JP4464694B2 - PM accumulation amount judgment device - Google Patents

PM accumulation amount judgment device Download PDF

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JP4464694B2
JP4464694B2 JP2004011573A JP2004011573A JP4464694B2 JP 4464694 B2 JP4464694 B2 JP 4464694B2 JP 2004011573 A JP2004011573 A JP 2004011573A JP 2004011573 A JP2004011573 A JP 2004011573A JP 4464694 B2 JP4464694 B2 JP 4464694B2
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真人 小川
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Honda Motor Co Ltd
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Description

本発明は、ディーゼルエンジンの排気通路に設けられたＰＭトラップのＰＭ堆積量を判定するＰＭ堆積量判定装置に関する。   The present invention relates to a PM accumulation amount determination device that determines a PM accumulation amount of a PM trap provided in an exhaust passage of a diesel engine.

ディーゼルエンジンの排気通路には、排気ガス中のＰＭ（排気微粒子：Ｐａｒｔｉｃｕｌａｔｅ Ｍａｔｔｅｒ）を吸着して浄化処理するためのＰＭトラップが設けられる。ＰＭトラップは排気ガス中のＰＭをトラップして大気への放散を防止するフィルターで構成されており、車両の走行距離が増加するに伴ってＰＭトラップがＰＭにより目詰まりして圧損が発生するのを防止すべく、ディーゼルエンジンの排気行程においても燃料を噴射し、かつＰＭトラップに大量の空気を供給してＰＭを燃焼させるＰＭトラップ再生が行われる。ＰＭトラップ再生はＰＭトラップのＰＭ堆積量が所定値以上になる毎に行われるため、ＰＭ堆積量を測定する必要がある。   The exhaust passage of the diesel engine is provided with a PM trap for adsorbing and purifying PM (exhaust particulate matter) in the exhaust gas. The PM trap is composed of a filter that traps PM in the exhaust gas and prevents its emission to the atmosphere. As the mileage of the vehicle increases, the PM trap becomes clogged by PM and pressure loss occurs. In order to prevent this, PM trap regeneration is performed in which fuel is injected and a large amount of air is supplied to the PM trap to burn PM in the exhaust stroke of the diesel engine. Since the PM trap regeneration is performed every time the PM deposition amount of the PM trap becomes a predetermined value or more, it is necessary to measure the PM deposition amount.

下記特許文献１には、ＰＭトラップの上流および下流の圧力を圧力センサで測定し、この上流および下流の圧力差が所定値以上になるとＰＭトラップのＰＭ堆積量が限界に達したと判定してＰＭ再生を実行するものが記載されている。
特公平４−３６２４８号公報 In Patent Document 1 below, the pressure upstream and downstream of the PM trap is measured by a pressure sensor, and when the pressure difference between the upstream and downstream exceeds a predetermined value, it is determined that the PM deposition amount of the PM trap has reached the limit. What performs PM regeneration is described.
Japanese Patent Publication No. 4-36248

ところで、上記特許文献１に記載されたものは、ＰＭ堆積量の算出を排気ガスの流量と無関係に行っているため、排気ガスの流量が大きいときの圧力に耐え得るように圧力センサに定格の大きいものを使用する必要があった。しかしながら、定格の大きい圧力センサは、排気ガスの流量が小さいとき、つまり圧力が小さいときの測定誤差が大きくなるため、ＰＭ堆積量の算出誤差が大きくなる問題があった。   By the way, what is described in Patent Document 1 calculates the PM accumulation amount regardless of the flow rate of the exhaust gas. Therefore, the pressure sensor is rated so that it can withstand the pressure when the flow rate of the exhaust gas is large. It was necessary to use a larger one. However, a pressure sensor with a large rating has a problem that a measurement error when the flow rate of the exhaust gas is small, that is, when the pressure is small, increases a calculation error of the PM deposition amount.

また上記特許文献１に記載されたものは、所定の測定時間間隔で圧力の測定を行っているが、ＰＭトラップのＰＭ堆積量が小さく堆積限界に達するまでに余裕がある場合でも、必要以上に短い測定時間間隔で圧力の測定が行われるために、圧力センサがＰＭで汚損されて測定精度が低下する問題があった。   Moreover, although what was described in the said patent document 1 is measuring the pressure at a predetermined measurement time interval, even if there is a margin before the deposition limit of the PM trap is small and the deposition limit is reached, it is more than necessary. Since pressure is measured at a short measurement time interval, there is a problem in that the pressure sensor is contaminated with PM and the measurement accuracy is lowered.

本発明は前述の事情に鑑みてなされたもので、ディーゼルエンジンのＰＭトラップのＰＭ堆積量の判定精度を高めることを目的とする。   The present invention has been made in view of the above-described circumstances, and an object thereof is to improve the determination accuracy of the PM accumulation amount of a PM trap of a diesel engine.

上記目的を達成するために、請求項１に記載された発明によれば、ディーゼルエンジンの排気通路に設けられたＰＭトラップのＰＭ堆積量を判定するＰＭ堆積量判定装置において、ＰＭトラップ上流の排気通路から分岐してＰＭトラップ下流の排気通路に接続される分岐路にのみ設けられて該ＰＭトラップの上流及び下流の差圧の測定に専用される差圧センサと、分岐路を開閉する開閉バルブと、ＰＭトラップ上流の排気通路を流れる排気ガスの流量を算出する排気ガス流量算出手段と、排気ガス流量算出手段で算出した排気ガスの流量が所定値未満の場合には開閉バルブを開弁してＰＭトラップ上流の排気通路と差圧センサとを連通させ、またその排気ガスの流量が所定値以上の場合には開閉バルブを閉弁して前記連通を遮断する開閉バルブ制御手段と、差圧センサで測定した差圧に基づいてＰＭトラップのＰＭ堆積量を算出する堆積量算出手段とを備えたことを特徴とするＰＭ堆積量判定装置が提案される。 To achieve the above object, according to the invention described in claim 1, in the PM accumulation amount judgment device determines the amount of PM accumulated PM trap provided in an exhaust passage of a diesel engine, the PM trapped on the upstream a differential pressure sensor is provided only on the branch line connected to the exhaust passage of the PM trapped downstream dedicated to the measurement of the upper stream and downstream of the differential pressure of the PM trap is branched from the exhaust passage, for opening and closing the branch passage an opening and closing valve, and the exhaust gas flow rate calculating means for calculating the flow rate of the exhaust gas flowing through the PM trap upstream of the exhaust passage, the opening and closing valve when the flow rate of the exhaust gas calculated in the exhaust gas flow rate calculating means is less than a predetermined value to open An open / close valve that connects the exhaust passage upstream of the PM trap with the differential pressure sensor and closes the open / close valve to shut off the communication when the flow rate of the exhaust gas exceeds a predetermined value. There is proposed a PM deposition amount determination device comprising a control unit and a deposition amount calculation unit that calculates a PM deposition amount of a PM trap based on a differential pressure measured by a differential pressure sensor.

また請求項２に記載された発明によれば、ディーゼルエンジンの排気通路に設けられたＰＭトラップのＰＭ堆積量を判定するＰＭ堆積量判定装置であって、
ＰＭトラップ上流の排気通路から分岐する分岐路に設けられて該ＰＭトラップの上流及び下流の差圧を測定可能な差圧センサと、分岐路を開閉する開閉バルブと、ＰＭトラップ上流の排気通路を流れる排気ガスの流量を算出する排気ガス流量算出手段と、開閉バルブを開閉し得る開閉バルブ制御手段と、その開閉バルブ制御手段による開閉バルブの開弁でＰＭトラップ上流の排気通路と差圧センサとを連通させた時に差圧センサで測定した前記差圧に基づいてＰＭトラップのＰＭ堆積量を算出する堆積量算出手段とを備え、開閉バルブ制御手段は、排気ガス流量算出手段で算出した排気ガスの流量が所定値未満の場合に開閉バルブを開弁し且つその開弁後に堆積量算出手段がＰＭ堆積量を算出してから開閉バルブを閉弁するバルブ開閉制御を所定時間間隔で実行するものにおいて、
堆積量算出手段で算出したＰＭ堆積量の増加に応じて前記所定時間間隔を短くするよう変更する所定時間間隔変更手段を更に備えたことを特徴とするＰＭ堆積量判定装置が提案される。 According to the invention described in claim 2, a PM accumulation amount determination device for determining a PM accumulation amount of a PM trap provided in an exhaust passage of a diesel engine ,
And a differential pressure sensor capable of measuring is provided in the branch path on the upstream and downstream pressure difference of the PM trapping branched from the exhaust passage of the PM trapping upper stream, and the branch passage opens closes off valve, PM trap upstream of The exhaust gas flow rate calculating means for calculating the flow rate of the exhaust gas flowing through the exhaust passage, the open / close valve control means for opening / closing the open / close valve, and the opening / closing valve opening by the open / close valve control means differ from the exhaust passage upstream of the PM trap. A deposit amount calculating means for calculating a PM deposit amount of the PM trap based on the differential pressure measured by the differential pressure sensor when communicating with the pressure sensor, and the open / close valve control means is calculated by the exhaust gas flow rate calculating means. Valve opening / closing control is performed in which the opening / closing valve is opened when the flow rate of the exhaust gas is less than a predetermined value and the opening / closing valve is closed after the accumulation amount calculating means calculates the PM accumulation amount after the opening. In what is executed at predetermined time intervals,
PM accumulation amount judgment device is proposed, characterized by further comprising a constant-time interval changing means where to be modified to shorten the plant constant time intervals according to the increase of the calculated PM deposition amount in the deposition amount calculating means .

尚、実施例の差圧センサ２２は本発明の圧力センサに対応する。   The differential pressure sensor 22 of the embodiment corresponds to the pressure sensor of the present invention.

請求項１の構成によれば、ＰＭトラップ上流の排気通路から分岐する分岐路に設けた開閉バルブを開弁してＰＭトラップ上流の排気通路と差圧センサとを連通させることにより、差圧センサでＰＭトラップの上流及び下流の差圧を測定し、この差圧に基づいてＰＭトラップのＰＭ堆積量を算出する際に、排気ガスの流量が所定値未満の場合に限って開閉バルブを開弁するので、定格が小さく測定誤差が小さい差圧センサを用いてＰＭ堆積量の算出精度を高めながら、過剰な圧力による差圧センサの破損を回避することができる。 According to the configuration of claim 1, the differential pressure sensor is opened by opening an on-off valve provided in a branch path that branches from the exhaust passage upstream of the PM trap so that the exhaust passage upstream of the PM trap communicates with the differential pressure sensor. Measure the differential pressure upstream and downstream of the PM trap and calculate the PM accumulation amount of the PM trap based on this differential pressure , and open the open / close valve only when the flow rate of the exhaust gas is less than the predetermined value Therefore, it is possible to avoid damage to the differential pressure sensor due to excessive pressure while increasing the calculation accuracy of the PM deposition amount using a differential pressure sensor having a small rating and a small measurement error.

請求項２の構成によれば、ＰＭトラップ上流の排気通路から分岐する分岐路に設けた開閉バルブを所定時間間隔で開弁して差圧センサでＰＭトラップの上流及び下流の差圧を測定し、この差圧に基づいてＰＭトラップのＰＭ堆積量を算出する際に、そのＰＭ堆積量の増加に応じて前記所定時間間隔を短くするよう変更するので、ＰＭ堆積量が限界に達する可能性が低いときには差圧を測定する頻度を小さくしてＰＭによる差圧センサの汚れを最小限に抑えるとともに、ＰＭ堆積量が限界に達する可能性が高いときには差圧を測定する頻度を大きくしてＰＭ堆積量が限界に達したのを確実に判定することができる。 According to the second aspect, measuring the upstream and downstream differential pressure PM trapped in the differential pressure sensor by opening the opening and closing valve provided in the branch path which branches from the exhaust passage of the PM trapped upstream in Jo Tokoro time interval and, when calculating the amount of PM accumulated PM trapped on the basis of the differential pressure, since the changes to shorten the plant constant time intervals in accordance with an increase in the PM accumulation amount, can PM accumulation amount reaches a limit When the pressure is low, the frequency of measuring the differential pressure is reduced to minimize contamination of the differential pressure sensor by PM, and when the PM accumulation amount is likely to reach the limit, the frequency of measuring the differential pressure is increased. It is possible to reliably determine that the PM deposition amount has reached the limit.

以下、本発明の実施形態を、添付図面に示した本発明の実施例に基づいて説明する。   Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

図１〜図３は本発明の第１実施例を示すもので、図１はディーゼルエンジンの排気浄化装置の構成を示す図、図２は電子制御ユニットの回路を示すブロック図、図３は電子制御ユニットの作用を示すフローチャートである。   1 to 3 show a first embodiment of the present invention. FIG. 1 is a diagram showing a configuration of an exhaust emission control device for a diesel engine, FIG. 2 is a block diagram showing a circuit of an electronic control unit, and FIG. It is a flowchart which shows the effect | action of a control unit.

図１に示すように、ディーゼルエンジンＥの排気通路１１に、排気ガス中のＰＭを吸着して浄化処理するためのＰＭトラップ１３が設けられる。ディーゼルエンジンＥの吸気通路１４にエアクリーナ１５および燃料噴射弁１６が設けられており、エアクリーナ１５および燃料噴射弁１６の中間位置と、排気通路１１のＰＭトラップ１３よりも上流位置とを接続する空気供給通路１７に、エアポンプ１８およびエアバルブ１９が配置される。排気通路１１のＰＭトラップ１３よりも上流位置および下流位置がバイパスを構成する分岐路２０で接続されており、この分岐路２０に上流側の開閉バルブ２１と下流側の差圧センサ２２とが配置される。開閉バルブ２１は、開弁時に差圧センサ２２の上流側を排気通路１１に連通させ、閉弁時に差圧センサ２２の上流側を大気に連通させる。   As shown in FIG. 1, a PM trap 13 for adsorbing and purifying PM in exhaust gas is provided in the exhaust passage 11 of the diesel engine E. An air cleaner 15 and a fuel injection valve 16 are provided in the intake passage 14 of the diesel engine E, and an air supply that connects an intermediate position between the air cleaner 15 and the fuel injection valve 16 and a position upstream of the PM trap 13 in the exhaust passage 11. An air pump 18 and an air valve 19 are disposed in the passage 17. An upstream position and a downstream position from the PM trap 13 of the exhaust passage 11 are connected by a branch path 20 that constitutes a bypass, and an upstream on-off valve 21 and a downstream differential pressure sensor 22 are arranged in the branch path 20. Is done. The on-off valve 21 communicates the upstream side of the differential pressure sensor 22 to the exhaust passage 11 when the valve is opened, and communicates the upstream side of the differential pressure sensor 22 to the atmosphere when the valve is closed.

排気ガス中のＰＭをトラップして大気への放散を防止するフィルターよりなるＰＭトラップ１３が目詰まりすると、排気通路１１に圧損が発生してディーゼルエンジンＥの出力が低下する問題がある。そこで、ＰＭトラップ１３にトラップされたＰＭを燃焼させて浄化するＰＭトラップ再生を実行すべく、エンジン回転数センサ２３、燃料噴射量検出センサ２４および前記差圧センサ２２からの信号が入力される電子制御ユニットＵは、燃焼噴射弁１６、エアポンプ１８、エアバルブ１９および開閉バルブ２１の作動を制御する。   If the PM trap 13 made of a filter that traps PM in the exhaust gas and prevents its emission to the atmosphere is clogged, there is a problem that pressure loss occurs in the exhaust passage 11 and the output of the diesel engine E decreases. Therefore, in order to execute the PM trap regeneration that burns and purifies the PM trapped in the PM trap 13, the signals from the engine speed sensor 23, the fuel injection amount detection sensor 24, and the differential pressure sensor 22 are input. The control unit U controls the operation of the combustion injection valve 16, the air pump 18, the air valve 19 and the opening / closing valve 21.

図２に示すように、電子制御ユニットＵは、排気ガス流量算出手段Ｍ１と、堆積量算出手段Ｍ２と、所定時間間隔変更手段Ｍ３と、開閉バルブ制御手段Ｍ４と、ＰＭトラップ再生手段Ｍ５とを備える。 2, the electronic control unit U includes an exhaust gas flow rate calculation means M1, and the deposition amount calculating means M2, a Jo Tokoro time interval changing means M3, and the on-off valve control means M4, the PM trap regeneration means M5 Is provided.

排気ガス流量算出手段Ｍ１は、エンジン回転数センサ２３で検出したエンジン回転数と、燃料噴射量検出センサ２４で検出した燃料噴射量とから、排気通路１１を流れる排気ガスの流量を３次元マップの検索により算出する。堆積量算出手段Ｍ２は、排気ガスの流量と、差圧センサ２２で測定したＰＭトラップ１３の上流および下流の差圧とから、ＰＭトラップ１３のＰＭ堆積量を算出する。   The exhaust gas flow rate calculation means M1 determines the flow rate of the exhaust gas flowing through the exhaust passage 11 from the engine speed detected by the engine speed sensor 23 and the fuel injection amount detected by the fuel injection amount detection sensor 24 in a three-dimensional map. Calculate by searching. The accumulation amount calculation means M2 calculates the PM accumulation amount of the PM trap 13 from the flow rate of the exhaust gas and the differential pressure upstream and downstream of the PM trap 13 measured by the differential pressure sensor 22.

所定時間間隔変更手段Ｍ３は、堆積量算出手段Ｍ２で算出したＰＭ堆積量が第１閾値以上になると、差圧センサ２２による差圧を測定する所定時間間隔を、第１の所定時間間隔から、それよりも短い第２の所定時間間隔へと変更する。開閉バルブ制御手段Ｍ４は、前記第１の所定時間間隔あるいは前記第２の所定時間間隔で開閉バルブ２１を開弁制御し、排気通路１１を差圧センサ２２に連通させる。また開閉バルブ制御手段Ｍ４は、排気ガス流量算出手段Ｍ１が算出した排気ガスの流量が所定値以上のときに開閉バルブ２１の開弁を禁止し、排気ガスの流量が所定値未満のときに開閉バルブ２１の開弁を許可する。 Jo Tokoro time interval changing means M3, when the PM deposition amount calculated in accumulation amount calculation means M2 is equal to or greater than the first threshold value, the constant time interval where measuring the differential pressure by the differential pressure sensor 22, the first place the constant time from the interval, changing to shorter than second predetermined constant time interval. Off valve control means M4, the opening and closing valve 21 opens the control in the first place the constant time interval or the second predetermined constant time interval, communicates the exhaust passage 11 to the differential pressure sensor 22. The on-off valve control means M4 prohibits opening of the on-off valve 21 when the exhaust gas flow rate calculated by the exhaust gas flow rate calculation means M1 is greater than or equal to a predetermined value, and opens and closes when the exhaust gas flow rate is less than the predetermined value. The valve 21 is allowed to open.

ＰＭトラップ再生手段Ｍ５は、堆積量算出手段Ｍ２で算出したＰＭ堆積量が第２閾値以上になると、ＰＭトラップ１３の再生を実行する。具体的には、ディーゼルエンジンＥの排気行程においても燃料噴射弁１６から燃料を噴射するとともに、エアポンプ１８を駆動してエアバルブ１９を開弁することでＰＭトラップ１３に大量の空気を供給して堆積したＰＭを燃焼させる。   The PM trap regeneration means M5 performs regeneration of the PM trap 13 when the PM accumulation amount calculated by the accumulation amount calculation means M2 becomes equal to or greater than the second threshold value. Specifically, during the exhaust stroke of the diesel engine E, fuel is injected from the fuel injection valve 16 and a large amount of air is supplied to the PM trap 13 by driving the air pump 18 and opening the air valve 19. Burn PM.

上記作用を図３のフローチャートに基づいて更に説明する。   The above operation will be further described based on the flowchart of FIG.

先ずステップＳ１で第１の所定時間間隔が経過すると、排気ガス流量算出手段Ｍ１が、ステップＳ２でエンジン回転数センサ２３で検出したエンジン回転数と、燃料噴射量検出センサ２４で検出した燃料噴射量とを読み込むとともに、ステップＳ３でエンジン回転数および燃料噴射量から排気ガスの流量を算出する。 First, when the first place a constant time interval in step S1 has passed, the exhaust gas flow rate calculating means M1, the engine speed detected by the engine speed sensor 23 in step S2, the fuel injection detected by the fuel injection amount detection sensor 24 In step S3, the flow rate of the exhaust gas is calculated from the engine speed and the fuel injection amount.

続くステップＳ４で排気ガスの流量が所定値未満であれば、ステップＳ５で開閉バルブ制御手段Ｍ４が開閉バルブ２１を開弁して排気通路１１を差圧センサ２２に連通させ、ステップＳ６でＰＭトラップ１３の上流および下流の差圧を測定する。そしてステップＳ７で堆積量算出手段Ｍ２が排気ガスの流量および前記差圧からＰＭトラップ１３のＰＭ堆積量を算出した後に、ステップＳ８で開閉バルブ制御手段Ｍ４が開閉バルブ２１を閉弁して排気通路１１と差圧センサ２２との連通を遮断する。前記ステップＳ７で算出したＰＭ堆積量が小さいときはＰＭトラップ１３が目詰まりしておらず、排気ガスが通過し易いために前記差圧が減少し、逆にＰＭ堆積量が大きいときはＰＭトラップ１３が目詰まりしており、排気ガスが通過し難いために前記差圧が増加する。   If the flow rate of the exhaust gas is less than the predetermined value in the subsequent step S4, the on-off valve control means M4 opens the on-off valve 21 in step S5 to connect the exhaust passage 11 to the differential pressure sensor 22, and the PM trap in step S6. Thirteen upstream and downstream differential pressures are measured. In step S7, the accumulation amount calculating means M2 calculates the PM accumulation amount of the PM trap 13 from the exhaust gas flow rate and the differential pressure, and then in step S8, the opening / closing valve control means M4 closes the opening / closing valve 21 to exhaust the exhaust passage. 11 and the differential pressure sensor 22 are disconnected. When the PM accumulation amount calculated in step S7 is small, the PM trap 13 is not clogged and the exhaust gas easily passes, so the differential pressure decreases. Conversely, when the PM accumulation amount is large, the PM trap 13 is clogged, and the differential pressure increases because it is difficult for exhaust gas to pass through.

続くステップＳ９でＰＭ堆積量が第１閾値以上であれば、ステップＳ１０で前記第１の所定時間間隔をそれよりも短い第２の所定時間間隔に変更する。そして前記ステップＳ１〜Ｓ１０を繰り返す間に、ステップＳ１１でＰＭ堆積量が前記第１閾値よりも大きい第２閾値以上になれば、ステップＳ１２でＰＭトラップ１３の再生を実行した後、ステップＳ１３で所定時間間隔を第２の所定時間間隔から第１の所定時間間隔に戻して本プログラムを終了する。 If the PM accumulation amount at the subsequent step S9, the first threshold value or more, is changed to a short second predetermined constant time interval than the first predetermined constant time interval in step S10. And while repeating the steps S1 to S10, if the second threshold value or more larger than the amount of PM deposits the first threshold value in step S11, after executing the regeneration of the PM trap 13 at step S12, Tokoro in step S13 the constant time interval back from the second place the constant time interval in the first place a constant time interval by terminating the program.

以上のように、排気ガスの流量が所定値未満の場合に限って開閉バルブ２１を開弁して差圧センサ２２による差圧の測定を許可するので、測定する差圧の定格が小さい差圧センサ２２を用いることができる。差圧センサ２２の測定誤差は検出する差圧の定格に比例するため、定格の小さい差圧センサ２２を用いることで測定誤差を最小限に抑えることができる。定格の小さい差圧センサ２２は耐圧性に乏しいために大きな差圧が作用すると破損する可能性があるが、差圧が大きくなる排気ガスの大流量時に開閉バルブ２１を閉弁することで差圧センサ２２の破損を防止することができる。逆に定格の大きい差圧センサ２２を用いると差圧による破損の心配はないが、差圧が小さくなる排気ガスの小流量時に測定誤差が増加してしまう。   As described above, only when the flow rate of the exhaust gas is less than the predetermined value, the on-off valve 21 is opened and the differential pressure measurement by the differential pressure sensor 22 is permitted. A sensor 22 can be used. Since the measurement error of the differential pressure sensor 22 is proportional to the rating of the differential pressure to be detected, the measurement error can be minimized by using the differential pressure sensor 22 with a small rating. Since the differential pressure sensor 22 with a small rating is poor in pressure resistance, there is a possibility that it will be damaged if a large differential pressure is applied. However, the differential pressure sensor 22 is closed by closing the open / close valve 21 at a large flow rate of exhaust gas. Damage to the sensor 22 can be prevented. Conversely, when the differential pressure sensor 22 having a large rating is used, there is no fear of damage due to the differential pressure, but the measurement error increases when the exhaust gas has a small flow rate where the differential pressure becomes small.

またＰＭ堆積量が第１閾値未満であれば比較的に長い第１の所定時間間隔で開閉バルブ２１の開弁、即ち差圧の測定を行い、ＰＭ堆積量が第１閾値以上であれば比較的に短い第２の所定時間間隔で開閉バルブ２１の開弁、即ち差圧の測定を行うので、ＰＭ堆積量が限界に達する可能性が低いときには差圧を測定する頻度を小さくしてＤＰによる差圧センサ２２の汚れを最小限に抑えるとともに、ＰＭ堆積量が限界に達する可能性が高いときには差圧を測定する頻度を大きくしてＰＭ堆積量が限界に達したのを確実に判定することができる。 The PM accumulation amount opening of the opening and closing valve 21 at relatively long first place the constant time interval is less than the first threshold value, i.e. perform the measurement of differential pressure, if the PM deposition amount is not smaller than the first threshold value relatively short second predetermined opening of the opening and closing valve 21 at constant time intervals, that is, the measurement of differential pressure, when there is a low possibility that the PM deposition amount reaches the limit by reducing the frequency of measuring a differential pressure In addition to minimizing the contamination of the differential pressure sensor 22 due to DP, and when there is a high possibility that the PM deposition amount will reach the limit, the frequency of measuring the differential pressure is increased to reliably determine that the PM deposition amount has reached the limit. can do.

以上、本発明の実施例を説明したが、本発明はその要旨を逸脱しない範囲で種々の設計変更を行うことが可能である。   Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

例えば、実施例の開閉バルブ２１は、開弁により差圧センサ２２を排気通路１１に連通させ、閉弁により差圧センサ２２を大気に連通させるものであるが、図４に示す第２実施例の如く、差圧センサ２２をバイパスするバイパス通路２５の上流端に開閉バルブ２１を設け、開閉バルブ２１の開弁によりバイパス通路２５を閉塞して差圧センサ２２を排気通路１１に連通させ、開閉バルブ２１の閉弁によりバイパス通路２５を開放して差圧センサ２２と排気通路１１との連通を遮断しても良い。   For example, the on-off valve 21 of the embodiment is configured to connect the differential pressure sensor 22 to the exhaust passage 11 by opening the valve and to connect the differential pressure sensor 22 to the atmosphere by closing the valve, but the second embodiment shown in FIG. As described above, the opening / closing valve 21 is provided at the upstream end of the bypass passage 25 that bypasses the differential pressure sensor 22, the bypass passage 25 is closed by opening the opening / closing valve 21, and the differential pressure sensor 22 is communicated with the exhaust passage 11. The bypass passage 25 may be opened by closing the valve 21 to block communication between the differential pressure sensor 22 and the exhaust passage 11.

また実施例では開閉バルブ２１を開弁する所定時間間隔を２段階に制御しているが、それを３段階以上に制御しても良い。 Although in the embodiment controls the constant time interval where opening the opening and closing valve 21 in two stages may be controlled it in three or more stages.

また実施例では排気ガスの流量を３次元マップの検索により算出しているが、エアフロメータで検出した吸気の流量から算出することも可能である。   In the embodiment, the flow rate of the exhaust gas is calculated by searching a three-dimensional map. However, it can be calculated from the flow rate of the intake air detected by the air flow meter.

第１実施例に係るディーゼルエンジンの排気浄化装置の構成を示す図The figure which shows the structure of the exhaust gas purification apparatus of the diesel engine which concerns on 1st Example. 電子制御ユニットの回路を示すブロック図Block diagram showing the circuit of the electronic control unit 電子制御ユニットの作用を示すフローチャートFlow chart showing operation of electronic control unit 第２実施例に係るディーゼルエンジンの排気浄化装置の構成を示す図The figure which shows the structure of the exhaust gas purification apparatus of the diesel engine which concerns on 2nd Example.

１１ 排気通路
１３ ＰＭトラップ
２０ 分岐路
２１ 開閉バルブ
２２ 差圧センサ（圧力センサ）
Ｅ ディーゼルエンジン
Ｍ１ 排気ガス流量算出手段
Ｍ２ 堆積量算出手段
Ｍ３ 所定時間間隔変更手段
Ｍ４ 開閉バルブ制御手段 11 Exhaust passage 13 PM trap 20 Branch passage 21 Open / close valve 22 Differential pressure sensor (pressure sensor)
E diesel engine M1 exhaust gas flow rate calculating means M2 deposition amount calculating means M3 at a constant time interval changing means M4-off valve control means

Claims (2)

ディーゼルエンジン（Ｅ）の排気通路（１１）に設けられたＰＭトラップ（１３）のＰＭ堆積量を判定するＰＭ堆積量判定装置において、
ＰＭトラップ（１３）上流の排気通路（１１）から分岐してＰＭトラップ（１３）下流の排気通路（１１）に接続される分岐路（２０）にのみ設けられて該ＰＭトラップ（１３）の上流及び下流の差圧の測定に専用される差圧センサ（２２）と、
分岐路（２０）を開閉する開閉バルブ（２１）と、
ＰＭトラップ（１３）上流の排気通路（１１）を流れる排気ガスの流量を算出する排気ガス流量算出手段（Ｍ１）と、
排気ガス流量算出手段（Ｍ１）で算出した排気ガスの流量が所定値未満の場合には開閉バルブ（２１）を開弁してＰＭトラップ（１３）上流の排気通路（１１）と差圧センサ（２２）とを連通させ、またその排気ガスの流量が所定値以上の場合には開閉バルブ（２１）を閉弁して前記連通を遮断する開閉バルブ制御手段（Ｍ４）と、
差圧センサ（２２）で測定した差圧に基づいてＰＭトラップ（１３）のＰＭ堆積量を算出する堆積量算出手段（Ｍ２）と
を備えたことを特徴とするＰＭ堆積量判定装置。 In the PM accumulation amount determination device for determining the PM accumulation amount of the PM trap (13) provided in the exhaust passage (11) of the diesel engine (E),
PM trap (13) is branched from the exhaust passage on the upstream (11) PM trap (13) downstream of the exhaust passage (11) connected to the branch channel (20) only provided with the PM trap (13) differential pressure sensor which is dedicated to the measurement of the upper stream and downstream of the differential pressure (22),
An open / close valve (21) for opening and closing the branch path (20);
Exhaust gas flow rate calculating means (M1) for calculating the flow rate of exhaust gas flowing through the exhaust passage (11 ) upstream of the PM trap (13) ;
When the flow rate of the exhaust gas calculated by the exhaust gas flow rate calculation means (M1) is less than a predetermined value, the on- off valve (21) is opened and the exhaust passage (11) upstream of the PM trap (13) and the differential pressure sensor ( And an open / close valve control means (M4) for closing the open / close valve (21) when the flow rate of the exhaust gas is equal to or greater than a predetermined value ;
A PM deposition amount determination device comprising: a deposition amount calculation means (M2) for calculating a PM deposition amount of the PM trap (13) based on the differential pressure measured by the differential pressure sensor (22). ディーゼルエンジン（Ｅ）の排気通路（１１）に設けられたＰＭトラップ（１３）のＰＭ堆積量を判定するＰＭ堆積量判定装置であって、
ＰＭトラップ（１３）上流の排気通路（１１）から分岐する分岐路（２０）に設けられて該ＰＭトラップ（１３）の上流及び下流の差圧を測定可能な差圧センサ（２２）と、
分岐路（２０）を開閉する開閉バルブ（２１）と、
ＰＭトラップ（１３）上流の排気通路（１１）を流れる排気ガスの流量を算出する排気ガス流量算出手段（Ｍ１）と、
開閉バルブ（２１）を開閉し得る開閉バルブ制御手段（Ｍ４）と、
その開閉バルブ制御手段（Ｍ４）による開閉バルブ（２１）の開弁でＰＭトラップ（１３）上流の排気通路（１１）と差圧センサ（２２）とを連通させた時に差圧センサ（２２）で測定した前記差圧に基づいてＰＭトラップ（１３）のＰＭ堆積量を算出する堆積量算出手段（Ｍ２）とを備え、
開閉バルブ制御手段（Ｍ４）は、排気ガス流量算出手段（Ｍ１）で算出した排気ガスの流量が所定値未満の場合に開閉バルブ（２１）を開弁し且つその開弁後に堆積量算出手段（Ｍ２）がＰＭ堆積量を算出してから開閉バルブ（２１）を閉弁するバルブ開閉制御を所定時間間隔で実行するものにおいて、
堆積量算出手段（Ｍ２）で算出したＰＭ堆積量の増加に応じて前記所定時間間隔を短くするよう変更する所定時間間隔変更手段（Ｍ３）を更に備えたことを特徴とするＰＭ堆積量判定装置。 A PM accumulation amount determination device for determining a PM accumulation amount of a PM trap (13) provided in an exhaust passage (11) of a diesel engine (E) ,
PM trap (13) branching path that branches from the exhaust passage on the upstream (11) capable of measuring a differential pressure sensor on the upstream and downstream pressure difference provided (20) with the PM trap (13) (22) ,
Branch channel (20) open closes off valve (21),
Exhaust gas flow rate calculating means (M1) for calculating the flow rate of exhaust gas flowing through the exhaust passage (11) upstream of the PM trap (13);
Open / close valve control means (M4) capable of opening and closing the open / close valve (21);
When the open / close valve (21) is opened by the open / close valve control means (M4) and the exhaust passage (11) upstream of the PM trap (13) communicates with the differential pressure sensor (22), the differential pressure sensor (22) A deposition amount calculating means (M2) for calculating a PM deposition amount of the PM trap (13) based on the measured differential pressure ;
The on-off valve control means (M4) opens the on-off valve (21) when the exhaust gas flow rate calculated by the exhaust gas flow rate calculation means (M1) is less than a predetermined value, and after the opening, the accumulated amount calculation means ( M2) performs valve opening / closing control for closing the opening / closing valve (21) after calculating the PM accumulation amount at predetermined time intervals,
PM accumulation amount, wherein, further comprising a constant-time interval changing means where change (M3) so as to shorten the plant constant time intervals according to the increase of the calculated PM deposition amount in the deposition amount calculating means (M2) Judgment device.
JP2004011573A 2004-01-20 2004-01-20 PM accumulation amount judgment device Expired - Fee Related JP4464694B2 (en)

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