JP2014212045A - Planar heating element - Google Patents

Planar heating element Download PDF

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JP2014212045A
JP2014212045A JP2013087982A JP2013087982A JP2014212045A JP 2014212045 A JP2014212045 A JP 2014212045A JP 2013087982 A JP2013087982 A JP 2013087982A JP 2013087982 A JP2013087982 A JP 2013087982A JP 2014212045 A JP2014212045 A JP 2014212045A
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heating element
peripheral edge
inner peripheral
radius
planar heating
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JP6108163B2 (en
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博 藤澤
Hiroshi Fujisawa
博 藤澤
慈 河合
Shigeru Kawai
慈 河合
小林　由和
Yoshikazu Kobayashi
由和 小林
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Creative Technology Corp
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Creative Technology Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater

Abstract

PROBLEM TO BE SOLVED: To provide a planar heating element in which burnout of an insulator is prevented while ensuring in-plane uniformity of temperature, by reducing power concentration on the inner peripheral part at the folded portion of the heating element.SOLUTION: A planar heating element includes an insulator and a heating element. The insulator consists of an insulation sheet, and the heating element is disposed between the insulation sheets. The heating element is formed into a serpentine shape, and has a linear portion 31 and a folded portion 32. The gap width t1 between adjacent linear portions 31, 31 is set narrower than 2 times the width t2 of each linear portion 31. An outer peripheral edge 33 of the folded portion 32 is formed into the shape of a semicircle having radius R2, and the inner peripheral edge 34 is formed into the shape of an arc having a central angle exceeding 180 degrees. The radius R1 of the inner peripheral edge 34 is set in a range of 0.26-0.51 times of the radius R2 of the outer peripheral edge 33.

Description

この発明は、蛇行状の発熱体をポリイミド樹脂等の絶縁体で被覆した構造の面状発熱体に関するものである。   The present invention relates to a planar heating element having a structure in which a meandering heating element is covered with an insulator such as polyimide resin.

従来、この種の技術としては、例えば、特許文献１に記載の面状発熱体がある。
この面状発熱体は、ＳＵＳ等を素材とする帯状の発熱体をポリイミドフィルム上に蛇行状に形成し、別体のポリイミドフィルムをこの発熱体の上に積層した構成を成す。
これにより、所定の電力を発熱体に供給することで、面状発熱体全体を発熱させ、この被加熱物を面状発熱体によって加熱することができる。
通常、このような面状発熱体では、例えば、特許文献２や特許文献３に記載されているように、発熱体のピッチ間を狭くして、電力密度が低くなるように設計する。
これにより、温度の面内均一性を図ると共に、被加熱物と発熱体との温度差を抑制する。 Conventionally, as this type of technology, for example, there is a planar heating element described in Patent Document 1.
This planar heating element has a configuration in which a belt-like heating element made of SUS or the like is formed in a meandering manner on a polyimide film, and a separate polyimide film is laminated on the heating element.
Thereby, by supplying predetermined electric power to the heating element, the entire sheet heating element can generate heat, and the object to be heated can be heated by the sheet heating element.
Normally, such a planar heating element is designed so that the power density is reduced by narrowing the pitch between the heating elements as described in Patent Document 2 and Patent Document 3, for example.
This achieves in-plane uniformity of temperature and suppresses the temperature difference between the object to be heated and the heating element.

特開２００４−０３１１４７号公報JP 2004-031147 A 特開２００４−１８５８９９号公報JP 2004-185899 A 特開２００７−０３５４７５号公報JP 2007-035475 A

しかし、上記した従来の技術では、次のような問題がある。
通常の面状発熱体のデザインにおいては、例えば、特許文献１や特許文献３に記載の面状発熱体のように、発熱体の２つの給電端子が近接するように設計する。
このような面状発熱体の場合、発熱体の折返部が多用されることとなり、電力供給時において、電力集中が、これらの折返部の内周部に発生する。このため、各折返部の内周部の温度が、ポリイミド樹脂等の絶縁体の耐熱温度以上になり、絶縁体が焦げて炭化するという事態が生じるおそれがある。
また、高温の発熱が部分的に発生することで、温度の面内均一性が阻害されるおそれもある。 However, the conventional techniques described above have the following problems.
In the design of an ordinary planar heating element, for example, the two heating terminals of the heating element are designed to be close to each other like the planar heating element described in Patent Document 1 and Patent Document 3.
In the case of such a planar heating element, the folded portions of the heating element are frequently used, and power concentration occurs at the inner peripheral portions of these folded portions during power supply. For this reason, the temperature of the inner peripheral part of each folding | turning part may become more than the heat resistant temperature of insulators, such as a polyimide resin, and there exists a possibility that the insulator may burn and carbonize.
In addition, partial generation of high-temperature heat generation may hinder the in-plane temperature uniformity.

この発明は、上述した課題を解決するためになされたもので、発熱体の折返部内周部の電力集中を低減化することにより、絶縁体の焼損防止と温度の面内均一性の確保とを図った面状発熱体を提供することを目的とする。   The present invention has been made to solve the above-described problems, and by reducing the power concentration in the inner periphery of the folded portion of the heating element, it is possible to prevent the insulator from burning and to ensure the uniformity of the temperature in the surface. An object of the present invention is to provide a planar heating element.

上記課題を解決するために、請求項１の発明は、通電によって発熱する帯状の発熱体を、シート状の絶縁体内に蛇行状に配設して、当該発熱体を、間隙幅ｔ１で平行に隣り合う幅ｔ２の直線部とこれら隣り合う直線部の端部に連結した折返部とで形成した面状発熱体であって、隣り合う直線部の間隙幅ｔ１を、直線部の幅ｔ２の２倍よりも狭く設定し、折返部の外周縁の形状を、隣り合う直線部の外縁の延長線で挟まれる領域内に収まるように形成し、折返部の内周縁の形状を、中心角が１８０度を超える円弧状に形成すると共に、当該内周縁の半径Ｒ１を、隣り合う直線部における外縁間距離Ｗ（＝ｔ１＋２×ｔ２）の半分の０．２６倍〜０．５１倍の範囲内に設定した構成とする。
かかる構成により、帯状の発熱体に通電すると、発熱体が発熱し、その熱が絶縁体を伝搬して、外部に放射される。これにより、被加熱物を絶縁体表面に接触させておくことで、被加熱物を所望の温度に加熱することができる。
ところで、この発熱体では、隣り合う直線部の間隙幅ｔ１が、直線部の幅ｔ２の２倍よりも狭く設定されており、直線部の間隙、つまりピッチが狭い。このため、通電時には、電力集中がこれらの直線部を連結する折返部の内周部に発生し、内周部の温度が、直線部や折返部の外周部に比べて高温になる。この結果、折返部の内周部に位置する絶縁体部分が耐熱温度以上に加熱されることとなり、焦げて炭化するおそれがある。また、このように、高温の発熱が部分的に発生することで、温度の面内均一性が阻害されるおそれがある。
しかし、この発明では、折返部の内周縁の形状を、中心角が１８０度を超える円弧状に形成すると共に、当該内周縁の半径Ｒ１を、隣り合う直線部における外縁間距離Ｗの半分の０．２６倍〜０．５１倍の範囲内に設定しているので、折返部の内周縁の大きさが、直線部の間隙幅ｔ２よりも極めて大きくなっている。このため、折返部の内周部における電力密度が小さくなり、この内周部での電力集中が低減する。この結果、折返部の内周部の温度上昇が抑えられ、内周部に位置する絶縁体部分の焼損を防止することができる。また、折返部の内周部の温度上昇が抑えられるので、温度の面内均一性を確保することができる。 In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a belt-like heating element that generates heat when energized is arranged in a meandering manner in a sheet-like insulator, and the heating element is arranged in parallel with a gap width t1. It is a planar heating element formed by a linear portion having an adjacent width t2 and a folded portion connected to the ends of these adjacent linear portions, and the gap width t1 between the adjacent linear portions is set to 2 of the width t2 of the linear portion. It is set to be narrower than double, and the shape of the outer peripheral edge of the folded portion is formed so as to be within the region sandwiched by the extension line of the outer edge of the adjacent straight portion, and the shape of the inner peripheral edge of the folded portion has a central angle of 180 The radius R1 of the inner peripheral edge is set within a range of 0.26 times to 0.51 times the half of the distance W (= t1 + 2 × t2) between the outer edges in the adjacent straight portions. The configuration is as follows.
With this configuration, when the belt-shaped heating element is energized, the heating element generates heat, and the heat propagates through the insulator and is radiated to the outside. Thereby, a to-be-heated material can be heated to desired temperature by making a to-be-heated material contact the insulator surface.
By the way, in this heating element, the gap width t1 between the adjacent straight portions is set to be narrower than twice the width t2 of the straight portions, and the gap between the straight portions, that is, the pitch is narrow. For this reason, at the time of energization, power concentration occurs in the inner peripheral part of the folded part that connects these linear parts, and the temperature of the inner peripheral part becomes higher than that of the outer peripheral part of the linear part and the folded part. As a result, the insulator part located in the inner peripheral part of the turned-up part is heated to a temperature higher than the heat-resistant temperature, and there is a risk of charring and carbonization. In addition, since the high-temperature heat generation is partially generated in this way, the in-plane temperature uniformity may be hindered.
However, in the present invention, the shape of the inner peripheral edge of the folded portion is formed in an arc shape having a central angle exceeding 180 degrees, and the radius R1 of the inner peripheral edge is set to 0 which is half of the distance W between the outer edges in the adjacent linear portions. Since it is set in the range of .26 times to 0.51 times, the size of the inner peripheral edge of the folded portion is extremely larger than the gap width t2 of the straight portion. For this reason, the electric power density in the inner peripheral part of a folding | returning part becomes small, and the electric power concentration in this inner peripheral part reduces. As a result, the temperature rise in the inner peripheral portion of the folded portion can be suppressed, and burning of the insulator portion located in the inner peripheral portion can be prevented. Moreover, since the temperature rise of the inner peripheral part of a folding | returning part is suppressed, the in-plane uniformity of temperature can be ensured.

請求項２の発明は、請求項１に記載の面状発熱体において、発熱体における折返部の外周縁の形状を、半径Ｒ２の半円状に形成すると共に、当該折返部の内周縁の半径Ｒ１を、半径Ｒ２の０．２６倍〜０．５１倍の範囲内に設定した構成とする。   According to a second aspect of the present invention, in the planar heating element according to the first aspect, the shape of the outer peripheral edge of the folded portion of the heating element is formed in a semicircular shape with a radius R2, and the radius of the inner peripheral edge of the folded portion. R1 is set to be within a range of 0.26 to 0.51 times the radius R2.

請求項３の発明は、請求項１又は請求項２に記載の面状発熱体において、折返部の内周縁の半径Ｒ１を、隣り合う直線部における外縁間距離Ｗの半分の０．３９倍に設定した構成とする。
かかる構成により、発熱体における折返部の内周部の温度上昇を最も低く抑えることができる。 According to a third aspect of the present invention, in the planar heating element according to the first or second aspect, the radius R1 of the inner peripheral edge of the folded portion is set to 0.39 times half the distance W between the outer edges of the adjacent straight portions. The configuration is set.
With this configuration, the temperature rise in the inner peripheral portion of the folded portion of the heat generator can be minimized.

請求項４の発明は、請求項１ないし請求項３のいずれかに記載の面状発熱体において、折返部の内周縁と上記直線部の縁との連結部に面取り部を設けた構成とする。
かかる構成により、他の部分に比べて著しく低温になりがちな連結部の温度を、他の部分の温度に近づけることができる。 According to a fourth aspect of the present invention, in the planar heating element according to any one of the first to third aspects, a chamfered portion is provided at a connecting portion between the inner peripheral edge of the folded portion and the edge of the straight portion. .
With this configuration, the temperature of the connecting portion that tends to be significantly lower than that of other portions can be brought close to the temperature of the other portions.

以上詳しく説明したように、この発明の面状発熱体によれば、発熱体の折返部内周部の電力集中を低減化することができ、この結果、絶縁体の焼損防止と温度の面内均一性の確保とを図ることができるという、優れた効果がある。
特に、請求項３の発明によれば、発熱体における折返部の内周部の温度上昇を最も低く抑えることができるので、より優れた温度の面内均一性を有した面状発熱体を提供することができるという効果がある。
さらに、請求項４の発明によれば、他の部分に比べて著しく低温になりがちな連結部の温度を、他の部分の温度に近づけることができるので、さらに温度の面内均一性を高めることができるという効果がある。 As explained in detail above, according to the planar heating element of the present invention, it is possible to reduce the power concentration in the inner periphery of the folded portion of the heating element. As a result, the insulation is prevented from being burned out and the temperature is uniform in the plane. There is an excellent effect that it is possible to ensure the property.
In particular, according to the invention of claim 3, since the temperature rise of the inner peripheral portion of the folded portion of the heating element can be suppressed to the lowest, a planar heating element having better in-plane uniformity of temperature is provided. There is an effect that can be done.
Furthermore, according to the invention of claim 4, the temperature of the connecting portion, which tends to be significantly lower than other portions, can be brought close to the temperature of the other portions, so that the in-plane uniformity of the temperature is further improved. There is an effect that can be.

この発明の第１実施例に係る面状発熱体を示す分解斜視図である。It is a disassembled perspective view which shows the planar heating element which concerns on 1st Example of this invention. 面状発熱体を一部破断して示す平面図である。It is a top view which shows a planar heating element partly fractured. 図２の矢視Ａ−Ａ断面図である。It is arrow AA sectional drawing of FIG. 直線部と折返部との連結部分を拡大して示す部分拡大平面図である。It is a partial expansion top view which expands and shows the connection part of a linear part and a folding | turning part. 折返部と直線部との連結部における電流密度分布を説明するための平面図である。It is a top view for demonstrating the current density distribution in the connection part of a folding | turning part and a linear part. シミュレーション結果を示す線図である。It is a diagram which shows a simulation result. この発明の第２実施例に係る面状発熱体の要部を示す平面図である。It is a top view which shows the principal part of the planar heating element which concerns on 2nd Example of this invention. 折返部の内周縁と直線部の縁との連結部における電流密度を説明するための平面図である。It is a top view for demonstrating the current density in the connection part of the inner periphery of a folding | turning part, and the edge of a linear part. 発熱体の一変形例を示す部分拡大図である。It is the elements on larger scale which show one modification of a heat generating body.

以下、この発明の最良の形態について図面を参照して説明する。   The best mode of the present invention will be described below with reference to the drawings.

（実施例１）
図１は、この発明の第１実施例に係る面状発熱体を示す分解斜視図であり、図２は、面状発熱体を一部破断して示す平面図であり、図３は、図２の矢視Ａ−Ａ断面図である。
図１に示すように、面状発熱体１は、絶縁体２と、この絶縁体２内に配設された帯状の発熱体３とで構成されている。 Example 1
FIG. 1 is an exploded perspective view showing a planar heating element according to a first embodiment of the present invention, FIG. 2 is a plan view showing the planar heating element in a partially broken state, and FIG. FIG. 2 is a cross-sectional view taken along line AA in FIG.
As shown in FIG. 1, the sheet heating element 1 includes an insulator 2 and a belt-like heating element 3 disposed in the insulator 2.

絶縁体２は、下側の絶縁シート２１と上側の絶縁シート２２とで成る。これら絶縁シート２１，２２は、ポリイミド，ＰＥＴ（ポリエチレンテレフタレート），ＰＥＮ（ポリエチレンナフタレート）やポリアミド等の樹脂を長方形のシート状に成形することにより形成することができる。
また、樹脂の他に、窒化アルミ、アルミナ、マイカ等のセラミックを絶縁体２として用いることができる。この場合にも、樹脂製同様に面内温度均一性を期待することができるが、無機物であるので、異常温度による炭化は発生しない。しかし、クラックや割れ発生の可能性があり、後述する発熱体３を適用することで、クラックや割れ等を抑制することが期待できる。 The insulator 2 includes a lower insulating sheet 21 and an upper insulating sheet 22. These insulating sheets 21 and 22 can be formed by molding a resin such as polyimide, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), or polyamide into a rectangular sheet.
In addition to the resin, ceramics such as aluminum nitride, alumina, and mica can be used as the insulator 2. Even in this case, in-plane temperature uniformity can be expected as in the case of resin, but since it is an inorganic substance, carbonization due to abnormal temperature does not occur. However, there is a possibility of occurrence of cracks and cracks, and it can be expected that cracks and cracks are suppressed by applying the heating element 3 described later.

発熱体３は、通電すると温度が上昇して発熱する導電体であり、例えば、ステンレススチール、ニクロム線（ニッケル−クロム合金）、カンタル、鉄−ニッケル合金、銅−ニッケル合金等を薄い帯状にすることで形成することができる。さらに、導電性インクをスクリーン印刷でパターニングすることでも形成することができる。例えば、絶縁体２として、ポリイミド等の樹脂を使用する場合には、銀インクを樹脂上にスクリーン印刷でパターニングし、窒化アルミ等のセラミックを使用する場合には、白金インクをセラミック上にスクリーン印刷でパターニングすることで、発熱体３を形成するもできる。
この発熱体３は、図３に示すように、絶縁シート２１上に形成されており、絶縁シート２２が、発熱体３を覆うようにして絶縁シート２１上に積層されている。 The heating element 3 is a conductor that generates heat by increasing its temperature when energized. For example, stainless steel, nichrome wire (nickel-chromium alloy), cantal, iron-nickel alloy, copper-nickel alloy, etc. are made into a thin strip. Can be formed. Furthermore, it can also be formed by patterning conductive ink by screen printing. For example, when a resin such as polyimide is used as the insulator 2, silver ink is patterned by screen printing on the resin, and when a ceramic such as aluminum nitride is used, platinum ink is screen printed on the ceramic. The heating element 3 can also be formed by patterning.
As shown in FIG. 3, the heating element 3 is formed on the insulating sheet 21, and the insulating sheet 22 is laminated on the insulating sheet 21 so as to cover the heating element 3.

図２に示すように、発熱体３は、絶縁シート２１上に蛇行状に形成され、その両給電端子３ａ，３ｂが、絶縁体２の外部に露出されている。
ここで、発熱体３について具体的に説明する。
発熱体３は、直線部３１と折返部３２とで成り、折返部３２が、平行に隣り合う直線部３１，３１の端部を連結した蛇行形状を成す。
図４は、直線部３１と折返部３２との連結部分を拡大して示す部分拡大平面図である。
図４に示すように、各直線部３１（３１Ａ，３１Ｂ）の幅はｔ２に設定され、隣り合う直線部３１Ａ，３１Ｂの間隙幅はｔ１に設定されている。そして、この隣り合う直線部３１Ａ，３１Ｂの間隙幅ｔ１は、各直線部３１（３１Ａ，３１Ｂ）の幅ｔ２の２倍よりも狭く設定されている。つまり、直線部３１Ａ，３１Ｂの間隙幅ｔ１は、各直線部３１（３１Ａ，３１Ｂ）の幅ｔ２に比べて狭く設定され、発熱体３による温度の面内均一性の確保が図られている。 As shown in FIG. 2, the heating element 3 is formed in a meandering manner on the insulating sheet 21, and both the power supply terminals 3 a and 3 b are exposed to the outside of the insulator 2.
Here, the heating element 3 will be specifically described.
The heating element 3 includes a straight portion 31 and a folded portion 32, and the folded portion 32 has a meandering shape in which the ends of the straight portions 31, 31 adjacent in parallel are connected.
FIG. 4 is a partially enlarged plan view showing the connecting portion between the straight line portion 31 and the folded portion 32 in an enlarged manner.
As shown in FIG. 4, the width of each linear portion 31 (31A, 31B) is set to t2, and the gap width between the adjacent linear portions 31A, 31B is set to t1. The gap width t1 between the adjacent straight portions 31A and 31B is set to be narrower than twice the width t2 of each straight portion 31 (31A and 31B). That is, the gap width t1 between the straight portions 31A and 31B is set narrower than the width t2 of each straight portion 31 (31A and 31B), and the in-plane uniformity of the temperature by the heating element 3 is ensured.

折返部３２は、外周縁３３と内周縁３４とを有した略Ｃ字状の形状をしている。
折返部３２の外周縁３３は、半径Ｒ２の半円状に形成され、外周縁３３の形状が、隣り合う直線部３１Ａ，３１Ｂの外縁３１ａ，３１ｂの延長線ａ，ｂで挟まれる領域Ｓ内に収まるように設定されている。
一方、内周縁３４は、点Ｏを中心とする中心角が１８０度を超える円弧状に形成され、内周縁３４の半径Ｒ１は、隣り合う直線部３１Ａ，３１Ｂの外縁間距離Ｗ（＝ｔ１＋２×ｔ２）の半分の０．２６倍〜０．５１倍の範囲内に設定されている。つまり、折返部３２の内周縁３４の半径Ｒ１を、外周縁３３の半径Ｒ２の０．２６倍〜０．５１倍の範囲内に設定した。 The folded portion 32 has a substantially C shape having an outer peripheral edge 33 and an inner peripheral edge 34.
The outer peripheral edge 33 of the folded portion 32 is formed in a semicircular shape with a radius R2, and the shape of the outer peripheral edge 33 is in the region S sandwiched between the extension lines a and b of the outer edges 31a and 31b of the adjacent linear portions 31A and 31B. Is set to fit.
On the other hand, the inner peripheral edge 34 is formed in an arc shape with a central angle centered on the point O exceeding 180 degrees, and the radius R1 of the inner peripheral edge 34 is the distance W between the outer edges of the adjacent straight portions 31A and 31B (= t1 + 2 × It is set within the range of 0.26 times to 0.51 times half of t2). That is, the radius R1 of the inner peripheral edge 34 of the folded portion 32 is set in a range of 0.26 to 0.51 times the radius R2 of the outer peripheral edge 33.

次に、この実施例の面状発熱体１の作用及び効果について説明する。
図５は、折返部と直線部との連結部における電流密度分布を説明するための平面図である。
図１〜図３に示した面状発熱体１において、所定の電圧を発熱体３の両給電端子３ａ，３ｂ間に印加し、発熱体に通電すると、温度が上昇して、発熱体３が発熱する。この熱は絶縁体２を伝搬して、絶縁体２の表面から外部に放射される。したがって、図示しない被加熱物を面状発熱体１の絶縁体２表面に接触させておくことで、被加熱物を所望の温度に加熱することができる。 Next, the operation and effect of the sheet heating element 1 of this embodiment will be described.
FIG. 5 is a plan view for explaining the current density distribution in the connecting portion between the folded portion and the straight portion.
In the planar heating element 1 shown in FIGS. 1 to 3, when a predetermined voltage is applied between the feeding terminals 3 a and 3 b of the heating element 3 and the heating element is energized, the temperature rises and the heating element 3 Fever. This heat propagates through the insulator 2 and is radiated to the outside from the surface of the insulator 2. Therefore, the object to be heated can be heated to a desired temperature by bringing the object to be heated (not shown) into contact with the surface of the insulator 2 of the planar heating element 1.

ところで、発熱体３の折返部３２と直線部３１との連結部における電流密度は、内周縁３４を含む内周部が最も高く、その外側にいくに従って、電流密度が低くなっていく。
したがって、従来型の面状発熱体の発熱体では、図５の（ａ）に示すように、内周縁３４が短いため、 電力が、内周縁３４を含む狭い内周部Ｌ１に集中する。この結果、内周部Ｌ１の電流密度が極端に高くなり、その外側の領域Ｌ２，Ｌ３，Ｌ４の電流密度は極めて低くなる。このため、内周部Ｌ１の温度が、他の部分に比べて高温になり、内周部Ｌ１に位置する絶縁体２の部分が耐熱温度以上に加熱され、焦げて炭化するおそれがある。また、このように、高温の発熱が部分的に発生することで、温度の面内均一性が阻害されるおそれがある。 By the way, the current density in the connection part of the folding | returning part 32 and the linear part 31 of the heat generating body 3 is the highest in the inner peripheral part containing the inner peripheral edge 34, and a current density becomes low as it goes to the outer side.
Therefore, in the heating element of the conventional planar heating element, since the inner peripheral edge 34 is short as shown in FIG. 5A, the electric power is concentrated on the narrow inner peripheral portion L1 including the inner peripheral edge 34. As a result, the current density in the inner peripheral portion L1 becomes extremely high, and the current density in the outer regions L2, L3, and L4 becomes extremely low. For this reason, the temperature of the inner peripheral portion L1 becomes higher than that of other portions, and the portion of the insulator 2 located in the inner peripheral portion L1 may be heated to a temperature higher than the heat-resistant temperature, and may be burnt and carbonized. In addition, since the high-temperature heat generation is partially generated in this way, the in-plane temperature uniformity may be hindered.

これに対して、この実施例の面状発熱体１では、図４に示したように、発熱体３の折返部３２において、その内周縁３４が、中心角が１８０度を超える円弧状に形成され、内周縁３４の半径Ｒ１が、外周縁３３の半径Ｒ２の０．２６倍〜０．５１倍の範囲内に設定されており、内周縁３４が長い。このため、図５の（ｂ）に示すように、内周縁３４を含む内周部Ｌ１の広い領域で、電流密度が、上記従来型に比べて低くなり、その外側の領域Ｌ２，Ｌ３，Ｌ４の電流密度も、グラディーションの如く、順次低くなると想定される。
この結果、折返部３２の内周部Ｌ１への電力集中が回避され、内周部Ｌ１の温度上昇が抑えられて、内周部Ｌ１に位置する絶縁体２部分の焼損が防止される。また、内周部Ｌ１の温度上昇が抑えられるので、面状発熱体１全体における温度の面内均一性が確保される。 On the other hand, in the sheet heating element 1 of this embodiment, as shown in FIG. 4, the inner peripheral edge 34 of the folded portion 32 of the heating element 3 is formed in an arc shape whose central angle exceeds 180 degrees. The radius R1 of the inner peripheral edge 34 is set within a range of 0.26 to 0.51 times the radius R2 of the outer peripheral edge 33, and the inner peripheral edge 34 is long. For this reason, as shown in FIG. 5B, the current density is lower in the wide area of the inner peripheral portion L1 including the inner peripheral edge 34 than in the conventional type, and the outer areas L2, L3, L4. It is assumed that the current density also decreases gradually as in the gradient.
As a result, power concentration on the inner peripheral portion L1 of the folded portion 32 is avoided, temperature rise of the inner peripheral portion L1 is suppressed, and burning of the insulator 2 portion located on the inner peripheral portion L1 is prevented. Moreover, since the temperature rise of the inner peripheral part L1 is suppressed, the in-plane uniformity of the temperature in the whole planar heating element 1 is ensured.

発明者は、かかる効果を確認すべく、次のようなシミュレーションを行った。
具体的には、図４に示す発熱体３を、単位長さ当たりの抵抗が３．６Ω／ｍのＳＵＳ（）ステンレススチール）３０４で形成し、その直線部３１の幅ｔ２と厚さを７．４ｍｍと０．０３ｍｍにそれぞれ設定すると共に、間隙幅ｔ１を０．７ｍｍに設定することで、折返部３２の外周縁３３の半径Ｒ２を７．７５ｍｍ設定した。そして、２００Ｖの電圧を両給電端子３ａ，３ｂ間に印加して、８Ａの電流を発熱体３に通電することとした。
かかる条件下で、内周縁３４の半径Ｒ１の外周縁３３の半径Ｒ２に対する倍率を変化させて、各倍率のときの折返部３２の内周部Ｌ１（図５参照）における最大電流密度をシミュレーションした。
図６は、シミュレーション結果を示す線図である。
図６のＰ０点で示すように、内周縁３４の半径Ｒ１の外周縁３３の半径Ｒ２に対する倍率が「０」、即ち、外周縁３３の形状が図５の（ａ）に示した従来型の場合には、内周部の最大電流密度が、１．５×１０８ （Ａ／ｍ２ ）にも達した。
そして、半径Ｒ１の半径Ｒ２に対する倍率を上げていくに従って、最大電流密度は高勾配で低下し、Ｐ３点の「０．３９」倍を境に低勾配で上昇していった。
つまり、半径Ｒ１の半径Ｒ２に対する倍率を「０．２９」倍にすると、図６のＰ１点で示すように、最大電流密度が、１．０×１０８ （Ａ／ｍ２ ）に至り、最大電流密度が、図５の（ａ）に示した従来型の発熱体に対して約４０％も減少した。さらに、倍率を「０．３９」倍迄上げると、図６のＰ３点で示すように、最大電流密度が、０．７１×１０８ （Ａ／ｍ２ ）に至り、最大電流密度が、従来型の発熱体に対して約５３％も減少した。そして、倍率を「０．５１」倍迄上げると、図６のＰ２点で示すように、最大電流密度が、０．７４×１０８ （Ａ／ｍ２ ）に上昇したが、最大電流密度は、従来型の発熱体に対して約５１％も減少していた。
以上のシミュレーションの結果を踏まえ、発明者は、内周縁３４の半径Ｒ１の外周縁３３の半径Ｒ２に対する倍率を０．２６〜０．５１の範囲内（図６のＰ１点からＰ２点内）に設定した。これは、絶縁体２の焼損防止などの見地から、内周部における最大電流密度の低減率が、少なくとも４０％以上必要であること、及び、折返部３２の強度等の面から、折返部３２の幅が、直線部３１の半分程度は必要であることによる。勿論、図６の点Ｐ３で示すように、内周縁３４の半径Ｒ１の外周縁３３の半径Ｒ２に対する倍率を「０．３９」に設定することが、最も好ましい。 The inventor performed the following simulation to confirm the effect.
Specifically, the heating element 3 shown in FIG. 4 is formed of SUS () stainless steel) 304 having a resistance per unit length of 3.6 Ω / m, and the width t2 and thickness of the linear portion 31 are 7. The radius R2 of the outer peripheral edge 33 of the folded portion 32 was set to 7.75 mm by setting each to .4 mm and 0.03 mm and setting the gap width t1 to 0.7 mm. Then, a voltage of 200 V was applied between the power feeding terminals 3a and 3b, and a current of 8A was passed through the heating element 3.
Under such conditions, the maximum current density in the inner peripheral portion L1 (see FIG. 5) of the folded portion 32 at each magnification was simulated by changing the magnification of the radius R1 of the inner peripheral edge 34 with respect to the radius R2 of the outer peripheral edge 33. .
FIG. 6 is a diagram showing simulation results.
As indicated by the point P0 in FIG. 6, the magnification of the radius R1 of the inner peripheral edge 34 with respect to the radius R2 of the outer peripheral edge 33 is “0”, that is, the shape of the outer peripheral edge 33 is the conventional type shown in FIG. In some cases, the maximum current density at the inner periphery reached 1.5 × 10 8 (A / m 2 ).
As the magnification of radius R1 with respect to radius R2 was increased, the maximum current density decreased with a high gradient, and increased with a low gradient at the point of “0.39” times P3.
That is, when the magnification of radius R1 with respect to radius R2 is “0.29” times, the maximum current density reaches 1.0 × 10 8 (A / m 2 ) as shown by point P1 in FIG. The current density was reduced by about 40% compared to the conventional heating element shown in FIG. Further, when the magnification is increased to “0.39” times, the maximum current density reaches 0.71 × 10 8 (A / m 2 ) as shown by the point P3 in FIG. It decreased by about 53% with respect to the heating element of the mold. When the magnification is increased to “0.51” times, the maximum current density increases to 0.74 × 10 8 (A / m 2 ) as shown by point P2 in FIG. This was about 51% lower than that of the conventional heating element.
Based on the results of the above simulation, the inventor sets the magnification of the radius R1 of the inner peripheral edge 34 to the radius R2 of the outer peripheral edge 33 within a range of 0.26 to 0.51 (from the point P1 to the point P2 in FIG. 6). Set. This is because the reduction rate of the maximum current density in the inner peripheral portion is required to be at least 40% from the standpoint of preventing burnout of the insulator 2, and the folded portion 32 from the viewpoint of the strength of the folded portion 32 and the like. This is because about half the width of the straight portion 31 is necessary. Of course, as indicated by a point P3 in FIG. 6, it is most preferable to set the magnification of the radius R1 of the inner peripheral edge 34 to the radius R2 of the outer peripheral edge 33 to “0.39”.

（実施例２）
次に、この発明の第２実施例について説明する。
図７は、この発明の第２実施例に係る面状発熱体の要部を示す平面図であり、図８は、折返部の内周縁と直線部の縁との連結部における電流密度を説明するための平面図である。 (Example 2)
Next explained is the second embodiment of the invention.
FIG. 7 is a plan view showing a main part of a planar heating element according to the second embodiment of the present invention, and FIG. 8 explains the current density at the connecting portion between the inner peripheral edge of the folded portion and the edge of the straight portion. It is a top view for doing.

この実施例の面状発熱体は、図７に示すように、面取り部３５，３６を有する点が、上記第１実施例と異なる。
具体的には、折返部３２の内周縁３４の右端と直線部３１Ａの縁３１ａ’との連結部に面取り部３５を形成し、内周縁３４の左端と直線部３１Ｂの縁３１ｂ’との連結部に面取り部３６を形成した。
図８に示すように、面取り部３５，３６がない発熱体３においては、折返部３２の内周縁３４の右，左端と直線部３１Ａ，３１Ｂとの連結部Ｌ６の電流密度が、他の領域に比べて著しく低くなってしまい、発熱体３の温度の面内均一性を害するおそれがある。
このため、この実施例のように、他の領域に比べて著しく低温になりがちな連結部Ｌ６を削除して、面取り部３５，３６を設けることで、温度の面内均一性を確保することができる。
その他の構成、作用及び効果は、上記第１実施例と同様であるので、それらの記載は省略する。 The planar heating element of this embodiment is different from the first embodiment in that chamfered portions 35 and 36 are provided as shown in FIG.
Specifically, a chamfered portion 35 is formed at the connecting portion between the right end of the inner peripheral edge 34 of the folded portion 32 and the edge 31a ′ of the straight portion 31A, and the left end of the inner peripheral edge 34 and the edge 31b ′ of the straight portion 31B are connected. A chamfered portion 36 was formed in the portion.
As shown in FIG. 8, in the heating element 3 without the chamfered portions 35 and 36, the current density of the connecting portion L6 between the right and left ends of the inner peripheral edge 34 of the folded portion 32 and the straight portions 31A and 31B is different from that of the other region. As a result, the temperature of the heating element 3 may be lowered and the in-plane uniformity of the temperature of the heating element 3 may be impaired.
For this reason, as in this embodiment, the in-plane uniformity of temperature can be ensured by removing the connecting portion L6 that tends to be extremely low in temperature compared to other regions and providing the chamfered portions 35 and 36. Can do.
Since other configurations, operations, and effects are the same as those in the first embodiment, description thereof is omitted.

なお、この発明は、上記実施例に限定されるものではなく、発明の要旨の範囲内において種々の変形や変更が可能である。
例えば、上記第１及び第２実施例では、折返部３２の外周縁３３の形状を半円状にしたが、この外周縁の形状は隣り合う直線部３１Ａ，３１Ｂの外縁３１ａ，３１ｂの延長線ａ，ｂで挟まれる領域Ｓ内に収まるように設定されていればよく、図９に示すように、半円状でない形状の外周縁３３’を有する面状発熱体もこの発明の範囲に含まれることは、勿論である。 In addition, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary of invention.
For example, in the first and second embodiments, the shape of the outer peripheral edge 33 of the folded portion 32 is semicircular, but the shape of this outer peripheral edge is an extension of the outer edges 31a and 31b of the adjacent straight portions 31A and 31B. As long as it is set so as to be within the region S sandwiched between a and b, as shown in FIG. 9, a planar heating element having an outer peripheral edge 33 ′ having a non-circular shape is also included in the scope of the present invention. Of course.

１…面状発熱体、 ２…絶縁体、 ３…発熱体、 ３ａ，３ｂ…給電端子、 ２１，２２…絶縁シート、 ３１，３１Ａ，３１Ｂ…直線部、 ３１ａ，３１ｂ…縁、 ３２…折返部、 ３３，３３’…外周縁、 ３４…内周縁、 ３５，３６…面取り部、 Ｌ１…内周部、 Ｌ２，Ｌ３，Ｌ４…領域、 Ｌ６…連結部。   DESCRIPTION OF SYMBOLS 1 ... Planar heating element, 2 ... Insulator, 3 ... Heating element, 3a, 3b ... Feeding terminal, 21, 22 ... Insulation sheet, 31, 31A, 31B ... Straight part, 31a, 31b ... Edge, 32 ... Folding part 33, 33 ′, outer peripheral edge, 34, inner peripheral edge, 35, 36, chamfered portion, L1, inner peripheral portion, L2, L3, L4, region, L6, connecting portion.

Claims (4)

通電によって発熱する帯状の発熱体を、シート状の絶縁体内に蛇行状に配設して、当該発熱体を、間隙幅ｔ１で平行に隣り合う幅ｔ２の直線部とこれら隣り合う直線部の端部に連結した折返部とで形成した面状発熱体であって、
隣り合う直線部の上記間隙幅ｔ１を、直線部の上記幅ｔ２の２倍よりも狭く設定し、
上記折返部の外周縁の形状を、隣り合う直線部の外縁の延長線で挟まれる領域内に収まるように形成し、
上記折返部の内周縁の形状を、中心角が１８０度を超える円弧状に形成すると共に、当該内周縁の半径Ｒ１を、隣り合う直線部における外縁間距離Ｗ（＝ｔ１＋２×ｔ２）の半分の０．２６倍〜０．５１倍の範囲内に設定した、
ことを特徴とする面状発熱体。 A belt-shaped heating element that generates heat when energized is arranged in a meandering manner in a sheet-like insulator, and the heating element is arranged in parallel with a gap width t1 and adjacent straight line portions of width t2, and ends of these adjacent straight line portions. A planar heating element formed with a folded portion connected to the portion,
The gap width t1 between adjacent straight portions is set to be narrower than twice the width t2 of the straight portions,
The shape of the outer peripheral edge of the folded portion is formed so as to be within the region sandwiched between the extension lines of the outer edges of the adjacent straight portions,
The shape of the inner peripheral edge of the folded portion is formed in an arc shape with a central angle exceeding 180 degrees, and the radius R1 of the inner peripheral edge is half of the distance W (= t1 + 2 × t2) between the outer edges in the adjacent linear portions. Set within the range of 0.26 times to 0.51 times,
A planar heating element characterized by that. 請求項１に記載の面状発熱体において、
上記発熱体における折返部の外周縁の形状を、半径Ｒ２の半円状に形成すると共に、当該折返部の内周縁の半径Ｒ１を、上記半径Ｒ２の０．２６倍〜０．５１倍の範囲内に設定した、
ことを特徴とする面状発熱体。 The planar heating element according to claim 1,
The shape of the outer peripheral edge of the folded part in the heating element is formed in a semicircular shape with a radius R2, and the radius R1 of the inner peripheral edge of the folded part is in the range of 0.26 to 0.51 times the radius R2. Set in
A planar heating element characterized by that. 請求項１又は請求項２に記載の面状発熱体において、
上記折返部の内周縁の半径Ｒ１を、隣り合う直線部における上記外縁間距離Ｗの半分の０．３９倍に設定した、
ことを特徴とする面状発熱体。 In the planar heating element according to claim 1 or 2,
The radius R1 of the inner periphery of the folded portion is set to 0.39 times half of the distance W between the outer edges in the adjacent straight portions,
A planar heating element characterized by that. 請求項１ないし請求項３のいずれかに記載の面状発熱体において、
上記折返部の内周縁と上記直線部の縁との連結部に面取り部を設けた、
ことを特徴とする面状発熱体。 The planar heating element according to any one of claims 1 to 3,
A chamfered portion was provided at the connecting portion between the inner peripheral edge of the folded portion and the edge of the linear portion,
A planar heating element characterized by that.
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WO2023275949A1 (en) * 2021-06-28 2023-01-05 日本たばこ産業株式会社 Aerosol generation system

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JPS53144544U (en) * 1977-04-21 1978-11-14
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WO2016192714A1 (en) * 2015-05-30 2016-12-08 Webasto SE Electric heating device for mobile applications
CN107771411A (en) * 2015-05-30 2018-03-06 韦巴斯托股份公司 Electric heater unit for Mobile solution
JP2018516198A (en) * 2015-05-30 2018-06-21 ベバスト エスエーＷｅｂａｓｔｏ ＳＥ Electric heating device for mobile applications
CN107771411B (en) * 2015-05-30 2019-04-19 韦巴斯托股份公司 Electric heater unit for mobile application
US10314114B2 (en) 2015-05-30 2019-06-04 Webasto SE Electric heating device for mobile applications
WO2023275948A1 (en) * 2021-06-28 2023-01-05 日本たばこ産業株式会社 Aerosol generation system
WO2023275949A1 (en) * 2021-06-28 2023-01-05 日本たばこ産業株式会社 Aerosol generation system

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