JP2002359061A - Electric heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric heater having a heater element hard to fall off from the insulator. SOLUTION: This electric heater has the plate-like heater element 20 for forming a current passage by forming a slit, and the insulator 10 for respectively supporting width end parts 22 crossing the slit among this heating element 20. The heater element 20 is formed in a gentle circular arc shape between a pair of width end parts 22. The respective width end parts 22 are bent toward the outside of a circular arc, and are engaged with the insulator 10. This insulator 10 is dividedly formed as first and second divided bodies 11a and 12a. Since a required process is only to uniformly bend the width end parts 22 of the heater element 20, even if the slit is formed, the width end parts 22 do not partially fall off, and warping of the heater element 20 is hardly caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric heater. More specifically, the present invention relates to an electric heater including a plate-like heating element having a current path formed by forming a slit, and insulators respectively supporting both ends in the width direction of the heating element that cross the slit.

[0002]

2. Description of the Related Art Conventionally, as an electric resistance heating element 120 used for an electric heater, as shown in FIGS. Things are known. The heating element 12 is formed by a rod-shaped insulator 110 having a support portion 111.
The electric heater 100 was configured by supporting both end portions 122 in both width directions.

However, if this type of electric heater 100 is continuously used, the widthwise end 122 of the heating element 120 may fall off the insulator 110 in some cases. Further, reference numerals e1 to e1
Only some of the ends shown at e4 may fall off the insulator 110, causing a so-called "rack" of the heating element 120, such as riding on another heating element portion.

[0004] In particular, in addition to the support portion 111 described above,
There may be a second support portion 112 such as a heat insulating material that sandwiches the width direction end 122 together with the support portion 111. In this case, the first and second support parts 111 and 112 and the width direction end 1
22 is likely to be non-uniform between the plurality of end portions indicated by reference numerals e1 to e4, and thus the above-mentioned “roughness” may be further expanded due to the effect of the non-uniform friction coefficient. .

[0005]

SUMMARY OF THE INVENTION In view of such a conventional situation, an object of the present invention is to provide an electric heater in which a heating element is hardly dropped from an insulator.

[0006]

As shown in FIG. 11, when a heating element 120 of this kind shifts from a normal state indicated by reference numeral 120a to a thermal expansion state by energization indicated by reference numeral 120b, the heating element 120 Both width direction ends 121x, 121y
To the pair of insulators 110, 110, respectively. With this tension, the heating element 120 is further bent so as to reduce the radius of curvature of the curve.
Thereafter, when the state is shifted to the cooling state indicated by the reference numeral 120c, the bending state of the entire heating element 120 does not change and both end portions 1 in the width direction are not changed.
Only the span between 21x and 121y may decrease. According to the experiments and considerations of the inventors, such a situation causes the widthwise end 121x of the heating element 120 to move away from the insulator 110.
It has been found that the heating element may fall off or the heating element may be ramped up.

Therefore, in order to achieve the above object, the electric heater according to the present invention is characterized in that a plate-like heating element having a current path formed by forming a slit, and a width of the heating element crossing the slit. In the configuration provided with an insulator supporting each end in the width direction, the end in the width direction is bent and engaged with the insulator.

According to this feature, it is sufficient for the heating element to be simply processed by bending the end in the width direction. For example, the processing is extremely simple as compared with the case where a fixing hole is formed in the heating element, and has almost no effect on the current path design. Further, since only the bent width direction end of the heating element is engaged, the configuration of the insulator is extremely simple and easy to manufacture. Then, since the width-direction ends may be uniformly bent, even if the above-described slits are formed, the width-direction ends of the heating elements do not fall off partially, and the above-mentioned "heat ramp" Is also unlikely to occur.

Preferably, the heating element is formed in a gentle arc or straight line between the pair of widthwise ends. This is because if a local bend is present between both widthwise ends, the bend due to the thermal expansion described above tends to concentrate on the local bend. When the heating element is formed in a gentle arc between the pair of ends in the width direction, the both ends in the width direction may be bent toward the outside of the arc.

In the case where the widthwise ends are bent to form a bent portion, the insulator is divided into first and second divided bodies, and the bent parts are engaged with these divided bodies. It is preferable to provide a locking portion and a pressing portion for pressing the width direction end, and to provide a clearance between the locking portion and the pressing portion to allow movement of the bent portion. This is because the clearance allows the bent portion to move and absorbs deformation due to thermal expansion of the heating element. Still other objects, configurations, and effects of the present invention will become apparent in the following “Embodiments of the invention” section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, referring to the attached drawings,
The present invention will be described in more detail. As shown in FIGS. 1 to 3, the electric heater 1 according to the first embodiment of the present invention includes:
It is installed mainly on the furnace ceiling, etc.
The frame 2 includes a frame 2 made of a steel material, an insulator 10 fixed to the frame 2, and a heating element 20 supported by the insulator 10. The frame 2 is composed of a channel-shaped vertical frame 3 and a horizontal frame 4 connecting the vertical frames 3 to each other.
And a fixing pin 5 protruding from the vertical frame. The upper opening of the vertical frame 3 is intermittently fixed by the auxiliary member 3a to prevent deformation.

The insulator 10 comprises a first divided body 11a and a second divided body 12a arranged along the vertical frame 3.
The first and second divided bodies 11a and 12a are made of a so-called ceramic material or silicon nitride material mainly composed of alumina, alumina-silica, mullite, zircon or cordierite.
Are electrically insulated from each other. Each of the first and second divided bodies 11a, 1
2a has a fixing pin 5 projecting downward from the vertical frame 3.
Is formed. And
By penetrating the fixing pin 5 and penetrating and enlarging the split pin 6 into a small through hole laterally penetrating the tip of the fixing pin 5,
Each of the first and second divided bodies 11a and 12a is fixed to the vertical frame 3.

The heating element 20 has a meandering current path by alternately cutting a plurality of slits 21 on opposite sides of a plate-shaped and rectangular or strip-shaped electric resistance heating element. I have. In this specification, a pair of ends 22, 22 of the heating element 20 intersecting the slit 21 at right angles, that is, ends along the vertical frame 3 in the width direction of the heating element 20 are referred to as “width direction ends” in this specification. Name. Heating element 2
The space between the pair of widthwise ends 22 at 0 is formed so as to form a gentle arc (arch shape) when viewed in the longitudinal direction of the vertical frame 3. The heating element 20 is bent in a shape that is convex upward, and when the heating element 20 generates heat, compressive stress mainly acts uniformly on each part in combination with gravity to maintain an arched shape. .

In addition, in the present embodiment, the widthwise ends 22 of the heating element 20 are directed upward, that is, upward in the present embodiment.
Are bent orthogonally to form a bent portion 23. The bending of the bent portion 23 may be performed after the slit 21 is formed in the plate material.

As shown in FIGS. 3 and 4, the first divided body 11a
A narrow portion 15 is formed between the opposing surfaces along the substantially horizontal direction between the locking portion 13 of the second member 12 and the pressing portion 14 of the second divided body 12a, and a clearance is formed between the opposing surfaces along the substantially vertical direction. 16
Is formed. The bent portion 23 is locked by the locking portion 13 of the first divided body 11a. In addition, the lower surface 24 of the heating element 20 at the width direction end 22 is pressed by the pressing portion 14 of the second divided body 12a so as not to fall downward. That is, the locking portion 13, the narrow portion 15, and the bent portion 23 work together to prevent the end portion 22 in the width direction from coming off in the direction of arrow D1 when the heat generating member 20 is thermally contracted. On the other hand, the clearance 16 is part of the extension deformation of the heating element 20 when the heating element 20 thermally expands, specifically, the bent portion 23 is moved from the position 23a to the position 23b in FIG. The extension deformation in the direction of the arrow D2 can be absorbed.

Next, another embodiment of the present invention will be described. Note that the same reference numerals are given to the same members as those in the above-described embodiment, and a description will be given mainly of a portion different from the above-described embodiment.

The second embodiment shown in FIG. 5 relates to an electric heater 1 used mainly for floors. In this embodiment, the frame 2 and the insulator 10 have an upside-down relationship with the first embodiment. Further, the heating element 20 is bent in an arch shape so as to form a gentle arc shape having a convex upper side. In the present embodiment, the holding portion 14 is formed on the first divided body 11b attached to the vertical frame 3, and the locking portion 13 is formed on the second divided body 12b.

Although the heating element may be formed in a straight line as indicated by reference numeral 20a in FIG. 5, when the electric heater 1 is arranged horizontally, it is preferable to form the heating element in an arc shape as described above. Desirable from the nature. Therefore, when the electric heater 1 is arranged so that the width direction of the heating element 20, that is, the longitudinal direction of the horizontal frame 2 is vertically oriented, the heating element is formed in a straight line as indicated by reference numeral 20 a. It is desirable.

In the third embodiment shown in FIG. 6, unlike the first embodiment, the heating element 20 is formed so as to project downward. In this case, the holding portion 14 is formed on the first divided body 11c fixed to the vertical frame 3, and the second divided body 12c
Is formed with a locking portion 13.

In the fourth embodiment shown in FIG. 7, unlike the first embodiment, the inside of the arc formed by the heating element 20, that is,
In the present embodiment, the bent portion 23 is formed by bending each width direction end 22 orthogonally downward. Even with the same configuration, the removal of the width direction end portion 22 is prevented,
The width of the concealed portion indicated by the symbol W by the second divided body 12d is increased, and the heat radiation efficiency of the heating element 20 is reduced. Therefore, from the viewpoint of heat radiation efficiency, it is desirable to bend the width direction end 22 to the outside of the arc formed by the heating element 20.

In the fifth embodiment shown in FIG. 8, unlike the first embodiment, the insulator 10 has a first divided body 11 having an inverted T-shaped cross section.
e and two plate-shaped second divided bodies 12e. The end 22 in the width direction of the heating element 20 is formed as a hook-shaped bent portion 23, and the pressing portion 14, which is the lower end of the second divided body 12 e, is formed along the upper surface of the bent portion 23. On the other hand, the lower left and right portions of the first divided body 11e are formed as locking portions 13 that lock inside the bending portion 23 and prevent the bending portion 23 from coming off in combination with the pressing portion 14. The upper end of the second divided body 12 e is fixed by a channel material 17 penetrated by the pin 5.

In the fifth embodiment, an inverted bent portion 25 having a radius of curvature extremely smaller than the gentle bending of the middle portion of the heating element 20 is formed near the width direction end portion 22. However, if the deformation is concentrated on the inverted bent portion 25 due to the thermal expansion of the heating element 20, the inverted bent portion 25 is not provided between the pair of width direction ends 22, 22, and the pair of width direction ends is not provided. It is desirable to form the heating element 20 in a gentle arc or straight line between the portions 22.

Reference will be made to yet another embodiment of the present invention. In the above embodiment, a meandering current path is formed by alternately forming the slits 21. However, the form of the slits 21 is not limited to the above-described embodiment, for example, the slits 21 are formed alternately at every third interval, or the slits 21 are fixed to the middle in the width direction of the plate.

In each of the above embodiments, the frame 2 is made of a steel material. However, the frame 2 may be made of a non-combustible material such as ceramic wool.

[0025]

As described above, according to the present invention, it is possible to provide an electric heater with a simple structure, in which the heating element hardly falls off the insulator and the heating element hardly runs out. As a result, the durability of the electric heater can be improved, the life of manufacturing equipment and the like using the heater can be extended, and the production efficiency can be improved.

It should be noted that the reference numerals described in the claims are merely for convenience of comparison with the drawings, and the present invention is not limited to the configuration of the attached drawings by the description. .

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an electric heater according to a first embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a longitudinal sectional view near an insulator.

FIG. 4 is a longitudinal sectional view showing a relationship between an insulator and a widthwise end of a heating element.

FIG. 5 is a longitudinal sectional view of an electric heater according to a second embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing the vicinity of an insulator according to a third embodiment of the present invention.

FIG. 7 is a longitudinal sectional view showing the vicinity of an insulator according to a fourth embodiment of the present invention.

FIG. 8 is a longitudinal sectional view showing the vicinity of an insulator according to a fifth embodiment of the present invention.

FIG. 9 is a longitudinal sectional view of the vicinity of an insulator in a conventional example.

FIG. 10 is a bottom view of an electric heater in a conventional example.

FIG. 11 is a schematic diagram showing a relationship between thermal expansion / contraction of a heating element and an insulator.

[Explanation of symbols]

1: electric heater, 2: frame, 3: vertical frame, 3
a: auxiliary material, 4: horizontal frame, 5: fixing pin, 6: split pin, 10: insulator, 11a to 11e: first divided body, 12a
１２12e: second divided body, 13: locking portion, 14: pressing portion, 15: narrow portion, 16: clearance, 17: channel material, 20: heating element, 21: slit, 22: end in width direction, 23: bent portion, 24: lower surface, 25: inverted bent portion,
100: electric heater, 110: insulator, 111: support, 112: second support, 120: heating element, 121: slit, 122: end in width direction

Continuation of the front page (72) Inventor Kenji Maeda 426-1 Ozawa Uehara, Kakuda, Aikawa-cho, Aiko-gun, Kanagawa Prefecture F-term in Asahi Glass Co., Ltd. 3K092 PP09 QB32 RF28 TT17 VV26 VV36

Claims (4)

[Claims] 1. A plate-shaped heating element (20) having a current path formed by forming a slit (21), and a width direction end (22) of the heating element (20) intersecting the slit (21). , 22) respectively supporting the insulator (10), wherein the width direction ends (22, 2) are provided.
2) An electric heater in which each is bent and engaged with the insulator (10). 2. The electric heater according to claim 1, wherein the heating element (20) is formed in a gentle arc or linear shape between the pair of width direction ends (22, 22). 3. The heating element (20) is formed in a gentle arc shape between a pair of the width direction ends (22, 22), and each of the width direction ends (22, 22) is formed of the arc shape. 2. The electric heater according to claim 1, wherein the electric heater is bent outward. 4. A bent portion (23) is formed by bending each end (22, 22) in the width direction, and the insulator is divided into first and second divided bodies (11a to 11d, 12a to 12d). Formed, and these divided bodies (11a to 11d, 12a to 12d)
A locking portion (13) for locking the bent portion (23) and a pressing portion (14) for pressing the width direction end portion (22), and the locking portion (13) and the pressing portion (14) are provided. The electric heater according to any one of claims 1 to 3, further comprising a clearance (16) for allowing the movement of the bent portion (23).