JP2002235650A - Ignitor for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignitor for an internal combustion engine preventing peeling-off and crack of a joining part of circuit elements by cold heat stress. SOLUTION: A circuit board 11 is guided by a rail 30 in a case 20 to be stored in the case 20. The rail 30 is formed into recessed/projecting shape having a plurality of projections 31 projecting to the side of the circuit board 11. The projection 31 is in contact with the external wall of the circuit board 11 so as to prevent the circuit board 11 from vertically rattling before filled with potting resin 40. When vibration is applied while injecting filler 50 inside the case 20 with an ignition circuit 10 stored therein, the circuit board 11 is preventing from shaking floating or inclining by the vibration and is stored in an original position. This constitution can reduce the stress acting on the circuit element of the ignitor circuit 10 from the potting resin 40 due to the temperature change to prevent the peeling-off and the crack of the joining part of the circuit elements by the cold stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine, and more particularly to an ignition device for an engine provided with an ignition circuit for interrupting a primary current of an ignition coil of an internal combustion engine (hereinafter referred to as an "internal combustion engine"). About.

[0002]

2. Description of the Related Art Generally, an ignition circuit of an engine ignition device is a circuit for interrupting a primary current of an ignition coil of an engine, and a circuit element is mounted on the ignition circuit for radiation of a circuit board and circuit elements. The molded circuit board is housed in a case, and a filling material such as a heat radiating material is charged into the case while applying vibration to achieve uniform filling, and then potting resin is injected for fixing and waterproofing. Is being used.

[0003]

However, in a conventional engine ignition device, for example, as shown in FIG.
When the circuit board 1 is accommodated in the case 2, the circuit board 1 is merely inserted along the rail 3 provided in the case 2. For this reason, when vibration is applied while the above-mentioned filling material is put into the case 2, the circuit board 1 dances due to the vibration, the filling material is sandwiched between the circuit board 1 and the case 2, and the circuit board 1 floats or tilts. May not fit in the original position. Here, since the engine ignition device is used in an environment where high and low temperatures are repeatedly applied, thermal stress is generated in the circuit board and the circuit element due to a difference in linear expansion coefficient between the circuit board and the circuit element and the potting resin. . As a result, when the circuit board is not in its original position in the case, a large stress acts on the circuit element of the mold ignition circuit from the potting resin due to a temperature change, and the stress causes a solder joint or wire bonding of the circuit element. The joints such as the parts are peeled off or cracked (crac
k) may occur, which may cause a failure of the ignition circuit.

Therefore, it is conceivable to apply a circuit element mounting adhesive on the circuit board or to attach an adhesive tape to the rail in the case and a part of the circuit board in close contact. However, in this case, there is a problem that extra work is required, the number of assembling steps is increased, and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an engine ignition device that prevents separation and cracking of a junction of circuit elements due to thermal stress.

Another object of the present invention is to provide an ignition device for an engine that prevents the circuit board from floating or tilting due to vibration. Still another object of the present invention is to provide an engine ignition device that can reduce the number of assembly steps and the manufacturing cost.

[0007]

According to a first aspect of the present invention, there is provided an ignition device for an engine. Is provided with an irregular portion that can be contacted with the outer wall of the circuit board. When vibration is applied while charging the filler into the case containing the ignition circuit, the convex portion of the guide portion contacts the outer wall of the circuit board. This prevents the circuit board from dancing due to the vibration, and prevents the circuit board from floating or tilting so that it does not fit in its original position. For this reason,
The stress acting on the circuit element of the ignition circuit from the potting resin due to the temperature change can be reduced, and peeling and cracking of the joint of the circuit element due to thermal stress can be prevented.

Further, extra work is required as compared with the case where the guide portion and a part of the circuit board are brought into close contact with each other by applying an adhesive for mounting a circuit element on the circuit board or attaching an adhesive tape to the circuit board. Instead, the number of assembly steps can be reduced and the manufacturing cost can be reduced.

According to a second aspect of the present invention, the engine ignition device is provided in a case accommodating the ignition circuit,
The circuit board side of the guide section that guides the circuit board is provided with a tapered surface that can contact the outer wall of the circuit board, so when vibration is applied while filling the inside of the case containing the ignition circuit Since the tapered surface of the guide portion comes into contact with the outer wall of the circuit board, the circuit board does not dance due to the vibration, and prevents the circuit board from floating or tilting to be out of its original position. Therefore, the stress acting on the circuit element of the ignition circuit from the potting resin due to the temperature change can be reduced, and peeling and cracking of the joint of the circuit element due to the thermal stress can be prevented. further,
No extra work is required compared to applying the adhesive for mounting the circuit element on the circuit board or sticking the adhesive tape to the guide part and a part of the circuit board,
The number of assembling steps can be reduced, and the manufacturing cost can be reduced.

According to a third aspect of the present invention, the engine ignition device is provided in a case accommodating the ignition circuit,
Since a protrusion that can contact the guide portion for guiding the circuit board is provided on the circuit board, when vibration is applied while charging the inside of the case containing the ignition circuit, the protrusion is moved by the guide portion. Therefore, the circuit board does not dance due to the vibration, and the circuit board is prevented from floating or tilting so that it does not fit in the original position. Therefore, the stress acting on the circuit element of the ignition circuit from the potting resin due to the temperature change can be reduced, and peeling and cracking of the joint of the circuit element due to the thermal stress can be prevented. Furthermore, no extra work is required compared to applying the adhesive for mounting the circuit element on the circuit board or attaching an adhesive tape to make the guide part and a part of the circuit board adhere to each other. The number of assembling steps can be reduced, and the manufacturing cost can be reduced.

According to the ignition device for an engine of the present invention, the projecting portion is a thick portion of the coating film applied on the circuit board. By forming a part of the circuit element to have a large thickness, peeling and cracking of a joint portion of the circuit element due to thermal stress can be easily and easily prevented. Therefore, the assembling work is facilitated, and the working time can be reduced.

According to the ignition device for an engine of the fifth aspect of the present invention, since the projecting portion is a thick portion or a wide portion formed on the circuit board, a part of the circuit board itself is made thicker or wider. By forming, it is possible to easily and easily prevent peeling or cracking of a joint portion of a circuit element due to thermal stress. Therefore, the assembling work is facilitated, and the working time can be reduced.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; (First Embodiment) FIG. 1 shows a main part of an engine ignition device according to a first embodiment of the present invention. In the engine ignition device of the first embodiment, an ignition circuit 10 for interrupting a primary current of an ignition coil (not shown) is housed in a case 20 formed of an insulating resin. The ignition circuit 10 incorporates a power transistor and a circuit element (not shown) such as an IC which constitutes an igniter for controlling on / off of the power transistor based on an ignition signal sent from an engine control computer (not shown). I have. The circuit element is mounted on a circuit board 11 such as a printed board and assembled.

A rail 30 is provided inside the case 20 as a guide for guiding the circuit board 11. The circuit board 11 is guided by the rail 30 so that the case 2
0. The rail 30 is formed in an uneven shape having a plurality of convex portions 31 protruding toward the circuit board 11 side. Since the protrusion 31 is in contact with the outer wall of the circuit board 11, the circuit board 11 does not rattle in the vertical direction in FIG. 1 before the potting resin 40 described later is filled. The inside of the case 20 is filled with a filling 50 such as a potting resin 40 and a heat radiating material, and the ignition circuit 10 is embedded in the inside of the potting resin 40. The potting resin 40 is made of an epoxy resin, a urethane resin, or the like, and the filler 50 exists substantially uniformly inside the potting resin 40 as shown in FIG.

In the first embodiment constructed as described above, when vibration is applied while charging the filler 50 into the case 20 containing the ignition circuit 10, the projection 31 of the rail 30 Is not in contact with the outer wall of the
To prevent it from floating or tilting so that it does not fit in its original position. Therefore, the stress acting on the circuit element of the ignition circuit 10 from the potting resin 40 due to the temperature change can be reduced, and peeling and cracking of the joint of the circuit element due to thermal stress can be prevented.

Further, extra work is required as compared with the case where the rail 30 and a part of the circuit board 11 are adhered to each other by applying a circuit element mounting adhesive on the circuit board 11 or attaching an adhesive tape. Is not required, the number of assembly steps can be reduced, and the manufacturing cost can be reduced.

(Second Embodiment) FIG. 2 shows a second embodiment.
The same components as those in the first embodiment shown in FIG. In the second embodiment, as shown in FIG.
The rail 60 has a tapered surface 61 formed on the circuit board 11 side. Since the tapered surface 61 is partially in contact with the outer wall of the circuit board 11, the circuit board 11 does not rattle in the vertical direction in FIG. 2 before the potting resin 40 is filled. Therefore, in the second embodiment, the same effect as in the first embodiment shown in FIG. 1 can be obtained.

(Third Embodiment) A third embodiment is shown in FIGS. The engine ignition device according to the third embodiment has an ignition circuit 7 for interrupting the primary current of an ignition coil (not shown).
0 is housed in a case 20 formed of an insulating resin. As shown in FIG. 4, the ignition circuit 70 includes a power transistor and a plurality of ICs or the like which constitute an igniter for controlling on / off of the power transistor based on an ignition signal sent from an engine control computer (not shown). The circuit element 73 of FIG. The circuit element 73 is mounted on a circuit board 71 such as a printed board, and is assembled. On the circuit board 71, a coating film 72 for protecting a circuit such as a green mask is applied, and a part of the coating film 72 is formed to be thick, and a protruding portion 72a as a thick portion is provided. I have. The protruding portion 72a can contact a rail 80 described later.

As shown in FIG. 3, a rail 80 is provided inside the case 20 as a guide for guiding the circuit board 71. The circuit board 71 is a rail 80
And is accommodated in the case 20. At this time, since the projection 72a of the ignition circuit 70 comes into contact with the rail 80, the circuit board 71 does not rattle in the vertical direction in FIG. 3 before the potting resin is filled.

In the third embodiment, the ignition circuit 70
When the vibration is applied to the inside of the case 20 in which the filler is charged, the protrusion 72 a of the ignition circuit 70 is in contact with the rail 80, so that the circuit board 71 does not dance due to the vibration. This prevents the 71 from floating or tilting so that it does not fit in its original position. Therefore, the ignition circuit 70 is removed from the potting resin due to a temperature change.
The stress acting on the circuit element 73 can be reduced, and peeling and cracking of the joint of the circuit element due to thermal stress can be prevented. In addition, extra work is required as compared with the case where the rail 80 and a part of the circuit board 71 are adhered to each other by applying a circuit element mounting adhesive on the circuit board 71 or attaching an adhesive tape. In addition, the number of assembly steps can be reduced and the manufacturing cost can be reduced.

(Fourth Embodiment) A fourth embodiment is shown in FIG.
In the engine ignition device of the fourth embodiment, an ignition circuit 90 for interrupting the primary current of an ignition coil (not shown) is housed in a case 20 formed of an insulating resin.

As shown in FIG. 5, an ignition circuit 90 comprises an IC which constitutes an igniter for controlling on / off of the power transistor based on a power transistor and an ignition signal sent from an engine control computer (not shown). And the like.
The circuit element 93 is mounted on a circuit board 91 such as a printed board, and is assembled. Circuit board 91
The projection 92 is formed to be partially wide to form a wide portion.
Is provided. The protruding portion 92 can contact a rail 80 described later. Inside the case 20, a rail 80 is provided as a guide portion for guiding the circuit board 91. The circuit board 91 is accommodated in the case 20 guided by the rail 80. At this time, the circuit board 91
The projecting portion 92 contacts the rail 80, so that the circuit board 91 does not rattle in the vertical direction in FIG. 5 before the potting resin is filled.

In the fourth embodiment, the ignition circuit 90
When vibration is applied while charging the filler into the inside of the case 20 containing the
Since it is in contact with 0, the circuit board 91 does not dance due to the vibration, and prevents the circuit board 91 from floating or tilting so that it does not fit in the original position. For this reason, the ignition circuit 90 is removed from the potting resin by a temperature change.
The stress acting on the circuit element 93 can be reduced, and peeling and cracking of the joint of the circuit element due to thermal stress can be prevented. In addition, extra work is required as compared with the case where the rail 80 and a part of the circuit board 91 are adhered to each other by applying a circuit element mounting adhesive on the circuit board 91 or attaching an adhesive tape. In addition, the number of assembly steps can be reduced and the manufacturing cost can be reduced.

In the fourth embodiment, the circuit board 91 is formed so as to be partially wide and the projection 92 is provided. However, in the present invention, the circuit board is formed so as to be partially thick. It is good also as a structure provided with a protrusion part. In this case, the same effect as in the fourth embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an engine ignition device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of an engine ignition device according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a main part of an engine ignition device according to a third embodiment of the present invention.

FIG. 4 is a view in the direction of arrows IV in FIG. 3;

FIG. 5 is a sectional view showing a main part of an engine ignition device according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a main part of an engine ignition device according to the related art.

[Explanation of symbols]

 10, 70, 90 Ignition circuit 11, 71, 91 Circuit board 20 Case 30, 60, 80 Rail (guide portion) 31 Convex portion 40 Potting resin 50 Filler 61 Tapered surface 72 Coating film 72a Projection portion 73, 93 Circuit element 92 Protrusion

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroo Ji 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Co., Ltd. (Reference) 3G019 KC05 KC08 KD05 KD06

Claims (5)

[Claims] An ignition circuit having a circuit board, a circuit element mounted on the circuit board, and intermittently intermitting a primary current of an ignition coil of an internal combustion engine; a case accommodating the ignition circuit; An ignition device for an internal combustion engine, comprising: a guide portion provided for guiding the circuit board; and an uneven portion provided on the circuit board side of the guide portion and capable of contacting an outer wall of the circuit board. . 2. An ignition circuit having a circuit board, and a circuit element mounted on the circuit board, for interrupting a primary current of an ignition coil of an internal combustion engine, a case accommodating the ignition circuit, and An ignition device for an internal combustion engine, comprising: a guide portion provided for guiding the circuit board; and a tapered surface provided on the circuit board side of the guide portion and capable of contacting an outer wall of the circuit board. . 3. An ignition circuit having a circuit board, and a circuit element mounted on the circuit board, for interrupting a primary current of an ignition coil of an internal combustion engine, a case accommodating the ignition circuit, and An ignition device for an internal combustion engine, comprising: a guide portion provided to guide the circuit board; and a projection provided to the circuit board and capable of contacting the guide portion. 4. The ignition device for an internal combustion engine according to claim 3, wherein the projecting portion is a thick portion of a coating film applied on the circuit board. 5. The device according to claim 3, wherein the projecting portion is a thick portion or a wide portion formed on the circuit board.
The ignition device for an internal combustion engine according to claim 1.