JP2005349895A - Electric circuit device and tire air pressure monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve adhesion strength between a potting material and a case without changing a case resin material or radiating ultraviolet rays. <P>SOLUTION: In this electric circuit device, an electric circuit part 2 is accommodated inside a resin case 1, and the inside of a case 1 is filled with a potting material 3. Projections and recesses 11, 12 are provided on an inner wall of the case 1, and an adhesion area of the potting material 3 and the case 1 is increased, so as to improve adhesion strength between the potting material 3 and the case 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric circuit device in which an electric circuit portion in a resin case is sealed with a potting material, and is particularly suitable for a tire pressure monitoring device for a vehicle.

  The adhesive strength per unit area between the potting material and the resin case by potting is determined by the potting material to be used and the material of the case. In order to improve the adhesive strength between the potting material and the case, use a resin material that is compatible with the potting material as the case material, or irradiate the case with ultraviolet rays after molding the case, There is a method of performing potting in a state where the activity of the surface is increased.

  However, when selecting a case resin material that has good compatibility with the potting material in order to improve the adhesive strength as in the former case, depending on the selected resin material, the cost may increase, and the adhesiveness may be poor in terms of quality. Although improved, the physical properties of the material may have decreased strength and may be a negative factor such as reduced corrosivity.

  On the other hand, the method of irradiating the case with ultraviolet rays in order to improve the adhesive strength, as in the latter case, increases the cost because it requires ultraviolet irradiation equipment.

  In view of the above points, an object of the present invention is to improve the adhesive strength between a potting material and a case without changing the case resin material or performing ultraviolet irradiation.

  In order to achieve the above object, according to the first aspect of the present invention, the electric circuit portion (2) is accommodated in the resin case (1), and the potting material (3) is filled in the case (1). The electrical circuit device thus provided is characterized in that concave and convex portions (11, 12) are provided on the inner wall surface of the case (1).

  According to this, by providing the uneven portion on the inner wall surface of the case, the bonding area between the potting material and the case can be increased, and the bonding strength between the potting material and the case can be improved. That is, the adhesive strength between the potting material and the case can be improved without changing the case resin material or performing ultraviolet irradiation.

  Further, since the thermal resistance between the potting material and the case can be lowered due to the increase in the bonding area between the potting material and the case, an improvement in the heat radiation effect of the entire product can be expected.

  The invention according to claim 2 is characterized in that uneven portions (13, 14) are provided on the outer wall surface of the case (1).

  According to this, since the case surface area increases, the heat dissipation effect is enhanced. In addition, sinking during molding of the case can be prevented by setting the size and position of the uneven portions on the inner wall surface and the uneven portions on the outer wall surface so that the case thickness is uniform.

  In the invention according to claim 3, the transmitter is mounted on the tire of the vehicle, measures the air pressure in the tire and wirelessly transmits the air pressure data, and is installed on the vehicle main body side. In the tire pressure monitoring apparatus including a receiver for receiving, the receiver has an electric circuit portion (2) housed in a resin case (1), and a potting material (3) is placed in the case (1). It is filled, and the concave and convex portions (11, 12) are provided on the inner wall surface of the case (1).

  According to this, the adhesive strength between the potting material and the case can be improved, and an improvement in the heat dissipation effect can be expected. By the way, the receiver with built-in antenna of the tire pressure monitoring device generally has better reception performance when installed outside the vehicle compartment than when installed in the vehicle interior, and such a waterproof structure is required, and in some cases near the engine room depending on the radio wave reception state Since it has a heat generating element and has a heating element, it is likely to become high temperature, and a large heat radiation effect can be expected in such a receiver.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view of the electric circuit device according to the first embodiment, and FIG. 2 is a perspective view of the case alone of FIG.

  As shown in FIGS. 1 and 2, the electric circuit device includes a resin case 1 and an electric circuit portion 2 accommodated in the case 1.

  The case 1 has a bottomed rectangular tube shape in which only the upper part is opened, and a plurality of concave portions 11 and convex portions 12 are formed on the inner wall surface of the case 1. The case 1 is formed by a mold, and the concave and convex portions 11 and 12 extend in parallel to the drawing direction of the case 1 in order to make a low-cost mold. In addition, when the uneven | corrugated | grooved parts 11 and 12 cannot be put in parallel with the extraction direction of the case 1, the uneven | corrugated | grooved parts 11 and 12 are put in a slide core.

  In the electric circuit unit 2, a large number of electronic components 22 are mounted on a printed circuit board 21, and a wire harness 23 is connected to the printed circuit board 21. The electric circuit portion 2 is sealed with a potting material 3 filled in the case 1, and is fixed in the case 1 by adhesiveness between the case 1 and the potting material 3. In addition, as the potting material 3, a liquid silicone resin or a urethane resin can be used, for example.

  In this embodiment, since the uneven portions 11 and 12 are provided on the inner wall surface of the case 1, the bonding area between the potting material 3 and the case 1 is increased, and the bonding strength between the potting material 3 and the case 1 is improved.

  Moreover, the increase in the bonding area between the potting material 3 and the case 1 reduces the thermal resistance between the potting material 3 and the case 1, and an improvement in the heat dissipation effect of the entire product can also be expected.

Note that the electric circuit device according to the present embodiment can be applied to a tire pressure monitoring device. Incidentally, the tire pressure monitoring device includes a transmitter that wirelessly transmits air pressure data by measuring air pressure in the tire, and a receiver that receives air pressure data transmitted from the transmitter. The device is mounted on the vehicle tire, and the receiver is installed on the vehicle body side.
In general, a receiver with a built-in antenna of a tire pressure monitoring device has better reception performance when mounted outside the vehicle interior than when mounted inside the vehicle interior, and requires a waterproof structure when mounted outside the vehicle interior. Further, in some cases, the receiver is likely to become high temperature because it is installed near the engine room depending on the radio wave reception state and has a heating element. Therefore, it is desirable to apply the electric circuit device according to the present embodiment to a receiver.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 3 is a perspective view of a case alone in the electric circuit device according to the second embodiment. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 3, in the present embodiment, a large number of concave portions 13 and convex portions 14 are also formed on the outer wall surface of the case 1. The outer wall surface uneven portions 13, 14 extend in parallel to the removal direction of the case 1, similarly to the inner wall surface uneven portions 11, 12. Thus, since the surface area of the case 1 is increased by providing the outer wall surface uneven portions 13 and 14, the heat dissipation effect is further enhanced.

  Further, in order to prevent sink marks when the case 1 is molded, the size and position of the inner wall surface uneven portions 11 and 12 and the outer wall surface uneven portions 13 and 14 are set so that the thickness of the case 1 is uniform. Yes.

It is sectional drawing of the electric circuit apparatus which concerns on 1st Embodiment of this invention. It is a perspective view of the case single-piece | unit of FIG. It is a perspective view of a case simple substance in an electric circuit device concerning a 2nd embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Case, 2 ... Electric circuit part, 3 ... Potting material, 11 ... Concave part, 12 ... Convex part.

Claims (3)

In the electric circuit device in which the electric circuit portion (2) is accommodated in the resin case (1) and the potting material (3) is filled in the case (1), the inner wall surface of the case (1) An electrical circuit device characterized in that a concave and convex portion (11, 12) is provided on the surface. The electric circuit device according to claim 1, wherein uneven portions (13, 14) are provided on an outer wall surface of the case (1). A transmitter that is mounted on a tire of a vehicle and that measures air pressure in the tire and wirelessly transmits air pressure data, and a receiver that is installed on the vehicle body side and receives the air pressure data. In the tire pressure monitoring device,
In the receiver, the electric circuit portion (2) is accommodated in a resin case (1), the case (1) is filled with a potting material (3), and the case (1) A tire air pressure monitoring device, wherein the wall surface is provided with uneven portions (11, 12).

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