JPH0711946A - Exhaust emission control device for internal combustion engine - Google Patents
Exhaust emission control device for internal combustion engineInfo
- Publication number
- JPH0711946A JPH0711946A JP5159271A JP15927193A JPH0711946A JP H0711946 A JPH0711946 A JP H0711946A JP 5159271 A JP5159271 A JP 5159271A JP 15927193 A JP15927193 A JP 15927193A JP H0711946 A JPH0711946 A JP H0711946A
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- electrically heated
- deterioration
- energization
- electric heating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Exhaust Gas After Treatment (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、排気通路に電気加熱触
媒を備える内燃機関の排気浄化装置に関し、特に触媒金
属の劣化度合いに応じて触媒金属の排気浄化性能を最も
効率良く発揮させる技術に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification apparatus for an internal combustion engine having an electrically heated catalyst in an exhaust passage, and more particularly to a technique for maximizing the exhaust gas purification performance of a catalytic metal according to the degree of deterioration of the catalytic metal. .
【０００２】[0002]
【従来の技術】従来より、内燃機関の冷間始動時に排出
される有害排気成分（ＣＯ、ＨＣ、ＮＯX 等）を効率よ
く浄化するための内燃機関の排気浄化装置が提案されて
いる。例えば特開平３−２４６３１５号公報では、複数
の電気加熱触媒を排気の通路に直列に配置し、かつ電気
的にも直列に接続して各電気加熱触媒に通電する排気浄
化装置が開示されている。2. Description of the Related Art Conventionally, there has been proposed an exhaust gas purifying apparatus for an internal combustion engine for efficiently purifying harmful exhaust components (CO, HC, NO x, etc.) discharged during cold starting of the internal combustion engine. For example, Japanese Unexamined Patent Publication No. 3-246315 discloses an exhaust gas purification device in which a plurality of electrically heated catalysts are arranged in series in an exhaust passage and are also electrically connected in series to energize each electrically heated catalyst. .
【０００３】かかる排気浄化装置では、エンジンの冷却
水温を検出し、低温時に電気加熱触媒に通電している。
また電気加熱触媒は、夫々電気的に直列に接続されてい
るので一様に加熱される。In such an exhaust emission control device, the temperature of the cooling water of the engine is detected and the electric heating catalyst is energized when the temperature is low.
Moreover, since the electrically heated catalysts are electrically connected in series, they are uniformly heated.
【０００４】[0004]
【発明が解決しようとする課題】ところで、触媒を昇温
させる要素には、電気加熱の要素を除いて排気熱による
ものと触媒の反応熱によるものとがあり、この２つの要
素は互いに関わっている。即ち、排気による暖機は排気
浄化装置の入口付近から進むので、それにつれてモノリ
ス型の触媒では、排気熱により入口付近に配設された上
流側の触媒から自己燃焼による反応が促進され、反応熱
により温度も高くなってくる。そしてこれにより下流側
の触媒の暖機も促進される。The elements for raising the temperature of the catalyst include those due to exhaust heat and those due to the reaction heat of the catalyst, except for the electric heating element. These two elements are related to each other. There is. That is, since warming up by exhaust proceeds from the vicinity of the inlet of the exhaust gas purification device, in the monolith type catalyst, the reaction due to self-combustion is promoted by the exhaust heat from the upstream catalyst disposed near the inlet and the reaction heat As a result, the temperature will rise. As a result, the warm-up of the downstream catalyst is also promoted.
【０００５】しかしそれだけ入口付近の触媒の劣化が進
行し、図６のパターンＣのように、劣化した入口付近の
触媒では、反応熱による昇温効果が小さくなり、温度が
上がり難くなる。そのため結果的に触媒全体の昇温が遅
れ、初期に比較して触媒の自己燃焼による効果が劣って
くる。従来の電気加熱触媒を用いた内燃機関の排気浄化
装置では、電気加熱により、劣化した触媒の昇温を早め
ることが可能となるが、劣化度合いが異なる各触媒を一
様に加熱しているので、必要以上の電力を消費すること
になる。However, the deterioration of the catalyst near the inlet progresses to that extent, and as shown in pattern C of FIG. 6, in the deteriorated catalyst near the inlet, the temperature rise effect due to the reaction heat becomes small, and the temperature becomes difficult to rise. As a result, the temperature rise of the entire catalyst is delayed, and the effect of the self-combustion of the catalyst is inferior to the initial stage. In an exhaust gas purification apparatus for an internal combustion engine using a conventional electrically heated catalyst, it is possible to accelerate the temperature rise of the deteriorated catalyst by electric heating, but since each catalyst having different deterioration degrees is heated uniformly. , Will consume more power than necessary.
【０００６】また、従来の電気加熱触媒への通電方法に
あっては、電気加熱触媒への通電を判断する指標がエン
ジンの冷却水温だけであり、通電もオン、オフ制御のみ
でエンジンの運転状態や触媒の劣化度合いによらず一様
であるため、電気加熱触媒の性能を発揮させるために必
要な電気エネルギーを最も効率良く供給することが出来
なかった。Further, in the conventional method for energizing the electrically heated catalyst, the only index for judging the energization to the electrically heated catalyst is the cooling water temperature of the engine, and the energization is performed only by the on / off control. Since it was uniform regardless of the degree of deterioration of the catalyst and the degree of deterioration of the catalyst, it was not possible to most efficiently supply the electric energy required to exhibit the performance of the electrically heated catalyst.
【０００７】例えば電気加熱触媒がエンジンから遠い場
所に設置されている場合や始動時の冷却水温が低い場合
等において、図６のパターンＡのように、上限設定温度
以上まで急激に昇温させると設定温度以上になった時点
で通電がオフして電力の供給が停止する。そこに急加速
等により暖機が十分行われていない排気が大量に流れて
くると、一旦昇温した電気加熱触媒が冷やされて設定温
度以下まで下がってしまうため、電気加熱をした効果が
無くなってしまい、供給した電気エネルギーも無駄にな
ってしまう。For example, when the electrically heated catalyst is installed in a place far from the engine or the temperature of the cooling water at the time of starting is low, when the temperature is rapidly raised to above the upper limit set temperature as shown in pattern A of FIG. When the temperature exceeds the set temperature, the power supply is turned off and the power supply is stopped. If there is a large amount of exhaust gas that has not been warmed up due to sudden acceleration, etc., it will cool the once-heated electric heating catalyst and reduce it to below the set temperature, so the effect of electric heating will disappear. And the supplied electric energy is wasted.
【０００８】したがって電気エネルギーを有効に使え、
かつ排気浄化を満足に行うためには、エンジン運転状態
に応じてバランスよく昇温させるパターンＢが最適なの
であるが、通電をオン、オフ制御して各触媒を一様に加
熱するだけでは、この要求昇温パターンＢ通りに昇温さ
せることは難しく、冷却水温及び劣化度合いに応じてう
まく供給電力量を調整してやらないと、電気加熱触媒の
要求昇温パターンＢから外れた形で昇温してしまい、触
媒金属の排気浄化性能を最も効率良く発揮させることが
出来ず、電気エネルギーを無駄に消費してしまうおそれ
がある。Therefore, the electric energy can be effectively used,
In addition, in order to satisfactorily perform exhaust gas purification, the pattern B in which the temperature is raised in a well-balanced manner according to the engine operating state is optimal. However, if the energization is turned on / off to uniformly heat each catalyst, It is difficult to raise the temperature according to the required temperature rise pattern B, and unless the power supply amount is properly adjusted according to the cooling water temperature and the degree of deterioration, the temperature is raised in a form deviating from the required temperature rise pattern B for the electrically heated catalyst. As a result, the exhaust gas purification performance of the catalytic metal cannot be exhibited most efficiently, and electric energy may be wasted.
【０００９】本発明はこのような従来の課題に鑑みてな
されたもので、内燃機関の運転状態及び電気加熱触媒の
劣化度合いに応じて必要な電気エネルギーを効率よく供
給して触媒金属の排気浄化性能を最も効率良く発揮させ
ることが可能な内燃機関の排気浄化装置を提供すること
を目的とする。The present invention has been made in view of the above-mentioned conventional problems, and efficiently supplies the necessary electric energy according to the operating state of the internal combustion engine and the degree of deterioration of the electrically heated catalyst to purify the exhaust gas of the catalyst metal. It is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine that can exhibit its performance most efficiently.
【００１０】[0010]
【課題を解決するための手段】このため本発明は、図１
に示すように、通電することにより発熱する担体に触媒
金属を担持させた電気加熱触媒を、排気流れ方向に複数
個直列に配置した内燃機関の排気浄化装置において、機
関の冷却水温を検出する冷却水温検出手段と、前記触媒
金属の劣化度合いを検出する劣化検出手段と、前記冷却
水温と触媒金属の劣化度合いとに応じて、各電気加熱触
媒毎に通電量を設定する通電量設定手段と、設定された
通電量に基づいて各電気加熱触媒毎に通電制御する制御
手段と、を備えるようにした。Therefore, the present invention is based on FIG.
As shown in Fig. 3, in an exhaust gas purification device for an internal combustion engine, in which a plurality of electrically heated catalysts in which a catalyst metal is carried on a carrier that generates heat when energized are arranged in series in the exhaust gas flow direction, cooling for detecting the cooling water temperature of the engine is performed. Water temperature detection means, deterioration detection means for detecting the degree of deterioration of the catalyst metal, depending on the cooling water temperature and the degree of deterioration of the catalyst metal, an energization amount setting means for setting an energization amount for each electrically heated catalyst, And a control means for controlling energization for each electrically heated catalyst based on the set energization amount.
【００１１】また前記複数の電気加熱触媒を車両の床下
に配設する場合は、前記通電量設定手段が、触媒金属の
劣化度合いが高くなるにしたがって、各電気加熱触媒へ
の通電量の配分率を排気通路の上流側の電気加熱触媒ほ
ど大きくするように設定するとよい。さらに前記複数の
電気加熱触媒を排気マニホールドに近接した位置に配設
する場合は、前記通電量設定手段が、触媒金属の劣化度
合いが高くなるにしたがって、各電気加熱触媒への通電
量の配分率を下流側に配置された電気加熱触媒ほど大き
くするように設定することもできる。When the plurality of electrically heated catalysts are arranged under the floor of the vehicle, the energization amount setting means distributes the amount of energization to each electrically heated catalyst as the degree of deterioration of the catalyst metal increases. Is preferably set to be larger for the electrically heated catalyst on the upstream side of the exhaust passage. Further, when arranging the plurality of electrically heated catalysts in a position close to the exhaust manifold, the energization amount setting means distributes the energized amount to each electrically heated catalyst as the degree of deterioration of the catalyst metal increases. Can be set to be larger for the electrically heated catalyst arranged on the downstream side.
【００１２】[0012]
【作用】上記の構成によれば、機関の冷却水温は冷却水
温検出手段により検出され、触媒金属の劣化度合いは劣
化検出手段により検出される。電気加熱触媒の活性化は
劣化するにつれて低下するが、通電量設定手段により各
電気加熱触媒毎に機関の冷却水温と触媒金属の劣化度合
いとに応じて電気加熱触媒への通電量が設定され、設定
された通電量に基づいて制御手段により各電気加熱触媒
毎に通電が制御されることにより、冷却水温及び触媒金
属の劣化度合いから推定される昇温パターンで各電気加
熱触媒を昇温させることが可能となり、エネルギー効率
も良くなる。According to the above construction, the cooling water temperature of the engine is detected by the cooling water temperature detecting means, and the deterioration degree of the catalyst metal is detected by the deterioration detecting means. The activation of the electrically heated catalyst decreases as it deteriorates, but the electricity amount setting means sets the amount of electricity to the electrically heated catalyst according to the cooling water temperature of the engine and the degree of deterioration of the catalyst metal for each electrically heated catalyst. The electric power is controlled for each electric heating catalyst by the control means based on the set electric current amount, so that each electric heating catalyst is heated in a temperature rising pattern estimated from the cooling water temperature and the degree of deterioration of the catalyst metal. It is possible and energy efficiency is improved.
【００１３】また、車両の床下に電気加熱触媒を配設す
る際には、通電量設定手段が、触媒金属の劣化度合いが
高くなるにしたがって、各電気加熱触媒への通電量の配
分率を排気通路の上流側の電気加熱触媒ほど大きくする
ように設定することにより、触媒金属の劣化は入口付近
の方が先に進行するので、劣化検出手段によって触媒の
劣化が検出された場合には、上流側に配置された電気加
熱触媒ほど通電量が多くなる。したがって劣化が進み、
触媒金属の浄化反応の反応熱による昇温効果が小さくな
った分は、通電量を大きくすることで補われ、当初目標
として要求される昇温パターンを触媒金属劣化後も維持
することが可能となる。When the electrically heated catalyst is arranged under the floor of the vehicle, the energization amount setting means exhausts the distribution ratio of the energized amount to each electrically heated catalyst as the degree of deterioration of the catalyst metal increases. By setting the electric heating catalyst so that it becomes larger on the upstream side of the passage, the deterioration of the catalyst metal progresses earlier near the inlet, so if the deterioration of the catalyst is detected by the deterioration detecting means, The closer to the side the electrically heated catalyst is, the larger the amount of electricity passed. Therefore, deterioration progresses,
The decrease in the temperature rise effect due to the reaction heat of the catalytic metal purification reaction is compensated for by increasing the amount of electricity, and it is possible to maintain the temperature rise pattern required as the initial target even after catalyst metal deterioration. Become.
【００１４】また、排気マニホールドに近接した位置に
電気加熱触媒を配設すると、始動直後であっても排気の
温度が高く、電気加熱触媒が上流側であるほど高温の排
気に曝されるため、この高い排気熱を受けて昇温する
が、それだけ劣化が速く進み、劣化度合いが大きくな
る。この場合には、通電量設定手段が触媒金属の劣化度
合いが高くなるにしたがって、各電気加熱触媒への通電
量の配分率を下流側に配置された電気加熱触媒ほど大き
くするように設定することにより、効率よく電気加熱触
媒を昇温させることができる。この場合、上流側の触媒
は、劣化後も高い排気熱によって早期に昇温するので、
下流側の触媒の昇温を妨げるようなことはない。Further, when the electrically heated catalyst is arranged in a position close to the exhaust manifold, the temperature of the exhaust gas is high even immediately after starting, and the upstream side of the electrically heated catalyst is exposed to the exhaust gas having a higher temperature. The temperature of the exhaust gas rises due to this high exhaust heat, but the deterioration proceeds faster and the degree of deterioration increases. In this case, the energization amount setting means sets the distribution ratio of the energization amount to each electric heating catalyst to be larger for the electric heating catalyst arranged on the downstream side as the degree of deterioration of the catalyst metal increases. Thus, the temperature of the electrically heated catalyst can be raised efficiently. In this case, since the catalyst on the upstream side is quickly heated by the high exhaust heat even after deterioration,
It does not hinder the temperature rise of the downstream catalyst.
【００１５】[0015]
【実施例】以下、本発明の実施例を図２〜６に基づいて
説明する。図２は本実施例の床下設置型の排気浄化装置
の構成を示す図である。この排気浄化装置では、エンジ
ン１からの排気通路２中に設置されたコンバータ容器３
がエンジン１から比較的遠い床下に設置されている。こ
のコンバータ容器３には、通電することにより発熱する
担体に触媒金属を担持させたモノリス型の３つの電気加
熱触媒４ａ、４ｂ、４ｃがエンジン１側から順次、排気
通路２に対して直列に配置されている。Embodiments of the present invention will be described below with reference to FIGS. FIG. 2 is a diagram showing the configuration of the underfloor type exhaust gas purification apparatus of this embodiment. In this exhaust gas purification device, the converter container 3 installed in the exhaust passage 2 from the engine 1
Is installed under the floor relatively far from the engine 1. In the converter container 3, three monolithic electrically heated catalysts 4a, 4b, 4c in which a catalyst metal is supported on a carrier that generates heat when energized are sequentially arranged in series with the exhaust passage 2 from the engine 1 side. Has been done.
【００１６】エンジン１には冷却水温Ｔｗを検出する水
温センサ５が付設され、電気加熱触媒４ｃには、内部温
度を検出する温度センサ６が付設されている。この水温
センサ５、温度センサ６の検出信号は通電制御回路７に
入力される。排気通路２の触媒上流及び下流に夫々酸素
センサ８ａ、８ｂを備え、上流側の酸素センサ８ａから
の信号に基づいて空燃比を理論空燃比となるように空燃
比フィードバック補正係数を設定してエンジンの燃料噴
射量をフィードバック制御する一方、下流側の酸素セン
サ８ｂからの信号に基づいて前記空燃比フィーバック補
正係数を補正するようにしたシステムでは、上流側の酸
素センサ８ａがエンジン１の排気マニホールドに近接し
た位置に付設され、下流側の酸素センサ８ｂが電気加熱
触媒の下流位置に付設され、酸素センサ８ａ ８ｂの検
出信号は通電制御回路７に入力される。本実施例では、
これらの酸素センサ８ａ、８ｂを触媒金属の劣化度合い
を検出する劣化検出手段として用いる。A water temperature sensor 5 for detecting the cooling water temperature Tw is attached to the engine 1, and a temperature sensor 6 for detecting the internal temperature is attached to the electrically heated catalyst 4c. Detection signals of the water temperature sensor 5 and the temperature sensor 6 are input to the energization control circuit 7. Oxygen sensors 8a and 8b are provided upstream and downstream of the catalyst in the exhaust passage 2, and an air-fuel ratio feedback correction coefficient is set so that the air-fuel ratio becomes a stoichiometric air-fuel ratio based on a signal from the upstream oxygen sensor 8a. In the system in which the fuel injection amount is controlled by feedback while the air-fuel ratio feedback correction coefficient is corrected based on the signal from the oxygen sensor 8b on the downstream side, the oxygen sensor 8a on the upstream side is used for the exhaust manifold of the engine 1. The oxygen sensor 8b on the downstream side is attached to the downstream side of the electrically heated catalyst, and the detection signals of the oxygen sensors 8a and 8b are input to the energization control circuit 7. In this embodiment,
These oxygen sensors 8a and 8b are used as deterioration detecting means for detecting the degree of deterioration of the catalytic metal.
【００１７】通電制御回路７には、夫々スイッチ９ａ、
９ｂ、９ｃ、バッテリ11からの入力をデューティ制御す
るデューティ比変更回路10ａ、10ｂ、10ｃが夫々電気加
熱触媒４ａ、４ｂ、４ｃ毎に電気加熱触媒４ａ、４ｂ、
４ｃとバッテリ11との間に介装されている。また通電制
御回路７内には、マイクロコンピュータ（以後、マイコ
ンと記す）12が内蔵され、マイコン12には、冷却水温検
出手段に相当する水温センサ５、温度センサ６、酸素セ
ンサ８ａ、８ｂによって検出された各検出信号が入力さ
れる。またマイコン12にはＲＯＭ、ＲＡＭ等が備えら
れ、ＲＯＭには冷却水温Ｔｗと後述する電気加熱触媒４
ａ〜４ｃの劣化係数Ｋcat とに基づいて通電デューティ
比（00〜FF）を予め定めた通電パターンマップが記憶さ
れ、ＲＡＭには、酸素センサ８ａ、８ｂの検出信号に基
づいて判定された電気加熱触媒の劣化係数Ｋcatが逐次
記憶される。そしてマイコン12は、後述するフローチャ
ートにしたがい、前記各センサからの検出信号に基づい
てスイッチ９ａ〜９ｃ、デューティ比変更回路10ａ〜10
ｃを夫々別個に制御する。The energization control circuit 7 includes a switch 9a and a switch 9a, respectively.
9b, 9c, duty ratio changing circuits 10a, 10b, 10c for duty-controlling the input from the battery 11 are provided with electric heating catalysts 4a, 4b, 4c, respectively.
It is interposed between 4c and the battery 11. Further, a microcomputer (hereinafter referred to as a microcomputer) 12 is built in the energization control circuit 7, and the microcomputer 12 detects by a water temperature sensor 5, a temperature sensor 6, and oxygen sensors 8a and 8b corresponding to cooling water temperature detecting means. The detected signals thus obtained are input. Further, the microcomputer 12 is provided with a ROM, a RAM, etc., and the ROM has a cooling water temperature Tw and an electric heating catalyst 4 described later.
energization duty ratio on the basis of the deterioration coefficient K cat of a~4c (00~FF) predetermined energization pattern map is stored, in can comprise RAM, an oxygen sensor 8a, it is determined based on the detection signal 8b electrical The deterioration coefficient K cat of the heating catalyst is sequentially stored. Then, the microcomputer 12 operates the switches 9a to 9c and the duty ratio changing circuits 10a to 10c based on the detection signals from the respective sensors according to a flow chart described later.
Control c separately.
【００１８】次に図３のフローチャートに基づいてマイ
コン12の動作を説明する。図示しないスタートスイッチ
がオフしている時、あるいはスタートスイッチがオンし
てステップ２で読み込んだ水温センサ５からのエンジン
１の始動時の冷却水温Ｔｗが所定値Ｔ１以上である時に
は、各スイッチ12ａ〜12ｃをオフしたまま、各電気加熱
触媒４ａ〜４ｃを加熱せずにステップ１、３からこのル
ーチンを終了する。Next, the operation of the microcomputer 12 will be described with reference to the flowchart of FIG. When a start switch (not shown) is turned off, or when the start switch is turned on and the cooling water temperature Tw at the time of starting the engine 1 from the water temperature sensor 5 read in step 2 is equal to or higher than a predetermined value T1, each switch 12a ... This routine is ended from Steps 1 and 3 without heating each of the electrically heated catalysts 4a to 4c while keeping 12c off.
【００１９】スタートスイッチがオンし、冷却水温Ｔｗ
が所定値Ｔ１未満である時にはステップ１→２→３→４
に進み、前回運転時の電気加熱触媒４ａ〜４ｃの劣化係
数Ｋ cat を、マイコン12に内蔵されたＲＡＭより読み込
む。尚、電気加熱触媒４ａ〜４ｃの劣化は、電気加熱触
媒４ａ〜４ｃの前後に設置された酸素センサ８ａ、８ｂ
の検出信号が夫々反転するその周期の差（時間差）又は
周期の比に基づいてトータル値として判定され、その値
に基づいて劣化係数Ｋcat が設定される。The start switch is turned on, and the cooling water temperature Tw
Is less than the predetermined value T1, steps 1 → 2 → 3 → 4
To the deterioration factor of the electrically heated catalysts 4a to 4c during the previous operation.
Number K catIs read from the RAM built in the microcomputer 12.
Mu. In addition, the deterioration of the electrically heated catalysts 4a to 4c is caused by the electrically heated catalyst.
Oxygen sensors 8a, 8b installed before and after the mediums 4a-4c
Of the detection signals of the
Determined as a total value based on the cycle ratio, and its value
Based on the deterioration coefficient KcatIs set.
【００２０】ステップ５では、冷却水温Ｔｗと劣化係数
Ｋcat に基づいてＲＯＭに記憶された通電パターンマッ
プより通電する対象である電気加熱触媒４ａ、４ｂ、４
ｃ、及び通電デューティ比を決定する。次にこの通電パ
ターンマップの設定方法を以下に説明する。通電パター
ンマップは、図４において、夫々電気加熱触媒４ａ、４
ｂ、４ｃに対応するように３枚のマップによって構成さ
れている。各マップは、冷却水温Ｔｗに基づいたｍ個の
格子、劣化係数Ｋcat に基づいたｎ個の格子によるｍ×
ｎの通電デューティ比のデータからなっており、各マッ
プ内の通電デューティ比のデータは00〜FFまでとなって
おり、それによりデューティ比が０〜100%まで変化す
る。また各マップの（ｍx 、ｎY ）点のデータは、比較
すると、 １枚目（電気加熱触媒４ａ）≧２枚目（電気加熱触媒４
ｂ）≧３枚目（電気加熱触媒４ｃ） となるように設定されている。In step 5, the electrically heated catalysts 4a, 4b, 4 to be energized from the energization pattern map stored in the ROM based on the cooling water temperature Tw and the deterioration coefficient Kcat.
c and the energization duty ratio are determined. Next, a method of setting this energization pattern map will be described below. The energization pattern map is shown in FIG. 4 as the electrically heated catalysts 4a and 4a, respectively.
It is composed of three maps corresponding to b and 4c. Each map has m grids based on the cooling water temperature Tw and m grids based on the deterioration coefficient K cat.
The data of the energization duty ratio of n, and the data of the energization duty ratio in each map are 00 to FF, whereby the duty ratio changes from 0 to 100%. In addition, the data at the ( mx , n Y ) points of each map are as follows: 1st sheet (electrically heated catalyst 4a) ≧ 2nd sheet (electrically heated catalyst 4)
b) ≧ 3rd sheet (electrically heated catalyst 4c).
【００２１】前述のように電気加熱触媒４ａ〜４ｃを昇
温させる要素としては、電気加熱、排気の暖機、触媒の
自己燃焼による反応熱の３つの要素があり、３つの要素
が夫々関わっている。電気加熱触媒４ａ〜４ｃが初期状
態の時、冷却水温Ｔｗが高ければ、排気熱も大きく、排
気熱によって触媒金属が温められると、触媒金属の自己
燃焼による反応熱も大きくなってくる。この作用は、エ
ンジン１に近い電気加熱触媒４ａの担体ほど大きいの
で、電気加熱触媒４ａには比較的少量の電力を供給し、
電気加熱触媒４ｂ、４ｃになるほど電力の供給量が大き
くなるように配分する。As described above, as elements for raising the temperature of the electrically heated catalysts 4a to 4c, there are three elements of electric heating, exhaust warm-up, and reaction heat due to self-combustion of the catalyst, and these three elements are related to each other. There is. When the electrically heated catalysts 4a to 4c are in the initial state, if the cooling water temperature Tw is high, the exhaust heat is large, and when the exhaust metal heats the catalytic metal, the reaction heat due to self-combustion of the catalytic metal also becomes large. Since this action is greater for the carrier of the electrically heated catalyst 4a closer to the engine 1, a relatively small amount of electric power is supplied to the electrically heated catalyst 4a,
The electric heating catalysts 4b and 4c are distributed so that the power supply amount increases.
【００２２】またエンジン排気量により設定条件は異な
るが、床下設置型の排気浄化装置では、電気加熱触媒４
ａ〜４ｃの設置位置がエンジン１から比較的遠くにある
ため、始動直後では冷却水温Ｔｗが低く、また排気通路
２の排気管が冷えている。そのため排気管に熱を奪わ
れ、排気熱による昇温効果は小さく、触媒金属の自己燃
焼による反応熱の昇温効果はさらに小さくなる。したが
って冷却水温Ｔｗが低い場合には、それだけ電気加熱の
昇温効果がより大きく要求され、３つの要素の昇温効果
が、 電気加熱＞触媒反応熱＞排気熱 となるように、それと共に通電対象を増やし、供給電力
も増えるようにマップ設定する。Although the setting conditions differ depending on the engine displacement, in the underfloor type exhaust gas purification device, the electrically heated catalyst 4 is used.
Since the installation positions of a to 4c are relatively far from the engine 1, the cooling water temperature Tw is low immediately after the start and the exhaust pipe of the exhaust passage 2 is cold. Therefore, heat is taken by the exhaust pipe, the effect of raising temperature by exhaust heat is small, and the effect of raising reaction heat by self-combustion of the catalyst metal is further reduced. Therefore, when the cooling water temperature Tw is low, the heating effect of electric heating is required to be larger, and the heating effects of the three elements are as follows: electric heating> catalytic reaction heat> exhaust heat. And set the map so that the power supply also increases.
【００２３】触媒金属の触媒性能が低下してくると触媒
金属の自己燃焼による反応熱も小さくなってくる。この
場合、触媒金属の劣化形態を考えるとエンジン１に近い
部分から低下してくることが分かっているので、前段で
ある電気加熱触媒４ａの触媒性能の低下がもっとも激し
く、前段の電気加熱触媒４ａから要求昇温から外れ、そ
の影響でその後段の電気加熱触媒４ｂ、４ｃの昇温も遅
れてくる。したがって触媒金属の反応熱による昇温効果
が低下してきた時には、低下した分を電気加熱で補うよ
うにする必要があり、劣化係数Ｋcat が大きくなるほど
前段の方の電力供給の配分を増やすようにマップ設定
し、さらに通電対象も増やすようにマップ設定する。こ
のステップ５が通電量設定手段に相当する。When the catalytic performance of the catalytic metal decreases, the reaction heat due to self-combustion of the catalytic metal also decreases. In this case, it is known that when the deterioration form of the catalyst metal is considered, the catalyst performance of the electric heating catalyst 4a, which is the former stage, is most severely deteriorated, because it is known that the catalytic performance of the former stage electric heating catalyst 4a is most severe. Therefore, the temperature rise deviates from the required temperature rise, and the temperature rise of the electric heating catalysts 4b and 4c in the subsequent stage is delayed due to the influence. Therefore, when the temperature raising effect due to the reaction heat of the catalyst metal is decreasing, it is necessary to compensate for the decreased amount by electric heating, and as the deterioration coefficient K cat increases, the distribution of power supply in the former stage is increased. Set the map, and set the map to increase the number of energized objects. This step 5 corresponds to the energization amount setting means.
【００２４】ステップ６では、通電を開始する。通電
は、デューティ比変更回路10ａ、10ｂ、10ｃでバッテリ
11からの通電電流をデューティ制御するようにして、電
気加熱触媒４ａ〜４ｃが全て図６の昇温パターンＢに沿
って昇温するように行われる。温度センサ６によって検
出された電熱加熱触媒４ｃの内部温度ＴＥには、内部温
度の上限値Ｔ２、下限値Ｔ３が予め設定されており、所
定時間が経過するまでの間、Ｔ３≦ＴＥ≦Ｔ２となるよ
うに制御される。In step 6, energization is started. Power is supplied to the battery by the duty ratio changing circuits 10a, 10b, 10c.
The electric current supplied from 11 is duty-controlled so that all the electrically heated catalysts 4a to 4c are heated according to the temperature rising pattern B of FIG. The internal temperature TE of the electrothermal heating catalyst 4c detected by the temperature sensor 6 is preset with an upper limit value T2 and a lower limit value T3 of the internal temperature, and T3 ≦ TE ≦ T2 until a predetermined time elapses. Controlled to be.
【００２５】即ち、ステップ７では、温度センサ６から
の検出信号により電気加熱触媒４ｃ内部温度ＴＥを読み
込んで上限値Ｔ２と比較する。そして上限値Ｔ２以下で
あれば、ステップ11に進んで所定時間が経過するまで待
ち、所定時間が経過したら、ステップ12に進んで通電を
終了させてこのルーチンを終了する。また所定時間が経
過するまでに、電熱加熱触媒４ｃの内部温度ＴＥが上が
ってＴＥ＞Ｔ２となった時にはステップ７→８に進み、
スイッチをオフして通電を終了させる。そして内部温度
ＴＥを読み込んで検出信号ＴＥを下限値Ｔ３と比較しな
がら所定時間が経過するまで待ち、所定時間が経過した
時にはステップ９でこのルーチンを終了し、所定時間が
経過するまでにＴＥ＜Ｔ３となった時には、再びステッ
プ６に戻って通電を開始する。That is, in step 7, the internal temperature TE of the electrically heated catalyst 4c is read by the detection signal from the temperature sensor 6 and compared with the upper limit value T2. If it is less than or equal to the upper limit value T2, the routine proceeds to step 11 and waits until a predetermined time elapses. When the predetermined time has elapsed, the routine proceeds to step 12 to end the energization and terminate this routine. Further, when the internal temperature TE of the electrothermal heating catalyst 4c rises to TE> T2 before the predetermined time elapses, the process proceeds to steps 7 → 8,
Turn off the switch to end energization. Then, the internal temperature TE is read, and the detection signal TE is compared with the lower limit value T3, and waits until a predetermined time elapses. When the predetermined time elapses, this routine is ended in step 9 and TE < When T3 is reached, the process returns to step 6 again to start energization.
【００２６】このステップ６〜12が制御手段に相当す
る。かかる構成によれば、エンジン１の始動時の冷却水
温Ｔｗが所定温度Ｔ１未満である時、通電パターンマッ
プを検索してエンジン１の始動時の冷却水温Ｔｗと電気
加熱触媒４ａ〜４ｃの劣化度合いに応じて、上流側ほど
電気加熱触媒４ａ〜４ｃへの通電量が多くなるように配
分率を設定し、各電気加熱触媒４ａ〜４ｃ毎に通電制御
することにより、各電気加熱触媒４ａ〜４ｃは、要求昇
温パターンＢに沿って昇温するので、触媒金属の触媒性
能が向上し、バッテリ11からの電気エネルギーを効率良
く消費させることができる。The steps 6 to 12 correspond to the control means. According to this configuration, when the cooling water temperature Tw at the time of starting the engine 1 is lower than the predetermined temperature T1, the energization pattern map is searched and the cooling water temperature Tw at the time of starting the engine 1 and the degree of deterioration of the electrically heated catalysts 4a to 4c. Accordingly, the distribution ratio is set so that the amount of electricity supplied to the electrically heated catalysts 4a to 4c increases toward the upstream side, and the electricity supply is controlled for each of the electrically heated catalysts 4a to 4c. Since the temperature rises along the required temperature rise pattern B, the catalytic performance of the catalytic metal is improved, and the electric energy from the battery 11 can be efficiently consumed.
【００２７】尚、本実施例では、床下設置型排気浄化装
置について説明したが、これに限らず、排気マニホール
ド設置型のものについても適用できる。図５は排気マニ
ホールド設置型排気浄化装置を示す図であり、床下設置
型のものと異なる構成は、コンバータ容器３がエンジン
１に比較的近い位置に設置されている点である。In this embodiment, the underfloor type exhaust gas purification device has been described, but the present invention is not limited to this, and an exhaust manifold type device can also be applied. FIG. 5 is a diagram showing an exhaust manifold-installed type exhaust gas purification device, and a configuration different from the underfloor-installed type exhaust gas purification device is that converter container 3 is installed at a position relatively close to engine 1.
【００２８】エンジン１の近くに電気加熱触媒４ａ〜４
ｃを設置する理由として、ブースタとしての役割をより
強く要求されることであり、エンジン１近傍に配置すれ
ば始動直後の低い排気温度で触媒が冷やされてしまうこ
とがない。排気マニホールド設置型では、電気加熱触媒
４ａ〜４ｃがエンジン１に比較的近い位置に配設されて
いるので、始動直後であっても排気温度が十分高く、床
下設置の場合に比較して排気熱の昇温効果が大きい。し
たがって３つの要素の昇温効果を比較すると、 排気熱＞触媒反応熱＞電気加熱 の順になり、電気加熱触媒４ａ〜４ｃが初期状態の時に
は、エンジン１の排気量によっては、電気加熱触媒４ａ
〜４ｃに通電する必要がない場合もある。Electrically heated catalysts 4a-4 near the engine 1
The reason for installing c is that the role as a booster is strongly required, and if it is arranged near the engine 1, the catalyst will not be cooled at a low exhaust temperature immediately after starting. In the exhaust manifold installed type, since the electrically heated catalysts 4a to 4c are arranged at positions relatively close to the engine 1, the exhaust temperature is sufficiently high even immediately after starting, and the exhaust heat is higher than that in the case of installation under the floor. The effect of increasing temperature is large. Therefore, comparing the temperature raising effects of the three elements, the order of exhaust heat> catalyst reaction heat> electric heating is obtained. When the electric heating catalysts 4a to 4c are in the initial state, the electric heating catalyst 4a may differ depending on the exhaust amount of the engine 1.
It may not be necessary to energize ~ 4c.
【００２９】但し、排気マニホールド設置型の場合、触
媒金属の劣化が床下設置型に比較して大きく、触媒金属
が劣化してきた時の昇温効果は以下のようになる。排気
熱＞電気加熱＞触媒反応熱したがって触媒金属の劣化が
前段部より進行してきた場合、前段部では触媒金属反応
熱による昇温効果が見込めないので、前段部に通電する
よりも、触媒反応が見込める後段部に、より多くの電力
を供給した方が効果的である。前段部は排気熱の効果が
大きく触媒金属の反応熱がなくてもある程度の昇温を確
保することが出来、後段の電気加熱触媒４ｂ、４ｃにそ
れほど悪影響を与えずにすむ。However, in the case of the exhaust manifold installation type, the deterioration of the catalyst metal is larger than that in the underfloor installation type, and the temperature raising effect when the catalyst metal deteriorates is as follows. Exhaust heat> Electric heating> Catalytic reaction heat Therefore, when deterioration of the catalyst metal progresses from the front part, the catalyst reaction reaction is more effective than energizing the front part because the temperature rise effect due to the catalyst metal reaction heat cannot be expected in the front part. It is more effective to supply more power to the expected latter part. The effect of exhaust heat is large in the front part, and it is possible to secure a certain temperature rise even without the reaction heat of the catalyst metal, and it is possible to prevent the rear-stage electrically heated catalysts 4b, 4c from being adversely affected.
【００３０】そこで排気マニホールド設置型の場合、通
電制御は床下設置型と同じように図３のフローチャート
にしたがって行われるが、各電気加熱触媒４ａ、４ｂ、
４ｃへの通電量の配分は床下設置型とは異なり、各マッ
プの（ｍx 、ｎY ）点のデータが、 １枚目（電気加熱触媒４ａ）≦２枚目（電気加熱触媒４
ｂ）≦３枚目（電気加熱触媒４ｃ） となるように設定される。このようにマップ設定するこ
とにより、冷却水温Ｔｗが下がるにしたがって、通電量
は前段の電気加熱触媒４ａから後段にいくほど増えてい
き、劣化係数Ｋcat については、劣化係数Ｋcat が大き
くなるほど、後段の担体への電力供給も多くなってく
る。Therefore, in the case of the exhaust manifold installed type, the energization control is performed according to the flow chart of FIG. 3 similarly to the underfloor installed type, but the electric heating catalysts 4a, 4b,
The distribution of the amount of electricity supplied to 4c is different from the underfloor installation type, and the data at the ( mx , n Y ) point of each map is the first sheet (electric heating catalyst 4a) ≤ the second sheet (electric heating catalyst 4
b) ≦ 3rd sheet (electrically heated catalyst 4c) is set. By this way the map set according to the coolant temperature Tw decreases, the energization amount is incremented from the previous electric heating catalyst 4a toward the rear stage, the deterioration coefficient K cat, the greater the deterioration coefficient K cat, The power supply to the carrier in the latter stage also increases.
【００３１】[0031]
【発明の効果】以上説明したように本発明によれば、内
燃機関の冷却水温と各電気加熱触媒の劣化度合いに応じ
て電気加熱触媒への通電量の配分率を設定し、各電気加
熱触媒毎に通電制御することにより、各電気加熱触媒の
触媒金属の触媒性能が向上し、電気エネルギーを効率良
く消費させることができる。As described above, according to the present invention, the distribution ratio of the energization amount to the electric heating catalyst is set according to the cooling water temperature of the internal combustion engine and the degree of deterioration of the electric heating catalyst. By controlling the energization for each, the catalytic performance of the catalytic metal of each electrically heated catalyst is improved, and the electric energy can be efficiently consumed.
【００３２】また、触媒金属の劣化度合いが高くなるに
したがって、各電気加熱触媒への通電量の配分率が排気
流路の上流側の電気加熱触媒ほど大きくなるように制御
することにより、各電気加熱触媒の触媒性能を効率よく
発揮させることが出来る。また、複数の電気加熱触媒を
排気マニホールドに近接した位置に設けた場合には、触
媒金属の劣化度合いが高くなるにしたがって、各電気加
熱触媒への通電量の配分率が下流側に配置された電気加
熱触媒ほど大きくなるように制御することにより、各電
気加熱触媒の触媒性能を効率よく発揮させることが出来
る。Further, as the degree of deterioration of the catalyst metal increases, the distribution ratio of the amount of electricity supplied to each electric heating catalyst is controlled to become larger as the electric heating catalyst on the upstream side of the exhaust flow path, so that each electric heating catalyst is controlled. The catalytic performance of the heating catalyst can be efficiently exhibited. Further, when a plurality of electrically heated catalysts were provided in the vicinity of the exhaust manifold, the distribution ratio of the amount of electricity to each electrically heated catalyst was arranged on the downstream side as the degree of deterioration of the catalyst metal increased. By controlling the electric heating catalyst so that it becomes larger, the catalytic performance of each electric heating catalyst can be efficiently exhibited.
【図１】本発明の構成を示す機能ブロック図。FIG. 1 is a functional block diagram showing the configuration of the present invention.
【図２】本実施例の床下設置型排気浄化装置を示す構成
図。FIG. 2 is a configuration diagram showing an underfloor type exhaust emission control device of the present embodiment.
【図３】本実施例の通電制御のフローチャート。FIG. 3 is a flowchart of energization control according to this embodiment.
【図４】本実施例の通電パターンマップ。FIG. 4 is an energization pattern map of this embodiment.
【図５】本実施例の排気マニホールド設置型排気浄化装
置を示す構成図。FIG. 5 is a configuration diagram showing an exhaust manifold-installed exhaust purification device of the present embodiment.
【図６】昇温パターンを示す図。FIG. 6 is a diagram showing a heating pattern.
１ エンジン ２ 排気通路 ３ コンバータ容器 ４ａ、４ｂ、４ｃ 電気加熱触媒 ５ 水温センサ ６ 温度センサ ７ 通電制御回路 ８ａ、８ｂ 酸素センサ ９ａ、９ｂ、９ｃ スイッチ 10ａ、10ｂ、10ｃ デューティ比変更回路 11 バッテリ 12 マイクロコンピュータ（マイコン） 1 engine 2 exhaust passage 3 converter container 4a, 4b, 4c electric heating catalyst 5 water temperature sensor 6 temperature sensor 7 energization control circuit 8a, 8b oxygen sensor 9a, 9b, 9c switch 10a, 10b, 10c duty ratio changing circuit 11 battery 12 micro Computer (microcomputer)
フロントページの続き (72)発明者 田山 彰 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内Front page continuation (72) Inventor Akira Tayama 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.
Claims (3)
属を担持させた電気加熱触媒を、排気流れ方向に複数個
直列に配置した内燃機関の排気浄化装置において、 機関の冷却水温を検出する冷却水温検出手段と、 前記触媒金属の劣化度合いを検出する劣化検出手段と、 前記冷却水温と触媒金属の劣化度合いとに応じて、各電
気加熱触媒毎に通電量を設定する通電量設定手段と、 設定された通電量に基づいて各電気加熱触媒毎に通電制
御する制御手段と、を備えたことを特徴とする内燃機関
の排気浄化装置。1. An exhaust gas purification apparatus for an internal combustion engine in which a plurality of electrically heated catalysts, each of which has a catalyst metal supported on a carrier which generates heat when energized, are arranged in series in the exhaust gas flow direction, and a cooling water temperature of the engine is detected. Water temperature detection means, deterioration detection means for detecting the degree of deterioration of the catalyst metal, depending on the cooling water temperature and the degree of deterioration of the catalyst metal, the amount of electricity setting means for setting the amount of electricity for each electrically heated catalyst, An exhaust emission control device for an internal combustion engine, comprising: a control unit that controls energization for each electrically heated catalyst based on a set energization amount.
設すると共に、前記通電量設定手段が、触媒金属の劣化
度合いが高くなるにしたがって、各電気加熱触媒への通
電量の配分率を排気通路の上流側の電気加熱触媒ほど大
きくするように設定することを特徴とする請求項１記載
の内燃機関の排気浄化装置。2. The plurality of electrically heated catalysts are arranged under the floor of the vehicle, and the energization amount setting means distributes the amount of energization to each electrically heated catalyst as the degree of deterioration of the catalyst metal increases. 2. The exhaust gas purifying apparatus for an internal combustion engine according to claim 1, wherein the value is set so as to be larger for the electrically heated catalyst on the upstream side of the exhaust passage.
ドに近接した位置に配設すると共に、 前記通電量設定手段が、触媒金属の劣化度合いが高くな
るにしたがって、各電気加熱触媒への通電量の配分率を
下流側に配置された電気加熱触媒ほど大きくするように
設定することを特徴とする請求項１記載の内燃機関の排
気浄化装置。3. The plurality of electrically heated catalysts are arranged at positions close to the exhaust manifold, and the energization amount setting means increases the energization amount to each electrically heated catalyst as the degree of deterioration of the catalyst metal increases. 2. The exhaust gas purification device for an internal combustion engine according to claim 1, wherein the distribution ratio is set to be larger for the electrically heated catalyst arranged on the downstream side.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5159271A JPH0711946A (en) | 1993-06-29 | 1993-06-29 | Exhaust emission control device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5159271A JPH0711946A (en) | 1993-06-29 | 1993-06-29 | Exhaust emission control device for internal combustion engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0711946A true JPH0711946A (en) | 1995-01-13 |
Family
ID=15690134
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5159271A Pending JPH0711946A (en) | 1993-06-29 | 1993-06-29 | Exhaust emission control device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0711946A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017101600A (en) * | 2015-12-02 | 2017-06-08 | 三菱自動車工業株式会社 | Control device for engine |
| JP2019512632A (en) * | 2016-03-02 | 2019-05-16 | ワットロー・エレクトリック・マニュファクチャリング・カンパニー | System and method for axial zoning of heating power |
-
1993
- 1993-06-29 JP JP5159271A patent/JPH0711946A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017101600A (en) * | 2015-12-02 | 2017-06-08 | 三菱自動車工業株式会社 | Control device for engine |
| JP2019512632A (en) * | 2016-03-02 | 2019-05-16 | ワットロー・エレクトリック・マニュファクチャリング・カンパニー | System and method for axial zoning of heating power |
| US11028759B2 (en) | 2016-03-02 | 2021-06-08 | Watlow Electric Manufacturing Company | System and method for axial zoning of heating power |
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