JPH11273846A - Pipe heater having protective cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pipe heater from being damaged by avoiding the receiving directly of thermal shocks or drop impacts by covering the pipe heater with a metal protective cover. SOLUTION: This pipe heater is composed by covering a cylindrical pipe heater 11 with a protective cover 12 which has a thickness not more than 0.3 mm and is formed by shaping soft aluminum into a pipe having a regular octagon shape in its cross section perpendicular to the lengthwise direction in a manner for forming a space between the cylindrical pipe heater 11 and the cover. The damage of the quartz tube of an armoring sleeve that is low in mechanical strength is prevented by colliding the corner part of the protective cover 12 first with another thing and moderating the impact by deforming it, when the pipe heater is dropped by mistake. In addition, when water drops are attached to it at high temperatures, a thermal shock will not be imposed directly on the quartz tube, so that a crack can be prevented from occurring. Still additionally, because the protective cover 12 is made on aluminum and thereby has high thermal conductivity, the temperature distribution of its surface can be equalized, and the thermal conduction efficiency to a water supplying pipe can be improved. A polygonal pipe can be also used for the cross-sectional shape of the protective cover, without restricting it to a regular octagon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe heater used for preventing a water supply pipe of a water heater or the like from freezing, and more particularly to a pipe heater having a protective cover having an outer side covered with a protective cover.

[0002]

2. Description of the Related Art Conventionally, this kind of anti-freezing heater (hereinafter referred to as a pipe heater) is configured as shown in FIG. In FIG. 2, reference numeral 1 denotes an outer sleeve made of a heat-resistant inorganic material, for example, a quartz tube is used. Reference numeral 2 denotes an air-core coil-shaped resistance element inserted into the exterior sleeve 1, and heat-resistant lead wires 4 are joined to both ends thereof via relay terminals 3. Numeral 5 denotes a powdery insulating material filled in the exterior sleeve 1 so as to fill the resistance element 2, for example, zircon sand powder. 6 is a resistance element 2
Is a sealing material that seals both ends of the exterior sleeve 1 into which is inserted.

The conventional pipe heater configured as described above is disposed along a water supply pipe of, for example, a water heater, and prevents current from flowing through the resistance element 2 to generate heat to prevent freezing of the water supply pipe. Can be.

[0004]

However, in the above-described conventional pipe heater, when a quartz tube is used for the outer sleeve, if water droplets are applied to the quartz tube at a high temperature,
Since it is locally cooled, it may crack and break. In addition, since the quartz tube has poor mechanical strength, there is a problem that the quartz tube is dropped during manufacturing or during a mounting operation on a water supply pipe, and is damaged by an impact.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a pipe heater which is prevented from being damaged by directly receiving a thermal shock or a drop impact. Aim.

[0006]

In order to achieve this object, a pipe heater according to the present invention has a heater element placed in an outer sleeve made of a heat-resistant inorganic substance, filled with a powdery insulating material, and sealed at both ends. The pipe heater sealed with a material is covered with a protective cover made of metal.

Here, when the cross section of the pipe heater is circular, the cross section of the protective cover is polygonal, and when the cross section of the pipe heater is substantially polygonal, the cross section of the protective cover is circular. A space is created between the cover and the protective cover, which acts as a cushion against thermal shock and drop impact. Further, the protective cover may be formed in a cylindrical shape, but may be wound around a pipe heater with a metal sheet as a core.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a pipe heater with a protective cover according to an embodiment of the present invention, where 11 is a pipe heater and 12 is a protective cover.

The pipe heater 11 may have the same configuration as the conventional one as shown in FIG. 2, for example. That is, reference numeral 1 denotes an outer sleeve made of a heat-resistant inorganic material, for example, a quartz tube having a circular cross section perpendicular to the length direction. 2 is an air-core coil-shaped resistance element inserted in the outer sleeve 1;
Heat-resistant lead wires 4 are respectively connected to both ends via relay terminals 3. Reference numeral 5 denotes a powdery insulating material filled inside the outer sleeve 1 so as to fill the resistance element 2.
For example, zircon sand powder. Reference numeral 6 denotes a sealing material that seals both ends of the exterior sleeve 1 into which the resistance element 2 is inserted.

The protective cover 12 has a thickness of, for example, 0.1 mm.
Aluminum (soft) of 3 mm or less is used, and its shape is a regular octagon in a cross section perpendicular to the length direction as shown in FIG.

According to the above-described embodiment, since the cylindrical pipe heater 11 is covered with the regular octagonal metal protective cover 12, the corner of the protective cover 12 is covered with the pipe heater. 11 and a space is formed. Therefore, when the pipe heater with the protective cover is dropped, the probability that the corner of the protective cover 12 first collides with another object is increased, and the portion is deformed.
Reduce the impact. For example, the results of a test in which a pipe heater was dropped on a rod-shaped object so as to intersect at right angles and whether the quartz tube was damaged or not were compared with those without a conventional protective cover (Table 1). ). X represents breakage.

[0012]

[Table 1]

Thus, it can be seen that the pipe heater with the protective cover is less likely to be damaged than the pipe heater without the protective cover. Further, even when water droplets are applied to the pipe heater with the protective cover at high temperatures, no crack is generated because no direct thermal shock is applied to the quartz tube. In addition, the protective cover made of metal with good heat conductivity is covered, so the internal heat is drawn out, the temperature distribution on the surface is averaged, and the efficiency of conducting heat to the water supply pipe is improved. Can be

FIG. 4 shows an example in which various shapes of the pipe heater and the protective cover are combined, and FIG.
Has a circular cross section of the pipe heater 14 and a protective cover 15
4B is an octagonal section, FIG.
6 is circular and the cross section of the protective cover 17 is triangular, FIG. 4C shows a case where the cross section of the pipe heater 18 is substantially triangular and the cross section of the protective cover 19 is circular. In any of these cases, a space is formed between the pipe heater and the protective cover.

Further, the protective cover may be formed in advance into a cylinder or a polygonal cylinder, but as shown in FIG.
Simply, a pipe heater may be used as a core, and the outside may be formed by roll winding with a metal sheet. In this case, for the metal sheet, a material that undergoes plastic deformation while being wound into a roll is selected.

The outer sleeve of the pipe heater is not limited to a quartz tube, but may be a ceramic sleeve.

[0017]

As described above, according to the present invention,
By covering the metal heater with a metal protective cover over a pipe heater having an outer sleeve made of a heat-resistant inorganic material, the outer sleeve can be protected from thermal shock and mechanical shock. However, the problem that the life is shortened can be solved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a pipe heater with a protective cover according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a pipe heater.

FIG. 3 is a perspective view showing an example of a protective cover of the present invention.

FIG. 4 is a view showing various examples of combinations of a pipe heater and a protective cover according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer sleeve 2 Resistance element 3 Relay terminal 4 Lead wire 5 Powdery insulating material 6 Sealing material 11, 14, 16, 18 Pipe heater 12, 15, 17, 19 Protective cover

Claims (4)

[Claims] 1. A heater element is placed in an outer sleeve made of a heat-resistant inorganic material, a pipe heater filled with a powdery insulating material and both ends are sealed with a sealing material, and a protective cover made of metal is put on the pipe heater. A pipe heater with a protective cover, characterized in that: 2. The pipe heater has a circular cross section, and the protective cover has a polygonal cross section.
The pipe heater as described. 3. The pipe heater has a substantially polygonal cross section.
The pipe heater according to claim 1, wherein the protective cover has a circular cross section. 4. The pipe heater according to claim 1, wherein the protective cover is made of a pipe heater as a core and the outside thereof is rolled with a metal sheet.