JP6369291B2 - Oxygen concentration detection device failure detection system and oxygen concentration detection device failure detection method - Google Patents
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- 238000001514 detection method Methods 0.000 title claims description 206
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims description 192
- 239000001301 oxygen Substances 0.000 title claims description 192
- 229910052760 oxygen Inorganic materials 0.000 title claims description 192
- 239000007789 gas Substances 0.000 claims description 66
- 238000002485 combustion reaction Methods 0.000 claims description 20
- 238000003745 diagnosis Methods 0.000 description 15
- 238000000034 method Methods 0.000 description 9
- 230000004043 responsiveness Effects 0.000 description 7
- 230000035484 reaction time Effects 0.000 description 5
- 230000004044 response Effects 0.000 description 5
- 230000005856 abnormality Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 230000000994 depressogenic effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000000881 depressing effect Effects 0.000 description 1
- 230000027734 detection of oxygen Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Description
本発明は、内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障検出の誤診断を防止して、その故障検出を容易とすることができる酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法に関する。 The present invention relates to a failure detection of an oxygen concentration detection device capable of preventing erroneous diagnosis of failure detection of an oxygen concentration detection device for detecting the concentration of oxygen contained in exhaust gas of an internal combustion engine and facilitating the failure detection. The present invention relates to a fault detection method for a system and an oxygen concentration detection apparatus.
一般的に、ディーゼルエンジン等の内燃機関では、その排気ガスに含まれる酸素の濃度を検出する酸素濃度センサ（Ｏ2センサ）やＮＯｘ濃度センサにおける酸素（Ｏ2）信号の検出等の酸素濃度検出装置が使用されている。 In general, in an internal combustion engine such as a diesel engine, oxygen concentration detection such as detection of an oxygen (O 2 ) signal in an oxygen concentration sensor (O 2 sensor) that detects the concentration of oxygen contained in the exhaust gas or a NOx concentration sensor. The device is in use.
従来技術の酸素濃度検出装置の故障診断の一つの方法に、内燃機関を搭載した車両のアクセルＯＮからアクセルＯＦＦしたときの排気ガス中の酸素濃度が低い状態から、アクセルＯＦＦで燃料噴射が停止し、酸素濃度が外気の酸素濃度（約２１％）になるまでの応答時間を測定することで行われている。つまり、このアクセルがＯＮからＯＦＦに切り替わったときから、酸素濃度検出装置の検出値の変化が約２１％の値になるまでの経過時間が予め設定した判定時間よりも長い場合に、故障と診断している。 One method for diagnosing faults in prior art oxygen concentration detection devices is that fuel injection stops when the accelerator is turned off from the low oxygen concentration in the exhaust gas when the accelerator is turned on from the accelerator on a vehicle equipped with an internal combustion engine. The measurement is performed by measuring the response time until the oxygen concentration reaches the oxygen concentration (about 21%) of the outside air. In other words, when the elapsed time from when the accelerator is switched from ON to OFF until the change in the detected value of the oxygen concentration detecting device reaches a value of about 21% is longer than a predetermined determination time, a diagnosis is made. doing.
しかしながら、酸素濃度検出装置は、センサ素子を挿入するための穴を開けたカバーでセンサ素子を覆う構造をしているため、このセンサの応答性はカバーの内と外との間のガスの交換性に大きく左右される。そして、このガスの交換性は、センサ周辺におけるガスの流速に依存し、このガスの流速はガスの流量によって変化するので、センサの応答性は、ガスの流量に依存し、ガスの流量が大きい場合はガスの交換性が良く、センサの応答性が高くなるのに対し、ガスの流量が小さい場合は、排気ガスの交換性が悪く、センサの応答性が低くなる。 However, since the oxygen concentration detection device has a structure in which the sensor element is covered with a cover with a hole for inserting the sensor element, the responsiveness of the sensor is exchange of gas between the inside and outside of the cover. It depends greatly on sex. The gas exchange property depends on the gas flow rate around the sensor, and the gas flow rate varies depending on the gas flow rate. Therefore, the sensor response depends on the gas flow rate and the gas flow rate is large. In this case, the gas exchange is good and the sensor response is high. On the other hand, when the gas flow rate is small, the exhaust gas exchange is bad and the sensor response is low.
つまり、酸素に対する酸素濃度検出装置の応答性（レスポンス性）は、酸素濃度検出装置を通過する排気ガスの流量に応じて大きく異なり、検出値の時間的変化は排気ガスの流量に応じて大きく異なっている。そのため、アクセルＯＮからアクセルＯＦＦの間の排気ガスの流量が異なると、センサの応答性が異なってくる。排気ガスの流量の変化が大きい場合は酸素濃度の変化も大きくなるので、異常と正常の区別が容易であるが、排気ガスの流量の変化が小さい場合は酸素濃度の変化も小さくなるので、異常と正常の区別が難しい。 In other words, the responsiveness (responsiveness) of the oxygen concentration detection device to oxygen varies greatly depending on the flow rate of exhaust gas passing through the oxygen concentration detection device, and the temporal change of the detected value varies greatly depending on the flow rate of exhaust gas. ing. Therefore, if the flow rate of the exhaust gas between the accelerator ON and the accelerator OFF is different, the response of the sensor is different. When the change in exhaust gas flow rate is large, the change in oxygen concentration also increases, so it is easy to distinguish between abnormal and normal, but when the change in exhaust gas flow rate is small, the change in oxygen concentration also becomes small, It is difficult to distinguish between normal and normal.
そのため、この故障判定時間を設定するのが難しく。この故障判定時間を固定してしまうと、限定された故障しか検出できなくなる。言い換えれば、故障判定時間の長さにより、アクセルＯＮからアクセルＯＦＦの移行時のエンジンの運転状態により、異常を正常と誤診断する場合や、正常を異常と誤診断する場合が生じる可能性がある。 Therefore, it is difficult to set the failure determination time. If this failure determination time is fixed, only limited failures can be detected. In other words, depending on the length of the failure determination time, there is a possibility that the abnormality is diagnosed as normal or the abnormality is diagnosed as normal depending on the operating state of the engine when the accelerator is turned on from the accelerator off. .
この対策の一つとして、酸素センサの出力の反応時間が排気ガスの流量により左右されることを考慮して、内燃機関の出力軸が回転している状態でこの内燃機関への燃料供給が遮断されたとき、内燃機関の回転数に基づいて待機時間を設定し、この設定した待機時間だけ待機した後に、酸素センサからの酸素信号の入力を開始し、この開始後からリーン側に変化するまでの時間を反応時間として、この反応時間を閾値と比較して、閾値未満では正常と判定し、閾値以上のときに異常と判定する酸素センサの異常検出装置が提案されている（例えば、特許文献１参照）。 As one of the countermeasures, considering that the reaction time of the output of the oxygen sensor depends on the flow rate of the exhaust gas, the fuel supply to the internal combustion engine is cut off while the output shaft of the internal combustion engine is rotating. Is set based on the number of revolutions of the internal combustion engine, and after waiting for the set standby time, input of an oxygen signal from the oxygen sensor is started, and from this start until it changes to the lean side An oxygen sensor abnormality detection device has been proposed in which the reaction time is compared with a threshold value, and the reaction time is determined to be normal if the reaction time is less than the threshold, and is determined to be abnormal if the reaction time is greater than or equal to the threshold (for example, Patent Literature 1).
しかしながら、この待機時間は、排気ガスの流量の変化等による酸素センサからの出力信号のバラツキを除去するために設定された時間であり、この待機時間の間の酸素センサの検出値のバラツキは排除できるが、酸素信号の入力を開始時の酸素濃度の差や、開始してからリーン側に変化するまでの間の排気ガスの流量の差を考慮することができないという問題がある。 However, this standby time is a time set to eliminate variations in the output signal from the oxygen sensor due to changes in the exhaust gas flow rate, etc., and variations in the detected value of the oxygen sensor during this standby time are excluded. However, there is a problem that it is not possible to consider the difference in oxygen concentration at the start of the input of the oxygen signal and the difference in flow rate of exhaust gas from the start to the change to the lean side.
本発明は、上記のことを鑑みてなされたものであり、その目的は、車両に搭載された内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法において、酸素濃度検出装置の故障検出の誤診断を防止して、その故障検出を容易とすることができる酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法を提供することにある。 The present invention has been made in view of the above, and an object of the present invention is to provide a failure detection system for an oxygen concentration detection device that detects the concentration of oxygen contained in the exhaust gas of an internal combustion engine mounted on a vehicle, and the oxygen concentration. Failure detection system for oxygen concentration detection device and failure detection method for oxygen concentration detection device capable of preventing erroneous diagnosis of failure detection of oxygen concentration detection device and facilitating the failure detection in the failure detection method for detection device Is to provide.
上記の目的を達成するための本発明の酸素濃度検出装置の故障検出システムは、車両に搭載された内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障を検出する酸素濃度検出装置の故障検出システムにおいて、該故障検出システムを制御する制御装置が、前記内燃機関を備える前記車両でアクセルＯＮからアクセルＯＦＦに切り替わったときに、このアクセルＯＦＦに切り替わった第１時点の前記酸素濃度検出装置を通過する排気ガスの第１流量に基づいて第１故障判定時間を設定するとともに、前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が予め設定した酸素濃度正常閾値に到達しない場合に、前記酸素濃度検出装置が故障していると判定する制御を行うように構成される。 In order to achieve the above object, a failure detection system for an oxygen concentration detection device according to the present invention provides an oxygen detection device for detecting a failure of an oxygen concentration detection device that detects the concentration of oxygen contained in exhaust gas of an internal combustion engine mounted on a vehicle. In the failure detection system of the concentration detection device, when the control device that controls the failure detection system is switched from the accelerator ON to the accelerator OFF in the vehicle including the internal combustion engine, the first time point when the accelerator is switched OFF. The first failure determination time is set based on the first flow rate of the exhaust gas passing through the oxygen concentration detection device, and the detection of the oxygen concentration detection device is performed before the first failure determination time elapses from the first time point. It is configured to perform control to determine that the oxygen concentration detection device is malfunctioning when the value does not reach a preset oxygen concentration normal threshold value It is.
ここでいう酸素濃度センサには、酸素濃度センサ（Ｏ2センサ）のみならず、ＮＯｘ濃度センサに組み込まれている酸素（Ｏ2）信号を検出するようなセンサも含む。また、ここで、アクセルＯＮとは、アクセルペダルの踏込量がゼロではない状態、即ち、運転者がアクセルを踏み込んでいる状態をいい、また、アクセルＯＦＦとは、アクセルペダルの踏込量がゼロである状態、即ち、運転者がアクセルを踏み込んでいない状態をいう。 The oxygen concentration sensor here includes not only an oxygen concentration sensor (O 2 sensor) but also a sensor that detects an oxygen (O 2 ) signal incorporated in the NOx concentration sensor. In addition, the accelerator ON is a state where the accelerator pedal depression amount is not zero, that is, the driver is depressing the accelerator pedal, and the accelerator OFF is the accelerator pedal depression amount zero. A certain state, that is, a state where the driver does not depress the accelerator.
この構成によれば、アクセルＯＮからアクセルＯＦＦに切り替わったときに、アクセルＯＦＦに切り替わった第１時点で、酸素濃度検出装置を通過する排気ガスの第１流量に基づいて設定される第１故障判定時間を用いて、酸素濃度検出装置の故障検出の診断を行うので、すなわち、酸素濃度検出装置を通過する排気ガスの流量の相違に起因する酸素濃度検出装置の応答性の相違を考慮して、酸素濃度検出装置の故障検出の診断を行うので、故障検出の誤診断を防止することができる。また、簡単な計算で容易に故障検出をすることができる。 According to this configuration, when the accelerator is switched from the accelerator ON to the accelerator OFF, the first failure determination is set based on the first flow rate of the exhaust gas passing through the oxygen concentration detection device at the first time point when the accelerator is switched OFF. Since the diagnosis of failure detection of the oxygen concentration detection device is performed using time, that is, considering the difference in responsiveness of the oxygen concentration detection device due to the difference in the flow rate of exhaust gas passing through the oxygen concentration detection device, Since the failure detection diagnosis of the oxygen concentration detection device is performed, it is possible to prevent erroneous diagnosis of failure detection. Moreover, it is possible to easily detect a failure with a simple calculation.
また、上記の酸素濃度検出装置の故障検出システムにおいて、前記制御装置が、前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が前記酸素濃度正常閾値に到達した場合において、前記第１時点から前記酸素濃度正常閾値に到達した第２時点までの経過時間が、前記第１流量と前記第２時点の前記酸素濃度検出装置を通過する排気ガスの第２流量との流量差と、前記第１流量との両方に基づいて設定される第２故障判定時間未満であるときは、前記酸素濃度検出装置が正常であると判定し、前記第１時点から前記第２時点までの経過時間が、前記第２故障判定時間以上であるときは、前記酸素濃度検出装置が故障していると判定する制御を行うように構成される。 Further, in the failure detection system for the oxygen concentration detection device, the control device detects the detected value of the oxygen concentration detection device before the first failure determination time elapses from the first time point. Is reached, the elapsed time from the first time point to the second time point when the oxygen concentration normal threshold value is reached is the first flow rate and the exhaust gas passing through the oxygen concentration detection device at the second time point. 2 is less than a second failure determination time set based on both the flow rate difference between the two flow rates and the first flow rate, it is determined that the oxygen concentration detection device is normal, and from the first time point When the elapsed time to the second time point is equal to or longer than the second failure determination time, control is performed to determine that the oxygen concentration detection device has failed.
この構成によれば、第１時点から第１故障判定時間が経過するまでに、酸素濃度検出装置の検出値が酸素濃度正常閾値に到達した場合でも、酸素濃度検出装置が正常であると判定せずに、さらに、第１時点から第２時点までの経過時間を、第１時点と第２時点の排気ガスの流量差に基づいて設定される第２故障判定時間と比較して、酸素濃度検出装置の故障検出の診断を行うので、すなわち、酸素濃度検出装置の故障検出の診断を２段階で行うので、故障検出の誤診断をより確実に防止することができる。また、簡単な計算で容易に故障検出をすることができる。 According to this configuration, even if the detection value of the oxygen concentration detection device reaches the oxygen concentration normal threshold from the first time point until the first failure determination time has elapsed, it is determined that the oxygen concentration detection device is normal. In addition, the elapsed time from the first time point to the second time point is compared with a second failure determination time set based on the flow rate difference between the first time point and the second time point, thereby detecting the oxygen concentration. Since the diagnosis of the failure detection of the apparatus is performed, that is, the diagnosis of the failure detection of the oxygen concentration detection apparatus is performed in two stages, the erroneous diagnosis of the failure detection can be prevented more reliably. Moreover, it is possible to easily detect a failure with a simple calculation.
また、上記の目的を達成するための本発明の酸素濃度検出装置の故障検出方法は、車両に搭載された内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障を検出する酸素濃度検出装置の故障検出方法において、前記内燃機関を備える前記車両でアクセルＯＮからアクセルＯＦＦに切り替わったときに、このアクセルＯＦＦに切り替わった第１時点の前記酸素濃度検出装置を通過する排気ガスの第１流量に基づいて第１故障判定時間を設定するとともに、前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が予め設定した酸素濃度正常閾値に到達しない場合に、前記酸素濃度検出装置が故障していると判定することを特徴とする方法である。 In addition, the failure detection method of the oxygen concentration detection device of the present invention for achieving the above object detects a failure of the oxygen concentration detection device that detects the concentration of oxygen contained in the exhaust gas of the internal combustion engine mounted on the vehicle. In the failure detection method of the oxygen concentration detection device, when the vehicle equipped with the internal combustion engine is switched from the accelerator ON to the accelerator OFF, the exhaust gas that passes through the oxygen concentration detection device at the first time point when the accelerator is switched OFF. The first failure determination time is set based on the first flow rate, and the detected value of the oxygen concentration detection device is set in advance to the oxygen concentration normal threshold before the first failure determination time elapses from the first time point. If the oxygen concentration detection device is not reached, it is determined that the oxygen concentration detection device is malfunctioning.
また、上記の酸素濃度検出装置の故障検出方法において、前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が前記酸素濃度正常閾値に到達した場合において、前記第１時点から前記酸素濃度正常閾値に到達した第２時点までの経過時間が、前記第１流量と前記第２時点の前記酸素濃度検出装置を通過する排気ガスの第２流量との流量差と、前記第１流量との両方に基づいて設定される第２故障判定時間未満であるときは、前記酸素濃度検出装置が正常であると判定し、前記第１時点から前記第２時点までの経過時間が、前記第２故障判定時間以上であるときは、前記酸素濃度検出装置が故障していると判定する。 Further, in the failure detection method of the oxygen concentration detection device, when the detection value of the oxygen concentration detection device reaches the oxygen concentration normal threshold before the first failure determination time elapses from the first time point. The elapsed time from the first time point to the second time point when the oxygen concentration normal threshold is reached is a flow rate between the first flow rate and the second flow rate of the exhaust gas passing through the oxygen concentration detection device at the second time point. When it is less than the second failure determination time set based on both the difference and the first flow rate, it is determined that the oxygen concentration detection device is normal, and from the first time point to the second time point When the elapsed time is equal to or longer than the second failure determination time, it is determined that the oxygen concentration detection device has failed.
これらの方法によれば、上記の酸素濃度検出装置の故障検出システムと同様の作用効果を奏することができる。 According to these methods, it is possible to achieve the same effects as the above-described failure detection system of the oxygen concentration detection device.
（請求項１の作用効果と同様）
本発明の酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法によれば、アクセルＯＮからアクセルＯＦＦに切り替わったときに、酸素濃度検出装置を通過する排気ガスの流量の相違に起因する酸素濃度検出装置の応答性の相違を考慮して、酸素濃度検出装置の故障検出の診断を行うので、故障検出の誤診断を防止して、その故障検出を容易とすることができる。
(Same as the effect of claim 1)
According to the failure detection system of the oxygen concentration detection device and the failure detection method of the oxygen concentration detection device of the present invention, when the accelerator is switched from the accelerator ON to the accelerator OFF, the difference is caused by the difference in the flow rate of the exhaust gas passing through the oxygen concentration detection device. In view of the difference in responsiveness of the oxygen concentration detection device, the failure detection of the oxygen concentration detection device is diagnosed, so that misdiagnosis of the failure detection can be prevented and the failure detection can be facilitated.
以下、本発明に係る実施の形態の酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法について図面を参照しながら説明する。なお、ここでいう酸素濃度センサには、酸素濃度センサ（Ｏ2センサ）のみならず、ＮＯｘ濃度センサに組み込まれている酸素（Ｏ2）信号を検出するようなセンサも含む。 Hereinafter, a failure detection system for an oxygen concentration detection device and a failure detection method for an oxygen concentration detection device according to an embodiment of the present invention will be described with reference to the drawings. The oxygen concentration sensor here includes not only an oxygen concentration sensor (O 2 sensor) but also a sensor that detects an oxygen (O 2 ) signal incorporated in the NOx concentration sensor.
この実施の形態の酸素濃度検出装置の故障検出システムは、トラックなどの車両に搭載されたディーゼルエンジン等の内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障を検出するシステムである。これらの酸素濃度検出装置は、λセンサとも呼ばれて、排気ガス通路に配置されて、内燃機関の燃料噴射量と吸気量との関係を見るために、排気ガス浄化処理装置の制御で使用するために、排気ガス中の酸素濃度を検出している。また、ＮＯｘ濃度センサの一部でも酸素濃度を検出している。 The failure detection system of the oxygen concentration detection device of this embodiment detects a failure of the oxygen concentration detection device that detects the concentration of oxygen contained in the exhaust gas of an internal combustion engine such as a diesel engine mounted on a vehicle such as a truck. System. These oxygen concentration detection devices, also called λ sensors, are arranged in the exhaust gas passage and are used in the control of the exhaust gas purification processing device to see the relationship between the fuel injection amount and the intake air amount of the internal combustion engine. Therefore, the oxygen concentration in the exhaust gas is detected. Further, the oxygen concentration is detected by a part of the NOx concentration sensor.
そして、本発明においては、この故障検出システムを制御する制御装置が次の制御を行うように構成される。つまり、図２に示すように、内燃機関を備える車両で、内燃機関を作動させて車両を走行させている際に、アクセルペダルの踏込量がゼロではない状態、即ち、運転者がアクセルを踏み込んでいる状態であるアクセルＯＮから、アクセルペダルの踏込量がゼロである状態、即ち、運転者がアクセルを踏み込んでいない状態であるアクセルＯＦＦに切り替わったときに、このアクセルＯＦＦに切り替わった第１時点ｔ１の酸素濃度検出装置を通過する排気ガスの第１流量ＥＧ１に基づいて第１故障判定時間Δｔ１ｃを設定する。 And in this invention, the control apparatus which controls this failure detection system is comprised so that the following control may be performed. That is, as shown in FIG. 2, when the vehicle is provided with an internal combustion engine and the internal combustion engine is operated to drive the vehicle, the accelerator pedal depression amount is not zero, that is, the driver depresses the accelerator. The first point in time when the accelerator pedal is switched from the accelerator ON state where the accelerator pedal is depressed to the state where the accelerator pedal depression amount is zero, that is, when the driver switches to the accelerator OFF state where the accelerator pedal is not depressed. A first failure determination time Δt1c is set based on the first flow rate EG1 of the exhaust gas passing through the oxygen concentration detection device at t1.
この排気ガスの第１流量ＥＧ１は、例えば、排気通路に流量センサを設けて、この流量センサによる検出値を用いるが、この流量センサの配設位置は、故障を検出する酸素濃度センサ近傍に設けることが好ましい。なお、排気ガス量を測定する代わりに、吸気量や吸気量を使った推定排気流量で代用してもよい。 As the first flow rate EG1 of the exhaust gas, for example, a flow rate sensor is provided in the exhaust passage, and a detection value by the flow rate sensor is used. The flow rate sensor is disposed near the oxygen concentration sensor that detects a failure. It is preferable. Instead of measuring the exhaust gas amount, an intake air amount or an estimated exhaust gas flow rate using the intake air amount may be substituted.
それと共に、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達しない場合に、酸素濃度検出装置が故障していると判定する。 At the same time, when the detection value D1 of the oxygen concentration detection device does not reach the preset oxygen concentration normal threshold Dc before the first failure determination time Δt1c elapses from the first time point t1, the oxygen concentration detection device fails. It is determined that
この第１故障判定時間Δｔ１ｃの設定は、予め行われた実験の結果などから、第１流量ＥＧ１と第１故障判定時間Δｔ１ｃの関係を設定し、制御装置に記憶されたマップデータ等を参照して行う。この第１故障判定時間Δｔ１ｃは酸素濃度センサや排気ガス量の流量計の配置場所などにもよるが、排気ガスの第１流量ＥＧ１が多いとガスの入れ替わりが早くなるので、第１故障判定時間Δｔ１ｃは短くなる。イメージ的には、図３に示すようなものであるが、アクセルＯＮｋらＯＦＦした直後の過渡期になるので、単純な直線になるとは限らず、実際的にはそれぞれのケースによる。また、酸素濃度正常閾値Ｄｃも、予め行われた実験の結果などから、設定しておき、制御装置に記憶しておく。この酸素濃度正常閾値Ｄｃは酸素濃度が約２１％となるような検出値、又は、それに近いが２１％よりも低い検出値として設定される。 The first failure determination time Δt1c is set by setting the relationship between the first flow rate EG1 and the first failure determination time Δt1c from the result of an experiment performed in advance, and referring to map data stored in the control device. Do it. Although this first failure determination time Δt1c depends on the location of the oxygen concentration sensor and the exhaust gas flow meter, the first failure determination time because the gas change becomes faster when the exhaust gas first flow rate EG1 is large. Δt1c becomes shorter. Although the image is as shown in FIG. 3, since it is a transition period immediately after the accelerator ONk is turned OFF, it is not always a simple straight line, and actually depends on each case. The oxygen concentration normal threshold value Dc is also set from the results of experiments performed in advance and stored in the control device. The oxygen concentration normal threshold Dc is set as a detection value at which the oxygen concentration is about 21%, or a detection value close to it but lower than 21%.
更に、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が酸素濃度正常閾値Ｄｃに到達した場合には、第１流量ＥＧ１と、第２時点ｔ２の酸素濃度検出装置を通過する排気ガスの第２流量ＥＧ２との流量差ΔＥＧ＝ＥＧ１−ＥＧ２と、第１流量ＥＧ１との両方に基づいて設定される第２故障判定時間Δｔ２ｃを設定する。 Furthermore, when the detection value D1 of the oxygen concentration detection device reaches the oxygen concentration normal threshold Dc before the first failure determination time Δt1c elapses from the first time t1, the first flow rate EG1 and the second time t2 The second failure determination time Δt2c that is set based on both the flow rate difference ΔEG = EG1−EG2 of the second flow rate EG2 of the exhaust gas that passes through the oxygen concentration detection device and the first flow rate EG1 is set.
この第２故障判定時間Δｔ２ｃの設定は、予め行われた実験の結果などから、流量差ΔＥＧと第１流量ＥＧ１をベースにした第２故障判定時間Δｔ２ｃを設定し、これをデータマップ化して制御装置に記憶しおき、制御時にこのマップデータを参照して第２故障判定時間Δｔ２ｃを求めて設定を行う。イメージ的には、図４に示すようなもので、流量差ΔＥＧと第１流量ＥＧ１の両方が小さければ、第２故障判定時間Δｔ２ｃは長く、流量差ΔＥＧと第１流量ＥＧ１の両方が大きければ、第２故障判定時間Δｔ２ｃは短くなるが、それぞれのケースによる。 The second failure determination time Δt2c is set by setting a second failure determination time Δt2c based on the flow rate difference ΔEG and the first flow rate EG1, based on the result of an experiment performed in advance, and making this a data map. The second failure determination time Δt2c is determined and set by referring to this map data during control. As shown in FIG. 4, if both the flow rate difference ΔEG and the first flow rate EG1 are small, the second failure determination time Δt2c is long, and if both the flow rate difference ΔEG and the first flow rate EG1 are large. The second failure determination time Δt2c is shortened, but depends on each case.
そして、第１時点ｔ１から酸素濃度正常閾値Ｄｃに到達した第２時点ｔ２までの経過時間Δｔ２が、この第２故障判定時間Δｔ２ｃ未満であるときは、酸素濃度検出装置が正常であると判定し、この経過時間Δｔ２が、第２故障判定時間Δｔ２ｃ以上であるときは、酸素濃度検出装置が故障していると判定する。 When the elapsed time Δt2 from the first time point t1 to the second time point t2 when the oxygen concentration normal threshold value Dc is reached is less than the second failure determination time Δt2c, it is determined that the oxygen concentration detection device is normal. When the elapsed time Δt2 is equal to or longer than the second failure determination time Δt2c, it is determined that the oxygen concentration detection device has failed.
これにより、アクセルＯＮからアクセルＯＦＦに切り替わったときに、アクセルＯＦＦに切り替わった第１時点ｔ１で、酸素濃度検出装置を通過する排気ガスの第１流量ＥＧ１に基づいて設定される第１故障判定時間Δｔ１ｃを用いて、酸素濃度検出装置の故障検出の診断を行うので、すなわち、酸素濃度検出装置を通過する排気ガスの流量の相違に起因する酸素濃度検出装置の応答性の相違を考慮して、酸素濃度検出装置の故障検出の診断を行うので、故障検出の誤診断を防止することができる。また、簡単な計算で容易に故障検出をすることができる。 Thus, when the accelerator is switched from the accelerator ON to the accelerator OFF, the first failure determination time set based on the first flow rate EG1 of the exhaust gas passing through the oxygen concentration detection device at the first time point t1 when the accelerator is switched OFF. Since Δt1c is used to diagnose the failure detection of the oxygen concentration detection device, that is, considering the difference in the responsiveness of the oxygen concentration detection device due to the difference in the flow rate of the exhaust gas passing through the oxygen concentration detection device, Since the failure detection diagnosis of the oxygen concentration detection device is performed, it is possible to prevent erroneous diagnosis of failure detection. Moreover, it is possible to easily detect a failure with a simple calculation.
更に、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が酸素濃度正常閾値Ｄｃに到達した場合でも、酸素濃度検出装置が正常であると判定せずに、さらに、第１時点ｔ１から第２時点ｔ２までの経過時間Δｔ２を、第１時点ｔ１と第２時点ｔ２の排気ガスの流量差ΔＥＧに基づいて設定される第２故障判定時間Δｔ２ｃと比較して、酸素濃度検出装置の故障検出の診断を行うので、すなわち、酸素濃度検出装置の故障検出の診断を２段階で行うので、故障検出の誤診断をより確実に防止することができる。また、簡単な計算で容易に故障検出をすることができる。 Further, even when the detection value D1 of the oxygen concentration detection device reaches the oxygen concentration normal threshold Dc before the first failure determination time Δt1c elapses from the first time point t1, it is determined that the oxygen concentration detection device is normal. In addition, an elapsed time Δt2 from the first time point t1 to the second time point t2 is set to a second failure determination time Δt2c that is set based on the exhaust gas flow rate difference ΔEG between the first time point t1 and the second time point t2. In comparison, since the failure detection diagnosis of the oxygen concentration detection device is performed, that is, the failure detection diagnosis of the oxygen concentration detection device is performed in two stages, the erroneous diagnosis of failure detection can be prevented more reliably. Moreover, it is possible to easily detect a failure with a simple calculation.
次に、本願発明に係る実施の形態の酸素濃度検出装置の故障検出方法について説明する。この方法は、車両に搭載された内燃機関の排気ガスに含まれる酸素の濃度を検出する酸素濃度検出装置の故障を検出する酸素濃度検出装置の故障検出方法であり、内燃機関を備える車両でアクセルＯＮからアクセルＯＦＦに切り替わったときに、このアクセルＯＦＦに切り替わった第１時点ｔ１の酸素濃度検出装置を通過する排気ガスの第１流量ＥＧ１に基づいて第１故障判定時間Δｔ１ｃを設定するとともに、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達しない場合に、酸素濃度検出装置が故障していると判定する方法である。 Next, a failure detection method for the oxygen concentration detection apparatus according to the embodiment of the present invention will be described. This method is a failure detection method for an oxygen concentration detection device that detects a failure of an oxygen concentration detection device that detects the concentration of oxygen contained in exhaust gas of an internal combustion engine mounted on a vehicle. The first failure determination time Δt1c is set based on the first flow rate EG1 of the exhaust gas that passes through the oxygen concentration detection device at the first time point t1 when the accelerator is switched off when the accelerator is switched from the ON position to the accelerator OFF position. When the detection value D1 of the oxygen concentration detection device does not reach the preset oxygen concentration normal threshold Dc before the first failure determination time Δt1c elapses from one time point t1, it is determined that the oxygen concentration detection device has failed. It is a method to do.
また、更に、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が酸素濃度正常閾値Ｄｃに到達した場合において、第１時点ｔ１から酸素濃度正常閾値Ｄｃに到達した第２時点ｔ２までの経過時間Δｔ２が、第１流量ＥＧ１と、第２時点ｔ２の酸素濃度検出装置を通過する排気ガスの第２流量ＥＧ２との流量差ΔＥＧ（＝ＥＧ１−ＥＧ２）に基づいて設定される第２故障判定時間Δｔ２ｃ未満であるときは、酸素濃度検出装置が正常であると判定し、第１時点ｔ１から第２時点ｔ２までの経過時間Δｔ２が、第２故障判定時間Δｔ２ｃ以上であるときは、酸素濃度検出装置が故障していると判定する。 Furthermore, when the detection value D1 of the oxygen concentration detection device reaches the oxygen concentration normal threshold Dc before the first failure determination time Δt1c elapses from the first time t1, the oxygen concentration normal threshold from the first time t1. The elapsed time Δt2 up to the second time point t2 when reaching Dc is the flow rate difference ΔEG (= EG1-EG2) between the first flow rate EG1 and the second flow rate EG2 of the exhaust gas passing through the oxygen concentration detection device at the second time point t2. ) Is set to be less than the second failure determination time Δt2c, it is determined that the oxygen concentration detection device is normal, and the elapsed time Δt2 from the first time point t1 to the second time point t2 is the second failure time. When it is not less than the determination time Δt2c, it is determined that the oxygen concentration detection device has failed.
次に図１の制御フローを参照しながら、この実施の形態の酸素濃度検出装置の故障検出方法について説明する。酸素濃度検出装置の故障検出を行うとして上位の制御フローから図１の制御フローが呼ばれると、ステップＳ１１で、アクセルＯＮからアクセルＯＦＦに切り替わったときであるか否かを判定する。この判定で、否であれば、予め設定された制御時間を経過した後、ステップＳ１１に戻る。 Next, a failure detection method for the oxygen concentration detection device of this embodiment will be described with reference to the control flow of FIG. When the control flow of FIG. 1 is called from the upper control flow for detecting the failure of the oxygen concentration detection device, it is determined in step S11 whether or not the accelerator is switched from the accelerator ON to the accelerator OFF. If this determination is NO, the control returns to step S11 after a preset control time has elapsed.
また、ステップＳ１１で、アクセルＯＮからアクセルＯＦＦに切り替わったときには、ステップＳ１２で、このアクセルＯＦＦに切り替わった第１時点ｔ１の酸素濃度検出装置を通過する排気ガスの第１流量ＥＧ１を検出若しくは算出し、この第１流量ＥＧ１に基づいて予め設定されたマップデータ等から第１故障判定時間Δｔ１ｃを設定する。それと共に、経過時間Δｔをゼロにリセットしてからカウントを開始する。 Further, when the accelerator is switched from the accelerator ON to the accelerator OFF in step S11, the first flow rate EG1 of the exhaust gas passing through the oxygen concentration detection device at the first time point t1 when the accelerator is switched OFF is detected or calculated in step S12. The first failure determination time Δt1c is set from map data set in advance based on the first flow rate EG1. At the same time, the count is started after the elapsed time Δt is reset to zero.
次のステップＳ１３で、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達したか否かを判定する。この判定で、否の場合には、ステップＳ１４に行き、ステップＳ１４で、経過時間Δｔが第１故障判定時間Δｔ１ｃ未満であるか否かを判定し、未満であれば、経過時間Δｔのカウントを継続すると共に、予め設定した制御時間を経過した後、ステップＳ１３に戻る。 In the next step S13, it is determined whether or not the detection value D1 of the oxygen concentration detection device has reached a preset oxygen concentration normal threshold Dc. If this determination is negative, the procedure goes to step S14, where it is determined whether or not the elapsed time Δt is less than the first failure determination time Δt1c, and if it is less, the elapsed time Δt is counted. At the same time, after a preset control time has elapsed, the process returns to step S13.
このステップＳ１４で、経過時間Δｔが第１故障判定時間Δｔ１ｃ未満でなければ、ステップＳ２１に行き、酸素濃度検出装置が故障しているとの判定値を発信する。そして、リターンに行き、図１の制御フローを終了し、上位の制御フローに戻る。 In step S14, if the elapsed time Δt is not less than the first failure determination time Δt1c, the process goes to step S21 to transmit a determination value that the oxygen concentration detection device has failed. And it goes to a return, the control flow of FIG. 1 is complete | finished, and it returns to a high-order control flow.
また、ステップＳ１３で、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達した場合には、ステップＳ１５に行き、経過時間Δｔが第１故障判定時間Δｔ１ｃ未満であるか否かを判定し、未満でなければ、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達しないとして、ステップＳ２１に行き、酸素濃度検出装置が故障しているとの判定値を発信する。そして、リターンに行き、図１の制御フローを終了し、上位の制御フローに戻る。 In step S13, if the detection value D1 of the oxygen concentration detection device has reached the preset normal oxygen concentration threshold value Dc, the process goes to step S15, and whether the elapsed time Δt is less than the first failure determination time Δt1c. If it is not less, the detection value D1 of the oxygen concentration detection device does not reach the preset normal oxygen concentration threshold value Dc until the first failure determination time Δt1c elapses from the first time point t1. Going to S21, a determination value indicating that the oxygen concentration detection device has failed is transmitted. And it goes to a return, the control flow of FIG. 1 is complete | finished, and it returns to a high-order control flow.
ステップＳ１５で、経過時間Δｔが第１故障判定時間Δｔ１ｃ未満である場合には、第１時点ｔ１から第１故障判定時間Δｔ１ｃが経過するまでに、酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達したとして、ステップＳ１６で、この酸素濃度検出装置の検出値Ｄ１が予め設定した酸素濃度正常閾値Ｄｃに到達した第２時点ｔ２の酸素濃度検出装置を通過する排気ガスの第２流量ＥＧ１を検出若しくは算出する。また、第２時点ｔ２の酸素濃度検出装置を通過する排気ガスの第２流量ＥＧ２との流量差ΔＥＧ（＝ＥＧ１−ＥＧ２）を算出する。また、この流量差ΔＥＧから第２故障判定時間Δｔ２ｃを設定する。 In step S15, when the elapsed time Δt is less than the first failure determination time Δt1c, the detection value D1 of the oxygen concentration detection device is set in advance until the first failure determination time Δt1c elapses from the first time point t1. Assuming that the oxygen concentration normal threshold value Dc has been reached, in step S16, the detected value D1 of the oxygen concentration detection device reaches the oxygen concentration normal threshold value Dc, and the exhaust gas passing through the oxygen concentration detection device at the second time point t2 has reached. The second flow rate EG1 is detected or calculated. Further, a flow rate difference ΔEG (= EG1−EG2) with the second flow rate EG2 of the exhaust gas passing through the oxygen concentration detection device at the second time point t2 is calculated. Further, the second failure determination time Δt2c is set from the flow rate difference ΔEG.
そして、次のステップＳ１７で、経過時間Δｔが、この第２故障判定時間Δｔ２ｃ未満であるか否かを判定し、否であるときは、ステップＳ２１に行き、酸素濃度検出装置が故障しているとの判定値を発信する。そして、リターンに行き、図１の制御フローを終了し、上位の制御フローに戻る。一方、未満であるときは、ステップＳ２２に行き、酸素濃度検出装置が正常であるとの判定値を発信し、そして、リターンに行き、図１の制御フローを終了し、上位の制御フローに戻る。これらの制御により、上記の酸素濃度検出装置の故障検出方法を実施できる。 Then, in the next step S17, it is determined whether or not the elapsed time Δt is less than the second failure determination time Δt2c. If not, the process goes to step S21 and the oxygen concentration detection device has failed. The judgment value is transmitted. And it goes to a return, the control flow of FIG. 1 is complete | finished, and it returns to a high-order control flow. On the other hand, if it is less, go to step S22, send a determination value that the oxygen concentration detection device is normal, go to return, end the control flow of FIG. 1, and return to the upper control flow. . With these controls, the failure detection method for the oxygen concentration detection device can be implemented.
上記の構成の酸素濃度検出装置の故障検出システム及び酸素濃度検出装置の故障検出方法によれば、アクセルＯＮからアクセルＯＦＦに切り替わったときに、酸素濃度検出装置を通過する排気ガスの流量の相違に起因する酸素濃度検出装置の応答性の相違を考慮して、酸素濃度検出装置の故障検出の診断を行うので、故障検出の誤診断を防止して、その故障検出を容易とすることができる。 According to the failure detection system of the oxygen concentration detection device and the failure detection method of the oxygen concentration detection device configured as described above, when the accelerator is switched from ON to OFF, the flow rate of the exhaust gas passing through the oxygen concentration detection device is different. In consideration of the difference in the responsiveness of the oxygen concentration detection device, the failure detection diagnosis of the oxygen concentration detection device is performed, so that misdiagnosis of failure detection can be prevented and the failure detection can be facilitated.
Ｄ１ 酸素濃度検出装置の検出値
Ｄｃ 酸素濃度正常閾値
ｔ１ 第１時点
ｔ２ 第２時点
ＥＧ１ 排気ガスの第１流量
ＥＧ２ 排気ガスの第２流量
Δｔ１ｃ 第１故障判定時間
Δｔ２ｃ 第２故障判定時間
Δｔ２ 第１時点から第２時点までの経過時間
Δｔ 第１時点からの経過時間
ΔＥＧ 排気ガスの流量差
D1 Detection value Dc of oxygen concentration detection device Dc Oxygen concentration normal threshold t1 First time point t2 Second time point EG1 First flow rate EG2 of exhaust gas Second flow rate of exhaust gas Δt1c First failure determination time Δt2c Second failure determination time Δt2 First Elapsed time from the time point to the second time point Δt Elapsed time from the first time point ΔEG Exhaust gas flow rate difference
Claims (4)
該故障検出システムを制御する制御装置が、
前記内燃機関を備える前記車両でアクセルＯＮからアクセルＯＦＦに切り替わったときに、
このアクセルＯＦＦに切り替わった第１時点の前記酸素濃度検出装置を通過する排気ガスの第１流量に基づいて第１故障判定時間を設定するとともに、
前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が予め設定した酸素濃度正常閾値に到達しない場合に、前記酸素濃度検出装置が故障していると判定する制御を行うように構成されることを特徴とする酸素濃度検出装置の故障検出システム。 In a failure detection system for an oxygen concentration detection device for detecting a failure of an oxygen concentration detection device for detecting the concentration of oxygen contained in exhaust gas of an internal combustion engine mounted on a vehicle,
A control device for controlling the failure detection system;
When switching from accelerator ON to accelerator OFF in the vehicle including the internal combustion engine,
The first failure determination time is set based on the first flow rate of the exhaust gas passing through the oxygen concentration detection device at the first time point when the accelerator is switched off,
When the detected value of the oxygen concentration detection device does not reach a preset oxygen concentration normal threshold before the first failure determination time elapses from the first time point, the oxygen concentration detection device has failed. A failure detection system for an oxygen concentration detection device, characterized in that it is configured to perform control for determination.
前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が前記酸素濃度正常閾値に到達した場合において、
前記第１時点から前記酸素濃度正常閾値に到達した第２時点までの経過時間が、前記第１流量と前記第２時点の前記酸素濃度検出装置を通過する排気ガスの第２流量との流量差と、前記第１流量との両方に基づいて設定される第２故障判定時間未満であるときは、前記酸素濃度検出装置が正常であると判定し、
前記第１時点から前記第２時点までの経過時間が、前記第２故障判定時間以上であるときは、前記酸素濃度検出装置が故障していると判定する制御を行うように構成される請求項１に記載の酸素濃度検出装置の故障検出システム。 The control device is
When the detection value of the oxygen concentration detection device reaches the oxygen concentration normal threshold before the first failure determination time has elapsed from the first time point,
The elapsed time from the first time point to the second time point when the oxygen concentration normal threshold is reached is a flow rate difference between the first flow rate and the second flow rate of the exhaust gas passing through the oxygen concentration detection device at the second time point. And when it is less than the second failure determination time set based on both the first flow rate and the oxygen concentration detection device is determined to be normal,
The control unit is configured to perform control to determine that the oxygen concentration detection device has failed when an elapsed time from the first time point to the second time point is equal to or greater than the second failure determination time. The fault detection system of the oxygen concentration detection apparatus of 1.
前記内燃機関を備える前記車両でアクセルＯＮからアクセルＯＦＦに切り替わったときに、このアクセルＯＦＦに切り替わった第１時点の前記酸素濃度検出装置を通過する排気ガスの第１流量に基づいて第１故障判定時間を設定するとともに、
前記第１時点から前記第１故障判定時間が経過するまでに、前記酸素濃度検出装置の検出値が予め設定した酸素濃度正常閾値に到達しない場合に、前記酸素濃度検出装置が故障していると判定することを特徴とする酸素濃度検出装置の故障検出方法。 In a failure detection method for an oxygen concentration detection device for detecting a failure of an oxygen concentration detection device for detecting the concentration of oxygen contained in exhaust gas of an internal combustion engine mounted on a vehicle,
When the vehicle having the internal combustion engine is switched from accelerator ON to accelerator OFF, a first failure determination is made based on the first flow rate of exhaust gas passing through the oxygen concentration detection device at the first time point when the accelerator is switched OFF. Set time and
When the detected value of the oxygen concentration detection device does not reach a preset oxygen concentration normal threshold before the first failure determination time elapses from the first time point, the oxygen concentration detection device has failed. A failure detection method for an oxygen concentration detection device, characterized by: determining.
前記第１時点から前記酸素濃度正常閾値に到達した第２時点までの経過時間が、前記第１流量と前記第２時点の前記酸素濃度検出装置を通過する排気ガスの第２流量との流量差と、前記第１流量との両方に基づいて設定される第２故障判定時間未満であるときは、前記酸素濃度検出装置が正常であると判定し、
前記第１時点から前記第２時点までの経過時間が、前記第２故障判定時間以上であるときは、前記酸素濃度検出装置が故障していると判定する請求項３に記載の酸素濃度検出装置の故障検出方法。 When the detection value of the oxygen concentration detection device reaches the oxygen concentration normal threshold before the first failure determination time has elapsed from the first time point,
The elapsed time from the first time point to the second time point when the oxygen concentration normal threshold is reached is a flow rate difference between the first flow rate and the second flow rate of the exhaust gas passing through the oxygen concentration detection device at the second time point. And when it is less than the second failure determination time set based on both the first flow rate and the oxygen concentration detection device is determined to be normal,
The oxygen concentration detection device according to claim 3, wherein when the elapsed time from the first time point to the second time point is equal to or longer than the second failure determination time, it is determined that the oxygen concentration detection device has failed. Failure detection method.
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