1254784 玖、發明說明： 【發明戶斤屬之技術領域3 發明領域 本發明係有關於一種去除附著於封入有可燃性冷媒之 5 冷凍循環之冷卻器之霜的除霜加熱器及該加熱器之製造方 法，該冷卻器係用於冰箱等冷卻裝置。 發明背景 習知用以去除附著於冰箱之冷凍循環之冷卻器的霜之 10 除霜加熱器係揭示於日本專利公開公報特開平8 —54172 號。 第8圖係内藏習知之除霜加熱器15之冰箱1主要部份之 截面圖。冰箱1具有冷凍室2、冷藏室3、冷凍室之門4、冷 藏室之門5、將冷凍室2與冷藏室3分隔之分隔壁6、吸入冷 15 凍室2内之空氣之吸入口 7、吸入冷藏室3内之空氣之吸入口 8、吹出冷氣之吹出口9、蒸發器10、使冷氣循環之風扇11 及將蒸發器10與冷凍室2分隔之分隔壁12。並於蒸發器10之 下方設置以玻璃管包覆呈螺旋狀之鎳鉻耐熱合金線之除霜 加熱器15、用以防止因除霜而產生之水直接滴下而接觸除 20 霜加熱器15時發出之蒸發音之頂板16及金屬製底板17。以 桶13收集之水經由排水口 14而排出。 接著，說明上述除霜加熱器15之動作。蒸發器10為流 經其中之冷媒所冷卻，而將冷;東室2及冷藏室3冷卻。風扇 11將在冷凍室2及冷藏室3升溫之空氣從吸入口 7及吸入口 8 1254784 送至冷卻室（圖中未系）。該空氣在蒸發器ι〇進行熱交換而 被冷卻，並藉風扇I1從吹出口 9送至冷凍室2内。該空氣再 經由從冷凍室2連通多冷藏室3之口（圖中未示）送至冷藏 室3。 5 在蒸發器10進行舞父換之空氣為藉冷凍室2之門4與冷 藏室3之門5的開閉而流入之高溫外部空氣或藉存在於保存 在冷凍室2及冷藏室3么食品所蒸發之水分而呈高濕度之空 氣。因此，於較該交氧低/JZL之蒸發器中，空氣中之水分 便結霜而附著，且隨著結霜量增加， 而阻礙蒸發器10與空 10氣之傳熱。進而，附著之霜成為通風阻礙，而使通過蒸發 器10之空氣量減少，導致熱之通過率下降，而發生冷卻不 足。 因此，在發生冷卻不足前’將除霜加熱器15之鎳鉻耐 熱合金線通電。當鎳絡耐熱合金線一開始通電，便從鎳鉻 15耐熱合金線放射出熱射線至蒸發器及其周圍零件。此時， 放射至底板17之熱射線之一部份從底板17反射至鎳鉻耐熱 合金線，其他之部份則朝向蒸發器10及其周圍零件反射。 朝向蒸發器10反射之熱使附著在蒸發器10、桶13及排水口 14附近之霜融化成水。 20 如此產生之水一部份直接落入桶13，其他則藉頂板16 避開除霜加熱器15而落入桶13後，從排水口 14排出。 在上述習知之除霜加熱器中不僅是鎳鉻耐熱合金線， 用以包含鎳鉻耐熱合金線之玻璃管表面之溫度亦是非常 高。由於底板17位在除霜加熱器15附近，且將從除霜加熱 1254784 器15放射出之熱射線之一部份反射至除霜加熱器15，故玻 璃管之溫度又更上升。 又，冷媒有從蒸發器10或設置於與冰箱連通之部份之 配管漏出之可能性。若冷媒為可燃性時，除霜加熱器15之 5 玻璃管之溫度須不超過冷媒之起火溫度。 【發明内容】 發明概要 一種除霜加熱器，係將附著於冷凍循環之蒸發器之霜 加熱後，將之去除者，其包含有：第1玻璃管，係於一端具 10 有開口者；加熱線，係收納於前述第1玻璃管内者；栓體， 係用以覆蓋前述第1玻璃管之前述開口，並形成有連通前述 第1玻璃管之内部與外部之第1孔者；導線，係通過前述栓 體之前述第1孔，而連接於前述加熱線者；及閥體，係設置 於前述栓體，以使前述第1玻璃管之前述内部之氣體流出至 15 外部者。 在該除霜加熱器中，玻璃管之溫度不易上升。 圖式簡單說明 第1圖係本發明實施形態之除霜加熱器之主要部份截 面圖。 20 第2圖係顯示使用實施形態之除霜加熱器之冰箱之冷 凍系統。 第3圖係實施形態之除霜加熱器之分解圖。 第4圖係顯示另一實施形態之除霜加熱器。 第5圖係顯示又另一實施形態之除霜加熱器。 I254784 第6圖係第5圖所示之除霜加熱器之主要部份截面圖。 第7圖係顯示再另一實施形態之除霜加熱器。 第8圖係具有習知除霜加熱器之冰箱之截面圖。 t實施方式]I 5 較佳實施例之詳細說明 第1圖係本發明第1實施形態之除霜加熱器20之主要部 份截面圖。除霜加熱器2〇内藏電阻線形成螺旋狀之加熱線 21 °加熱線21兩端附近具有直線狀之連接端21&。包覆加熱 線21之玻璃管23呈外徑約i〇.5mm且兩端開口之圓筒狀。包 1〇覆玻璃管23之玻璃管24呈外徑約20mm且兩端開口之圓筒 狀。導線26以導電性襯套28為中介連接於加熱線21。矽膠 製栓體22封住玻璃管23與玻璃管24之開口端。導線26穿過 設置於栓體22之孔22a而連接於加熱線21。於栓體22設置孔 22b ’該孔22b從玻璃管23之内部空間23a或由玻璃管23與玻 15璃管24圍出之空間24a連通栓體22外部。孔22b之最小截面 積在7.1平方毫米以下。橡膠製閥體25安裝於筒27，俾將有 底之筒27之開口部27A堵塞於孔22b。閥體25係作為在預定 之壓力差下僅於一方向開閥之逆止閥。 藉於栓體22以閥體25堵塞預定之孔22b簡單構造，使栓 20 體22之形狀不複雜，而可降低成本。 第2圖顯示使用實施形態之除霜加熱器20之冰箱之冷 床糸統。於由壓縮機60、冷凝器61、減壓機構62及蒸發器 10構成之冷凍循環封入可燃性冷媒，並使之於壓縮機60、 冷;旋^§ 61、減壓機構62及条發為10循ί哀。冷;東循ί辰係用以 8 1254784 冷卻冷卻裝置，諸如設置於冰箱，以冷卻冰箱之冷卻室。 接著，說明如上構成之除霜加熱器20之動作。以藉壓 縮機60之運轉傳送之冷媒冷卻蒸發器10。並藉與壓縮機60 同時作動之風扇11，使冰箱内之空氣通過業經冷卻之蒸發 5器1〇 ’再將與蒸發器1〇進行熱交換後之冷氣吹入冰箱内。 壓縮機60在經過預定之運轉時間後即停止。在停止之同 時，經由導線26，將加熱線21通電，而使除霜加熱器2〇發 熱。 藉加熱線21之發熱，熱射線之一部份直接透射至外 10部，而其他之部份則傳至玻璃管23、玻璃管24，以使玻璃 管24之表面溫度上升至未達可燃性冷媒之起火溫度後，散 熱至外部，以安全地進行蒸發器周圍零件之除霜。 此時，玻璃管23之内部空間23a及由玻璃管23與玻璃管 24圍出之空間24a因溫度之上升而使其内之氣體膨脹。然 15而，由於閥體25因膨脹之空氣而變形，且膨脹之空氣經由 孔22b從閥體25排出至外部，故空間23a與24a之壓力不致上 升，而使玻璃管23與24不致破損，且栓體22不致脫落。 之後，當停止對加熱線21之通電，再度開始冷卻時， 破璃管23與24内部因溫度之降低而減壓。由於在除霜加熱 2〇為20之内部保持減壓之狀態，故閥體25可阻止外部空氣流 入。因此，即使可燃性冷媒存在於除霜加熱器2〇周圍，可 燃性冷媒亦難以流入除霜加熱器2〇内部，因而冷媒著火之 可能性極低。 縱使可燃性冷媒流入玻璃管内部，而因加熱線21而著 1254784 火，閥體25於玻璃管内部達預定壓力以上時，便稍微開啟， 以防止壓力過度上升，但閥體25仍可阻擋火，防止火向外 部蔓延。 又，孔22b之最小截面積為7.1平方毫米，故非常細， 5 因而火無法從其中通過。縱使閥體25脫落，由於火無法通 過孔22b，故火無法蔓延至外部。 閥體25以有底之筒27為中介安裝於栓體22。閥體25為 橡膠製，因而當直接安裝於橡膠製之栓體22時，有閥體25 之位置難以定位，而產生閥體25開啟之壓力之偏差的情 10 形。且閥體25難以直接固定於栓體22。因此，藉閥體25安 裝於以較橡膠硬之材料構成之筒27，可使開閥之壓力穩 定，且筒27可輕易地直接固定於栓體22。由於藉改變筒27 之安裝閥體25之部份的尺寸，可改變開啟閥體25之壓力， 故可依除霜加熱器22之發熱量或玻璃管23、24之内部容積 15 等設定最適合之壓力。 第3圖為除霜加熱器20之分解圖。栓體22之孔22a之直 徑D1小於導線26之直徑D2。因而，栓體22保持在繫緊導線 26之狀態，而使外部空氣或冷媒不致經由孔22a流入除霜加 熱器20内部。 2〇 導線26具有石夕膠等柔軟之被覆層26A，因而不易與孔 22a相通。於導線26之前端安裝襯套28，然後藉使襯套28通 過孔22a，可輕易將導線26插入孔22a。 第4圖係顯示另一實施形態之除霜加熱器12〇。在第1 圖所示之除霜加熱器20中，玻璃管24之表面外側為外露， 10 1254784 而如第4圖所示，亦可以金屬製管50包覆玻璃管24外側。金 屬1官5〇成為玻璃管μ之外圍而可防止水直接流入玻璃管 24 ° 於第5圖顯示另一實施形態之除霜加熱器22〇。第1圖所 5示之除霜加熱器20具有由玻璃管23、24構成之雙層構造， 而除霜加熱器220不具有玻璃管24,而玻璃管23則外露。因 而，只要表面溫度較可燃性冷媒之起火點低，即使只有玻 璃管23，亦可獲得同樣之效果。 第6圖為第5圖所示之除霜加熱器220之主要部份截面 10圖。矽膠製之栓體122封住玻璃管23之開口端。導線26穿過 設置於栓體122之孔122a而連接於加熱線21。於栓體122設 置孔122b，該孔122b係由玻璃管23之内部空間23a連通栓體 122之外部。孔122b之最小截面積在7.1平方毫米以下。橡 膠製閥體25安裝於筒27,俾將有底之筒27之開口部27A堵塞 15住孔〖22b。閥體25係作為在預定之壓力差下僅於一方向開 閥之逆止閥。 第7圖顯示又另一實施形態之除霜加熱器32〇。在第6 圖所示之除霜加熱器220中，玻璃管23之表面外側為外露， 而如第7圖所示，亦可以金屬製管50包覆玻璃管23外側。金 20 屬製管50成為玻璃管23之外圍而可防止水直接流入玻璃管 23 ° 又，在第4圖及第7圖中，若將金屬製管50之表面塗上 黑色，來自金屬管50之輻射熱便增加，而可提高除霜加熱 器120、320之除霜性能。進而，由於可抑制除霜加熱器12〇、 1254784 320之表面溫度上升，故金屬製50管有助於使表面溫度在可 燃性冷媒之起火溫度以下。 又，在實施形態中，以冰箱作為使用除霜加熱器20之 機器作說明，此機器同樣地亦可使用除霜加熱器120、220、 5 320。又，此機器不限於冰箱，亦廣泛地適用於具有蒸發器 之冷卻貯藏庫，具有封入如可燃性冷媒之冷凍循環之或自 動販賣機等。 除霜加熱器係將附著於冷凍循環之蒸發器之霜加熱 後，將之去除。本發明之除霜加熱器具有收納加熱線之玻 10 璃管，且玻璃管之溫度不易上升。因而，即使冷凍循環中 之冷媒為可燃性，玻璃管不致高於冷媒之起火溫度，而無 須考慮抑制溫度之上升。 I：圖式簡單說明3 第1圖係本發明實施形態之除霜加熱器之主要部份截 15 面圖。 第2圖係顯示使用實施形態之除霜加熱器之冰箱之冷 凍系統。 第3圖係實施形態之除霜加熱器之分解圖。 第4圖係顯示另一實施形態之除霜加熱器。 20 第5圖係顯示又另一實施形態之除霜加熱器。 第6圖係第5圖所示之除霜加熱器之主要部份截面圖。 第7圖係顯示再另一實施形態之除霜加熱器。 第8圖係具有習知除霜加熱器之冰箱之截面圖。 12 1254784 【圖式之主要元件代表符號表】 1.. .冰箱 2.. .冷凍室 3.. .冷藏室 4.. .冷凍室之門 5.. .冷藏室之門 6.. .分隔壁 7···吸入口 8.. .吸入口 9.. .吹出口 10.. .蒸發器 11…風扇 12.. .分隔壁 13···桶 14.. .排水口 15.. .除霜加熱器 16.. .頂板 17.. .底板 20.. .除霜加熱器BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting heater for removing a frost attached to a cooler of a 5 refrigeration cycle in which a flammable refrigerant is enclosed, and a heater In the manufacturing method, the cooler is used for a cooling device such as a refrigerator. Background of the Invention A defrosting heater for removing a frost attached to a refrigerator of a refrigerating cycle of a refrigerator is disclosed in Japanese Laid-Open Patent Publication No. Hei 8-54172. Fig. 8 is a cross-sectional view showing the main part of the refrigerator 1 in which the conventional defrosting heater 15 is housed. The refrigerator 1 has a freezing compartment 2, a refrigerating compartment 3, a door 4 of the freezing compartment, a door 5 of the refrigerating compartment, a partition wall 6 separating the freezing compartment 2 from the refrigerating compartment 3, and a suction port 7 for sucking air in the cold freezing compartment 2 The air intake port 8 of the air in the refrigerating compartment 3, the air outlet 9 for blowing out the cold air, the evaporator 10, the fan 11 for circulating the cold air, and the partition wall 12 separating the evaporator 10 from the freezing compartment 2. A defrosting heater 15 is provided under the evaporator 10, which is covered with a spiral tube of a ferrochrome wire. The defrosting heater 15 for preventing the water generated by the defrosting from being directly dripped is contacted with the defrosting heater 15 The top plate 16 and the metal bottom plate 17 of the emitted sound are emitted. The water collected in the tub 13 is discharged through the drain port 14. Next, the operation of the above-described defrosting heater 15 will be described. The evaporator 10 is cooled by the refrigerant flowing therethrough, and is cooled; the east chamber 2 and the refrigerating chamber 3 are cooled. The fan 11 sends the air heated in the freezing compartment 2 and the refrigerating compartment 3 from the suction port 7 and the suction port 8 1254784 to the cooling chamber (not shown). This air is cooled by heat exchange in the evaporator ι, and is sent from the air outlet 9 to the freezing compartment 2 by the fan I1. This air is sent to the refrigerating compartment 3 via a port (not shown) that communicates from the freezing compartment 2 to the multi-refrigeration chamber 3. 5 In the evaporator 10, the air is replaced by the high-temperature outside air that flows in through the opening and closing of the door 4 of the freezing compartment 2 and the door 5 of the refrigerating compartment 3, or is stored in the freezing compartment 2 and the refrigerating compartment 3 Evaporated moisture and high humidity air. Therefore, in the evaporator having a lower oxygen/JZL, the moisture in the air adheres to the frost and adheres, and as the amount of frost increases, the heat transfer between the evaporator 10 and the air is hindered. Further, the adhered frost becomes a ventilation hindrance, and the amount of air passing through the evaporator 10 is reduced, so that the heat passing rate is lowered, and cooling is insufficient. Therefore, the chrome-plated heat resistant alloy wire of the defrosting heater 15 is energized before the occurrence of insufficient cooling. When the nickel-base heat resistant alloy wire is initially energized, heat rays are radiated from the nickel-chromium 15 heat-resistant alloy wire to the evaporator and its surrounding parts. At this time, a part of the heat rays radiated to the bottom plate 17 is reflected from the bottom plate 17 to the nichrome wire, and the other portions are reflected toward the evaporator 10 and its surrounding parts. The heat reflected toward the evaporator 10 causes the frost adhering to the vicinity of the evaporator 10, the tub 13 and the drain port 14 to be melted into water. 20 A portion of the water thus produced falls directly into the tub 13, and the other is discharged from the drain port 14 by the top plate 16 while avoiding the defrosting heater 15 and falling into the tub 13. In the above conventional defrosting heater, not only the nichrome wire but also the temperature of the surface of the glass tube containing the nichrome wire is also very high. Since the bottom plate 17 is located near the defrosting heater 15, and a part of the heat ray radiated from the defrosting heating 1254784 is reflected to the defrosting heater 15, the temperature of the glass tube rises further. Further, the refrigerant may have a possibility of leaking from the evaporator 10 or a piping provided in a portion communicating with the refrigerator. If the refrigerant is flammable, the temperature of the glass tube of the defrosting heater 15 must not exceed the ignition temperature of the refrigerant. SUMMARY OF THE INVENTION A defrosting heater is a method in which a frost adhered to an evaporator of a refrigeration cycle is heated and removed, and includes: a first glass tube, which is provided with an opening at one end; The wire is housed in the first glass tube; the plug body covers the opening of the first glass tube, and is formed with a first hole that communicates with the inside and the outside of the first glass tube; The first hole of the plug body is connected to the heating wire; and the valve body is provided in the plug body such that the gas inside the first glass tube flows out to the outside of the first glass tube. In the defrosting heater, the temperature of the glass tube does not easily rise. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view showing the main part of a defrosting heater according to an embodiment of the present invention. 20 Fig. 2 shows a freezing system of a refrigerator using the defrosting heater of the embodiment. Fig. 3 is an exploded view of the defrosting heater of the embodiment. Fig. 4 is a view showing a defrosting heater of another embodiment. Fig. 5 is a view showing a defrosting heater of still another embodiment. I254784 Fig. 6 is a cross-sectional view of the main part of the defrosting heater shown in Fig. 5. Fig. 7 is a view showing a defrosting heater of still another embodiment. Figure 8 is a cross-sectional view of a refrigerator having a conventional defrosting heater. [Embodiment] I 5 DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig. 1 is a cross-sectional view showing a main part of a defrosting heater 20 according to a first embodiment of the present invention. The defrosting heater 2 has a built-in electric resistance wire to form a spiral heating wire. 21 ° The heating wire 21 has a linear connecting end 21 & The glass tube 23 covering the heating wire 21 has a cylindrical shape having an outer diameter of about i. 5 mm and opening at both ends. The glass tube 24 of the cover glass tube 23 has a cylindrical shape with an outer diameter of about 20 mm and openings at both ends. The wire 26 is connected to the heating wire 21 with the conductive bushing 28 as an intermediary. The silicone body 22 closes the open ends of the glass tube 23 and the glass tube 24. The wire 26 is connected to the heating wire 21 through a hole 22a provided in the plug body 22. The plug 22 is provided with a hole 22b' which communicates with the outside of the plug 22 from the internal space 23a of the glass tube 23 or the space 24a surrounded by the glass tube 23 and the glass tube 24. The smallest cross-sectional area of the hole 22b is 7.1 square millimeters or less. The rubber valve body 25 is attached to the cylinder 27, and the opening 27A of the bottomed cylinder 27 is blocked in the hole 22b. The valve body 25 serves as a check valve that opens only in one direction under a predetermined pressure difference. Since the plug body 22 is simply configured to block the predetermined hole 22b with the valve body 25, the shape of the plug body 22 is not complicated, and the cost can be reduced. Fig. 2 shows a cold bed system of a refrigerator using the defrosting heater 20 of the embodiment. The flammable refrigerant is sealed in a refrigerating cycle including the compressor 60, the condenser 61, the pressure reducing mechanism 62, and the evaporator 10, and is supplied to the compressor 60, cooled, screwed, and the pressure reducing mechanism 62 and the strip are 10 cycles of mourning. Cold; East ί辰 is used for 8 1254784 cooling and cooling devices, such as in the refrigerator to cool the cooling room of the refrigerator. Next, the operation of the defrosting heater 20 configured as above will be described. The evaporator 10 is cooled by the refrigerant transferred by the operation of the compressor 60. The fan 11 which is operated simultaneously with the compressor 60 is used to blow the air in the refrigerator through the cooled evaporator 1 〇 ' and then blow the cold air exchanged with the evaporator 1 吹 into the refrigerator. Compressor 60 is stopped after a predetermined period of operation has elapsed. At the same time of stopping, the heating wire 21 is energized via the wire 26, and the defrosting heater 2 is heated. By the heating of the heating wire 21, one part of the heat ray is directly transmitted to the outer part 10, and the other part is transmitted to the glass tube 23 and the glass tube 24, so that the surface temperature of the glass tube 24 rises to less than flammability. After the ignition temperature of the refrigerant, the heat is radiated to the outside to safely perform defrosting of the parts around the evaporator. At this time, the internal space 23a of the glass tube 23 and the space 24a surrounded by the glass tube 23 and the glass tube 24 are expanded by the temperature rise. However, since the valve body 25 is deformed by the expanded air, and the expanded air is discharged from the valve body 25 to the outside through the hole 22b, the pressure of the spaces 23a and 24a does not rise, and the glass tubes 23 and 24 are not damaged. And the plug 22 does not fall off. Thereafter, when the energization of the heating wire 21 is stopped and the cooling is started again, the inside of the broken glass tubes 23 and 24 is decompressed due to a decrease in temperature. Since the dehumidification heating 2 is maintained in a state of being decompressed inside, the valve body 25 can prevent the outside air from flowing in. Therefore, even if the flammable refrigerant is present around the defrosting heater 2, the flammable refrigerant hardly flows into the defrosting heater 2, and the possibility of the refrigerant igniting is extremely low. Even if the flammable refrigerant flows into the inside of the glass tube and the 1,247,784 fire is caused by the heating wire 21, the valve body 25 is slightly opened when the inside of the glass tube reaches a predetermined pressure or more, so as to prevent the pressure from rising excessively, but the valve body 25 can still block the fire. To prevent fire from spreading to the outside. Further, the smallest cross-sectional area of the hole 22b is 7.1 mm 2 , so it is very thin, so that the fire cannot pass therethrough. Even if the valve body 25 is detached, since the fire cannot pass through the hole 22b, the fire cannot spread to the outside. The valve body 25 is attached to the plug body 22 by means of a bottomed cylinder 27. Since the valve body 25 is made of rubber, when it is directly attached to the rubber body 22, the position of the valve body 25 is difficult to be positioned, and the pressure of the opening of the valve body 25 is generated. Moreover, it is difficult for the valve body 25 to be directly fixed to the plug body 22. Therefore, by the valve body 25 being mounted on the cylinder 27 made of a harder rubber material, the pressure of the valve opening can be stabilized, and the cylinder 27 can be easily fixed directly to the plug body 22. Since the pressure of the valve body 25 can be changed by changing the size of the portion of the cylinder 27 to which the valve body 25 is mounted, the optimum temperature can be set according to the amount of heat generated by the defrosting heater 22 or the internal volume 15 of the glass tubes 23 and 24. The pressure. Fig. 3 is an exploded view of the defrosting heater 20. The diameter D1 of the hole 22a of the plug 22 is smaller than the diameter D2 of the wire 26. Therefore, the plug 22 is held in the state of the tie wire 26, so that the outside air or the refrigerant does not flow into the inside of the defrosting heater 20 via the hole 22a. 2〇 The wire 26 has a soft coating layer 26A such as Shixia, and thus is not easily communicated with the hole 22a. The bushing 28 is mounted at the front end of the wire 26, and then the wire 26 can be easily inserted into the hole 22a by passing the bushing 28 through the hole 22a. Fig. 4 shows a defrosting heater 12A of another embodiment. In the defrosting heater 20 shown in Fig. 1, the outer surface of the glass tube 24 is exposed, 10 1254784. As shown in Fig. 4, the metal tube 50 may be coated on the outer side of the glass tube 24. The metal one is 5 turns into the periphery of the glass tube μ to prevent water from directly flowing into the glass tube. 24 ° The defrosting heater 22 of another embodiment is shown in Fig. 5. The defrosting heater 20 shown in Fig. 1 has a two-layer structure composed of glass tubes 23 and 24, and the defrosting heater 220 does not have the glass tube 24, and the glass tube 23 is exposed. Therefore, as long as the surface temperature is lower than the ignition point of the flammable refrigerant, the same effect can be obtained even if only the glass tube 23 is used. Fig. 6 is a cross-sectional view showing a main portion of the defrosting heater 220 shown in Fig. 5. A plug 122 made of silicone rubber seals the open end of the glass tube 23. The wire 26 is connected to the heating wire 21 through a hole 122a provided in the plug body 122. The plug 122 is provided with a hole 122b which communicates with the outside of the plug body 122 by the internal space 23a of the glass tube 23. The minimum cross-sectional area of the aperture 122b is below 7.1 square millimeters. The rubber valve body 25 is attached to the cylinder 27, and the opening portion 27A of the bottomed cylinder 27 is blocked by 15 holes. The valve body 25 serves as a check valve that opens only in one direction under a predetermined pressure difference. Fig. 7 shows a defrosting heater 32A of still another embodiment. In the defrosting heater 220 shown in Fig. 6, the outer surface of the glass tube 23 is exposed, and as shown in Fig. 7, the metal tube 50 may be coated on the outer side of the glass tube 23. The gold 20 tube 50 becomes the periphery of the glass tube 23 to prevent water from directly flowing into the glass tube 23 °. In FIGS. 4 and 7, if the surface of the metal tube 50 is painted black, the metal tube 50 is provided. The radiant heat is increased, and the defrosting performance of the defrosting heaters 120, 320 can be improved. Further, since the surface temperature rise of the defrosting heaters 12A and 1254784 320 can be suppressed, the metal 50 tube contributes to making the surface temperature lower than the ignition temperature of the flammable refrigerant. Further, in the embodiment, the refrigerator is used as a device using the defrosting heater 20, and the defrosting heaters 120, 220, and 5 320 can be similarly used in the same apparatus. Further, the machine is not limited to a refrigerator, and is also widely applicable to a cooling storage having an evaporator, a refrigerating cycle in which a flammable refrigerant is enclosed, or a vending machine. The defrosting heater removes the frost attached to the evaporator of the refrigeration cycle and heats it. The defrosting heater of the present invention has a glass tube for accommodating a heating wire, and the temperature of the glass tube is not easily increased. Therefore, even if the refrigerant in the refrigeration cycle is flammable, the glass tube is not higher than the ignition temperature of the refrigerant, and it is not necessary to consider the increase in the suppression temperature. I: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a main part of a defrosting heater according to an embodiment of the present invention. Fig. 2 is a view showing a freezing system of a refrigerator using the defrosting heater of the embodiment. Fig. 3 is an exploded view of the defrosting heater of the embodiment. Fig. 4 is a view showing a defrosting heater of another embodiment. 20 Fig. 5 shows a defrosting heater of still another embodiment. Fig. 6 is a cross-sectional view showing the main part of the defrosting heater shown in Fig. 5. Fig. 7 is a view showing a defrosting heater of still another embodiment. Figure 8 is a cross-sectional view of a refrigerator having a conventional defrosting heater. 12 1254784 [The main components of the diagram represent the symbol table] 1.. Refrigerator 2.. Freezer compartment 3.. Refrigeration room 4.. Freezer door 5.. Refrigeration door door 6.. Next wall 7···Intake port 8.. Intake port 9... Blowout port 10.. .Evaporator 11...Fan 12.. partition wall 13···tub 14.....Drainage port 15.. Frost Heater 16.. . Top Plate 17.. . Base Plate 20.. Defrost Heater
21.. .加熱線 21a...連接端 22a...孑 L 22b···孑 L 23.. .玻璃管 23a...内部空間 24.. .玻璃管 24a...空間 25…閥體 26.. .導線 27·..筒 27A...開口部 28…襯套 50.. .金屬製管 60.. .壓縮機 61.. .冷凝器 62.. .減壓機構 120.. .除霜加熱器 122.. .栓體 122a…孑L 122b···孔 220.. .除霜加熱器 22...栓體 320…除霜加熱器 1321.. Heater wire 21a... Connecting end 22a...孑L 22b···孑L 23.. Glass tube 23a...Internal space 24: Glass tube 24a...Space 25...Valve Body 26: Wire 27·.. Tube 27A... Opening 28... Bushing 50.. Metal Tube 60.. Compressor 61.. Condenser 62.. Pressure Reducing Mechanism 120.. Defrost heater 122.. plug body 122a...孑L 122b··· hole 220.. defrosting heater 22...plug body 320...defrost heater 13