JP2593571Y2 - Liquid-filled magnetic compass - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-filled magnetic compass in which a magnetic needle or the like that senses terrestrial magnetism is housed in a case and a liquid is sealed in the case.

[0002]

2. Description of the Related Art A liquid-filled magnetic compass of this type is a magnetic compass that, for example, can be used in water by divers and the like. The case is configured such that the case is not easily deformed or damaged by water pressure. The liquid-filled magnetic compass is disclosed, for example, in Japanese Utility Model Laid-Open No. 57-17412.

FIG. 7 is a sectional view showing an example of a schematic configuration of a conventional liquid-filled magnetic compass. Referring to FIG. 1, a conventional liquid-filled magnetic compass 1 includes a magnetic needle 5 that rotates by sensing geomagnetism, a shaft 6 that rotatably supports the magnetic needle 5, and a case that houses the shaft 6 and the magnetic needle 5. 2 and a liquid 8 sealed in the case 2. The shaft 6 is supported by the needle stand 7 in the case 2. Needle stand 7 contains liquid 8
Are provided with holes 10 through which can be freely circulated. The case 2 includes a main body case 3 and a bottom plate 4. The main body case 3 has a cylindrical shape, and has a transparent portion 9 on one end side in the axial direction of the cylinder so that the inside of the case 2 can be visually recognized from the outside. The bottom plate 4 is formed by bonding to the other end of the cylinder in the axial direction, and seals the liquid in the case 2.

Next, the above-described conventional liquid-filled magnetic compass 1
An example of a method for manufacturing the device will be described. First, the bottom plate 4, the magnetic needle 5, the shaft portion 6, and the needle stand plate 7 are formed in the main body case 2, respectively, to obtain an intermediate assembly. In this state, the liquid 8 is not yet sealed, and one small hole having a diameter of about 0.4 mm is formed in the side wall of the main body case 2. After this,
The intermediate assembly is placed in a liquid tank filled with liquid 8 with the small holes facing the liquid surface. The intermediate assembly is fixed to the bottom of the liquid tank by a jig so that the intermediate assembly does not float on the liquid surface due to the air in the case 2. Thereafter, the liquid tank is put into the defoaming device as it is, and when the air is evacuated by the vacuum pump, the air is exhausted from the small hole of the case 2 and the air pressure is returned to normal pressure, so that the inside of the case 2 is filled with the liquid 8. The intermediate assembly filled with the liquid 8 is taken out of the liquid tank, the small hole is filled with an adhesive, or a plug is screwed in, and the intermediate assembly is completed as the liquid-filled magnetic compass 1.

[0005]

However, for example, when the above-mentioned conventional liquid-filled magnetic compass 1 is exposed to a high temperature, the case 2 having plasticity is deformed due to expansion of the liquid 8. Then, when the liquid 8 shrinks due to a decrease in temperature, a void is formed in the case 2 and air bubbles are generated in the case 2, or air bubbles are generated in the case 2 due to deformation of the case 2. The movement of the magnetic needle 5 was sometimes hindered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid-filled magnetic compass that can prevent the generation of air bubbles in a case and can always keep a stable movement of a magnetic needle.

[0007]

The gist of the present invention for solving the above-mentioned problems is as follows: a magnetic needle which rotates by sensing geomagnetism;
A shaft portion rotatably supporting the magnetic needle, a case accommodating the shaft portion and the magnetic needle, and a liquid sealed in the case, wherein the case is transparent for visually recognizing the inside of the case from outside. And at least a portion of the case is a flexible liquid-filled magnetic compass.

[0008]

Even if the liquid expands due to a high temperature, or if the temperature decreases again and contracts, the flexible portion of the case bends due to the expansion and contraction. Is not possible, and even if it bends once, it returns to its original state if the temperature fluctuates. Therefore, no air bubbles are generated due to voids in the case or deformation of the case.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a first embodiment of the present invention. 6 are the same as those of the conventional liquid-filled magnetic compass 1 described with reference to FIG.
Description is omitted. The liquid-filled magnetic compass 1 in this embodiment includes a flexible film (diaphragm) 11 instead of the bottom plate 4. The fixing ring 12 on the ring is fixed to the inside of the main body case 3 by caulking, fastening, bonding or press-fitting, so that the needle stand plate 7 is locked by the locking portion 17 in which the inner wall of the main body case 3 is cut out. The flexible membrane 11 is fixed at its end 13 between the needle stand 7 and the fixing ring 12 to enclose the liquid 8.

FIGS. 2 to 5 are sectional views showing an example of a schematic configuration of a liquid-filled magnetic compass according to the second, third, fourth, and fifth embodiments of the present invention. 2, 3, 4, and 5, members denoted by the same reference numerals as those in FIG. 1 are the same as those in the liquid-filled magnetic compass 1 according to the first embodiment, and thus description thereof will be omitted.

Referring to FIG. 2, a liquid-filled magnetic compass 1 according to a second embodiment has a fixing ring 14 fixed to the outside of the main body case 3 by caulking, fastening, bonding or press fitting. The fixing ring 14 includes a locking piece 15 extending toward the center axis of the cylindrical shape of the main body case 3 in the radial direction, and the flexible membrane (diaphragm) 11 has a locking piece at its end 13. 15 is fixed between the main body case 3 and the liquid case 8.

Referring to FIG. 3, the liquid-filled magnetic compass 1 according to the third embodiment is swaged, fastened, adhered, or press-fitted to the outside of the main body case 3 by the fixing ring 16 to be used. Flexible film (diaphragm) 11
Is fixed between the locking piece 15 and the outside of the main body case 3 at the end portion 13 and seals the liquid 8.

Referring to FIG. 4, in a liquid-filled magnetic compass 1 according to a fourth embodiment, a fixing ring 18 on a ring is crimped inside the main body case 3 and fixed by fastening, bonding or press-fitting. Thus, the flexible film (diaphragm) 11 is locked at its end 13 by the locking portion 19 in which the inner wall of the main body case 3 is cut off, and is fixed between the fixing ring 18 and the locking portion 19. Is done.

Referring to FIG. 5, in a liquid-filled magnetic compass 1 according to a fifth embodiment, a retaining ring 20 is fixed to a notch 21 formed on the inner wall of the main body case 3, and a needle stand is attached to the retaining ring 20. The needle stand 7 and the main body case 3
An end portion 13 of a flexible film (diaphragm) 11 is sandwiched and fixed between an annular fixing ring 22 fixed by caulking, fastening, bonding, or press-fitting inside the inside.

The magnetic needle according to the present invention may be configured to have a circular plate-like portion on the surface of which a sign indicating an orientation, a scale, or the like is displayed, or both ends may be formed with an N pole and an S pole, respectively. The present invention can be implemented with magnetic needles having various structures, such as a magnetic bar needle.

Next, the operation of this embodiment will be described.
Liquid-filled magnetic compass 1 according to first to fifth embodiments
In this case, even if the liquid 8 expands due to a high temperature, and the temperature again decreases and shrinks, the flexible film 11 of the case 2
Since the flexure is caused by the expansion and contraction, no gap is formed in the case 2, and even if it flexes once, it returns to the original state if the temperature changes. Therefore, no air bubbles are generated due to voids in the case 2 or deformation of the case 2.

Next, an example of a method for manufacturing the liquid-filled magnetic compass 1 according to this embodiment will be described. FIG. 6 is a diagram for explaining the manufacturing method. First, the magnetic needle 5, the shaft portion 6, and the needle stand 7 are formed in the main body case 2 (the stop ring 2 in the liquid-filled magnetic compass 1 according to the fifth embodiment).
0 is also formed. ), The intermediate assembly 50. In this state, the flexible film 11 and the fixing ring 12 (or 14, 16, 18, 22) have not been formed yet.
The intermediate assembly 50 is placed in a liquid tank 51 filled with the liquid 8 as shown in FIG. At this time, the transparent part 9 of the intermediate assembly 50 is placed on the bottom side of the liquid tank 51. As shown in FIG. 6B, when the liquid tank 51 is put in the defoaming device 52 and degassed by the vacuum pump 53, not only air bubbles in the main body case 3 can be sufficiently removed but also the liquid 8 is saturated. Gas and volatile components such as air dissolved therein can be removed by evaporation. Thereafter, the defoaming device 52 is returned to normal pressure, and the liquid tank 51 is taken out of the defoaming device 52.
As shown in FIG. 6C, a flexible membrane 11 is fixed to a fixing ring 12 (or 14, 16, 1) in a liquid tank 51.
8, 22). After that, if you take it out of the liquid tank 51,
A liquid 8 is sealed in the intermediate assembly 50, and the flexible membrane 11 and the fixing ring 12 (or 14, 16, 1
8, 22) are also attached to complete the liquid-filled magnetic compass 1 according to the present embodiment.

[0018]

According to the above-described liquid-filled magnetic compass of the present invention, as described above, no air bubbles are generated due to voids in the case or deformation of the case. Therefore, it is possible to provide a liquid-filled magnetic compass that prevents generation of air bubbles in the case and that can always ensure stable movement of the magnetic needle.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a second embodiment, which is one embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a third embodiment, which is one embodiment of the present invention.

FIG. 4 is a sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing an example of a schematic configuration of a liquid-filled magnetic compass according to a fifth embodiment which is an embodiment of the present invention.

FIG. 6 is a diagram illustrating an example of a method of manufacturing the liquid-filled magnetic compass according to the embodiment.

FIG. 7 is a cross-sectional view illustrating an example of a schematic configuration of a conventional liquid-filled magnetic compass.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid-filled magnetic compass 3 Main body case 5 Magnetic needle 6 Shaft part 8 Liquid 11 Flexible film 12 Fixing ring

Claims (1)

(57) [Scope of request for utility model registration] 1. A magnetic needle that senses geomagnetism and rotates, a shaft that rotatably supports the magnetic needle, a case accommodating the shaft and the magnetic needle, and a liquid sealed in the case. A liquid-filled magnetic compass, wherein the case has a transparent portion for allowing the inside of the case to be visually recognized from the outside, and at least a part of the case has flexibility.