根據以下圖式說明本發明之實施型態。 圖1係第一實施型態的冰箱之正面圖。在本例，冰箱本體1，為由上起依序被構成冷藏室2、製冰室3、第一冷凍室4、第二冷凍室5、蔬菜室6而配置之構造。又，冷藏室2及蔬菜室6，係其內部溫度在冷藏溫度帶之貯藏室，另一方面，製冰室3及第一冷凍室4、第二冷凍室5，為其內部溫度在0℃以下的冷凍溫度帶(例如約-20℃～-18℃的溫度帶)之貯藏室。此外，圖中的符號11為操作面板，設置於冷藏室門2a。 於冰箱本體1的前面，設有前述之複數的門，這些門之中，冷藏室2a、2b，為閉塞冷藏室2的前面開口部之門，製冰室門3a，係供閉塞製冰室3的前面開口部之用的門，第一冷凍室門4a，為供閉塞第一冷凍室4的前面開口部之用的門，第二冷凍室門5a，為供閉塞第二冷凍室5的前面開口部之門，接著，蔬菜室門6a，為供閉塞蔬菜室6的前面開口部之用的門。又，冷藏室門2a、2b，以所謂的左右對開式之雙開式門來構成，於該冷藏室1，於稍後會詳述，附圖2為拆下所有的門之冰箱的正面圖，具備供檢測冷藏室門2a、2b的開閉之用的冷藏室門開關7。另一方面，製冰室門3a、第一冷凍室門4a、第二冷凍室門5a、蔬菜室門6a藉由拉出式的門來構成，與拉出門一起，成為貯藏室內的容器被拉出之構造。此外，具備著：供檢測第一冷凍室門4a的開閉之用的第一冷凍室門開關8、於圖２供檢測製冰室門3a與第二冷凍室門5a之分別的開閉之用的製冰室門/第二冷凍室門開關9(於開關基板分別被搭載檢測製冰室門3a的開閉之用的元件、檢測第二冷凍室門5a的開閉之用的元件，但基板為1個所以匯集表示)、以及供檢測蔬菜室門6a的開閉之用的蔬菜室門開關10。此外，如圖2所示，於冰箱1的冷藏室內具備檢測冷藏室內的溫度之冷藏室溫度感測器17。 接著，於附圖1的冷藏室2內的最下段具備減壓貯藏室12。圖3為減壓貯藏室12之立體圖，減壓貯藏室12中介著導管13被連接於減壓手段亦即真空泵14，從而，成為減壓該內部空間的構造。又，於此減壓貯藏室12的前面，被形成食品出入用之開口部，而且具備供密閉開閉該開口部之減壓貯藏室門12a。 於前述構成，使用以下圖4～圖13說明將減壓貯藏室12內進行減壓動作之實施型態。 ＜控制方塊＞ 圖4係控制方塊圖。於圖4，符號15顯示設於冰箱的一部分之微電腦(micro computer)。此外，如同前述圖2也顯示的，對應於前述冷藏室2的前述雙開式的門2a,2b雙方，設有供感知其開閉之一對冷藏室門開關7，來自這些冷藏室門開關7(在圖4將這些匯集顯示為1個冷藏室門開關7)的檢測訊號被輸入前述微電腦15。(又，冷藏室門為單片的場合，設有檢測單片冷藏室門開閉之冷藏室門開關7)此外，來自供檢測製冰室門3a與第二冷凍室門5a之分別的開閉之製冰室門/第二冷凍室門開關9、供檢測第一冷凍室門4a的開閉之第一冷凍室門開關8、供檢測蔬菜室門6a的開閉之蔬菜室門開關10、以及冷藏室溫度感測器17之檢測訊號被輸入微電腦15。 亦即，微電腦15，根據來自前述冷藏室門開關7、第一冷凍室門開關8、製冰室門/第二冷凍室門開關9、蔬菜室門開關10的檢測訊號，依照後述之控制規格，對前述真空泵14輸出控制訊號。又，真空泵14，如圖所示，具備作為其驅動力源之直流馬達，前述微電腦15，藉由控制該直流馬達的旋轉動作，控制真空泵14的動作。 其次，於圖5顯示運轉真空泵14時之減壓性能之一例。橫軸為在大氣壓狀態使真空泵7開始運轉起算的運轉時間，縱軸顯示減壓貯藏室12內的壓力。又，在本說明書中，壓力值為表壓，其單位以kPa･G表示。亦即，大氣壓=0kPa･G，比其更為低壓時為負值。 亦即，由圖5之圖式可知，關閉減壓貯藏室門12a後，連續運轉真空泵14開始減壓貯藏室12的減壓時，伴隨著時間經過壓力也徐徐降低，但由於減壓貯藏室12的容積變動(亦即，內部未收容食品的場合或收容了的場合)，使得真空開始初期之壓力狀態的變動速度(斜率)會改變。總之，對於抽吸的空氣量不同，使用相同的真空泵14的場合，容積越小壓力下降的速度應該會幾乎比例於減壓貯藏室12的容積地變快。 在此考慮在減壓貯藏室12之減壓動作。減壓貯藏室12自身的容積在做出決定的使用者把食品收容於減壓貯藏室12的場合，減壓貯藏室12內的可抽吸之空氣量會減少，所以與減壓貯藏室12的實質容積變小是相同的。減壓貯藏室12的減壓目標壓力例如為-20kPa･G的場合，單純使真空泵14的運轉時間配合減壓貯藏室的容積而設定，進行控制的話可以是簡單的控制。 在此不使用壓力開關18進行減壓控制。如圖6那樣使用壓力開關18的話，有必要再真空泵內形成壓力開關用的密閉室。如此，設置複數密閉空間的話，該部分使空氣洩漏的可能性也跟著增加。如圖7那樣不利用壓力開關18的場合，密閉空間減少，可以減少空氣洩漏的可能性。 在本實施型態，冷藏室門2a,2b之從開門到閉門為止的時間為特定時間A以上的場合，視為有利用減壓貯藏室12，而使真空泵14動作。如此，根據門的開閉時間來切換真空泵的開/關(運轉/停止)的話，不設壓力開關也可以控制真空泵，使得洩漏控制與低成本化成為可能。又，門的開閉時間，藉由冷藏室門開關7來測定。 前述的特定時間A，具體以設定為3秒為較佳。其次，說明供使真空泵動作的條件亦即開門時間3秒的根據。 於冰箱1，開閉減壓貯藏室12而取出放入食品時，必須經歷打開冷藏室門2a,2b，打開減壓貯藏室12的門12a，拉出減壓貯藏室12的托盤，拿出放入食品，返回托盤而關閉減壓貯藏室的門12a，關閉冷藏室門2a,2b等一連串的程序，與不利用減壓貯藏室12的場合相比時間變長。 在此，具體需要多長的時間，使用如冰箱1那樣冷藏室門為雙開門之冰箱，根據21人的實驗來確認。進行結果，平均時間為約7秒，考慮到離散差異的結果，使冷藏室門2a,2b之雙開時間經過3秒時始真空泵動作的話，可以在利用減壓貯藏室12以外的冷藏室的場合，防止浪費地啟動真空泵的情形。又，如本實施型態這樣採用左右對開方式的場合，門的開閉時間A，係指從最初打開左右任一門起，直到關閉左右單方之門為止的時間。 圖8、9、10為進行減壓動作時之基本控制流程圖。本流程圖，在從打開冷藏室門2a,2b到閉門為止的時間為特定時間以上的場合，視為有利用減壓貯藏室12，使真空泵動作。又，控制開始時(步驟S1)，係以減壓貯藏室12內的壓力在0kPa･G附近為前提而設想電源打開時。 電源打開之後，真空泵12未進行動作所以在步驟S2為運轉停止。接著，在步驟S3判定冷藏室門2a,2b的開閉狀態。步驟S3，有步驟S5(參照圖9)的條件，隨著冷藏室門為左右對開的兩扇門(雙開門)還是單片門(單一門)之不同動作會不同。又，冰箱1為冷藏室門有兩扇的左右對開之冰箱。(冰箱1為搭載著冷藏室門2a,2b之左右對開之門的冰箱，在下列流程圖，也對應於單片門的冰箱的控制。) 以下說明雙開門的冰箱的流程圖。 在步驟S6～S9(參照圖9)，冷藏室門2a,2b為雙開的場合，測定冷藏室門2a,2b雙開的時間(計數i)。其後，在步驟S15判定計數i時間，未滿A秒的場合在步驟S16重設計數i，真空泵不運轉。步驟S15的計數i時間為A秒以上的場合，認為有減壓貯藏室12之門12a的開閉，進至步驟S17，重設計數i時間。又，作為計數冷藏室門2a,2b雙開的時間的理由，是因為考慮在冰箱1，開閉減壓貯藏室12而取出放入食品時，必須經歷打開冷藏室門2a,2b，打開減壓貯藏室12的門12a，拉出減壓貯藏室的托盤，拿出放入食品，返回托盤而關閉減壓貯藏室的門12a，關閉冷藏室門2a,2b等一連串的程序，與不利用減壓貯藏室12的場合相比時間變長。又，本實施型態之減壓貯藏室12，被設置於跨冷藏室門2a,2b雙方的區域，所以進行減壓貯藏室的門12a的開閉，冷藏室門2a,2b之任一方都有打開的必要。假設是小型的減壓貯藏室而收容於一方之冷藏室門的背面側區域內的場合，只要考慮該一方的冷藏室門即可。 在步驟S18～S23，冷藏室門2a,2b成為雙閉起，開始計數ii(真空泵14運作等待時間計數)的測定。設「計數ii」(真空泵14運作等待時間計數)的理由，是在進行料理中冷藏室門2a,2b在短時間內頻繁開閉的場合，防止真空泵14的動作次數增加的緣故。計數ii的途中遇到打開冷藏室門2a,2b的場合，重設計數ii，重新開始計數ii。 在步驟S24確認冰箱1的冷藏室門2a,2b、製冰室門3a、第二冷凍室門5a、第一冷凍室門4a、蔬菜室門6a全部為關閉的狀態，步驟S25開始真空泵14的運作，從步驟S26開始進行技數iii(真空泵14運作時間計數)之量測。 在步驟S26～44，是真空泵14動作時之控制。在步驟S27，在冷藏室內溫度成為45℃以上時(冷藏室溫度感測器17感知45℃以上的溫度時)，為了防止超過真空泵14的使用溫度範圍，停止真空泵的運作。 在步驟S28～S34，於計數iii中監視冰箱1的冷藏室門2a,2b、製冰室門3a、第二冷凍室門5a、第一冷凍室門4a、蔬菜室門6a的門的開閉，有哪個門打開的場合，停止真空泵14的運作，停止計數iii。在步驟S33(參照圖10)，監視冷藏室門2a,2b(與圖9之步驟S4～S14同樣)。 雙開門的場合，在步驟S6～S9測定冷藏室門2a,2b雙開的時間(計數i)。其後，在步驟S35判定計數i時間，計數i時間為A秒以上的場合，視為有減壓貯藏室12的門12a的開閉，在步驟S36,37重設計數iii與i，移往步驟S18的計數iii(真空泵14運作等待時間計數)開始。 在步驟S35計數i未滿A秒的場合，在步驟S38重設計數i，在步驟S39判斷計數iii是否停止(打開冰箱1的冷藏室門2a,2b、製冰室門3a、第二冷凍室門5a、第一冷凍室門4a、蔬菜室門6a之任一扇門的場合，在步驟S31會使真空泵14停止運作的緣故)，停止的場合，在步驟S40、S41使真空泵14的運作與計數iii再次開始。亦即，雙開冷藏室門2a,2b的場合下，只要冷藏室門2a,2b的雙開時間未達A秒的場合，在冷藏室門2a,2b之某一方打開的時間點停止真空泵14與計數iii，等冷藏室門2a,2b成為雙閉開始再次開始真空泵14的運作與計數iii。 真空泵14運作C秒後，在步驟S43、44進行計數iii的結束與重設，在步驟S16重設計數i，在步驟S2停止真空泵的運作。 如前所述，減壓貯藏室12內的壓力達到減壓目標壓力後，只要利用者不打開減壓貯藏室門12a，減壓貯藏室12內的壓力基本上保持低壓狀態。然而，要達到使包含真空泵14、導管13、減壓貯藏室12的空間完全密閉的構造是很難的，會產生微小的空氣洩漏(漏氣)。在此，如同前述圖5也揭示的，只要空氣由減壓貯藏室12的外部往內部洩漏，其內部壓力會徐徐上升，最後回到0kPa･G(大氣壓)(參照圖11的虛線)。 圖11係於前述流程圖開始真空泵14的運作(真空泵狀態「ON：運作」)，其後僅C秒(C時間)繼續運作。亦即，在此圖11，於其縱軸表示減壓貯藏室12內的壓力狀態，而且進而於其下方，顯示真空泵14的開/閉(ON/OFF)狀態。 據此，如前所述，減壓貯藏室12的壓力，即使其容積有變動，也大致徐徐地減壓到特定的壓力(=減壓目標壓力)。其後，在停止運作僅特定的時間(D時間)後，推測減壓貯藏室12內的壓力會再度回到有減壓必要的壓力(目標上限壓力)(空氣洩漏著)，在此，再度開始真空泵14的運作。又，由此目標上限壓力進行減壓到減壓目標壓力所必要的真空泵14的運作時間(E時間)，也與前述同樣，可以預先設定。接著，根據反覆進行此運作，不用檢測減壓貯藏室12內的壓力，就可以使減壓貯藏室12內的壓力維持於所要的低壓。亦即，藉著以減壓貯藏室12的內容積與減壓貯藏室12的減壓目標壓力為根據來設定真空泵14的運作時間，藉由僅僅控制真空泵的運作時間之比較簡單的控制方式，就可以不利用壓力開關而且以低成本來實現可信賴性高的具備低壓室的冰箱。 圖12係針對圖8,9,10之流程圖的冷藏室門2a,2b之雙開判定與圖11之D時間與E時間來補足說明之時序圖。冷藏室門(在圖12表示為冷藏室門，但雙開門為冷藏室門2a,2b雙方，單片門為冷藏室門1片)之開的時間為T0＜A(計數i的判定時間)的話，真空泵14不運作。冷藏室門(在圖12表示為冷藏室門，但雙開門為冷藏室門2a,2b雙方，單片門為冷藏室門1片)之開的時間為T0≧A(計數i的判定時間)的話，視為減壓貯藏室12的減壓貯藏室門12a被開閉，在真空泵14之運作等待時間B秒後真空泵14開始運作。又，如圖12所示的，冷藏室門2a,2b之雙開的時間為T0≧A(計數i的判定時間)的話，不管減壓貯藏室12的減壓貯藏室門12a是否開閉真空泵14都運作。此外，真空泵14運作後在D時間內繼續，而冷藏室門2a,2b之雙開的時間未達到T0≧A(計數i的判定時間)的場合，考慮如前所述之空氣的洩漏，使真空泵14運作E時間。 又，於本控制，在前述之D時間內繼續運作而冷藏室門2a,2b之雙開的時間未達T0≧A(計數i的判定時間)的場合，因為已經某個程度被減壓了，到達減壓目標壓力之到達時間很短就夠了。在此，真空泵16的運作時間為C時間＞E時間，藉著不使真空泵14進行不必要的運作以謀求高壽命化。 圖13係在圖8,9,10之流程圖的真空泵14運作時冷藏室門2a,2b之開判定(在圖13表示為冷藏室門，但雙開門為冷藏室門2a,2b之某單一方，單片門為冷藏室門1片)的場合之補足說明的時序圖。冷藏室門2a,2b之雙開的時間為T0≧A(計數i的判定時間)的話，視為減壓貯藏室12的減壓貯藏室門12a被開閉，運作真空泵14如前所述。於真空泵14之運作中，使冰箱1的冷藏室門(雙開門的話為冷藏室門2a,2b之某單一方，單片門為冷藏室門1片)、製冰室門3a、第二冷凍室門5a、第一冷凍室門4a、蔬菜室門6a之中有哪個門打開的場合，停止真空泵14的運作。 冷藏室門(雙開門的話為冷藏室門2a,2b雙方，單片門為冷藏室門1片)之雙開時間為T2＜A(計數i的判定時間)的話，冰箱1之所有門關閉後再度開始真空泵14的運作。又，真空泵14的運作時間為C=C1+C2(合計動作C時間)。 冷藏室門(雙開門的話為冷藏室門2a,2b雙方，單片門為冷藏室門1片)之雙開的時間為T2≧A(計數i的判定時間)的話，視為減壓貯藏室12的減壓貯藏室門12a被開閉，不管真空泵14停止前之運作時間C3，在真空泵14之運作等待時間B秒後真空泵14運作C時間。 藉由以上的方法，可以發揮根據在本體內部具備其內部壓力被減壓的減壓貯藏室12的冰箱1的話，可以不利用壓力開關，藉由比較簡單的控制，以低成本來實現具備可信賴性高的減壓貯藏室12之冰箱1，進而也可以達成真空泵14的長壽命化，或者解消伴隨著壓力檢測手段的安裝之空氣洩漏等優異的效果。 其次，說明不使用壓力開關而抑制過剩的真空泵開啟同時使減壓貯藏室12內進行減壓動作之其他實施型態(第二實施型態)。 圖14係控制方塊圖。符號17為檢測冷藏室2內的溫度之溫度感測器，符號15為被搭載於冰箱控制基板(未圖示)的微電腦，符號20a為被組入操作面板20內的顯示LED，符號14b為驅動真空泵14的直流馬達。係冷藏室門開關7、減壓貯藏室門開關21、冷藏室溫度感測器17分別的檢測訊號被輸入微電腦15，根據後述的控制規格對顯示LED20a及真空泵14(直流馬達14b)輸出輸出訊號的構成。此外，電流訊號14c室表示直流馬達14b的馬達電流之訊號，訊號往微電腦15反饋。此外，被反饋至微電腦15的電流訊號14c，藉由被實裝於冰箱控制基板上的電流放電電路22放大，成為可以更精度佳地檢測出微小的電流增減的構成。 其次，圖15，顯示使真空泵14繼續運作時之減壓貯藏室12的內部的壓力狀態，與電流訊號14c的狀態。橫軸為使真空泵14開始運轉起算的運轉時間，縱軸顯示減壓貯藏室12內的壓力、電流訊號14c的高低。又，在本說明書中，壓力值為表壓，其單位以kPa･G表示。亦即，大氣壓=0kPa･G，比其更為低壓時為負值。 把真空泵14連接於減壓貯藏室12而運作時，根據發明人等的實驗，如圖15那樣使真空泵14開始運作時，隨著時間經過壓力也徐徐降低。此處，使用本實施型態之真空泵14的減壓能力不為-30kPa･G以下的泵。藉著使用這樣的泵，對於減壓貯藏室12的容積不同的，也就是抽吸的空氣量不同時，真空泵14都使用相同泵的場合，容積越小壓力下降的速度應該會變快，但是在本實施型態，減壓貯藏室12內部的壓力應該不會低於-30kPa･G。 另一方面，電流訊號14c，隨著低壓室內壓力的降低而增大電流值。此現象是由於作為真空泵14的動力源使用的直流馬達14b的特徵所致。直流馬達具有馬達負荷與馬達電流成比例的特徵，所以隨著低壓室內的氣壓降低馬達負荷增大，電流值也增大。 成為一定壓力以下的場合，泵機構的作功量減少(變得不能減壓)所以馬達負荷減低導致馬達電流降低。 於前述之冰箱，使用圖16所示之時序圖與圖17所示之流程圖來說明以不具有檢測壓力的開關之真空泵，來檢測出減壓貯藏室12內的壓力為特定壓力以下之控制規格。 首先，減壓貯藏室12被收容於冷藏室2的內部，藉由冷藏室門2a有無開閉來判斷是否打開真空泵7。 於本實施型態，只有在冰箱門2a打開(S001)之後直到關閉(S002)為止的時間為3s以上時才打開真空泵。(S003)。開閉時間未滿3s的場合使真空泵維持關閉(OFF)(S004)，3s以上的場合打開(ON)真空泵7(S005)。 在此，說明供使真空泵動作的條件亦即開門時間3秒的根據。開閉減壓貯藏室12的減壓貯藏室門12a而取出放入食品時，必須經歷打開冷藏室門2a(左右對開方式的雙開門的場合為左右兩側之門)，打開減壓貯藏室門12a，拉出托盤，拿出放入食品，返回托盤而關閉減壓貯藏室門12a，關閉冷藏室門2a等一連串的程序，與不利用減壓貯藏室12的場合相比時間變長。 在此，具體需要多長的時間，使用冷藏室門為雙開門之冰箱，根據21人的實驗來確認。進行結果，平均時間為約7秒，考慮到離散差異的結果，使冷藏室門之雙開時間經過3秒時始真空泵動作的話，可以在利用減壓貯藏室12以外的冷藏室的場合，防止浪費地啟動真空泵的情形。 於真空泵開啟中檢測冷藏室門有無開閉(S006)，有開閉的場合，結束低壓檢測控制，在冰箱門關閉後直到第3特定時間(t3)為止打開真空泵，結束動作(S007)。 此處，第3特定時間(t3)，設定為使減壓貯藏室12內部的壓力在-15～-20kPa･G之間之時間，於本實施型態設定為150s等之值。第3特定時間(t3)隨著減壓貯藏室12的容積而改變，有必要例如20L設為150s，10L設為75s那樣隨著容積而改變設定時間。 在沒有冷藏室門的開閉的狀態下經過第1特定時間(t1)的場合，測定當時的第1電流值(I1)(S008)。如圖16之時序圖所示，直流馬達14b在開啟之後會有比通常電流還要大非常多的電流(突波電流)流動，為了不要錯誤檢測出而在真空泵14開啟後經過第1特定時間(t1)之後才測定第1電流值(I1)。突波電流大概在數ms～數百ms，於本實施型態把第1特定時間設為10s。 其後，直到第2特定時間(t2)為止的期間沒有冷藏室門2a的開閉的場合，測定第2電流值(I2)(S011)。第2特定時間(t2)經過前有冷藏室門的開閉的場合結束低壓檢測控制，在冰箱門關閉後直到第3特定時間(t3)為止打開真空泵，結束動作。(S010) 在此，第2特定時間(t2)設定為比第3特定時間(t3)還短的時間，藉此，減壓貯藏室12內已經為低壓而沒有更進一步減壓的必要的場合，可以抑制過剩的真空泵14的動作。 如前所述，直流馬達14b會隨著馬達負荷而增減電流值，所以為了充分確保壓力的變化幅度，第2特定時間以儘量長為較佳。但是，為了抑制過剩的真空泵14的啟動，有必要採用儘可能短的時間。於本實施型態，第2特定時間(t2)設定為第3特定時間(t3)的30～70%。例如把第3特定時間(t3)設定為150s的低壓室容量的場合，把第3特定時間設定為75s。 演算第1電流值(I1)與第2電流值(I2)之差分(S012)，比較其結果(⊿I)與0kPa･G(大氣壓)與供判定低壓之閾值(X)(S013)。⊿I＜X的場合，把減壓貯藏室12內的壓力判斷為低壓而關閉真空泵14。(S014)。⊿I≧X的場合，把減壓貯藏室12內的壓力判斷為0kPa･G(大氣壓)而使真空泵14繼續開啟直到第3特定時間(t3)為止。(S015) 藉由以上的控制規格，使減壓貯藏室12內的壓力由直流馬達14b的電流來推定，可以抑制浪費的真空泵14的動作。藉此，藉由不使用壓力開關而判別減壓貯藏室12內的壓力，可以提供減低洩漏的可信賴性高的冰箱。又，在此所謂的洩漏，是指在減壓貯藏室或真空泵之密閉空間，藉由被減壓的密閉空間與密閉空間外的壓力差，使空氣從密閉空間的間隙留置密閉空間。 其次，進而藉由其他的實施型態(第三實施型態)，說明以更單純的控制，不使用壓力開關而抑制過剩的真空泵開啟同時使減壓貯藏室12內進行減壓動作之實施型態。又，零件構成與第二實施型態相同。 本實施型態之時序圖顯示於圖18，流程圖顯示於圖19。 首先，針對S016至S022為止的動作，進行與在第二實施型態說明的S01到S07相同的動作。 啟動真空泵14後(S020)，繼續運轉到第4特定時間為止的場合，測定當時之第4電流值(I4)(S023)。 比較第1電流值(I1)與低壓判定值Y(S024)，I1＜Y的話判斷為低壓，關閉真空泵14(S025)，I1≧Y的話判斷為0kPa･G(大氣壓)，使真空泵14繼續運作到第3特定時間(t3)為止(S026)。 在此，於本實施型態之冰箱，第4特定時間設定為第3特定時間的50%以下的範圍的時間。如前所述，作為真空泵14的動力源使用的直流馬達14b，馬達電流是比利於馬達負荷的增加而增加。把第4特定時間設定為比第3特定時間的50%更長的場合，由0kPa･G(大氣壓)開始減壓也會使電流增加，與從低壓開始減壓的場合沒有明確的差異，判斷變得困難。此狀態時之電流訊號的變遷顯示於圖20。如圖20所示，由0kPa･G(大氣壓)啟動真空泵的場合，由低壓啟動真空泵的場合，第4電流值(I4)都比Y還大，成為無法判別的狀態。 另一方面，把第4特定時間設為第3特定時間的50%以下的場合，由0kPa･G(大氣壓)啟動真空泵的場合之第4電流值(I4)低於低壓判定值Y，0kPa･G(大氣壓)與低壓之判斷為可能。此狀態時之電流訊號的變遷顯示於圖21。 藉由以上的控制，可以提供以更單純的控制構成且不使用壓力開關而判別減壓貯藏室12內的壓力之冰箱。 (第四實施型態) 其次，敘述藉由直流馬達14b的轉速來判斷減壓貯藏室12內的壓力為0kPa･G(大氣壓)還是低壓的方法。 首先，於圖22顯示一般的直流馬達的特性圖。縱軸顯示電流[I]與轉速[min＾-1]，橫軸顯示扭矩[mNm]，扭矩表示施加於馬達的負荷的輕重。 根據圖22所示的特性圖，電流[I]隨著扭矩的增加而比例增加，轉速[min＾-1]具有成比例的特性。 於第二及第三實施型態，針對使用此電流[I]的低壓檢測方法加以說明，於本實施型態說明以轉速[min＾-1]來檢測低壓的方法。 使用轉速[min＾-1]之低壓檢測控制之時序圖顯示於圖23，流程圖顯示於圖24。以下，使用圖23與圖24說明動作。 控制流程與第二實施型態所示的S001～S015相同，但把檢測對象由電流變更為轉速。 與第二實施型態同樣，測定第1轉速(N1)與第2轉速(N2)，演算其差分⊿N(S038)，⊿N＜Z的場合，把減壓貯藏室12內的壓力判斷為低壓而關閉真空泵14。(S014)⊿N≧Z的場合，把減壓貯藏室12內的壓力判斷為0kPa･G(大氣壓)而使真空泵14繼續開啟直到第3特定時間(t3)為止。(S041) 藉由以上的動作，使減壓貯藏室12內的壓力由直流馬達14b的轉速來推定，可以抑制浪費的真空泵14的動作。藉此，藉由不使用壓力開關而判別減壓貯藏室12內的壓力，可以提供減低洩漏的可信賴性高的冰箱。 又，做為檢測直流馬達14b的轉速的手段，在DC有刷馬達的場合，可以由馬達的電流的頻率來求出。 此外，DC無刷馬達的場合，有在內藏的驅動基板上輸出轉速訊號(FG訊號)者，可以藉此檢測轉速。 於任一種馬達，在由轉速進行低壓檢測的場合，都可以不需要電流放大電路22，所以可實現更為廉價的低壓檢測規格。The embodiment of the present invention will be described based on the following drawings. FIG. 1 is a front view of the refrigerator of the first embodiment. In this example, the refrigerator body 1 has a structure in which the refrigerator compartment 2, the ice making compartment 3, the first freezer compartment 4, the second freezer compartment 5, and the vegetable compartment 6 are arranged in this order from the top. In addition, the refrigerator compartment 2 and the vegetable compartment 6 are storage compartments whose internal temperature is in the refrigerating temperature zone, and on the other hand, the ice making compartment 3, the first freezing compartment 4, and the second freezing compartment 5 have their internal temperatures at 0°C Storage room of the following freezing temperature zone (for example, a temperature zone of about -20°C to -18°C). In addition, the symbol 11 in the figure is an operation panel, and is provided in the refrigerator compartment door 2a. At the front of the refrigerator body 1, a plurality of the aforementioned doors are provided. Among these doors, the refrigerator compartments 2a and 2b are doors for closing the front opening of the refrigerator compartment 2, and the ice-making compartment door 3a is for blocking the ice-making compartment. The door for the front opening of 3, the first freezer compartment door 4a is a door for closing the front opening of the first freezer compartment 4, the second freezer compartment door 5a is for closing the second freezer compartment 5 The front opening door, and then the vegetable compartment door 6a, is a door for closing the front opening of the vegetable compartment 6. In addition, the refrigerator compartment doors 2a and 2b are constituted by so-called left-and-right double-open doors. The refrigerator compartment 1 will be described in detail later. FIG. 2 is a front view of the refrigerator with all doors removed. The refrigerator compartment door switch 7 for detecting the opening and closing of the refrigerator compartment doors 2a and 2b is provided. On the other hand, the ice compartment door 3a, the first freezer compartment door 4a, the second freezer compartment door 5a, and the vegetable compartment door 6a are constituted by a pull-out door, and together with the pull-out door, the container that becomes the storage compartment is pulled Out of the structure. In addition, the first freezing compartment door switch 8 for detecting the opening and closing of the first freezing compartment door 4a is provided, and in FIG. 2 for detecting the opening and closing of the ice making compartment door 3a and the second freezing compartment door 5a respectively Ice making room door/second freezing room door switch 9 (the switch board is respectively equipped with elements for detecting the opening and closing of the ice making room door 3a and elements for detecting the opening and closing of the second freezing room door 5a, but the substrate is 1 Therefore, the vegetable compartment door switch 10 for detecting the opening and closing of the vegetable compartment door 6a. In addition, as shown in FIG. 2, a refrigerator compartment temperature sensor 17 that detects the temperature in the refrigerator compartment is provided in the refrigerator compartment of the refrigerator 1. Next, a reduced-pressure storage compartment 12 is provided at the lowermost part of the refrigerator compartment 2 in FIG. 1. FIG. 3 is a perspective view of the decompression storage chamber 12, and the decompression storage chamber 12 is connected to the vacuum pump 14 which is a decompression means via a conduit 13 to decompress the internal space. In addition, an opening for food entry and exit is formed in front of the reduced-pressure storage compartment 12, and a reduced-pressure storage compartment door 12a is provided for sealingly opening and closing the opening. With the foregoing configuration, an embodiment of decompressing the decompression storage chamber 12 will be described using FIGS. 4 to 13 below. <Control Block> Figure 4 is the control block diagram. In FIG. 4, symbol 15 shows a micro computer installed in a part of the refrigerator. In addition, as also shown in FIG. 2 above, a pair of refrigerator door switches 7 for sensing the opening and closing of each of the double-open doors 2a, 2b corresponding to the refrigerator compartment 2 are provided. From these refrigerator door switches 7 ( In FIG. 4, these detection signals are collectively shown as one refrigerator compartment door switch 7 ), and the detection signal is input to the microcomputer 15. (Furthermore, when the refrigerator compartment door is a single piece, a refrigerator compartment door switch 7 for detecting the opening and closing of the single-piece refrigerator compartment door is provided) In addition, the detection and opening of the ice compartment compartment door 3a and the second freezer compartment door 5a respectively Ice making compartment door/second freezing compartment door switch 9, first freezing compartment door switch 8 for detecting opening and closing of the first freezing compartment door 4a, vegetable compartment door switch 10 for detecting opening and closing of the vegetable compartment door 6a, and refrigerating compartment The detection signal of the temperature sensor 17 is input to the microcomputer 15. That is, the microcomputer 15 is based on the detection signals from the aforementioned refrigerator compartment door switch 7, the first freezer compartment door switch 8, the ice compartment door/second freezer compartment door switch 9, and the vegetable compartment door switch 10, in accordance with the control specifications described later , Output a control signal to the vacuum pump 14. In addition, as shown in the figure, the vacuum pump 14 includes a DC motor as its driving force source. The microcomputer 15 controls the operation of the vacuum pump 14 by controlling the rotation of the DC motor. Next, FIG. 5 shows an example of the decompression performance when the vacuum pump 14 is operated. The horizontal axis represents the operation time from when the vacuum pump 7 starts to operate in the atmospheric pressure state, and the vertical axis represents the pressure in the decompression storage chamber 12. In this specification, the pressure value is a gauge pressure, and its unit is expressed in kPa･G. That is, atmospheric pressure = 0kPa･G, which is a negative value when it is lower than it. That is, as can be seen from the diagram of FIG. 5, after closing the decompression storage compartment door 12a, when the vacuum pump 14 is continuously operated to start decompression of the decompression storage compartment 12, the pressure gradually decreases with the passage of time, but due to the decompression storage compartment The volume change of 12 (that is, when no food is contained or when it is contained) changes the rate of change (slope) of the pressure state at the initial stage of vacuum start. In short, when the same vacuum pump 14 is used for different amounts of air to be sucked, the smaller the volume is, the faster the pressure drops. The speed should be almost proportional to the volume of the decompression storage chamber 12. Here, the decompression operation in the decompression storage room 12 is considered. The volume of the decompression storage compartment 12 itself is such that when a user who decides to store food in the decompression storage compartment 12, the amount of air that can be sucked in the decompression storage compartment 12 is reduced, so it is different from the decompression storage compartment 12 The substantial volume of the same becomes smaller. When the decompression target pressure of the decompression storage compartment 12 is, for example, -20 kPa･G, the operation time of the vacuum pump 14 is simply set in accordance with the volume of the decompression storage compartment, and the control can be a simple control. Here, the pressure switch 18 is not used for decompression control. When the pressure switch 18 is used as shown in FIG. 6, it is necessary to form a closed chamber for the pressure switch in the vacuum pump. In this way, if a plurality of closed spaces are provided, the possibility of air leakage increases at this part. When the pressure switch 18 is not used as shown in FIG. 7, the enclosed space is reduced, and the possibility of air leakage can be reduced. In the present embodiment, when the time from the opening of the refrigerator compartment doors 2a, 2b to the closing of the door is more than a specific time A, it is considered that the vacuum pump 14 is operated by using the decompression storage compartment 12. In this way, if the vacuum pump is switched on/off (operation/stop) according to the opening and closing time of the door, the vacuum pump can be controlled without a pressure switch, making it possible to control leakage and reduce costs. In addition, the opening and closing time of the door is measured by the refrigerator compartment door switch 7. The aforementioned specific time A is preferably set to 3 seconds. Next, the basis for the condition for operating the vacuum pump, that is, the door opening time of 3 seconds will be described. In the refrigerator 1, when opening and closing the decompression storage room 12 to take out and put in the food, it is necessary to open the refrigerator compartment doors 2a, 2b, open the door 12a of the decompression storage room 12, pull out the tray of the decompression storage room 12, take out and put out A series of procedures, such as loading food, returning to the tray, closing the door 12a of the decompression storage compartment, and closing the doors 2a, 2b of the refrigerator compartment, etc., takes longer than when the decompression storage compartment 12 is not used. Here, how long it takes to use a refrigerator with a double-door refrigerator door as in the refrigerator 1 is confirmed by an experiment of 21 people. As a result, the average time is about 7 seconds. Considering the result of the discrete difference, if the vacuum pump is activated when the double opening time of the refrigerator compartment doors 2a, 2b elapses after 3 seconds, the refrigerator compartment other than the decompression storage compartment 12 can be used To prevent the wasteful start of the vacuum pump. In addition, when the left-right side-opening method is adopted as in the present embodiment, the door opening/closing time A refers to the time from when any one of the left and right doors is first opened to when the left and right single doors are closed. Figures 8, 9, and 10 are basic control flowcharts when performing decompression. In this flowchart, when the time from the opening of the refrigerator compartment doors 2a, 2b to the closing of the door is more than a specific time, it is considered that the vacuum storage chamber 12 is used to operate the vacuum pump. In addition, when the control is started (step S1), it is assumed that the power is turned on on the premise that the pressure in the decompression storage chamber 12 is near 0 kPa･G. After the power is turned on, the vacuum pump 12 does not operate, so the operation is stopped in step S2. Next, in step S3, the open/close state of the refrigerator compartment doors 2a, 2b is determined. Step S3 has the condition of step S5 (refer to FIG. 9 ), and different actions will be different depending on whether the refrigerator compartment door is a left-right two door (double door) or a single-piece door (single door). In addition, the refrigerator 1 is a refrigerator with two left and right doors that open to the refrigerator compartment door. (Refrigerator 1 is a refrigerator equipped with left and right doors of refrigerator compartment doors 2a, 2b. The following flowchart also corresponds to the control of a refrigerator with a single door.) The flowchart of a refrigerator with double doors will be described below. In steps S6 to S9 (see FIG. 9), when the refrigerator compartment doors 2a, 2b are double-opened, the time during which the refrigerator compartment doors 2a, 2b are double-opened (count i) is measured. After that, it is determined in step S15 that the time i is counted, and if it is less than A seconds, the number i is redesigned in step S16 and the vacuum pump is not operated. When the count i time of step S15 is A second or more, it is considered that there is opening and closing of the door 12a of the decompression storage room 12, and it progresses to step S17 and the number i time is redesigned. In addition, the reason for counting the time when the refrigerator compartment doors 2a, 2b are double-opened is because it is necessary to open the refrigerator compartment doors 2a, 2b and open the decompressed storage when the refrigerator 1 and the decompressed storage compartment 12 are opened and closed to take out food. The door 12a of the compartment 12 pulls out the tray of the decompression storage room, takes out the food, returns to the tray, and closes the door 12a of the decompression storage room, and closes the refrigerator compartment doors 2a, 2b, etc. In the case of the storage room 12, the time is longer. In addition, the decompression storage room 12 of this embodiment is provided in an area spanning both sides of the refrigerator compartment doors 2a, 2b, so that the door 12a of the decompression storage compartment is opened and closed, and either one of the refrigerator compartment doors 2a, 2b has Necessary to open. Assuming that it is a small decompression storage room and is accommodated in the area on the back side of one of the refrigerator compartment doors, it is sufficient to consider the one of the refrigerator compartment doors. In steps S18 to S23, the refrigerator compartment doors 2a, 2b become double-closed, and the measurement of the count ii (the vacuum pump 14 operation waiting time count) is started. The reason for setting "count ii" (counting the waiting time for the operation of the vacuum pump 14) is to prevent the number of operations of the vacuum pump 14 from increasing when the refrigerator compartment doors 2a, 2b are frequently opened and closed in a short time during cooking. When the door of the refrigerator compartment 2a, 2b is opened during counting ii, the number ii is redesigned and counting ii is restarted. In step S24, it is confirmed that the refrigerator compartment doors 2a, 2b, the ice making compartment door 3a, the second freezer compartment door 5a, the first freezer compartment door 4a, and the vegetable compartment door 6a of the refrigerator 1 are all closed, and the vacuum pump 14 is started in step S25. Operation, starting from step S26, the measurement of the technique number iii (counting the operation time of the vacuum pump 14) is performed. Steps S26-44 are the control when the vacuum pump 14 is operating. In step S27, when the temperature of the refrigerating room becomes 45°C or higher (when the temperature of the refrigerating room temperature sensor 17 senses 45°C or higher), the operation of the vacuum pump is stopped in order to prevent the operating temperature range of the vacuum pump 14 from being exceeded. In steps S28 to S34, the opening and closing of the doors of the refrigerator compartment doors 2a, 2b, ice-making compartment door 3a, second freezer compartment door 5a, first freezer compartment door 4a, and vegetable compartment door 6a of the refrigerator 1 are monitored in count iii, When any door is opened, the operation of the vacuum pump 14 is stopped, and the count iii is stopped. In step S33 (refer to FIG. 10), the refrigerator compartment doors 2a and 2b are monitored (the same as steps S4 to S14 in FIG. 9). In the case of double doors, the time for double opening of the refrigerator compartment doors 2a, 2b (count i) is measured in steps S6 to S9. Then, in step S35, it is judged that the count i time is counted. When the count i time is A seconds or more, the door 12a of the decompression storage compartment 12 is deemed to be opened and closed. In steps S36, 37, the numbers iii and i are redesigned, and the process moves to step S35. The count iii of S18 (the count of the waiting time for the operation of the vacuum pump 14) starts. In step S35, if the count i is less than A seconds, in step S38, redesign the number i, and in step S39, it is determined whether the count iii is stopped (open the refrigerator compartment doors 2a, 2b of the refrigerator 1, the ice compartment door 3a, and the second freezer compartment If any of the door 5a, the first freezer compartment door 4a, and the vegetable compartment door 6a, the vacuum pump 14 is stopped in step S31), when it is stopped, the vacuum pump 14 is operated in steps S40 and S41. Count iii starts again. That is, in the case of the double-opening refrigerator compartment doors 2a, 2b, as long as the double-opening time of the refrigerator compartment doors 2a, 2b does not reach A seconds, the vacuum pump 14 and the counter are stopped at the time when either of the refrigerator compartment doors 2a, 2b is opened iii. Wait until the refrigerator compartment doors 2a, 2b become double-closed and start the operation and counting of the vacuum pump 14 again iii. After the vacuum pump 14 has operated for C seconds, the counting iii ends and resets in steps S43 and 44, the design number i is reset in step S16, and the operation of the vacuum pump is stopped in step S2. As described above, after the pressure in the decompression storage chamber 12 reaches the decompression target pressure, as long as the user does not open the decompression storage chamber door 12a, the pressure in the decompression storage chamber 12 is maintained at a low pressure. However, it is difficult to achieve a structure in which the space including the vacuum pump 14, the duct 13, and the decompression storage chamber 12 is completely sealed, and minute air leakage (air leakage) may occur. Here, as also disclosed in FIG. 5 described above, as long as air leaks from the outside of the decompression storage chamber 12 to the inside, the internal pressure will gradually increase, and finally return to 0 kPa･G (atmospheric pressure) (refer to the dotted line in FIG. 11 ). FIG. 11 starts the operation of the vacuum pump 14 (the state of the vacuum pump "ON: operation") in the aforementioned flowchart, and then continues to operate for only C seconds (C time). That is, in FIG. 11, the vertical axis indicates the pressure state in the decompression storage chamber 12, and further below, the ON/OFF state of the vacuum pump 14 is displayed. According to this, as described above, even if the volume of the decompression storage chamber 12 fluctuates, the pressure of the decompression storage chamber 12 is reduced gradually to a specific pressure (= decompression target pressure). After that, after stopping the operation for only a specific time (D time), it is presumed that the pressure in the decompression storage chamber 12 will return to the pressure necessary for decompression (target upper limit pressure) (air leakage), and here, again The operation of the vacuum pump 14 is started. In addition, the operation time (E time) of the vacuum pump 14 necessary for depressurizing from the target upper limit pressure to the depressurization target pressure can be set in advance in the same manner as described above. Next, by repeating this operation, the pressure in the decompression storage chamber 12 can be maintained at a desired low pressure without detecting the pressure in the decompression storage chamber 12. That is, by setting the operation time of the vacuum pump 14 based on the internal volume of the decompression storage chamber 12 and the decompression target pressure of the decompression storage chamber 12, by a relatively simple control method that only controls the operation time of the vacuum pump, It is possible to realize a highly reliable refrigerator with a low-pressure compartment at a low cost without using a pressure switch. FIG. 12 is a timing chart for the description of double opening determination of the refrigerator compartment doors 2a, 2b of the flowcharts of FIGS. 8, 9, and 10 and the time D and E of FIG. 11. The opening time of the refrigerator compartment door (shown as the refrigerator compartment door in FIG. 12, but the double-opening doors are both the refrigerator compartment doors 2a and 2b, and the single-piece door is 1 refrigerator compartment door) is T0 <A (the judgment time of counting i) In this case, the vacuum pump 14 does not operate. The opening time of the refrigerator compartment door (shown as the refrigerator compartment door in FIG. 12, but the double-opening doors are both the refrigerator compartment doors 2a, 2b, and the single-piece door is 1 refrigerator compartment door) is T0≧A (the judgment time of counting i) In this case, the decompression storage compartment door 12a regarded as the decompression storage compartment 12 is opened and closed, and the vacuum pump 14 starts to operate after the operation wait time B seconds of the vacuum pump 14. Also, as shown in FIG. 12, when the time for the double opening of the refrigerator compartment doors 2a, 2b is T0≧A (the determination time of counting i), regardless of whether the vacuum storage compartment door 12a of the vacuum storage compartment 12 opens or closes the vacuum pump 14 Operation. In addition, after the operation of the vacuum pump 14 continues within the time D, and the double-opening time of the refrigerator compartment doors 2a, 2b does not reach T0≧A (the judgment time of counting i), consider the air leakage as described above, so that the vacuum pump 14 Operation E time. In addition, in this control, when the operation continues within the aforementioned D time and the double-opening time of the refrigerator compartment doors 2a, 2b does not reach T0≧A (the judgment time of the count i), because the pressure has been reduced to some extent, A short time to reach the decompression target pressure is sufficient. Here, the operation time of the vacuum pump 16 is C time>E time, and the life expectancy of the vacuum pump 14 is increased by not causing unnecessary operation. Fig. 13 is the determination of the opening of the refrigerator compartment doors 2a, 2b when the vacuum pump 14 in the flow chart of Figs. 8, 9, and 10 is operated (shown as the refrigerator compartment door in Fig. 13, but the double-open door is a single unit of the refrigerator compartment doors 2a, 2b In the case where the single-piece door is a refrigerator compartment door, the timing chart for the supplementary explanation. When the double-opening time of the refrigerator compartment doors 2a, 2b is T0≧A (the judgment time of counting i), the decompressed storage compartment door 12a regarded as the decompressed storage compartment 12 is opened and closed, and the vacuum pump 14 is operated as described above. During the operation of the vacuum pump 14, the refrigerator compartment door of the refrigerator 1 (in the case of double doors, it is a single side of the refrigerator compartment doors 2a, 2b, and the single-slice door is one of the refrigerator compartment doors), the ice-making compartment door 3a, and the second freezing When any of the compartment door 5a, the first freezer compartment door 4a, and the vegetable compartment door 6a is opened, the operation of the vacuum pump 14 is stopped. If the double opening time of the refrigerator door (double door is 2a, 2b of the refrigerator door, and the single door is 1 door of the refrigerator door) is T2 <A (the judgment time of counting i), all the doors of the refrigerator 1 will be closed again. The operation of the vacuum pump 14 is started. In addition, the operation time of the vacuum pump 14 is C=C1+C2 (total operation C time). Refrigerating compartment door (in case of double door, both sides of refrigerating compartment door 2a, 2b, single-piece door is one piece of refrigerating compartment door), when the time of double opening is T2≧A (the judgment time of counting i), it is regarded as decompression storage room 12 The vacuum storage compartment door 12a is opened and closed, regardless of the operation time C3 before the vacuum pump 14 stops, and the vacuum pump 14 is operated for C time after the operation wait time of the vacuum pump 14 is B seconds. By the above method, the refrigerator 1 provided with the decompression storage compartment 12 whose internal pressure is decompressed inside the main body can be realized at a low cost by relatively simple control without using a pressure switch The refrigerator 1 of the reduced-pressure storage compartment 12 with high reliability can further achieve the effect of extending the life of the vacuum pump 14 or eliminating air leakage accompanying the installation of the pressure detection means. Next, a description will be given of other embodiments (second embodiment) in which the excessive vacuum pump is turned on without using a pressure switch and the decompression operation in the decompression storage chamber 12 is performed. Figure 14 is a control block diagram. Symbol 17 is a temperature sensor that detects the temperature in the refrigerator compartment 2, symbol 15 is a microcomputer mounted on a refrigerator control board (not shown), symbol 20a is a display LED incorporated into the operation panel 20, and symbol 14b is The DC motor driving the vacuum pump 14. The detection signals of the refrigerator compartment door switch 7, the decompression storage compartment door switch 21, and the refrigerator compartment temperature sensor 17 are input to the microcomputer 15, and output signals are output to the display LED 20a and the vacuum pump 14 (DC motor 14b) according to the control specifications described later. Composition. In addition, the current signal room 14c represents the signal of the motor current of the DC motor 14b, and the signal is fed back to the microcomputer 15. In addition, the current signal 14c fed back to the microcomputer 15 is amplified by the current discharge circuit 22 mounted on the control board of the refrigerator, so that the minute current increase and decrease can be detected with higher accuracy. Next, FIG. 15 shows the pressure state inside the decompression storage chamber 12 when the vacuum pump 14 continues to operate, and the state of the current signal 14c. The horizontal axis is the operation time from when the vacuum pump 14 starts to operate, and the vertical axis shows the pressure in the decompression storage chamber 12 and the level of the current signal 14c. In this specification, the pressure value is a gauge pressure, and its unit is expressed in kPa･G. That is, atmospheric pressure = 0kPa･G, which is a negative value when it is lower than it. When the vacuum pump 14 is connected to the reduced-pressure storage chamber 12 and operated, according to the experiments of the inventors, when the vacuum pump 14 is started as shown in FIG. 15, the pressure gradually decreases as time passes. Here, the vacuum pump 14 of the present embodiment is used in which the decompression capacity is not less than -30 kPa･G. By using such a pump, when the volume of the decompression storage chamber 12 is different, that is, when the amount of air sucked is different, and the vacuum pump 14 uses the same pump, the smaller the volume, the faster the pressure drop rate should be, but In this embodiment, the pressure inside the decompression storage chamber 12 should not be lower than -30 kPa･G. On the other hand, the current signal 14c increases the current value as the pressure in the low-pressure chamber decreases. This phenomenon is due to the characteristics of the DC motor 14b used as the power source of the vacuum pump 14. The DC motor has a characteristic that the motor load is proportional to the motor current, so as the air pressure in the low-pressure chamber decreases, the motor load increases, and the current value also increases. When is below a certain pressure, the work capacity of the pump mechanism decreases (it becomes impossible to reduce pressure), so the motor load is reduced and the motor current is reduced. In the aforementioned refrigerator, the timing chart shown in FIG. 16 and the flowchart shown in FIG. 17 are used to explain the control of detecting that the pressure in the decompression storage chamber 12 is below a certain pressure by a vacuum pump without a switch for detecting pressure. specification. First, the decompression storage compartment 12 is accommodated inside the refrigerator compartment 2, and it is determined whether the vacuum pump 7 is turned on by whether the refrigerator compartment door 2a is opened or closed. In this embodiment, the vacuum pump is turned on only when the time until the refrigerator door 2a is opened (S001) and closed (S002) is more than 3s. (S003). When the opening and closing time is less than 3s, the vacuum pump is kept off (S004), and when it is more than 3s, the vacuum pump 7 is turned on (S005). Here, the basis for operating the vacuum pump, that is, the door opening time of 3 seconds is explained. When opening and closing the decompression storage room door 12a of the decompression storage room 12 to take out and put in the food, you must go through the opening of the refrigerator compartment door 2a (the left and right doors in the case of a double door with a left and right opening) and open the decompression storage room door 12a. Pull out the tray, take out the food, return to the tray, and close the decompressed storage compartment door 12a, and close the refrigerator compartment door 2a. A series of procedures are longer than when the decompressed storage compartment 12 is not used. Here, how long it takes to use a refrigerator with a double-door refrigerator door is confirmed based on an experiment by 21 people. As a result, the average time is about 7 seconds. Considering the result of discrete differences, if the vacuum pump is activated when the double-opening time of the refrigerator compartment door has passed 3 seconds, it is possible to prevent waste when using a refrigerator compartment other than the decompression storage compartment 12 To start the vacuum pump. During the opening of the vacuum pump, it is detected whether the refrigerator compartment door is opened or closed (S006). If there is, the low-pressure detection control is ended. After the refrigerator door is closed, the vacuum pump is turned on until the third specific time (t3), and the operation is ended (S007). Here, the third specific time (t3) is set to a time during which the pressure inside the decompression storage chamber 12 is between -15 and -20 kPa･G, and is set to a value of 150 s or the like in the present embodiment. The third specific time (t3) changes with the volume of the decompression storage compartment 12, and it is necessary to change the set time with the volume, for example, 150 s for 20L and 75 s for 10L. When the first specific time (t1) elapses without the opening and closing of the refrigerator compartment door, the first current value (I1) at that time is measured (S008). As shown in the timing chart of FIG. 16, after the DC motor 14b is turned on, a current much larger than the normal current (surge current) flows. In order not to be erroneously detected, the first specific time passes after the vacuum pump 14 is turned on After (t1), the first current value (I1) is measured. The surge current is approximately several ms to several hundreds ms, and in this embodiment, the first specific time is set to 10 s. Then, when there is no opening or closing of the refrigerator compartment door 2a until the second specific time (t2), the second current value (I2) is measured (S011). When the refrigerator compartment door is opened and closed before the second specific time (t2), the low-pressure detection control is ended, and after the refrigerator door is closed, the vacuum pump is turned on until the third specific time (t3) to end the operation. (S010) Here, the second specific time (t2) is set to a time shorter than the third specific time (t3), whereby the inside of the decompression storage chamber 12 is already under low pressure and no further decompression is necessary , The operation of the excess vacuum pump 14 can be suppressed. As mentioned above, the DC motor 14b increases or decreases the current value according to the motor load. Therefore, in order to sufficiently ensure the pressure change range, the second specific time is preferably as long as possible. However, in order to suppress the activation of the excess vacuum pump 14, it is necessary to adopt the shortest possible time. In this embodiment, the second specific time (t2) is set to 30 to 70% of the third specific time (t3). For example, when the third specific time (t3) is set to a low-pressure chamber capacity of 150 s, the third specific time is set to 75 s. Calculate the difference (S012) between the first current value (I1) and the second current value (I2), and compare the result (⊿I) with 0kPa･G (atmospheric pressure) and the threshold value (X) for determining low pressure (S013). ⊿I<X, the pressure in the decompression storage chamber 12 is judged as low pressure, and the vacuum pump 14 is turned off. (S014). ⊿I≧X, the pressure in the decompression storage chamber 12 is judged to be 0 kPa･G (atmospheric pressure), and the vacuum pump 14 is continuously turned on until the third specific time (t3). (S015) According to the above control specifications, the pressure in the decompression storage chamber 12 is estimated by the current of the DC motor 14b, and the wasteful operation of the vacuum pump 14 can be suppressed. By this, by determining the pressure in the decompression storage chamber 12 without using a pressure switch, it is possible to provide a highly reliable refrigerator with reduced leakage. In addition, the term “leakage” herein refers to a sealed space in a decompressed storage room or a vacuum pump, which allows air to be kept in a sealed space from a gap in the sealed space due to the pressure difference between the decompressed sealed space and the sealed space. Next, with further implementation forms (third implementation form), description will be given of implementations that, with simpler control, suppress the opening of an excessive vacuum pump without using a pressure switch and perform a decompression operation in the decompression storage chamber 12 state. In addition, the component configuration is the same as in the second embodiment. The timing chart of this embodiment is shown in FIG. 18, and the flowchart is shown in FIG. First, for the operations from S016 to S022, the same operations as S01 to S07 described in the second embodiment are performed. After starting the vacuum pump 14 (S020) and continuing to operate until the fourth specific time, the fourth current value (I4) at that time is measured (S023). Compare the first current value (I1) with the low pressure judgment value Y (S024). If I1 <Y, it is judged as low pressure, and the vacuum pump 14 is turned off (S025), if I1 ≧ Y, it is judged as 0 kPa･G (atmospheric pressure), and the vacuum pump 14 continues to operate Until the third specific time (t3) (S026). Here, in the refrigerator of the present embodiment, the fourth specific time is set to a time within a range of 50% or less of the third specific time. As described above, in the DC motor 14b used as the power source of the vacuum pump 14, the motor current is increased in proportion to the increase in the motor load. When the fourth specific time is set to be longer than 50% of the third specific time, decompression from 0kPa･G (atmospheric pressure) will also increase the current, and there is no clear difference from the case of decompression from low pressure. Become difficult. The transition of the current signal in this state is shown in Figure 20. As shown in FIG. 20, when the vacuum pump is started from 0 kPa･G (atmospheric pressure), and when the vacuum pump is started from a low pressure, the fourth current value (I4) is larger than Y and becomes indiscernible. On the other hand, when the fourth specific time is 50% or less of the third specific time, the fourth current value (I4) when the vacuum pump is started from 0 kPa･G (atmospheric pressure) is lower than the low pressure judgment value Y, 0 kPa･ The determination of G (atmospheric pressure) and low pressure is possible. The transition of the current signal in this state is shown in Figure 21. With the above control, it is possible to provide a refrigerator with a simpler control structure and determining the pressure in the decompression storage compartment 12 without using a pressure switch. (Fourth Embodiment) Next, a method of determining whether the pressure in the decompression storage chamber 12 is 0 kPa･G (atmospheric pressure) or low pressure by the rotation speed of the DC motor 14b will be described. First, FIG. 22 shows a characteristic diagram of a general DC motor. The vertical axis shows the current [I] and the rotation speed [min＾-1], and the horizontal axis shows the torque [mNm], which indicates the weight of the load applied to the motor. According to the characteristic diagram shown in FIG. 22, the current [I] increases proportionally with the increase of torque, and the rotation speed [min＾-1] has a proportional characteristic. In the second and third embodiments, the low-voltage detection method using this current [I] will be described. In this embodiment, the method of detecting low voltage with the rotation speed [min-1] will be described. The timing chart of low-pressure detection control using the rotation speed [min-1-1] is shown in FIG. 23, and the flowchart is shown in FIG. 24. Hereinafter, the operation will be described using FIGS. 23 and 24. The control flow is the same as S001 to S015 shown in the second embodiment, but the detection target is changed from current to rotation speed. As in the second embodiment, when the first rotation speed (N1) and the second rotation speed (N2) are measured and the difference ⊿N (S038) is calculated, and ⊿N<Z, the pressure in the decompression storage chamber 12 is determined as The vacuum pump 14 is turned off at a low pressure. (S014) When ⊿N≧Z, the pressure in the decompression storage chamber 12 is judged to be 0 kPa･G (atmospheric pressure), and the vacuum pump 14 is continuously turned on until the third specific time (t3). (S041) By the above operation, the pressure in the decompression storage chamber 12 is estimated from the rotation speed of the DC motor 14b, and wasteful operation of the vacuum pump 14 can be suppressed. By this, by determining the pressure in the decompression storage compartment 12 without using a pressure switch, it is possible to provide a highly reliable refrigerator with reduced leakage. As a means of detecting the rotation speed of the DC motor 14b, in the case of a DC brush motor, it can be obtained from the frequency of the motor current. In addition, in the case of a DC brushless motor, there are those who output a rotation speed signal (FG signal) on the built-in drive substrate, which can be used to detect the rotation speed. In any motor, when the low-voltage detection is performed by the rotation speed, the current amplifier circuit 22 is not necessary, so a cheaper low-voltage detection specification can be realized.
