JPS6223108Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in preventing swinging of a mounting frame inside a housing of an electrical device.

In general, the housing of electrical equipment has a mounting frame attached to its upper case, built-in parts such as electrical parts are mounted to this mounting frame, and the exposed parts of the mounting frame and built-in parts are covered with a deep lower case. We try to secure the case by tightening it, but as the number of built-in components to be mounted on the mounting frame increases, it becomes necessary to make the mounting frame longer. The frame swung wildly and the mounting frame collided with the inner wall of the casing, and this collision caused secondary strong vibrations and shocks that could damage built-in components. Therefore, in this type of conventional device, it is necessary to reinforce the mounting frame and use built-in components that can withstand high vibrations and high shocks, resulting in high costs.

In view of these points, the present invention provides a housing for electrical equipment that eliminates the above-mentioned drawbacks by providing a vibration-proof fitting part between the metal frame and the lower case.

Hereinafter, embodiments of the present invention will be described based on the drawings. 1 and 2 show an embodiment of the present invention. In the figures, 1 is an upper case, 2 is a lower case, and a mounting frame 3 extending downward is attached to the inside of the upper case 1. Built-in components 4 such as resistors and capacitors are installed, and the mounting frame 3 is covered and protected by pulling up the lower case 2 from below and installing it. A circular convex portion 5 is provided at the center of the lower part of the mounting frame 3, and a circular concave portion 6 is provided at a position corresponding to the convex portion 5 on the inner side of the bottom of the lower case 2 and fits into the lower case mounting direction. will be established. The depth of this recess 6 is made somewhat deeper than the height of the convex part 5, and by making the upper part wide and the bottom part narrow in a mortar shape, the mounting frame 3 can be inserted smoothly. Tighten the upper and lower cases 1 and 2 as described above with screws 7. FIG. 3 is a sectional side view showing the main part of another embodiment of the present invention, in which the concave and convex portions 5 and 6 of the fitting portion are provided in reverse.

In the structure configured as described above, the mounting frame 3 is held by both the mounting portion of the upper case 1 and the concave-convex fitting portion of the lower case, and the free end portion of the mounting frame 3, that is, the lower portion thereof, is prevented from swinging in the horizontal direction. is suppressed by this uneven fitting part, so the mounting frame 3 swings abnormally due to external vibration impact and collides with the inner wall of the housing, causing 2
Next, strong vibrations and shocks can be generated to prevent damage to built-in components. Therefore, there is no need to increase the strength of the mounting frame 3 more than necessary, and there is no need to particularly increase the vibration resistance and impact strength of the built-in components.

Since the above-mentioned uneven fitting part has a cylindrical shape,
When attaching the lower case to the upper case, the fitting can be easily achieved by slightly moving it back and forth and left and right at the final stage of insertion. Of course, the shape of the concave-convex fitting part is not limited to a cylindrical shape, but may be polygonal or any other shape that regulates the fitting position so that the tightening positions of both the upper and lower cases can be aligned. The smaller the fitting tolerance of the uneven fitting portion, the greater the vibration prevention effect, but since the fitting portion is not visible from the outside, it will be difficult to fit if the tolerance is too small. Therefore, it is preferable to provide rounded or tapered corners at the entrance of the fitting part to facilitate insertion and to reduce the margin at the final stage toward the back. This tolerance is approximately 1 mm in diameter in the case of small electrical equipment.

Next, the effects of the configuration as described above will be explained.

The mounting frame supported by the upper case will be in the state of a cantilever beam (beam) if the fitting part of this invention is not provided, but if the fitting part is provided, it will become a fixed beam if the fitting is too tight. In a range where the joint is gentle, the beam becomes a double-end supported beam with one end fixed and the other freely supported. Also, it is assumed that the built-in components are uniformly installed on the mounting frame, and the load is assumed to be equally distributed. According to the Mechanical Engineering Handbook (Published by Japan Society of Mechanical Engineers, 1955 edition), the maximum deflection value δmax of a beam is δmax = βW ³ /EI where β is a constant determined by the type of beam;
Deflection coefficient W: Load, : Span of beam E: Elastic modulus of material I: Moment of inertia of area In this case, if W, E, and I are constant, the maximum deflection value δmax is proportional to the deflection coefficient β. The value of β is (a) β1/8 for a cantilever beam (b) β5/384 for a double-sided beam (c) β1/384 for a fixed beam (d) Double-sided beam with one side fixed and one side freely supported In the case of β = 1/184.6 Calculating from these values, when the same load is applied, the maximum deflection value for a fixed beam is 1/48 of that for a cantilever beam, and for the double beam in (d) above, the maximum deflection value is Even in this case, it will be 1/23rd. As mentioned above, since the fit between the mounting frame and the bottom of the lower case has a small tolerance, as the load increases, the fit becomes tighter and becomes a fixed burr state. In this case, since we are considering a case where a particularly large impact is applied, that is, a case where a large load is applied, it may be considered as a fixed burr. Therefore, according to the present invention, the maximum deflection value of the mounting frame is 48
This can prevent the mounting frame from swinging due to impact and colliding with the inner wall of the casing, thereby causing damage to built-in components.

As described above, the present invention is an electrical device in which built-in components are mounted on a mounting frame supported by an upper case, and these exposed parts are covered by pulling up the lower case from below to mount and cover the lower surface of the mounting frame and the lower case. Since a concave and convex engaging portion is provided between the bottom surface and the bottom surface to fit together in the mounting direction of the lower case, it is possible to obtain a housing for electrical equipment that is easy to assemble, is inexpensive, and is capable of shock-resistant protection of built-in components. be able to.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 show an embodiment of the present invention, Fig. 1 is a cross-sectional side view, Fig. 2 is a perspective view showing the main part, and Fig. 3 shows the main part of another embodiment of the invention. FIG. 1: Upper case, 2: Lower case, 3: Mounting frame, 5: Convex part, 6: Concave part.

Claims (1)

[Scope of utility model registration request] In electrical equipment in which built-in components are mounted on a mounting frame supported by an upper case, and the exposed parts of the mounting frame and built-in components are covered by pulling up the lower case from below, the lower surface of the mounting frame and the bottom surface of the lower case are A casing for an electrical device, characterized in that a concave-convex fitting part is provided between the parts to fit into each other in the mounting direction of the lower case.