JP7298512B2 - Exhaust purification system and its control method - Google Patents

Exhaust purification system and its control method Download PDF

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JP7298512B2
JP7298512B2 JP2020031807A JP2020031807A JP7298512B2 JP 7298512 B2 JP7298512 B2 JP 7298512B2 JP 2020031807 A JP2020031807 A JP 2020031807A JP 2020031807 A JP2020031807 A JP 2020031807A JP 7298512 B2 JP7298512 B2 JP 7298512B2
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竜介 藤野
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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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Description

本開示は排気浄化システムおよびその制御方法に関し、より詳細には排気通路に配置された触媒装置に流入する排気を加熱装置により加熱する排気浄化システムおよびその制御方法に関する。 TECHNICAL FIELD The present disclosure relates to an exhaust purification system and its control method, and more particularly to an exhaust purification system that heats exhaust gas flowing into a catalytic device arranged in an exhaust passage with a heating device and its control method.

エンジンの排気通路に加熱装置を配置して、その加熱装置により排気を加熱する排気浄化システムが提案されている（例えば、特許文献１参照）。 An exhaust purification system has been proposed in which a heating device is arranged in an exhaust passage of an engine and exhaust gas is heated by the heating device (see, for example, Patent Document 1).

特開２０１０－１６９０７０号公報JP 2010-169070 A

ところで、排気浄化システムが備える触媒装置はその性能が十分に発揮される温度帯が予め決まっている。そこで、上記の特許文献１に記載の発明は、加熱装置により加熱した排気が流入する触媒装置の入口を通過する排気の温度とその温度帯に基づいて設定した設定温度を比較して加熱装置による加熱とその加熱の停止とを制御している。 By the way, the temperature range in which the catalytic device provided in the exhaust gas purification system exhibits its performance sufficiently is predetermined. Therefore, the invention described in Patent Document 1 above compares the temperature of the exhaust gas passing through the inlet of the catalyst device into which the exhaust gas heated by the heating device flows and the set temperature set based on the temperature range, and the heating device It controls heating and stopping of that heating.

しかし、触媒装置の入口を通過する排気の温度が温度帯の下限値に達しただけでは、触媒装置の全体が昇温されておらず、加熱が不十分な状態に陥るという問題がある。一方で、触媒装置の入口を通過する排気の温度が温度帯の上限に達するまで加熱装置による加熱を継続すると、触媒装置を十分に昇温させることが可能となるが、加熱装置で消費されるエネルギーが大きくなるという問題がある。 However, if the temperature of the exhaust gas passing through the inlet of the catalytic converter reaches the lower limit value of the temperature zone, the catalytic converter as a whole is not heated up, resulting in insufficient heating. On the other hand, if heating by the heating device is continued until the temperature of the exhaust gas passing through the inlet of the catalytic device reaches the upper limit of the temperature zone, the catalytic device can be sufficiently heated, but the heating device consumes There is a problem of increased energy.

これらの問題に対して、触媒装置の入口を通過する排気の温度、排気流量、触媒装置の容量や熱容量などを用いてその触媒装置の全体の温度や触媒装置の中心部の温度を予測し、予測したその温度に基づいて加熱装置による加熱を制御する方法がある。また、ＰＩＤ制御により触媒装置の全体が十分に加熱され、かつ、加熱装置で消費されるエネルギーが過剰に大きくならないようにゲインの設定など制御を適正化して加熱装置による加熱を制御する方法がある。 To solve these problems, the temperature of the entire catalytic device and the temperature of the central part of the catalytic device are predicted using the temperature of the exhaust gas passing through the inlet of the catalytic device, the flow rate of the exhaust gas, the capacity and heat capacity of the catalytic device, and the like. There is a method of controlling the heating by the heating device based on its predicted temperature. In addition, there is a method of controlling the heating by the heating device by optimizing control such as gain setting so that the entire catalytic device is sufficiently heated by PID control and the energy consumed by the heating device does not become excessively large. .

しかしながら、それらの方法では計算負荷が重くなるという問題や計算に用いるモデル化やＰＩＤ制御に用いるゲインの設定など制御の適正化に要するコストが高くなるという問題がある。 However, these methods have a problem that the calculation load becomes heavy, and there is a problem that the modeling used for the calculation and the cost required for setting the gain used for the PID control to optimize the control are high.

本開示の目的は、触媒装置に対する十分な昇温効果と加熱装置で消費されるエネルギーの低減とを両立しつつ、計算負荷を低減するとともに制御の適正化に要するコストを低減する排気浄化システムおよびその制御方法を提供することである。 It is an object of the present disclosure to provide an exhaust purification system that reduces the computational load and the cost required for proper control while achieving both a sufficient temperature raising effect on the catalyst device and a reduction in the energy consumed by the heating device. It is to provide the control method.

上記の目的を達成する本発明の一態様の排気浄化システムは、排気通路に配置された触媒装置と、バッテリからの電力の供給によりこの触媒装置を加熱する加熱装置と、を備える排気浄化システムにおいて、前記触媒装置の入口を通過する排気の入口温度を取得する入口温度取得装置と、前記触媒装置の出口を通過する排気の出口温度を取得する出口温度取得装置と、前記加熱装置による加熱の駆動を制御する制御装置と、を備え、前記制御装置に入口設定温度と出口設定温度とが予め設定されて、前記出口設定温度が、前記触媒装置が活性化したことを判定可能な値の中での下限を示す下限温度に設定されていて、前記入口設定温度が、前記触媒装置の入口側の温度と出口側の温度との間に生じる温度差に基づいて前記出口設定温度よりも高い温度に設定されていて、前記制御装置は、前記加熱装置の駆動が停止している状態で前記出口温度取得装置が取得した前記出口温度が前記出口設定温度よりも低い場合に前記加熱装置を駆動し、前記加熱装置が駆動している状態で前記入口温度取得装置が取得した前記入口温度が前記入口設定温度以上の場合に前記加熱装置の駆動を停止する制御を行う構成であることを特徴とする。 According to one aspect of the present invention, there is provided an exhaust gas purification system that achieves the above objects, and includes a catalytic device arranged in an exhaust passage, and a heating device that heats the catalytic device by being supplied with power from a battery. an inlet temperature acquiring device for acquiring the inlet temperature of exhaust gas passing through the inlet of the catalyst device; an outlet temperature acquiring device for acquiring the outlet temperature of the exhaust gas passing through the outlet of the catalytic device; and driving of heating by the heating device. an inlet set temperature and an outlet set temperature are set in advance in the control device , and the outlet set temperature is within a value that can determine that the catalyst device is activated and the inlet set temperature is set to a temperature higher than the outlet set temperature based on the temperature difference between the inlet side temperature and the outlet side temperature of the catalyst device. is set, and the control device drives the heating device when the outlet temperature acquired by the outlet temperature acquisition device is lower than the outlet set temperature in a state where the heating device is not driven; The heating device is controlled to stop driving when the inlet temperature obtained by the inlet temperature obtaining device is equal to or higher than the inlet set temperature while the heating device is being driven.

上記の目的を達成する本発明の一態様の排気浄化システムの制御方法は、制御装置によりバッテリからの電力が供給されて触媒装置を加熱する加熱装置を制御する排気浄化システムの制御方法において、前記制御装置に予め入口設定温度と出口設定温度とを設定しておき、前記出口設定温度が、前記触媒装置が活性化したことを判定可能な値の中での下限を示す下限温度に設定されていて、前記入口設定温度が、前記触媒装置の入口側の温度と出口側の温度との間に生じる温度差に基づいて前記出口設定温度よりも高い温度に設定されていて、前記触媒装置の入口を通過する排気の入口温度を取得するとともに、前記触媒装置の出口を通過する排気の出口温度を取得し、前記制御装置により、前記加熱装置の駆動が停止している状態で取得した前記出口温度が前記出口設定温度よりも低い場合に前記加熱装置を駆動し、前記加熱装置が駆動している状態で取得した前記入口温度が前記入口設定温度以上のときに前記加熱装置の駆動を停止することを特徴とする。 According to one aspect of the present invention, there is provided a control method for an exhaust gas purification system for achieving the above-described object, in which the control device controls a heating device that is supplied with electric power from a battery to heat a catalyst device , An inlet set temperature and an outlet set temperature are set in advance in the control device, and the outlet set temperature is set to a lower limit temperature indicating the lower limit among values that allow determination that the catalyst device is activated. The inlet set temperature is set to a temperature higher than the outlet set temperature based on a temperature difference between the inlet side temperature and the outlet side temperature of the catalyst device, and acquires the inlet temperature of the exhaust gas passing through the catalyst device, acquires the outlet temperature of the exhaust gas passing through the outlet of the catalyst device, and acquires the outlet temperature acquired by the control device while the heating device is not driven is lower than the outlet set temperature, and stops driving the heating device when the inlet temperature obtained while the heating device is in operation is equal to or higher than the inlet set temperature. characterized by

本発明の一態様によれば、触媒装置の入口温度に加えて出口温度を判定することで触媒装置の昇温状態を適切に見極めることが可能となる。それ故、触媒装置に対する十分な昇温効果と加熱装置で消費されるエネルギーの低減とを両立することができる。また、入口温度と出口温度との二つの温度を用いることで、触媒装置自体の温度を推定する方法やＰＩＤ制御を用いる方法に比して、計算負荷を低減するとともに制御の適正化に要するコストを低減することができる。 According to one aspect of the present invention, it is possible to appropriately determine the temperature rise state of the catalytic device by determining the outlet temperature in addition to the inlet temperature of the catalytic device. Therefore, it is possible to achieve both a sufficient temperature raising effect on the catalytic device and a reduction in the energy consumed by the heating device. In addition, by using two temperatures, the inlet temperature and the outlet temperature, compared to the method of estimating the temperature of the catalyst device itself or the method of using PID control, the calculation load is reduced and the cost required for proper control is reduced. can be reduced.

実施形態の排気浄化システムを例示する構成図である。1 is a configuration diagram illustrating an exhaust purification system of an embodiment; FIG. 図１の排気浄化システムにおいて時刻の経過に伴う触媒装置の温度の変化を例示する変化図である。FIG. 2 is a change diagram illustrating changes in temperature of a catalytic device over time in the exhaust gas purification system of FIG. 1 ; 図１の加熱装置の出力電力と加熱装置を通過する排気の流量との関係を例示する関係図である。2 is a relationship diagram illustrating the relationship between the output power of the heating device of FIG. 1 and the flow rate of exhaust gas passing through the heating device; FIG. 実施形態の排気浄化システムの制御方法を例示するフロー図である。FIG. 2 is a flow diagram illustrating a control method for the exhaust gas purification system of the embodiment;

以下に、本開示における排気浄化システムおよびその制御方法の実施形態について説明する。図中において、白抜き矢印は吸気または空気の流れを示し、塗り潰し矢印は排気の流れを示し、一点鎖線は信号線を示す。なお、本実施形態において、吸気は内燃機関１の気筒に吸入される気体であり、空気に排気が混合されたものを含むものとする。 Embodiments of an exhaust purification system and a control method thereof according to the present disclosure will be described below. In the figure, white arrows indicate the flow of intake air or air, solid arrows indicate the flow of exhaust air, and dashed-dotted lines indicate signal lines. In the present embodiment, the intake air is gas taken into the cylinders of the internal combustion engine 1 and includes air mixed with exhaust gas.

図１に例示するように、本実施形態の排気浄化システム１０は車両の内燃機関１から燃料の燃焼により生じた排気が流通する排気通路２の中途位置に配置されて、排気を浄化するものである。内燃機関１は排出された排気が通過する排気通路２と、吸入される吸気が通過する吸気通路３と燃料の燃焼により得られた動力を出力するクランクシャフト４とを備えて構成される。なお、排気浄化システム１０は車両に搭載される内燃機関１に限定されない。 As shown in FIG. 1, an exhaust purification system 10 of the present embodiment is disposed in the middle of an exhaust passage 2 through which exhaust gas generated by combustion of fuel from an internal combustion engine 1 of a vehicle flows, and purifies the exhaust gas. be. An internal combustion engine 1 comprises an exhaust passage 2 through which discharged exhaust gas passes, an intake passage 3 through which intake air passes, and a crankshaft 4 for outputting power obtained by combustion of fuel. Note that the exhaust purification system 10 is not limited to the internal combustion engine 1 mounted on a vehicle.

排気浄化システム１０は、排気通路２の中途位置に配置されて、排気管燃料噴射装置１１、酸化触媒装置１２、フィルタ装置１３、還元剤噴射装置１４、選択的還元触媒装置１５、および、還元剤吸着触媒装置１６を備える。 The exhaust purification system 10 is arranged in the middle of the exhaust passage 2, and includes an exhaust pipe fuel injection device 11, an oxidation catalyst device 12, a filter device 13, a reducing agent injection device 14, a selective reduction catalyst device 15, and a reducing agent. An adsorption catalyst device 16 is provided.

排気管燃料噴射装置１１は排気の流れに関して酸化触媒装置１２の上流側に配置されて、排気通路２に未然の燃料を噴射する。酸化触媒装置１２は排気の流れに関してフィルタ装置１３の上流側に配置されて、排気に含有する炭化水素、一酸化炭素、及び一酸化窒素を酸化する触媒を有する。フィルタ装置１３は排気に含有する粒子状物質を捕集する。還元剤噴射装置１４は排気の流れに関して選択的還元触媒装置１５の上流側に配置されて、尿素水を噴射して選択的還元触媒装置１５に還元剤であるアンモニアを供給する。選択的還元触媒装置１５は排気の流れに関して還元剤吸着触媒装置１６の上流側に配置されて、アンモニアを還元剤として排気に含有する窒素酸化物を還元浄化する触媒を有する。還元剤吸着触媒装置１６は選択的還元触媒装置１５を通過後の排気に含まれる還元剤を吸着除去する触媒を有するとともにアンモニアを還元剤として排気に含有する窒素酸化物を還元浄化する触媒も有する。排気浄化システム１０は排気管燃料噴射装置１１を備えない代わりに、内燃機関１の図示しない燃料噴射装置のポスト噴射により酸化触媒装置１２に未然燃料を供給する構成にしてもよい。 The exhaust pipe fuel injection device 11 is arranged on the upstream side of the oxidation catalyst device 12 with respect to the flow of the exhaust gas, and injects fuel in advance into the exhaust passage 2 . The oxidation catalyst device 12 is arranged upstream of the filter device 13 with respect to the flow of exhaust gas and has a catalyst for oxidizing hydrocarbons, carbon monoxide and nitrogen monoxide contained in the exhaust gas. The filter device 13 collects particulate matter contained in the exhaust. The reducing agent injection device 14 is arranged upstream of the selective reduction catalyst device 15 with respect to the flow of exhaust gas, and injects urea water to supply the selective reduction catalyst device 15 with ammonia as a reducing agent. The selective reduction catalyst device 15 is arranged upstream of the reducing agent adsorption catalyst device 16 with respect to the flow of exhaust gas, and has a catalyst that reduces and purifies nitrogen oxides contained in the exhaust gas using ammonia as a reducing agent. The reducing agent adsorption catalyst device 16 has a catalyst that adsorbs and removes the reducing agent contained in the exhaust after passing through the selective reduction catalyst device 15, and also has a catalyst that reduces and purifies nitrogen oxides contained in the exhaust using ammonia as a reducing agent. . Instead of not including the exhaust pipe fuel injection device 11 , the exhaust gas purification system 10 may be configured to supply pre-fuel to the oxidation catalyst device 12 by post-injection of a fuel injection device (not shown) of the internal combustion engine 1 .

本開示において触媒装置とは排気に含有する窒素酸化物を浄化する触媒を有するものであり、本実施形態における選択的還元触媒装置１５および還元剤吸着触媒装置１６がその触媒装置に相当する。なお、還元剤吸着触媒装置１６がその触媒を有さない場合もあり、その場合に選択的還元触媒装置１５のみが触媒装置に相当する。また、本開示の触媒装置はアンモニアを還元剤として排気に含有する窒素酸化物を還元浄化する触媒を有する装置に限定されるものではない。触媒装置としては、排気中の窒素酸化物を排気がリーン状態のときに一旦吸蔵させ、排気がリッチ空燃比状態のときに吸蔵された窒素酸化物を放出させて、貴金属触媒の三元機能により還元する触媒を有するものでもよい。また、フィルタ装置１３が窒素酸化物を浄化する触媒を有し、粒子状物質の捕集と窒素酸化物の浄化との二つの機能を兼ね備える場合は、その窒素酸化物を浄化可能なフィルタ装置１３も触媒装置に相当する。 In the present disclosure, a catalyst device has a catalyst that purifies nitrogen oxides contained in exhaust gas, and the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 in this embodiment correspond to the catalyst device. Note that the reducing agent adsorption catalyst device 16 may not have the catalyst, and in that case only the selective reduction catalyst device 15 corresponds to the catalyst device. Further, the catalyst device of the present disclosure is not limited to a device having a catalyst that reduces and purifies nitrogen oxides contained in exhaust gas using ammonia as a reducing agent. As a catalytic device, when the exhaust gas is in a lean state, the nitrogen oxides in the exhaust gas are temporarily stored, and when the exhaust gas is in a rich air-fuel ratio state, the stored nitrogen oxides are released. It may have a reducing catalyst. Further, when the filter device 13 has a catalyst for purifying nitrogen oxides and has two functions of collecting particulate matter and purifying nitrogen oxides, the filter device 13 capable of purifying nitrogen oxides also corresponds to a catalytic device.

排気浄化システム１０は上記の構成に加えて、加熱装置２０と入口温度取得装置２１と出口温度取得装置２２とパラメータ取得装置として回転数取得装置２３および吸気量取得装置２４と電圧取得装置２５と制御装置３０と、を備えて構成される。 In addition to the above configuration, the exhaust purification system 10 includes a heating device 20, an inlet temperature acquisition device 21, an outlet temperature acquisition device 22, and a rotation speed acquisition device 23, an intake air amount acquisition device 24, and a voltage acquisition device 25 as parameter acquisition devices. a device 30;

加熱装置２０は排気の流れに関して選択的還元触媒装置１５よりも上流側で、かつ、フィルタ装置１３よりも下流側の排気通路２に配置される。より好ましくは、還元剤噴射装置１４よりも上流側の排気通路２に配置される。加熱装置２０が還元剤噴射装置１４よりも上流側の排気通路２に配置されることで、噴射された還元剤が付着することを回避するには有利となる。加熱装置２０としては自身を通過する空気を加熱する電気ヒータで構成され、バッテリ５にスイッチを介して接続される。このバッテリ５は内燃機関１の動力により発電する発電機６により充電されるとともに内燃機関１を始動させるスタータ７に電力を供給する。 The heating device 20 is arranged in the exhaust passage 2 upstream of the selective catalytic reduction device 15 and downstream of the filter device 13 with respect to the flow of exhaust gas. More preferably, it is arranged in the exhaust passage 2 on the upstream side of the reducing agent injection device 14 . Arranging the heating device 20 in the exhaust passage 2 on the upstream side of the reducing agent injection device 14 is advantageous in avoiding adhesion of the injected reducing agent. The heating device 20 is composed of an electric heater that heats the air passing through it, and is connected to the battery 5 via a switch. The battery 5 is charged by a generator 6 that generates power from the power of the internal combustion engine 1 and supplies power to a starter 7 that starts the internal combustion engine 1 .

入口温度取得装置２１は選択的還元触媒装置１５の入口を通過する排気の温度である入口温度Tｘを取得する装置である。入口温度取得装置２１は直に排気の温度を取得する温度センサで構成され、加熱装置２０と選択的還元触媒装置１５との間の排気通路２に配置される。 The inlet temperature acquisition device 21 is a device that acquires the inlet temperature Tx, which is the temperature of the exhaust gas passing through the inlet of the selective catalytic reduction device 15 . The inlet temperature acquisition device 21 is composed of a temperature sensor that directly acquires the temperature of the exhaust gas, and is arranged in the exhaust passage 2 between the heating device 20 and the selective catalytic reduction device 15 .

出口温度取得装置２２は還元剤吸着触媒装置１６の出口を通過する排気の温度である出口温度Ｔｙを取得する装置である。出口温度取得装置２２は直に排気の温度を取得する温度センサで構成され、排ガスの流れに関して還元剤吸着触媒装置１６より下流側の排気通路２に配置される。なお、前述したとおり還元剤吸着触媒装置１６が窒素酸化物を浄化する触媒を有しない場合に、出口温度取得装置２２は選択的還元触媒装置１５と還元剤吸着触媒装置１６との間に配置されることが望ましい。また、排気の流れに関して還元剤吸着触媒装置１６よりも下流側に弁装置や分岐通路が備えられる場合は、それらの装置よりも上流側に配置されることが望ましい。 The outlet temperature acquisition device 22 is a device that acquires the outlet temperature Ty, which is the temperature of the exhaust gas passing through the outlet of the reducing agent adsorption catalyst device 16 . The outlet temperature acquisition device 22 is composed of a temperature sensor that directly acquires the temperature of the exhaust gas, and is arranged in the exhaust passage 2 on the downstream side of the reducing agent adsorption catalyst device 16 with respect to the flow of the exhaust gas. As described above, when the reducing agent adsorption catalyst device 16 does not have a catalyst for purifying nitrogen oxides, the outlet temperature acquiring device 22 is arranged between the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16. preferably Further, if a valve device or a branch passage is provided downstream of the reducing agent adsorption catalyst device 16 with respect to the flow of exhaust gas, it is desirable to arrange them upstream of these devices.

回転数取得装置２３および吸気量取得装置２４は加熱装置２０を通過する排気の流量Ｑｇに関するパラメータを取得するパラメータ取得装置である。回転数取得装置２３は内燃機関１のクランクシャフト４の回転数Ｎｅを取得する装置である。吸気量取得装置２４は吸気通路３の吸気量Ｑｘを取得する装置である。本実施形態において、パラメータ取得装置は取得したパラメータに基づいて加熱装置２０を通過する排気の流量Ｑｇを取得可能な装置であればよく、回転数取得装置２３および吸気量取得装置２４に限定されない。例えば、パラメータ取得装置としては加熱装置２０を通過する排気の流量を直に取得する流量取得装置で構成されてもよい。 The rotational speed acquiring device 23 and the intake air amount acquiring device 24 are parameter acquiring devices for acquiring parameters relating to the flow rate Qg of exhaust gas passing through the heating device 20 . The rotation speed acquiring device 23 is a device for acquiring the rotation speed Ne of the crankshaft 4 of the internal combustion engine 1 . The intake air amount acquisition device 24 is a device that acquires the intake air amount Qx of the intake passage 3 . In this embodiment, the parameter acquisition device is not limited to the rotation speed acquisition device 23 and the intake air amount acquisition device 24 as long as it can acquire the flow rate Qg of the exhaust gas passing through the heating device 20 based on the acquired parameters. For example, the parameter acquisition device may be a flow rate acquisition device that directly acquires the flow rate of exhaust gas passing through the heating device 20 .

電圧取得装置２５は加熱装置２０へ電力を供給するバッテリ５の電圧Ｖｘを取得する装置である。電圧取得装置２５はバッテリ５の電圧Ｖｘを直に取得する装置に限定されずに、バッテリ５の電圧Ｖｘを間接的に取得する装置でもよい。例えば、電圧取得装置２５は発電機６からバッテリ５への発電状態を監視する装置でもよい。 The voltage acquisition device 25 is a device that acquires the voltage Vx of the battery 5 that supplies power to the heating device 20 . The voltage acquisition device 25 is not limited to a device that acquires the voltage Vx of the battery 5 directly, and may be a device that indirectly acquires the voltage Vx of the battery 5 . For example, the voltage acquisition device 25 may be a device that monitors the state of power generation from the generator 6 to the battery 5 .

制御装置３０は排気浄化システム１０の制御を行う装置であり、排気管燃料噴射装置１１の未然燃料の噴射によるフィルタ装置１３の再生制御や還元剤噴射装置１４の還元剤の噴射制御に加えて、加熱装置２０の加熱を制御する。制御装置３０は信号線により排気管燃料噴射装置１１、還元剤噴射弁１４、加熱装置２０、および、各種取得装置に電気的に接続される。 The control device 30 is a device that controls the exhaust purification system 10, and in addition to regeneration control of the filter device 13 by injection of unburned fuel from the exhaust pipe fuel injection device 11 and injection control of reducing agent from the reducing agent injection device 14, Heating of the heating device 20 is controlled. The control device 30 is electrically connected to the exhaust pipe fuel injection device 11, the reducing agent injection valve 14, the heating device 20, and various acquisition devices by signal lines.

制御装置３０は各種情報処理を行う中央演算装置（ＣＰＵ）、その各種情報処理を行うために用いられるプログラムや情報処理結果を読み書き可能な内部記憶装置、及び各種インターフェースなどから構成されるハードウェアである。 The control device 30 is hardware composed of a central processing unit (CPU) that performs various types of information processing, an internal storage device capable of reading and writing programs used for performing the various types of information processing and information processing results, and various interfaces. be.

制御装置３０は、入口設定温度Ｔａと、出口設定温度Ｔｂと、設定流量Ｑａを示すアイドル回転数Ｎｉおよび最低吸入量Ｑｍと、設定電圧Ｖａとが予め内部記憶装置に設定される。また、制御装置３０は、機能要素として判定部３１および加熱制御部３２を有する。各機能要素は、プログラムとして内部記憶装置に記憶されていて、適時、中央演算装置により実行されている。なお、各機能要素としては、プログラムの他にそれぞれが独立して機能するプログラマブルコントローラ（ＰＬＣ）や電気回路で構成されてもよい。 In the control device 30, an inlet set temperature Ta, an outlet set temperature Tb, an idling speed Ni and a minimum suction amount Qm indicating a set flow rate Qa, and a set voltage Va are set in advance in an internal storage device. Further, the control device 30 has a determination section 31 and a heating control section 32 as functional elements. Each functional element is stored as a program in the internal storage device and executed by the central processing unit at appropriate times. Note that each functional element may be configured by a programmable controller (PLC) or an electric circuit that functions independently of the program.

図２に例示するように、選択的還元触媒装置１５および還元剤吸着触媒装置１６が活性化して、窒素酸化物を還元浄化する性能が十分に発揮される温度帯として下限温度Ｔｄと上限温度Ｔｕとが予め設定される。これらの下限温度Ｔｄと上限温度Ｔｕとは触媒の種類に応じて予め定められた固定値であり、選択的還元触媒装置１５や還元剤吸着触媒装置１６の実際の温度を示している。なお、本実施形態において選択的還元触媒装置１５や還元剤吸着触媒装置１６の実際の温度はそれぞれの装置の中心部の温度やそれぞれの装置における全域の温度のうちの最低温度を示すものとする。また、選択的還元触媒装置１５および還元剤吸着触媒装置１６は下限温度Ｔｄよりも低い温度や上限温度Ｔｕよりも高い温度で窒素酸化物を全く還元浄化できないわけではない。 As illustrated in FIG. 2, the lower limit temperature Td and the upper limit temperature Tu are temperature ranges in which the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 are activated and the performance of reducing and purifying nitrogen oxides is sufficiently exhibited. are set in advance. These lower limit temperature Td and upper limit temperature Tu are fixed values predetermined according to the type of catalyst, and indicate the actual temperatures of the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 . In the present embodiment, the actual temperature of the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 indicates the lowest temperature among the temperature of the central part of each device and the temperature of the entire region of each device. . In addition, the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 cannot completely reduce and purify nitrogen oxides at a temperature lower than the lower limit temperature Td or higher than the upper limit temperature Tu.

入口設定温度Ｔａおよび出口設定温度Ｔｂのそれぞれは触媒装置が活性化したことを判定可能な値に設定される。触媒装置が活性化したことを判定可能な値としては、下限温度Ｔｄと上限温度Ｔｕとの間の温度が例示される。入口設定温度Ｔａおよび出口設定温度Ｔｂのそれぞれが下限温度Ｔｄと上限温度Ｔｕとの間に設定されることで、選択的還元触媒装置１５や還元剤吸着触媒装置１６の昇温効果を見極めるには有利となる。なお、本実施形態において下限温度Ｔｄと上限温度Ｔｕとの間の温度とは、下限温度Ｔｄと上限温度Ｔｕとを含んでもよい。 Each of the set inlet temperature Ta and the set outlet temperature Tb is set to a value that enables determination of activation of the catalyst device. A temperature between the lower limit temperature Td and the upper limit temperature Tu is exemplified as a value by which it can be determined that the catalyst device has been activated. By setting each of the inlet set temperature Ta and the outlet set temperature Tb between the lower limit temperature Td and the upper limit temperature Tu, the effect of increasing the temperature of the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16 can be determined. be advantageous. In this embodiment, the temperature between the lower limit temperature Td and the upper limit temperature Tu may include the lower limit temperature Td and the upper limit temperature Tu.

また、入口設定温度Ｔａは出口設定温度Ｔｂよりも高い温度に設定される。選択的還元触媒装置１５や還元剤吸着触媒装置１６は排気が入口から出口に向かって流れるために入口側の温度が出口側の温度よりも高くなる傾向にある。そこで、入口設定温度Ｔａを出口設定温度Ｔｂよりも高い温度に設定することで、入口側の温度と出口側の温度との間に生じる温度差を考慮した加熱制御が可能となる。 Also, the inlet set temperature Ta is set to a temperature higher than the outlet set temperature Tb. In the selective reduction catalyst device 15 and the reducing agent adsorption catalyst device 16, the temperature on the inlet side tends to be higher than the temperature on the outlet side because the exhaust flows from the inlet to the outlet. Therefore, by setting the inlet set temperature Ta to a temperature higher than the outlet set temperature Tb, it is possible to perform heating control in consideration of the temperature difference between the inlet side temperature and the outlet side temperature.

本実施形態で、出口設定温度Ｔｂは下限温度Ｔｄに設定され、入口設定温度Ｔａは下限温度Ｔｄに触媒装置が十分に活性化した状態における入口温度Ｔｘと出口温度Ｔｙとの差分の平均値を加算した温度に設定される。なお、入口設定温度Ｔａと出口設定温度Ｔｂとの関係はこれに限定されずに、予め実験や試験、あるいはシミュレーションにより求まるものであり、排気浄化システム１０の構成、加熱装置２０の出力電力、内燃機関１の排気量などにより適宜設定可能である。 In this embodiment, the outlet set temperature Tb is set to the lower limit temperature Td, and the inlet set temperature Ta is the average value of the difference between the inlet temperature Tx and the outlet temperature Ty when the catalyst device is sufficiently activated to the lower limit temperature Td. The added temperature is set. Note that the relationship between the inlet set temperature Ta and the outlet set temperature Tb is not limited to this, and can be obtained in advance by experiments, tests, or simulations. It can be appropriately set depending on the displacement of the engine 1 or the like.

図３に例示するように、加熱装置２０の出力電力と加熱装置２０を通過する排気の流量Ｑｇとは正の相関となり、加熱装置２０の出力電力は加熱装置２０を通過する排気の流量Ｑｇの大小により設定可能な値が定められている。つまり、加熱装置２０の出力電力を大きくして加熱装置２０により触媒装置を迅速に昇温するには排気の流量を大きくする必要がある。 As illustrated in FIG. 3, the output power of the heating device 20 and the flow rate Qg of the exhaust gas passing through the heating device 20 have a positive correlation. The values that can be set are defined according to the size. In other words, in order to increase the output power of the heating device 20 and quickly raise the temperature of the catalyst device by the heating device 20, it is necessary to increase the flow rate of the exhaust gas.

本実施形態において、加熱装置２０の出力電力を最大値Ｐｍａｘにするには、排気の流量Ｑｇを設定流量Ｑａよりも多い状態にする必要がある。設定流量Ｑａは、回転数取得装置２３が取得する内燃機関１の回転数Ｎｅがアイドル回転数Ｎｉよりも多く、かつ、吸気量取得装置２４が取得する吸気量Ｑｘが内燃機関１において燃焼可能な最低吸入量Ｑｍよりも多い状態の流量である。 In the present embodiment, in order to set the output power of the heating device 20 to the maximum value Pmax, the flow rate Qg of the exhaust gas must be higher than the set flow rate Qa. The set flow rate Qa is set so that the rotation speed Ne of the internal combustion engine 1 obtained by the rotation speed obtaining device 23 is greater than the idle rotation speed Ni, and the intake air amount Qx obtained by the intake air amount obtaining device 24 is combustible in the internal combustion engine 1. This flow rate is greater than the minimum intake amount Qm.

設定電圧Ｖａは内燃機関１が始動して発電機６による発電が開始されたことを判定可能な値に設定される。バッテリ５の電圧Ｖｘは内燃機関１が始動して発電機６による発電が開始されてその発電機６で発電された電力が充電される状態になると、その設定電圧Ｖａ以上の電圧に確保される。設定電圧Ｖａはスタータ７が駆動可能な電圧に設定されることが好ましい。 The set voltage Va is set to a value at which it can be determined that the internal combustion engine 1 has started and the power generator 6 has started to generate electricity. When the internal combustion engine 1 starts and the generator 6 starts to generate electricity and the electric power generated by the generator 6 is charged, the voltage Vx of the battery 5 is secured to a voltage higher than the set voltage Va. . The set voltage Va is preferably set to a voltage at which the starter 7 can be driven.

判定部３１は入口温度取得装置２１、出口温度取得装置２２、回転数取得装置２３、吸気量取得装置２４、および、電圧取得装置２５のそれぞれが取得する取得値が入力されて、入力されたそれらの取得値に基づいて、加熱装置２０の駆動の有無を判定する機能要素である。具体的に、判定部３１はそれらの取得値と、予め設定された入口設定温度Ｔａ、出口設定温度Ｔｂ、アイドル回転数Ｎｉ、最低吸入量Ｑｍ、および、設定電圧Ｖａとを比較して加熱装置２０の駆動の有無を判定し、その判定結果を加熱制御部３２に出力する機能要素である。 The determining unit 31 receives values obtained by the inlet temperature obtaining device 21, the outlet temperature obtaining device 22, the rotational speed obtaining device 23, the intake air amount obtaining device 24, and the voltage obtaining device 25, and determines the obtained values. is a functional element that determines whether or not the heating device 20 is driven based on the acquired value of . Specifically, the determination unit 31 compares these obtained values with the preset inlet set temperature Ta, outlet set temperature Tb, idling speed Ni, minimum suction amount Qm, and set voltage Va to determine whether the heating device 20 is driven or not and outputs the determination result to the heating control unit 32 .

加熱制御部３２は判定部３１の判定結果が入力されて、その判定結果に基づいて加熱装置２０の駆動を制御する機能要素である。 The heating control unit 32 is a functional element that receives the determination result of the determination unit 31 and controls the driving of the heating device 20 based on the determination result.

図４に例示するように、本実施形態の排気浄化システム１０の制御方法を制御装置３０の機能として説明する。この制御方法はイグニッションキーがオンの状態になると開始され、イグニッションキーがオフの状態になると終了する。制御フローは所定の周期ごとに繰り返し行われ、リターンでスタートや前のステップに戻ると一周期が経過するものとする。 As illustrated in FIG. 4, the control method of the exhaust gas purification system 10 of the present embodiment will be described as the function of the control device 30. As shown in FIG. This control method starts when the ignition key is turned on and ends when the ignition key is turned off. It is assumed that the control flow is repeated at predetermined intervals, and that one cycle elapses when returning to the start or the previous step.

イグニッションキーがオンの状態になると、判定部３１は各取得装置（２１～２５）を介してそれぞれの取得値（入口温度Ｔｘ、出口温度Ｔｙ、回転数Ｎｅ、吸気量Ｑｘ、電圧Ｖｘ）を取得する（Ｓ１１０）。 When the ignition key is turned on, the determination unit 31 acquires each acquired value (inlet temperature Tx, outlet temperature Ty, rotation speed Ne, intake air amount Qx, voltage Vx) through each acquisition device (21 to 25). (S110).

ついで、判定部３１は取得した入口温度Ｔｘと出口温度Ｔｙとの基づいた加熱装置２０の駆動の有無の判定を行うための判定を行う。判定部３１は取得した回転数Ｎｅおよび吸気量Ｑｘに基づいて得られる加熱装置２０を通過する排気の流量Ｑｇが設定流量Ｑａよりも多いか否かを判定する（Ｓ１２０）。具体的に、このステップＳ１２０は、取得した回転数Ｎｅがアイドル回転数Ｎｉよりも多いか否かを判定するとともに取得した吸気量Ｑｘが最低吸入量Ｑｍよりも多いか否かを判定するステップである。また、判定部３１は取得した電圧Ｖｘが設定電圧Ｖａよりも大きいか否かを判定する（Ｓ１３０）。 Next, the determination unit 31 performs determination for determining whether or not the heating device 20 is driven based on the acquired inlet temperature Tx and outlet temperature Ty. The determination unit 31 determines whether or not the flow rate Qg of the exhaust gas passing through the heating device 20 obtained based on the acquired rotational speed Ne and intake air amount Qx is greater than the set flow rate Qa (S120). Specifically, this step S120 is a step of determining whether or not the obtained rotational speed Ne is greater than the idle rotational speed Ni, and also determining whether or not the obtained intake air amount Qx is greater than the minimum intake air amount Qm. be. Further, the determination unit 31 determines whether or not the acquired voltage Vx is higher than the set voltage Va (S130).

排気の流量Ｑｇが設定流量Ｑａよりも多いと判定し（Ｓ１２０：ＹＥＳ）、かつ、電圧Ｖｘが設定電圧Ｖａよりも大きいと判定すると（Ｓ１３０：ＹＥＳ）、判定部３１は入口温度Ｔｘと出口温度Ｔｙとの基づいた加熱装置２０の駆動の有無の判定を行う。一方、排気の流量Ｑｇが設定流量Ｑａ以下と判定する（Ｓ１２０：ＮＯ）、または、電圧Ｖｘが設定電圧Ｖａ以下と判定すると（Ｓ１３０：ＮＯ）、判定部３１は加熱装置２０の駆動を停止するという判定結果を加熱制御部３２に送る。ついで、加熱制御部３２がその判定結果に基づいて加熱装置２０の駆動を停止する（Ｓ１７０）。なお、このステップ１７０を行う際に加熱装置２０の駆動が停止している場合に、その停止が継続される。 When it is determined that the flow rate Qg of the exhaust gas is greater than the set flow rate Qa (S120: YES) and that the voltage Vx is greater than the set voltage Va (S130: YES), the determination unit 31 determines the inlet temperature Tx and the outlet temperature. Whether or not the heating device 20 is driven is determined based on Ty. On the other hand, if it is determined that the flow rate Qg of the exhaust gas is equal to or less than the set flow rate Qa (S120: NO), or if it is determined that the voltage Vx is equal to or less than the set voltage Va (S130: NO), the determination unit 31 stops driving the heating device 20. is sent to the heating control unit 32 . Next, the heating control unit 32 stops driving the heating device 20 based on the determination result (S170). If the heating device 20 is stopped when step 170 is performed, the stop is continued.

温度に基づいた加熱装置２０の駆動の有無の判定において、判定部３１は取得した出口温度Ｔｙが出口設定温度Ｔｂよりも低いか否かを判定する（Ｓ１４０）。判定部３１は出口温度Ｔｙが出口設定温度Ｔｂよりも低いと判定すると（Ｓ１４０：ＹＥＳ）、加熱装置２０を駆動するという判定結果を加熱制御部３２に送る。ついで、加熱制御部３２がその判定結果に基づいて加熱装置２０を駆動する（Ｓ１６０）。なお、このステップ１６０を行う際に加熱装置２０が駆動している場合に、その駆動が継続される。 In determining whether or not the heating device 20 is driven based on the temperature, the determination unit 31 determines whether the acquired outlet temperature Ty is lower than the outlet set temperature Tb (S140). When the determination unit 31 determines that the outlet temperature Ty is lower than the outlet set temperature Tb (S140: YES), it sends the determination result to the heating control unit 32 to drive the heating device 20 . Next, the heating control section 32 drives the heating device 20 based on the determination result (S160). If the heating device 20 is being driven when step 160 is performed, the driving is continued.

一方、判定部３１は出口温度Ｔｙが出口設定温度Ｔｂ以上と判定すると（Ｓ１４０：ＮＯ）、判定部３１は取得した入口温度Ｔｘが入口設定温度Ｔａよりも低いか否かを判定する（Ｓ１５０）。判定部３１は入口温度Ｔｘが入口設定温度Ｔａよりも低いと判定すると（Ｓ１５０：ＹＥＳ）、制御フローはスタートに戻る。このとき、加熱装置２０が駆動している場合はその駆動が維持され、加熱装置２０の駆動が停止している場合はその停止が維持される。 On the other hand, when the determination unit 31 determines that the outlet temperature Ty is equal to or higher than the outlet set temperature Tb (S140: NO), the determination unit 31 determines whether the acquired inlet temperature Tx is lower than the inlet set temperature Ta (S150). . When the determination unit 31 determines that the inlet temperature Tx is lower than the inlet set temperature Ta (S150: YES), the control flow returns to the start. At this time, when the heating device 20 is being driven, the driving is maintained, and when the driving of the heating device 20 is stopped, the stop is maintained.

一方、判定部３１は入口温度Ｔｘが入口設定温度Ｔａ以上と判定すると（Ｓ１５０：ＮＯ）、判定部３１は加熱装置２０の駆動を停止するという判定結果を加熱制御部３２に送る。ついで、加熱制御部３２がその判定結果に基づいて加熱装置２０の駆動を停止する（Ｓ１７０）。 On the other hand, when the determination unit 31 determines that the inlet temperature Tx is equal to or higher than the inlet set temperature Ta (S150: NO), the determination unit 31 sends the determination result to the heating control unit 32 to stop driving the heating device 20 . Next, the heating control unit 32 stops driving the heating device 20 based on the determination result (S170).

このように入口温度Ｔｘと出口温度Ｔｙとを用いた判定では、加熱装置２０の駆動が停止している状態で出口温度Ｔｙに基づいて加熱装置２０の駆動の有無が判定され、加熱装置２０が駆動している状態で入口温度Ｔｘに基づいて加熱装置２０の駆動の停止の有無が判定される。 Thus, in the determination using the inlet temperature Tx and the outlet temperature Ty, it is determined whether or not the heating device 20 is driven based on the outlet temperature Ty while the heating device 20 is not being driven. Whether the driving of the heating device 20 is stopped or not is determined based on the inlet temperature Tx while the heating device 20 is being driven.

以上のステップＳ１１０～Ｓ１７０はイグニッションキーがオフの状態になるまで、繰り返し行われる。 The above steps S110 to S170 are repeated until the ignition key is turned off.

図２に例示するように、本開示の制御方法による加熱装置２０による触媒装置の加熱は内燃機関１が冷間始動した直後に行われる。なお、本開示の制御方法による加熱装置２０の触媒装置の加熱は内燃機関１の燃料の噴射が停止して車両が減速しているときにも行われる。 As illustrated in FIG. 2, the heating of the catalyst device by the heating device 20 according to the control method of the present disclosure is performed immediately after the internal combustion engine 1 is cold started. The heating of the catalytic device by the heating device 20 according to the control method of the present disclosure is performed even when the fuel injection of the internal combustion engine 1 is stopped and the vehicle is decelerating.

図中では、点線の軌跡が本開示の制御方法を行わない、つまり、加熱装置２０を用いない状態の触媒装置の温度を示し、一点鎖線の軌跡が入口温度Ｔｘのみの判定で加熱装置２０の駆動の有無を判定した制御の触媒装置の温度を示し、実線の軌跡が本開示の制御方法による触媒装置の温度を示す。なお、触媒装置の温度は実験により求めたものであり、触媒装置の中心部の温度を示すものとする。 In the figure, the dashed-dotted locus indicates the temperature of the catalyst device when the control method of the present disclosure is not performed, that is, the heating device 20 is not used. The temperature of the catalytic device in the control that determined whether or not to drive is shown, and the locus of the solid line indicates the temperature of the catalytic device according to the control method of the present disclosure. Note that the temperature of the catalyst device is obtained by experiment, and indicates the temperature at the central portion of the catalyst device.

本開示の制御方法では、イグニッションキーがオンの状態になり内燃機関１が冷間始動すると、上記のステップが順に行われる。時刻ｔ１が経過するまでの間はステップＳ１２０およびステップＳ１３０の判定により温度に基づく加熱装置２０の駆動の有無の判定を行っていない期間である。時刻ｔ１になると、ステップＳ１２０およびステップＳ１３０の判定により温度に基づく加熱装置２０の駆動の有無の判定が許可されて、温度の判定により加熱装置２０の駆動により触媒装置の温度が昇温する。 In the control method of the present disclosure, when the ignition key is turned on and the internal combustion engine 1 is cold-started, the above steps are performed in sequence. Until the time t1 elapses, it is a period in which it is not determined whether or not the heating device 20 is driven based on the temperature by the determinations in steps S120 and S130. At time t1, determination of whether or not heating device 20 is driven based on temperature is permitted by the determinations in steps S120 and S130, and the temperature of the catalyst device is increased by driving heating device 20 based on the temperature determination.

本開示の制御方法では、時刻ｔ２になると触媒装置の温度が下限温度Ｔｄを超える。一方、入口温度Ｔｘのみの判定で加熱装置２０の駆動の有無を判定した制御では時刻ｔ３になるまで触媒装置の温度が下限温度Ｔｄを超えない。これは、入口温度Ｔｘが入口設定温度Ｔａを超える時刻が時刻ｔ１と時刻ｔ２との間にあり、入口温度Ｔｘのみの判定加熱装置２０の駆動の有無を判定した制御では触媒装置の温度が十分に昇温しないうちに加熱装置２０の駆動を停止してしまうからである。 In the control method of the present disclosure, the temperature of the catalytic converter exceeds the lower limit temperature Td at time t2. On the other hand, in the control that determines whether or not the heating device 20 is driven based only on the inlet temperature Tx, the temperature of the catalyst device does not exceed the lower limit temperature Td until time t3. This is because the time at which the inlet temperature Tx exceeds the inlet set temperature Ta is between the time t1 and the time t2, and the temperature of the catalyst device is sufficiently high in the control that determines whether or not the heating device 20 is driven based only on the inlet temperature Tx. This is because the driving of the heating device 20 is stopped before the temperature rises sufficiently.

以上のように、本開示の排気浄化システム１０は、触媒装置の入口温度Ｔｘに加えて出口温度Ｔｙを判定し、出口温度Ｔｙが出口設定温度Ｔｂより低い場合に触媒装置の昇温が不十分と判定する。また、出口温度Ｔｙが出口設定温度Ｔｂ以上となり加熱装置２０が駆動すると入口温度Ｔｘが入口設定温度Ｔａ以上の場合触媒装置が十分に昇温した状態と判定する。このように、排気浄化システム１０によれば、二つの温度に基づいて判定することで触媒装置の昇温状態を適切に見極めることができる。これにより、触媒装置に対する十分な昇温効果と加熱装置２０で消費されるエネルギーの低減とを両立することができる。 As described above, the exhaust gas purification system 10 of the present disclosure determines the outlet temperature Ty in addition to the inlet temperature Tx of the catalyst device, and when the outlet temperature Ty is lower than the outlet set temperature Tb, the catalyst device temperature rise is insufficient. I judge. When the outlet temperature Ty rises above the outlet set temperature Tb and the heating device 20 is driven, if the inlet temperature Tx is above the inlet set temperature Ta, it is determined that the temperature of the catalyst device has risen sufficiently. As described above, according to the exhaust purification system 10, it is possible to appropriately determine the temperature rise state of the catalyst device by making a determination based on two temperatures. As a result, both a sufficient temperature raising effect on the catalyst device and a reduction in the energy consumed by the heating device 20 can be achieved.

また、本開示の排気浄化システム１０は、入口温度Ｔｘと出口温度Ｔｙとの二つの温度を用いて、それぞれと予め設定された入口設定温度Ｔａと出口設定温度Ｔｂとを比較することで加熱装置２０の駆動の有無を判定する。このように、排気浄化システム１０によれば、温度の比較判定という簡易な判定方法を用いることで、触媒装置自体の温度を推定する方法やＰＩＤ制御を用いる方法に比して、計算負荷を低減するとともに制御の適正化に要するコストを低減することができる。 In addition, the exhaust gas purification system 10 of the present disclosure uses two temperatures, the inlet temperature Tx and the outlet temperature Ty, and compares them with the preset inlet set temperature Ta and outlet set temperature Tb. 20 is driven or not. As described above, according to the exhaust purification system 10, by using a simple judgment method of comparing and judging the temperature, the calculation load is reduced compared to the method of estimating the temperature of the catalyst device itself or the method of using PID control. At the same time, it is possible to reduce the cost required for proper control.

また、本開示の排気浄化システム１０は触媒装置の出口温度Ｔｙの上昇は入口温度Ｔｘの上昇よりも遅いことと、上昇した後の出口温度Ｔｙの変化は入口温度Ｔｘの変化よりも小さいことを利用している。つまり、排気浄化システム１０は加熱装置２０の駆動の開始を出口温度Ｔｙのみで判定し、その出口温度Ｔｙが出口設定温度Ｔｂ以上となり安定した後は加熱装置２０の駆動の停止を入口温度Ｔｘのみで判定する。これにより、触媒装置の昇温速度を確保しつつ、昇温後に迅速に加熱装置２０の駆動を停止することで電力の消費を抑制することができる。 In addition, the exhaust gas purification system 10 of the present disclosure is configured such that the increase in the outlet temperature Ty of the catalyst device is slower than the increase in the inlet temperature Tx, and the change in the outlet temperature Ty after the rise is smaller than the change in the inlet temperature Tx. We are using. In other words, the exhaust gas purification system 10 determines the start of driving the heating device 20 based only on the outlet temperature Ty, and stops driving the heating device 20 only on the inlet temperature Tx after the outlet temperature Ty becomes equal to or higher than the outlet set temperature Tb and stabilizes. to judge. As a result, power consumption can be suppressed by quickly stopping the driving of the heating device 20 after the temperature rise while ensuring the temperature rise rate of the catalyst device.

排気浄化システム１０は加熱装置２０の駆動の有無の判定において、入口温度Ｔｘと出口温度Ｔｙとを経時的に用いる。そのため、入口設定温度Ｔａと出口設定温度Ｔｂとの関係を、触媒装置が十分に活性化した状態における入口温度Ｔｘと出口温度Ｔｙとの差分の平均値に基づいて設定するとよい。具体的に、入口設定温度Ｔａを出口設定温度Ｔｂにその差分の平均値を加算した温度に設定することが望ましい。このように設定することで、触媒装置の昇温速度を確保しつつ、消費電力を削減するには有利になる。 The exhaust purification system 10 uses the inlet temperature Tx and the outlet temperature Ty over time in determining whether or not the heating device 20 is driven. Therefore, the relationship between the inlet set temperature Ta and the outlet set temperature Tb should be set based on the average value of the difference between the inlet temperature Tx and the outlet temperature Ty when the catalytic device is sufficiently activated. Specifically, it is desirable to set the inlet set temperature Ta to a temperature obtained by adding the average value of the difference to the outlet set temperature Tb. By setting in this way, it is advantageous to reduce the power consumption while ensuring the heating rate of the catalyst device.

加熱装置２０は排気通路２に配置されて自身を通過する排気を加熱する電気ヒータを例示したが、触媒装置を直に加熱する装置としてもよい。本開示の排気浄化システム１０は加熱装置が触媒装置を直に加熱する装置で構成されても適用可能である。 Although the heating device 20 is an electric heater that is arranged in the exhaust passage 2 and heats the exhaust gas passing through it, it may be a device that directly heats the catalytic device. The exhaust purification system 10 of the present disclosure can be applied even if the heating device is configured by a device that directly heats the catalytic device.

本実施形態において、入口温度取得装置２１として触媒装置の入口の近傍に配置された温度センサと、出口温度取得装置２２として触媒装置の出口の近傍に配置された温度センサとの二つの温度センサを用いたが、温度センサを触媒装置の入口の近傍にのみ配置する構成にしてもよい。出口温度Ｔｙは、入口温度Ｔｘ、排気の流量Ｑｇ、触媒装置の熱容量から推定可能である。そこで、出口温度取得装置２２は、それらの取得値から出口温度Ｔｙを推定する装置や制御装置３０の機能要素が例示される。なお、触媒装置の温度を推定する方法は触媒装置の全域の温度や触媒装置の中心部の温度を推定するものであり、出口温度Ｔｙを推定する方法と比して計算が複雑であることはいうまでもない。 In this embodiment, two temperature sensors are used: a temperature sensor arranged near the inlet of the catalytic converter as the inlet temperature acquiring device 21 and a temperature sensor arranged near the outlet of the catalytic converter as the outlet temperature acquiring device 22. Although used, the temperature sensor may be arranged only in the vicinity of the inlet of the catalytic converter. The outlet temperature Ty can be estimated from the inlet temperature Tx, the exhaust gas flow rate Qg, and the heat capacity of the catalyst device. Therefore, the outlet temperature acquiring device 22 is exemplified by a device for estimating the outlet temperature Ty from the acquired values and a functional element of the control device 30 . The method of estimating the temperature of the catalytic converter estimates the temperature of the entire catalytic converter and the temperature of the central part of the catalytic converter, and the calculation is more complicated than the method of estimating the outlet temperature Ty. Needless to say.

本実施形態において、触媒装置が活性化したことを判定可能な値として還元剤噴射装置１４の噴射の有無を判定する噴射判定温度Ｔｎに基づいた温度を用いてもよい。噴射判定温度Ｔｎは還元剤である尿素水が十分に加水分解する温度を判定可能な温度である。この場合に、出口設定温度Ｔｂが噴射判定温度Ｔｎの近傍の値に設定され、入口設定温度Ｔａがその噴射判定温度Ｔｎの近傍の値よりも高い下限温度Ｔｄの近傍の値に設定される。 In the present embodiment, a temperature based on the injection determination temperature Tn for determining whether or not the reducing agent injection device 14 is injecting may be used as a value for determining that the catalytic device has been activated. The injection determination temperature Tn is a temperature at which the urea water, which is a reducing agent, can be sufficiently hydrolyzed. In this case, the outlet set temperature Tb is set to a value near the injection determination temperature Tn, and the inlet set temperature Ta is set to a value near the lower limit temperature Td, which is higher than the value near the injection determination temperature Tn.

本実施形態において、制御フローにおいて加熱装置２０を駆動した場合にフラグを立てるステップと、加熱装置２０の駆動を停止した場合にフラグを降ろすステップとを追加してもよい。つまり、フラグが立った場合に出口温度Ｔｙと出口設定温度Ｔｂとの比較判定を行い、フラグが降りた場合に入口温度Ｔｘと入口設定温度Ｔａとの比較判定を行うように構成してもよい。また、制御フローにおいて加熱装置２０を駆動する制御フローと、加熱装置２０の駆動を停止する制御フローとを別々にしてもよい。 In the present embodiment, a step of setting a flag when the heating device 20 is driven and a step of clearing the flag when the heating device 20 is stopped may be added to the control flow. That is, when the flag is raised, the outlet temperature Ty and the outlet set temperature Tb are compared and determined, and when the flag is lowered, the inlet temperature Tx and the inlet set temperature Ta are compared and determined. . Further, the control flow for driving the heating device 20 and the control flow for stopping the driving of the heating device 20 may be separate.

１０ 排気浄化システム
１５ 選択的還元触媒装置
１６ 還元剤吸着触媒装置
２０ 加熱装置
２１ 入口温度取得装置
２２ 出口温度取得装置
２３ 回転数取得装置
２４ 吸気量取得装置
２５ 電圧取得装置
３０ 制御装置
Ｔａ 入口設定温度
Ｔｂ 出口設定温度
Ｑａ 設定流量
Ｖａ 設定電圧 10 exhaust purification system 15 selective reduction catalyst device 16 reducing agent adsorption catalyst device 20 heating device 21 inlet temperature acquisition device 22 outlet temperature acquisition device 23 rotation speed acquisition device 24 intake air amount acquisition device 25 voltage acquisition device 30 control device Ta inlet set temperature Tb Outlet set temperature Qa Set flow rate Va Set voltage

Claims (7)

排気通路に配置された触媒装置と、バッテリからの電力の供給によりこの触媒装置を加熱する加熱装置と、を備える排気浄化システムにおいて、
前記触媒装置の入口を通過する排気の入口温度を取得する入口温度取得装置と、前記触媒装置の出口を通過する排気の出口温度を取得する出口温度取得装置と、前記加熱装置による加熱の駆動を制御する制御装置と、を備え、
前記制御装置に入口設定温度と出口設定温度とが予め設定されて、前記出口設定温度が、前記触媒装置が活性化したことを判定可能な値の中での下限を示す下限温度に設定されていて、前記入口設定温度が、前記触媒装置の入口側の温度と出口側の温度との間に生じる温度差に基づいて前記出口設定温度よりも高い温度に設定されていて、
前記制御装置は、前記加熱装置の駆動が停止している状態で前記出口温度取得装置が取得した前記出口温度が前記出口設定温度よりも低い場合に前記加熱装置を駆動し、前記加熱装置が駆動している状態で前記入口温度取得装置が取得した前記入口温度が前記入口設定温度以上の場合に前記加熱装置の駆動を停止する制御を行う構成であることを特徴とする排気浄化システム。 An exhaust gas purification system comprising a catalytic device arranged in an exhaust passage and a heating device that heats the catalytic device by electric power supplied from a battery ,
An inlet temperature acquiring device for acquiring an inlet temperature of exhaust gas passing through the inlet of the catalyst device, an outlet temperature acquiring device for acquiring an outlet temperature of exhaust gas passing through the outlet of the catalytic device, and driving of heating by the heating device. a control device for controlling,
An inlet set temperature and an outlet set temperature are set in advance in the control device, and the outlet set temperature is set to a lower limit temperature indicating a lower limit among values at which activation of the catalyst device can be determined. the inlet set temperature is set to a temperature higher than the outlet set temperature based on a temperature difference between the inlet side temperature and the outlet side temperature of the catalyst device,
The control device drives the heating device when the outlet temperature acquired by the outlet temperature acquisition device is lower than the outlet set temperature in a state where the heating device is not driven, and the heating device is driven. The exhaust gas purification system is configured to stop driving of the heating device when the inlet temperature acquired by the inlet temperature acquisition device is equal to or higher than the inlet set temperature. 前記制御装置は、前記出口温度が前記出口設定温度よりも低い場合に前記加熱装置を駆動し、前記出口温度が前記出口設定温度以上の場合に前記入口温度が前記入口設定温度以上のときに前記加熱装置の駆動を停止し、前記出口温度が前記出口設定温度以上の場合に前記入口温度が前記入口設定温度よりも低いときに前記加熱装置の駆動を維持する制御を行う構成である請求項１に記載の排気浄化システム。 The control device drives the heating device when the outlet temperature is lower than the outlet set temperature, and drives the heating device when the outlet temperature is higher than the outlet set temperature and when the inlet temperature is higher than the inlet set temperature. 2. A configuration in which driving of the heating device is stopped and control is performed to maintain driving of the heating device when the inlet temperature is lower than the inlet set temperature when the outlet temperature is equal to or higher than the outlet set temperature. The exhaust purification system described in . 前記触媒装置が還元剤噴射装置から噴射された還元剤を用いる選択的還元触媒装置であり、wherein the catalyst device is a selective reduction catalyst device using a reducing agent injected from a reducing agent injection device;
前記出口設定温度は、前記還元剤噴射装置の噴射の有無を判定する噴射判定温度の近傍の値に設定され、前記入口設定温度は、前記出口設定温度よりも高い前記下限温度の近傍の値に設定される請求項１または２に記載の排気浄化システム。The outlet set temperature is set to a value near the injection determination temperature for determining whether or not injection is to be performed by the reducing agent injection device, and the inlet set temperature is set to a value near the lower limit temperature higher than the outlet set temperature. 3. The exhaust gas purification system according to claim 1 or 2. 前記加熱装置は排気の流れに関して前記触媒装置の上流側の前記排気通路に配置されて通過する排気を加熱する構成であり、
前記加熱装置を通過する排気の流量に関するパラメータを取得するパラメータ取得装置を備え、
前記制御装置に設定流量が予め設定されて、
前記制御装置は前記パラメータ取得装置が取得したパラメータに基づいて得られた前記加熱装置を通過する排気の流量が前記設定流量よりも多い場合に前記入口温度と前記出口温度とに基づいて前記加熱装置の駆動の有無を判定し、排気の流量が前記設定流量以下の場合に前記加熱装置の駆動を停止する制御を行う構成である請求項１～３のいずれか１項に記載の排気浄化システム。 The heating device is arranged in the exhaust passage on the upstream side of the catalyst device with respect to the flow of exhaust gas, and heats the passing exhaust gas,
A parameter acquisition device for acquiring a parameter related to the flow rate of the exhaust gas passing through the heating device,
A set flow rate is set in advance in the control device,
When the flow rate of the exhaust gas passing through the heating device obtained based on the parameters obtained by the parameter obtaining device is larger than the set flow rate, the control device controls the heating device based on the inlet temperature and the outlet temperature. 4. The exhaust purification system according to any one of claims 1 to 3, wherein control is performed to determine whether or not the heating device is driven, and to stop driving the heating device when the flow rate of the exhaust gas is equal to or less than the set flow rate. 前記加熱装置の出力と前記設定流量とが正の相関があり、前記設定流量は前記加熱装置により排気を加熱するときの出力の最大値に基づいて設定される請求項４に記載の排気浄化システム。 5. The exhaust purification system according to claim 4, wherein there is a positive correlation between the output of said heating device and said set flow rate, and said set flow rate is set based on the maximum value of the output when said heating device heats the exhaust gas. . 前記加熱装置へ電力を供給する前記バッテリの電圧を取得する電圧取得装置を備え、
前記制御装置に設定電圧が予め設定されて、
前記制御装置は前記電圧取得装置が取得した電圧が前記設定電圧よりも高い場合に前記入口温度と前記出口温度とに基づいて前記加熱装置の駆動の有無を判定し、取得した電圧が前記設定電圧以下の場合に前記加熱装置の駆動を停止する制御を行う構成である請求項１～４のいずれか１項に記載の排気浄化システム。 A voltage acquisition device for acquiring the voltage of the battery that supplies power to the heating device,
A set voltage is preset in the control device,
When the voltage acquired by the voltage acquisition device is higher than the set voltage, the control device determines whether or not the heating device is driven based on the inlet temperature and the outlet temperature, and determines whether the acquired voltage is the set voltage. The exhaust purification system according to any one of claims 1 to 4, wherein control is performed to stop driving the heating device in the following cases. 制御装置によりバッテリからの電力が供給されて触媒装置を加熱する加熱装置を制御する排気浄化システムの制御方法において、
前記制御装置に予め入口設定温度と出口設定温度とを設定しておき、前記出口設定温度が、前記触媒装置が活性化したことを判定可能な値の中での下限を示す下限温度に設定されていて、前記入口設定温度が、前記触媒装置の入口側の温度と出口側の温度との間に生じる温度差に基づいて前記出口設定温度よりも高い温度に設定されていて、
前記触媒装置の入口を通過する排気の入口温度を取得するとともに、前記触媒装置の出口を通過する排気の出口温度を取得し、
前記制御装置により、前記加熱装置の駆動が停止している状態で取得した前記出口温度が前記出口設定温度よりも低い場合に前記加熱装置を駆動し、前記加熱装置が駆動している状態で取得した前記入口温度が前記入口設定温度以上のときに前記加熱装置の駆動を停止することを特徴とする排気浄化システムの制御方法。 In a control method for an exhaust gas purification system for controlling a heating device that heats a catalytic device by being supplied with power from a battery by a control device ,
An inlet set temperature and an outlet set temperature are set in advance in the control device, and the outlet set temperature is set to a lower limit temperature indicating a lower limit among values capable of determining that the catalyst device is activated. wherein the inlet set temperature is set to a temperature higher than the outlet set temperature based on a temperature difference between the inlet-side temperature and the outlet-side temperature of the catalyst device,
Acquiring the inlet temperature of the exhaust gas passing through the inlet of the catalyst device and acquiring the outlet temperature of the exhaust gas passing through the outlet of the catalyst device,
The control device drives the heating device when the outlet temperature obtained while the heating device is not driven is lower than the outlet set temperature, and obtains the temperature while the heating device is being driven. and stopping the driving of the heating device when the inlet temperature is equal to or higher than the inlet set temperature.
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