1247851 (1) 玖、發明說明 【發明所屬之技術領域】 本發明是關於密閉型兩段壓縮式壓縮機，特別是關於 謀求設在球關節式活塞（ball joint type piston)之球（ ball )與球座間的緩衝環（buffer ring )之改良的密閉型 兩段壓縮式壓縮機。 【先前技術】 對於往復型壓縮機（reciprocal type compressor)之 設在球關節式活塞之球部與球座間之緩衝環（buffer ring )，使用耐潛變性（c r e e p r e s i s t a n c e )或耐磨損性稍低但 摩擦係數小之聚四氟^乙嫌樹脂（polytetrafluoroethylene resin ;以下簡稱爲PTFE)的單獨聚合體。這是如第7圖所 示，以往的1段壓縮式往復型壓縮機（single-compression type reciprocal type compressor) 61 是由於以具有壓縮前 的低壓力PL之吸入氣體（suction gas )充滿於密閉盒（ sealed case) 2內，故在壓縮衝程時，藉由施壓於面臨壓 縮室31d內的活塞（piston) 32的前面32a之壓縮的大壓力 與施壓於面臨密閉盒2內的活塞32的背面32b之低壓力PL 的吸入氣體壓力之差壓，將活塞32按壓於連桿（ connecting rod) 33的前端之球部33a，使得大的力量施壓 於其體部33a。相對於此，在吸入衝程時，雖壓縮室31d 內的壓力受到吸氣氣體的通路阻抗等會較密閉盒2內的壓 力下降稍許的壓抑dP，但由於施加於活塞32的前面32a與 (2) 1247851 背面3 2b之壓力的壓力差極小，不會有大的壓力施加於球 部33a，使得大的壓力不會施加於緩衝環340，故即使是柔 軟且容易變形之PTFE也可使用。 相對於此，如第8圖所示，在兩段壓縮式往復型壓縮 機(double-compression type reciprocal type compressor )62，於受到密閉盒2內的壓力之影響，以具有在低壓段 壓縮的中間壓PM之流出氣體（discharge gas )充滿密閉 盒2內的情況；或以在第2壓縮部所壓縮的高壓之流出氣體 所充滿之情況時，吸氣氣體的壓力PL在形成較密閉盒內 部的氣體之壓力低的情況下，當吸入衝程時，藉由施壓於 活塞32的前面32a之壓力與施加於背面32b之壓力的差壓 (負荷）（PM + dP-PL)，將球部33a按壓於緩衝環340。 由於無法將充分的潤滑油供給至該緩衝環340，故當將 PTFE使用於緩衝環340時，緩衝環340變得容易磨損。又 ，在重負荷運轉或運轉開始時之過大的負荷狀態時，在緩 衝環340容易產生潛變（creep )。因此，PTFE製的緩衝 環340耐久性差且可靠性低。 又，在活塞的球部與球座間設置襯墊（packing )的 結構之球關節式活塞壓縮機是如日本特開平3- 130585號公 報第2頁下段右欄第16行〜第3頁左欄第5行及第2圖、與日 本特開2003-8 3 247號公報段落【1045】及第4圖所揭示。 但，該襯墊也容易磨損，又在重負荷運轉或運轉開始時之 過大的負荷狀態時，在緩衝環340容易產生潛變。因此， 設有襯墊的結構之球關節式活塞壓縮機也是耐久性差且可 -6 - (3) 1247851 靠性低。 【發明內容】 [發明所欲解決之課題] 本發明是爲了解決上述情事而開發完成的發明，其目 的在於提供一種即使在重負荷運轉或運轉開始時之過大的 負荷狀態的運轉時，緩衝環的磨損或沉降（settling )也 少，耐久性優良，具有高度可靠性及高性能之密閉型兩段 壓縮式壓縮機。 [用以解決課題之手段] 爲了達到上述目的，若根據本發明的一個形態的話， 可提供一種：密閉型兩段壓縮式壓縮機，是將吸入冷媒成 爲第1階段的壓縮而噴出之第1壓縮部、與吸入由該第1壓 縮部噴出的冷媒後成爲第2階段之壓縮而噴出之第2壓縮部 收納於密閉盒內，第1壓縮部與第2壓縮部分別具有球關節 式活塞，前述密閉盒內形成：由第1壓縮部所噴出的冷媒 所具有之中間壓狀態及由第2壓縮部所噴出的冷媒所具有 之高壓狀態的其中一者之密閉型兩段壓縮式壓縮機，其特 徵爲：至少設置於前述第1壓縮部的球關節式活塞之球部 與球座間之緩衝環是以具有全氟烷氧基（perfluoroalkoxy group )之聚四氟乙烯樹脂構成。藉此，能夠達到：即使 在重負荷運轉或運轉開始時之過大的負荷狀態下，緩衝環 的磨損或沉降少，耐久性優良，具有高度可靠性及高性能 (4) !247851 之密閉型兩段壓縮式壓縮機。 又，若根據本發明的其他形態的話，可提供一種：密 閉型兩段壓縮式壓縮機，是將吸入冷媒成爲第1階段的壓 縮而噴出之第1壓縮部、與吸入由該第1壓縮部噴出的冷媒 後成爲第2階段之壓縮而噴出之第2壓縮部收納於密閉盒內 ，第1壓縮部與第2壓縮部分別具有球關節式活塞，前述密 閉盒內形成：由第1壓縮部所噴出的冷媒所具有之中間壓 狀態及由第2壓縮部所噴出的冷媒所具有之高壓狀態的其 中一者之密閉型兩段壓縮式壓縮機，其特徵爲：至少設置 於前述第1壓縮部的球關節式活塞之球部與球座間之緩衝 環是以交聯聚四氟乙烯樹脂 （bridged polytetrafluoroethylene resin)構成的。藉此可達到··即 使在重負荷運轉或運轉開始時之過大的負荷狀態下，緩衝 環的磨損或沉降少，耐久性優良，具有高度可靠性及高性 能之密閉型兩段壓縮式壓縮機。 [發明效果] 若根據本發明之密閉型兩段壓縮式壓縮機的話，能夠 提供即使在重負荷運轉或運轉開始時之過大的負荷狀態下 ’緩衝環的磨損或沉降少，耐久性優良，具有高度可靠性 及高性能之密閉型兩段壓縮式壓縮機。 【實施方式】 以下，參照圖面說明關於本發明之密閉型兩段壓縮式 -8 - (5) 1247851 壓縮機的一實施形態。 第1圖是本發明之密閉型兩段壓縮式壓縮機的縱斷面 圖，第2圖是其橫斷面圖。 如第1及第2圖所示，本發明之密閉型兩段壓縮式壓縮 機1是具有密閉盒2 ;在該密閉盒2內吸入冷媒進行第1階段 的壓縮之第1壓縮部3及吸入由該第1壓縮部3縮壓噴出的冷 媒進行第2階段的壓縮之第2壓縮部4 ;及驅動第1壓縮部3 及第2壓縮部4之電動機部5，第1壓縮部3是將經由設置在 密閉盒2的吸入管2a由例如冷藏庫的冷凍室用蒸發器所吸 入的低壓冷媒壓縮成中間壓後噴出至密閉盒2內，將噴出 至密閉盒2內的中間壓之冷媒及經由中間壓吸入管2c由冷 藏庫的冷藏室用蒸發器所吸入的中間壓之冷媒吸入至第2 壓縮部4，壓縮成高壓後經由噴出管2b噴出至機體外。 在安裝於電動機部5的上方之框架（frame ) 6，將第1 壓縮部3及第2壓縮部4形成一體。 第1壓縮部3是具有：設有具備吸入口 31a及噴出口 31b 的壓缸（cylinder) 31c 之缸體（cylinder block) 31 ; 在壓缸31c內形成壓縮室31d地往復移動於壓缸31c內之 活塞32 ;及藉由球關節（ball joint )來連結該活塞32與曲 柄軸（crank shaft ) 51之連桿33。在該連桿33的一端形 成有球關節之球部33a，該球部可動地嵌合於設在活塞32 的背面32b之球座32c，在另一端形成有筒狀結合部33b， 該結合部可供曲柄軸51的曲柄部（crank portion ) 5 la自 由旋轉地嵌合。且，如第3圖所示，在活塞32的球座32c (6) 1247851 與連桿3 3的球部3 3 a之間設有緩衝環3 4。 該緩衝環34是以具有全氟烷氧基之PTFE或交聯 PTFE所構成的。 雖具有全氟烷氧基之PTFE的摩擦係數較PTFE大’ 但耐潛變性及耐磨損性高。因此，以具有全氟烷氧基之 PTFE構成的緩衝環是即使在重負荷運轉或運轉開始時之 過大的負荷狀態下，緩衝環的磨損或沉降少’壓縮機是耐 久性優良，且具有高可靠性及高性能。 又，交聯PTFE之比磨損量大約是PTFE的1/104 ( mm 3/N - m )，潛變之發生降至大約1/2。因此，使用以交聯 PTFE所構成的緩衝環之壓縮機是即使在伴隨有振動之高 負荷也可進行穩定的運轉，提昇可靠性，並且摩擦係數雖 較PTFE大但其本身極小，所以不會有使摩擦阻抗增加， 可維持壓縮機之高效率。 又，在使用於緩衝環34的具有全氟烷氧基之PTFE或 交聯PTFE使含有10重量％以下之玻璃纖維（glass fiber ) 或碳纖維（carbon fiber )爲佳，更理想爲5重量％。藉由 作成1〇重量％以下可獲得高度的可靠性。在加入玻璃纖維 或碳纖維的具有全氟烷氧基之PTFE的單個磨損滑動試驗 ，證明了 ：能夠抑制成PTFE的大約1/2之磨損量，在組裝 於壓縮機的情況時，即使在重負荷運轉或運轉開始時之過 大的負荷量狀態之下，緩衝環的磨損或沉降少。由於藉由 將塡充量作成10重量％以下，不需要將材料的彈性係數極 端地提昇即可’故不需要強力地塡隙（caulk )球座，以 -10- (7) 1247851 與以往的PTFE相同時間的插入運轉能使緩衝環與球部適 應，能以短的插入運轉獲得預定的性能，達到省能源（ energy-saving)。再者，當玻璃纖維或碳纖維的塡充量超 過10重量％時，緩衝環之磨損量增加。又，由於其彈性也 變高，故需要強力地塡隙球座，比起以往的PTFE，需要 更長的時間使緩衝環與球部適應。 又，含有10重量％以下的玻璃纖維或碳纖維之具有全 氟烷氧基的PTFE或交聯PTFE是由於具有優良的耐磨損 性，故即使以稍許的潤滑油，亦可確保高度的可靠性，又 減低與球部之滑動損失，提昇運轉效率。 且，藉由將緩衝環之壓縮彈性率作成lOOOMPa以下， 能夠以小的力量塡隙球座，使緩衝環密著於球面。因此， 能夠減低緩衝環與球部之間的滑動損失。當緩衝環的壓縮 彈性率超過1000 MPa時，由於爲了使緩衝環密著於球部， 而必須使用大的塡隙力，使得上述滑動損失變大’故運轉 效率降低。又，當塡隙球座時，緩衝環與球部之密著性差 則由於緩衝環與球部間產生間隙，形成局部性地接觸’故 這些之間的滑動損失增大。又，受到該間隙的存在’在球 部與緩衝環之間產生所謂的游移，使得活塞運動變得不穩 定。在極端之情況時，也會有球部由球座脫離’變得無法 壓縮。因此，藉由將緩衝環的壓縮彈性率作成1000MPa以 下，能夠以小的塡隙力使緩衝環密著於球面’故能夠防止 局部性的磨損，可確保高度之可靠性。 又，第2壓縮部4是具有與第1壓縮部3相同之構造’對 -11- (8) 1247851 於第1壓縮部3與曲柄軸51呈軸對稱地配置。第2壓縮部4是 具有：設有具備吸入口 41a及噴出口 41b的壓缸41c之缸 體41 ;在壓缸41c內形成壓縮室41d地往復移動之活塞42 ;及連結該活塞42與曲柄軸51之連桿43。在連桿43的其中 一端形成有球部43a，該球部可動地嵌合於設在活塞42之 球座42c，在另一端，形成有筒狀的結合部43b，該結合部 可旋轉自如地外嵌於第1壓縮部3的連桿33之結合部33b ’ 具有可供連桿33搖動之空隙部。 且，在活塞42的球座42c與連桿43的球部43a之間設 有緩衝環44，該緩衝環44是以具有全氟烷氧基之PTFE或 交聯PTFE所構成的。在圖中，所賦予的圖號2c是指中間 壓冷媒吸入管。 其次，說明關於使用本發明之密閉型兩段壓縮式壓縮 機的冷媒之壓縮方法。 在如第1及第2圖所示的結構，在曲柄軸51朝逆時鐘方 向旋轉的情況時，在活塞32由上死點朝下死點移動之吸入 衝程，冷媒氣體被吸入至壓縮室31d。此時，冷媒氣體是 經由吸入管2a後經由第1壓縮部3的吸入口 31a吸入至壓縮 室3 Id。在活塞32由下死點朝上死點移動之壓縮衝程，該 冷媒氣體被壓縮成中間壓PM後噴出至密閉盒2內。 如第5圖所示，在上述第1壓縮部3的吸入衝程，因由 冷凍循環至壓縮室3 1 d之通路阻抗，使得吸入至壓縮室 3 1 d的冷媒氣體之壓力是形成僅較冷凍循環內的冷媒氣體 壓力PL降低通路阻抗部分的壓力dP之壓力（PL-dP )。 -12· 1247851 Ο) 再者，在冷媒以液體狀態由冷凍循環返回之情況時’該通 路阻抗部分的壓力dP變得非常大。 因在第1壓縮部3的吸入衝程，壓力（PL-dP )施加於 活塞32的前面32a，而密閉盒2內的冷媒所具有的中間壓 PM施加在面臨密閉盒2內的活塞32之背面32b，所以作用 於活塞32之差壓（負荷）形成（PM + dP-PL)。藉由該差 壓（PM + dP-PL )，使得活塞32承受朝向上死點的拉引力 。因該拉引力除了（ PM + dP-PL)之外、加上活塞32與壓 缸3 1c間之滑動損失更加上作用於活塞32之慣性力（在實 驗，超過lOkgf的力量作用），使得活塞32在上死點方向 (第2圖的右方向）承受力量，使曲柄軸51朝逆時鐘方向 旋轉時，曲柄軸51朝第2圖中左方向動作，故球部33a與 緩衝環34被按壓。並且，由於曲柄軸51進行偏心運動，故 球部33a伴隨該偏心運動，進行旋轉運動。 由於上述差壓（PM + dP-PL )是在壓縮機的運轉開始 時等之過度運轉時變大，故施加於緩衝環34之負荷變大。 且，由於施加有差壓（PM + dP-PL )、滑動阻抗及慣性力 ，故大的負荷施加於緩衝環34。 因此，緩衝環34是在與進行旋轉運動之球部33a滑動 之狀態下承受負荷，故需要能承受負荷。且，緩衝環34是 由於在冷媒壓縮時壓縮室3 1 d內的冷媒形成高溫，使得活 塞3 2也形成高溫，故需要具有優良之耐熱性。又，由於緩 衝環34是塡隙活塞32之球座32c而連結，故被要求具有預 定的彈性。因此，在緩衝環須要可滿足上述耐熱性及彈性 -13- (10) 1247851 要求之具有全氟烷氧基之PTFE或交聯PTFE。藉由使用 其中任一者，可減少緩衝環之磨損或沉降。因此，壓縮機 能提昇耐久性，可增加可靠性及性能。 且，如第6圖所示，針對第2壓縮部4，由於在吸入衝 程，吸入密閉盒2內之具有中間壓PM的冷媒氣體，故壓 縮室41d的吸入壓力僅降低通路阻抗壓力dP，形成（PM-dP )，壓力（PM-dP )施加於活塞42的前面42a，中間壓 PM施加於活塞42的背面42b，作用於活塞42之力量（負荷 )是僅形成因吸入阻抗所引起之壓力dP，不會有大的負 荷施加於其上。 因此，第2壓縮部4之緩衝環44是並非一定須要以具有 全氟烷氧基之PTFE或交聯PTFE所構成，亦能以與以往 的緩衝環同樣地以單獨聚合體的PTFE所構成。 再者，在第2壓縮部4的吸入衝程，雖有活塞的慣性力 變大之情事，但因慣性力是受活塞的質量、速度等所影響 ，所以第2壓縮部4是在壓縮負荷變大之情況時，須要保持 強度使得不會產生因壓縮所引起之變形等，在此情況，會 有將活塞的壁厚作厚等之增加質量的傾向。由於慣性力與 質量成比例，故施加於緩衝環之負荷增加。因此，在此情 況時，第2壓縮部之緩衝環也與上述第1壓縮部的緩衝環同 樣地，以具有全氟烷氧基之PTFE或交聯PTFE來構成爲 佳。 其中，並不需要將第2壓縮部及第1壓縮部的緩衝環作 成相同特性。在使兩者具有不同之特性的情況時，預先作 -14- (11) 1247851 成能以顏色分辨兩者的話，在組裝時能夠防止取錯，非常 便利。又，因應第1壓縮部的壓縮及第2壓縮部之壓縮比， 能夠適宜地設定第1壓縮部的壓缸膛（cylinder bore )及 第1壓縮部的壓缸膛之規格。 若根據上述之本實施形態的密閉型兩段壓縮式壓縮機 的話，雖藉由密閉盒內的中間壓或高壓之冷媒氣體，使得 在第1壓縮部的活塞施加大的負荷，且也施加有滑動阻抗 、慣性力，但因緩衝環是以具有全氟烷氧基之PTFE或交 聯PTFE所構成，所以即使在重負荷運轉或高溫度的運轉 時，也能減少緩衝環之磨損或沉降。因此，壓縮機可提升 耐久性，且增加可靠性及性能。 又，因緩衝環是含有10重量％以下之玻璃纖維或碳纖 維，所以塡隙球座時，能以小的力量將其密著於球部，即 使在剛組裝完成後進行運轉時，也能以緩衝環的面支承負 荷，可減少面壓，且，因緩衝環之壓縮彈性率爲1000MPa 以下，所以能夠以小的塡隙力將其密著於球部，故能夠防 止局部性的磨損，可保持高度之可靠性。 【圖式簡單說明】 第1圖是本發明之密閉型兩段壓縮式壓縮機的一實施 形態之縱斷面圖。 第2圖是本發明之密閉型兩段壓縮式壓縮機的一實施 形態之橫斷面圖。 第3圖是本發明之密閉型兩段壓縮式壓縮機的一實施 -15· 1247851 (12) 形態的活塞部分之縱斷面圖。 第4圖是第3圖的A-A視角之斷面圖。 第5圖是顯示本發明之密閉型兩段壓縮式壓縮機的一 實施形態的第1壓縮部之吸入形成的縱斷面圖。 第6圖是顯示本發明之密閉型兩段壓縮式壓縮機的一 實施形態的第2壓縮部之吸入形成的縱斷面圖。 第7圖是顯示以往之密閉型兩段壓縮式壓縮機的一實 施形態的第1壓縮部之吸入形成的縱斷面圖。 第8圖是顯示以往之密閉型兩段壓縮式壓縮機的一實 施形態的第2壓縮部之吸入形成的縱斷面圖。 【主要元件符號說明】 1…密閉型兩段壓縮式壓縮機 2…密閉盒 3…第1壓縮部 4…第2壓縮部 5…電動機部 32…活塞 32c…球座 33…連桿1247851 (1) Field of the Invention The present invention relates to a hermetic two-stage compression type compressor, and more particularly to a ball (ball) which is provided in a ball joint type piston. An improved hermetic two-stage compression compressor with a buffer ring between the seats. [Prior Art] For a reciprocal type compressor, a buffer ring provided between a ball portion of a ball joint piston and a ball seat is slightly less resistant to creep resistance or wear resistance. A single polymer of polytetrafluoroethylene resin (hereinafter abbreviated as PTFE) having a small coefficient of friction. This is shown in Fig. 7. The conventional single-compression type reciprocal type compressor 61 is filled in a closed box by a suction gas having a low pressure PL before compression. In the case of the sealed case 2, the pressure is applied to the piston 32 facing the inside of the sealed casing 2 by the large pressure of compression applied to the front face 32a of the piston 32 facing the compression chamber 31d during the compression stroke. The differential pressure of the suction gas pressure of the low pressure PL of the back surface 32b presses the piston 32 against the ball portion 33a of the front end of the connecting rod 33, so that a large force is applied to the body portion 33a. On the other hand, in the suction stroke, the pressure in the compression chamber 31d is slightly suppressed by the pressure in the closed casing 2 due to the passage impedance of the intake air, but is applied to the front faces 32a and (2 of the piston 32). 1247851 The pressure difference of the pressure of the back surface 3 2b is extremely small, and no large pressure is applied to the ball portion 33a, so that a large pressure is not applied to the buffer ring 340, so that even a soft and easily deformable PTFE can be used. On the other hand, as shown in Fig. 8, the double-compression type reciprocal type compressor 62 is subjected to the pressure in the sealed casing 2 to have the compression in the low pressure section. When the discharge gas of the PM is filled in the sealed casing 2; or when the high-pressure outflow gas compressed by the second compression portion is filled, the pressure PL of the intake gas is formed inside the relatively closed casing. When the pressure of the gas is low, the ball portion 33a is pressed by the differential pressure (load) (PM + dP - PL) applied to the front surface 32a of the piston 32 and the pressure applied to the back surface 32b at the suction stroke. Pressed on the buffer ring 340. Since sufficient lubricating oil cannot be supplied to the buffer ring 340, when the PTFE is used for the buffer ring 340, the buffer ring 340 becomes easily worn. Further, in the case of an excessive load state at the time of heavy load operation or operation start, the buffer ring 340 is liable to generate creep. Therefore, the PTFE-made cushion ring 340 has poor durability and low reliability. Further, the ball joint type piston compressor having a packing between the ball portion and the ball seat of the piston is the lower column of the right column of the second page of the second page of the Japanese Patent Laid-Open No. 3-130585. Lines 5 and 2, and paragraphs [1045] and 4 of Japanese Laid-Open Patent Publication No. 2003-8 3 247. However, the spacer is also prone to wear, and the creeping ring 340 is liable to cause creep in the excessive load state at the time of heavy load operation or operation start. Therefore, the ball joint piston compressor having a gasket structure is also poor in durability and can be low in -6 - (3) 1247851. [Problem to be Solved by the Invention] The present invention has been developed in order to solve the above-described problems, and an object of the invention is to provide a buffer ring even in an operation in an excessive load state at the time of heavy load operation or operation start. A closed two-stage compression compressor with low wear and settling, excellent durability, and high reliability and high performance. [Means for Solving the Problem] In order to achieve the above object, according to one aspect of the present invention, it is possible to provide a sealed two-stage compression type compressor which is the first to be squeezed by the suction refrigerant. The compression unit and the second compression unit that is compressed in the second stage after being sucked into the refrigerant discharged from the first compression unit are stored in the sealed casing, and the first compression unit and the second compression unit each have a ball joint type piston. The sealed type two-stage compression type compressor in which one of the intermediate pressure state of the refrigerant discharged from the first compression unit and the high pressure state of the refrigerant discharged from the second compression unit is formed in the sealed casing, It is characterized in that at least the buffer ring between the ball portion of the ball joint piston and the ball seat provided in the first compression portion is made of a polytetrafluoroethylene resin having a perfluoroalkoxy group. As a result, it is possible to achieve a low degree of wear and a low degree of durability of the buffer ring even in an excessive load state during heavy load operation or operation start, and high reliability and high performance (4) !247851 Segment compression compressor. Moreover, according to another aspect of the present invention, a sealed two-stage compression type compressor is provided, which is a first compression unit that discharges the suction refrigerant into a first-stage compression, and is sucked by the first compression unit. After the discharged refrigerant is compressed in the second stage, the second compressed portion that is ejected is stored in the sealed casing, and the first compressed portion and the second compressed portion each have a ball joint type piston, and the sealed portion is formed by the first compressing portion. A sealed two-stage compression type compressor in which an intermediate pressure state of a refrigerant to be discharged and a high pressure state of a refrigerant discharged from a second compression unit are at least provided in the first compression The buffer ring between the ball portion of the ball joint piston and the ball seat is composed of bridged polytetrafluoroethylene resin. This makes it possible to achieve a closed-type two-stage compression type compressor with high reliability and high performance, even in an excessive load state at the time of heavy load operation or operation, with less wear or settlement of the buffer ring, excellent durability, and high reliability. . [Effect of the Invention] According to the sealed two-stage compression type compressor of the present invention, it is possible to provide a small number of wear and settlement of the buffer ring even in an excessive load state at the time of heavy load operation or operation start, and it is excellent in durability. Highly reliable and high performance closed two-stage compression compressor. [Embodiment] Hereinafter, an embodiment of a sealed two-stage compression type -8 - (5) 1247851 compressor according to the present invention will be described with reference to the drawings. Fig. 1 is a longitudinal sectional view of a hermetic two-stage compression type compressor of the present invention, and Fig. 2 is a cross-sectional view thereof. As shown in the first and second figures, the sealed two-stage compression type compressor 1 of the present invention has a sealed casing 2, and the first compression unit 3 that sucks the refrigerant in the sealed casing 2 to perform the first stage of compression and suction. The second compression unit 4 that compresses the second stage by the refrigerant compressed and contracted by the first compression unit 3, and the motor unit 5 that drives the first compression unit 3 and the second compression unit 4, the first compression unit 3 The low-pressure refrigerant sucked by the evaporator in the freezer compartment of the refrigerator is compressed into an intermediate pressure via the suction pipe 2a provided in the sealed casing 2, and then discharged into the sealed casing 2, and the intermediate refrigerant discharged into the sealed casing 2 and the refrigerant are discharged. The intermediate pressure refrigerant sucked by the evaporator in the refrigerator compartment of the refrigerator is sucked into the second compression unit 4 via the intermediate pressure suction pipe 2c, compressed to a high pressure, and then discharged to the outside of the machine through the discharge pipe 2b. The first compression unit 3 and the second compression unit 4 are integrally formed in a frame 6 attached to the upper side of the motor unit 5. The first compression unit 3 has a cylinder block 31 provided with a cylinder 31c having a suction port 31a and a discharge port 31b, and a reciprocating movement of the compression chamber 31d in the cylinder 31c to the cylinder 31c. The inner piston 32; and the connecting rod 33 of the piston 32 and the crank shaft 51 are coupled by a ball joint. A ball joint portion 33a of a ball joint is formed at one end of the link 33, and the ball portion is movably fitted to the ball seat 32c provided on the back surface 32b of the piston 32, and a cylindrical joint portion 33b is formed at the other end. The crank portion 5 la of the crank shaft 51 is rotatably fitted. Further, as shown in Fig. 3, a buffer ring 34 is provided between the ball seat 32c (6) 1247851 of the piston 32 and the ball portion 3 3 a of the link 3 3 . The buffer ring 34 is composed of PTFE having a perfluoroalkoxy group or crosslinked PTFE. Although the perfluoroalkoxy-containing PTFE has a larger friction coefficient than PTFE, it has high resistance to latent denaturation and abrasion. Therefore, the buffer ring made of PTFE having a perfluoroalkoxy group is such that the cushion ring is less worn or settled even under an excessive load state at the time of heavy load operation or operation start. The compressor is excellent in durability and high in durability. Reliability and high performance. Further, the specific wear of the crosslinked PTFE is about 1/104 (mm 3 / N - m ) of PTFE, and the occurrence of creep is reduced to about 1/2. Therefore, the compressor using the buffer ring made of crosslinked PTFE can perform stable operation even with high load accompanying vibration, improve reliability, and the friction coefficient is larger than PTFE but is extremely small, so it does not It increases the frictional resistance and maintains the high efficiency of the compressor. Further, the perfluoroalkoxy group-containing PTFE or the crosslinked PTFE used in the buffer ring 34 preferably contains 10% by weight or less of glass fiber or carbon fiber, more preferably 5% by weight. A high degree of reliability can be obtained by making 1% by weight or less. A single wear slip test of PTFE with perfluoroalkoxy group added to glass fiber or carbon fiber proves that it can suppress the wear amount of about 1/2 of PTFE, even in heavy load when assembled in a compressor The buffer ring wears less or settles under excessive load conditions at the start of operation or operation. Since the enthalpy charge is made 10% by weight or less, it is not necessary to extremely increase the elastic modulus of the material. Therefore, there is no need for a strong caulk ball seat, with -10-(7) 1247851 and the conventional The insertion operation of PTFE at the same time enables the buffer ring to adapt to the ball portion, and can achieve a predetermined performance with a short insertion operation, achieving energy-saving. Further, when the amount of the glass fiber or the carbon fiber is more than 10% by weight, the amount of wear of the buffer ring is increased. Further, since the elasticity is also high, it is necessary to strongly smash the ball seat, and it takes a longer time to adapt the buffer ring to the ball portion than the conventional PTFE. Further, PTFE or crosslinked PTFE having a perfluoroalkoxy group containing 10% by weight or less of glass fibers or carbon fibers is excellent in abrasion resistance, so that high reliability can be ensured even with a slight lubricating oil. It also reduces the sliding loss with the ball and improves the operating efficiency. Further, by setting the compression modulus of the buffer ring to 100 MPa or less, the ball seat can be folded with a small force, and the buffer ring can be adhered to the spherical surface. Therefore, the sliding loss between the buffer ring and the ball portion can be reduced. When the compression modulus of the buffer ring exceeds 1000 MPa, it is necessary to use a large gap force in order to make the buffer ring adhere to the ball portion, so that the above-described sliding loss is increased, so that the operation efficiency is lowered. Further, when the ball seat is folded, the adhesion between the buffer ring and the ball portion is inferior, and a gap is formed between the buffer ring and the ball portion to form a local contact, so the sliding loss between these increases. Further, the presence of the gap 'has a so-called wander between the ball portion and the buffer ring, so that the piston movement becomes unstable. In extreme cases, there will also be a ball that is detached from the tee and becomes uncompressible. Therefore, by setting the compression modulus of the buffer ring to 1000 MPa or less, the buffer ring can be adhered to the spherical surface with a small gap force, so that local wear can be prevented, and the reliability of the height can be ensured. Further, the second compression portion 4 has the same structure as that of the first compression portion 3, and -11-(8) 1247851 is disposed in the first compression portion 3 and the crankshaft 51 in an axisymmetric manner. The second compression unit 4 includes a cylinder 41 having a cylinder 41c having a suction port 41a and a discharge port 41b, a piston 42 that reciprocates in a compression chamber 41d in the cylinder 41c, and a piston 42 and a crank. The connecting rod 43 of the shaft 51. A ball portion 43a is formed at one end of the link 43, and the ball portion is movably fitted to the ball seat 42c provided in the piston 42, and at the other end, a cylindrical joint portion 43b is formed, and the joint portion is rotatably The joint portion 33b' of the link 33 fitted to the first compression portion 3 has a gap portion through which the link 33 can be rocked. Further, a buffer ring 44 is provided between the ball seat 42c of the piston 42 and the ball portion 43a of the link 43, and the buffer ring 44 is made of PTFE having a perfluoroalkoxy group or crosslinked PTFE. In the figure, the reference numeral 2c is an intermediate pressure refrigerant suction pipe. Next, a description will be given of a method of compressing a refrigerant using the hermetic two-stage compression type compressor of the present invention. In the configuration shown in FIGS. 1 and 2, when the crankshaft 51 rotates in the counterclockwise direction, the refrigerant gas is sucked into the compression chamber 31d in the suction stroke in which the piston 32 moves from the top dead center toward the bottom dead center. . At this time, the refrigerant gas is sucked into the compression chamber 3 Id through the suction port 2a of the first compression unit 3 via the suction pipe 2a. At the compression stroke in which the piston 32 is moved from the bottom dead center toward the top dead center, the refrigerant gas is compressed into the intermediate pressure PM and then ejected into the sealed casing 2. As shown in Fig. 5, in the suction stroke of the first compression unit 3, the pressure of the refrigerant gas sucked into the compression chamber 3 1 d is formed only by the refrigeration cycle due to the passage impedance from the refrigeration cycle to the compression chamber 31 d. The internal refrigerant gas pressure PL lowers the pressure (PL-dP) of the pressure dP of the passage impedance portion. -12· 1247851 Ο) In the case where the refrigerant is returned from the refrigeration cycle in a liquid state, the pressure dP of the impedance portion of the passage becomes extremely large. The pressure (PL-dP) is applied to the front surface 32a of the piston 32 in the suction stroke of the first compression unit 3, and the intermediate pressure PM of the refrigerant in the sealed casing 2 is applied to the back of the piston 32 facing the inside of the sealed casing 2. 32b, so the differential pressure (load) acting on the piston 32 is formed (PM + dP-PL). By this differential pressure (PM + dP-PL ), the piston 32 is subjected to the pulling force toward the top dead center. Because of the pulling force, in addition to (PM + dP-PL), the sliding loss between the piston 32 and the pressure cylinder 3 1c acts more on the inertial force of the piston 32 (in the experiment, the force exceeds 10 kgf), so that the piston When the power is received in the top dead center direction (the right direction in FIG. 2) and the crank shaft 51 is rotated in the counterclockwise direction, the crank shaft 51 is moved in the left direction in the second drawing, so that the ball portion 33a and the buffer ring 34 are pressed. . Further, since the crankshaft 51 performs the eccentric motion, the ball portion 33a performs the rotational motion in accordance with the eccentric motion. Since the differential pressure (PM + dP-PL ) becomes large at the time of excessive operation such as the start of operation of the compressor, the load applied to the buffer ring 34 becomes large. Further, since a differential pressure (PM + dP-PL ), a sliding resistance, and an inertial force are applied, a large load is applied to the buffer ring 34. Therefore, the buffer ring 34 is subjected to a load in a state where it is slid with the ball portion 33a that performs the rotational movement, and therefore it is necessary to be able to bear the load. Further, since the buffer ring 34 is formed at a high temperature in the compression chamber 31 d when the refrigerant is compressed, the piston 32 is also formed at a high temperature, so that it is required to have excellent heat resistance. Further, since the buffer ring 34 is coupled to the ball seat 32c of the nip piston 32, it is required to have a predetermined elasticity. Therefore, the buffer ring is required to have a perfluoroalkoxy-containing PTFE or crosslinked PTFE which satisfies the above heat resistance and elasticity - 13 - (10) 1247851. By using either of them, the wear or settling of the buffer ring can be reduced. As a result, the compressor improves durability and increases reliability and performance. As shown in Fig. 6, the second compression unit 4 sucks the refrigerant gas having the intermediate pressure PM in the sealed casing 2 during the suction stroke. Therefore, the suction pressure of the compression chamber 41d is reduced only by the passage impedance pressure dP. (PM-dP), pressure (PM-dP) is applied to the front face 42a of the piston 42, and the intermediate pressure PM is applied to the back face 42b of the piston 42, and the force (load) acting on the piston 42 is only the pressure caused by the suction resistance. dP, there is no large load applied to it. Therefore, the buffer ring 44 of the second compressing portion 4 is not necessarily required to be composed of PTFE or crosslinked PTFE having a perfluoroalkoxy group, and can be composed of PTFE which is a single polymer similarly to the conventional buffer ring. In addition, although the inertial force of the piston is increased in the suction stroke of the second compression unit 4, since the inertial force is affected by the mass, the speed, and the like of the piston, the second compression unit 4 is changed in compression load. In the case of a large one, it is necessary to maintain the strength so that deformation due to compression or the like does not occur, and in this case, the thickness of the piston is increased to a thickness or the like. Since the inertial force is proportional to the mass, the load applied to the buffer ring increases. Therefore, in this case, the buffer ring of the second compression portion is preferably formed of PTFE having a perfluoroalkoxy group or crosslinked PTFE in the same manner as the buffer ring of the first compression portion. However, it is not necessary to have the same characteristics of the buffer ring of the second compression unit and the first compression unit. In the case where the two have different characteristics, if -14-(11) 1247851 can be distinguished by color in advance, it is very convenient to prevent mistakes during assembly. Further, in accordance with the compression of the first compression portion and the compression ratio of the second compression portion, the specifications of the cylinder bore of the first compression portion and the pressure cylinder of the first compression portion can be appropriately set. According to the above-described sealed two-stage compression type compressor of the present embodiment, the intermediate pressure in the sealed casing or the high-pressure refrigerant gas causes a large load to be applied to the piston of the first compression portion, and also applies Sliding resistance and inertial force. However, since the buffer ring is made of PTFE or crosslinked PTFE having a perfluoroalkoxy group, abrasion or sedimentation of the buffer ring can be reduced even during heavy-duty operation or high-temperature operation. As a result, the compressor improves durability and increases reliability and performance. In addition, since the buffer ring contains 10% by weight or less of glass fiber or carbon fiber, it can be adhered to the ball portion with a small force when the ball seat is closed, even when it is just after assembly is completed, The surface of the buffer ring supports the load, and the surface pressure can be reduced. Since the compression modulus of the buffer ring is 1000 MPa or less, it can be adhered to the ball portion with a small gap force, so that local wear can be prevented. Maintain high reliability. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional view showing an embodiment of a hermetic two-stage compression type compressor of the present invention. Fig. 2 is a cross-sectional view showing an embodiment of a hermetic two-stage compression type compressor of the present invention. Fig. 3 is a longitudinal sectional view showing a piston portion of a configuration of a hermetic two-stage compression type compressor of the present invention in the form of -15· 1247851 (12). Fig. 4 is a cross-sectional view taken along line A-A of Fig. 3. Fig. 5 is a longitudinal sectional view showing the suction of the first compression portion of the embodiment of the hermetic two-stage compression type compressor of the present invention. Figure 6 is a longitudinal cross-sectional view showing the suction of the second compression portion of the embodiment of the hermetic two-stage compression type compressor of the present invention. Fig. 7 is a longitudinal sectional view showing the suction of the first compression portion of the embodiment of the conventional hermetic two-stage compression type compressor. Fig. 8 is a vertical cross-sectional view showing the suction of the second compression portion of the embodiment of the conventional hermetic two-stage compression type compressor. [Description of main components] 1: Closed-type two-stage compression compressor 2...Closed box 3...First compression unit 4...Second compression unit 5...Motor unit 32...Piston 32c...Seat 33...Connector
3 3 a · · ·球咅B 34···緩衝環 42…活塞 42c···球座 -16- (13)1247851 43…連桿 43a…球部 44…緩衝環3 3 a · · · Ball 咅 B 34···Buffer ring 42...Piston 42c···Seat -16- (13)1247851 43...link 43a...ball 44...buffer ring
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