JP4107053B2 - Evaporative fuel processing device for internal combustion engine - Google Patents

Description

【０１６１】
以上説明した通り、本実施形態の装置は、車両の駐車中に異常検出の実行が要求された場合に、通常制御の実行に先立って、その実行中に蒸発燃料の吹き抜けが生ずる可能性があるか否かを適切に判断することができる。そして、その可能性がない場合に限って通常制御を実行し、その可能性がある場合には、異常検出自体を中止することができる。このため、本実施形態の装置によれば、異常検出の実行に伴ってキャニスタ２６から蒸発燃料が吹き抜けるのを有効に防ぐことができる。
【０１６２】
ところで、上述した実施の形態１では、蒸発燃料処理装置の異常検出を、負圧法により実行することを前提としている。異常検出が負圧法により行われる場合、蒸発燃料の吹き抜けは、既述した通り、封鎖弁２８が閉から開に切り換えられた場面、およびポンプ７４によりキャニスタ２６内のガスが吸い出される場面において生じ得る。このため、本実施形態において、上記ステップ２７４，２９０および３００で用いられる所定値は、それら２つの場面の何れにおいても蒸発燃料の吹き抜けを生じさせない値に設定されている。
【０１６３】
これに対して、本実施形態の装置では、異常検出の手法として、負圧法に代えて正圧法を用いることが可能である。異常検出が正圧法により行われる場合、蒸発燃料の吹き抜けが生ずる場面が封鎖弁２８の開弁時に限られる。このため、異常検出の手法として正圧法が用いられる場合は、上記ステップ２７４，２９０および３００で用いられる所定値は、封鎖弁２８の開弁時において蒸発燃料の吹き抜けを生じさせない値に設定されればよい。
【０１６４】
尚、上述した実施の形態１においては、負圧ポンプモジュール５２が前記第１の発明における「差圧形成手段」に、上記ステップ１３０の処理により封鎖弁２８をONとする処理が前記第１の発明における「封鎖弁開弁処理」に、φ０．５リークチェック処理が前記第１の発明における「差圧形成処理」および「リーク検査処理」に、それぞれ相当している。そして、ECU６０が、上記図６乃至図１１に示すルーチンを実行することにより前記第１の発明における「通常処理実行手段」が、上記図１２乃至図１３に示すルーチンのうち少なくとも１つを実行することにより前記第１の発明における「吹き抜け可能性判断手段」が、上記ステップ１１２および１１６の処理を実行することにより前記第１の発明における「通常処理禁止手段」が、それぞれ実現されている。
【０１６５】
また、上述した実施の形態１においては、ECU６０に、図１２乃至図１４に示すルーチンにより、封鎖弁２８の開弁に伴って蒸発燃料が吹き抜ける可能性があるか否かを判断させることにより、前記第２の発明における「開弁時吹き抜け可能性判断手段」を実現することができる。
【０１６６】
また、上述した実施の形態１においては、ポンプ７４によりキャニスタ２６内のガスが吸い出される場面で蒸発燃料の吹き抜けが生ずる可能性があるか否かが判断されるようにECU６０が上記図１２乃至図１４に示すルーチンを実行することで、前記第３の発明における「負圧形成時吹き抜け可能性判断手段」が実現されている。
【０１６７】
また、上述した実施の形態１においては、ECU６０が、上記ステップ１１２および１１６の処理を実行することにより前記第４の発明における「リーク検出中止手段」が実現されている。
【０１６８】
実施の形態２．
次に、図１５乃至図２０を参照して、本発明の実施の形態２について説明する。
本実施形態の蒸発燃料処理装置は、実施の形態１の場合と同様に、図１に示す構成により実現することができる。また、本実施形態において、ECU６０は、実施の形態１の場合と同様に、図３に示すECU通電判定ルーチンおよび図５に示すECU電源遮断判定ルーチンを実行し、更に、図１２乃至図１４に示すHC吹き抜け発生判定ルーチンの少なくとも１つを実行する。そして、本実施形態の装置は、ECU６０に、それらのルーチンと共に、後述する図１５乃至図２０に示すルーチンを実行させることにより実現することができる。
【０１６９】
上述した実施の形態１の装置は、通常制御の実行に伴って蒸発燃料が吹き抜ける可能性がある場合は、異常検出自体を中止することで、その吹き抜けを防止することとしている。ところで、このような蒸発燃料の吹き抜けは、通常制御の実行中に封鎖弁２８が開かれることにより発生する。従って、吹き抜けの可能性があると判断された場合であっても、封鎖弁２８さえ開かなければ、蒸発燃料の吹き抜けは防ぐことができる。そこで、本実施形態では、通常制御の実行に伴って蒸発燃料が吹き抜ける可能性があると判断される場合は、封鎖弁２８を閉じたままキャニスタ２６側だけを対象として異常検出を実行する。以下、この異常検出のための処理を「キャニスタリーク検出処理」と称す。
【０１７０】
［キャニスタリーク検出処理の説明］
以下、図１５を参照して、ECU６０の通電が開始された後、蒸発燃料の吹き抜けが生ずる可能性があると判断された場合に実行されるキャニスタリーク検出処理の内容について説明する。
【０１７１】
ECU６０は、内蔵するソークタイマにより所定時間（例えば５時間）が計数されると、異常検出処理を開始するため、図１５に示すように起動される（時刻T1）。封鎖弁２８は、車両の駐車中は原則として閉じられている。このため、図１５（Ｅ）中に破線で示すように、ECU６０が起動される時点で、通常はタンク内圧Ptが正圧または負圧となっている。
【０１７２】
時刻T1の後、ECU６０の内部では、通常制御の実行に伴って蒸発燃料の吹き抜けが生ずる可能性があるか否かが判断される。その結果、吹き抜けの可能性があると判断された場合は、封鎖弁２８が閉じられたまま「大気圧判定処理」が開始される（時刻T2）。時刻T2の時点では、切り替え弁８０がOFF状態とされているため、ポンプモジュール圧センサ８６の周囲に大気圧が導かれている。このため、ECU６０は、時刻T2の後、ポンプモジュール圧Pcが安定しているのを確認して、その時点におけるPcを大気圧相当値として認識する。以後、ECU６０は、そのPc（大気圧相当値）に基づいて、ポンプモジュール圧センサ８６の較正処理を実行する。
【０１７３】
キャニスタリーク検出処理は、封鎖弁２８が閉じられたままの状態で行われる。つまり、キャニスタリーク検出処理は、燃料タンク１０からキャニスタ２６へ蒸発燃料が流出してこない状況下で、キャニスタ２６の洩れを検出するために実行される。この場合、燃料タンク１０の内部で蒸発燃料がどのように発生していても洩れ検出の精度には影響が生じない。このため、キャニスタリーク検出処理では、通常制御において実行される「エバポ量判定処理」（図２参照）が省略され、大気圧判定処理の後、速やかに「φ０．５REF穴チェック処理」が開始される（時刻T3）。
【０１７４】
図１５（Ｃ）に示すように、時刻T3では、ポンプ７４が作動状態とされる。この時点では切り替え弁８０がOFFとされているため、ポンプ７４の吸入口は、逆止弁７６および基準オリフィス８４を介して大気に連通している。従って、ポンプ７４がONされると、ポンプモジュール圧センサ８６の出力は、配管に０．５mmの基準穴が空いている状況下で、ポンプ７４が作動しているのと同等の値（負圧値）に収束する。
【０１７５】
ECU６０は、時刻T3の後、ポンプモジュール圧Pcが適当な値に収束するのを待って、その収束値をφ０．５穴判定値として記憶する。以後、このφ０．５穴判定値は、キャニスタ２６に０．５mmの基準穴を超える洩れが生じているか否かを判断するための判定値として用いられる。
【０１７６】
通常処理では、「φ０．５REF穴チェック処理」に次いで、封鎖弁２８の開閉を伴う「封鎖弁OBD処理」が実行される。キャニスタリーク検出処理は、封鎖弁２８を閉じたまま進める必要があるため、その途中で、封鎖弁OBD処理を実行することはできない。このため、キャニスタリーク検出処理では、「φ０．５REF穴チェック処理」の終了後、「封鎖弁OBD処理」の実行が省略され、速やかに「φ０．５穴リークチェック処理」が開始される（時刻T4）。
【０１７７】
ECU６０は、時刻T4において、切り替え弁８０をONとする。切り替え弁８０がONとされると、キャニスタ２６の大気孔が大気から切り放されて、キャニスタ２６内のガスがポンプ７４により吸引され始める。キャニスタ２６に洩れが生じていない場合は、ポンプモジュール圧Pcがφ０．５穴判定値より小さな値に収束する。一方、キャニスタ２６に洩れが生じている場合は、Pcがφ０．５穴判定値まで減少しない。
【０１７８】
従って、ECU６０は、時刻T4の後、適当な時間が経過する以前にPcがφ０．５穴判定値より小さな値になれば、キャニスタ２６に洩れが生じていないと判断することができる。また、その条件が成立しなかった場合は、キャニスタ２６に基準穴を超える洩れが生じていると判断することができる。
【０１７９】
φ０．５穴リークチェック処理が終了すると、その時点でポンプ７４がOFFされ（時刻T5）、その後適当な時間が経過した時点で「パージVSVOBD処理」が開始される（時刻T6）。ECU６０は、時刻T6においてパージVSV３６に対して開弁指令を発する。この処理によりパージVSV３６が適正に開弁すると、キャニスタ２６の密閉が破られ、ポンプモジュール圧Pcは上昇し始める。一方、パージVSV３６が適正に開弁しない場合は、Pcに何ら有意な変化は生じない。ECU６０は、時刻T6の後、ポンプモジュール圧Pcに十分な変化が認められる場合は、パージVSV３６が閉状態から開状態に適正に変化したと判断し、一方、Pcにその変化が認められない場合は、パージVSV３６が適正に開弁していない、つまり、パージVSV３６に閉故障が生じているとの判断を下す。
【０１８０】
パージVSVOBD処理が終了すると、キャニスタリーク検出処理が終了する（時刻T7）。ECU６０は、この時点で、全ての機構をOFF状態とする。その結果、蒸発燃料処理装置は、車両の駐車中における通常の状態、つまり、時刻T1の状態に復帰する。以後、適当な時間が経過した時点で、ECU６０は停止状態となる（時刻T8）。
【０１８１】
以上説明した通り、本実施形態の蒸発燃料処理装置によれば、図１５に示すタイムチャートに沿った処理、すなわち、キャニスタリーク検出処理を実行することにより、封鎖弁２８を閉じたまま、蒸発燃料の大気への吹き抜けを生じさせることなく、キャニスタ２６を含む系に洩れが存在するか否かを判断することができる。
【０１８２】
［ECUが実行する具体的処理の説明］
以下、ECU６０が、本実施形態において実行する具体的処理の内容について説明する。
ECU６０は、車両の駐車中は、実施の形態１の場合と同様に図３に示すECU通電判定ルーチンを繰り返し実行する。その結果、ソークタイマにより所定値が計数されると、ECU６０を本格的に起動させるための通電が開始される。
【０１８３】
ECU６０は、また、上記の如く通電が開始された後、実施の形態１の場合と同様に、図５に示すECU電源遮断判定ルーチンを繰り返し実行する。そして、KEY OFFモニタ作動フラグがOFFとされると、その時点で通電を遮断してスタンバイ状態に移行する。
【０１８４】
図１６は、本実施形態において、ECU６０が、異常検出の実行に関する前提条件が成立可否に合わせてKET OFFモニタ作動フラグを処理するために実行する前提条件判定ルーチンのフローチャートである。図１６に示すルーチンは、ステップ１１２が省略されている点を除き、実施の形態１において実行される図４に示すルーチンと同様である。
【０１８５】
図１６に示すルーチンによれば、ステップ１１０において、所定の前提条件（前トリップ走行履歴、吸気温および冷却水温、バッテリ電圧、IGスイッチなどに関する条件）が成立するか否かが判別さえる。その結果、前提条件が成立すると判別される場合は、ステップ１１４においてKEY OFFモニタ作動フラグがONとされる。一方、前提条件が成立しないと判別される場合は、ステップ１１６においてKET OFF作動フラグがOFFとされる。
【０１８６】
上記ルーチンの処理によりKEY OFFモニタ作動フラグがOFFとされると、その後ECU６０の通電が遮断されるため、異常検出の実行が禁止される。これに対して、上記ルーチンの処理によりKEY OFFモニタ作動フラグがONとされる限りは、ECU６０の通電が維持され、以後、異常検出を進めるべく、以下に説明する処理が順次実行される。
【０１８７】
図１７は、ECU６０が、「大気圧判定処理」を実現するために実行する制御ルーチンのフローチャートである。図１７に示すルーチンは、ステップ３１０および３１２が追加されている点、およびステップ１４０がステップ３１４に置き換えられている点を除き、実施の形態１において実行される図６に示すルーチンと同様である。尚、図１７において、図６に示すステップと同一のステップについては、同一の符号を付してその説明を省略または簡略する。
【０１８８】
図１７に示すルーチンでは、先ず、HC吹き抜け発生状態が形成されているか否かが判別される（ステップ３１０）。
ECU６０は、実施の形態１の場合と同様に、その通電が開始された後速やかに、通常処理の実行に伴って蒸発燃料の吹き抜けが生ずる可能性があるか否かを判断し、その判断に従ってHC吹き抜け発生フラグをONまたはOFFとする（図１２乃至図１４参照）。本ステップ３１０では、このようにして処理されたHC吹き抜け発生フラグの状態に基づいて、HC吹き抜け発生状態が形成されているか否かが判別される。
【０１８９】
上記の判別の結果、HC吹き抜け発生状態が形成されていないと判別された場合は、以後、実施の形態１の場合と同様に、ステップ１３０以降の処理が実行される。この場合、図６を参照して説明した場合と同様の手順で「大気圧判定処理」が進められる。
【０１９０】
一方、上記ステップ３１０において、HC吹き抜け発生状態が形成されていると判別された場合は、図１５中時刻T2に示す状態を形成するため、つまり、封鎖弁２８を閉じたまま大気圧判定処理を実行するため、蒸発燃料処理装置の各要素が以下のように制御される（ステップ３１２）。
・切り替え弁８０：OFF
・ポンプ７４：OFF
・封鎖弁２８：OFF（閉）
・パージVSV３６：OFF
尚、本ステップ３１２で実現すべき状態は、時刻T2以前から実現されている。このため、本ステップ３１２では、具体的には、上記各要素の状態は、何ら変更されない。
【０１９１】
上記ステップ３１２により実現される状態によれば、ポンプモジュール圧センサ１２の周囲には、大気圧が導かれる。ECU６０は、以後、ポンプモジュール圧Pcが安定しているのを確認して、その値Pcを大気圧相当値として記憶する（ステップ１３８，１４４）。
【０１９２】
本実施形態では、手順の簡単化を優先して、通常制御とキャニスタリーク検出処理とでステップ１４４を区別しないこととしている。このため、ステップ１４４では、キャニスタリーク検出処理の場合にも、タンク内圧Ptの大気圧相当値が記憶される。キャニスタリーク検出処理の場合は、燃料タンク１０の内部が大気圧に開放されないため、ステップ１４４が実行される時点で、タンク内圧Ptは大気圧相当値にはなっていない。しかしながら、キャニスタリーク検出処理の場合は、タンク内圧Ptが何らの処理にも利用されないため、上記の不一致によっては何ら弊害は生じない。
【０１９３】
図１７に示すルーチン中、上記ステップ１３８において、ポンプモジュール圧Pcおよびタンク内圧Ptの何れかが安定していないと判別された場合は、次に、このルーチンが開始されてからの経過時間が、所定値ＡまたはＢより短いか否かが判別される（ステップ３１４）。
【０１９４】
より具体的には、今回の処理が通常処理の一部として実行されている場合は、上記ステップ３１４において、経過時間＜所定値Ａの成立可否が判別される。ここで用いられる所定値Ａは、図６に示すステップ１４０で用いられる所定値と同じ値である。一方、今回の処理がキャニスタリーク検出処理の一部として行われている場合は、上記ステップ３１４において、経過時間＜所定値Ｂの成立可否が判断される。所定値Ｂは、所定値Ａに比して小さな値である。
【０１９５】
通常処理の場合は、大気圧判定処理の開始時点（図２、時刻t2参照）で、封鎖弁２８が開かれるため、タンク内圧Ptが収束するまでにある程度の時間が必要である。一方、キャニスタリーク検出処理では、大気圧判定処理の開始時点で、ポンプモジュール圧Pcやタンク内圧Ptを変動させる変化は何ら生じない。このため、通常制御の場合とキャニスタリーク検出処理の場合とで所定値Ａ，Ｂを区別することによれば、後者の場合に無駄な待ち時間が生ずるのを防ぐことができる。
【０１９６】
図１７に示すルーチン中、上記ステップ１４４の処理が終了すると、「大気圧判定処理」が終了する。以後、ECU６０は、図１８に示すルーチンを開始する。
図１８は、ECU６０が、「エバポ量判定処理」を実現するために実行するルーチンのフローチャートである。図１８に示すルーチンは、ステップ３２０が追加されている点を除き、実施の形態１において実行される図７に示すルーチンと同様である。尚、図１８において、図７に示すステップと同一のステップについては、同一の符号を付してその説明を省略または簡略する。
【０１９７】
図１８に示すルーチンでは、先ず、HC吹き抜け発生状態が形成されているか否かが判別される（ステップ３２０）。
【０１９８】
その結果、HC吹き抜け発生状態が形成されていないと判別された場合は、以後、実施の形態１の場合と同様に、ステップ１５０以降の処理が実行される。この場合、図７を参照して説明した場合と同じ手順で「エバポ量判定処理」が進められる。
【０１９９】
一方、上記ステップ３２０において、HC吹き抜け発生状態が形成されていると判別された場合は、エバポ量判定処理を実行する必要がないと判断される。この場合、以後、図１８に示すルーチンがジャンプされ、速やかに図１９に示すルーチンが開始される。
【０２００】
図１９は、ECU６０が、「φ０．５REF穴チェック処理」を実現するために実行する制御ルーチンのフローチャートである。図１９に示すルーチンは、ステップ３３０および３３２が追加されている点、並びにステップ１８４の後段にステップ３３４が追加されている点を除き、実施の形態１において実行される図８に示すルーチンと同様である。尚、図１９において、図８に示すステップと同一のステップについては、同一の符号を付してその説明を省略または簡略する。
【０２０１】
図１９に示すルーチンでは、先ず、HC吹き抜け発生状態が形成されているか否かが判別される（ステップ３３０）。
【０２０２】
その結果、HC吹き抜け発生状態が形成されていないと判別された場合は、以後、実施の形態１の場合と同様に、ステップ１７０以降の処理が実行される。この場合、図８を参照して説明した場合と同じ手順で「φ０．５REF穴チェック処理」が進められる。
【０２０３】
一方、上記ステップ３３０において、HC吹き抜け発生状態が形成されていると判別された場合は、図１５中時刻T3に示す状態を形成するため、つまり、ポンプモジュール圧センサ８６の周囲に、φ０．５mmの基準穴の存在を前提とした負圧を発生させるために、蒸発燃料処理装置の各要素が以下のように制御される（ステップ３３２）。
・切り替え弁８０：OFF
・ポンプ７４：ON
・封鎖弁２８：OFF（閉）
・パージVSV３６：OFF
【０２０４】
上記ステップ３３２では、具体的には、大気圧判定処理の終了後、ポンプ７４をONとする処理が実行される。上記の処理によれば、封鎖弁２８を閉じたまま、ポンプモジュール圧センサ７４の周囲にφ０．５mmの基準穴の存在を前提とした負圧を発生させることができる。このため、図１９に示すルーチンによれば、キャニスタリーク検出処理の場合にも、通常処理の場合と同様に、φ０．５穴判定値を正確に検知することができる。
【０２０５】
図１９に示すルーチンでは、φ０．５穴判定値の検出が終了した後（ステップ１８４の処理が終了した後）、再びHC吹き抜け発生状態が形成されているか否かが判別される（ステップ３３４）。
【０２０６】
その結果、HC吹き抜け発生状態が形成されていないと判別された場合は、以後、実施の形態１の場合と同様の手順で「封鎖弁OBD処理」、「φ０．５リークチェック処理」、および「パージVSVOBD処理」が順次行われる（図９乃至図１１参照）。一方、上記ステップ３３４において、HC吹き抜け発生状態が形成されていると判別された場合は、次に、図２０に示すルーチンが開始される。
【０２０７】
図２０は、ECU６０が、キャニスタリーク検出処理の一部として「φ０．５REF穴チェック処理」を実現するために実行する制御ルーチンのフローチャートである。図２０に示すルーチンは、ステップ２４０がステップ３４０に、ステップ２５４がステップ３４２に、また、ステップ２５８がステップ３４４に、それぞれ置き換えられている点を除き、実施の形態１において実行される図１１に示すルーチンと同様である。尚、図２０において、図１１に示すステップと同一のステップについては、同一の符号を付してその説明を省略または簡略する。
【０２０８】
図２０に示すルーチンでは、先ず、図１５中時刻T4に示す状態を形成するため、蒸発燃料処理装置の各要素が以下のように制御される（ステップ３４０）。
・切り替え弁８０：ON
・ポンプ７４：ON
・封鎖弁２８：OFF（閉）
・パージVSV３６：OFF
【０２０９】
上記ステップ３４０では、具体的には、「φ０．５REF穴チェック処理」の終了後、切り替え弁８０をOFFからONとする処理が実行される。切り替え弁８０がONとされると、基準オリフィス８４を介してキャニスタ２６（大気圧）に連通していたポンプモジュール圧センサ８６が、直接的にキャニスタ２６と連通する状態となる。このため、ポンプモジュール圧Pcは、上記ステップ３４０の処理が実行されると同時に瞬間的に大きな値に変化する（時刻T4参照）。
【０２１０】
システムが正常である場合は、以後、適当な時間が経過することにより、ポンプモジュール圧Pcはφ０．５穴判定値より小さな値に低下する。そして、キャニスタリーク検出処理の実行中に「Pc＜φ０．５穴判定値」が成立した場合は、キャニスタ２６が適正に密閉されているとの判断を下すことができる。図２０に示すルーチンでは、ステップ２５０において上記条件の成立が判定されると、以後、上記の判断に従って、キャニスタ２６の洩れ故障、封鎖弁２８の開故障、およびパージVSV３６の開故障について正常判定が成される（ステップ３４４）。
【０２１１】
キャニスタ２６に、φ０．５mmの基準穴を超える洩れが生じている場合は、ポンプモジュール圧Pcが、φ０．５穴判定値を下回ることなく安定値に収束する。そして、キャニスタリーク検出処理の実行中にそのような事態が認められる場合は、キャニスタ２６が適正に密閉されていないとの判断を下すことができる。図２０に示すルーチンでは、ステップ２５２においてポンプモジュール圧Pcの安定値収束が判定されると、以後、上記の判断に従って、キャニスタ２６の洩れ故障、封鎖弁２８の開故障、およびパージVSV３６の開故障について異常判定がなされる（ステップ３４４）。
【０２１２】
以上説明した通り、図１７乃至図２０に示すルーチンによれば、ECU６０の起動時にHC吹き抜け発生状態が形成されている場合には、通常処理に代えてキャニスタリーク検出処理を実行し、封鎖弁２８を閉じたままキャニスタ２６に洩れが生じているか否かを判断することができる。このため、本実施形態の蒸発燃料処理装置によれば、蒸発燃料の大気漏出を実施の形態１の場合と同様に防ぎつつ、キャニスタ２６の洩れ検出に関して、実施の形態１の場合に比して高い実行頻度を確保することができる。
【０２１３】
尚、上述した実施の形態２においては、ECU６０が、図９乃至図１１に示すルーチンと、図１７乃至図２０に示すルーチンとを組み合わせて、図６乃至図１１に示すルーチンと同様の処理を実行することにより前記第１の発明における「通常処理実行手段」が実現されていると共に、上記ステップ３１０、３２０、３３０および３３４の処理を実行することにより前記第１の発明における「通常処理禁止手段」が実現されている。
【０２１４】
また、上述した実施の形態２においては、上記ステップ３４０の処理が前記第５の発明における「第２差圧形成処理」に、上記ステップ２５０および２５２の処理が前記第５の発明における「第２リーク検査処理」にそれぞれ相当していると共に、ECU６０が、図２０に示すルーチンを実行することにより前記第５の発明における「キャニスタリーク検出処理実行手段」が、上記ステップ３３４の処理を実行することにより前記第５の発明における「処理切り換え手段」が、それぞれ実現されている。
【０２１５】
【発明の効果】
この発明は以上説明したように構成されているので、以下に示すような効果を奏する。
第１の発明によれば、キャニスタと燃料タンクの双方を含む系全体の洩れを検査するための通常処理を開始する前に、その通常処理の過程で、キャニスタの大気孔から蒸発燃料が吹き抜ける可能性があるか否かを判断することができる。そして、その可能性があると判断された場合は、通常処理の実行を禁止することができる。このため、本発明によれば、燃料タンクを密閉するための封鎖弁を備える蒸発燃料処理装置において、洩れ検出の実行中に蒸発燃料が大気に放出されるのを確実に防ぐことができる。
【０２１６】
第２の発明によれば、通常処理が実行された場合に、特に封鎖弁の開弁に伴って蒸発燃料が吹き抜ける可能性があるか否かを判断することができる。
【０２１７】
第３の発明によれば、通常処理が実行された場合に、特に負圧形成処理の実行に伴ってキャニスタ内のガスが吸引される過程で、蒸発燃料が大気に放出される可能性があるか否かを判断することができる。
【０２１８】
第４の発明によれば、通常処理の実行に伴う蒸発燃料の吹き抜けが予測される場合に、蒸発燃料処理装置におけるリーク検出処理の実行を中止することで、蒸発燃料の大気放出を確実に防ぐことができる。
【０２１９】
第５の発明によれば、通常処理の実行に伴う蒸発燃料の吹き抜けが予測される場合に、通常処理に代えて、キャニスタを含む系のリークのみを検査する第２リーク検査処理を実行することにより、蒸発燃料の大気放出を確実に防ぐことができる。
【０２２０】
第６の発明によれば、封鎖弁の開弁に伴って燃料タンクからキャニスタに向かって流れるガス流量に基づいて、蒸発燃料が大気孔から吹き抜ける可能性があるか否かを判断することができる。蒸発燃料は、上記のガス流量が多量であるほど大気に吹き抜けやすい。従って、本発明によれば、蒸発燃料が大気に吹き抜ける可能性があるか否かを精度良く推定することができる。
【０２２１】
第７の発明によれば、蒸発燃料が大気孔から吹き抜ける可能性があるか否かをタンク内圧に基づいて判断することができる。封鎖弁の開弁に伴って燃料タンクからキャニスタに向かって流れるガス流量は、その開弁時におけるタンク内圧が高いほど多量となる。従って、本発明によれば、蒸発燃料が大気に吹き抜ける可能性があるか否かを精度良く推定することができる。
【０２２２】
第８の発明によれば、蒸発燃料が大気孔から吹き抜ける可能性があるか否かを、燃料タンク内の空間容積に基づいて判断することができる。封鎖弁の開弁に伴って燃料タンクからキャニスタに向かって流れるガス流量は、その開弁時における燃料タンク内の空間容積が大きいほど多量となる。従って、本発明によれば、蒸発燃料が大気に吹き抜ける可能性があるか否かを精度良く推定することができる。
【０２２３】
第９の発明によれば、キャニスタの蒸発燃料吸着状態に基づいて、蒸発燃料が大気孔から吹き抜ける可能性があるか否かを判断することができる。蒸発燃料は、キャニスタに吸着されている蒸発燃料が多量であるほど大気に吹き抜けやすい。従って、本発明によれば、蒸発燃料が大気に吹き抜ける可能性があるか否かを精度良く推定することができる。
【０２２４】
第１０の発明によれば、給油の際にキャニスタに吸着された給油時吸着量に基づいて、キャニスタの蒸発燃料吸着状態を精度良く推定することができる。
【０２２５】
第１１の発明によれば、キャニスタからパージされた蒸発燃料の積算値、すなわち、積算パージ量に基づいて、キャニスタの蒸発燃料吸着状態を精度良く推定することができる。
【０２２６】
第１２の発明によれば、給油後の積算パージ量を基礎とすることにより、キャニスタの蒸発燃料吸着状態を、極めて精度良く推定することができる。
【図面の簡単な説明】
【図１】 本発明の実施の形態１の構成を説明するための図である。
【図２】 実施の形態１において実行される通常処理の内容を説明するためのタイミングチャートである。
【図３】 実施の形態１において実行されるECU通電判定ルーチンのフローチャートである。
【図４】 実施の形態１においてKEY OFFモニタ作動フラグを処理するために実行されるルーチンのフローチャートである。
【図５】 実施の形態１において実行されるECU電源遮断判定ルーチンのフローチャートである。
【図６】 実施の形態１において実行される大気圧測定ルーチンのフローチャートである。
【図７】 実施の形態１において実行されるエバポ発生量測定ルーチンのフローチャートである。
【図８】 実施の形態１において実行されるREF穴基準圧力測定ルーチンのフローチャートである。
【図９】 実施の形態１において実行される封鎖弁開故障判定ルーチンのフローチャートである。
【図１０】 実施の形態１において実行される封鎖弁閉故障判定ルーチンのフローチャートである。
【図１１】 実施の形態１において実行されるリークチェックルーチンのフローチャートである。
【図１２】 実施の形態１において実行されるHC吹き抜け発生判定ルーチンの第１例のフローチャートである。
【図１３】 実施の形態１において実行されるHC吹き抜け発生判定ルーチンの第２例のフローチャートである。
【図１４】 実施の形態１において実行されるHC吹き抜け発生判定ルーチンの第３例のフローチャートである。
【図１５】 本発明の実施の形態２において実行されるキャニスタリーク検出処理の内容を説明するためのタイミングチャートである。
【図１６】 実施の形態２においてKEY OFFモニタ作動フラグを処理するために実行されるルーチンのフローチャートである。
【図１７】 実施の形態２において実行される大気圧測定ルーチンのフローチャートである。
【図１８】 実施の形態２において実行されるエバポ発生量測定ルーチンのフローチャートである。
【図１９】 実施の形態２において実行されるREF穴基準圧力測定ルーチンのフローチャートである。
【図２０】 実施の形態２においてキャニスタリーク検出処理の一部として実行されるリークチェックルーチンのフローチャートである。
【符号の説明】
１０ 燃料タンク
１２ タンク内圧センサ
１４ 液面センサ
２４ 封鎖弁ユニット
２８ 封鎖弁
２６ キャニスタ
３６ パージVSV
５２ 負圧ポンプユニット
６０ ECU(Electronic Control Unit)
７４ ポンプ
８０ 切り替え弁
８６ ポンプモジュール圧センサ
Pc ポンプモジュール圧（ポンプモジュール圧センサの出力）
Pt タンク内圧（タンク内圧センサの出力）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an evaporated fuel processing apparatus, and more particularly to an evaporated fuel processing apparatus for processing evaporated fuel generated in a fuel tank without releasing it into the atmosphere.
[0002]
[Prior art]
Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-294052, an evaporative fuel processing apparatus including a canister communicating with a fuel tank is known. This device includes a block valve disposed in a path connecting the fuel tank and the canister. The blockade valve is opened in a situation where the flow of evaporated fuel in the fuel tank should be allowed, such as during refueling. In this case, the evaporated fuel flowing out from the fuel tank is adsorbed by the canister. The evaporated fuel adsorbed by the canister is purged into the intake passage of the internal combustion engine when a predetermined purge condition is satisfied. As a result, the evaporated fuel generated in the fuel tank is processed as fuel without being released into the atmosphere.
[0003]
The conventional apparatus has a function of determining whether or not leakage has occurred in the apparatus by the following method. That is, after the internal combustion engine is started, this device first detects the tank internal pressure in a state where the block valve is closed. When the tank internal pressure obtained as a result is a value near atmospheric pressure, the blockade valve is opened, and leak detection is performed for the entire system including both the fuel tank and the canister. On the other hand, if the tank internal pressure detected with the blockade valve closed is a predetermined positive pressure or negative pressure, it is first determined at that time that no leakage has occurred in the fuel tank. Thereafter, it is inspected whether or not leakage has occurred in the system on the canister side with the block valve closed. According to such a method, after the internal combustion engine is started, it is possible to quickly and accurately detect whether there is an abnormality in the fuel tank alone.
[0004]
[Patent Document 1]
JP 2001-294052 A
[0005]
[Problems to be solved by the invention]
Incidentally, in the above-described conventional apparatus, the closing valve is opened regardless of the state of the fuel tank or the fuel adsorption state of the canister. If the blockade valve is opened under a situation where a large amount of evaporated fuel is present in the fuel tank or when a large amount of evaporated fuel is adsorbed to the canister, the evaporated fuel that flows into the canister as the valve is opened A situation may occur in which the air flows through the canister and flows out to the atmosphere. For this reason, in the above conventional apparatus, it was not possible to reliably prevent the evaporated fuel from being released into the atmosphere during the leak detection.
[0006]
The present invention has been made to solve the above-described problems, and includes a block valve for sealing a fuel tank, and ensures that evaporated fuel is released into the atmosphere during leak detection. It is an object of the present invention to provide an evaporative fuel processing apparatus that can prevent the problem.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a first invention is an evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
A blocking valve for controlling a conduction state between the fuel tank and the canister;
A purge control valve for controlling a conduction state of a purge passage communicating the canister and the internal combustion engine;
A differential pressure forming means provided in the atmospheric hole of the canister and generating a differential pressure inside and outside the canister;
A closing valve opening process for opening the closing valve from the closed state to the opening state when the purge control valve is closed, and a pressure difference between the inside and outside of the canister when the purge control valve is closed and the closing valve is opened. A differential pressure forming process for operating the differential pressure generating means so as to cause a leak, and a leak inspection process for inspecting a leak of a system including both the canister and the fuel tank in conjunction with the execution of the differential pressure forming process. Normal processing execution means for executing normal processing including:
Prior to the start of the normal processing, in the course of the normal processing, a blow-through possibility determination means for determining whether or not evaporative fuel may blow through the atmospheric hole of the canister,
Normal processing prohibiting means for prohibiting execution of the normal processing when it is determined that there is a possibility that the evaporated fuel may blow through in the normal processing;
It is characterized by providing.
[0008]
In addition, according to a second aspect, in the first aspect, the blow-through possibility determination means determines whether or not the evaporated fuel may blow through the atmospheric hole of the canister when the blockade valve opening process is executed. The valve opening possibility judgment means for judging the valve opening is included.
[0009]
The third invention is the first or second invention, wherein
The differential pressure forming process includes a negative pressure forming process in which gas is sucked from the atmospheric hole to make the inside of the canister a negative pressure,
The blow-through possibility determination means includes a negative-pressure formation blow-through possibility determination means that determines whether or not the evaporated fuel may blow through the atmospheric hole of the canister during the execution of the negative pressure formation process. Features.
[0010]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the normal processing prohibiting unit includes a leak detection stopping unit that stops execution of the leak detection processing in the evaporated fuel processing apparatus. And
[0011]
According to a fifth invention, in any one of the first to third inventions,
Execution of a second differential pressure forming process for operating the differential pressure generating means so that a differential pressure is generated inside and outside the canister while the purge control valve and the blocking valve are closed, and the second differential pressure forming process And a canister leak detection process executing means for executing a canister leak detection process including a second leak inspection process for inspecting a leak of the system including the canister,
The normal process prohibiting means includes a process switching means for executing the canister leak detection process instead of the normal process.
[0012]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the blow-through possibility determination means is configured to provide a gas flow rate that flows from the fuel tank toward the canister when the blocking valve is opened. On the basis of the above, it is determined whether or not there is a possibility that the evaporated fuel may blow through the air hole.
[0013]
According to a seventh aspect, in the sixth aspect, the blow-through possibility determining means includes tank internal pressure detecting means for detecting a tank internal pressure, and the tank internal pressure is increased with the opening of the sealing valve. It is used as a characteristic value of the gas flow rate flowing out from the tank toward the canister.
[0014]
According to an eighth aspect of the present invention, in the sixth or seventh aspect, the blow-through possibility determination means includes a spatial volume detection means for detecting a spatial volume in the fuel tank, and the spatial volume is determined by the sealing valve. It is used as a characteristic value of the flow rate of gas flowing out from the fuel tank toward the canister when the valve is opened.
[0015]
In a ninth aspect based on the first to eighth aspects, the blow-through possibility determination means determines whether the evaporated fuel may blow through the atmospheric hole based on the evaporated fuel adsorption state of the canister. It is characterized by judging.
[0016]
The tenth invention is the ninth invention, wherein
Oil supply control means for opening the block valve during refueling,
The blow-through possibility determination means includes a fuel-adsorption amount estimation means that estimates the amount of evaporated fuel that flows into the canister from the fuel tank and is adsorbed to the canister during refueling, as the fuel-absorption amount. The time adsorption amount is used as a characteristic value of the evaporated fuel adsorption state.
[0017]
The eleventh aspect of the invention is the ninth or tenth aspect of the invention,
A purge control means for opening the purge control valve and purging the evaporated fuel in the canister toward the internal combustion engine when a predetermined purge condition is satisfied;
The blowout possibility determination means includes
An integrated purge amount calculating means for calculating an integrated value of the evaporated fuel purged from the canister as an integrated purge amount;
The integrated purge amount is used as a characteristic value of the evaporated fuel adsorption state.
[0018]
In a twelfth aspect based on the eleventh aspect, the blow-through possibility determining means includes post-refueling integrated purge amount calculating means for calculating an integrated purge amount after refueling, and the integrated purge amount after refueling is calculated from the It is used as a characteristic value of the evaporated fuel adsorption state.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.
[0020]
Embodiment 1 FIG.
[Description of device configuration]
FIG. 1A is a diagram for explaining the configuration of the fuel vapor processing apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1A, the apparatus of this embodiment includes a fuel tank 10. The fuel tank 10 is provided with a tank internal pressure sensor 12 for measuring the tank internal pressure Pt. The tank internal pressure sensor 12 is a sensor that detects a tank internal pressure Pt as a relative pressure with respect to the atmospheric pressure and generates an output corresponding to the detected value. A liquid level sensor 14 for detecting the liquid level of the fuel is disposed inside the fuel tank 10.
[0021]
A vapor passage 20 is connected to the fuel tank 10 via ROV (Roll Over Valve) 16 and 18. The vapor passage 20 includes a block valve unit 24 in the middle thereof, and communicates with the canister 26 at the end thereof. The block valve unit 24 includes a block valve 28 and a relief valve 30. The block valve 28 is a normally closed electromagnetic valve that closes in a non-energized state and opens when a drive signal is supplied from the outside. The relief valve 30 includes a forward relief valve that opens when the pressure on the fuel tank 10 side is sufficiently higher than the pressure on the canister 26 side, and a reverse relief valve that opens in the opposite case. This is a mechanical two-way check valve. The valve opening pressure of the relief valve 30 is set, for example, to about 20 kPa in the forward direction and about 15 kPa in the reverse direction.
[0022]
The canister 26 includes a purge hole 32. A purge passage 34 communicates with the purge hole 32. The purge passage 34 includes a purge VSV (Vacuum Switching Valve) 36 in the middle of the purge passage 34 and communicates with an intake passage 38 of the internal combustion engine at the end thereof. An air filter 40, an air flow meter 42, a throttle valve 44, and the like are provided in the intake passage 38 of the internal combustion engine. The purge passage 34 communicates with the intake passage 38 downstream of the throttle valve 44.
[0023]
The inside of the canister 26 is filled with activated carbon. The evaporated fuel flowing in through the vapor passage 20 is adsorbed by the activated carbon. The canister 26 also has an air hole 50. An atmospheric passage 54 communicates with the atmospheric hole 50 via a negative pressure pump module 52. The air passage 54 includes an air filter 56 in the middle thereof. The end of the atmospheric passage 54 is open to the atmosphere in the vicinity of the fuel filler port 58 of the fuel tank 10.
[0024]
As shown in FIG. 1A, the evaporated fuel processing apparatus of this embodiment includes an ECU 60. The ECU 60 incorporates a soak timer for counting the elapsed time while the vehicle is parked. A lid switch 62 and a lid opener opening / closing switch 64 are connected to the ECU 60 together with the tank internal pressure sensor 12, the sealing valve 28, or the negative pressure pump module 52 described above. The lid opener opening / closing switch 64 is connected to a lid manual opening / closing device 66 by a wire.
[0025]
The lid opener opening / closing switch 64 is a locking mechanism for a lid (vehicle body lid) 68 that covers the fuel filler opening 58. When a lid opening signal is supplied from the ECU 60, or when the lid manual opening / closing device 66 is opened to a predetermined extent. When the operation is performed, the lid 68 is unlocked. The lid switch 62 connected to the ECU 60 is a switch for sending a command for releasing the lock of the lid 68 to the ECU 60.
[0026]
FIG. 1B is an enlarged view for explaining details of the negative pressure pump module 52 shown in FIG. The negative pressure pump module 52 includes a canister-side passage 70 that communicates with the air hole 50 of the canister 26 and an atmosphere-side passage 72 that communicates with the atmosphere. A pump passage 78 including a pump 74 and a check valve 76 communicates with the atmosphere side passage 72.
[0027]
The negative pressure pump module 52 also includes a switching valve 80 and a bypass passage 82. The switching valve 80 communicates the canister-side passage 70 with the atmosphere-side passage 72 in a non-energized state (OFF state), and pumps the canister-side passage 70 in a state where an external drive signal is supplied (ON state). The passage 78 is communicated. The bypass passage 82 is a passage through which the canister-side passage 70 and the pump passage 78 are electrically connected, and a 0.5 mm diameter reference orifice 84 is provided in the middle thereof.
[0028]
The negative pressure pump module 52 further incorporates a pump module pressure sensor 86. According to the pump module pressure sensor 86, the pressure inside the pump passage 78 can be detected on the check valve 76 side of the check valve 76.
[0029]
[Description of basic operation]
Next, the basic operation of the evaporated fuel processing apparatus of this embodiment will be described.
(1) Parking
In principle, the fuel vapor processing apparatus of the present embodiment maintains the closing valve 28 in a closed state while the vehicle is parked. When the blocking valve 28 is closed, the fuel tank 10 is cut off from the canister 26 as long as the relief valve 30 is closed. Therefore, in the evaporated fuel processing apparatus of the present embodiment, the evaporated fuel is newly adsorbed to the canister 26 while the vehicle is parked unless the tank internal pressure Pt exceeds the forward valve opening pressure (20 kPa) of the relief valve 30. There is nothing. In addition, as long as the tank internal pressure Pt does not fall below the reverse valve opening pressure (−15 kPa) of the relief valve 30, air is not sucked into the fuel tank 10 while the vehicle is parked.
[0030]
(2) Refueling
In the apparatus of the present embodiment, when the lid switch 62 is operated while the vehicle is stopped, the ECU 60 is activated, and first, the closing valve 28 is opened. At this time, if the tank internal pressure Pt is higher than the atmospheric pressure, the block valve 28 opens, and at the same time, the evaporated fuel in the fuel tank 10 flows into the canister 26 and is adsorbed by the activated carbon therein. As a result, the tank internal pressure Pt decreases to near atmospheric pressure.
[0031]
When the tank internal pressure Pt decreases to near atmospheric pressure, the ECU 60 issues a command to the lid opener 64 to release the lock of the lid 68. The lid opener 64 receives the command and releases the lock of the lid 68. As a result, in the apparatus of the present embodiment, the lid 68 can be opened after the tank internal pressure Pt reaches a value near atmospheric pressure.
[0032]
When the opening operation of the lid 68 is permitted, the lid 68 is opened, then the tank cap is opened, and then fuel supply is started. Since the tank internal pressure Pt is reduced to near atmospheric pressure before the tank cap is opened, the evaporated fuel is not released from the fuel filler port 58 to the atmosphere in accordance with the opening operation.
[0033]
The ECU 60 keeps the blocking valve 28 in an open state until refueling is completed (specifically, until the lid 68 is closed). For this reason, when refueling, the gas in the tank can flow out to the canister 26 through the vapor passage 20, and as a result, good refueling properties are ensured. At this time, the evaporative fuel flowing out is adsorbed by the canister 26 and therefore is not released to the atmosphere.
[0034]
(3) Running
During traveling of the vehicle, control for purging the evaporated fuel adsorbed by the canister 26 is executed when a predetermined purge condition is satisfied. Specifically, in this control, the purge VSV 36 is appropriately driven with a duty while the switching valve 80 is turned off and the atmospheric hole of the canister 26 is opened to the atmosphere. When the purge VSV 36 is driven with a duty, the intake negative pressure of the internal combustion engine 10 is guided to the purge hole 32 of the canister 26. As a result, the evaporated fuel in the canister 26 is purged into the intake passage 38 of the internal combustion engine together with the air sucked from the air hole 50.
[0035]
Further, during traveling of the vehicle, the closing valve 28 is appropriately opened so that the tank internal pressure Pt is maintained in the vicinity of the atmospheric pressure for the purpose of shortening the pressure releasing time before refueling. However, the valve opening is performed only during the purge of the evaporated fuel, that is, only when the intake negative pressure is introduced into the purge hole 32 of the canister 26. Under the condition that intake negative pressure is introduced to the purge hole 32, the evaporated fuel flowing from the fuel tank 10 into the canister 26 flows out of the purge hole 32 without entering deeply into the canister 26, and then purges into the intake passage 38. Is done. Therefore, according to the apparatus of the present embodiment, a large amount of evaporated fuel is not newly adsorbed to the canister 26 while the vehicle is traveling.
[0036]
As described above, according to the evaporated fuel processing apparatus of the present embodiment, in principle, the evaporated fuel to be adsorbed by the canister 26 can be limited to only evaporated fuel that flows out of the fuel tank 10 during refueling. For this reason, according to the apparatus of the present embodiment, it is possible to realize a good exhaust emission and a good oil supply property while reducing the size of the canister 26.
[0037]
[Description of abnormality detection operation]
The evaporative fuel processing apparatus is required to have a function for promptly detecting an abnormality that leads to deterioration of emission characteristics, such as occurrence of leakage in the system or an abnormality of the block valve 28. Hereinafter, with reference to FIG. 2, the content of the abnormality detection process which the apparatus of this embodiment performs in order to implement | achieve said function is demonstrated.
[0038]
FIG. 2 is a timing chart for explaining the contents of the abnormality detection process executed by the apparatus of this embodiment. In the present embodiment, the abnormality detection process is executed while the vehicle is parked from the viewpoint of minimizing the influence of various disturbances.
[0039]
The ECU 60 has a built-in soak timer as described above. When a predetermined time (for example, 5 hours) is counted by the soak timer, the abnormality detection process is started, and the ECU is activated as shown in FIG. 2 (time t1). The device of this embodiment closes the closing valve 28 in principle while the vehicle is parked. For this reason, as indicated by a broken line in FIG. 2E, the tank internal pressure Pt is normally positive or negative at the time when the ECU 60 is activated.
[0040]
When the ECU 60 is activated, first, as shown in FIG. 2A, the block valve 28 is changed from the closed state to the open state (time t2). When the blocking valve 28 is opened, the inside of the fuel tank 10 is opened to the atmosphere, so that the tank internal pressure Pt subsequently changes to a value near atmospheric pressure as shown in FIG.
[0041]
In the apparatus of the present embodiment, both the pump 74 and the switching valve 80 of the negative pressure pump module 52 are in the OFF state at the time t2. In this case, since the atmospheric pressure is introduced into the pump passage 78, the output of the pump module pressure sensor 86 has a value corresponding to the atmospheric pressure.
[0042]
As described above, when the blocking valve 28 is opened at time t2, the output of the tank internal pressure sensor 12 and the output of the pump module pressure sensor 86 both become atmospheric pressure equivalent values. For this reason, the ECU 60 recognizes these sensor outputs as atmospheric pressure equivalent values, and executes calibration processing of the tank internal pressure sensor 12 and the pump module pressure sensor 86 based on the atmospheric pressure equivalent values. In the present embodiment, this calibration process is referred to as “atmospheric pressure determination process”.
[0043]
When the atmospheric pressure determination process ends, the switching valve 80 is then switched from the OFF state to the ON state as shown in FIG. 2B (time t3). Since the purge VSV 36 is closed at this stage, when the switching valve 80 is turned on, the system including the canister 26 and the fuel tank 10 becomes a sealed space. In this case, both the output of the tank internal pressure sensor and the output of the pump module pressure sensor 86 show changes in accordance with the generation state of the evaporated fuel in the fuel tank 10 or the liquefied state of the evaporated fuel (FIG. 2 ( E) and the broken line in FIG. 2 (F)).
[0044]
Therefore, after turning on the switching valve at time t3, the ECU 60 generates the evaporated fuel in the fuel tank 10 (or liquefaction state) based on the output of the tank internal pressure sensor 12 or the output of the pump module pressure sensor 86. ). Hereinafter, in the present embodiment, this estimation process is referred to as “evaporation amount determination process”.
[0045]
When the evaporation amount determination process is completed, the switching valve 80 is then returned from the ON state to the OFF state as shown in FIG. 2 (B), and the pump 74 is turned ON as shown in FIG. 2 (C). (Time t4). When the switching valve 80 is returned to the OFF state, a state is formed in which the suction port of the pump 74 communicates with the atmosphere via the check valve 76 and the reference orifice 84. Therefore, in this case, the output of the pump module pressure sensor 86 converges to a value (negative pressure value) equivalent to that when the pump 74 is operating under the condition that the pipe has a 0.5 mm reference hole. .
[0046]
After time t4, the ECU 60 waits for the output Pc of the pump module sensor 86 (hereinafter referred to as “pump module pressure Pc”) to converge to an appropriate value as shown in FIG. The value is stored as a φ0.5 hole judgment value. Thereafter, the φ0.5 hole determination value is used as a determination value for determining whether or not leakage exceeding the 0.5 mm reference hole has occurred in the evaporated fuel processing apparatus. Hereinafter, in the present embodiment, the above-described process for detecting the φ0.5 hole determination value is referred to as “φ0.5REF hole check process”.
[0047]
When the φ0.5REF hole check process is completed, the blocking valve 28 is switched from the open state to the closed state as shown in FIG. 2 (A), and the switching valve 80 is turned off as shown in FIG. 2 (B). The state is switched to the ON state (time t5). When the switching valve 80 is turned on, the canister 26 is disconnected from the atmosphere and communicated with the suction port of the pump 74. As a result, the internal pressure of the canister 26 is reduced, and the pump module pressure Pc gradually becomes negative.
[0048]
If the blocking valve 28 is properly closed, the negative pressure accompanying the operation of the pump 74 is guided only to the canister 26. Therefore, in this case, after time t5, the pump module pressure Pc changes rapidly. On the other hand, when the blocking valve 28 is not properly closed, the negative pressure associated with the operation of the pump 74 is guided not only to the canister 26 but also to the fuel tank 10, so that the pump module pressure Pc is increased after time t5. Shows a gradual decrease (see FIG. 2F).
[0049]
Therefore, if the pump module pressure Pc decreases rapidly after time t5, the ECU 60 determines that the blocking valve 28 is properly closed, while if the decreasing tendency is moderate, It is determined that the closing valve 28 is not properly closed, that is, an open failure has occurred in the closing valve 28.
[0050]
After determining whether or not an open failure has occurred in the sealing valve 28 (time t6), the ECU 60 issues a valve opening command to the sealing valve 28 as shown in FIG. As a result, when the shutoff valve 28 properly changes from the closed state to the open state, the gas in the fuel tank 10 flows into the canister 26, so the pump module pressure Pc changes to a large value in a stepwise manner. To do. On the other hand, when the blocking valve 28 does not open properly, no significant change occurs in the pump module pressure Pc (see FIG. 2F).
[0051]
Therefore, when a sufficient change in the pump module pressure Pc is recognized after time t6, the ECU 60 determines that the block valve 28 has properly changed from the closed state to the open state, while the pump module pressure Pc is increased to the pump module pressure Pc. When the change is not recognized, it is determined that the closing valve 28 is not properly opened, that is, the closing valve 28 is closed.
[0052]
As described above, in the apparatus of the present embodiment, it is possible to determine whether or not an open failure has occurred in the blocking valve 28 based on whether or not the pump module pressure Pc decreases rapidly after time t5. In addition, after time t6, it can be determined whether or not a closing failure has occurred in the blocking valve 28 based on whether or not a significant change occurs in the pump module pressure Pc. Hereinafter, in the present embodiment, the process for making the above determination is referred to as “blocking valve OBD process”.
[0053]
When the closing valve 28 is properly opened at time t6, the canister 26 and the fuel tank 10 are sealed at that time. Then, as the pump 74 is operated, both the internal pressure of the canister 26 and the internal pressure of the fuel tank 10 begin to be reduced. When there is no leakage in both the canister 26 and the fuel tank 10, the pump module pressure Pc and the tank internal pressure Pt both converge to a value smaller than the φ0.5 hole determination value. On the other hand, when leakage occurs in at least one of the canister 26 and the fuel tank 10, neither Pc nor Pt decreases to the φ0.5 hole determination value.
[0054]
Therefore, in the apparatus of this embodiment, if Pc or Pt becomes a value smaller than the φ0.5 hole judgment value before an appropriate time has elapsed after time t6, there is no leakage in the entire system. Judgment can be made. If the condition is not satisfied, it can be determined that a leak exceeding the reference hole has occurred in any part of the system. Hereinafter, in the present embodiment, the process for making the above determination is referred to as “φ0.5 hole leak check process”.
[0055]
When the φ0.5 hole leak check process ends, the pump 74 is turned off as shown in FIG. 2C (time t7). Thereafter, after an appropriate time, the purge VSV 36 is opened as shown in FIG. 2D (time t8). When the purge VSV 36 is properly opened by this processing, the system including the canister 26 and the fuel tank 10 is hermetically sealed, and thereafter, the pump module pressure Pc and the tank internal pressure Pt tend to increase. On the other hand, when the purge VSV 36 does not open properly, no significant change occurs in Pc and Pt (see FIGS. 2E and 2F).
[0056]
Therefore, when a sufficient change in the pump module pressure Pc or the tank internal pressure Pt is recognized after time t8, the ECU 60 determines that the purge VSV 36 has properly changed from the closed state to the open state, while Pc and When the change is not recognized in Pt, it is determined that the purge VSV 36 is not properly opened, that is, the purge VSV 36 is closed. Hereinafter, in the present embodiment, the process for making the above determination is referred to as “purge VSVOBD process”.
[0057]
When the purge VSVOBD process ends, a series of abnormality detection processes end (time t9). At this time, the ECU 60 turns off all the mechanisms. As a result, the evaporated fuel processing apparatus returns to the normal state during parking of the vehicle, that is, the state before time t2. Thereafter, when an appropriate time elapses, the ECU 60 is stopped (time t10).
[0058]
As described above, according to the evaporated fuel processing apparatus of the present embodiment, a failure of the blocking valve 28 is performed by performing the processing according to the time chart shown in FIG. 2 (hereinafter, this processing is referred to as “normal processing”). Detection, system leak detection, and purge VSV failure detection can be performed sequentially.
[0059]
[Necessity to prevent fuel vapor from blowing through]
By the way, according to the normal process described above, it is necessary to open the closed valve 28 at time t2 and time t6. When such a valve opening operation is performed under the condition that the tank internal pressure Pt is positive, the block valve 28 is opened, and at the same time, the evaporated fuel confined in the fuel tank 10 flows out toward the canister 26. Will happen. If the outflow amount at that time is excessive, the canister 26 cannot adsorb all the evaporated fuel, and a situation may occur in which the evaporated fuel blows through the air holes 50.
[0060]
In the normal process shown in FIG. 2, the gas in the canister 26 needs to be sucked out by the pump 74 during the period from time t5 to time t7. If the gas in the canister 26 is sucked out by the pump 74 in a state where the canister 26 adsorbs a large amount of the evaporated fuel, the evaporated fuel adsorbed on the activated carbon is purged, and as a result, the evaporated fuel is returned to the atmosphere. May occur.
[0061]
In the apparatus of the present embodiment, in order to obtain good emission characteristics, the execution of the normal processing shown in FIG. 2 is prohibited in a situation where the evaporated fuel may blow through the atmospheric hole 50 as described above. It is preferable to prevent blow-through. Therefore, when the execution of abnormality detection is requested, the apparatus according to the present embodiment determines whether or not the evaporated fuel may be blown out during the execution of the normal process before starting the normal process. However, the normal process is executed only when there is no such possibility.
[0062]
[Contents of characteristic processing executed by ECU]
FIG. 3 is a flowchart of an ECU energization determination routine executed by the ECU 60 in order to detect the execution timing of the abnormality detection process while the vehicle is parked. As a premise that this routine is executed, the ECU 60 starts counting up the soak timer from the time when the vehicle shifts to the parking state.
[0063]
When the vehicle is parked, ECU 60 enters a standby state in which only the soak timer counts up and the routine shown in FIG. 3 can be executed. The routine shown in FIG. 3 is repeatedly activated every predetermined time while the vehicle is parked. In this routine, first, it is determined whether or not the count value of the soak timer matches a predetermined value (step 100).
The condition of this step 100 is established when, for example, about 5 hours elapses after the vehicle is parked.
[0064]
If it is determined that the condition of step 100 is not satisfied, the current processing cycle is immediately terminated thereafter. On the other hand, when it is determined that this condition is satisfied, energization processing for operating the ECU 60 in earnest is executed (step 102).
[0065]
FIG. 4 is a flowchart of a control routine executed by the ECU 60 to process the KEY OFF monitor operation flag after energization of the ECU 60 is started by the process of step 102. In this embodiment, the KEY OFF monitor operation flag is a flag used to indicate whether or not to continue energization of the ECU 60, as will be described later.
[0066]
In the routine shown in FIG. 4, first, it is determined whether or not a precondition for performing abnormality detection of the evaporated fuel processing apparatus is satisfied (step 110).
In the present embodiment, as described above, abnormality detection of the evaporated fuel processing device is performed while the vehicle is parked. For this reason, as a precondition, it is confirmed that the ignition switch (IG switch) is off. In this embodiment, it is necessary to operate the pump 74 in the process of detecting an abnormality. For this reason, as a precondition, it is confirmed whether or not the battery voltage is an appropriate value. Furthermore, it is desirable to avoid performing abnormality detection in an extreme environment in order to prevent erroneous determination. For this reason, as a precondition, it is confirmed whether the previous trip travel history (travel history before shifting to the parking state) is not extreme, or whether the current intake air temperature and water temperature are not extreme (extremely low temperature).
[0067]
If it is determined in step 110 that the precondition is satisfied, it is then determined whether or not an “HC blow-off occurrence state” is formed (step 112).
When the ECU 60 starts energization, first, when the normal process shown in FIG. 2 is executed, whether or not the evaporated fuel may blow through the atmospheric hole 50 of the canister 26 in the course of the execution. Judging. Based on the result of the determination, the HC blow-off occurrence flag is processed. The processing method of the HC blow-off occurrence flag will be described in detail later with reference to FIGS.
[0068]
The routine shown in FIG. 4 is executed after the HC blow-off occurrence flag is processed by any of the routines shown in FIGS. Then, in this step 112, based on the state of the HC blow-off occurrence flag, it is determined whether or not there is a possibility that the vaporized fuel will blow through, that is, whether or not an HC blow-off occurrence state is formed.
[0069]
In the routine shown in FIG. 4, if it is determined in step 112 that the HC blow-off occurrence state is not formed, processing for turning on the KEY OFF monitor operation flag is executed (step 114).
[0070]
On the other hand, if it is determined in step 110 that the precondition is not satisfied, and if it is determined in step 112 that the HC blow-off occurrence state is formed, the KEY OFF monitor is activated. The flag is turned off (step 116).
[0071]
FIG. 5 is a flowchart of a control routine executed by the ECU 60 to shut off the power of the ECU 60 when the KEY OFF monitor operation flag is turned OFF.
In the routine shown in FIG. 5, it is first determined whether or not the KEY OFF monitor operation flag is in the OFF state (step 120).
[0072]
As a result, when it is determined that the KEY OFF monitor operation flag is not in the OFF state, the current processing cycle is ended while the energization of the ECU 60 is maintained. On the other hand, when it is determined that the KEY OFF monitor operation flag is in the OFF state, the ECU 60 is again set to the standby state, and thus the main power supply of the ECU 60 is shut off (step 122), and this routine is terminated.
[0073]
As described above, according to the routines shown in FIGS. 3 to 5, when energization of the ECU 60 is started so as to detect abnormality of the evaporated fuel processing apparatus, the blow-through of the fuel is performed along with the execution of the normal processing. It is possible to promptly determine whether or not there is a possibility of occurrence, that is, whether or not an HC blow-off occurrence state is formed. If it is determined that the HC blow-through occurrence state has been formed, it is possible to block the energization of the ECU 60 and prohibit the execution of abnormality detection. For this reason, according to the configuration of the present embodiment, the sealing valve 28 for sealing the fuel tank 10 is provided, and it is possible to reliably prevent the evaporated fuel from being released into the atmosphere during the execution of the abnormality detection. An evaporative fuel processing apparatus can be provided.
[0074]
[Details of normal processing]
The ECU 60 maintains the energized state until the KEY OFF monitor operation flag is turned off after the energization starts in the process of step 102. Then, as long as the energized state is maintained, the ECU 60 executes routines shown in FIGS. 6 to 11 described below in order to proceed with the normal processing shown in FIG.
[0075]
FIG. 6 is a flowchart of a control routine executed by the ECU 60 in order to realize the “atmospheric pressure determination process”.
In the routine shown in FIG. 6, first, in order to form the state shown at time t2 in FIG. 2, that is, in order to open both the tank internal pressure sensor 12 and the pump module pressure sensor 86 to the atmosphere, each element of the evaporated fuel processing device. Are controlled as follows (step 130).
・ Switching valve 80: OFF
・ Pump 74: OFF
・ Blockade valve 28: ON (open)
・ Purge VSV36: OFF
[0076]
When the above processing is completed, it is next determined whether or not the timer should be initialized (step 132).
When this step 132 is executed for the first time after the ECU 60 starts energization, it is determined that the initialization setting should be executed. In this case, next, the timer is initialized (count value reset) (step 134).
On the other hand, if the present step 132 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 136).
[0077]
In the routine shown in FIG. 6, it is next determined whether or not the tank internal pressure Pt and the pump module pressure Pc are stable. More specifically, it is determined whether or not the change amount ΔPt of the tank internal pressure Pt and the change amount ΔPc of the pump module pressure Pc from the previous processing cycle to the current processing cycle are smaller than predetermined determination values, respectively. (Step 138).
[0078]
As a result of the above determination, if it is determined that Pc and Pt are not yet stable, the elapsed time from the start of this routine, that is, the elapsed time counted by the timer is predetermined. It is determined whether the value is shorter than the value (step 140).
[0079]
As a result, if it is determined that the elapsed time is still shorter than the predetermined value, the processes after step 130 are repeated. On the other hand, if it is determined that the elapsed time is already greater than or equal to the predetermined value, it is determined that there is an inappropriate situation in proceeding with normal processing, and the KEY OFF monitor operation flag is turned OFF ( Step 142).
[0080]
If the system is in a normal state, the pump module pressure Pc and the tank internal pressure Pt are both stabilized at a value corresponding to the atmospheric pressure before the elapsed time reaches a predetermined value. In this case, the condition of step 138 is satisfied when Pc and Pt are stabilized. In the routine shown in FIG. 6, when the condition of step 138 is satisfied, the pump module pressure Pc at that time is stored as the output of the pump module pressure sensor 86 corresponding to the atmospheric pressure, and the tank internal pressure Pt at that time is It is stored as the output of the tank internal pressure sensor 12 representing the atmospheric pressure (step 144).
[0081]
When the ECU 60 completes the “atmospheric pressure measurement process” according to the routine shown in FIG. 6, thereafter, the output of the pump module pressure sensor 86 and the output of the tank internal pressure sensor are output using Pc and Pt stored in step 144. Calibrate. For convenience of explanation, description of execution of calibration is omitted, but in the following description, the pump module pressure Pc and the tank internal pressure Pt each mean values after calibration.
[0082]
When the process of step 144 is completed, the routine shown in FIG. 7 is then executed. FIG. 7 is a flowchart of a routine that the ECU 60 executes in order to realize the “evaporation amount determination process”.
[0083]
In the routine shown in FIG. 7, first, in order to form the state shown at time t3 in FIG. 2, that is, to make the system including the fuel tank 10 and the canister 26 into a sealed space, each element of the evaporative fuel processing apparatus is (Step 150).
・ Switching valve 80: ON
・ Pump 74: OFF
・ Blockade valve 28: ON (open)
・ Purge VSV36: OFF
Specifically, after the “atmospheric pressure determination process” is completed, a process of turning the switching valve 80 from OFF to ON is executed.
[0084]
When the above processing is completed, it is next determined whether or not to initialize the timer (step 152).
When this step 152 is executed for the first time after energization of the ECU 60 is started, it is determined that the initialization setting should be executed. In this case, a process for initializing the timer (step 154) and a process for storing the pump module pressure Pc at that time as the initial pressure (step 156) are sequentially executed.
On the other hand, if the present step 152 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 158).
[0085]
Next, in the routine shown in FIG. 7, the elapsed time from the start of the routine, that is, the elapsed time counted by the timer exceeds a predetermined value defined as the execution period of the evaporation amount determination process. It is determined whether or not (step 160).
[0086]
As a result, when it is determined that the elapsed time has not yet exceeded the predetermined value, the processing after step 150 is repeated again. If it is determined that the elapsed time has exceeded a predetermined value, the difference (Pc−initial pressure) between the pump module pressure Pc at that time and the initial pressure stored in step 156 is a predetermined determination value. It is determined whether or not it is smaller (step 162).
[0087]
When it is determined that “Pc−initial pressure <predetermined value” does not hold, it can be determined that the pump module pressure Pc has increased significantly during the evaporation amount determination process. In this case, it can be determined that a large amount of evaporated fuel is generated inside the fuel tank 10.
[0088]
Abnormality detection of the evaporated fuel processing apparatus should not be performed under the situation where a large amount of evaporated fuel is generated in order to avoid erroneous detection. According to the routine shown in FIG. 7, when it can be determined that a large amount of evaporated fuel is generated in the fuel tank 10 by the process of step 162, the KEY OFF monitor operation flag is subsequently turned OFF (step S1). 164).
[0089]
When the KEY OFF monitor operation flag is turned OFF, the ECU 60 is powered off as described above, and the execution of normal processing is stopped. Therefore, according to the routine shown in FIG. 7, it is possible to avoid the abnormality detection of the evaporated fuel processing device from being continued in a situation where a large amount of evaporated fuel is generated.
[0090]
In the routine shown in FIG. 7, if it is determined in step 162 that “Pc−initial pressure <predetermined value” is established, it can be determined that the generation amount of the evaporated fuel is not so large. In this case, the routine shown in FIG. 8 is subsequently executed in order to proceed with normal processing.
[0091]
By the way, in the routine shown in FIG. 7, the generation amount of the evaporated fuel is estimated based on the change in the pump module pressure Pc (see steps 156 and 162), but the estimation method is limited to this. is not. That is, the amount of evaporated fuel may be estimated based on the change in the tank internal pressure Pt.
[0092]
FIG. 8 is a flowchart of a routine executed by the ECU 60 in order to realize the “φ0.5REF hole check process”.
In the routine shown in FIG. 8, first, in order to form the state shown at time t4 in FIG. 2, that is, around the pump module pressure sensor 86, a negative pressure is generated on the premise that a φ0.5 mm reference hole exists. Therefore, each element of the fuel vapor processing apparatus is controlled as follows (step 170).
・ Switching valve 80: OFF
・ Pump 74: ON
・ Blockade valve 28: ON (open)
・ Purge VSV36: OFF
Specifically, after the “evaporation amount determination process” is completed, a process of turning the switching valve 80 from ON to OFF and turning the pump 74 ON is executed.
[0093]
When the above processing is completed, it is next determined whether or not the timer should be initialized (step 172).
When this step 172 is executed for the first time after the start of energization of the ECU 60, it is determined that the initialization setting should be executed. In this case, next, a process for initializing the timer is executed (step 174).
On the other hand, if the present step 172 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 176).
[0094]
In the routine shown in FIG. 8, it is next determined whether or not the pump module pressure Pc is stable. More specifically, it is determined whether or not the change amount ΔPc of the pump module pressure Pc from the previous processing cycle to the current processing cycle is smaller than a predetermined determination value (step 178).
[0095]
As a result of the above determination, if it is determined that Pc is not yet stable, then the elapsed time from the start of this routine, that is, the elapsed time counted by the timer is less than the predetermined value. It is determined whether or not it is short (step 180).
[0096]
As a result, when it is determined that the elapsed time is still shorter than the predetermined value, the processing after step 170 is repeated again. On the other hand, if it is determined that the elapsed time is already greater than or equal to the predetermined value, it is determined that an inappropriate situation has occurred in proceeding with normal processing, and the KEY OFF monitor operation flag is turned OFF ( Step 182).
[0097]
If the system is in a normal state, the pump module pressure Pc is stabilized at the φ0.5 hole judgment value before the elapsed time reaches a predetermined value. In this case, the condition of step 178 is satisfied when Pc becomes stable. In the routine shown in FIG. 8, when the condition of step 178 is established, the pump module pressure Pc at that time is stored as a φ0.5 hole determination value (step 174).
[0098]
When the ECU 60 completes the “φ0.5REF hole check process” according to the routine shown in FIG. 8, the ECU 60 subsequently executes the routine shown in FIG. FIG. 9 is a flowchart of a routine that the ECU 60 executes to detect an open failure of the block valve 28.
[0099]
In the routine shown in FIG. 9, first, the state shown at time t 5 in FIG. 2 is formed, that is, the canister 26 is cut off from the fuel tank 10, and only the internal pressure of the canister 26 is reduced by the pump 74. Therefore, each element of the evaporated fuel processing apparatus is controlled as follows (step 190).
・ Switching valve 80: ON
・ Pump 74: ON
・ Blockade valve 28: OFF (closed)
・ Purge VSV36: OFF
[0100]
In step 190, specifically, after the “φ0.5REF hole check process” is completed, the process of turning the blocking valve 28 from ON to OFF and the switching valve 80 from OFF to ON is executed. While the switching valve 80 is OFF, the pump module pressure sensor 86 is in communication with the canister 26 (atmospheric pressure) via the reference orifice 84. On the other hand, when the switching valve is turned ON, the pump module pressure sensor 86 communicates directly with the canister 26. For this reason, the pump module pressure Pc instantaneously changes to a large value at the same time as the processing of step 190 is executed (see time t5).
[0101]
When the above processing is completed, it is next determined whether or not the timer should be initialized (step 192).
When step 192 is executed for the first time after the ECU 60 starts energization, it is determined that initialization setting should be executed. In this case, next, a process for initializing the timer is executed (step 194).
On the other hand, if the current step 192 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 196).
[0102]
In the routine shown in FIG. 9, the elapsed time from the start of this routine, that is, the elapsed time counted by the timer, is greater than a predetermined value determined as the longest execution period of the blocking valve OBD process. It is determined whether or not it is smaller (step 198).
[0103]
As a result, when it is determined that the elapsed time is smaller than the predetermined value, it is determined whether or not the pump module pressure Pc at that time is smaller than the open failure determination value of the blocking valve 28 (step 200). ).
Note that the open failure determination value of the blocking valve 28 used in this step 200 may be a predetermined value or a value set based on the φ0.5 hole determination value.
[0104]
If it is determined in step 200 that the pump module pressure Pc has not yet decreased to a value smaller than the open failure determination value, it is then determined whether or not Pc has converged to a stable value (step 202).
[0105]
As a result, if it is determined that the pump module pressure Pc has not yet converged to a stable value, that is, Pc is still in the process of decreasing, the current processing cycle is terminated as it is. In this case, the processing after step 190 is repeated thereafter.
[0106]
On the other hand, if it is determined in step 202 that the pump module pressure Pc has already converged to a stable value, the pump module pressure Pc does not drop to an appropriate value that should be reached when the closing valve 28 is closed. Can be recognized. Such a phenomenon occurs only when the blocking valve 28 is not closed or when the canister 26 has a large hole. For this reason, if it is determined in step 202 that Pc has converged to a stable value, an open failure abnormality of the blocking valve 28 and a large hole abnormality of the canister 26 are determined (step 204).
Thereafter, after the KEY OFF monitor operation flag is turned off (step 206), this routine is terminated.
[0107]
If the system is in a normal state, before the pump module pressure Pc converges to a stable value, the value Pc falls to a value smaller than the open failure determination value. In this case, the condition of step 200 is satisfied when Pc falls below the open failure determination value. In the routine shown in FIG. 9, when the condition of step 200 is satisfied, at that time, a normal determination is made regarding an open failure of the blocking valve 28 and a large hole failure of the canister 26 (step 208).
When the above process ends, the process of step 212 described later is executed, and then the routine shown in FIG. 9 ends.
[0108]
If an abnormality occurs in the pump module pressure sensor 86 or the pump 74, the pump module pressure Pc does not fall below the open failure judgment value for an unreasonably long time even if the block valve 28 is normally closed, and is stable. It may not converge to the value. Under such circumstances, it cannot be accurately determined whether or not an open failure has occurred in the blocking valve 28.
[0109]
According to the routine shown in FIG. 9, when such a situation occurs, it is determined in step 198 that the elapsed time <the predetermined value is not satisfied. If such a determination is made in step 198, then a determination is made to hold the determination regarding the open failure of the block valve 28 (step 210).
[0110]
When the determination in step 208 described above or the determination in step 210 is performed, the open failure determination of the blocking valve 28 ends. When the ECU 60 finishes the determination of the open failure in this manner, the ECU 60 stores the pump module pressure Pc at that time as the reference pressure when the block valve is closed in preparation for the determination of the close failure of the block valve 28 (step 212). The routine shown in FIG. 9 ends.
[0111]
By the way, although the evaporative fuel processing apparatus of this embodiment is carrying out the open failure determination of the sealing valve 28 by the method (negative pressure method) which makes the pump module pressure Pc negative pressure with the pump 74, the open failure of the sealing valve 28 is carried out. The determination method is not limited to this. That is, the pump 74 may be used as a pressurizing pump, and the open-failure determination of the blocking valve 28 may be performed by a method (positive pressure method) that makes the pump module pressure Pc positive. In this case, the process of step 200 is corrected to a process of determining whether “Pc is larger than the open failure determination value (Pc> open fixation determination value is satisfied)”. A desired determination function can be realized.
[0112]
The ECU 60 executes the routine shown in FIG. 10 following the routine shown in FIG. FIG. 10 is a flowchart of a routine executed by the ECU 60 in order to detect a closed failure of the block valve 28.
[0113]
In the routine shown in FIG. 10, first, each element of the fuel vapor processing apparatus is controlled as follows in order to form the state shown at time t6 in FIG. 2 (step 220).
・ Switching valve 80: ON
・ Pump 74: ON
・ Blockade valve 28: ON (open)
・ Purge VSV36: OFF
Specifically, after the determination of the open failure of the blocking valve 28 is completed, a process of turning the blocking valve 28 from OFF to ON is executed.
[0114]
When the above process is completed, it is next determined whether or not the timer should be initialized (step 222).
When this step 222 is executed for the first time after the start of energization of the ECU 60, it is determined that the initialization setting should be executed. In this case, next, a process for initializing the timer is executed (step 224).
On the other hand, if the present step 222 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 226).
[0115]
In the routine shown in FIG. 10, it is next determined whether or not the absolute value of the difference between the current pump module pressure Pc and the block valve closing reference pressure stored in step 212 is equal to or greater than a predetermined value. More specifically, it is determined whether or not the pump module pressure Pc has changed significantly by turning on (opening) the sealing valve 28 by the process of step 220 (step 228).
[0116]
When the open failure determination of the blocking valve 28 is completed (time t6), the tank internal pressure Pt is almost atmospheric pressure. On the other hand, at that time, the internal pressure of the canister 26, that is, the peripheral pressure of the pump module pressure sensor 86 is sufficiently negative. Therefore, if the blocking valve 28 is normally opened by the process of step 220, then the gas in the fuel tank 10 flows into the canister 26, and the pump module pressure Pc changes greatly.
[0117]
In the routine shown in FIG. 10, if it is determined that the condition of step 228 is not satisfied (no significant change is recognized in Pc), then the elapsed time from the start of this routine, that is, It is determined whether the elapsed time counted by the timer is equal to or greater than a predetermined value (step 230).
[0118]
As a result, when it is determined that the elapsed time is shorter than the predetermined value, it is determined that there is a possibility that the valve opening pressure of the block valve 28 is not yet reflected in the pump module pressure Pc, and the steps after step 220 are performed again. Processing is executed.
[0119]
On the other hand, when it is determined that the elapsed time is already greater than or equal to the predetermined value, it can be determined that the blocking valve 28 is not normally opened. In this case, after it is determined that the closure valve 28 is closed and stuck abnormally (step 232), the KEY OFF monitor operation flag is turned OFF (step 234), and then the routine shown in FIG. 10 is terminated.
[0120]
If the system is in a normal state, a significant change occurs in the pump module pressure Pc before the elapsed time reaches a predetermined value. In this case, the condition of step 228 is satisfied when such a change occurs in Pc. In the routine shown in FIG. 10, when the condition of the above step 228 is satisfied, at that time, a normal determination is made regarding the closing failure of the block valve 28 (step 236).
[0121]
By the way, the above description is based on the premise that the open-failure determination of the blocking valve 28 is executed by the negative pressure method, but the open-failure determination of the blocking valve 28 may be executed by the positive pressure method. When the positive pressure method is used, the pump module pressure Pc is positive at the end of the open failure determination. Therefore, when the blocking valve 28 is opened at time t6, a change in the decreasing direction thereafter occurs in Pc. In step 228 shown in FIG. 10, since the change in Pc is captured as an absolute value, it can be determined whether there is a significant change regardless of the change direction of Pc. For this reason, even when the open failure determination of the blocking valve 28 is performed by the positive pressure method, the closing failure of the blocking valve 28 can be accurately determined by following the routine shown in FIG.
[0122]
When the ECU 60 completes the “blocking valve OBD process” in accordance with the routines shown in FIGS. 9 and 10, the ECU 60 subsequently executes the routine shown in FIG. FIG. 11 is a flowchart of a routine that the ECU 60 executes in order to implement the “φ0.5 leak check process”.
[0123]
In the routine shown in FIG. 11, first, in order to form the state shown at time t6 in FIG. 2, each element of the evaporated fuel processing apparatus is controlled as follows (step 240).
・ Switching valve 80: ON
・ Pump 74: ON
・ Blockade valve 28: ON (open)
・ Purge VSV36: OFF
This state is the same as the state formed in step 220 shown in FIG. Therefore, in step 240, the state of each element is not changed at all.
[0124]
When the above process ends, it is next determined whether or not the timer should be initialized (step 242).
When this step 242 is executed for the first time after the start of energization of the ECU 60, it is determined that the initialization setting should be executed. In this case, next, processing for initializing the timer is executed (step 244).
On the other hand, if the present step 242 has already been executed before the current processing cycle after the energization of the ECU 60 is started, it is determined that the initialization setting is not necessary. In this case, the timer is then counted up (step 246).
[0125]
In the routine shown in FIG. 11, next, the elapsed time from the start of this routine, that is, the elapsed time counted by the timer, is determined as the longest execution period of φ0.5 leak check processing. It is determined whether or not the value is smaller (step 248).
[0126]
As a result, if it is determined that the elapsed time is smaller than the predetermined value, it is determined whether or not the pump module pressure Pc at that time is smaller than the φ0.5 hole determination value stored in step 184 above. (Step 250).
[0127]
If it is determined in step 250 that the pump module pressure Pc has not yet decreased to a value smaller than the φ0.5 hole determination value, it is next determined whether or not Pc has converged to a stable value. (Step 252).
[0128]
As a result, if it is determined that the pump module pressure Pc has not yet converged to a stable value, that is, Pc is still in the process of decreasing, the current processing cycle is terminated as it is. In this case, the processing after step 240 is repeated thereafter.
[0129]
On the other hand, if it is determined in step 252 that the pump module pressure Pc has already converged to a stable value, it can be recognized that the pump module pressure Pc does not drop to an appropriate value to be reached. Such a phenomenon occurs only when leakage exceeding φ0.5 mm occurs in the system including the canister 26 and the fuel tank 10 or when the purge VSV 36 is not properly closed. Therefore, if it is determined in step 252 that Pc has converged to a stable value, leakage abnormality (leak check abnormality) and purge VSV 36 open failure abnormality are determined (step 254).
Thereafter, after the KEY OFF monitor operation flag is turned off (step 256), this routine is terminated.
[0130]
If the system is in a normal state, before the pump module pressure Pc converges to a stable value, the value Pc drops to a value smaller than the φ0.5 hole determination value. In this case, the condition of step 250 is satisfied when Pc falls below the φ0.5 hole determination value. In the routine shown in FIG. 11, if the condition of step 250 is satisfied, at that time, a normal determination is made regarding a leakage failure and an open failure of the purge VSV 36 (step 258).
When the above processing is completed, the routine is ended after the KEY OFF monitor operation flag is turned OFF in step 256.
[0131]
If there is an abnormality in the pump module pressure sensor 86 or the pump 74, the pump module pressure Pc does not fall below the φ0.5 hole judgment value for an unreasonably long period of time even if there is no leakage in the system. The stable value may not converge. Under such circumstances, the presence or absence of leakage cannot be accurately determined.
[0132]
According to the routine shown in FIG. 11, when such a situation occurs, it is determined in the step 248 that the elapsed time <the predetermined value is not satisfied. If such a determination is made in step 248, then a determination is made to hold the determination regarding the presence or absence of leakage (step 260).
When the above processing is completed, the routine is ended after the KEY OFF monitor operation flag is turned OFF in step 256.
[0133]
In the above description, the φ0.5 leak check process is performed by the negative pressure method, but the execution method of the process is not limited to this. That is, the φ0.5 leak check process may be executed by the positive pressure method. In this case, the processing in step 250 is modified to determine whether “Pc is larger than the φ0.5 hole determination value (Pc> φ0.5 hole determination value is satisfied)”. By doing so, a desired determination function can be realized.
[0134]
As described above, in the apparatus of the present embodiment, the normal processing shown in FIG. 2 can be realized by causing the ECU 60 to execute the routines shown in FIGS. 6 to 11 described above.
[0135]
[HC blowout occurrence determination processing]
As described above with reference to FIG. 4, is there a possibility that the apparatus of the present embodiment may cause vaporized fuel to blow through in the normal process immediately after the ECU 60 is energized for abnormality detection. Judge whether or not. Hereinafter, the contents of the process executed by the ECU 60 for the determination will be described.
[0136]
FIG. 12 is a flowchart of a first example of a routine executed by the ECU 60 for the HC blow-through occurrence determination process.
In the routine shown in FIG. 12, first, it is determined whether or not a precondition for detecting abnormality of the evaporated fuel processing apparatus is satisfied (step 270).
The preconditions determined in step 270 are the same as the conditions determined in step 110 shown in FIG.
[0137]
If it is determined that the precondition is not satisfied, the KEY OFF monitor operation flag is turned OFF (step 272), and then this routine is terminated.
On the other hand, when it is determined that the precondition is satisfied, it is determined whether or not the tank internal pressure Pt exceeds a predetermined value (step 274).
[0138]
In the apparatus of the present embodiment, the vaporized fuel blow-through occurs when the vaporized fuel in the fuel tank 10 flows into the canister 26 at once when the blocking valve 28 is switched from closed to open in the normal control process. May occur. The vaporized fuel blow-through may also occur when the gas in the canister 26 is sucked out by the pump 74 after the vaporized fuel in the fuel tank 10 flows into the canister 26. Such a blow-through of the evaporated fuel is more likely to occur as the amount of evaporated fuel flowing into the canister 26 with the opening of the closing valve 28 increases. Then, the inflow amount of the evaporated fuel becomes larger as the tank internal pressure Pt becomes higher when the blocking valve 28 is opened. Therefore, the possibility that the evaporated fuel blows through during the normal control can be estimated to some extent based on the tank internal pressure Pt immediately before the closing valve 28 is opened.
[0139]
The predetermined value used in step 274 is a predetermined value as an upper limit value of the tank internal pressure Pt that does not cause the fuel vapor to blow through during the execution of the normal process in the apparatus of this embodiment. Therefore, if it is determined in step 274 that the tank internal pressure Pt> predetermined value is established, it can be determined that there is a high possibility that the fuel vapor will blow through. In the routine shown in FIG. 12, in this case, the HC blow-through occurrence flag is set ON to indicate that there is a possibility of blow-through (step 276).
[0140]
On the other hand, if it is determined in step 274 that the tank internal pressure Pt is not greater than the predetermined value, it can be determined that there is no possibility that the fuel vapor will blow through. In this case, the HC blow-off occurrence flag is turned OFF to indicate that there is no possibility (step 278).
[0141]
When these processes are completed, the KEY OFF monitor operation flag is subsequently turned ON (step 280), and the current process cycle is terminated.
[0142]
According to the processing described above, more specifically, based on the amount of evaporated fuel that is expected to flow into the canister 26 with the execution of the normal control before the normal control is started, more specifically, Based on the tank internal pressure Pt, it can be determined whether or not an HC blow-off occurrence state is formed, and the HC blow-off occurrence flag can be appropriately processed according to the determination.
[0143]
In the routine shown in FIG. 12, the tank internal pressure Pt is regarded as a characteristic value of the inflow amount of the evaporated fuel amount, and the possibility of blow-through is determined based on the tank internal pressure Pt. However, the characteristic value of the inflow amount of the evaporated fuel is not limited to the tank internal pressure Pt. For example, the volume of the gas in the tank, that is, the space volume of the fuel tank 10 can be used as the characteristic value. Therefore, instead of the tank internal pressure Pt or together with the tank Pt, the possibility of blow-through may be determined based on the space volume of the fuel tank 10. The space volume of the fuel tank 10 can be calculated based on the output of the liquid level sensor 14.
[0144]
FIG. 13 is a flowchart of a second example of a routine that the ECU 60 executes for the HC blow-through occurrence determination process. In FIG. 13, steps that are the same as the steps shown in FIG. 12 are given the same reference numerals, and descriptions thereof are omitted or simplified.
[0145]
The routine shown in FIG. 13 is the same as the routine shown in FIG. 12 except that the processing of step 290 is executed instead of the processing of step 274 when the condition of step 270 is satisfied. That is, in the routine shown in FIG. 13, when the precondition for the abnormality detection is satisfied, it is determined whether or not the previous trip integrated purge amount is smaller than a predetermined value (step 290).
[0146]
The pre-trip integrated purge amount is an integrated amount of the purge flow that has flowed out of the canister 26 while the IG switch was turned on before the vehicle shifted to the current parking state (during the previous trip). When executing the routine shown in FIG. 13, the ECU 60 calculates the integrated value of the purge flow rate generated while the vehicle is running as a precondition. Then, after the IG switch is turned OFF, the latest accumulated purge amount record is kept. In this step 290, it is determined whether or not the accumulated purge amount during the previous trip stored in this way is smaller than a predetermined value.
[0147]
In the apparatus according to the present embodiment, the fuel vapor blow-through occurs as described above when the blocking valve 28 is switched from the closed state to the open state and when the gas in the canister 26 is subsequently sucked out by the pump 74. there is a possibility. Such a blow-by of evaporated fuel is more likely to occur as the amount of evaporated fuel adsorbed to the canister 26 increases at the start of normal control. The canister adsorption amount of the evaporated fuel becomes larger as the evaporated fuel purged during the previous trip is smaller, that is, as the previous trip integrated purge amount is smaller. Therefore, the possibility that the evaporated fuel blows through during the execution of the normal control can be estimated to some extent based on the previous trip integrated purge amount.
[0148]
The predetermined value used in step 290 is a value determined in advance as the minimum integrated purge amount necessary to prevent the vaporized fuel from blowing through during the execution of the normal process. Therefore, if it is determined in step 290 that the previous trip integrated purge amount <predetermined value is satisfied, it can be determined that there is a high possibility that the fuel vapor will blow through. In the routine shown in FIG. 13, in this case, the HC blow-off occurrence flag is turned ON in step 276 to indicate that there is a possibility of blow-through.
[0149]
On the other hand, if it is determined in step 290 that the previous trip integrated purge amount is not less than the predetermined value, it can be determined that there is no possibility that the vaporized fuel will blow through. In this case, the HC blow-off occurrence flag is turned OFF in step 278 to indicate that there is no possibility.
[0150]
According to the processing described above, immediately before the normal control is started, based on the adsorption state of the evaporated fuel in the canister 26, more specifically, based on the integrated value of the purge flow rate generated during the previous trip. In addition, it is possible to determine the possibility that the vaporized fuel will blow through during the execution of the normal control, and to appropriately process the HC blow-through occurrence flag according to the determination.
[0151]
FIG. 14 is a flowchart of a third example of a routine that the ECU 60 executes for the HC blow-through occurrence determination process. In FIG. 14, the same steps as those shown in FIG. 12 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0152]
The routine shown in FIG. 14 is the same as the routine shown in FIG. 12 except that the processing of step 300 is executed instead of the processing of step 274 when the condition of step 270 is satisfied. That is, in the routine shown in FIG. 14, when a precondition for executing abnormality detection is satisfied, it is determined whether or not the integrated purge amount after refueling is smaller than a predetermined value (step 300).
[0153]
In the present embodiment, as described above, the canister 26 is used so as to adsorb only the evaporated fuel that flows out during refueling. Therefore, the evaporated fuel adsorption state of the canister 26 is determined by how much purge is performed after refueling. When the ECU 60 executes the routine shown in FIG. 14, as a premise, the ECU 60 calculates the integrated value of the purge flow rate generated after the last refueling by a known method regardless of the ON / OFF of the IG switch, store. In step 300, it is determined whether the accumulated purge amount after refueling stored in this way is less than a predetermined value.
[0154]
In the apparatus according to the present embodiment, the blow-through of the evaporated fuel is more likely to occur as the amount of evaporated fuel adsorbed to the canister 26 increases at the start of the normal control. The canister adsorption amount of the evaporated fuel increases as the integrated purge amount after refueling decreases. Therefore, the possibility that the evaporated fuel blows through during the execution of the normal control can be estimated to some extent based on the integrated purge amount after the refueling.
[0155]
The predetermined value used in step 300 is a value that is determined in advance as a minimum integrated purge amount that is necessary to prevent the vaporized fuel from blowing through during the execution of the normal process. Therefore, if it is determined in step 300 that the accumulated purge amount after refueling <predetermined value is satisfied, it can be determined that there is a high possibility that the evaporated fuel will blow through. In the routine shown in FIG. 14, in this case, the HC blow-off occurrence flag is turned ON in step 276 to indicate that there is a possibility of blow-through.
[0156]
On the other hand, if it is determined in step 300 that the accumulated purge amount after refueling is not less than the predetermined value, it can be determined that there is no possibility that the evaporated fuel will blow through. In this case, the HC blow-off occurrence flag is turned OFF in step 278 to indicate that there is no possibility.
[0157]
According to the processing described above, just before the normal control is started, the normal control is performed based on the adsorption state of the evaporated fuel in the canister 26, more specifically, based on the accumulated purge amount after refueling. It is possible to determine the possibility of vaporized fuel blowout during execution, and to appropriately handle the HC blowout occurrence flag according to the determination.
[0158]
In the routine shown in FIG. 14, the accumulated purge amount after refueling is regarded as the characteristic value of the fuel adsorption state of the canister 26, and the possibility of blow-through is determined based on the accumulated purge amount. However, the characteristic value of the fuel adsorption state of the canister 26 is not limited to the integrated purge amount after refueling. For example, the amount of evaporated fuel adsorbed to the canister 26 during refueling (hereinafter referred to as “adsorption amount during refueling”). ) Can also be used as the characteristic value. Therefore, instead of the integrated purge amount after refueling or together with the integrated purge amount after refueling, the possibility of blow-through may be determined based on the suction amount during refueling.
[0159]
The amount of adsorption at the time of refueling is (1) the amount of evaporated fuel that has flowed out of the fuel tank 10 during refueling, that is, the amount of fuel that has been refueled, and (2) the fuel temperature at the time of refueling (the temperature of the remaining fuel, And (3) the flow velocity of the gas flowing into the canister 26, and the like. Therefore, the adsorption amount of the evaporated fuel may be calculated based on those factors. At this time, the fuel supply amount ((1) above) can be detected based on the output change of the liquid level sensor 14 before and after the fuel supply. Further, the fuel temperature (above (2)) can be measured by providing a temperature sensor in the fuel tank 10. Furthermore, the gas flow rate ((3) above) can be detected based on the output change speed of the liquid level sensor 14 during refueling.
[0160]
The evaporative fuel processing apparatus of this embodiment performs the HC blow-by by executing one of several methods described with reference to FIGS. 12 to 14 alone or by combining these methods. The occurrence flag can be processed. In this case, when executing these methods in combination, the ECU 60 is caused to execute the determinations corresponding to the individual methods separately and independently, and the determinations are collectively executed as shown below. It is good.

[0161]
As described above, the apparatus according to the present embodiment may cause vaporized fuel to blow through during the execution of the normal control prior to the execution of the normal control when the execution of the abnormality detection is requested while the vehicle is parked. It is possible to appropriately determine whether or not. And normal control is performed only when there is no such possibility, and when there is the possibility, abnormality detection itself can be stopped. For this reason, according to the apparatus of the present embodiment, it is possible to effectively prevent the evaporated fuel from blowing through the canister 26 as the abnormality is detected.
[0162]
By the way, in Embodiment 1 mentioned above, it is premised on performing abnormality detection of an evaporative fuel processing apparatus by a negative pressure method. When the abnormality detection is performed by the negative pressure method, the vaporized fuel blow-through occurs as described above in the scene where the blocking valve 28 is switched from the closed state to the open state and the scene where the gas in the canister 26 is sucked out by the pump 74. obtain. For this reason, in this embodiment, the predetermined value used in the above steps 274, 290 and 300 is set to a value that does not cause the fuel vapor to blow through in any of these two scenes.
[0163]
On the other hand, in the apparatus of this embodiment, it is possible to use the positive pressure method instead of the negative pressure method as an abnormality detection method. When the abnormality detection is performed by the positive pressure method, the scene where the vaporized fuel blows out is limited to the time when the blocking valve 28 is opened. For this reason, when the positive pressure method is used as an abnormality detection method, the predetermined values used in the above steps 274, 290 and 300 are set to values that do not cause the fuel vapor to blow through when the blocking valve 28 is opened. That's fine.
[0164]
In the first embodiment described above, the negative pressure pump module 52 adds the “differential pressure forming means” in the first invention to the process of turning on the blocking valve 28 by the process of step 130 described above. In the invention, the φ0.5 leak check process corresponds to “the differential pressure forming process” and the “leak inspection process” in the first invention, respectively. Then, the ECU 60 executes the routines shown in FIGS. 6 to 11 so that the “normal processing execution means” in the first invention executes at least one of the routines shown in FIGS. 12 to 13. As a result, the “blow-through possibility determination means” in the first invention realizes the “normal processing prohibition means” in the first invention by executing the processing of steps 112 and 116, respectively.
[0165]
Further, in the above-described first embodiment, by causing the ECU 60 to determine whether or not the evaporated fuel may be blown through the opening of the closing valve 28 by the routine shown in FIGS. The “valid opening possibility determination means” in the second aspect of the invention can be realized.
[0166]
Further, in the first embodiment described above, the ECU 60 is configured so as to determine whether or not there is a possibility that the vaporized fuel will blow through when the gas in the canister 26 is sucked out by the pump 74. By executing the routine shown in FIG. 14, the “negative pressure forming blow-through possibility determining means” in the third aspect of the present invention is realized.
[0167]
Further, in the first embodiment described above, the “leak detection stopping means” in the fourth aspect of the present invention is realized by the ECU 60 executing the processing of steps 112 and 116 described above.
[0168]
Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.
As in the case of the first embodiment, the fuel vapor processing apparatus of the present embodiment can be realized by the configuration shown in FIG. Further, in the present embodiment, the ECU 60 executes the ECU energization determination routine shown in FIG. 3 and the ECU power cut-off determination routine shown in FIG. 5 as in the case of the first embodiment. At least one of the HC blow-through occurrence determination routines shown is executed. The apparatus according to the present embodiment can be realized by causing the ECU 60 to execute the routines shown in FIGS. 15 to 20 described later together with these routines.
[0169]
In the case of the above-described apparatus of the first embodiment, when there is a possibility that the evaporated fuel may blow through with the execution of the normal control, the abnormality detection itself is stopped to prevent the blow-through. By the way, such a blow-by of the evaporated fuel occurs when the blocking valve 28 is opened during the execution of the normal control. Therefore, even if it is determined that there is a possibility of blow-through, it is possible to prevent the vaporized fuel from blowing through unless the blocking valve 28 is opened. Therefore, in the present embodiment, when it is determined that there is a possibility that the evaporated fuel may blow through with the execution of the normal control, abnormality detection is performed only on the canister 26 side with the blocking valve 28 closed. Hereinafter, the processing for detecting the abnormality is referred to as “canister leak detection processing”.
[0170]
[Description of canister leak detection processing]
Hereinafter, with reference to FIG. 15, the contents of the canister leak detection process executed when it is determined that there is a possibility that the fuel vapor will blow through after the energization of the ECU 60 is started will be described.
[0171]
When a predetermined time (for example, 5 hours) is counted by the built-in soak timer, the ECU 60 is started as shown in FIG. 15 to start the abnormality detection process (time T1). The blocking valve 28 is closed in principle while the vehicle is parked. For this reason, as indicated by a broken line in FIG. 15E, the tank internal pressure Pt is normally a positive pressure or a negative pressure when the ECU 60 is activated.
[0172]
After the time T1, it is determined in the ECU 60 whether or not there is a possibility that the fuel vapor will blow through with the execution of the normal control. As a result, if it is determined that there is a possibility of blow-through, “atmospheric pressure determination processing” is started with the blockade valve 28 closed (time T2). At the time T2, the switching valve 80 is in the OFF state, so that atmospheric pressure is introduced around the pump module pressure sensor 86. Therefore, the ECU 60 confirms that the pump module pressure Pc is stable after time T2, and recognizes Pc at that time as an atmospheric pressure equivalent value. Thereafter, the ECU 60 executes calibration processing of the pump module pressure sensor 86 based on the Pc (atmospheric pressure equivalent value).
[0173]
The canister leak detection process is performed in a state where the blocking valve 28 remains closed. That is, the canister leak detection process is executed in order to detect leakage of the canister 26 under the situation where the evaporated fuel does not flow out from the fuel tank 10 to the canister 26. In this case, no matter how the evaporated fuel is generated in the fuel tank 10, the accuracy of leak detection is not affected. Therefore, in the canister leak detection process, the “evaporation amount determination process” (see FIG. 2) executed in normal control is omitted, and after the atmospheric pressure determination process, the “φ0.5REF hole check process” is started immediately. (Time T3).
[0174]
As shown in FIG. 15C, at time T3, the pump 74 is activated. Since the switching valve 80 is OFF at this time, the suction port of the pump 74 communicates with the atmosphere via the check valve 76 and the reference orifice 84. Therefore, when the pump 74 is turned on, the output of the pump module pressure sensor 86 is the same value (negative pressure) as the pump 74 is operating under the condition that the pipe has a 0.5 mm reference hole. Value).
[0175]
The ECU 60 waits for the pump module pressure Pc to converge to an appropriate value after time T3, and stores the convergence value as a φ0.5 hole determination value. Thereafter, the φ0.5 hole determination value is used as a determination value for determining whether or not the canister 26 has leaked beyond the 0.5 mm reference hole.
[0176]
In the normal processing, “blocking valve OBD processing” involving opening / closing of the blocking valve 28 is executed after “φ0.5REF hole check processing”. Since the canister leak detection process needs to proceed while the blockade valve 28 is closed, the blockade valve OBD process cannot be executed during the process. Therefore, in the canister leak detection process, after the “φ0.5REF hole check process” is completed, the execution of the “blocking valve OBD process” is omitted, and the “φ0.5 hole leak check process” is immediately started (time) T4).
[0177]
The ECU 60 turns on the switching valve 80 at time T4. When the switching valve 80 is turned on, the atmospheric hole of the canister 26 is cut off from the atmosphere, and the gas in the canister 26 starts to be sucked by the pump 74. When there is no leakage in the canister 26, the pump module pressure Pc converges to a value smaller than the φ0.5 hole determination value. On the other hand, if leakage occurs in the canister 26, Pc does not decrease to the φ0.5 hole determination value.
[0178]
Therefore, the ECU 60 can determine that there is no leakage in the canister 26 if Pc becomes a value smaller than the φ0.5 hole determination value before an appropriate time elapses after time T4. If the condition is not satisfied, it can be determined that the canister 26 has leaked beyond the reference hole.
[0179]
When the φ0.5 hole leak check process is completed, the pump 74 is turned off at that time (time T5), and after a suitable time has elapsed, the “purge VSVOBD process” is started (time T6). The ECU 60 issues a valve opening command to the purge VSV 36 at time T6. When the purge VSV 36 is properly opened by this process, the seal of the canister 26 is broken and the pump module pressure Pc starts to rise. On the other hand, if the purge VSV 36 does not open properly, no significant change occurs in Pc. When sufficient change is recognized in the pump module pressure Pc after time T6, the ECU 60 determines that the purge VSV 36 has properly changed from the closed state to the open state, while no change is recognized in Pc. Determines that the purge VSV 36 is not properly opened, that is, the purge VSV 36 has a closed failure.
[0180]
When the purge VSVOBD process ends, the canister leak detection process ends (time T7). At this time, the ECU 60 turns off all the mechanisms. As a result, the evaporated fuel processing device returns to the normal state during parking of the vehicle, that is, the state at time T1. Thereafter, when an appropriate time elapses, the ECU 60 is stopped (time T8).
[0181]
As described above, according to the evaporated fuel processing apparatus of the present embodiment, the process according to the time chart shown in FIG. 15, that is, the canister leak detection process, is performed, and the evaporated fuel is kept closed. It is possible to determine whether or not there is a leak in the system including the canister 26 without causing the air to blow into the atmosphere.
[0182]
[Description of specific processing executed by ECU]
Hereinafter, the content of the specific process which ECU60 performs in this embodiment is demonstrated.
The ECU 60 repeatedly executes the ECU energization determination routine shown in FIG. 3 in the same manner as in the first embodiment while the vehicle is parked. As a result, when a predetermined value is counted by the soak timer, energization for starting the ECU 60 in earnest is started.
[0183]
In addition, after energization is started as described above, the ECU 60 repeatedly executes the ECU power interruption judgment routine shown in FIG. 5 as in the case of the first embodiment. Then, when the KEY OFF monitor operation flag is turned OFF, the power supply is cut off at that time and a transition is made to the standby state.
[0184]
FIG. 16 is a flowchart of a precondition determination routine executed by the ECU 60 in order to process the KET OFF monitor operation flag in accordance with whether or not a precondition regarding the execution of abnormality detection is satisfied in the present embodiment. The routine shown in FIG. 16 is the same as the routine shown in FIG. 4 executed in the first embodiment, except that step 112 is omitted.
[0185]
According to the routine shown in FIG. 16, in step 110, it is determined whether or not predetermined preconditions (conditions relating to the previous trip travel history, intake air temperature and cooling water temperature, battery voltage, IG switch, etc.) are satisfied. As a result, when it is determined that the precondition is satisfied, in step 114, the KEY OFF monitor operation flag is turned ON. On the other hand, if it is determined that the precondition is not satisfied, in step 116, the KET OFF operation flag is turned OFF.
[0186]
If the KEY OFF monitor operation flag is turned OFF by the processing of the above routine, the ECU 60 is then de-energized, so that abnormality detection is prohibited. On the other hand, as long as the KEY OFF monitor operation flag is turned ON by the processing of the above routine, the energization of the ECU 60 is maintained, and thereafter, the processing described below is sequentially executed in order to advance abnormality detection.
[0187]
FIG. 17 is a flowchart of a control routine executed by the ECU 60 to realize the “atmospheric pressure determination process”. The routine shown in FIG. 17 is the same as the routine shown in FIG. 6 executed in the first embodiment except that steps 310 and 312 are added and step 140 is replaced with step 314. . In FIG. 17, the same steps as those shown in FIG. 6 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0188]
In the routine shown in FIG. 17, first, it is determined whether or not an HC blow-off occurrence state is formed (step 310).
As in the case of the first embodiment, the ECU 60 immediately determines whether or not there is a possibility that the vaporized fuel will blow through in accordance with the execution of the normal process after the energization is started. The HC blow-through occurrence flag is set to ON or OFF (see FIGS. 12 to 14). In step 310, it is determined whether or not an HC blow-off occurrence state is formed based on the state of the HC blow-off occurrence flag processed in this way.
[0189]
As a result of the above determination, when it is determined that the HC blow-through occurrence state is not formed, the processing after step 130 is executed as in the case of the first embodiment. In this case, the “atmospheric pressure determination process” is performed in the same procedure as described with reference to FIG.
[0190]
On the other hand, if it is determined in step 310 that the HC blow-off occurrence state has been formed, the atmospheric pressure determination process is performed to form the state shown at time T2 in FIG. 15, that is, with the blocking valve 28 closed. For execution, each element of the fuel vapor processing apparatus is controlled as follows (step 312).
・ Switching valve 80: OFF
・ Pump 74: OFF
・ Blockade valve 28: OFF (closed)
・ Purge VSV36: OFF
Note that the state to be realized in this step 312 is realized before the time T2. Therefore, in step 312, specifically, the state of each element is not changed at all.
[0191]
According to the state realized by step 312, atmospheric pressure is guided around the pump module pressure sensor 12. Thereafter, the ECU 60 confirms that the pump module pressure Pc is stable, and stores the value Pc as an atmospheric pressure equivalent value (steps 138 and 144).
[0192]
In the present embodiment, priority is given to simplification of the procedure, and step 144 is not distinguished between normal control and canister leak detection processing. Therefore, at step 144, the atmospheric pressure equivalent value of the tank internal pressure Pt is also stored in the canister leak detection process. In the case of the canister leak detection process, the inside of the fuel tank 10 is not opened to the atmospheric pressure, and therefore, the tank internal pressure Pt is not equal to the atmospheric pressure when step 144 is executed. However, in the case of the canister leak detection process, the tank internal pressure Pt is not used for any process, and therefore no adverse effect is caused by the above mismatch.
[0193]
In the routine shown in FIG. 17, when it is determined in step 138 that either the pump module pressure Pc or the tank internal pressure Pt is not stable, the elapsed time from the start of this routine is It is determined whether or not it is shorter than a predetermined value A or B (step 314).
[0194]
More specifically, when the current process is executed as part of the normal process, it is determined in step 314 whether or not the elapsed time <the predetermined value A is satisfied. The predetermined value A used here is the same value as the predetermined value used in step 140 shown in FIG. On the other hand, if the current process is performed as part of the canister leak detection process, it is determined in step 314 whether or not the elapsed time <the predetermined value B is satisfied. The predetermined value B is smaller than the predetermined value A.
[0195]
In the case of normal processing, since the blocking valve 28 is opened at the start of the atmospheric pressure determination processing (see time t2 in FIG. 2), a certain amount of time is required until the tank internal pressure Pt converges. On the other hand, in the canister leak detection process, there is no change that changes the pump module pressure Pc and the tank internal pressure Pt at the start of the atmospheric pressure determination process. Therefore, by distinguishing the predetermined values A and B between the normal control and the canister leak detection process, it is possible to prevent useless waiting time from occurring in the latter case.
[0196]
In the routine shown in FIG. 17, when the process of step 144 is finished, the “atmospheric pressure determination process” is finished. Thereafter, the ECU 60 starts the routine shown in FIG.
FIG. 18 is a flowchart of a routine that the ECU 60 executes to realize the “evaporation amount determination process”. The routine shown in FIG. 18 is the same as the routine shown in FIG. 7 executed in the first embodiment except that step 320 is added. In FIG. 18, the same steps as those shown in FIG. 7 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0197]
In the routine shown in FIG. 18, first, it is determined whether or not an HC blow-off occurrence state is formed (step 320).
[0198]
As a result, when it is determined that the HC blow-through occurrence state is not formed, the processing after step 150 is executed as in the case of the first embodiment. In this case, the “evaporation amount determination process” is performed in the same procedure as described with reference to FIG.
[0199]
On the other hand, when it is determined in step 320 that the HC blow-through occurrence state is formed, it is determined that it is not necessary to execute the evaporation amount determination process. In this case, thereafter, the routine shown in FIG. 18 is jumped, and the routine shown in FIG. 19 is immediately started.
[0200]
FIG. 19 is a flowchart of a control routine executed by the ECU 60 to realize the “φ0.5REF hole check process”. The routine shown in FIG. 19 is the same as the routine shown in FIG. 8 executed in the first embodiment except that steps 330 and 332 are added and step 334 is added after step 184. It is. In FIG. 19, the same steps as those shown in FIG. 8 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0201]
In the routine shown in FIG. 19, first, it is determined whether or not an HC blow-off occurrence state is formed (step 330).
[0202]
As a result, when it is determined that the HC blow-out occurrence state is not formed, the processing after step 170 is executed as in the case of the first embodiment. In this case, the “φ0.5REF hole check process” is performed in the same procedure as described with reference to FIG.
[0203]
On the other hand, if it is determined in step 330 that the HC blow-out occurrence state has been formed, the state shown at time T3 in FIG. 15 is formed, that is, around the pump module pressure sensor 86, φ0.5 mm In order to generate a negative pressure on the assumption of the presence of the reference hole, each element of the fuel vapor processing apparatus is controlled as follows (step 332).
・ Switching valve 80: OFF
・ Pump 74: ON
・ Blockade valve 28: OFF (closed)
・ Purge VSV36: OFF
[0204]
In step 332, specifically, after the atmospheric pressure determination process is completed, a process of turning on the pump 74 is executed. According to the above processing, it is possible to generate a negative pressure on the premise that a φ0.5 mm reference hole exists around the pump module pressure sensor 74 while the blocking valve 28 is closed. For this reason, according to the routine shown in FIG. 19, the φ0.5 hole determination value can be accurately detected in the canister leak detection process as in the case of the normal process.
[0205]
In the routine shown in FIG. 19, after the detection of the φ0.5 hole determination value is completed (after the process of step 184 is completed), it is determined again whether or not an HC blow-out occurrence state is formed (step 334). .
[0206]
As a result, when it is determined that the HC blow-off occurrence state is not formed, the “blocking valve OBD process”, “φ0.5 leak check process”, and “ The “purging VSVOBD process” is sequentially performed (see FIGS. 9 to 11). On the other hand, if it is determined in step 334 that the HC blow-through occurrence state has been formed, the routine shown in FIG. 20 is then started.
[0207]
FIG. 20 is a flowchart of a control routine executed by the ECU 60 to realize the “φ0.5REF hole check process” as part of the canister leak detection process. The routine shown in FIG. 20 is the same as that in FIG. 11 executed in the first embodiment except that step 240 is replaced with step 340, step 254 is replaced with step 342, and step 258 is replaced with step 344. This is similar to the routine shown. In FIG. 20, the same steps as those shown in FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[0208]
In the routine shown in FIG. 20, first, in order to form the state shown at time T4 in FIG. 15, each element of the fuel vapor processing apparatus is controlled as follows (step 340).
・ Switching valve 80: ON
・ Pump 74: ON
・ Blockade valve 28: OFF (closed)
・ Purge VSV36: OFF
[0209]
In step 340, specifically, after the “φ0.5REF hole check process” is completed, a process of turning the switching valve 80 from OFF to ON is executed. When the switching valve 80 is turned on, the pump module pressure sensor 86 that has been in communication with the canister 26 (atmospheric pressure) via the reference orifice 84 is in a state of being in direct communication with the canister 26. For this reason, the pump module pressure Pc instantaneously changes to a large value at the same time as the processing of step 340 is executed (see time T4).
[0210]
When the system is normal, the pump module pressure Pc is decreased to a value smaller than the φ0.5 hole determination value after an appropriate time has passed. If “Pc <φ0.5 hole determination value” is satisfied during the execution of the canister leak detection process, it can be determined that the canister 26 is properly sealed. In the routine shown in FIG. 20, if it is determined in step 250 that the above condition is satisfied, then normal determination is made regarding the leakage failure of the canister 26, the opening failure of the blocking valve 28, and the opening failure of the purge VSV 36 according to the above determination. (Step 344).
[0211]
When the canister 26 leaks beyond the reference hole of φ0.5 mm, the pump module pressure Pc converges to a stable value without falling below the φ0.5 hole determination value. If such a situation is recognized during the execution of the canister leak detection process, it can be determined that the canister 26 is not properly sealed. In the routine shown in FIG. 20, when it is determined in step 252 that the stable value of the pump module pressure Pc has converged, the canister 26 leaks, the block valve 28 opens, and the purge VSV 36 opens, according to the above determination. An abnormality is determined for (step 344).
[0212]
As described above, according to the routines shown in FIG. 17 to FIG. 20, when the HC blow-off occurrence state is formed when the ECU 60 is started, the canister leak detection process is executed instead of the normal process, and the block valve 28 It is possible to determine whether or not leakage has occurred in the canister 26 with the closed. For this reason, according to the evaporative fuel processing apparatus of this embodiment, the leakage of the evaporative fuel is prevented in the same manner as in the first embodiment, and the leak detection of the canister 26 is compared with that in the first embodiment. A high execution frequency can be secured.
[0213]
In the second embodiment described above, the ECU 60 combines the routines shown in FIGS. 9 to 11 and the routines shown in FIGS. 17 to 20 and performs the same processing as the routines shown in FIGS. By executing this, the “normal processing execution means” in the first invention is realized, and by executing the processing in the above steps 310, 320, 330 and 334, “normal processing prohibiting means” in the first invention Is realized.
[0214]
In the second embodiment described above, the process in step 340 is the “second differential pressure forming process” in the fifth invention, and the processes in steps 250 and 252 are the “second process in the fifth invention”. The ECU 60 executes the routine shown in FIG. 20 so that the “canister leak detection processing execution means” in the fifth aspect of the invention executes the processing of step 334. Thus, the “process switching means” according to the fifth aspect of the present invention is realized.
[0215]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
According to the first aspect of the present invention, before starting normal processing for inspecting leakage of the entire system including both the canister and the fuel tank, the evaporated fuel can be blown out from the atmospheric holes of the canister in the course of the normal processing. It can be determined whether or not there is sex. And when it is judged that there is the possibility, execution of normal processing can be prohibited. For this reason, according to the present invention, in the evaporated fuel processing apparatus including the sealing valve for sealing the fuel tank, it is possible to reliably prevent the evaporated fuel from being released into the atmosphere during the leak detection.
[0216]
According to the second aspect of the present invention, it is possible to determine whether or not there is a possibility that the evaporated fuel may blow through when the normal process is executed, particularly when the blocking valve is opened.
[0217]
According to the third aspect of the invention, when the normal process is executed, there is a possibility that the evaporated fuel may be released to the atmosphere particularly in the process of sucking the gas in the canister with the execution of the negative pressure forming process. It can be determined whether or not.
[0218]
According to the fourth aspect of the invention, when the vaporized fuel blow-through associated with the execution of the normal process is predicted, the execution of the leak detection process in the vaporized fuel processing apparatus is stopped, thereby reliably preventing the vaporized fuel from being released into the atmosphere. be able to.
[0219]
According to the fifth aspect of the present invention, when the vaporized fuel blow-through associated with the execution of the normal process is predicted, the second leak inspection process for inspecting only the leak of the system including the canister is executed instead of the normal process. Thus, it is possible to reliably prevent the evaporated fuel from being released into the atmosphere.
[0220]
According to the sixth aspect of the present invention, it is possible to determine whether or not the evaporated fuel may be blown out from the air hole based on the gas flow rate flowing from the fuel tank toward the canister when the blocking valve is opened. . The evaporated fuel is more easily blown into the atmosphere as the gas flow rate is larger. Therefore, according to the present invention, it is possible to accurately estimate whether or not the evaporated fuel may be blown into the atmosphere.
[0221]
According to the seventh aspect of the invention, it can be determined based on the tank internal pressure whether or not there is a possibility that the evaporated fuel may blow through the air holes. The flow rate of gas flowing from the fuel tank toward the canister with the opening of the blocking valve increases as the tank internal pressure increases. Therefore, according to the present invention, it is possible to accurately estimate whether or not the evaporated fuel may be blown into the atmosphere.
[0222]
According to the eighth aspect of the invention, it can be determined based on the space volume in the fuel tank whether or not there is a possibility that evaporated fuel will blow through the air holes. The flow rate of gas flowing from the fuel tank toward the canister with the opening of the blocking valve increases as the space volume in the fuel tank at the time of opening the valve increases. Therefore, according to the present invention, it is possible to accurately estimate whether or not the evaporated fuel may be blown into the atmosphere.
[0223]
According to the ninth aspect, based on the evaporated fuel adsorption state of the canister, it is possible to determine whether or not the evaporated fuel is likely to blow through the air hole. As the amount of evaporated fuel adsorbed on the canister increases, the evaporated fuel tends to blow through the atmosphere. Therefore, according to the present invention, it is possible to accurately estimate whether or not the evaporated fuel may be blown into the atmosphere.
[0224]
According to the tenth aspect of the present invention, the evaporated fuel adsorption state of the canister can be accurately estimated based on the refueling adsorption amount adsorbed by the canister during refueling.
[0225]
According to the eleventh aspect, the evaporated fuel adsorption state of the canister can be accurately estimated based on the integrated value of the evaporated fuel purged from the canister, that is, the integrated purge amount.
[0226]
According to the twelfth aspect of the present invention, the evaporated fuel adsorption state of the canister can be estimated with extremely high accuracy based on the integrated purge amount after refueling.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the configuration of a first embodiment of the present invention.
FIG. 2 is a timing chart for explaining the contents of normal processing executed in the first embodiment.
FIG. 3 is a flowchart of an ECU energization determination routine executed in the first embodiment.
FIG. 4 is a flowchart of a routine executed to process a KEY OFF monitor operation flag in the first embodiment.
FIG. 5 is a flowchart of an ECU power interruption judgment routine executed in the first embodiment.
FIG. 6 is a flowchart of an atmospheric pressure measurement routine executed in the first embodiment.
FIG. 7 is a flowchart of an evaporation generation amount measurement routine executed in the first embodiment.
FIG. 8 is a flowchart of a REF hole reference pressure measurement routine executed in the first embodiment.
FIG. 9 is a flowchart of a blocking valve open failure determination routine executed in the first embodiment.
FIG. 10 is a flowchart of a closing valve closing failure determination routine executed in the first embodiment.
FIG. 11 is a flowchart of a leak check routine executed in the first embodiment.
FIG. 12 is a flowchart of a first example of an HC blow-by occurrence determination routine executed in the first embodiment.
FIG. 13 is a flowchart of a second example of the HC blow-by occurrence determination routine executed in the first embodiment.
FIG. 14 is a flowchart of a third example of the HC blow-by occurrence determination routine executed in the first embodiment.
FIG. 15 is a timing chart for explaining the contents of canister leak detection processing executed in Embodiment 2 of the present invention;
FIG. 16 is a flowchart of a routine that is executed to process a KEY OFF monitor operation flag in the second embodiment.
FIG. 17 is a flowchart of an atmospheric pressure measurement routine executed in the second embodiment.
FIG. 18 is a flowchart of an evaporation generation amount measurement routine executed in the second embodiment.
FIG. 19 is a flowchart of a REF hole reference pressure measurement routine executed in the second embodiment.
FIG. 20 is a flowchart of a leak check routine executed as part of canister leak detection processing in the second embodiment.
[Explanation of symbols]
10 Fuel tank
12 Tank pressure sensor
14 Liquid level sensor
24 Blocking valve unit
28 Blockade valve
26 Canister
36 Purge VSV
52 Negative pressure pump unit
60 ECU (Electronic Control Unit)
74 Pump
80 selector valve
86 Pump module pressure sensor
Pc Pump module pressure (Output of pump module pressure sensor)
Pt Tank internal pressure (tank internal pressure sensor output)

Claims (12)

An evaporative fuel processing apparatus for adsorbing and processing evaporative fuel generated in a fuel tank with a canister,
A blocking valve for controlling a conduction state between the fuel tank and the canister;
A purge control valve for controlling a conduction state of a purge passage communicating the canister and the internal combustion engine;
A differential pressure forming means provided in the atmospheric hole of the canister and generating a differential pressure inside and outside the canister;
A closing valve opening process for opening the closing valve from the closed state to the opening state when the purge control valve is closed, and a pressure difference between the inside and outside of the canister when the purge control valve is closed and the closing valve is opened. A differential pressure forming process for operating the differential pressure generating means so as to cause a leak, and a leak inspection process for inspecting a leak of a system including both the canister and the fuel tank in conjunction with the execution of the differential pressure forming process. Normal processing execution means for executing normal processing including:
Prior to the start of the normal processing, in the course of the normal processing, a blow-through possibility determination means for determining whether or not evaporative fuel may blow through the atmospheric hole of the canister,
Normal processing prohibiting means for prohibiting execution of the normal processing when it is determined that there is a possibility that the evaporated fuel may blow through in the normal processing;
An evaporative fuel processing apparatus comprising: The blow-through possibility determining means includes a valve-opening possibility determining means for determining whether or not the evaporated fuel may blow through the atmospheric hole of the canister with the execution of the closing valve opening process. The evaporative fuel processing apparatus according to claim 1. The differential pressure forming process includes a negative pressure forming process in which gas is sucked from the atmospheric hole to make the inside of the canister a negative pressure,
The blow-through possibility determination means includes a negative pressure formation blow-through possibility determination means for determining whether or not the evaporated fuel may blow through the atmospheric hole of the canister during the execution of the negative pressure formation process. The evaporative fuel processing apparatus according to claim 1 or 2, characterized in that: The evaporated fuel processing apparatus according to any one of claims 1 to 3, wherein the normal process prohibiting means includes leak detection stopping means for stopping execution of leak detection processing in the evaporated fuel processing apparatus. Execution of a second differential pressure forming process for operating the differential pressure generating means so that a differential pressure is generated inside and outside the canister while the purge control valve and the blocking valve are closed, and the second differential pressure forming process And a canister leak detection process executing means for executing a canister leak detection process including a second leak inspection process for inspecting a leak of the system including the canister,
4. The evaporative fuel processing apparatus according to claim 1, wherein the normal process prohibiting means includes a process switching means for executing the canister leak detection process instead of the normal process. The blow-through possibility determination means determines whether or not the evaporated fuel may blow through the atmospheric hole based on the gas flow rate flowing out from the fuel tank toward the canister when the blocking valve is opened. 6. The evaporative fuel processing apparatus according to claim 1, wherein the evaporative fuel processing apparatus is determined. The blowout possibility determination means includes
A tank internal pressure detecting means for detecting the tank internal pressure;
7. The evaporative fuel processing apparatus according to claim 6, wherein the tank internal pressure is used as a characteristic value of a gas flow rate flowing out from the fuel tank toward the canister when the blocking valve is opened. The blowout possibility determination means includes
A spatial volume detection means for detecting the spatial volume in the fuel tank;
The evaporative fuel processing apparatus according to claim 6 or 7, wherein the space volume is used as a characteristic value of a gas flow rate flowing out from the fuel tank toward the canister when the blocking valve is opened. 9. The blow-through possibility determining means determines whether or not evaporative fuel may blow through the air hole based on the evaporated fuel adsorption state of the canister. The evaporative fuel processing apparatus according to claim 1. Oil supply control means for opening the block valve during refueling,
The blowout possibility determination means includes
A refueling adsorbed amount estimating means for estimating an evaporated fuel amount flowing into the canister from the fuel tank and adsorbed to the canister during refueling as a refueling adsorbed amount;
The evaporated fuel processing apparatus according to claim 9, wherein the adsorption amount during fueling is used as a characteristic value of the evaporated fuel adsorption state. A purge control means for opening the purge control valve and purging the evaporated fuel in the canister toward the internal combustion engine when a predetermined purge condition is satisfied;
The blowout possibility determination means includes
An integrated purge amount calculating means for calculating an integrated value of the evaporated fuel purged from the canister as an integrated purge amount;
The evaporated fuel processing apparatus according to claim 9 or 10, wherein the integrated purge amount is used as a characteristic value of the evaporated fuel adsorption state. The blowout possibility determination means includes
A post-refueling integrated purge amount calculating means for calculating an integrated purge amount after refueling;
12. The evaporated fuel processing apparatus according to claim 11, wherein the integrated purge amount after refueling is used as a characteristic value of the evaporated fuel adsorption state.

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