JP2014240731A - Fusible plug - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain normal stable operation of a fusible plug, even in a case of using a RoHS product.SOLUTION: In a fusible plug, a straight-shaped through hole 2e included in a body 2 is filled with a low melting metal 3 melting at a predetermined temperature, and mainly containing tin, bismuth, indium and the like and not containing lead and cadmium; and the pressure reception side of the through hole 2e is loaded with a conical plug member 4 having a peaked head shape peaking toward an open end side. It is suitable that the plug member 4 is a conical shape, a cut head conical shape, or a shell shape. The plug member is formed of a material having a melting point higher than the low melting metal 3.

Description

  The present invention relates to a fusible stopper used for a condenser, a liquid receiver, and the like that are at high temperature and high pressure in a refrigeration apparatus.

  The fusible stopper used in the above-mentioned application is composed of a through hole drilled in the main body and a low melting point metal filled in the through hole, and when reaching a predetermined temperature, the low melting point metal filled in the through hole Melts and discharges the internal refrigerant to the outside to prevent the refrigeration apparatus from being damaged.

  Conventionally, this fusible stopper has been made of low melting point metal (hereinafter referred to as “non-RoHS product”) mainly containing lead (Pb), cadmium (Cd), etc., but it has an adverse effect on the environment and the human body in EU member countries. As a result of the adoption of the RoHS Directive, which prohibits the use of hazardous substances that cause toxic substances, the launch of products using lead or cadmium in the same area has been completely prohibited. For this reason, the use of substances not containing lead, cadmium, etc. (hereinafter referred to as “RoHS products”) has been promoted.

  Therefore, Patent Document 1 describes a low melting point metal having excellent creep characteristics that does not contain any harmful substances such as cadmium and is filled with a solder alloy made of tin, bismuth, and indium in a through hole in a cylindrical body. A fusible stopper is proposed.

JP 2009-203501 A

  However, in the fusible stopper described in Patent Document 1 and the like, the RoHS product is likely to cause local strength reduction during use due to component segregation or defects such as internal voids, and has recently prevented the destruction of the ozone layer. Therefore, the inside of the refrigeration system may be at a high pressure by using carbon dioxide as a refrigerant instead of chlorofluorocarbon, and before the fusible plug operates, that is, the fusible plug operates normally. Before starting, the low melting point metal may be pushed out by the pressure in the refrigeration apparatus starting from the portion where the strength is reduced.

  Therefore, in view of the problems in the prior art described above, the present invention realizes stable operation without the low melting point metal being pushed out before the fusible stopper operates normally even when the RoHS product is used. An object is to provide a fusible stopper.

  In order to achieve the above object, the fusible plug of the present invention is a fusible plug formed by filling a straight through hole provided in a main body with a low melting point metal that melts at a predetermined temperature. A plug member having a pointed shape toward the open end is loaded on the pressure receiving side.

  According to the fusible plug of the present invention, by receiving pressure on the pressure receiving side using a plug member having a pointed shape, there is no influence of local strength reduction. Thereby, even when a RoHS product is used, it is possible to realize a normal and stable operation of the fusible stopper.

  In the fusible plug, the pointed shape of the plug member is preferably a conical shape, a truncated conical shape, or a bullet shape, and the plug member has a melting point higher than that of the low melting point metal. Formed of material.

  As described above, according to the present invention, it is possible to realize a stable operation of the fusible plug even when a RoHS product is used.

It is sectional drawing which shows 1st Embodiment of the soluble stopper which concerns on this invention. It is sectional drawing which shows 2nd Embodiment of the soluble stopper which concerns on this invention. It is sectional drawing which shows 3rd Embodiment of the soluble stopper which concerns on this invention.

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a first embodiment of a fusible plug according to the present invention. The fusible plug 1 is inserted into a straight through hole 2e provided in a cylindrical body 2 at a predetermined temperature. The melting low melting point metal 3 is filled, and the conical plug member 4 pointed toward the open end side is loaded on the pressure receiving side of the through hole 2e.

  The main body 2 is provided in an engaging portion 2a capable of engaging with a tool (not shown) such as a wrench for connecting to a pipe or the like, and a condenser or a liquid receiver present on the pressure receiving side of the fusible plug 1. A first male screw portion 2b for connecting to the formed female screw portion, a second male screw portion 2c for connecting to a female screw portion such as a pipe existing on the open end side, and an annular groove formed in the inner wall surface of the main body 2 2d and a through hole 2e.

  The annular groove 2d is formed on the inner wall surface of the main body 2, and by increasing the bonding area between the main body 2 and the low melting point metal 3, the bonding strength between the two is strengthened, the peeling of the low melting point metal 3 is prevented, and The low melting point metal 3 is prevented from jumping out vigorously when the pressure side pressure rises rapidly.

  The low melting point metal 3 is composed of tin (Sn), bismuth (Bi), indium (In), or the like, and uses a RoHS product that does not contain lead, cadmium, or the like.

  The conical plug member 4 is formed of a material having a melting point higher than that of the low melting point metal 3, and has a cylindrical base portion 4a and a conical pointed portion 4b that is pointed from the base portion 4a toward the open end side. The fit between the outer peripheral surface of the cylindrical base 4a and the inner peripheral surface of the through hole 2e of the main body 2 is set to such an extent that the conical plug member 4 can move smoothly through the through hole 2e.

  As the material of the conical plug member 4, any metal material or resin material can be used as long as it has a higher melting point than the low melting point metal 3. If it is a metal material, tin (Sn), aluminum (Al), copper (Cu), a copper alloy (brass), etc. can be used. If it is a resin material, Teflon (registered trademark), nylon or the like can be used.

  When the conical plug member 4 is loaded on the pressure receiving side of the through hole 2e of the main body 2, the plug member 4 is moved from the pressure receiving side of the through hole 2e before the low melting point metal 3 filled in the through hole 2e is solidified. Even if the low melting point metal 3 is pressed and brought into close contact with the low melting point metal 3 without any gap, and a local strength drop or void is generated inside the low melting point metal 3, the influence can be reduced.

  The fusible plug 1 having the above-described configuration can receive pressure on the pressure receiving side by the conical plug member 4 loaded on the pressure receiving side of the through hole 2e of the main body 2, and segregates components, internal voids, etc. on the low melting point metal 3 Thus, the low melting point metal 3 can be stably extruded without being affected by the defects. Thereby, the stable normal operation | movement of the soluble stopper 1 is realizable.

  FIG. 2 shows a second embodiment of the fusible plug according to the present invention. The fusible plug 5 uses a truncated conical plug member 6 instead of the conical plug member 4 in the first embodiment, and the other configuration is the same as that of the fusible plug 1.

  The truncated conical plug member 6 is formed of the same material as that of the first embodiment, and has a cylindrical base portion 6a and a truncated conical pointed portion 6b sharpened from the base portion 6a toward the open end side. The fitting method between the outer peripheral surface of the base 6a and the inner peripheral surface of the through hole 2e of the main body 2 and the method of loading the through hole 2e of the main body 2 are the same as those in the first embodiment, and the same effects are obtained. Play.

  FIG. 3 shows a third embodiment of the fusible plug according to the present invention. This fusible plug 7 uses a bullet-shaped plug member 8, and the other configuration is the same as that of the first embodiment.

  The bullet-shaped plug member 8 is formed of the same material as the plug member 4 of the first embodiment, and has a cylindrical base portion 8a and a bullet-shaped pointed head portion 8b that is pointed from the base portion 8a toward the open end side. The method of fitting the outer peripheral surface of the base 8a and the inner peripheral surface of the through hole 2e of the main body 2 and the method of loading the through hole 2e of the main body 2 is the same as in the case of the conical plug member 4, and the same effects are obtained. Play.

  Note that the shape of the plug member is not limited to a conical shape, a truncated conical shape, or a bullet shape, but may be other pointed shapes. Of course, the plug member may have a solid shape instead of a hollow shape. In the case of such a solid shape, the product is cut from a bar. The hollow plug members 4, 6, and 8 are press-worked products or molded products.

1, 5, 7 Fusible plug 2 Main body 2a Wrench engaging portion 2b First male screw portion 2c Second male screw portion 2d Annular groove 2e Through hole 3 Low melting point metal 4 Conical plug member 6 Fractal conical plug member 8 Cannonball shape Plug member

Claims (3)

A fusible stopper in which a straight through hole provided in the main body is filled with a low melting point metal that melts at a predetermined temperature,
A fusible plug, wherein a plug member having a pointed shape toward the open end side is loaded on the pressure receiving side of the through hole.   The fusible plug according to claim 1, wherein the peak shape of the plug member is any one of a conical shape, a truncated conical shape, and a bullet shape.   The fusible plug according to claim 1, wherein the plug member is formed of a material having a melting point higher than that of the low melting point metal.