JP4709427B2 - Electric heater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric heater. More specifically, the present invention relates to an electric heater including a plate-like heating element in which a current path is formed by forming a slit, and insulators that respectively support both end portions in the width direction intersecting the slit of the heating element.
[0002]
[Prior art]
Conventionally, as an electric resistance heating element 120 used for an electric heater, as shown in FIGS. 9 and 10, a plate-like heating element in which slits 121 are alternately formed on the left and right sides from the end 122 in the width direction is known. Yes. And the electric heater 100 was comprised by supporting both the width direction edge part 122 of the heat generating body 120 with the rod-shaped insulator 110 which has the support part 111. FIG.
[0003]
However, if this type of electric heater 100 is continuously used, the end 122 in the width direction of the heating element 120 may fall off the insulator 110. In addition, only some of the end portions indicated by reference numerals e1 to e4 may fall off the insulator 110 and cause a so-called “rambling” of the heating element 120 such as climbing on other heating element portions.
[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 portion 122 together with the support portion 111. In this case, the friction coefficient between the first and second support portions 111 and 112 and the width direction end portion 122 is likely to be nonuniform among the plurality of end portions indicated by reference numerals e1 to e4. As a result, the above-mentioned “rage” may be further expanded.
[0005]
[Problems to be solved by 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 unlikely to fall off from an insulator.
[0006]
[Means for Solving the Problems]
As shown in FIG. 11, when this type of heating element 120 shifts from the normal state shown by reference numeral 120a to the thermal expansion state by energization shown by reference numeral 120b, the heating element 120 has both width direction end portions 121x and 121y. The pair of insulators 110 and 110 are stretched respectively. By this stretching, the heating element 120 is further bent to reduce the curvature radius of the curve. Thereafter, when the cooling state indicated by reference numeral 120c is entered, only the span between both width direction end portions 121x and 121y may decrease without changing the bending state of the entire heating element 120. According to the experiments and considerations of the inventors, it has been found that, in such a situation, the end portion 121x in the width direction of the heating element 120 is dropped from the insulator 110, or the heating element is ramped.
[0007]
Therefore, in order to achieve the above object, the electric heater according to the present invention is characterized by a plate-shaped heating element in which a current path is formed by forming a slit, and a width direction end portion intersecting the slit of the heating element. The lever includes a locking portion for locking a bent portion formed by bending the width direction end portion and a pressing portion for pressing the width direction end portion. In addition, the width direction end portion is engaged with the insulator by the locking portion and the pressing portion.
[0008]
According to this feature, the heating element need only be subjected to simple processing that only bends 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 the current path design is hardly affected. Further, since only the bent width direction end of the heating element is engaged, the structure of the insulator is very simple and easy to manufacture. Since the width direction end portion only needs to be bent uniformly, even if the above-described slit is formed, the width direction end portion of the heating element is not partially dropped, and the above-described heating element “rambling” "Is also unlikely to occur.
[0009]
Desirably, the heating element may be formed in a gentle arc or straight line between a pair of widthwise ends. This is because if the local bent portion exists between both width direction end portions, the above-described bending due to thermal expansion tends to concentrate on the local bent portion. Moreover, when forming the said heat generating body in a gentle circular arc shape between a pair of said width direction edge part, it is good to bend each width direction edge part toward the outer side of the said circular arc.
[0010]
The insulator is divided into first and second divided bodies, and the divided portions are provided with the locking portion and the pressing portion, and the bent portion is moved between the locking portion and the pressing portion. It is advisable to provide a clearance that allows This is because the movement of the bent portion is allowed by the clearance, and the deformation due to the thermal expansion of the heating element is absorbed. Still other objects, configurations, and effects of the present invention will become apparent from the following “Embodiments of the Invention” section.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to the accompanying drawings.
As shown in FIGS. 1-3, the electric heater 1 concerning 1st embodiment of this invention is mainly installed in the ceiling etc. of a furnace, Comprising: The frame 2 comprised with a steel material, and this frame 2 and a heating element 20 supported by the insulator 10. The frame 2 includes a channel-shaped vertical frame 3, a horizontal frame 4 that connects the vertical frames 3 to each other, and a fixing pin 5 that protrudes from the vertical frame. The upper opening of the vertical frame 3 is intermittently fixed by the auxiliary material 3a to prevent deformation.
[0012]
The insulator 10 includes a first divided body 11a and a second divided body 12a arranged along the vertical frame 3. These 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, and the heating element 20 and the frame 2 Are electrically insulated from each other. Each of the first and second divided bodies 11a and 12a is formed with a through hole for allowing the fixing pin 5 protruding downward from the vertical frame 3 to pass therethrough. Then, each of the first and second divided bodies 11a and 12a is formed in the vertical frame 3 by penetrating the fixing pin 5 and penetrating and enlarging the split pin 6 into a small through hole penetrating the fixing pin 5 sideways. Fixed to.
[0013]
The heating element 20 is configured to have a meandering current path by alternately cutting a plurality of slits 21 on opposite sides of an electric resistance heating element formed in a plate shape, a rectangular shape, or a strip shape. . In this specification, a pair of end portions 22 and 22 that intersect perpendicularly to the slit 21 in the heating element 20, that is, an end portion along the vertical frame 3 in the width direction of the heating element 20 is referred to as a “width direction end portion” in this specification. Called. A space between the pair of width direction end portions 22 of the heating element 20 is formed so as to form a gentle arc shape (arch shape) when viewed in the longitudinal direction of the vertical frame 3. The heating element 20 is bent into an upwardly convex shape, and is configured so that, when the heating element 20 generates heat, compressive stress is mainly applied uniformly to each part in combination with gravity to maintain an arched shape. .
[0014]
Further, the bent portions 23 are formed by bending the width direction end portions 22 in an orthogonal shape toward the outside of the arc formed by the heating element 20, that is, upward in the present embodiment. The bending process of the bent portion 23 may be performed after the slit 21 is formed on the plate material.
[0015]
As shown in FIGS. 3 and 4, a narrow portion 15 is provided between the opposing portions along the substantially horizontal direction between the locking portion 13 of the first divided body 11 a and the pressing portion 14 of the second divided body 12 a. A clearance 16 is formed between the opposing surfaces that are formed and are substantially perpendicular. The bent portion 23 is locked by the locking portion 13 of the first divided body 11a. Further, the lower surface 24 of the heating element 20 at the end 22 in the width direction is pressed by the pressing part 14 of the second divided body 12a so as not to come down downward. That is, the locking portion 13, the narrow width portion 15, and the bent portion 23 combine to prevent the width direction end portion 22 from coming off in the direction of the arrow D <b> 1 when the heating element 20 is thermally contracted. On the other hand, the clearance 16 is a part of the expansion and deformation of the heating element 20 during the thermal expansion of the heating element 20, specifically, the bent portion 23 moves from the position 23a in FIG. It is possible to absorb the extensional deformation in the direction of the arrow D2.
[0016]
Next, another embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the member similar to the said embodiment, and a different part from the said embodiment is mainly demonstrated.
[0017]
The second embodiment shown in FIG. 5 relates to an electric heater 1 mainly used for flooring. In the present embodiment, the frame 2 and the insulator 10 are upside down with respect to 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 this embodiment, the holding | maintenance part 14 is formed in the 1st division body 11b attached to the vertical frame 3, and the latching | locking part 13 is formed in the 2nd division body 12b.
[0018]
The heating element may be formed in a straight line as indicated by reference numeral 20a in FIG. 5. However, when the electric heater 1 is disposed horizontally, it is desirable to form it in an arch shape as described above in view of stability of the form. . Therefore, when the electric heater 1 is arranged so that the width direction of the heating element 20, in other words, the longitudinal direction of the horizontal frame 2 is oriented vertically, the heating element is formed in a straight line as indicated by reference numeral 20 a. It is desirable.
[0019]
In the third embodiment shown in FIG. 6, unlike the first embodiment, the heating element 20 is formed so as to protrude downward. In this case, the holding part 14 is formed in the 1st division body 11c fixed to the vertical frame 3, and the latching | locking part 13 is formed in the 2nd division body 12c.
[0020]
In the fourth embodiment shown in FIG. 7, unlike the first embodiment, the width direction end portions 22 are bent orthogonally inside the arc formed by the heating element 20, that is, in the present embodiment, downward. A bent portion 23 is formed. Even in the same configuration, the end of the width direction end portion 22 is prevented, but the width of the concealing portion indicated by the symbol W by the second divided body 12d is enlarged, and the heat dissipation efficiency of the heating element 20 is lowered. Therefore, from the viewpoint of heat dissipation efficiency, it is desirable to bend the width direction end portion 22 outside the arc formed by the heating element 20.
[0021]
In the fifth embodiment shown in FIG. 8, unlike the first embodiment, the insulator 10 includes a first divided body 11e having an inverted T-shaped cross section and two plate-shaped second divided bodies 12e. An end 22 in the width direction of the heating element 20 is a hook-shaped bent portion 23, and a pressing portion 14 that 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 a locking portion 13 that locks inside the bent portion 23 and prevents the bent portion 23 from coming off together with the pressing portion 14. The upper end of the second divided body 12 e is fixed by a channel material 17 that penetrates the pin 5.
[0022]
In the fifth embodiment, an inverted bent portion 25 having an extremely smaller radius of curvature than the gentle bend of the intermediate portion of the heating element 20 is formed in the vicinity of the end portion 22 in the width direction. 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 end portions 22 and 22, but the pair of width direction ends. It is desirable to form the heating element 20 between the portions 22 and 22 in a gentle arc shape or linear shape.
[0023]
Reference is made to yet another embodiment of the present invention.
In the above embodiment, the meandering current path is configured by alternately forming the slits 21. However, the form of the slits 21 is not limited to the above-described embodiment, for example, every two slits 21 are formed at intersections, or the slits 21 are fastened to the middle in the width direction of the plate material.
[0024]
In each said embodiment, the flame | frame 2 was comprised with steel materials. However, the frame 2 may be made of a non-combustible material such as ceramic wool.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electric heater with a simple configuration in which the heating element is less likely to fall off the insulator and the heating element is less likely to be violated. As a result, the durability of the electric heater can be improved, the life of manufacturing equipment using the heater can be extended, and the production efficiency can be improved.
[0026]
In addition, the code | symbol entered in the term of the claim is only for the convenience of contrast with drawing, and this invention is not limited to the structure of an accompanying drawing by this entry.
[Brief description of the drawings]
FIG. 1 is a longitudinal 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 in the vicinity of an insulator.
FIG. 4 is a longitudinal sectional view showing the relationship between the insulator and the widthwise end of the heating element.
FIG. 5 is a longitudinal sectional view of an electric heater showing a second embodiment of the present invention.
FIG. 6 is a longitudinal sectional view in the vicinity of an insulator showing a third embodiment of the present invention.
FIG. 7 is a longitudinal sectional view in the vicinity of an insulator showing a fourth embodiment of the present invention.
FIG. 8 is a longitudinal sectional view in the vicinity of an insulator showing a fifth embodiment of the present invention.
FIG. 9 is a longitudinal sectional view in 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 view showing a relationship between thermal expansion / contraction of a heating element and insulators.
[Explanation of symbols]
1: Electric heater, 2: Frame, 3: Vertical frame, 3a: Auxiliary material, 4: Horizontal frame, 5: Fixed pin, 6: Split pin, 10: Insulator, 11a-11e: First divided body, 12a-12e : Second divided body, 13: locking portion, 14: pressing portion, 15: narrow width portion, 16: clearance, 17: channel material, 20: heating element, 21: slit, 22: end in width direction, 23: Bending part, 24: lower surface, 25: inverted bending part, 100: electric heater, 110: insulator, 111: support part, 112: second support part, 120: heating element, 121: slit, 122: end in the width direction

Claims (4)

An electric heater comprising a plate-like heating element in which a current path is formed by forming a slit, and an insulator that supports each of the end portions in the width direction intersecting the slit of the heating element,
The insulator has a locking portion for locking a bent portion formed by bending the width direction end portion and a pressing portion for pressing the width direction end portion, and the locking portion and the pressing portion An electric heater having a width direction end engaged with the insulator.   The electric heater according to claim 1, wherein the heating element is formed in a gentle arc shape or a straight line shape between the pair of width direction end portions.   The electric heater according to claim 1, wherein the heating element is formed in a gentle arc shape between the pair of width direction end portions, and each width direction end portion is bent toward the outside of the arc.   The insulator is divided into first and second divided bodies, and the divided portions are provided with the locking portion and the pressing portion, and the bent portion is allowed to move between the locking portion and the pressing portion. The electric heater according to claim 1, wherein a clearance is provided.

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