JPS593233A - Construction and method for sealing up power element temperature sensing section - Google Patents

Abstract

PURPOSE:To elevate the reliability and durability by preventing the electrochemical corrosion and gas leak of a temperature sensing section by crushing the tip of the thermo-sensitive part of a power element to form a semi-circular arc in the cross-section with the diameter thereof almost equal to the thermosensitive part and sealing up the crushed part by fusion. CONSTITUTION:The tip 2 of the thermosensitive part 1 of a power element formed by swaging and reducing the other end of a stainless steel pipe is crushed with a die 4 which has a concave 4a with a semi-circular arc cross-section almost equal in the diameter D3 to the diameter D1 of the thermosensitive part 1 and a die 5 which has a convex 5a with a semi-circular cross-section equal in the diameter D4 to D1-2t1 with the thickness t1 of the part 1. The crushed part undergoes an argon welding, a laser beam welding or the like to form a seal-up section 7 with the diameter D2 almost equal to the diameter D1. Thus, an element is obtained simply and at a low cost with a seal-up construction easy to mount a shell such as a boiler and excellent in the reliability and durability free from electric corrosion, leak of gas or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing structure and a method for sealing a thermosensing part of a thermal element.

For example, in hot water boilers, water heaters, etc., when controlling the start and stop of burners depending on the water temperature, power
The temperature sensing part is immersed directly into the can to measure the temperature of the water.

In this kind of power element temperature-sensing part, a thin tube leading to a heros etc. is connected to the rear end, and the tip +Mi
For example, l is sealed in the following manner.

■ After swaging the tip, crush it into a flat shape and wax it.

■ After swaging the tip, crush it into a flat shape and spot weld it.

■ Melting after swaging the tip.

■ Cover the tip with 21-Yasobu and braze it.

However, according to Power Niremen 1 to Temperature Sensing Part, the tip is swaged to seal it (in the case of ■, ■, ■), which is costly, and it is brazed. (In the case of ■, ■), a local battery is formed by dissimilar metals between the base metal and the filler metal, which undergoes electrochemical corrosion and generates vinyl poles, etc., and the temperature-sensitive part waxes even though there is no abnormality in other parts. There are problems such as accidents where the control device becomes unusable due to corrosion of the parts.

In addition, even in the case of spot welding, there is a risk of gas leakage and reliability is lacking.

The present invention has been made in view of the above circumstances, and its purpose is to provide a temperature-sensitive power element that does not require swaging or brazing, is inexpensive, has no fear of corrosion, and is reliable. An object of the present invention is to provide a sealing structure and a method for sealing the same.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1a is a partial sectional view showing an example of the sealing structure of the present invention. In the figure, reference numeral 1 denotes a temperature-sensitive cylinder, which is made of stainless steel pipe, and its rear end is swaged twice to reduce its diameter (as shown in Figure 2). Although not shown, there is a thin tube leading to a heros, etc. It is now connected.

On the other hand, the tip of the temperature-sensitive tube 1 is crushed into a semicircular cross-section having a diameter 1)2 approximately equal to the diameter D+ of the temperature-sensing tube 1 (see FIG. 1). This crushed portion 2 is fused and sealed by argon welding or the like.

Therefore, even if the temperature-sensitive tube 1 is immersed in a liquid, the sealing portion 7 does not constitute a local battery made of dissimilar metals, and is therefore not subject to electrochemical corrosion. In addition, there is no risk of gas leakage, unlike when welding.

FIGS. 2a to 2d show an example of a method for manufacturing a temperature-sensitive cylinder to which the sealing method of the present invention is applied.

First, as shown in FIG. 2a, the stainless steel pipe S constituting the temperature sensing ff11 is heat treated. Next, as shown in the same figure, one end of the stainless steel pipe S (the part that will become the rear wheel of the temperature sensing cylinder 1) is swaged to reduce its diameter. Then, heat treatment is performed to remove the work hardening caused by this swaging process, and as shown in FIG.

Next, the opening at the other end of the stainless steel pipe S is sealed by the sealing method 1F of the present invention, using a press device 3 as shown in FIG. 3. This press device 3 is
Diameter D+ of thermosensitive cylinder L (diameter of stainless steel pipe S)
The four parts 4a have a semicircular cross section and have a diameter D3 approximately equal to
The diameter D+ is obtained by subtracting the wall thickness (thickness of the stainless steel pipe S) from the diameter D) of the mold 4 and the temperature-sensitive cylinder 1.
The mold 5 is formed with a convex portion 5a having a semicircular cross section and having a diameter approximately equal to 2t1.

To seal, first insert the other end of the stainless steel pipe S (the part that becomes the tip of the temperature-sensitive cylinder 1) into the recess 4a of the mold 4, and then insert the other end of the stainless steel pipe S into the convex part 5a of the mold 5. Press the outer peripheral surface of the container to crush it. As a result, the other end of the stainless steel pipe S is formed into a semicircular cross-section having a diameter that is approximately equal to the diameter of the stainless steel pipe S. Thereafter, the IF collapsed portion 2 is fused by welding means such as argon welding or laser beam welding. After that, heat treatment is performed to remove work hardening.

The heat treatment in each step of the two sides is performed by heating in a vacuum furnace at a temperature of 1030°C for 60 minutes, and then rapidly cooling in a nitrogen gas atmosphere.

In Example 1-, only one end of the stainless steel pipe S is swaged, and the other end of the stainless steel pipe S, which corresponds to the tip of the temperature sensing cylinder 1, is not swaged. The temperature-sensitive cylinder 1 is not manufactured by swaging both ends (the processing cost can be lowered compared to the conventional method).

The sealing structure of the present invention can be used not only in liquids but also in corrosive gases such as ammonia gas without any problems.

As explained above, according to the present invention, in order to seal the tip of the temperature-sensing portion (temperature-sensing cylinder) in advance by performing swaging processing, the tip portion is simply swaged to approximately the diameter of the temperature-sensing portion. The cost is low because it is simply pressed into a semicircular cross-sectional shape with the same diameter and the crushed portion is sealed by fusion, and since brazing has no parts, it is not subject to electrochemical corrosion.

Also, unlike spot welding, there is no risk of leakage.

Therefore, reliability can be improved.

In addition, the dimensions of the seal 1F part are not larger than the diameter of the temperature-sensitive part, so there is no problem when installing it by inserting it through the mounting hole of the can body, and the mounting hole can be made as large as necessary. Since it is not necessary, it is possible to easily seal between the temperature sensing part and the mounting hole.

In other words, compared to the case of swaging, the length and width of the temperature-sensitive portion can be shortened even though the internal volume remains the same.

Furthermore, sealing does not require any special equipment; only a simple press device is required, and equipment costs are low.

[Brief explanation of drawings]

Fig. 1a is a partial sectional view showing an embodiment of the sealing structure of the present invention, and a front view of the same figure, Figs. Explanatory diagram explaining the third
The figure is a schematic diagram of a press device used in the sealing method of the present invention. ■...Temperature sensing part (temperature sensing tube), 2...Crushing part, 3.
...Press device, 4a...Concave portion, 5a...Convex portion, 4
, 5...Mold, 7... Sealing part. Patent applicant: Saginomiya Seisakusho Co., Ltd. Figure 1 (G) 3 Niwo. 6゜-

Claims (2)

[Claims] (1) A power element characterized in that the tip of the temperature sensing portion is crushed into a semicircular cross-sectional shape having a diameter approximately equal to the diameter of the temperature sensing portion, and the crushed portion is sealed by fusion bonding. Sealing structure of temperature sensing part. (2) A mold in which a recess with a semicircular cross section having a diameter approximately equal to the diameter of the temperature sensing portion is formed, and a semicircular cross section having a diameter approximately equal to the diameter of the temperature sensing portion minus its wall thickness. a step of crushing the tip of the temperature-sensitive portion into a lli-plane arc shape having a diameter approximately equal to the diameter of the temperature-sensing portion using a press device equipped with a mold having a shaped convex portion;
11. A method for sealing a temperature sensing portion of a power element, comprising the step of fusing and sealing this crushed portion using a welding means such as argon welding or laser beam welding.