JPH0648943Y2 - Through cylinder - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a through-cylinder structure that ensures a breathing phenomenon in a case having a hermetically sealed structure such as equipment and prevents rainwater and the like from entering the case.

[Prior art]

If the case of a device is sealed for waterproofing, the atmospheric pressure inside the device will decrease due to continuous movement such as rotation and vibration of the device, heat generation of the device itself, heating from the outside such as sunlight, cooling by rainwater, ambient temperature Also, due to a change in atmospheric pressure and the like, a difference in atmospheric pressure occurs inside and outside the case, and if there is a portion with poor sealing performance in the case, humid air or water will enter from there and damage the equipment. As a measure to prevent this, in general, a ventilation cylinder that communicates with the outside air is provided at the lower end of the case, and air is allowed to flow in and out only through the cylinder so that water in the case due to dew condensation, etc. also naturally flows out through the ventilation cylinder. I have to. In the conventional example shown in FIG. 4, the through cylinder 12 attached to the lower end of the waterproof case 11 has a tube 12b fitted to the outer diameter of the fitting portion 12a with the case 11. In this structure, as shown by arrow A, water droplets are generated in the tube 12b.
There is a possibility that the tube 12b may collide with the inner wall of the body and jump back, or a water droplet may directly enter the case 11 as indicated by a broken arrow B. In order to prevent this, the tube 12b must be sufficiently long. , Becomes large. In another conventional example shown in FIG. 5, two shield plates 13a and 13b, which extend like a shelf, are provided on the inner wall of a through cylinder 13 attached to the lower end of a case 11 having a waterproof structure. The shield plates 13a and 13b shield the hole 13c of the through cylinder 13 by more than half. In this structure, even if water droplets fly in as shown by the arrow C, they are prevented from directly entering the inside of the case 11, but since a narrowed portion is formed in the hole 13c to increase the ventilation resistance, the through cylinder must be thickened. Instead, the through cylinder becomes large. Further, in order to integrally form the through-cylinder 13, either a stationary core is used or a rubber material is forcibly released due to the structure of the mold, so that the manufacturing cost is high.

[Means for solving problems]

The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and in a through cylinder that allows air to flow in and out provided in a lower end portion of a waterproof structure case in communication with outside air, a At least one of small protrusions, irregularities, continuous or discontinuous concave lines, or convex lines randomly arranged in a part or most of the inner wall of the through-cylinder pipe so as to prevent the repulsion of droplets colliding with the inner wall, or A group consisting of several kinds (hereinafter, simply referred to as a concavo-convex group) is provided. As a result, when droplets flying from the outside collide with the concavo-convex group on the inner wall of the through-cylinder, they are forced to undergo a complex deformation and deprived of kinetic energy to stop the repulsion or change the recoil angle downward. Thus, the droplets are prevented from entering the waterproof structure case.

【Example】

The present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which most of the inner wall 2b of the straight cylindrical through-cylinder 2 is formed with a group of concaves and convexes 2d consisting of a large number of recessed ridges 2c that go around the inner wall 2b at right angles to the axis of the through-cylinder 2. , (A) is a cross-sectional view of the through cylinder 2, and (B) shows a state in which the through cylinder 2 is attached to the motor case 1, which is a waterproof structure case. The fitting portion 2a of the through-cylinder 2 to the motor case 1 is composed of a cutout portion 1b provided in the lid portion 1a of the motor case 1 and a liquid-tight gasket 1d sandwiched between the lid portion 1a and the body portion 1c. It is fitted in the hole that allows it. Further, the through cylinder 2 has a bottom and an opening 2g to the outside on the lower side surface, so that the liquid droplets cannot enter the motor case 1 in a straight line. Each groove 2c is a surface 2f perpendicular to the axis of the through cylinder 2.
And downward face 2e. The droplets flying from the opening 2g collide with the concave-convex group 2d of the inner wall 2b to lose the kinetic energy to suppress the repulsion, and the downward surface 2e can change the recoil angle downward. FIG. 2 shows another embodiment, in which a large number of small projections 3c randomly arranged at the portion facing the outside of the inner wall 3b of the substantially L-shaped through cylinder 3 in which liquid drops cannot directly enter the waterproof structure case. A concavo-convex group 3b is formed, and a shielding plate 3h is provided to make the through cylinder 3 small. Each of the protrusions 3c is a cylinder that stands upright on the inner wall 3b. The droplets flying from the opening 3g collide with the uneven group 3d of the inner wall 3b to lose the kinetic energy to suppress the repulsion, and the recoil angle can be changed downward. FIG. 3 shows still another embodiment, in which the through-cylinder 4 is composed of a fitting part 4a to the waterproof structure case and a bellows part 4i, and the inner wall 4b of the through-cylinder 4 is formed from a large number of ridges 4c by the bellows part 4i. The uneven group 4d is formed. When used by being attached to the prevention structure case, the bellows portion 4i is bent and droplets cannot directly enter the waterproof structure case. Also in this case, the droplets flying from the opening 4g collide with the uneven group 4d of the inner wall 4b to lose the kinetic energy to suppress the repulsion, and the recoil angle can be changed downward. Although the three embodiments have been described above, the same effect can be obtained if the through-cylinder has any shape as long as the concavo-convex group is provided at an appropriate position on the inner wall. Further, even if the shielding plate is provided, only one is required, so that the mold structure is simple and the manufacturing cost is low.

[Effect of device]

The above-described through-cylinder according to the present invention is a through-cylinder that is provided at the lower end of the waterproof structure case and communicates with the outside air, and in which air flows in and out, drops of droplets that fly from the outside and collide with the inner wall of the through-cylinder. A group of at least one or several types of small projections, irregularities, continuous or discontinuous recesses, and projections, which are partially or mostly arranged at random on the inner wall of the through-cylinder pipe to prevent repulsion (hereinafter , Abbreviated as a concavo-convex group) is provided to prevent the repulsion of liquid droplets flying from the outside and colliding with the inner wall of the through cylinder, so that an excellent effect that a simple structure and a small size can be achieved is provided. is there.

[Brief description of drawings]

FIG. 1 is an embodiment of the present invention, (A) is a sectional view of a through cylinder,
(B) is a partial sectional view of the mounted state, FIGS. 2 and 3 are sectional views of another embodiment of the present invention, and FIGS. 4 and 5 are conventional examples. 1 is a waterproof structure case, 2, 3 and 4 are through cylinders, 2b, 3b and 4b are inner walls, 2c is a concave line, 3c is a convex part, 4c is a convex line, and 2d, 3d and 4d are concave and convex groups.

Claims (1)

[Scope of utility model registration request] 1. In a through-cylinder, which is provided at the lower end of a waterproof structure case and communicates with the outside air to let air in and out, the repulsion of liquid droplets flying from the outside and colliding with the inner wall of the through-cylinder is restrained. In addition, a part or most of the inner wall of the through cylinder pipe is provided with at least one kind or several kinds of small projections, irregularities, continuous or discontinuous concave lines, and convex lines arranged at random. Through cylinder.