansion than the thermoplastic resin and can prevent the power transistor from being damaged by the heat shock cycle. In addition, since transfer molding can be performed at a lower pressure than a molding method such as injection molding, 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 present invention, FIG. 2 is a left side view of the case shown in FIG. 1 before an insulating resin is filled, and FIG. 3 is another embodiment of the present invention. Side sectional view showing an example,
FIG. 4 is a left side view before the insulating resin is filled in the case of FIG. 3, FIG. 5 is an electric circuit diagram of an ignition device for an internal combustion engine,
FIG. 6 is a side sectional view of a conventional ignition device for an internal combustion engine, and FIG. 7 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, 30 is an IC package, and 31 is a case. 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 ignition device for an internal combustion engine in which an ignition coil is integrated with a power switch including a power transistor for continuously energizing a primary current of an ignition coil and a current limiting circuit for controlling the primary current. In the case containing the coil, an IC package body in which the power switch is transfer-molded with a thermosetting resin is provided, and the IC package body is provided on a wall surface side of the case away from the ignition coil. An ignition device for an internal combustion engine, comprising: