JP2008144609A - Failure determining method of egr system and failure determining system of egr system - Google Patents

Failure determining method of egr system and failure determining system of egr system Download PDF

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JP2008144609A
JP2008144609A JP2006329873A JP2006329873A JP2008144609A JP 2008144609 A JP2008144609 A JP 2008144609A JP 2006329873 A JP2006329873 A JP 2006329873A JP 2006329873 A JP2006329873 A JP 2006329873A JP 2008144609 A JP2008144609 A JP 2008144609A
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bypass
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valve
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JP5011990B2 (en
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Kazumi Yamaguchi
一実 山口
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Isuzu Motors Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure determining method of an EGR system, and a failure determining system of the EGR system, capable of determining the existence of failure in an EGR cooler and the existence of failure due to a sticking bypass control valve for adjusting the flow rate ratio of EGR gas flowing in the EGR cooler and a bypass passage bypassing the EGR cooler, in the EGR system. <P>SOLUTION: The temperatures Tm1 and Tm2 of gas of an EGR passage 13 or an intake system passage 12 on the downstream side of a confluent part 13b of the bypass passage 15 and the EGR passage 13 are measured. The temperature Ts of the gas in a position for measuring the temperature of the EGR gas is estimated based on a state detected in a vehicle. The existence of failure of the EGR system 10 is determined based on the measured temperatures Tm1 and Tm2 and the estimated temperature Ts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、ＥＧＲシステムにおいて、ＥＧＲクーラの故障の有無と、ＥＧＲクーラとＥＧＲクーラを迂回するバイパス通路とへ流入するＥＧＲガスの流量比を調整するバイパス制御弁の固着による故障の有無を判定できるＥＧＲシステムの故障判定方法及びＥＧＲシステムの故障判定システムに関する。   In the EGR system, it is possible to determine whether or not there is a failure in the EGR cooler and whether or not there is a failure due to sticking of a bypass control valve that adjusts the flow rate ratio of the EGR gas flowing into the bypass passage that bypasses the EGR cooler and the EGR cooler. The present invention relates to a failure determination method for an EGR system and a failure determination system for an EGR system.

車両に搭載する内燃機関等においては、排気ガス中のＮＯｘ（窒素酸化物）の低減と燃費の向上のために、排気ガスの一部を吸気側に再循環させて、吸入空気と混合することで、燃焼室内の酸素濃度を抑制し、燃焼を穏やかにして燃焼温度を低下させるＥＧＲ（Exhaust Gas Recirculation ：排気再循環）が行なわれている。この燃焼温度の低下により、高温燃焼時に生成されるＮＯｘを減少させることができる。   In an internal combustion engine mounted on a vehicle, a part of the exhaust gas is recirculated to the intake side and mixed with intake air in order to reduce NOx (nitrogen oxide) in the exhaust gas and improve fuel efficiency. Therefore, EGR (Exhaust Gas Recirculation) is performed in which the oxygen concentration in the combustion chamber is suppressed, the combustion is moderated, and the combustion temperature is lowered. This reduction in combustion temperature can reduce NOx generated during high temperature combustion.

このＥＧＲシステムでは、排気系通路から吸気系通路へ排気ガスの一部であるＥＧＲガスを流すためにＥＧＲ通路が設けられ、このＥＧＲ通路にはＥＧＲガスを冷却するためのＥＧＲクーラとＥＧＲガス量（ＥＧＲ率）を調整するためのＥＧＲ弁が配設されている。ＥＧＲクーラは、通常は多数の微小管で構成され、微小管内にＥＧＲガスを流し、外部に冷却用媒体（空気や冷却水）を流して、ＥＧＲガスを冷却している。   In this EGR system, an EGR passage is provided for flowing EGR gas that is a part of exhaust gas from the exhaust system passage to the intake system passage, and an EGR cooler and an amount of EGR gas for cooling the EGR gas are provided in the EGR passage. An EGR valve for adjusting (EGR rate) is provided. The EGR cooler is usually composed of a large number of microtubes, and EGR gas is allowed to flow through the microtubes, and a cooling medium (air or cooling water) is allowed to flow outside to cool the EGR gas.

最近のＥＧＲシステムでは、このＥＧＲクーラによりＥＧＲガスの過冷却を防止するために、ＥＧＲクーラを迂回するバイパス通路とバイパス制御弁が設けられ、このバイパス制御弁の弁の開閉制御により、ＥＧＲクーラに流れるＥＧＲガスの割り合いを調整してＥＧＲガスの温度調整を行なっている。   In recent EGR systems, in order to prevent overcooling of the EGR gas by the EGR cooler, a bypass passage that bypasses the EGR cooler and a bypass control valve are provided, and the EGR cooler is controlled by opening and closing the valve of the bypass control valve. The ratio of the flowing EGR gas is adjusted to adjust the temperature of the EGR gas.

しかしながら、このバイパス制御弁が、排気ガス中の煤等により固着したりして故障すると、エンジン暖気後に、ＥＧＲクーラを迂回できなくなる等、ＥＧＲガスの温度調整ができなくなり、内燃機関の燃焼状態が悪化し、排気ガスの状態も悪化するという問題がある。また、ＥＧＲクーラも微小管で形成されるため、目つまり等が発生する恐れもある。そのため、これらのバイパス制御弁の故障やＥＧＲクーラの故障を検出する必要がある。   However, if this bypass control valve malfunctions due to sticking or the like in the exhaust gas, the EGR gas temperature cannot be adjusted after the engine warms up, for example, the EGR gas temperature cannot be adjusted, and the combustion state of the internal combustion engine There is a problem that the exhaust gas condition deteriorates. Further, since the EGR cooler is also formed of microtubules, there is a possibility that eyes are clogged. Therefore, it is necessary to detect failure of these bypass control valves and failure of the EGR cooler.

このバイパス制御弁の固着を検出する方法として、吸気絞り弁及びＥＧＲ弁が全開であるときに、バイパス通路を全開及び全閉させるようにバイパス制御弁を制御し、全開制御時の吸入空気量と全閉制御時の吸入吸気量とが略等しいときにバイパス制御弁が固着していると判定する内燃機関のＥＧＲ機構が提案されている（例えば、特許文献１参照。）。   As a method of detecting the sticking of the bypass control valve, when the intake throttle valve and the EGR valve are fully open, the bypass control valve is controlled so as to fully open and close the bypass passage, There has been proposed an EGR mechanism for an internal combustion engine that determines that the bypass control valve is fixed when the intake air intake amount during the fully closed control is substantially equal (see, for example, Patent Document 1).

しかしながら、この判定方法では、バイパス通路とＥＧＲクーラの両方で排気圧力損失があることを前提としており、ＥＧＲクーラ側の排気通過面積を大きくして排気圧力損失をバイパス通路と等しくした場合には使用できないという問題がある。また、吸気絞り弁及びＥＧＲ弁が全開であるときに、バイパス通路を全開及び全閉させるようにバイパス制御弁を制御するため、内燃機関が正常状態であるにもかかわらず、排気圧力が異なるバイパス通路とＥＧＲクーラとを切り替えるので、排気音が変化し、ドライバーへの印象が悪化するという問題もある。
特開２００３−２４７４５９号公報 However, this determination method assumes that there is exhaust pressure loss in both the bypass passage and the EGR cooler, and is used when the exhaust passage loss on the EGR cooler side is increased to make the exhaust pressure loss equal to the bypass passage. There is a problem that you can not. In addition, when the intake throttle valve and the EGR valve are fully open, the bypass control valve is controlled so as to fully open and close the bypass passage. Since the passage and the EGR cooler are switched, there is a problem that the exhaust sound changes and the impression to the driver is deteriorated.
Japanese Patent Laid-Open No. 2003-247459

本発明は、上記の問題を解決するためになされたものであり、その目的は、ＥＧＲシステムにおいて、ＥＧＲクーラとバイパス通路の排気圧力損失が等しい場合でも使用でき、エンジンが正常なときにＥＧＲクーラとバイパス通路との切り替えを行なうことなく、ＥＧＲクーラの故障の有無と、バイパス制御弁の固着による故障の有無を判定できるＥＧＲシステムの故障判定方法及びＥＧＲシステムの故障判定システムを提供することにある。   The present invention has been made to solve the above-described problems, and the object of the present invention is to use the EGR system even when the exhaust gas pressure loss of the EGR cooler and the bypass passage is equal, and when the engine is normal, the EGR cooler is used. To provide a failure determination method for an EGR system and a failure determination system for an EGR system that can determine whether or not there is a failure in an EGR cooler and whether or not there is a failure due to adhesion of a bypass control valve without switching between the bypass passage and the bypass passage. .

上記の目的を達成するための本発明のＥＧＲシステムの故障判定方法は、内燃機関の排気系から吸気系への排気の一部であるＥＧＲガスを還流させるＥＧＲ通路にＥＧＲガスを冷却するＥＧＲクーラを設置し、該ＥＧＲクーラを迂回するバイパス通路を設け、該バイパス通路に流れるＥＧＲガスの流量を調整するバイパス制御弁と、該バイパス制御弁を制御する弁制御部を備えたＥＧＲシステムの故障判定方法において、前記バイパス通路と前記ＥＧＲ通路との合流部位よりも下流側の前記ＥＧＲ通路又は吸気系通路のガスの温度を測定すると共に、車両にて検出した状態に基づいて前記ガスの温度を測定する位置のガスの温度を推定し、前記バイパス制御弁の弁開閉の制御信号と、前記測定温度と、前記推定温度とに基づいて、該ＥＧＲシステムの故障の有無を判定することを特徴とする。   In order to achieve the above object, a failure determination method for an EGR system according to the present invention includes an EGR cooler that cools EGR gas into an EGR passage that recirculates EGR gas that is part of exhaust gas from an exhaust system of an internal combustion engine to an intake system. EGR system failure determination including a bypass control valve that adjusts the flow rate of EGR gas flowing through the bypass passage, and a valve control unit that controls the bypass control valve. In the method, the temperature of the gas in the EGR passage or the intake system passage downstream from the joining portion of the bypass passage and the EGR passage is measured, and the temperature of the gas is measured based on a state detected by the vehicle. A gas position at a position to be operated is estimated, and based on the control signal for opening and closing the bypass control valve, the measured temperature, and the estimated temperature, the EGR And judging the presence or absence of failure systems out.

この車両にて検出した状態に基づいてとは、外気温度、排気温度、吸気圧、ＥＧＲ弁の開度等によって推定温度を算出することを言い、言い換えれば、これらを引数とする関数で推定温度を算出することをいう。   Based on the state detected by this vehicle means that the estimated temperature is calculated by the outside air temperature, the exhaust temperature, the intake pressure, the opening degree of the EGR valve, etc., in other words, the estimated temperature by a function having these as arguments. Is calculated.

この故障判定方法によれば、弁制御部がＥＧＲクーラを排気ガスに流すように、バイパス制御弁に制御信号を出しているときに、ＥＧＲガス又は混合ガスのガスの温度をモニターすることで、ＥＧＲクーラの故障やバイパス制御弁の固着を検出するので、ＥＧＲクーラ側の排気通過面積を大きくして排気圧力損失をバイパス通路と等しくした場合でも使用でき、また、バイパス制御弁の故障のみならず、ＥＧＲクーラの故障も検出できる。   According to this failure determination method, when the valve control unit outputs a control signal to the bypass control valve so that the EGR cooler flows into the exhaust gas, by monitoring the temperature of the EGR gas or the mixed gas, EGR cooler failure and bypass control valve sticking are detected, so it can be used even when the exhaust passage area on the EGR cooler side is increased to make the exhaust pressure loss equal to the bypass passage. A failure of the EGR cooler can also be detected.

また、ＥＧＲクーラの搭載目的であるＥＧＲクーラ通過後のＥＧＲガス又は混合ガスのガスの温度が意図した温度になっているかをモニターするので、吸気弁やＥＧＲ弁が開等の前提条件が不要となり、ＥＧＲシステムの稼働中に簡易に故障を判定することができる。   In addition, it monitors whether the temperature of the EGR gas or mixed gas after passing through the EGR cooler, which is the purpose of mounting the EGR cooler, is the intended temperature, eliminating the need for preconditions such as opening the intake valve and EGR valve. A failure can be easily determined during operation of the EGR system.

更に、排気圧力が異なる通路、すなわち、ＥＧＲクーラの有る通路とバイパス通路を切り換えるバイパス制御弁を故障判定のためだけに作動させる必要が無くなる。そのため、排気圧力損失の異なる通路への切り替えが無いので、この切り替えに伴う排気音の変化が無くなり、バイパス制御弁を切り替え作動させることで故障判定を行なう故障判定システムと比較して不用意に耳障りな排気音の変化を発生させることがない。   Furthermore, it is not necessary to operate a bypass control valve for switching between passages having different exhaust pressures, that is, a passage having an EGR cooler and a bypass passage only for failure determination. Therefore, since there is no switching to a passage with a different exhaust pressure loss, there is no change in the exhaust sound due to this switching, and it is inadvertently inferior compared with a failure determination system that performs failure determination by switching the bypass control valve. No change in exhaust noise.

この故障判定方法は、実際のバイパス制御弁の弁開閉に基づくものではなく、弁制御部のバイパス制御弁への弁開閉のための制御信号に基づいて行なわれる。従って、バイパス制御弁が故障している場合には、弁制御部から弁開閉の制御信号を出したものの、バイパス制御弁自体は動作しないことも考えられる。この故障判定ではこのバイパス制御弁の故障判定も行なう。   This failure determination method is not based on actual opening / closing of the bypass control valve, but based on a control signal for opening / closing the bypass control valve of the valve control unit. Therefore, when the bypass control valve is out of order, it is possible that the valve control unit outputs a valve opening / closing control signal, but the bypass control valve itself does not operate. In this failure determination, the failure determination of this bypass control valve is also performed.

上記のＥＧＲシステムの故障判定方法において、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の前記測定温度と前記推定温度を比較し、前記測定温度が、前記推定温度よりも所定の第１判定値以上高い場合に、該ＥＧＲシステムが故障であると判定する。この制御信号を出している時とは、バイパス制御弁の操作用信号を出した後から次の操作用信号を出すまでの間をいう。   In the EGR system failure determination method, the measured temperature and the estimated temperature when the valve control unit outputs a control signal to the bypass control valve so that EGR gas flows to the EGR cooler side are compared, When the measured temperature is higher than the estimated temperature by a predetermined first determination value or more, it is determined that the EGR system is faulty. The time when the control signal is output refers to a period from when the operation signal for the bypass control valve is output until the next operation signal is output.

この測定温度と推定温度の比較により、ＥＧＲシステムが故障していることが分かる。つまり、ＥＧＲクーラの故障か、あるいは、ＥＧＲガスがＥＧＲクーラを通過するようにバイパス制御弁を制御しているはずであるが、ＥＧＲクーラを通過しないバイパス通路側にガスが流れているというバイパス制御弁の故障かのいずれかの可能性から、ＥＧＲクーラの故障に絞ることができる。なお、この所定の第１判定値は、予め行なわれる実験や計算などにより設定しておくことができる。   By comparing the measured temperature with the estimated temperature, it can be seen that the EGR system is malfunctioning. That is, the EGR cooler has failed or the bypass control valve should be controlled so that the EGR gas passes through the EGR cooler, but the bypass control that the gas flows to the bypass passage side that does not pass through the EGR cooler. From the possibility of any of the valve failures, it is possible to focus on EGR cooler failures. The predetermined first determination value can be set through experiments or calculations performed in advance.

上記のＥＧＲシステムの故障判定方法において、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度と、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度との測定温度差の絶対値が所定の第２判定値以下のときに、バイパス制御弁に異常があると判定する。   In the EGR system failure determination method, the valve control unit outputs a control signal to the bypass control valve so that EGR gas flows to the EGR cooler side, and the valve control unit When the absolute value of the measured temperature difference from the measured temperature when the control signal is output to the bypass control valve so that EGR gas flows to the passage side is equal to or smaller than the predetermined second determination value, there is an abnormality in the bypass control valve. Judge that there is.

この２つの制御信号を出している時の測定温度差から、バイパス制御弁が故障しているものと判定できる。つまり、ＥＧＲクーラが故障して正常に機能していない場合であっても、ＥＧＲクーラの構造上ある程度、通過するＥＧＲガスは冷却されるので、バイパス制御弁が正常に作動している場合には、ＥＧＲクーラを通過したＥＧＲガスとＥＧＲクーラが無いバイパス通路を通過したＥＧＲガスとでは、所定の第２判定値以上の温度差が生じる。そのため、２つの測定温度の差が所定の第２判定値以下である場合には、バイパス制御弁の故障に絞ることが判定できる。なお、この所定の第２判定値は、予め行なわれる実験や計算などにより設定しておくことができる。   From the measured temperature difference when the two control signals are output, it can be determined that the bypass control valve has failed. In other words, even if the EGR cooler fails and is not functioning normally, the EGR gas that passes through is cooled to some extent due to the structure of the EGR cooler, so if the bypass control valve is operating normally A temperature difference equal to or greater than a predetermined second determination value is generated between the EGR gas that has passed through the EGR cooler and the EGR gas that has passed through the bypass passage without the EGR cooler. Therefore, when the difference between the two measured temperatures is equal to or smaller than the predetermined second determination value, it can be determined that the bypass control valve is limited to failure. The predetermined second determination value can be set through experiments or calculations performed in advance.

上記のＥＧＲシステムの故障判定方法において、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度が、推定温度よりも所定の第３判定値以上低い場合に、前記バイパス制御弁に異常があると判定する。   In the failure determination method of the EGR system, the measured temperature when the valve control unit outputs a control signal to the bypass control valve so that EGR gas flows to the bypass passage side is set to a predetermined value from the estimated temperature. 3 When the value is lower than the determination value, it is determined that the bypass control valve is abnormal.

バイパス通路でＥＧＲガスが冷却される量は少ないので、推定温度よりも所定の第３判定値以上低い場合には、制御信号にもかかわらず、ＥＧＲガスはＥＧＲクーラを通過していると見なすことができるので、バイパス制御弁に異常があると判定できる。なお、この所定の第３判定値は、予め行なわれる実験や計算などにより設定しておくことができる。   Since the amount of the EGR gas cooled in the bypass passage is small, it is considered that the EGR gas passes through the EGR cooler regardless of the control signal when it is lower than the estimated temperature by a predetermined third judgment value or more. Therefore, it can be determined that there is an abnormality in the bypass control valve. The predetermined third determination value can be set through experiments or calculations performed in advance.

そして、上記の目的を達成するためのＥＧＲシステムの故障判定システムは、内燃機関の排気系から吸気系への排気の一部であるＥＧＲガスを還流させるＥＧＲ通路にＥＧＲガスを冷却するＥＧＲクーラを設置し、該ＥＧＲクーラを迂回するバイパス通路を設け、該バイパス通路に流れるＥＧＲガスの流量を調整するバイパス制御弁と、該バイパス制御弁を制御する弁制御部を備えたＥＧＲシステムに、前記バイパス通路と前記ＥＧＲ通路との合流部位よりも下流側の前記ＥＧＲ通路又は吸気系通路に配置され、ガスの温度を測定する温度センサと、車両にて検出した状態に基づいて前記温度センサが配置された位置のガスの温度を推定する温度推定部と、前記バイパス制御弁の弁開閉の制御信号と、前記温度センサで測定した測定温度と、前記温度推定部で推定した推定温度とに基づいて、該ＥＧＲシステムの故障の有無を判定する故障判定部を備えて構成される。   An EGR system failure determination system for achieving the above object includes an EGR cooler that cools EGR gas in an EGR passage that recirculates EGR gas that is part of exhaust gas from an exhaust system of an internal combustion engine to an intake system. The EGR system is provided with a bypass passage that is installed, bypasses the EGR cooler, adjusts the flow rate of EGR gas flowing through the bypass passage, and a valve control unit that controls the bypass control valve. A temperature sensor that measures the temperature of the gas is disposed in the EGR passage or the intake system passage on the downstream side of the joining portion of the passage and the EGR passage, and the temperature sensor is arranged based on a state detected by the vehicle. A temperature estimation unit that estimates the temperature of the gas at the position, a control signal for opening and closing the bypass control valve, a measured temperature measured by the temperature sensor, Serial based on the estimated temperature and estimated by the temperature estimation unit configured to include failure determination section determines the presence or absence of a failure of the EGR system.

また、上記のＥＧＲシステムの故障判定システムにおいて、前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すようにを前記バイパス制御弁に制御信号を出している時の前記測定温度と前記推定温度を比較し、前記測定温度が、前記推定温度よりも所定の第１判定値以上高い場合に、該ＥＧＲシステムが故障であると判定するように構成される。   In the EGR system failure determination system, the measurement is performed when the failure determination unit outputs a control signal to the bypass control valve so that the valve control unit causes EGR gas to flow to the EGR cooler side. The temperature is compared with the estimated temperature, and when the measured temperature is higher than the estimated temperature by a predetermined first determination value or more, the EGR system is determined to be faulty.

また、上記のＥＧＲシステムの故障判定システムにおいて、前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度と、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度との測定温度差の絶対値が所定の第２判定値以下のときに、バイパス制御弁に異常があると判定するように構成される。   Further, in the failure determination system of the EGR system, the failure determination unit may measure a temperature when the valve control unit outputs a control signal to the bypass control valve so that the EGR gas flows to the EGR cooler side. When the absolute value of the measured temperature difference from the measured temperature when the valve control unit outputs a control signal to the bypass control valve so as to flow EGR gas to the bypass passage side is equal to or smaller than a predetermined second determination value In addition, it is configured to determine that there is an abnormality in the bypass control valve.

更に、上記のＥＧＲシステムの故障判定システムにおいて、前記故障判定部が、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度が、推定温度よりも所定の第３判定値以上低い場合に、前記バイパス制御弁に異常があると判定するように構成される。   Further, in the failure determination system for the EGR system, the measured temperature when the failure determination unit outputs a control signal to the bypass control valve so that the valve control unit causes EGR gas to flow to the bypass passage side is obtained. The bypass control valve is determined to be abnormal when it is lower than the estimated temperature by a predetermined third determination value or more.

上記のＥＧＲシステムの故障判定システムにおいて、前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の前記測定温度と前記推定温度を比較し、前記測定温度が、前記推定温度よりも所定の第１判定値以上高い場合に、該ＥＧＲシステムが故障であると判定するように構成される。   In the failure determination system of the EGR system, the failure determination unit outputs the control signal to the bypass control valve so that the valve control unit causes EGR gas to flow to the EGR cooler side, and the measured temperature An estimated temperature is compared, and the EGR system is determined to be faulty when the measured temperature is higher than the estimated temperature by a predetermined first determination value or more.

上記のＥＧＲシステムの故障判定システムにおいて、前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度と、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度との測定温度差の絶対値が所定の第２判定値以下のときに、バイパス制御弁に異常があると判定するように構成される。   In the failure determination system of the EGR system, the failure determination unit is configured to output a control signal to the bypass control valve so that the valve control unit causes EGR gas to flow to the EGR cooler side; When the absolute value of the measured temperature difference from the measured temperature when the valve control unit sends a control signal to the bypass control valve so that EGR gas flows to the bypass passage side is equal to or less than a predetermined second determination value, The bypass control valve is configured to determine that there is an abnormality.

これらの構成によれば、上記したＥＧＲシステムの故障判定方法を実施することができ、同様の作用効果を奏することができる。   According to these configurations, the above-described failure determination method for the EGR system can be implemented, and the same effects can be achieved.

本発明のＥＧＲシステムの故障判定方法及びＥＧＲシステムの故障判定システムによれば、ＥＧＲクーラとバイパス通路の排気圧力損失が等しい場合でも使用でき、ＥＧＲシステムの稼働中に簡易に、不用意に耳障りな排気音の変化の発生を伴う、ＥＧＲクーラとバイパス通路との切り替え操作を行なうことなく、ＥＧＲクーラの故障の有無と、バイパス制御弁の固着による故障の有無の両方を判定することができる。   According to the failure determination method of the EGR system and the failure determination system of the EGR system of the present invention, it can be used even when the exhaust pressure loss of the EGR cooler and the bypass passage is equal, and it is easy and careless during operation of the EGR system. It is possible to determine both the presence / absence of a failure of the EGR cooler and the presence / absence of a failure due to the adhering of the bypass control valve without performing an operation of switching between the EGR cooler and the bypass passage accompanying the occurrence of a change in exhaust sound.

また、ＥＧＲシステム全体の異常を検出してから、バイパス制御弁に切り替え制御信号を出すことで、ＥＧＲクーラ側の故障であるか、バイパス制御弁側の故障であるかを検出できる。   Moreover, it is possible to detect whether the failure is on the EGR cooler side or the bypass control valve side by outputting a switching control signal to the bypass control valve after detecting an abnormality in the entire EGR system.

以下、本発明に係る実施の形態のＥＧＲシステムの故障判定方法及びＥＧＲシステムの故障判定システムについて、図面を参照しながら説明する。   Hereinafter, an EGR system failure determination method and an EGR system failure determination system according to embodiments of the present invention will be described with reference to the drawings.

図１に示すように、本発明に係わる実施の形態のＥＧＲシステムの故障判定システム１が設けられるＥＧＲシステム１０は、エンジン（内燃機関）Ｅの排気マニホールド１１ａや排気管１１ｂ等の排気系通路１１から、吸気マニホールド１２ａや吸気管１２ｂ等の吸気系通路１２へ、排気ガスＧ１の一部であるＥＧＲガスＧｅ（＝Ｇ１−Ｇ２）を還流させるＥＧＲ通路１３を設けると共に、このＥＧＲ通路１３にＥＧＲガスＧｅ１を冷却するＥＧＲクーラ１４と、このＥＧＲクーラ１４を迂回するバイパス通路１５を設けて構成される。また、このバイパス通路１５に流れるＥＧＲガスＧｅ２の流量を調整するバイパス制御弁１６と、ＥＧＲガス量全体Ｇｅ（＝Ｇｅ１＋Ｇｅ２）を制御するＥＧＲ弁１７と、このバイパス制御弁１６とＥＧＲ弁１７を制御する弁制御部３１を備えて構成される。   As shown in FIG. 1, an EGR system 10 provided with an EGR system failure determination system 1 according to an embodiment of the present invention includes an exhaust system passage 11 such as an exhaust manifold 11 a and an exhaust pipe 11 b of an engine (internal combustion engine) E. The EGR passage 13 for returning EGR gas Ge (= G1-G2), which is a part of the exhaust gas G1, is provided to the intake system passage 12 such as the intake manifold 12a and the intake pipe 12b. An EGR cooler 14 that cools the gas Ge1 and a bypass passage 15 that bypasses the EGR cooler 14 are provided. Further, a bypass control valve 16 for adjusting the flow rate of the EGR gas Ge2 flowing through the bypass passage 15, an EGR valve 17 for controlling the entire EGR gas amount Ge (= Ge1 + Ge2), and the bypass control valve 16 and the EGR valve 17 are controlled. The valve control unit 31 is configured.

このＥＧＲ弁１７は、低温のＥＧＲガスＧｅが通過するように、バイパス通路１５とＥＧＲ通路１３との合流部位（図１の構成ではバイパス制御弁１６の位置）１３ｂよりも下流側のＥＧＲ通路１３に設けられる。また、バイパス制御弁１６は、図１の実施の形態では、ＥＧＲクーラ１４よりも下流側のＥＧＲ通路１３とバイパス通路１５との合流部位１３ｂに配置しているが、ＥＧＲクーラ１４よりも上流側のＥＧＲ通路１３とバイパス通路１５との分岐部位１３ａでも良く、また、バイパス通路１５部分でも、ＥＧＲ通路１３におけるバイパス通路１５の分岐部位１３ａと合流部位１３ｂの間のＥＧＲクーラ１４の前後のＥＧＲ通路１３部分であってもよい。そして、弁制御部３１は、エンジンＥ全体を制御するエンジン制御装置（ＥＣＵ）３０に設けられる。   The EGR valve 17 has an EGR passage 13 on the downstream side of a joining portion (position of the bypass control valve 16 in the configuration of FIG. 1) 13b between the bypass passage 15 and the EGR passage 13 so that the low-temperature EGR gas Ge passes therethrough. Is provided. Further, in the embodiment of FIG. 1, the bypass control valve 16 is disposed in the joining portion 13 b of the EGR passage 13 and the bypass passage 15 downstream of the EGR cooler 14, but is upstream of the EGR cooler 14. The EGR passage 13 and the bypass passage 15 of the EGR passage 13 may be a branch portion 13a, or the EGR passage before and after the EGR cooler 14 between the branch portion 13a of the bypass passage 15 and the merge portion 13b in the EGR passage 13 may be used. 13 parts may be sufficient. And the valve control part 31 is provided in the engine control apparatus (ECU) 30 which controls the engine E whole.

そして、ＥＧＲシステムの故障判定システム１は、このＥＧＲシステム１０において、バイパス通路１５とＥＧＲ通路１３との合流部位１３ｂよりも下流側のＥＧＲ通路１３又は吸気系通路１２にＥＧＲガスの温度を測定する温度センサ１８（又は（１８））が配置される。更に、この温度センサ１８の検出値から測定温度Ｔｍを求める温度測定部２１と、エンジンＥを搭載した車両にて検出した状態に基づいて温度センサ１８が配置された位置のガスＧｅ（又は温度センサ（１８）が配置された位置の新気（吸入空気）ＡとＥＧＲガスＧｅが混合した混合ガスＧｍ（＝Ａ＋Ｇｅ））の温度を推定する温度推定部２２と、バイパス制御弁１６の弁開閉の制御信号と、温度センサ１８で測定し温度測定部２１で得られた測定温度Ｔｍと、温度推定部２２で推定した推定温度Ｔｓとに基づいて、ＥＧＲシステム１０の故障の有無を判定する故障判定部２３を備えて構成される。   The failure determination system 1 of the EGR system measures the temperature of the EGR gas in the EGR passage 13 or the intake system passage 12 downstream of the joining portion 13b of the bypass passage 15 and the EGR passage 13 in the EGR system 10. A temperature sensor 18 (or (18)) is arranged. Further, a temperature measurement unit 21 for obtaining a measurement temperature Tm from a detection value of the temperature sensor 18 and a gas Ge (or temperature sensor) at a position where the temperature sensor 18 is arranged based on a state detected by a vehicle equipped with the engine E. A temperature estimation unit 22 that estimates the temperature of the mixed gas Gm (= A + Ge) in which fresh air (intake air) A and EGR gas Ge are mixed at the position where (18) is disposed, and opening and closing of the bypass control valve 16 A failure determination that determines the presence or absence of a failure in the EGR system 10 based on the control signal, the measured temperature Tm measured by the temperature sensor 18 and obtained by the temperature measurement unit 21, and the estimated temperature Ts estimated by the temperature estimation unit 22 The unit 23 is provided.

これらの温度測定部２１と温度推定部２２と故障判定部２３は、通常は、図１に示すように、エンジン制御装置（ＥＣＵ）３０内に設けるが、エンジン制御装置（ＥＣＵ）３０内の弁制御部３１の制御信号と温度センサ１８の温度検出信号とを入力できる故障判定装置に設けてもよい。この故障判定装置をエンジン制御装置３０と別に設けることで、既存の車両にも容易に追加して設けることができる。また、車両点検時の故障診断時だけ接続して設けて、故障診断後は取り外すことも可能となる。   These temperature measurement unit 21, temperature estimation unit 22, and failure determination unit 23 are normally provided in an engine control unit (ECU) 30 as shown in FIG. 1, but valves in the engine control unit (ECU) 30 are provided. You may provide in the failure determination apparatus which can input the control signal of the control part 31, and the temperature detection signal of the temperature sensor 18. FIG. By providing this failure determination device separately from the engine control device 30, it can be easily added to an existing vehicle. Further, it is possible to connect only at the time of failure diagnosis at the time of vehicle inspection and to remove it after failure diagnosis.

次に、上記の故障判定部２３における故障判定方法について説明する。この故障判定は、図２及び図３に例示された制御フローに従って実行される。この図２及び図３の制御フローは、ＥＧＲシステムの故障判定が必要な時に、上級の制御フロー、例えば、エンジンの制御を行うメインの制御フロー等から呼ばれて実行され、実行後は、リターンするものとして示してある。   Next, a failure determination method in the failure determination unit 23 will be described. This failure determination is executed according to the control flow illustrated in FIGS. The control flow in FIGS. 2 and 3 is called and executed from an advanced control flow, for example, a main control flow for controlling the engine, when failure determination of the EGR system is necessary. It is shown as something to do.

エンジンのキーがオン（ＯＮ）されて、エンジンが運転開始されると、エンジンの制御プログラムから必要に応じて呼ばれるか、エンジン全体の制御から切り離された故障判定装置から呼ばれるかして、この図２の制御フローがスタートする。このスタートにより、スッテプＳ１１で、バイパス制御弁１６への弁制御部３１の制御信号をチェックする。つまり、この制御信号が、ＥＧＲクーラ１４側にＥＧＲガスＧｅを流す制御信号であるか、否かをチェックする。   When the engine key is turned on (ON) and the engine is started, it is called as necessary from the engine control program or from a failure determination device separated from the overall engine control. 2 control flow starts. By this start, the control signal of the valve control unit 31 to the bypass control valve 16 is checked at step S11. That is, it is checked whether or not this control signal is a control signal for flowing the EGR gas Ge to the EGR cooler 14 side.

このステップＳ１１のバイパス制御弁１６への制御信号チェックで、制御信号がＥＧＲクーラ１４側にＥＧＲガスＧｅを流す制御信号であれば（ＹＥＳ）、ステップＳ１２で温度センサ１８による測定温度Ｔｍ１を入力し、次のステップＳ１３で、推定温度Ｔｓを算出する。この推定温度Ｔｓは、外気温度、排気温度、吸気圧、ＥＧＲ弁開度等を引数とした関数で算出される。この関数は予め実験や計算等で求めておき、記憶しておく。なお、関数の代りにマップデータを利用して算出するようにしてもよい。   In the control signal check to the bypass control valve 16 in step S11, if the control signal is a control signal for flowing EGR gas Ge to the EGR cooler 14 side (YES), the measured temperature Tm1 by the temperature sensor 18 is input in step S12. In the next step S13, the estimated temperature Ts is calculated. This estimated temperature Ts is calculated by a function having the outside air temperature, the exhaust gas temperature, the intake pressure, the EGR valve opening degree and the like as arguments. This function is obtained in advance by experiments or calculations and stored. The calculation may be performed using map data instead of the function.

この推定温度Ｔｓの算出について、例えば、推定吸気温度の算出の場合には、例えば、エンジン始動時の外気温度、吸入温度、及び水温等から、吸気温度のベース温度を算出し、それに対して、エンジン回転数と燃料噴射量と経過時間から、温度上昇分を算出する。更に、排気温度、バイパス制御弁１６のＯＮ，ＯＦＦ，車速、エンジン温度（水温、燃焼温度）、外気温度、室内用ヒータなどのＯＮ，ＯＦＦおよび経過時間情報から、温度下降分を算出し、「ベース温度＋温度上昇分＋温度下降分」より推定温度Ｔｓを算出する。   Regarding the calculation of the estimated temperature Ts, for example, in the case of calculating the estimated intake air temperature, for example, the base temperature of the intake air temperature is calculated from the outside air temperature, the intake temperature, the water temperature, etc. at the time of starting the engine, The temperature rise is calculated from the engine speed, the fuel injection amount, and the elapsed time. Furthermore, the temperature decrease is calculated from the exhaust temperature, ON / OFF of the bypass control valve 16, vehicle speed, engine temperature (water temperature, combustion temperature), outside air temperature, ON / OFF of the indoor heater, etc. and elapsed time information. The estimated temperature Ts is calculated from “base temperature + temperature rise + temperature drop”.

次のステップＳ１４で、測定温度Ｔｍ１のチェックを行なう。つまり、この測定温度Ｔｍ１と、推定温度Ｔｓに所定の第１判定値Ｔｃ１を加えた判定値（Ｔｓ＋Ｔｃ１）とを比較する。この比較のステップＳ１４で、測定温度Ｔｍ１が、判定値（Ｔｓ＋Ｔｃ１）未満の場合（ＮＯ）には、ステップＳ１５にいく。ステップＳ１５では、ＥＧＲシステム１０のＥＧＲクーリングシステムが正常であると判定し、故障判定を終了してリターンする。なお、再度故障判定が必要になれば、この図２の制御フローが呼ばれてスタートする。   In the next step S14, the measurement temperature Tm1 is checked. That is, the measured temperature Tm1 is compared with a determination value (Ts + Tc1) obtained by adding a predetermined first determination value Tc1 to the estimated temperature Ts. If the measured temperature Tm1 is less than the determination value (Ts + Tc1) in step S14 of this comparison (NO), the process goes to step S15. In step S15, it is determined that the EGR cooling system of the EGR system 10 is normal, the failure determination is terminated, and the process returns. If the failure determination is necessary again, the control flow of FIG. 2 is called and started.

このステップＳ１４の比較で、測定温度Ｔｍ１が、判定値（Ｔｓ＋Ｔｃ１）以上の場合（ＹＥＳ）には、ステップＳ１６にいく。ステップＳ１６では、ＥＧＲシステム１０のＥＧＲシステムが、より詳細にはＥＧＲクーリングシステムが故障であると判定し、ＥＧＲクーリングシステム異常時処理を行なう。つまり、エラーコード（バルブ異常時の診断コード）を出力したり、異常発生時の各種データの保存等バックアップ処理を行なったり、排ガス処理能力が低下するので出力制限を行い警告ランプを表示したりする。そして、次のステップＳ２０の異常部分の判定に行く。   If the measured temperature Tm1 is equal to or higher than the determination value (Ts + Tc1) in the comparison in step S14 (YES), the process goes to step S16. In step S16, the EGR system of the EGR system 10 determines in more detail that the EGR cooling system is out of order, and performs processing when the EGR cooling system is abnormal. In other words, an error code (diagnostic code at the time of valve abnormality) is output, backup processing such as saving of various data at the time of abnormality occurs, exhaust gas processing capacity decreases, output is limited and a warning lamp is displayed . Then, the process goes to the determination of the abnormal part in the next step S20.

このステップＳ２０では、図３の制御フローに示すように、最初のステップＳ２１で、測定温度Ｔｍ１を入力する。この測定温度Ｔｍ１は、バイパス制御弁１６へＥＧＲクーラ１４側にＥＧＲガスＧｅを流すように弁制御部３１が制御信号を出している時の測定温度となる。次のステップＳ２２で、弁制御部３１からバイパス制御弁１６へバイパス通路１５側にＥＧＲガスを流すように制御信号を出す。つまり、制御信号を切り替える。そして、次のステップＳ２３で測定温度Ｔｍ２を入力する。この測定温度Ｔｍ２は、バイパス制御弁１６へバイパス通路１５側にＥＧＲガスＧｅを流すように弁制御部３１が制御信号を出している時の測定温度となる。   In step S20, as shown in the control flow of FIG. 3, the measured temperature Tm1 is input in the first step S21. The measured temperature Tm1 is a measured temperature when the valve control unit 31 is outputting a control signal so that the EGR gas Ge flows through the bypass control valve 16 to the EGR cooler 14 side. In the next step S22, a control signal is issued so that EGR gas flows from the valve control unit 31 to the bypass control valve 16 to the bypass passage 15 side. That is, the control signal is switched. In step S23, the measurement temperature Tm2 is input. The measured temperature Tm2 is a measured temperature when the valve control unit 31 is outputting a control signal so that the EGR gas Ge flows to the bypass control valve 16 on the bypass passage 15 side.

次のステップＳ２４で、これらの測定温度Ｔｍ１，Ｔｍ２の差（Ｔｍ２−Ｔｍ１）の絶対値と所定の第２判定値Ｔｃ２とを比較する。このステップＳ２４の比較で、測定温度差（Ｔｍ２−Ｔｍ１）の絶対値（｜Ｔｍ２−Ｔｍ１｜）が所定の第２判定値Ｔｃ２以下であれば（ＹＥＳ）、ステップＳ２５に行き、バイパス制御弁１６が故障していると判定し、バイパス制御弁の異常時処理を行なって、ステップＳ２０を終了する。この異常時処理では、バイパス制御弁１６への通電を停止したり、スタック（固着）が直ったときに復帰できるように、定期的に通電して診断を行なう等する。   In the next step S24, the absolute value of the difference (Tm2−Tm1) between these measured temperatures Tm1 and Tm2 is compared with a predetermined second determination value Tc2. If the absolute value (| Tm2-Tm1 |) of the measured temperature difference (Tm2-Tm1) is equal to or smaller than the predetermined second determination value Tc2 (YES) in step S24, the process goes to step S25 and the bypass control valve 16 Is determined to be malfunctioning, the process when the bypass control valve is abnormal is performed, and step S20 is terminated. In this abnormal process, the energization to the bypass control valve 16 is stopped, or the energization is periodically performed for diagnosis so that the return can be made when the stack (fixation) is corrected.

また、このステップＳ２４の比較で、測定温度差（Ｔｍ２−Ｔｍ１）の絶対値（｜Ｔｍ２−Ｔｍ１｜）が所定の第２判定値Ｔｃ２以上であれば（ＮＯ）、ステップＳ２６に行き、バイパス制御バルブ１６は故障していないと判定し、つまり、バイパス制御弁１６以外の部分（例えば、ＥＧＲクーラ１４）が故障していると判定し、バイパス制御弁の正常時処理を行なって、ステップＳ２０を終了する。この正常時処理では、バルブ異常時から正常時になった場合には、正常動作させたり、バルブ異常時の診断コードを消去したりする。ステップＳ２０が終了すると、図２の制御フローに戻って、故障判定を終了してリターンする。なお、再度故障判定が必要になれば、この図２の制御フローが呼ばれてスタートする。   If the absolute value (| Tm2−Tm1 |) of the measured temperature difference (Tm2−Tm1) is greater than or equal to the predetermined second determination value Tc2 (NO) in the comparison in step S24, the process goes to step S26 to perform bypass control. It is determined that the valve 16 has not failed, that is, it is determined that a portion other than the bypass control valve 16 (for example, the EGR cooler 14) has failed, the normal processing of the bypass control valve is performed, and step S20 is performed. finish. In this normal processing, when the valve is abnormal and normal, the normal operation is performed or the diagnostic code at the time of valve abnormality is deleted. When step S20 ends, the process returns to the control flow of FIG. 2, ends the failure determination, and returns. If the failure determination is necessary again, the control flow of FIG. 2 is called and started.

ステップＳ１１のバイパス制御弁１６への制御信号チェックで、制御信号がＥＧＲクーラ１４側にＥＧＲガスＧｅを流す制御信号でなければ（ＮＯ）、ステップＳ３１で温度センサ１８による測定温度Ｔｍ２を入力し、次のステップＳ３２で、推定温度Ｔｓを算出する。この推定温度Ｔｓは、ステップＳ１３と同様に、外気温度、排気温度、吸気圧、ＥＧＲ弁開度等を引数とした関数で算出される。   In the control signal check to the bypass control valve 16 in step S11, if the control signal is not a control signal for flowing the EGR gas Ge to the EGR cooler 14 side (NO), the measured temperature Tm2 by the temperature sensor 18 is input in step S31, In the next step S32, an estimated temperature Ts is calculated. This estimated temperature Ts is calculated by a function with the outside air temperature, the exhaust gas temperature, the intake pressure, the EGR valve opening, etc. as arguments, as in step S13.

次のステップＳ３３で、測定温度Ｔｍ２のチェックを行なう。つまり、この測定温度Ｔｍ２と、推定温度Ｔｓに所定の第３判定値Ｔｃ３を差し引いた判定値（ＴｓーＴｃ３）とを比較する。   In the next step S33, the measurement temperature Tm2 is checked. That is, the measured temperature Tm2 is compared with a determination value (Ts−Tc3) obtained by subtracting a predetermined third determination value Tc3 from the estimated temperature Ts.

この比較のステップＳ３３で、測定温度Ｔｍ２が、判定値（Ｔｓ−Ｔｃ３）以上の場合（ＹＥＳ）には、ステップＳ１５に行く。ステップＳ１５では、ＥＧＲシステム１０のＥＧＲクーリングシステムが正常であると判定し、故障判定を終了してリターンする。なお、再度故障判定が必要になれば、この図２の制御フローが呼ばれてスタートする。   In step S33 of this comparison, if the measured temperature Tm2 is equal to or higher than the determination value (Ts−Tc3) (YES), the process goes to step S15. In step S15, it is determined that the EGR cooling system of the EGR system 10 is normal, the failure determination is terminated, and the process returns. If the failure determination is necessary again, the control flow of FIG. 2 is called and started.

このステップＳ３３の比較で、測定温度Ｔｍ２が、判定値（Ｔｓ−Ｔｃ３）未満の場合（ＮＯ）には、ステップＳ３４に行く。ステップＳ３４では、バイパス制御弁１６が故障であると判定し、バイパス制御弁の異常時処理を行なう。つまり、エラーコードを出力したり、バックアップ処理を行なったりする。そして、故障判定を終了してリターンする。なお、再度故障判定が必要になれば、この図２の制御フローが呼ばれてスタートする。   If the measured temperature Tm2 is lower than the determination value (Ts−Tc3) (NO) in step S33, the process goes to step S34. In step S34, it is determined that the bypass control valve 16 is in failure, and processing is performed when the bypass control valve is abnormal. In other words, an error code is output or backup processing is performed. Then, the failure determination is finished and the process returns. If the failure determination is necessary again, the control flow of FIG. 2 is called and started.

このＥＧＲシステムの故障判定方法によれば、弁制御部３１がＥＧＲクーラ１４側にＥＧＲガスを流すようにバイパス制御弁１６に制御信号を出している時の測定温度Ｔｍ１と推定温度Ｔｓを比較し、測定温度Ｔｍ１が、推定温度Ｔｓよりも所定の第１判定値Ｔｃ１以上高い場合に、ＥＧＲシステムが故障であると判定する（Ｓ１６）。   According to this failure determination method for the EGR system, the measured temperature Tm1 and the estimated temperature Ts when the valve control unit 31 outputs a control signal to the bypass control valve 16 so that EGR gas flows to the EGR cooler 14 side are compared. When the measured temperature Tm1 is higher than the estimated temperature Ts by a predetermined first determination value Tc1, it is determined that the EGR system is malfunctioning (S16).

また、弁制御部３１がＥＧＲクーラ１４側にＥＧＲガスを流すようにバイパス制御弁１６に制御信号を出している時の測定温度Ｔｍ１と、弁制御部３１がバイパス通路１５側にＥＧＲガスを流すようにバイパス制御弁１６に制御信号を出している時の測定温度Ｔｍ２との測定温度差の絶対値（｜Ｔｍ２−Ｔｍ１｜）が所定の第２判定値Ｔｃ２以下のときに、バイパス制御弁に異常があると判定する（Ｓ２５）。   Further, the measured temperature Tm1 when the valve control unit 31 outputs a control signal to the bypass control valve 16 so that EGR gas flows to the EGR cooler 14 side, and the valve control unit 31 flows EGR gas to the bypass passage 15 side. When the absolute value (| Tm2−Tm1 |) of the measured temperature difference from the measured temperature Tm2 when the control signal is output to the bypass control valve 16 is equal to or smaller than the predetermined second determination value Tc2, the bypass control valve It is determined that there is an abnormality (S25).

更に、弁制御部３１がバイパス通路１５側にＥＧＲガスを流すようにバイパス制御弁１６に制御信号を出している時の測定温度Ｔｍ２が、推定温度Ｔｓよりも所定の第３判定値Ｔｃ３以上低い場合に、バイパス制御弁１６に異常があると判定する（Ｓ３４）。   Further, the measured temperature Tm2 when the valve control unit 31 outputs a control signal to the bypass control valve 16 so that EGR gas flows to the bypass passage 15 side is lower than the estimated temperature Ts by a predetermined third determination value Tc3 or more. In this case, it is determined that the bypass control valve 16 is abnormal (S34).

従って、本発明のＥＧＲシステムの故障判定方法及びＥＧＲシステムの故障判定システム１によれば、ＥＧＲクーラ１４とバイパス通路１５の排気圧力損失が等しい場合でも使用でき、ＥＧＲシステム１０の稼働中に簡易に、不用意に耳障りな排気音の変化の発生を伴う、ＥＧＲクーラ１４とバイパス通路１５との切り替え操作を行なうことなく、ＥＧＲクーラ１４の故障の有無と、バイパス制御弁１６の固着による故障の有無の両方を判定することができる。   Therefore, according to the failure determination method of the EGR system and the failure determination system 1 of the EGR system of the present invention, the EGR system can be used even when the exhaust gas pressure loss in the EGR cooler 14 and the bypass passage 15 are equal, and can be easily used while the EGR system 10 is in operation. Without the switching operation between the EGR cooler 14 and the bypass passage 15, which is accompanied by the occurrence of an unpleasant exhaust noise change, the presence or absence of the EGR cooler 14 and the failure due to the adhering bypass control valve 16 Both can be determined.

また、ＥＧＲシステム１０全体の異常を検出してから、バイパス制御弁１６に切り替え制御信号を出すことで、ＥＧＲクーラ１４側の故障であるか、バイパス制御弁１６側の故障であるかを検出できる。つまり、ＥＧＲシステム１０の故障判断において、バイパス制御弁１６の故障と他に起因する故障とを切り分けることができる。   In addition, it is possible to detect whether the failure is on the EGR cooler 14 side or the bypass control valve 16 side by outputting a switching control signal to the bypass control valve 16 after detecting an abnormality in the entire EGR system 10. . That is, in the failure determination of the EGR system 10, the failure of the bypass control valve 16 and the failure caused by others can be separated.

本発明に係る実施の形態のＥＧＲシステム及びＥＧＲシステムの故障判定システムの構成を示す図である。It is a figure which shows the structure of the failure determination system of the EGR system and EGR system of embodiment which concerns on this invention. 本発明に係る実施の形態のＥＧＲシステムの故障判定方法の制御フローの一例を示す図である。It is a figure which shows an example of the control flow of the failure determination method of the EGR system of embodiment which concerns on this invention. 図２の異常部分の判定の制御フローを示す図である。It is a figure which shows the control flow of determination of the abnormal part of FIG.

符号の説明Explanation of symbols

Ｅ エンジン
１ ＥＧＲシステムの故障判定システム
１０ ＥＧＲシステム
１１ 排気系通路
１２ 吸気系通路
１３ ＥＧＲ通路
１３ａ 分岐部位
１３ｂ 合流部位
１４ ＥＧＲクーラ
１５ バイパス通路
１６ バイパス制御弁
１７ ＥＧＲ弁
１８ 温度センサ
２１ 温度測定部
２２ 温度推定部
２３ 故障判定部
３０ エンジン制御装置（ＥＣＵ）
３１ 弁制御部
Ａ 新気（吸入空気）
Ｇ１，Ｇ２ 排気ガス
Ｇｅ，Ｇｅ１，Ｇｅ２ ＥＧＲガス
Ｇｍ 混合ガス
Ｔｍ，Ｔｍ１．Ｔｍ２ 測定温度
Ｔｓ 推定温度
Ｔｃ１ 所定の第１判定値
Ｔｃ２ 所定の第２判定値
Ｔｃ３ 所定の第３判定値 E engine 1 EGR system failure determination system 10 EGR system 11 exhaust system passage 12 intake system passage 13 EGR passage 13a branching portion 13b confluence portion 14 EGR cooler 15 bypass passage 16 bypass control valve 17 EGR valve 18 temperature sensor 21 temperature measuring unit 22 Temperature estimation unit 23 Failure determination unit 30 Engine control unit (ECU)
31 Valve control part A Fresh air (intake air)
G1, G2 exhaust gas Ge, Ge1, Ge2 EGR gas Gm mixed gas Tm, Tm1. Tm2 Measurement temperature Ts Estimated temperature Tc1 Predetermined first determination value Tc2 Predetermined second determination value Tc3 Predetermined third determination value

Claims (8)

内燃機関の排気系から吸気系への排気の一部であるＥＧＲガスを還流させるＥＧＲ通路にＥＧＲガスを冷却するＥＧＲクーラを設置し、該ＥＧＲクーラを迂回するバイパス通路を設け、該バイパス通路に流れるＥＧＲガスの流量を調整するバイパス制御弁と、該バイパス制御弁を制御する弁制御部を備えたＥＧＲシステムの故障判定方法において、
前記バイパス通路と前記ＥＧＲ通路との合流部位よりも下流側の前記ＥＧＲ通路又は吸気系通路のガスの温度を測定すると共に、車両にて検出した状態に基づいて前記ガスの温度を測定する位置のガスの温度を推定し、
前記バイパス制御弁の弁開閉の制御信号と、前記測定温度と、前記推定温度とに基づいて、該ＥＧＲシステムの故障の有無を判定することを特徴とするＥＧＲシステムの故障判定方法。 An EGR cooler that cools the EGR gas is installed in an EGR passage that recirculates EGR gas that is part of the exhaust gas from the exhaust system of the internal combustion engine to the intake system, and a bypass passage that bypasses the EGR cooler is provided. In a failure determination method for an EGR system comprising a bypass control valve for adjusting the flow rate of flowing EGR gas and a valve control unit for controlling the bypass control valve,
The temperature of the gas in the EGR passage or the intake system passage on the downstream side of the joining portion of the bypass passage and the EGR passage is measured, and the gas temperature is measured based on the state detected by the vehicle. Estimate the temperature of the gas,
A failure determination method for an EGR system, wherein the presence or absence of a failure in the EGR system is determined based on a control signal for opening and closing the bypass control valve, the measured temperature, and the estimated temperature. 前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の前記測定温度と前記推定温度を比較し、前記測定温度が、前記推定温度よりも所定の第１判定値以上高い場合に、該ＥＧＲシステムが故障であると判定することを特徴とする請求項１記載のＥＧＲシステムの故障判定方法。   The measured temperature is compared with the estimated temperature when the valve control unit sends a control signal to the bypass control valve so that EGR gas flows to the EGR cooler side, and the measured temperature is higher than the estimated temperature. 2. The failure determination method for an EGR system according to claim 1, wherein when the EGR system is higher than a predetermined first determination value, it is determined that the EGR system is defective. 前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度と、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度との測定温度差の絶対値が所定の第２判定値以下のときに、バイパス制御弁に異常があると判定することを特徴とする請求項１又は２記載のＥＧＲシステムの故障判定方法。   The measured temperature when the valve control unit sends a control signal to the bypass control valve so that EGR gas flows to the EGR cooler side, and the valve control unit causes the EGR gas to flow to the bypass passage side. It is determined that there is an abnormality in the bypass control valve when the absolute value of the measured temperature difference from the measured temperature when the control signal is output to the bypass control valve is equal to or smaller than a predetermined second determination value. Item 3. An EGR system failure determination method according to Item 1 or 2. 前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度が、推定温度よりも所定の第３判定値以上低い場合に、前記バイパス制御弁に異常があると判定することを特徴とする請求項１、２又は３記載のＥＧＲシステムの故障判定方法。   When the measured temperature when the valve control unit outputs a control signal to the bypass control valve so that EGR gas flows to the bypass passage side is lower than the estimated temperature by a predetermined third determination value or more, the bypass 4. The failure determination method for an EGR system according to claim 1, wherein the control valve is determined to be abnormal. 内燃機関の排気系から吸気系への排気の一部であるＥＧＲガスを還流させるＥＧＲ通路にＥＧＲガスを冷却するＥＧＲクーラを設置し、該ＥＧＲクーラを迂回するバイパス通路を設け、該バイパス通路に流れるＥＧＲガスの流量を調整するバイパス制御弁と、該バイパス制御弁を制御する弁制御部を備えたＥＧＲシステムに、
前記バイパス通路と前記ＥＧＲ通路との合流部位よりも下流側の前記ＥＧＲ通路又は吸気系通路に配置され、ガスの温度を測定する温度センサと、
車両にて検出した状態に基づいて前記温度センサが配置された位置のガスの温度を推定する温度推定部と、
前記バイパス制御弁の弁開閉の制御信号と、前記温度センサで測定した測定温度と、前記温度推定部で推定した推定温度とに基づいて、該ＥＧＲシステムの故障の有無を判定する故障判定部を備えたことを特徴とするＥＧＲシステムの故障判定システム。 An EGR cooler that cools the EGR gas is installed in an EGR passage that recirculates EGR gas that is part of the exhaust gas from the exhaust system of the internal combustion engine to the intake system, and a bypass passage that bypasses the EGR cooler is provided. An EGR system including a bypass control valve that adjusts the flow rate of flowing EGR gas and a valve control unit that controls the bypass control valve,
A temperature sensor that is disposed in the EGR passage or the intake system passage on the downstream side of the joining portion of the bypass passage and the EGR passage, and measures the temperature of the gas;
A temperature estimation unit that estimates the temperature of the gas at the position where the temperature sensor is arranged based on the state detected by the vehicle;
A failure determination unit that determines whether or not there is a failure in the EGR system based on a control signal for opening and closing the bypass control valve, a measured temperature measured by the temperature sensor, and an estimated temperature estimated by the temperature estimation unit; A failure determination system for an EGR system, comprising: 前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すようにを前記バイパス制御弁に制御信号を出している時の前記測定温度と前記推定温度を比較し、前記測定温度が、前記推定温度よりも所定の第１判定値以上高い場合に、該ＥＧＲシステムが故障であると判定することを特徴とする請求項５記載のＥＧＲシステムの故障判定システム。   The failure determination unit compares the measured temperature with the estimated temperature when the control signal is output to the bypass control valve so that the valve control unit causes EGR gas to flow to the EGR cooler side, and the measured temperature 6. The EGR system failure determination system according to claim 5, wherein the EGR system determines that the EGR system is in failure when the temperature is higher than the estimated temperature by a predetermined first determination value or more. 前記故障判定部が、前記弁制御部が前記ＥＧＲクーラ側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度と、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度との測定温度差の絶対値が所定の第２判定値以下のときに、バイパス制御弁に異常があると判定することを特徴とする請求項５又は６記載のＥＧＲシステムの故障判定システム。   The failure determination unit has a measured temperature when the valve control unit outputs a control signal to the bypass control valve so that EGR gas flows to the EGR cooler side, and the valve control unit performs EGR on the bypass passage side. When the absolute value of the measured temperature difference from the measured temperature when the control signal is output to the bypass control valve so as to flow gas is equal to or smaller than a predetermined second determination value, it is determined that the bypass control valve is abnormal. The failure determination system for an EGR system according to claim 5 or 6. 前記故障判定部が、前記弁制御部が前記バイパス通路側にＥＧＲガスを流すように前記バイパス制御弁に制御信号を出している時の測定温度が、推定温度よりも所定の第３判定値以上低い場合に、前記バイパス制御弁に異常があると判定することを特徴とする請求項５、６又は７記載のＥＧＲシステムの故障判定システム。   The measured temperature when the failure determination unit outputs a control signal to the bypass control valve so that the valve control unit causes EGR gas to flow to the bypass passage side is a predetermined third determination value or more than the estimated temperature. 8. The failure determination system for an EGR system according to claim 5, 6 or 7, wherein when it is low, it is determined that the bypass control valve is abnormal.
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