JP5634249B2 - Post-treatment fuel addition equipment - Google Patents

Post-treatment fuel addition equipment Download PDF

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JP5634249B2
JP5634249B2 JP2010281757A JP2010281757A JP5634249B2 JP 5634249 B2 JP5634249 B2 JP 5634249B2 JP 2010281757 A JP2010281757 A JP 2010281757A JP 2010281757 A JP2010281757 A JP 2010281757A JP 5634249 B2 JP5634249 B2 JP 5634249B2
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failure diagnosis
valve
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fuel addition
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JP2012127320A (en
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晃一 大作
晃一 大作
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UD Trucks Corp
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Description

本発明は、内燃機関の排気通路に後処理用の燃料を添加する後処理用燃料添加装置(AHI;After treatment Hydrocarbon Injector)に関し、特に、その故障診断技術に関する。   The present invention relates to an aftertreatment hydrocarbon injector (AHI) for adding an aftertreatment fuel to an exhaust passage of an internal combustion engine, and more particularly to a failure diagnosis technique thereof.

内燃機関(特にディーゼルエンジン)では、排気通路にDPF(ディーゼルパティキュレートフィルタ)を配置して、排気中のPM(粒子状物質)を捕集している。
後処理用燃料添加装置は、DPFを強制的に再生する際に、DPFの上流側に燃料を添加し、これにより排気温度を上昇させて、DPFに堆積したPMを燃焼除去するために用いられる。
In an internal combustion engine (particularly a diesel engine), a DPF (diesel particulate filter) is disposed in an exhaust passage to collect PM (particulate matter) in the exhaust.
The post-processing fuel addition device is used to add fuel to the upstream side of the DPF when the DPF is forcibly regenerated, thereby raising the exhaust gas temperature and burning and removing PM accumulated in the DPF. .

かかる後処理用燃料添加装置の故障は、後処理用燃料の排気通路への漏洩や触媒劣化を招くため、定期的に診断する必要がある。
特許文献1には、燃料添加バルブの故障診断において、燃料添加の非実行時に、当該バルブ下流側の空燃比センサ出力に基づいて、バルブの漏洩異常を診断している。
Such a failure of the aftertreatment fuel addition device causes leakage of the aftertreatment fuel into the exhaust passage and deterioration of the catalyst, and therefore needs to be regularly diagnosed.
In Patent Document 1, in the failure diagnosis of the fuel addition valve, when the fuel addition is not executed, the valve leakage abnormality is diagnosed based on the air-fuel ratio sensor output on the downstream side of the valve.

また、特許文献2では、燃料添加バルブの故障診断において、所定空燃比を燃料添加により得たときの添加量を、エンジン用燃料インジェクタのポスト噴射により得たときの噴射量と比較して、バルブの故障を診断している。   Further, in Patent Document 2, in the failure diagnosis of the fuel addition valve, the addition amount when the predetermined air-fuel ratio is obtained by fuel addition is compared with the injection amount obtained by post injection of the engine fuel injector. Diagnosing a malfunction in

特開2005−232991号公報Japanese Patent Laid-Open No. 2005-232991 特開2007−146825号公報JP 2007-146825 A

ところで、後処理用燃料添加装置の故障診断は、内燃機関の始動時に実行可能であることが望まれる。
しかし、始動時に燃料添加を実際に行ってしまうと、添加した燃料が燃焼することなく滞留してしまう。このため、始動時の故障診断を可能とするためには、燃料添加を実際に行うことなく故障診断できるようにする必要がある。
By the way, it is desired that the failure diagnosis of the post-processing fuel addition apparatus can be executed when the internal combustion engine is started.
However, if the fuel addition is actually performed at the time of starting, the added fuel stays without burning. For this reason, in order to enable failure diagnosis at start-up, it is necessary to enable failure diagnosis without actually adding fuel.

この点、特許文献1に記載の技術では、燃料添加の非実行時に、空燃比センサ出力に基づいて、バルブの漏洩異常を診断しているが、始動時には空燃比センサが活性化していないので、空燃比センサを用いて始動時に故障診断することは困難である。
特許文献2に記載の技術では、燃料添加を実際に行う必要があり、始動時の故障診断は困難である。
In this regard, in the technique described in Patent Document 1, a valve leakage abnormality is diagnosed based on the output of the air-fuel ratio sensor when fuel addition is not performed. However, since the air-fuel ratio sensor is not activated at the start, It is difficult to diagnose a failure at start-up using an air-fuel ratio sensor.
In the technique described in Patent Document 2, it is necessary to actually add fuel, and it is difficult to diagnose a failure at the start.

本発明は、このような実状に鑑み、後処理用燃料添加装置の故障診断を燃料添加を実際に行うことなく始動時から実行可能とすることを課題とする。   In view of such a situation, it is an object of the present invention to enable failure diagnosis of a post-processing fuel addition apparatus to be executed from the start without actually performing fuel addition.

本発明に係る後処理用燃料添加装置は、燃料供給源からの燃料供給通路と、空気供給源からの空気供給通路と、これら両通路を合流させた合流通路と、この合流通路の端部に接続されて前記排気通路に臨む噴射ノズルと、前記燃料供給通路の上流側に介装された燃料カットオフバルブと、前記燃料供給通路の下流側に介装された燃料添加バルブと、前記空気供給通路に介装された空気パージバルブと、これらのバルブの作動を制御する制御ユニットと、前記燃料供給通路における前記燃料カットオフバルブと前記燃料添加バルブとの間の圧力を検出する圧力センサと、を含んで構成される。   The post-treatment fuel addition apparatus according to the present invention includes a fuel supply passage from a fuel supply source, an air supply passage from an air supply source, a merge passage that joins both the passages, and an end of the merge passage. An injection nozzle connected to the exhaust passage, a fuel cut-off valve interposed upstream of the fuel supply passage, a fuel addition valve interposed downstream of the fuel supply passage, and the air supply An air purge valve interposed in the passage, a control unit for controlling the operation of these valves, and a pressure sensor for detecting a pressure between the fuel cutoff valve and the fuel addition valve in the fuel supply passage. Consists of including.

そして、前記制御ユニットは、下記(1)、(2)の故障診断モードを有する構成とする。
(1)前記燃料カットオフバルブを閉じ、前記空気パージバルブを閉じた後、前記燃料添加バルブを一時的に開いて再び閉じた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第1の故障診断モード
(2)前記燃料カットオフバルブを閉じ、前記空気パージバルブ及び前記燃料添加バルブを開いた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第2の故障診断モード
そして、前記制御ユニットは、少なくとも、エンジン始動直後に、前記第1の故障診断モード、前記第2の故障診断モードの順で、故障診断を行う。
The control unit has a failure diagnosis mode (1) or (2) below.
(1) closing the fuel cutoff valve, after closing the air purge valve, in the fuel addition state the valve was closed temporarily open again-out based on the pressure detected by the pressure sensor, the threshold First failure diagnosis mode for diagnosing the presence or absence of a failure by comparison with a value (2) Detected by the pressure sensor in a state where the fuel cutoff valve is closed and the air purge valve and the fuel addition valve are opened -out based on the pressure, in comparison with the threshold value, a second failure diagnosis mode for diagnosing the presence or absence of a fault
The control unit performs failure diagnosis in the order of the first failure diagnosis mode and the second failure diagnosis mode at least immediately after the engine is started.

更には、下記(3)の故障診断モードを有する構成とすることが望ましい。
(3)前記燃料カットオフバルブを閉じ、前記空気パージバルブを閉じ、前記燃料添加バルブを開いた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第3の故障診断モード
この場合、前記制御ユニットは、少なくとも、エンジン始動直後に、前記第1の故障診断モード、前記第2の故障診断モード、前記第3の故障診断モードの順で、故障診断を行うことが望ましい。
Furthermore, it is desirable to have a configuration having a failure diagnosis mode (3) below.
(3) closing the fuel cutoff valve, closing the air purge valve, with open said fuel addition valve,-out based on the pressure detected by the pressure sensor, in comparison with the threshold value, the fault Third failure diagnosis mode to diagnose presence / absence
In this case, it is desirable that the control unit performs the failure diagnosis in the order of the first failure diagnosis mode, the second failure diagnosis mode, and the third failure diagnosis mode at least immediately after starting the engine.

本発明によれば、燃料カットオフバルブを閉じた状態で故障診断するため、燃料添加を実行することなく、診断でき、しかも圧力センサを用いて診断するので、始動時から故障診断が可能となる。また、特に空気パージバルブを用い、空気圧力で診断することにより、正確な診断が可能となる。   According to the present invention, since the failure diagnosis is performed with the fuel cut-off valve closed, the diagnosis can be performed without executing the fuel addition, and the diagnosis can be performed using the pressure sensor. . Further, accurate diagnosis is possible by using the air purge valve and diagnosing with air pressure.

本発明の一実施形態を示す後処理用燃料添加装置のシステム図1 is a system diagram of a post-processing fuel addition apparatus showing an embodiment of the present invention. 第1〜第3の故障診断モードを説明するためのタイムチャートTime chart for explaining the first to third failure diagnosis modes 診断診断のフローチャートDiagnosis flowchart

以下、本発明の実施の形態について、詳細に説明する。
図1は本発明の一実施形態を示す後処理用燃料添加装置のシステム図である。
Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a system diagram of an aftertreatment fuel addition apparatus showing an embodiment of the present invention.

燃料供給源からの燃料供給通路1と、空気供給源からの空気供給通路2とが設けられ、これらは合流して、合流通路3をなしている。合流通路3の端部には噴射ノズル4が接続され、噴射ノズル4は図示しない内燃機関の排気通路のDPF上流側に臨んでいる。   A fuel supply passage 1 from the fuel supply source and an air supply passage 2 from the air supply source are provided. These join together to form a merge passage 3. An injection nozzle 4 is connected to the end of the merging passage 3, and the injection nozzle 4 faces the DPF upstream side of an exhaust passage (not shown) of the internal combustion engine.

燃料供給通路1には、その上流側に燃料遮断用の燃料カットオフバルブ(Fuel Cut-off Valve;以下「FCV」という)5が設けられ、下流側に添加流量制御用の燃料添加バルブ(Fuel Dosing Valve ;以下「FDV」という)6が設けられる。
空気供給通路2には、空気パージ制御用の空気パージバルブ(Air Purge Valve ;以下「APV」という)」7が設けられる。
The fuel supply passage 1 is provided with a fuel cut-off valve (Fuel Cut-off Valve; hereinafter referred to as “FCV”) 5 on the upstream side, and a fuel addition valve (Fuel for control of addition flow rate) on the downstream side. Dosing Valve (hereinafter referred to as “FDV”) 6 is provided.
The air supply passage 2 is provided with an air purge valve (Air Purge Valve; hereinafter referred to as “APV”) 7 for air purge control.

また、燃料供給通路1におけるFCV5とFDV6との間に逆流防止用のチェックバルブ8が設けられ、空気供給通路2におけるAPV7下流に逆流防止用のチェックバルブ9が設けられる。
また、燃料供給通路1におけるFCV5とFDV6との間で、チェックバルブ8の下流、従って、チェックバルブ8とFDV6との間に、当該部位の圧力を検出する圧力センサ10が設けられる。
Further, a check valve 8 for preventing backflow is provided between the FCV 5 and the FDV 6 in the fuel supply passage 1, and a check valve 9 for preventing backflow is provided downstream of the APV 7 in the air supply passage 2.
Further, a pressure sensor 10 is provided between the FCV 5 and the FDV 6 in the fuel supply passage 1, downstream of the check valve 8, and therefore between the check valve 8 and the FDV 6.

前記FCV5、FDV6及びAPV7は、いずれも電磁バルブであり、これらの作動は、制御ユニット11により制御される。この制御ユニット11には、内燃機関の運転条件やDPFの強制再生の要否の判断のために、図示しない各種のセンサからの信号が入力されると共に、前記圧力センサ10からの信号も入力されている。
尚、図1に点線Mで囲んで示すように、FCV5、FDV6、APV7、チェックバルブ8、9及び圧力センサ10は、1つのケーシング内に収容されて、モジュール化されている。
The FCV 5, FDV 6 and APV 7 are all electromagnetic valves, and their operation is controlled by the control unit 11. The control unit 11 is supplied with signals from various sensors (not shown) as well as signals from the pressure sensor 10 in order to determine the operating conditions of the internal combustion engine and the necessity of forced regeneration of the DPF. ing.
In addition, as enclosed by the dotted line M in FIG. 1, FCV5, FDV6, APV7, the check valves 8, 9 and the pressure sensor 10 are accommodated in one casing and modularized.

上記の後処理用燃料添加装置では、制御ユニット11により、DPFの強制再生の要否を判断して、強制再生時には、空気供給通路2のAPV7を閉じ、燃料供給通路1のFCV5及びFDV6を開いて、噴射ノズル4に燃料を供給し、噴射ノズル4から排気通路内に燃料を添加する。これにより、排気通路内で添加燃料を酸化させて昇温し、DPFに堆積しているPMを燃焼除去する。   In the above post-treatment fuel addition apparatus, the control unit 11 determines whether or not forced regeneration of the DPF is necessary, and during forced regeneration, the APV 7 in the air supply passage 2 is closed and the FCV 5 and FDV 6 in the fuel supply passage 1 are opened. Then, the fuel is supplied to the injection nozzle 4 and the fuel is added from the injection nozzle 4 into the exhaust passage. As a result, the added fuel is oxidized in the exhaust passage to raise the temperature, and PM accumulated in the DPF is burned and removed.

強制再生のための燃料添加の終了時は、燃料供給通路1のFCV5及びFDV6を閉じて、燃料噴射を停止させる。その後、空気供給通路2のAPV7を一時的に開いて、パージ空気を供給し、合流通路3及び噴射ノズル4に残っている燃料をパージする。これにより、合流通路3及び噴射ノズル4内の燃料が炭化して付着し、詰まり等を生じないようにする。   At the end of fuel addition for forced regeneration, FCV 5 and FDV 6 in fuel supply passage 1 are closed to stop fuel injection. Thereafter, the APV 7 in the air supply passage 2 is temporarily opened, purge air is supplied, and fuel remaining in the merge passage 3 and the injection nozzle 4 is purged. As a result, the fuel in the merging passage 3 and the injection nozzle 4 is carbonized and adhered to prevent clogging.

また、燃料添加を実行しないときは、定期的に、空気供給通路2のAPV7を開いて、合流通路3及び噴射ノズル4にパージ空気を供給する。これは、排気通路から排気が噴射ノズル4内に逆流して排気中の煤が内部に付着したり、ノズル4に煤が堆積するのを防止するためである。内燃機関の停止時(キーOFF時)も同様に煤除去のためのパージを行う。   When fuel addition is not executed, the APV 7 of the air supply passage 2 is periodically opened to supply purge air to the merging passage 3 and the injection nozzle 4. This is to prevent exhaust from flowing backward from the exhaust passage into the injection nozzle 4 and soot in the exhaust to adhere to the inside or accumulation of soot from the nozzle 4. Similarly, purging for removing soot is performed when the internal combustion engine is stopped (when the key is OFF).

次に制御ユニット11による故障診断について説明する。
制御ユニット11は、FCV5、FDV6及びAPV7の開閉を制御しつつ、圧力センサ10からの信号に基づいて、後処理用燃料添加装置の故障の有無を診断する機能を備えている。
Next, failure diagnosis by the control unit 11 will be described.
The control unit 11 has a function of diagnosing the presence or absence of a failure in the post-processing fuel addition device based on a signal from the pressure sensor 10 while controlling the opening and closing of the FCV 5, the FDV 6, and the APV 7.

図2は制御ユニット11による故障診断のタイムチャートである。
故障診断は、(1)第1の故障診断モード、(2)第2の故障診断モード、(3)第3の故障診断モードの順で実行する。
FIG. 2 is a time chart of failure diagnosis by the control unit 11.
The failure diagnosis is executed in the order of (1) first failure diagnosis mode, (2) second failure diagnosis mode, and (3) third failure diagnosis mode.

(1)第1の故障診断モード
FCV5、FDV6、APV7の閉弁状態から、FDV6を一定期間開いて、再び閉じる。これは、FDV6を開くことで、FCV5とFDV6との間の圧力を逃がし、再びFDV6を閉じることで、FCV5とFDV6との間を低圧状態に保つようにする。そして、図2中の(1)のタイミングで、圧力センサ10により検出される圧力を読込み、しきい値と比較して、低圧状態か否かを判定する。低圧状態であれば、正常であるが、高圧状態であれば、FCV5の開故障(リーク)、FDV6の開故障、APV7の開故障が考えられる。尚、ここでいう「開故障」とは、開状態のまま固着してしまったような故障をいい、「閉故障」とは、閉状態のまま固着してしまったような故障をいう。
(1) First failure diagnosis mode From the closed state of FCV5, FDV6, and APV7, FDV6 is opened for a certain period and then closed again. This opens the FDV6 to release the pressure between the FCV5 and the FDV6, and closes the FDV6 again to keep the low pressure state between the FCV5 and the FDV6. Then, at the timing of (1) in FIG. 2, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether or not it is in a low pressure state. If it is a low pressure state, it is normal, but if it is a high pressure state, an open failure (leakage) of FCV5, an open failure of FDV6, and an open failure of APV7 can be considered. Here, “open failure” refers to a failure that is stuck in an open state, and “closed failure” refers to a failure that is stuck in a closed state.

(2)第2の故障診断モード
引き続きFCV5を閉じたまま、APV7を開き、次いでFDV6を開く。これは、APV7とFDV6を開くことで、APV7からの空気をFCV5とFDV6との間に導いて、圧力センサ10部の圧力が上昇していく状況を作り出している。尚、APV7からの空気は噴射ノズル4より流出するが、噴射ノズル4は一種のオリフィスとして機能するので、圧力センサ10部の圧力は上昇する。そして、この状態、すなわち、図2中の(2)のタイミングで、圧力センサ10により検出される圧力を読込み、しきい値と比較して、高圧状態か否かを判定する。高圧状態であれば、正常であるが、低圧状態であれば、FDV6の閉故障、APV7の閉故障が考えられる。
(2) Second failure diagnosis mode With the FCV 5 closed, the APV 7 is opened, and then the FDV 6 is opened. This opens the APV 7 and the FDV 6 to lead the air from the APV 7 between the FCV 5 and the FDV 6, thereby creating a situation where the pressure of the pressure sensor 10 part increases. Note that air from the APV 7 flows out of the injection nozzle 4, but the injection nozzle 4 functions as a kind of orifice, so the pressure of the pressure sensor 10 increases. Then, in this state, that is, at the timing (2) in FIG. 2, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether or not it is in a high pressure state. If it is in a high pressure state, it is normal, but if it is in a low pressure state, a closed failure of FDV6 and a closed failure of APV7 are considered.

(3)第3の故障診断モード
引き続きFCV5を閉じたまま、先ずFDV6を閉じ、これと同時又は遅らせてAPV7を閉じ、しかる後、FDV6を開く。これは、FDV6を閉じて、圧力センサ10部を高圧状態に保持し、これと同時又は遅らせてAPV7を閉じて空気供給を停止し、その後にFDV6を開くことで、圧力センサ10部の圧力が低下していく状況を作り出している。そして、この状態、すなわち、図2中の(3)のタイミングで、圧力センサ10により検出される圧力を読込み、しきい値と比較して、低圧状態になったか否かを判定する。低圧状態であれば、正常であるが、高圧状態であれば、FCV5の開故障、FDV6の開故障、APV7の開故障が考えられる。
(3) Third Failure Diagnosis Mode With the FCV 5 still closed, the FDV 6 is first closed, the APV 7 is closed simultaneously or delayed, and then the FDV 6 is opened. This is because the FDV 6 is closed, the pressure sensor 10 part is held in a high pressure state, and simultaneously or delayed, the APV 7 is closed to stop the air supply, and then the FDV 6 is opened, whereby the pressure of the pressure sensor 10 part is reduced. It creates a declining situation. Then, in this state, that is, at the timing (3) in FIG. 2, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether or not a low pressure state has been reached. If it is in a low pressure state, it is normal, but if it is in a high pressure state, an open failure of FCV5, an open failure of FDV6, and an open failure of APV7 can be considered.

図3は制御ユニット11による上記第1〜第3の故障診断モードを用いた故障診断ルーチンのフローチャートであり、本ルーチンはエンジン始動直後に実行される。   FIG. 3 is a flowchart of a failure diagnosis routine using the first to third failure diagnosis modes by the control unit 11, and this routine is executed immediately after the engine is started.

S1では、予め定めた診断開始条件が成立しているか否かを判定する。ここでいう診断開始条件とは、例えば、燃料供給源の燃料圧力、及び、空気供給源(圧縮空気源)の空気圧力が確保されていることを条件とする。燃料を添加しないが、燃料の漏洩を見るために、エンジンと連動して作動する燃料ポンプにより燃料圧力が上昇している必要があるからである。また、パージ空気を用いるために空気圧力が確保されている必要があり、長時間エンジンを運転していないと、空気供給源(圧縮空気タンク)が空になっている恐れがあり、エンジンと連動して作動する圧縮空気ポンプ(コンプレッサ)により充填してからでないと診断を行えないからである。診断開始条件が成立した場合は、S2へ進む。   In S1, it is determined whether a predetermined diagnosis start condition is satisfied. The diagnosis start condition here is, for example, a condition that the fuel pressure of the fuel supply source and the air pressure of the air supply source (compressed air source) are secured. This is because the fuel pressure needs to be increased by a fuel pump that operates in conjunction with the engine in order to observe fuel leakage, although no fuel is added. Also, air pressure needs to be secured in order to use purge air, and if the engine has not been operated for a long time, the air supply source (compressed air tank) may be empty and linked with the engine. This is because a diagnosis cannot be made without filling with a compressed air pump (compressor) that operates as described above. If the diagnosis start condition is satisfied, the process proceeds to S2.

S2では、第1の故障診断モード(FCVリークチェック等)を実行する。すなわち、FCV5を閉じ、APV7を閉じた後、FDV6を一時的に開いて再び閉じる。そして、S3では、圧力センサ10により検出される圧力を読込み、しきい値と比較して、圧力は予測範囲内(低圧状態)か否かを判定する。
この判定で、予測範囲内(低圧状態)の場合は、S5へ進み、予測範囲外(高圧状態)の場合は、S4へ進んで、FCV5の開故障、FDV6の開故障、APV7の開故障の疑いありと記憶した後、S5へ進む。
In S2, the first failure diagnosis mode (FCV leak check or the like) is executed. That is, after FCV5 is closed and APV7 is closed, FDV6 is temporarily opened and then closed again. In S3, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether or not the pressure is within the predicted range (low pressure state).
In this determination, if it is within the prediction range (low pressure state), the process proceeds to S5. If it is outside the prediction range (high pressure state), the process proceeds to S4, and FCV5 open failure, FDV6 open failure, and APV7 open failure occur. After memorizing that there is a suspicion, proceed to S5.

S5では、第2の故障診断モード(空気圧上昇チェック等)を実行する。すなわち、FCV5を閉じたまま、APV7を開き、次いでFDV6を閉状態から一定期間開く。そして、S6では、FDV6の開期間において、圧力センサ10により検出される圧力を読込み、しきい値と比較して、圧力は予測範囲内(高圧状態)か否かを判定する。
この判定で、予測範囲内(高圧状態)の場合は、S8へ進み、予測範囲外(低圧状態)の場合は、S7へ進んで、FDV6の閉故障、APV7の閉故障の疑いありと記憶した後、S8へ進む。
In S5, the second failure diagnosis mode (air pressure rise check or the like) is executed. That is, with the FCV 5 closed, the APV 7 is opened, and then the FDV 6 is opened for a certain period from the closed state. In S6, during the open period of the FDV 6, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether the pressure is within the predicted range (high pressure state).
In this determination, if it is within the prediction range (high pressure state), the process proceeds to S8, and if it is outside the prediction range (low pressure state), the process proceeds to S7, and the FDV6 closed fault and the APV7 closed fault are suspected. Then, the process proceeds to S8.

S8では、第3の故障診断モード(空気圧下降チェック等)を実行する。すなわち、FCV5を閉じたまま、APV7を閉じ、FDV6を閉状態から一定期間開く。そして、S9では、FDV6の開期間において、圧力センサ10により検出される圧力を読込み、しきい値と比較して、圧力は予測範囲内(低圧状態)か否かを判定する。
この判定で、予測範囲内(低圧状態)の場合は、S11へ進み、予測範囲外(高圧状態)の場合は、S10へ進んで、FCV5の開故障、FDV6の開故障、APV7の開故障の疑いありと記憶した後、S11へ進む。
In S8, a third failure diagnosis mode (air pressure drop check or the like) is executed. That is, with the FCV 5 closed, the APV 7 is closed and the FDV 6 is opened for a certain period from the closed state. In S9, in the open period of the FDV 6, the pressure detected by the pressure sensor 10 is read and compared with a threshold value to determine whether or not the pressure is within the predicted range (low pressure state).
In this determination, if it is within the prediction range (low pressure state), the process proceeds to S11. If it is outside the prediction range (high pressure state), the process proceeds to S10, and FCV5 open failure, FDV6 open failure, and APV7 open failure occur. After memorizing that there is a suspicion, proceed to S11.

S11では、以上の第1〜第3の故障診断モードで、故障の疑いありであったか否かを判定し、疑いありの場合は、S12へ進む。
S12では、診断回数を予め定めたしきい値と比較する。診断回数は、S2〜S11のループを回る毎に、1アップされ、しきい値未満の場合は、S2へ戻って、S2〜S11のループを繰り返す。
In S11, it is determined whether or not there is a suspicion of failure in the first to third failure diagnosis modes described above. If there is a suspicion, the process proceeds to S12.
In S12, the number of diagnoses is compared with a predetermined threshold value. The number of times of diagnosis is incremented by 1 every time the loop of S2 to S11 is performed.

S11、S12の判定で、故障の疑いありで、かつ、診断回数がしきい値に達した場合は、S13へ進んで、故障コードをセットし、ユーザー又はサービスマン向けに適宜表示する。また同時にフェイルセーフモードに入る。フェイルセーフモードでは、全てのバルブ5、6、7に対し閉弁を指令する。
S11での判定で、故障の疑いなしの場合は、S14へ進んで、故障コードをクリアする。
If it is determined in S11 or S12 that there is a suspicion of failure and the number of diagnoses has reached a threshold value, the process proceeds to S13, where a failure code is set and displayed appropriately for the user or service person. At the same time, it enters the fail safe mode. In the fail safe mode, all the valves 5, 6, 7 are instructed to close.
If it is determined in S11 that there is no suspicion of failure, the process proceeds to S14 and the failure code is cleared.

本実施形態によれば、第1〜第3の故障診断モードのいずれにおいても、FCV5を閉じた状態で故障診断するため、燃料添加を実行することなく、診断でき、しかも圧力センサ10を用いて診断するので、エンジン始動直後から故障診断が可能となる。   According to the present embodiment, in any of the first to third failure diagnosis modes, the failure diagnosis is performed with the FCV 5 closed, so that the diagnosis can be performed without adding fuel and the pressure sensor 10 is used. Since diagnosis is performed, failure diagnosis can be performed immediately after the engine is started.

また、本実施形態によれば、FCV5を閉じ、APV7及びFDV6を更に閉じた状態で、FCV5、FDV6間の圧力センサ10により検出される圧力に基づいて、故障の有無を診断する第1の故障診断モードと、FCV5を閉じ、APV7及びFDV6を開いた状態で、前記圧力センサ10により検出される圧力に基づいて、故障の有無を診断する第2の故障診断モードと、を有することにより、FCV5,FDV6及びAPV7の各種故障を検知・診断することができる。   Further, according to the present embodiment, the first failure is diagnosed based on the pressure detected by the pressure sensor 10 between the FCV 5 and the FDV 6 with the FCV 5 closed and the APV 7 and FDV 6 further closed. By having a diagnosis mode and a second failure diagnosis mode for diagnosing the presence or absence of a failure based on the pressure detected by the pressure sensor 10 with the FCV 5 closed and the APV 7 and FDV 6 opened, the FCV 5 , FDV6 and APV7 can be detected and diagnosed.

また、本実施形態では、FCV5を閉じ、APV7を閉じ、FDV6を開いた状態で、前記圧力センサ10により検出される圧力に基づいて、故障の有無を診断する第3の故障診断モードを更に有することにより、更に多くの各種故障を検知・診断することが可能となる。   In addition, the present embodiment further includes a third failure diagnosis mode for diagnosing the presence or absence of a failure based on the pressure detected by the pressure sensor 10 with the FCV 5 closed, the APV 7 closed, and the FDV 6 opened. As a result, it becomes possible to detect and diagnose more various failures.

また、本実施形態によれば、前記第1の故障診断モード、前記第2の故障診断モード、前記第3の故障診断モードの順で、故障診断を行うことにより、一連の診断を効率的に行うことが可能となる。   In addition, according to the present embodiment, a series of diagnoses can be efficiently performed by performing failure diagnosis in the order of the first failure diagnosis mode, the second failure diagnosis mode, and the third failure diagnosis mode. Can be done.

尚、以上では、エンジン始動直後の故障診断について説明したが、これに限るものではない。すなわち、本発明による故障診断は、エンジン始動直後に極めて有効であることは言うまでもないが、エンジン始動直後のみでなく、エンジン運転中やキーOFF時に実行することもできる。もちろん、エンジン運転中は、燃料添加を実際に行いながら診断することが可能であるので、エンジン始動直後とは別に、FCV5及びFDV6を開いて燃料添加を実行しながら行う故障診断モードによって故障診断を行うようにしてもよい。   In the above description, the failure diagnosis immediately after the engine is started has been described. However, the present invention is not limited to this. That is, it goes without saying that the failure diagnosis according to the present invention is extremely effective immediately after the engine is started, but can be executed not only immediately after the engine is started but also when the engine is operating or when the key is turned off. Of course, during engine operation, it is possible to make a diagnosis while actually adding fuel. Therefore, in addition to immediately after starting the engine, failure diagnosis is performed by a failure diagnosis mode performed while opening FCV5 and FDV6 and performing fuel addition. You may make it perform.

また、図示の実施形態はあくまで本発明を例示するものであり、本発明は、説明した実施形態により直接的に示されるものに加え、特許請求の範囲内で当業者によりなされる各種の改良・変更を包含するものであることは言うまでもない。   The illustrated embodiments are merely examples of the present invention, and the present invention is not limited to those directly described by the described embodiments, and various improvements and modifications made by those skilled in the art within the scope of the claims. Needless to say, it encompasses changes.

1 燃料供給通路
2 空気供給通路
3 合流通路
4 噴射ノズル
5 燃料カットオフバルブ(FCV)
6 燃料添加バルブ(FDV)
7 空気パージバルブ(APV)
8、9 チェックバルブ
10 圧力センサ
11 制御ユニット
1 Fuel Supply Passage 2 Air Supply Passage 3 Merge Passage 4 Injection Nozzle 5 Fuel Cutoff Valve (FCV)
6 Fuel addition valve (FDV)
7 Air purge valve (APV)
8, 9 Check valve 10 Pressure sensor 11 Control unit

Claims (3)

内燃機関の排気通路に後処理用の燃料を添加する後処理用燃料添加装置であって、
燃料供給源からの燃料供給通路と、空気供給源からの空気供給通路と、これら両通路を合流させた合流通路と、この合流通路の端部に接続されて前記排気通路に臨む噴射ノズルと、前記燃料供給通路の上流側に介装された燃料カットオフバルブと、前記燃料供給通路の下流側に介装された燃料添加バルブと、前記空気供給通路に介装された空気パージバルブと、前記燃料カットオフバルブ、前記燃料添加バルブ及び前記空気パージバルブの作動を制御する制御ユニットと、前記燃料供給通路における前記燃料カットオフバルブと前記燃料添加バルブとの間の圧力を検出する圧力センサと、を含んで構成され、
前記制御ユニットは、
前記燃料カットオフバルブを閉じ、前記空気パージバルブを閉じた後、前記燃料添加バルブを一時的に開いて再び閉じた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第1の故障診断モードと、
前記燃料カットオフバルブを閉じ、前記空気パージバルブ及び前記燃料添加バルブを開いた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第2の故障診断モードと、を有し、
少なくとも、エンジン始動直後に、前記第1の故障診断モード、前記第2の故障診断モードの順で、故障診断を行う
ことを特徴とする後処理用燃料添加装置。
An aftertreatment fuel addition device for adding aftertreatment fuel to an exhaust passage of an internal combustion engine,
A fuel supply passage from the fuel supply source, an air supply passage from the air supply source, a merge passage that joins both the passages, an injection nozzle that is connected to an end of the merge passage and faces the exhaust passage, A fuel cutoff valve interposed upstream of the fuel supply passage, a fuel addition valve interposed downstream of the fuel supply passage, an air purge valve interposed in the air supply passage, and the fuel A control unit that controls the operation of the cutoff valve, the fuel addition valve, and the air purge valve; and a pressure sensor that detects a pressure between the fuel cutoff valve and the fuel addition valve in the fuel supply passage. Consists of
The control unit is
Closing said fuel cutoff valve, wherein after closing the air purge valve, in the fuel addition condition in which the valve temporarily opened or closed again,-out based on the pressure detected by the pressure sensor, the threshold value In comparison, a first failure diagnosis mode for diagnosing the presence or absence of a failure,
Closing said fuel cutoff valve, in a state in which the open air purge valve and the fuel addition valve-out based on the pressure detected by the pressure sensor, in comparison with the threshold value, the diagnosing the presence or absence of a fault Two failure diagnosis modes ,
The post-processing fuel addition device , wherein failure diagnosis is performed in the order of the first failure diagnosis mode and the second failure diagnosis mode at least immediately after the engine is started .
前記制御ユニットは、前記燃料カットオフバルブを閉じ、前記空気パージバルブを閉じ、前記燃料添加バルブを開いた状態で、前記圧力センサにより検出される圧力に基づき、しきい値との比較で、故障の有無を診断する第3の故障診断モードを更に有することを特徴とする請求項1記載の後処理用燃料添加装置。 Wherein the control unit closes the fuel cutoff valve, closing the air purge valve, with open said fuel addition valve,-out based on the pressure detected by the pressure sensor, in comparison with the threshold value, The post-processing fuel addition apparatus according to claim 1, further comprising a third failure diagnosis mode for diagnosing the presence or absence of a failure. 前記制御ユニットは、少なくとも、エンジン始動直後に、前記第1の故障診断モード、前記第2の故障診断モード、前記第3の故障診断モードの順で、故障診断を行うことを特徴とする請求項2記載の後処理用燃料添加装置。 The control unit performs failure diagnosis in the order of the first failure diagnosis mode, the second failure diagnosis mode, and the third failure diagnosis mode at least immediately after engine startup. 2. A post-treatment fuel addition apparatus according to 2.
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