JP2008270288A - Case structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a case structure in which the whole case can be connected to the ground regardless of impairment of packing. <P>SOLUTION: A metallic case consisting of a body 2 for clamping a circuit board mounting an electronic component at both ends in the long side direction, and a pair of fixing plates 3 for clamping the circuit board at both ends in the short side direction is filled with filler composed of a resin material having heat dissipation properties such that at least some electronic components, especially those having high heating value, are buried. The body 2 and the fixing plate 3 are secured mutually by inserting a metal assembly screw 6 into fixing holes 2a and 3a penetrating the body 2 and the fixing plate 3 and then tightening the screw 6. A packing 5 composed of a resin material is provided between the body 2 and the fixing plate 3 in order to fill the gap between them, and a protrusion 30 abutting against the body 2 not through the packing 5 is provided on the periphery of the fixing hole 3a in the fixing plate 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a case structure used for heat dissipation of electronic components.

  Conventionally, a case structure is known in which a circuit board on which electronic components are mounted is housed in a case, and a resin filler is filled to dissipate heat generated from the electronic components, and the electronic components are embedded. For example, it is disclosed in Patent Document 1. In this type of case structure, in order to increase heat dissipation, it is common to use a metal case manufactured by a processing method such as sheet metal processing, die casting, or extrusion, but the cost required for the mold is high. Cases manufactured by extrusion molding are widely used because they require relatively little or have a high degree of freedom in designing the mold.

  Hereinafter, a conventional case structure using a case manufactured by extrusion will be described with reference to the drawings. In the following description, the top, bottom, left, and right in FIG. 3 are defined as the top, bottom, left, and right directions, the front side of the paper is defined as the front direction, and the back side of the paper is defined as the rear direction. In this conventional example, as shown in FIG. 3, a substantially rectangular circuit board 4 in which electronic components (not shown) are mounted in a metal case 1 is accommodated, and at least some of the electronic components are contained in the case 1. The case structure is filled with a filler (not shown) made of a resin material having a heat dissipation property so as to fill an electronic component having a particularly large calorific value.

  The case 1 is made of a metal material such as aluminum, for example, and includes a body 2 that sandwiches both side ends along the longitudinal direction of the circuit board 4 and a pair of both sides that sandwich the circuit board 4 along the short direction. It is composed of a fixed plate 3.

  The body 2 includes a substantially rectangular main plate 20 facing the circuit board 4 in the thickness direction of the circuit board 4 and a pair of side plates 21 extending upward from both side edges along the longitudinal direction of the main plate 20. A mounting groove 21 a having a width dimension substantially equal to the thickness dimension of the circuit board 4 is formed in the inner lower end portion of the side plate 21 over the longitudinal direction. Thus, by inserting and sliding any end portion of the circuit board 4 in the longitudinal direction into the mounting groove 21a from the front side or the rear side of the body 2, the circuit board 4 is moved in the short direction. It is clamped by the body 2 in a restricted form.

  On the outside of the side plate 21, a plurality of substantially rectangular parallelepiped fins 21 b are provided protruding in the longitudinal direction of the side plate 21 in order to improve heat dissipation. Further, left and right end portions on the front side and the rear side of the body 2 are each provided with a mounting hole 2a having a substantially circular shape with a quarter of a cross-section cut by a predetermined depth in the front-rear direction. A shaft portion of an assembly screw 6 described later is screwed into a female screw portion (not shown) provided on the inner peripheral surface of 2a.

  The fixing plate 3 is formed in a substantially rectangular shape with substantially the same dimensions as the front surface and the rear surface of the body 2, and substantially circular mounting holes 3 a are respectively provided in the front and rear direction at the lower left and right ends thereof. . Thus, the fixing plate 3 is brought into contact with the front end portion and the rear end portion of the body 2 and the metal assembly screws 6 are inserted into the mounting holes 2a and 3a and screwed together. While being fixed to the body 2, the circuit board 4 is sandwiched between the fixing plates 3 in such a manner that its movement in the longitudinal direction is restricted.

  A sheet-like packing 5 formed with a size slightly smaller than the fixed plate 3 is attached to the surface of the fixed plate 3 facing the body 2. The packing 5 is made of a resin material, and, as shown in FIG. 4A, is interposed between the body 2 and the fixing plate 3 to fill a gap generated between the body 2 and the fixing plate 3. The filler is prevented from leaking from the inside.

Here, the case 1 is generally used by being connected to the ground. In this case, the entire case 1, that is, both the body 2 and the fixing plate 3 need to be connected to the ground. In this conventional example, the body 2 and the fixing plate 3 are electrically connected via an assembly screw 6 that fixes the body 2 and the fixing plate 3 to each other, and a washer 6a that is inserted through the shaft portion of the assembly screw 6 and used. Connected. That is, as shown in FIG. 4A, the assembly screw 6 and the body 2 are electrically connected by screwing the shaft portion of the assembly screw 6 into the mounting hole 2 a of the body 2. By tightening the assembly screw 6 with the washer 6a inserted through the shaft, the head of the assembly screw 6 and the fixing plate 3 are electrically connected via the washer 6a. Thus, the entire case 1 can be connected to the ground.
JP 2005-129394 A

  However, in the above conventional example, the packing 5 is deteriorated by being pressed against the body 2 and the fixing plate 3 as time elapses, and as shown in FIG. Due to the shortening, a gap is generated between the fixed plate 3 and the washer 6a, and a situation may occur in which the washer 6a and the fixed plate 3 are not electrically connected. For this reason, there was a problem that the entire case could not be reliably connected to the ground, and the safety and noise performance were affected. Note that the above-described problem may occur even in a case structure in which a packing material is not filled as long as the packing 5 is interposed between the body 2 and the fixed plate 3 as in the conventional example.

  The present invention has been made in view of the above points, and an object thereof is to provide a case structure capable of connecting the entire case to the ground without depending on the deterioration of the packing.

  In order to achieve the above object, the invention of claim 1 includes a metal body having at least one end in the longitudinal direction opened, and a metal fixing plate that closes the opening surface of the body. A case structure in which a metal assembly screw is inserted into and screwed into a mounting hole extending through each of the mounting holes, and is fixed to each other. A packing made of a resin material is provided for filling the gap between the fixing plates, and the fixing plate is provided with a protrusion that abuts the body at least on the peripheral portion of the mounting hole without using the packing.

  According to the present invention, since the projecting portion that abuts the body without using the packing is provided at least on the peripheral portion of the mounting hole in the fixing plate, the thickness of the packing is reduced as the packing deteriorates over time. In this case, the body and the fixing plate can be brought into contact with each other through the protrusion. Therefore, since the body and the fixing plate are always electrically connected, the entire case can be connected to the ground regardless of the deterioration of the packing.

  Hereinafter, embodiments of a case structure according to the present invention will be described with reference to the drawings. However, since the basic configuration of the present embodiment is common to the conventional example, the same reference numerals are given to the same parts as the conventional example, and the description is omitted. In the present embodiment, as shown in FIG. 1A, a protrusion 30 that protrudes toward the body 2 is formed integrally with the fixing plate 3 on the peripheral portion of the mounting hole 3 a of the fixing plate 3. As shown in FIG. 2, the protrusion 30 has a shape that forms a part of a cylinder and covers about a quarter of the outer periphery of the mounting hole 3 a, and the thickness is the thickness of the packing 5. Are set to be approximately the same. Thus, when the fixing plate 3 is attached and fixed to the body 2, the tip of the protrusion 30 comes into contact with the front surface or the rear surface of the body 2. In order to bring the protrusion 30 into direct contact with the body 2, the packing 5 is formed with a substantially rectangular cutout 5a so as to avoid the peripheral portion of the attachment hole 3a and the protrusion 30 as shown in FIG. Has been.

  Further, as described above, the protrusion 30 does not cover the entire outer periphery of the mounting hole 3a, but covers a quarter of the outer periphery of the mounting hole 3a. The area of 5a can be made as small as possible, and leakage of the filler from the peripheral portion of the mounting hole 3a can be prevented.

  As described above, since the tip of the protrusion 30 of the fixing plate 3 is always in contact with the front surface or the rear surface of the body 2, the thickness of the packing 5 is deteriorated by the deterioration of the packing 5 over time. Even when becomes smaller, the body 2 and the fixing plate 3 can be brought into contact with each other through the protrusion 30 regardless of the thickness dimension of the packing 5 (see FIG. 1B). For this reason, since the body 2 and the fixing plate 3 are always electrically connected via the protrusion 30, the entire case 1 is always connected to the ground by connecting any part of the case 1 to the ground. be able to.

It is principal part sectional drawing which shows the case structure of embodiment of this invention, (a) is a figure which shows the state before packing deteriorates, (b) is a figure which shows the state after packing deteriorates. It is the schematic seen from the body side of a fixed board same as the above. It is a whole perspective view which shows the conventional case structure. It is principal part sectional drawing same as the above, (a) is a figure which shows the state before packing deteriorates, (b) is a figure which shows the state after packing deteriorates.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Body 20 Main plate 21 Side plate 3 Fixing plate 30 Protrusion 2a, 3a Mounting hole 4 Circuit board 5 Packing 6 Assembly screw

Claims (1)

  A metal body having an opening at least at one end in the longitudinal direction; and a metal fixing plate that closes the opening surface of the body. The body and the fixing plate are each made of a metal assembly screw in a mounting hole penetrating each other. Is a case structure that is fixed to each other by inserting and screwing, and a packing made of a resin material is provided between the body and the fixing plate to fill a gap between the body and the fixing plate, respectively. The fixing plate is provided with a protrusion that abuts on the body at least on the peripheral portion of the mounting hole without using a packing.

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