JP2003086336A - Cartridge heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cartridge heater with simple structure and high heat conductivity in axial direction. SOLUTION: The cartridge heater 1 comprises a corrosion resistant outer sheath tube 2, an electric heating element 3a arranged inside the outer sheath tube 2, and an inorganic insulator 4 separating the electric heating element 3a from the outer sheath tube 2, and at least the top end part of the outer sheath tube 2, including the electric heating element 3a and the inorganic insulator 4, is integrated by contracting their diameter. A metal inner tube with good heat conductivity is arranged at the inner surface 20 of the outer sheath tube 2, and at least the top end part of the inner tube 5 is contracted and integrated with the outer sheath tube 2, the electric heating element 3a, and the inorganic insulator 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cartridge heater.

[0002]

2. Description of the Related Art Conventionally, a cartridge heater has been widely used as a heating source for household or industrial electric machines and appliances. As a conventional cartridge heater, Japanese Unexamined Patent Publication No. 7-50195 discloses a sealed pipe, a heater provided in the sealed pipe, a thermal fuse axially separated from the heater, and a thermal fuse provided from the heater. A cartridge heater including a heat transfer rod that transfers heat is disclosed.

When the cartridge heater is used abnormally,
For example, the temperature fuse is blown when used without a liquid to be heated to prevent abnormal heating of the cartridge heater. The heat transfer rod quickly transmits the temperature of the heater by a temperature fuse, detects an abnormal temperature rise of the heater, cuts off the power supply to the heater, and prevents the cartridge heater from being abnormally heated.

[0004]

In this conventional cartridge heater, a metal rod which is a heat transfer rod is provided at the center of the sealed pipe. Since there is a conducting wire or the like for energizing the heater in the central portion of the hermetically sealed pipe, it is necessary to maintain insulation with the heater and the conducting wire, and there is a problem that attention must be paid to the arrangement of the heat transfer rods.

The present invention has been made in view of the above-mentioned problems, and can improve the heating performance for an object to be heated and can reduce the cost with a simple structure. It is an object of the present invention to provide a cartridge heater which has an excellent function of transferring heat from the outer tube to the disposed temperature fuse, enhances the function of the temperature fuse, and prevents peripheral devices from being affected by heat.

[0006]

A cartridge heater according to the present invention comprises an outer tube made of corrosion-resistant metal, an electric heating element disposed in the outer tube, and an inorganic electrical insulator for separating the outer tube from the electric heating element. A cartridge heater in which at least a tip portion of the outer tube including the energization heating element and the inorganic electrical insulator is reduced in diameter and integrated, and good heat conduction to the inner peripheral surface side of the outer tube. It is characterized in that it has an inner tube made of a functional metal, and at least the tip portion of the inner tube is subjected to the diameter reduction integral treatment together with the outer tube, the electric heating element and the inorganic electrical insulator.

Since the cartridge heater of the present invention has the inner tube made of a good heat conductive metal, when the cartridge heater is used, even if the energized heating element has uneven heat generation, the cartridge heater is made to pass through the inner tube made of a good heat conductive metal. The heat is transferred in the same direction to the entire area,
Can transfer heat uniformly and quickly.

Therefore, the heating function for the object to be heated outside the exterior tube can be enhanced with a simple structure having the inner tube made of a metal having good thermal conductivity.

Further, when the present invention is applied to a cartridge heater equipped with a temperature fuse, the ambient temperature of the cartridge heater is set to a regular heating temperature (set temperature) during abnormal use (for example, when the heater is dry without heating liquid). When the upper limit is exceeded, heat can be quickly transferred to the thermal fuse in the axial direction through the inner tube made of a metal having good heat conductivity inside the outer tube.

Therefore, at the time of abnormal use in which the thermal fuse needs to function, the heat transfer from the outer tube to the thermal fuse is fast, and it is possible to quickly interrupt the energization of the energizing heating element.

Further, since the inner tube is integrated with the outer tube, there is no problem caused by disposing the metal piece (good heat transfer member) in the central portion of the cartridge heater as in the conventional case.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The cartridge heater of the present invention comprises an outer tube, an electric heating element, an inorganic electrical insulator, and an inner tube.

The outer tube is made of a corrosion resistant metal. The outer tube has rigidity and durability and withstands use at high temperature, and protects the energizing heating element, the inorganic electric insulator, the inner tube, the thermal fuse, and the like arranged inside in a sealed state. Alloy steel or titanium-based metal can be used as the corrosion-resistant metal.

The energization heating element may be any one as long as it generates heat when energized, and a sheet-shaped or cylindrical heating element or a coil-shaped nichrome wire can be used.

The inorganic electric insulator protects the electric heating element and keeps the electric heating element insulated from the inner tube and the outer tube. As the inorganic electrical insulator, for example, magnesia,
Ceramics such as alumina can be used.

The inner tube is made of a metal having good thermal conductivity, and uniformly and quickly transfers the heat generated by the electric heating element to the entire area of the outer tube in the axial direction. Further, when the cartridge heater is abnormally used, the abnormal temperature rise of the electric heating element is quickly transmitted to the thermal fuse.

Examples of the good heat conductive metal include copper,
Aluminum or alloys thereof can be used.

At least the tip portion of the outer tube for accommodating the inner tube, the energization heating element and the inorganic electrical insulator is subjected to a diameter-reducing integration treatment so that the outer tube and the inner tube, the energization heating element, and the inorganic electrical insulator are not separated Integral for excellent heat transfer.

The cartridge heater of the present invention may have a thermal fuse arranged in the outer tube and the inner tube at an axial distance from the energization heating element.

The temperature fuse is an inner tube made of a good heat conductive metal inside the outer tube immediately when the ambient temperature of the cartridge heater exceeds the regular heating temperature (set temperature) upper limit during abnormal use of the cartridge heater. Through this, heat is quickly transmitted in the axial direction, the thermal fuse is melted, and the energization of the energization heating element is cut off.

As the thermal fuse, an intended one is selected from various operating temperature ranges set in advance and used.

The cartridge heater of the present invention is, for example,
Hot plate for welding and sealing, die and engraving, hot press
It can be used to heat a roller, various rollers, various molding dies, liquids and gases, and the like.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment applied to a cartridge heater having a temperature fuse as a cartridge heater of the present invention will be described with reference to FIGS.

The cartridge heater 1 of the embodiment comprises an outer tube 2, an electric heating element 3a arranged in the outer tube 2, an inorganic electrical insulator 4, an inner tube 5, and a thermal fuse 6. .

The outer tube 2 is made of stainless steel which is a corrosion resistant metal, and a bottomed cylinder having a predetermined overall length, outer diameter and inner diameter is used. The outer tube 2 has an opening 20 on one end side of the cylinder 2a.
A bottom plate 2b having a substantially semicircular cross section is arranged on a, and the entire circumference is welded to be integrated with the cylinder 2a. As the bottomed cylinder, one formed by deep drawing can be used.

The energization heating element 3a is an outer peripheral surface 30b of a cylindrical ceramic core (core material) 3b as an inorganic electric insulator.
A coiled nichrome wire that is spirally wound around is used.

2 of nichrome wire forming the electric heating element 3a
Terminals 3c and 3d for energization are connected to the one ends 31a and 32a, respectively.

The ceramic core 3b is shown in FIGS.
As shown in FIG. 3, two parallel holes 31b and 32b are provided along the axial direction.

The electric heating element 3a is spirally wound around the outer peripheral surface 30b of the ceramic core 3b, and the end portions 3 are formed in the holes 31b and 32b of the ceramic core 3b.
It is assembled with 1a and 32a inserted. Then, in the holes 31b and 32b of the ceramic core 3b,
The terminals 3c and 3d are inserted. Then, the terminals 3c and 3d have the holes 31b of the ceramic core 3b,
Inside 32b, the ends 31a and 32a of the electric heating element 3a are respectively connected.

A thermal fuse 6 is connected by two connecting pipes 33c at a position axially separated from the electric heating element 3a in the axial direction of the terminal 3c.
The terminal 3c and the thermal fuse 6 and the terminal 3d have cylindrical insulating tubes 7a, 7 at the position of the inner tube 5.
a is overlaid.

The electric heating element 3a, the ceramic core 3b, and the terminal 3 which are integrally assembled in this manner
The c and 3d and the thermal fuse 6 are arranged in a double tube in which the inner tube 5 is inserted into the outer tube 2.

The inner tube 5 is a cylinder made of copper, which is a metal having good thermal conductivity.

Next, the space S1 between the inner peripheral surface 50 of the inner tube 5 and the outer peripheral surface 30b of the electric heating element 3a and the ceramic core 3b is filled with powdery magnesia as the inorganic electrical insulator 4.

After that, the range in which the electric heating element 3a is wound and arranged and the range corresponding to the entire axial length of the ceramic core 3b are reduced in diameter together with the outer tube 2 and the inner tube 5,
It becomes consolidated and integrated so that heat can be easily transferred. A state in which the inorganic electrical insulator 4 and the inner peripheral surface 50 of the inner tube 5 are in close contact with each other, and the outer peripheral surface 51 of the inner tube 5 and the inner peripheral surface 20 of the outer tube 2 are in close contact with each other to facilitate heat transfer. Becomes

The terminals 3c and 3d, which are arranged in the double tube of the outer tube 2 and the inner tube 5, have openings 2 on the other end side of the cylinder 2a.
One end portions 32c and 32d protruding from 1a are connected to a power source through lead wires (not shown). Also,
The other end side opening 21a is filled with an insulating material (not shown).

The cartridge heater 1 of the embodiment constructed as described above is used by being arranged at a position where a heating object (not shown) can be heated.

That is, when the cartridge heater 1 is used, the energization heating element 3a generates heat due to the energization from the terminals 3c and 3d. Then, this heat is transferred from the inorganic electrical insulator 4 to the inner peripheral surface 50 of the inner tube 5 and the entire axial area of the inner tube 5, and the outer peripheral surface 51 of the inner tube 5 to the inner peripheral surface of the outer tube 2. Heat is transferred to 20 quickly and efficiently.

Here, for example, even if the energization heating element 3a has uneven heat generation, the inner peripheral surface 20 of the outer tube 2 and the entire axial area of the outer tube 2 are passed through the inner tube 5 made of copper, which is a good heat conductive metal. In addition, heat can be uniformly and quickly transferred without unevenness, and the object to be heated, which is in contact with the outer peripheral surface 21 of the outer tube 2, can be efficiently transferred and heated.

Therefore, the cartridge heater 1 of the embodiment is
Is a heating time capable of enhancing the heating function for the heating target outside the exterior tube 2 by a simple configuration having the inner tube 5 made of copper, which is a good heat conductive metal, and raising the temperature to a target temperature. Can be shortened.

Further, according to the cartridge heater 1 of the embodiment, when the energization heating element 3a of the cartridge heater 1 abnormally rises in temperature during abnormal use (for example, the heater is air-baked without a liquid to be heated), the inner tube Electric heating element 3 by 5
The temperature of a is transmitted to the thermal fuse 6 in the axial direction, the temperature of the thermal fuse 6 rises quickly, and the thermal fuse 6 melts.

Therefore, unlike the case of the conventional cartridge heater, the heat transfer in the axial direction is not performed quickly and the timing at which the temperature fuse functions is delayed, so that the ambient temperature of the cartridge heater rises to an abnormally high temperature. It is possible to prevent the peripheral devices from being thermally affected by an abnormally high temperature without continuing.

Therefore, the cartridge heater 1 of the embodiment
Has a simple structure and is excellent in uniform heat transfer function. Further, the heat transfer in the axial direction is excellent at the time of abnormal use, and the thermal fuse 6 can be quickly fused by heating. For this reason, it is possible to minimize the influence of heat of the devices around the cartridge heater 1 during abnormal use.

(Test Example) Here, in order to confirm that the function of the thermal fuse 6 can be enhanced when the cartridge heater 1 of the above-described embodiment is abnormally used (for example, when the heater is dry without a liquid to be heated). The air-cooling current test was conducted under the following conditions, and the results are shown in Table 1. -Test method (outline) The cartridge heater 1 of the example is baked at room temperature (room temperature) in a test container, and the thermal fuse 6 operates (function).
Check the time to do. -Sample (7 pieces) Energization to energization heating element 3a: 240V 1000W Room temperature: 28 to 30 ° C Thermal fuse 6: 95 ° C operation product

[0044]

[Table 1]

As the cartridge heater of the comparative example, the cartridge heater having the same structure as that of the cartridge heater 1 of the embodiment except that the inner tube 5 made of copper which is a good heat conductive metal is not used. It was created.
The air-heating test was conducted on the cartridge heater of this comparative example under the same conditions. In the case of the cartridge heater of this comparative example, the thermal fuse did not operate (function) even after an average of 1 minute or more, and was broken due to abnormal temperature rise.

As a result, in the cartridge heater 1 of the first embodiment, the temperature fuse is quickly blown during abnormal use, and abnormal heating of the cartridge heater due to abnormal use can be minimized.

[0047]

Since the cartridge heater of the present invention has the inner tube made of a metal having good thermal conductivity, heat can be easily transferred in the axial direction, and the heat can be uniformly and quickly transferred to the entire region.

Furthermore, when the present invention is applied to a cartridge heater equipped with a temperature fuse, abnormal temperature rise of the energizing heating element can be quickly changed to the temperature fuse during abnormal use (for example, in a state where the heater is dry without a liquid to be heated). It is possible to transmit, and it is possible to cut off the energization to the energization heating element by fusing the thermal fuse.

Further, since the inner tube is integrated with the outer tube, there is no problem caused by disposing the metal piece (good heat transfer member) at the center of the cartridge heater as in the conventional case.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cross section of a main part of a cartridge heater according to an embodiment.

FIG. 2 is an enlarged view of a cross section taken along the line AA in FIG.

FIG. 3 is an enlarged view of a cross section taken along the line BB in FIG.

FIG. 4 is a schematic perspective view showing a state in which an inner tube made of copper, which is a highly heat-conductive metal, is used in the cartridge heater of the embodiment.

[Explanation of symbols]

1 ... Cartridge heater 2 ... Exterior tube 3a
… Electrical heating element 3b… Ceramic core 4… Inorganic electrical insulator 5… Inner tube of good thermal conductive metal 6… Thermal fuse

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Claims (3)

[Claims] 1. An energization heating element and an energization heating element which have a sheath tube made of a corrosion-resistant metal, an energization heating element disposed in the encasement tube, and an inorganic electrical insulator separating the encasement tube and the energization heating element. A cartridge heater in which at least a tip portion of the outer tube containing an inorganic electrical insulator is subjected to a diameter-reducing integration treatment, and an inner tube of a good heat conductive metal is provided on an inner peripheral surface side of the outer tube. A cartridge heater characterized in that a tip end portion of an inner tube is integrated with the outer tube, the electric heating element, and the inorganic electrical insulator to reduce the diameter thereof. 2. The cartridge heater according to claim 1, further comprising a thermal fuse disposed in the outer tube and the inner tube with an axial distance from the energization heating element. 3. The cartridge heater according to claim 1, wherein the corrosion resistant metal is an alloy steel or a titanium-based metal, and the good heat conductive metal is copper, aluminum, or an alloy thereof.