JPH0374561A - Exhaust gas purifying device for engine - Google Patents
Exhaust gas purifying device for engineInfo
- Publication number
- JPH0374561A JPH0374561A JP1209146A JP20914689A JPH0374561A JP H0374561 A JPH0374561 A JP H0374561A JP 1209146 A JP1209146 A JP 1209146A JP 20914689 A JP20914689 A JP 20914689A JP H0374561 A JPH0374561 A JP H0374561A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- engine
- egr
- purification catalyst
- nox
- 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.)
- Granted
Links
- 239000003054 catalyst Substances 0.000 claims abstract description 65
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 28
- 238000000746 purification Methods 0.000 claims description 86
- 239000007789 gas Substances 0.000 description 92
- 239000000446 fuel Substances 0.000 description 9
- 238000002485 combustion reaction Methods 0.000 description 7
- 239000010949 copper Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 239000002826 coolant Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000003134 recirculating effect Effects 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical group [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
Landscapes
- Exhaust-Gas Circulating Devices (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明はエンジンの排気ガス浄化装置の改良に関する。[Detailed description of the invention] (Industrial application field) The present invention relates to an improvement in an engine exhaust gas purification device.
（従来の技術）
近年の排気ガス浄化技術の進歩により大気中に放出され
るＨＣ及びＣＯの量は減少しているが、ＮＯｘに対する
対策が遅れているので、都市部を中心にしてＮＯｘに起
因する酸性雨が降る等の被害が発生している。(Conventional technology) Recent advances in exhaust gas purification technology have reduced the amount of HC and CO emitted into the atmosphere, but measures against NOx are lagging behind, so Damages such as acid rain are occurring.
もっとも、排気ガス中のＮＯｘを浄化できるものとして
ＮＨ３接触還元法が知られているが、このＮＨ３接触還
元法は、システムが複雑でコストが高い上に、燃焼ガス
温度が高い時にＮＨ，が排出されるという二次公害の問
題を有しているため、自動車に適用するには未解決の問
題が多い。However, the NH3 catalytic reduction method is known as a method that can purify NOx in exhaust gas, but this NH3 catalytic reduction method has a complicated system and high cost, and NH, is emitted when the combustion gas temperature is high. However, there are many unresolved problems in applying it to automobiles, as there is the problem of secondary pollution caused by air pollution.
これに対して、排気ガス中のＩＣ，Ｃｏ及びＮＯｘを１
つの触媒コンバータで同時に浄化できる三元触媒方式も
提案されているが、この三元触媒方式は理論空燃比付近
では効果的であるが、排気ガスの空燃比がリーン状態で
は浄化性能が不十分であるという問題がある。On the other hand, IC, Co and NOx in the exhaust gas are reduced to 1
A three-way catalytic system has also been proposed in which two catalytic converters can purify the air at the same time, but although this three-way catalytic system is effective near the stoichiometric air-fuel ratio, its purification performance is insufficient when the air-fuel ratio of exhaust gas is lean. There is a problem.
そこで、近時、特開昭６３−１００９１９号公報に示さ
れるように、酸化雰囲気中、ＨＣの存在下でＮＯｘを浄
化することができる触媒としてＣＵを含有するＮＯｘ浄
化触媒が提案されている。Therefore, as disclosed in Japanese Patent Application Laid-Open No. 63-100919, a NOx purification catalyst containing CU has been proposed as a catalyst capable of purifying NOx in the presence of HC in an oxidizing atmosphere.
（発明が解決しようとする課′ＸＪ）
しかるに、このＣｕを含有するＮＯｘ浄化触媒は、第８
図に示すように、触媒を通過する排気ガス温度によって
浄化性能が異なり、排気ガス温度が５００℃付近のとき
に浄化性能がピークで、この温度以上或いはこの温度以
下では浄化性能が低下するという問題がある。(Problem to be solved by the invention 'XJ) However, this NOx purification catalyst containing Cu is
As shown in the figure, the purification performance varies depending on the temperature of the exhaust gas passing through the catalyst, and the purification performance peaks when the exhaust gas temperature is around 500℃, and the problem is that the purification performance decreases above or below this temperature. There is.
そこで、本発明者は、排気ガスの温度が低い時と高い時
つまりエンジンの低負荷時と高負荷時に、ＥＧＲ装置を
作動させて排気ガスを吸気系へ還流させて排気ガス中に
排出されるＮＯｘの低減を図り、これにより前記ＮＯｘ
浄化触媒の浄化性能を捕うことを考慮した。Therefore, the present inventor operated the EGR device to recirculate the exhaust gas to the intake system when the exhaust gas temperature is low or high, that is, when the engine load is low or high, and the exhaust gas is discharged into the exhaust gas. The aim is to reduce NOx, thereby reducing the amount of NOx.
Consideration was given to capturing the purification performance of the purification catalyst.
ところが、このＥＧＲ装置を備えた排気ガス浄化装置に
よると、ＮＯｘ浄化触媒が十分に機能しない領域でＥＧ
Ｒ装置によってＮＯｘ浄化触媒の浄化能力を補うことは
できるが、エンジンの低負荷時には、低温の排気ガスが
還流する結果、エンジンの燃焼性が十分でないという問
題、及び、エンジンの高負荷時には、高温の排気ガスが
還流する結果、燃焼室における燃焼温度を十分に抑える
ことができないためＮＯｘの低減効果が十分でないとい
う問題が避けられなかった。However, according to the exhaust gas purification device equipped with this EGR device, the EGR
The R device can supplement the purification ability of the NOx purification catalyst, but when the engine is under low load, low-temperature exhaust gas recirculates, resulting in insufficient engine combustibility, and when the engine is under high load, high temperature As a result of the exhaust gas being recirculated, the combustion temperature in the combustion chamber cannot be sufficiently suppressed, so the problem of insufficient NOx reduction effect cannot be avoided.
前記に鑑み、本発明は、Ｃｕを含有するＮＯｘ浄化触媒
の浄化性能が低いエンジンの低負荷時及び高負荷時に、
ＥＧＲ装置によってＮＯｘ浄化性能を補いつつ、エンジ
ンの低負荷時にはエンジン燃焼性の向上を図ると共に、
エンジンの高負荷時にはＮＯｘ排出量の低減効果の向上
を図ることを目的とする。In view of the foregoing, the present invention provides a method for reducing the purification performance of the NOx purification catalyst containing Cu during low load and high load of the engine.
While supplementing NOx purification performance with the EGR device, it also aims to improve engine combustibility when the engine is under low load.
The purpose is to improve the effect of reducing NOx emissions when the engine is under high load.
（課題を解決するための手段）
前記の目的を達成するため、本発明は、エンジンの低負
荷時にはＮＯｘ浄化触媒通過前の高温状態の排気ガスを
還流させる一方、エンジンの高負荷時にはＮＯｘ浄化触
媒通過後の高比熱で低温状態の排気ガスを還流させるも
のである。(Means for Solving the Problems) In order to achieve the above object, the present invention recirculates high-temperature exhaust gas before passing through the NOx purification catalyst when the engine is under low load, while recirculating the high-temperature exhaust gas before passing through the NOx purification catalyst when the engine is under high load. After passing through, the exhaust gas is refluxed at a high specific heat and low temperature.
具体的に本発明の講じた解決手段は、エンジンの排気系
にＣｕを含有するＮＯｘ浄化触媒を備えたエンジンの排
気ガス浄化装置を前提とし、前記ＮＯｘ浄化触媒の上流
側及び下流側から排気ガスを取出して吸気系へ還流させ
ると共に、前記ＮＯｘ浄化触媒の上流側からの還流と下
流側からの還流とを切換えるＥＧＲ装置と、エンジンの
低負荷時には排気ガスを前記ＮＯｘ浄化触媒の上流側か
ら還流させる一方、エンジンの高負荷時には排気ガスを
前記ＮＯｘ浄化触媒の下流側から還流させるよう前記Ｅ
ＧＲ装置を制御するＥＧＲ制御手段とを備える構成とす
るものである。Specifically, the solution taken by the present invention is based on an engine exhaust gas purification device equipped with a NOx purification catalyst containing Cu in the engine exhaust system, and exhaust gas is removed from the upstream and downstream sides of the NOx purification catalyst. an EGR device that extracts and recirculates the exhaust gas to the intake system and switches between recirculation from the upstream side of the NOx purification catalyst and recirculation from the downstream side; and an EGR device that recirculates the exhaust gas from the upstream side of the NOx purification catalyst when the engine is under low load. On the other hand, when the engine is under high load, the E
The configuration includes an EGR control means for controlling the GR device.
（作用）
本発明の構成により、ＮＯｘ浄化触媒の浄化性能が低い
エンジンの低負荷時及び高負荷時においては、ＥＧＲ装
置によるＥＧＲによって排気ガス中に排出されるＮＯＸ
量を低減させることができる。(Function) According to the configuration of the present invention, NOx is emitted into the exhaust gas by EGR by the EGR device during low load and high load of the engine where the purification performance of the NOx purification catalyst is low.
The amount can be reduced.
また、エンジンの低負荷時には排気ガスをＮＯｘ浄化触
媒の上流側から取出すため、高温状態の排気ガスが吸気
系に還流する。Furthermore, when the engine is under low load, the exhaust gas is taken out from the upstream side of the NOx purification catalyst, so the high-temperature exhaust gas is returned to the intake system.
さらに、エンジンの高負荷時には排気ガスをＮＯｘ浄化
触媒の下流側から取出すので、比熱の高い排気ガスが吸
気系に還流することにより燃焼室の熱容量が高められる
と共に、ＮＯｘ浄化触媒を通過して低温状態になった排
気ガスが吸気系に還流する。Furthermore, when the engine is under high load, exhaust gas is extracted from the downstream side of the NOx purification catalyst, so the exhaust gas with high specific heat returns to the intake system, increasing the heat capacity of the combustion chamber, and passes through the NOx purification catalyst to a low temperature. Exhaust gas in this state is returned to the intake system.
（実施例） 以下、本発明の実施例を図面に基づいて説明する。(Example) Embodiments of the present invention will be described below based on the drawings.
第１図は、本発明の第１実施例に係るディーゼルエンジ
ンの排気ガス浄化装置がディーゼルエンジンＩＯＡに適
用された場合の全体構成を示し、同図において、１２は
ディーゼルエンジンＩＯＡにエアを吸入するための吸気
管、１４はディーゼルエンジンＩＯＡの各シリンダへエ
アを配給するインテークマニホールド、１５は前記各シ
リンダに燃料を噴射、供給する燃料噴射ポンプ、１６は
前記各シリンダから排出される排気ガスを集めるエキゾ
ーストマニホールド、１８は排気ガスを排出する排気管
である。FIG. 1 shows the overall configuration when the diesel engine exhaust gas purification device according to the first embodiment of the present invention is applied to a diesel engine IOA. 14 is an intake manifold that distributes air to each cylinder of the diesel engine IOA; 15 is a fuel injection pump that injects and supplies fuel to each cylinder; 16 is a collection of exhaust gas discharged from each cylinder; Exhaust manifold 18 is an exhaust pipe that discharges exhaust gas.
また、同図において、２０は排気ガス中のＮ。Further, in the figure, 20 is N in the exhaust gas.
×を還元するためのＣｕを含有するＮＯｘ浄化触媒であ
って、次のようにして製造される。すなわち、ゼオライ
トの一種であるモルデナイト［Ｎａ２０１ＡＩ２０３
＊ｎＳｉＯ２コのＮａがＨで置換され、Ｓ ｉ Ｏ：：
／Ａ １２０３のモル比が１０以上で、細孔径が７オ
ングストロ一ム程度のものを準備し、これを有機酸鋼の
水溶液に含浸させ、イオン交換を起こさせてＣｕを担持
させる。この場合、銅イオン交換率が多いものほどＮＯ
ｘの浄化率は高いと共に、Ｓ ｔｏ、２ ／Ａ １２０
３のモル比が高いほど触媒活性が高い。This is a NOx purification catalyst containing Cu for reducing x, and is manufactured as follows. That is, mordenite [Na201AI203, which is a type of zeolite]
*Na of nSiO2 is replaced with H, S i O::
/A1203 having a molar ratio of 10 or more and a pore diameter of about 7 angstroms is prepared, and this is impregnated with an aqueous solution of organic acid steel to cause ion exchange and support Cu. In this case, the higher the copper ion exchange rate, the more NO
The purification rate of x is high and S to,2 /A 120
The higher the molar ratio of 3, the higher the catalyst activity.
また、このＮＯＸ浄化触媒２０は、２Ｃｕ”＋ＮＯ−２
Ｃｕ２”＋Ｎ０−−”２Ｃｕ” ＋Ｎ２ ＋０２に示す
ような分解反応を行なうことにより、Ｎ。In addition, this NOx purification catalyst 20 has 2Cu"+NO-2
Cu2"+N0--"2Cu"+N2+02 By performing a decomposition reaction as shown in FIG.
をＮごと０２に分解するものであって、前記のように５
００℃前後でＮＯに対する高い浄化率を有していると共
に、他の触媒と比べてＮｏ分解性能がかなり高い。また
、このＮＯｘ浄化触媒２０は排気ガスの空燃比がリーン
雰囲気ではＮＯＸの浄化性能が高いが、０２分圧が高い
ほど浄化率が低下し、またＣ０分圧が低いほど浄化率が
低下するという性質を有している。is decomposed into 02 for each N, and as mentioned above, 5
It has a high NO purification rate at around 00°C, and has considerably higher NO decomposition performance than other catalysts. In addition, this NOx purification catalyst 20 has high NOx purification performance in an atmosphere where the air-fuel ratio of exhaust gas is lean, but the higher the 02 partial pressure, the lower the purification rate, and the lower the C0 partial pressure, the lower the purification rate. It has properties.
また、同図において、２１はＮＯｘ浄化触媒２０の上流
側の排気管１８に配設され、排気ガス中の微粒子を捕集
して濾過するＤＰＦ （ディーゼルパティキュレートフ
ィルター）、２２はＤＰＦ２１の上流側の排気管１８の
壁部に配設され、ＤＰＦ２１に付着した微粒子を燃焼さ
せるバーナーである。このように、ＮＯｘ浄化触媒２０
の上流側にＤＰＦ２１が配設されているため、排気ガス
中の微粒子はＤＰＦ２１によって捕集されてＮＯｘ浄化
触媒２０に達しないので、ＮＯｘ浄化触媒２０の浄化性
能の低下が防止される。また、ＤＰＦ２１の上流側にバ
ーナー２２が配設されているので、ＤＰＦ２１に微粒子
が多く付着して目づまり状態になり、排気ガスが流通し
難くなったときに、バーナー２２により微粒子を燃焼さ
せて除去することができる。In addition, in the same figure, 21 is a DPF (diesel particulate filter) disposed in the exhaust pipe 18 upstream of the NOx purification catalyst 20 to collect and filter particulates in the exhaust gas, and 22 is a DPF 21 upstream of the DPF 21. This burner is disposed on the wall of the exhaust pipe 18 and burns particulates attached to the DPF 21. In this way, the NOx purification catalyst 20
Since the DPF 21 is disposed upstream of the exhaust gas, fine particles in the exhaust gas are collected by the DPF 21 and do not reach the NOx purification catalyst 20, thereby preventing a reduction in the purification performance of the NOx purification catalyst 20. In addition, since the burner 22 is disposed upstream of the DPF 21, when the DPF 21 is clogged with a large number of particles and it becomes difficult for exhaust gas to flow through, the burner 22 burns the particles. Can be removed.
また、第１図及び第２図において、２４はＤＰＦ２１の
上流側つまりＮＯＸ浄化触媒２０の上流側の排気管１８
及びＮＯｘ浄化触媒２０の下流側の排気管１８と、吸気
管１２とを各々連通させ、排気ガスを排気管１８から吸
気管１２に還流させるＥＧＲ通路、２６Ａ、２６ＢはＥ
ＧＲ通路２４における排気管１８との連通部近傍に介設
され、ＮＯｘ浄化触媒２０の上流側からの還流量、及び
ＮＯＸ浄化触媒２０の下流側からの還流量を各々可変す
るＥＧＲバルブ、２８Ａ、２８Ｂはオルタネータに装着
された真空ポンプ２９とＥＧＲパルプ２６Ａ ２６Ｂ
とを連通させ、ＥＧＲバルブ２６Ａ、２６Ｂに負圧を導
入する負圧導入通路、３０Ａ、３０Ｂは負圧導入通路２
８Ａ、２８Ｂに介設され、ＥＧＲバルブ２６Ａ、２６Ｂ
の開度をデユーティ制御により調節するＥＧＲ用ソリソ
レノイドバルブる。In FIGS. 1 and 2, 24 is an exhaust pipe 18 upstream of the DPF 21, that is, upstream of the NOx purification catalyst 20.
EGR passages 26A and 26B communicate the exhaust pipe 18 on the downstream side of the NOx purification catalyst 20 with the intake pipe 12 and recirculate the exhaust gas from the exhaust pipe 18 to the intake pipe 12.
an EGR valve, 28A, which is interposed near the communication portion with the exhaust pipe 18 in the GR passage 24 and varies the amount of recirculation from the upstream side of the NOx purification catalyst 20 and the amount of recirculation from the downstream side of the NOx purification catalyst 20; 28B is the vacuum pump 29 attached to the alternator and EGR pulp 26A 26B
Negative pressure introduction passages 30A and 30B communicate with each other and introduce negative pressure into the EGR valves 26A and 26B, and 30A and 30B are negative pressure introduction passages 2.
8A, 28B, EGR valves 26A, 26B
EGR solenoid valve whose opening degree is adjusted by duty control.
以上説明したＥＧＲ通路２４、ＥＧＲバルブ２６Ａ、２
６Ｂ、負圧導入通路２８Ａ、２８Ｂ、真空ポンプ２９及
びＥＧＲ用ソリソレノイドバルブ３０Ａ０ＢによってＥ
ＧＲ装置３２が構成されており、このＥＧＲ装置３２に
よって、排気ガスが吸気系に還流され、燃焼室の熱容量
が高められる結果、排気ガス中へのＮＯｘ排出量が低減
する。The EGR passage 24 and EGR valves 26A and 2 explained above
6B, negative pressure introduction passages 28A, 28B, vacuum pump 29, and EGR solenoid valve 30A0B.
A GR device 32 is configured, and as a result of this EGR device 32, exhaust gas is recirculated to the intake system and the heat capacity of the combustion chamber is increased, the amount of NOx discharged into the exhaust gas is reduced.
なお、本実施例では、吸気管１２におけるＥＧＲ通路２
４との連通部より上流側に吸気絞り弁１２ａが配設され
ている。その理由は、ディーゼルエンジンでは、吸気圧
と排気圧との差が小さいため、排気ガスがＥＧＲ通路２
４から吸気管１２へ流入しにくい。そこで、排気ガスを
還流させる際、この吸気絞り弁１２ａを絞って所定の吸
気圧にし、排気ガスを還流させ易くするためである。も
っとも、この場合でも、排気ガスの還流量はＥＧＲバル
ブ２６Ａ、２６Ｂの開度を調節することによって調整す
る。Note that in this embodiment, the EGR passage 2 in the intake pipe 12
An intake throttle valve 12a is disposed on the upstream side of the communication portion with 4. The reason for this is that in a diesel engine, the difference between intake pressure and exhaust pressure is small, so exhaust gas flows into the EGR passage 2.
4 into the intake pipe 12. Therefore, when the exhaust gas is recirculated, the intake throttle valve 12a is throttled to a predetermined intake pressure to facilitate the recirculation of the exhaust gas. However, even in this case, the amount of recirculation of exhaust gas is adjusted by adjusting the opening degrees of the EGR valves 26A and 26B.
また、第１図において、３６は二次エアの供給源である
エアポンプ、３８はエアポンプ３６と、排気管１８にお
けるＤＰＦ２１とＮＯＸ浄化触媒２０との間とを連通さ
せ、二次エアを排気管１８へ供給するための二次エア通
路、４０は二次エア通路３６を流通する二次エア量を可
変する二次工ア調整バルブ、４２は前記真空ポンプ２９
と二次エア！［バルブ４０とを連通させ、二次エア調整
バルブ４０に負圧を導入する負圧導入通路、４４は負圧
導入通路４２に介設され、二次エア調整バルブ４０の開
度をデユーティ制御により調節する二次エア用ソレノイ
ドバルブである。Further, in FIG. 1, reference numeral 36 is an air pump that is a supply source of secondary air, and 38 is a communication between the air pump 36 and the DPF 21 and the NOx purification catalyst 20 in the exhaust pipe 18, and the secondary air is supplied to the exhaust pipe 18. 40 is a secondary air adjustment valve that changes the amount of secondary air flowing through the secondary air passage 36; 42 is the vacuum pump 29;
And secondary air! [A negative pressure introduction passage 44 is interposed in the negative pressure introduction passage 42 to communicate with the valve 40 and introduce negative pressure into the secondary air adjustment valve 40, and the opening degree of the secondary air adjustment valve 40 is controlled by duty control. This is a solenoid valve for regulating secondary air.
以上説明した二次エアポンプ３６、二次エア通路３８、
二次エア調整バルブ４０、負圧導入通路４２及び二次エ
ア用ソレノイドバルブ４４によって、ＮＯｘ浄化触媒２
０の上流に二次エアを供給する二次エア供給装置４６が
構成されており、排気ガスの空燃比がリッチで且つ排気
ガスの温度が高いときに、この二次エア供給装置４６に
よって排気ガス中に二次エアを供給すると、ＮＯｘ浄化
触媒２０に流入する排気ガスがリーン傾向になると共に
排気ガス温度が低下して、ＮＯｘ浄化触媒２０の保護が
図られると共にＮＯＸ浄化触媒の性能が向上する。The secondary air pump 36, the secondary air passage 38, described above,
The secondary air adjustment valve 40, negative pressure introduction passage 42, and secondary air solenoid valve 44 control the
A secondary air supply device 46 is configured to supply secondary air upstream of the exhaust gas.When the air-fuel ratio of exhaust gas is rich and the temperature of the exhaust gas is high, this secondary air supply device 46 When secondary air is supplied into the NOx purification catalyst 20, the exhaust gas flowing into the NOx purification catalyst 20 tends to be lean and the exhaust gas temperature decreases, thereby protecting the NOx purification catalyst 20 and improving the performance of the NOx purification catalyst. .
また、第１図において、５０はエンジン冷却水温度を検
出する冷却水温度センサ、５１はエンジンの吸気温度を
検出する吸気温度センサ、５２はエンジンの吸気圧を検
出する吸気圧センサ、５４はＮＯｘ浄化触媒２０の上流
側の排気ガス温度を検出する排気ガス温度センサ、５５
は排気ガス中の酸素濃度を検出する０２センサ、５６は
排気ガスの圧力を検出する圧力センサであって、この圧
力センサ５６によりＤＰＦ２１のフィルターに微粒子が
多く付着してフィルターが目づまりを起こしている状態
を検知できる。Further, in FIG. 1, 50 is a cooling water temperature sensor that detects the engine cooling water temperature, 51 is an intake air temperature sensor that detects the engine intake air temperature, 52 is an intake pressure sensor that detects the engine intake pressure, and 54 is NOx an exhaust gas temperature sensor 55 that detects the exhaust gas temperature upstream of the purification catalyst 20;
02 sensor detects the oxygen concentration in exhaust gas, 56 is a pressure sensor that detects the pressure of exhaust gas, and this pressure sensor 56 causes a lot of particles to adhere to the filter of the DPF 21, causing the filter to become clogged. The state can be detected.
また、第１図において、６０はエンジンの低負荷時には
排気ガスをＮＯｘ浄化触媒２０の上流側から還流させる
一方、エンジンの高負荷時には排気ガスをＮＯｘ浄化触
媒２０の下流側から還流させるようＥＧＲ装置３２を制
御するＥＧＲ制御手段としてのＣＰＵ内蔵のコントロー
ルユニットである。In FIG. 1, reference numeral 60 denotes an EGR device that recirculates exhaust gas from the upstream side of the NOx purification catalyst 20 when the engine is under low load, while recirculating exhaust gas from the downstream side of the NOx purification catalyst 20 when the engine is under high load. This is a control unit with a built-in CPU as an EGR control means for controlling 32.
そして、コントロールユニット６０は、冷却水温度セン
サ５０からエンジン冷却水温度信号、吸気温度センサ５
１からエンジンの吸気温度信号、吸気圧センサ５２から
のエンジンの吸気圧信号、排気ガス温度センサ５４から
排気ガス温度信号、０２センサ５５からの排気ガスの空
燃比信号、圧力センサ５６からの排気ガス圧力信号、燃
料噴射ポンプ１５からのエンジン回転数信号及びエンジ
ン負荷信号等を受け、排気ガス温度信号及び空燃比信号
に基づき二次エア用ソレノイドバルブ４４をデユーティ
制御し、圧力センサ５６からの排気ガス圧力信号に基づ
きバーナー２２の燃焼を制御する。The control unit 60 receives an engine coolant temperature signal from the coolant temperature sensor 50, and receives an engine coolant temperature signal from the coolant temperature sensor 50.
1 to the engine intake temperature signal, the engine intake pressure signal from the intake pressure sensor 52, the exhaust gas temperature signal from the exhaust gas temperature sensor 54, the exhaust gas air-fuel ratio signal from the 02 sensor 55, and the exhaust gas from the pressure sensor 56. In response to the pressure signal, the engine speed signal and the engine load signal from the fuel injection pump 15, the secondary air solenoid valve 44 is duty-controlled based on the exhaust gas temperature signal and the air-fuel ratio signal, and the exhaust gas from the pressure sensor 56 is controlled. Combustion of the burner 22 is controlled based on the pressure signal.
また、コントロールユニット６０は、エンジン負荷信号
及びエンジン回転数信号に基づき、第３図に示すように
、エンジンの高負荷時（同図において（ａ）で示す）に
はＮＯｘ浄化触媒２０の下流側から排気ガスを還流させ
、エンジンの低負荷時（同図において（ｂ）で示す）に
はＮＯｘ浄化触媒の上流側から排気ガスを還流させ、エ
ンジンの中負荷時（同図において（Ｃ）で示す）には排
気ガスをいずれからも還流させないか若しくは下流側か
ら少量還流させるようにＥＧＲ用ソリソレノイドバルブ
３０Ａ０Ｂを各々制御する。なお、前記実施例に代えて
、エンジン負荷信号のみに基づいて前記のような制御を
行なってもよい。Further, the control unit 60 controls the downstream side of the NOx purification catalyst 20 when the engine is under high load (indicated by (a) in the figure), as shown in FIG. 3, based on the engine load signal and the engine rotation speed signal. The exhaust gas is recirculated from the upstream side of the NOx purification catalyst when the engine is under low load (indicated by (b) in the same figure), and the exhaust gas is recirculated from the upstream side of the NOx purification catalyst when the engine is under medium load (indicated by (C) in the same figure). (shown), the EGR soli solenoid valves 30A0B are controlled so that the exhaust gas is not recirculated from either side or is recirculated in a small amount from the downstream side. Note that instead of the above embodiment, the above control may be performed based only on the engine load signal.
以上のように、エンジンの低負荷時及び高負荷時、つま
りＮＯｘ浄化触媒の浄化性能が低い場合にＥＧＲ装置３
２によって、燃焼室の熱容量が高められるため排気ガス
中へのＮＯｘの排出量が低減すると共に、排気ガス中の
Ｎｏの分圧が高まってＮＯｘ浄化率の向上が図られる。As described above, the EGR device 3
2, the heat capacity of the combustion chamber is increased, so the amount of NOx discharged into the exhaust gas is reduced, and the partial pressure of No in the exhaust gas is increased to improve the NOx purification rate.
また、エンジンの低負荷時には排気ガスをＮ。Also, when the engine is under low load, the exhaust gas is reduced to N.
×浄化触媒２０の上流側から取出すので高温の排気ガス
が得られ、この高温の排気ガスが吸気系に還流するため
エンジン燃焼性の向上が図られる。*Since the exhaust gas is taken out from the upstream side of the purification catalyst 20, high-temperature exhaust gas is obtained, and since this high-temperature exhaust gas is recirculated to the intake system, engine combustibility is improved.
さらに、エンジンの高負荷時には排気ガスをＮＯｘ浄化
触媒２０の下流側から取出すため、Ｎ。Furthermore, when the engine is under high load, the exhaust gas is taken out from the downstream side of the NOx purification catalyst 20, so N gas is used.
×がＯ！とＮ２とに分解されて比熱の高い（つまり分子
数が多い）排気ガスが吸気系に還流される結果、燃焼室
の熱容量が高められると共に、ＮＯｘ浄化触媒２０を通
過することにより低温になった排気ガスが還流するので
、ＮＯｘの排出が低減する。× is O! As a result of decomposing the exhaust gas into N2 and N2 and having a high specific heat (that is, a large number of molecules), the exhaust gas is returned to the intake system, increasing the heat capacity of the combustion chamber and reducing the temperature by passing through the NOx purification catalyst 20. Since the exhaust gas is recirculated, NOx emissions are reduced.
なお、ＥＧＲ装置３２による排気ガスの還流量について
は、第４図に示すような、平均有効圧（エンジンの負荷
に相当する）とエンジンの回転数とに応じて設定される
ＥＧＲ率マツプに基づくことが好ましい。Note that the amount of recirculation of exhaust gas by the EGR device 32 is based on an EGR rate map that is set according to the average effective pressure (corresponding to the engine load) and the engine speed, as shown in FIG. It is preferable.
第５図及び第６図は本発明の第２実施例に係るエンジン
の排気ガス浄化装置がガソリンエンジン１０Ｂに適用さ
れた場合を示し、前記第１実施例と同様、吸気管１２、
インテークマニホールド１４、エキゾーストマニホール
ド１６、排気管１８、ＮＯｘ浄化触媒２０が配設されて
いる。5 and 6 show a case where the engine exhaust gas purification device according to the second embodiment of the present invention is applied to a gasoline engine 10B, in which, as in the first embodiment, the intake pipe 12,
An intake manifold 14, an exhaust manifold 16, an exhaust pipe 18, and a NOx purification catalyst 20 are provided.
また、本第２実施例はガソリンエンジンＩＯＢに適用し
た場合であるから、排気ガス中の微粒子は問題にならな
いためＤＰＦ２１及びバーナー２２が配設されておらず
、代わりに、排気ガス中のＩＣ及びＣ○を酸化させる酸
化触媒２３が配設されている。従って、本第２実施例に
おいては、ＥＧＲ通路２４は、酸化触媒２３の上流側の
排気管１８及びＮＯｘ浄化触媒２０の下流側の排気管１
８と、吸気管１２とを各々連通させている。In addition, since this second embodiment is applied to a gasoline engine IOB, fine particles in the exhaust gas are not a problem, so the DPF 21 and the burner 22 are not provided, and instead, the IC and burner 22 in the exhaust gas are not provided. An oxidation catalyst 23 for oxidizing C○ is provided. Therefore, in the second embodiment, the EGR passage 24 includes the exhaust pipe 18 upstream of the oxidation catalyst 23 and the exhaust pipe 18 downstream of the NOx purification catalyst 20.
8 and the intake pipe 12, respectively.
また、本第２実施例では、ＥＧＲ装置３２の負圧導入通
路２８Ａ、２８Ｂ及び二次エア供給装置４６の負圧導入
通路４２は各々吸気絞り弁１２ａの下流側の吸気管１２
に連通しており、前記真空ポンプ２つに代えて吸気管１
２から負圧を導入している。Further, in the second embodiment, the negative pressure introduction passages 28A, 28B of the EGR device 32 and the negative pressure introduction passage 42 of the secondary air supply device 46 are connected to the intake pipe 12 downstream of the intake throttle valve 12a.
The intake pipe 1 is connected to the vacuum pump in place of the two vacuum pumps.
Negative pressure is introduced from 2.
さらに、本第２実施例では、コントロールユニット６０
は、エンジン回転数センサ５７からエンジン回転数信号
、エンジン吸入負圧センサ５８からエンジン負荷信号等
を受けて、前記同様つまりエンジンの低負荷時には排気
ガスをＮＯｘ浄化触媒２０の上流側から還流させる一方
、エンジンの高負荷時には排気ガスをＮＯｘ浄化触媒２
ｏの下流側から還流させるようにＥＧＲ用ソレノイドバ
ルブ３０Ａ、３０Ｂを各々制御する。Furthermore, in the second embodiment, the control unit 60
receives an engine speed signal from the engine speed sensor 57 and an engine load signal from the engine suction negative pressure sensor 58, and as described above, when the engine load is low, the exhaust gas is recirculated from the upstream side of the NOx purification catalyst 20. When the engine is under high load, the exhaust gas is converted to NOx purification catalyst 2.
The EGR solenoid valves 30A and 30B are controlled so that the EGR solenoid valves 30A and 30B are recirculated from the downstream side of the EGR.
なお、本第２実施例に係るエンジンの排気ガス浄化装置
がガソリンエンジンＩＯＢに適用される場合、排気ガス
の還流量については、第７図に示すような、平均有効圧
とエンジンの回転数とに応じて設定されるＥＧＲ率マツ
プに基づくことが好ましい。Note that when the engine exhaust gas purification device according to the second embodiment is applied to a gasoline engine IOB, the amount of recirculation of exhaust gas is determined based on the average effective pressure and engine rotation speed as shown in FIG. It is preferable to use an EGR rate map set according to the EGR rate map.
（発明の効果）
以上説明したように、本発明に係るエンジンの排気ガス
浄化装置によると、排気ガスをエンジンの低負荷時には
ＮＯｘ浄化触媒の上流側から還流させると共に、高負荷
時にはＮＯｘ浄化触媒の下流側から還流させるようにし
たため、ＮＯｘ浄化触媒の浄化性能が低いエンジンの低
負荷時及び高負荷時には、ＥＧＲ装置により排気ガス中
に排出されるＮ０ｘｊｌを低減させてＮＯｘ浄化触媒の
浄化性能を補う二とができる。(Effects of the Invention) As explained above, according to the engine exhaust gas purification device according to the present invention, the exhaust gas is recirculated from the upstream side of the NOx purification catalyst when the engine is under low load, and the exhaust gas is recirculated from the upstream side of the NOx purification catalyst when the engine is under high load. Since the flow is recirculated from the downstream side, when the engine is under low load or under high load, when the NOx purification catalyst has low purification performance, the EGR device reduces the NOxjl emitted into the exhaust gas and compensates for the purification performance of the NOx purification catalyst. I can do two things.
また、エンジンの低負荷時にはＮＯｘ浄化触媒の上流側
から取出した高温状態の排気ガスを還流させるので、エ
ンジンの燃焼性の向上を図ることができると共に、エン
ジンの高負荷時にはＮＯｘ浄化触媒の下流側から取出し
た熱容量が高く且つ低温状態の排気ガスを還流させるの
で、ＮＯＸ排出量の低減を図ることができる。In addition, when the engine is under low load, the high-temperature exhaust gas taken out from the upstream side of the NOx purification catalyst is recirculated, making it possible to improve engine combustibility. Since the exhaust gas extracted from the exhaust gas having a high heat capacity and at a low temperature is recirculated, it is possible to reduce the amount of NOx emissions.
第１図〜第４図は本発明の第１実施例を示し、第１図は
エンジンの排気ガス浄化装置の全体構成図、第２図はＥ
ＧＲ装置の断面図、第３図はＥＧＲ装置に対する制御概
念図、第４図はエンジン回転数と平均有効圧に対応する
ＥＧＲ率マツプ図、′ｍ５図〜第７図は本発明の第２実
施例を示し、第５図はエンジンの排気ガス浄化装置の全
体構成図、第６図はＥＧＲ装置の断面図、第７図はエン
ジン回転数と平均有効圧に対応するＥＧＲ率マツプ図、
第８図はＮＯｘ浄化触媒における排気ガス温度とＮＯＸ
浄化性能との関係を示す図である。
１０Ａ・・・ディーゼルエンジン
１０Ｂ・・・ガソリンエンジン
１２・・・吸気管
１８・・・排気管
２０・・・ＮＯｘ浄化触媒
２１・・・ＤＰＦ
２３・・・酸化触媒
２４・・・ＥＧＲ通路
２６Ａ、２６Ｂ・・・ＥＧＲバルブ
２８Ａ、２８Ｂ・・・負圧導入通路
２９・・・真空ポンプ
３０Ａ、３０Ｂ
・・・ＥＧＲ用ソリソレノイドパ
ルプ・・・ＥＧＲ装置
６０・・・コントロールユニット
工゛／ジ゛゛７回転数
第３図1 to 4 show a first embodiment of the present invention, FIG. 1 is an overall configuration diagram of an engine exhaust gas purification device, and FIG. 2 is an E
A sectional view of the GR device, FIG. 3 is a conceptual diagram of control for the EGR device, FIG. 4 is an EGR rate map diagram corresponding to engine speed and average effective pressure, and FIGS. For example, Fig. 5 is an overall configuration diagram of an engine exhaust gas purification device, Fig. 6 is a sectional view of an EGR device, Fig. 7 is an EGR rate map diagram corresponding to engine speed and average effective pressure,
Figure 8 shows the exhaust gas temperature and NOx at the NOx purification catalyst.
It is a figure showing the relationship with purification performance. 10A...Diesel engine 10B...Gasoline engine 12...Intake pipe 18...Exhaust pipe 20...NOx purification catalyst 21...DPF 23...Oxidation catalyst 24...EGR passage 26A, 26B...EGR valve 28A, 28B...Negative pressure introduction passage 29...Vacuum pump 30A, 30B...Soli solenoid pulp for EGR...EGR device 60...Control unit engineering/division 7 Rotation speed figure 3
Claims (1)
触媒を備えたエンジンの排気ガス浄化装置において、 前記ＮＯ＿ｘ浄化触媒の上流側及び下流側から排気ガス
を取出して吸気系へ還流させると共に、前記ＮＯ＿ｘ浄
化触媒の上流側からの還流と下流側からの還流とを切換
えるＥＧＲ装置と、 エンジンの低負荷時には排気ガスを前記ＮＯ＿ｘ浄化触
媒の上流側から還流させる一方、エンジンの高負荷時に
は排気ガスを前記ＮＯ＿ｘ浄化触媒の下流側から還流さ
せるよう前記ＥＧＲ装置を制御するＥＧＲ制御手段とを
備えたことを特徴とするエンジンの排気ガス浄化装置。(1) In an engine exhaust gas purification device including an NO_x purification catalyst containing Cu in the engine exhaust system, exhaust gas is extracted from the upstream and downstream sides of the NO_x purification catalyst and recirculated to the intake system; The EGR device switches between recirculation from the upstream side of the NO_x purification catalyst and recirculation from the downstream side. An exhaust gas purification device for an engine, comprising: EGR control means for controlling the EGR device to cause recirculation from the downstream side of the NO_x purification catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1209146A JP2675405B2 (en) | 1989-08-12 | 1989-08-12 | Engine exhaust gas purification device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1209146A JP2675405B2 (en) | 1989-08-12 | 1989-08-12 | Engine exhaust gas purification device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0374561A true JPH0374561A (en) | 1991-03-29 |
| JP2675405B2 JP2675405B2 (en) | 1997-11-12 |
Family
ID=16568073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1209146A Expired - Lifetime JP2675405B2 (en) | 1989-08-12 | 1989-08-12 | Engine exhaust gas purification device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2675405B2 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0693839A (en) * | 1992-09-10 | 1994-04-05 | Hitachi Ltd | Exhaust emission control device for internal combustion engine |
| JPH09122447A (en) * | 1995-10-27 | 1997-05-13 | Sangyo Souzou Kenkyusho | Purifying process for engine exhaust gas |
| WO2004018850A1 (en) * | 2002-08-26 | 2004-03-04 | Hitachi, Ltd. | Apparatus and method for clarifying exhaust gas of diesel engine |
| FR2872861A1 (en) * | 2004-07-06 | 2006-01-13 | Peugeot Citroen Automobiles Sa | Exhaust gas re-circulating system for internal combustion engine, has control unit to control relative proportion of processed and unprocessed exhaust gas that are re-circulated through conduits towards combustion chamber |
| JP2008248878A (en) * | 2007-03-02 | 2008-10-16 | Honda Motor Co Ltd | Internal combustion engine and control device for internal combustion engine |
| WO2011128943A1 (en) * | 2010-04-15 | 2011-10-20 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine |
| US8813490B2 (en) | 2009-02-06 | 2014-08-26 | Honda Motor Co., Ltd. | Internal combustion engine exhaust emission control device and exhaust emission control method |
Families Citing this family (3)
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|---|---|---|---|---|
| JP2006022770A (en) | 2004-07-09 | 2006-01-26 | Toyota Motor Corp | Exhaust emission control device for internal combustion engine |
| JP5053306B2 (en) | 2009-02-06 | 2012-10-17 | 本田技研工業株式会社 | Exhaust gas purification device for internal combustion engine |
| JP5365261B2 (en) * | 2009-03-02 | 2013-12-11 | マツダ株式会社 | Method and system for controlling exhaust gas recirculation in an internal combustion engine |
-
1989
- 1989-08-12 JP JP1209146A patent/JP2675405B2/en not_active Expired - Lifetime
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0693839A (en) * | 1992-09-10 | 1994-04-05 | Hitachi Ltd | Exhaust emission control device for internal combustion engine |
| JPH09122447A (en) * | 1995-10-27 | 1997-05-13 | Sangyo Souzou Kenkyusho | Purifying process for engine exhaust gas |
| WO2004018850A1 (en) * | 2002-08-26 | 2004-03-04 | Hitachi, Ltd. | Apparatus and method for clarifying exhaust gas of diesel engine |
| FR2872861A1 (en) * | 2004-07-06 | 2006-01-13 | Peugeot Citroen Automobiles Sa | Exhaust gas re-circulating system for internal combustion engine, has control unit to control relative proportion of processed and unprocessed exhaust gas that are re-circulated through conduits towards combustion chamber |
| JP2008248878A (en) * | 2007-03-02 | 2008-10-16 | Honda Motor Co Ltd | Internal combustion engine and control device for internal combustion engine |
| US8205449B2 (en) | 2007-03-02 | 2012-06-26 | Honda Motor Co., Ltd. | Internal combustion engine and control system for internal combustion engine |
| US8813490B2 (en) | 2009-02-06 | 2014-08-26 | Honda Motor Co., Ltd. | Internal combustion engine exhaust emission control device and exhaust emission control method |
| WO2011128943A1 (en) * | 2010-04-15 | 2011-10-20 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine |
| CN102822463A (en) * | 2010-04-15 | 2012-12-12 | 丰田自动车株式会社 | Exhaust gas purification device for internal combustion engine |
| JP5141824B2 (en) * | 2010-04-15 | 2013-02-13 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2675405B2 (en) | 1997-11-12 |
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