JPH0586847A - Exhaust emission control device for engine having mechanical supercharger - Google Patents
Exhaust emission control device for engine having mechanical superchargerInfo
- Publication number
- JPH0586847A JPH0586847A JP3247956A JP24795691A JPH0586847A JP H0586847 A JPH0586847 A JP H0586847A JP 3247956 A JP3247956 A JP 3247956A JP 24795691 A JP24795691 A JP 24795691A JP H0586847 A JPH0586847 A JP H0586847A
- Authority
- JP
- Japan
- Prior art keywords
- passage
- exhaust
- air
- exhaust gas
- fuel ratio
- 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.)
- Pending
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/02—EGR systems specially adapted for supercharged engines
- F02M26/03—EGR systems specially adapted for supercharged engines with a single mechanically or electrically driven intake charge compressor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
- F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
- F02M26/42—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories having two or more EGR passages; EGR systems specially adapted for engines having two or more cylinders
-
- 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
- F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
- F02B29/04—Cooling of air intake supply
- F02B29/0406—Layout of the intake air cooling or coolant circuit
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Exhaust-Gas Circulating Devices (AREA)
- Exhaust Gas After Treatment (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、吸気通路に機械式過給
機を備えるとともにこの過給機の下流の吸気通路に排気
ガスが還流されるようになっている機械式過給機付エン
ジンにおける排気ガス浄化装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine with a mechanical supercharger in which an intake passage is provided with a mechanical supercharger and exhaust gas is recirculated to an intake passage downstream of the supercharger. The present invention relates to an exhaust gas purification device in.
【0002】[0002]
【従来の技術】従来から、エンジンの排気通路と吸気通
路との間に排気ガス還流通路(EGR通路)を接続し、
この通路に排気ガス還流量を制御する制御弁(EGR
弁)を設けた排気ガス還流装置は一般に知られている。2. Description of the Related Art Conventionally, an exhaust gas recirculation passage (EGR passage) is connected between an exhaust passage and an intake passage of an engine,
A control valve (EGR
Exhaust gas recirculation devices provided with valves are generally known.
【0003】また、例えば実開昭61−47479号公
報に示されるように、吸気通路に機械式過給機を備えた
エンジンにおいて、排気通路と機械式過給機下流の吸気
通路との間に排気ガス還流通路を接続するとともに、高
過給運転時に、排気ガス還流通路の制御弁を強制的に開
くことにより、この通路を過給機に対するバイパス通路
として利用し、過給エアを排気ガス還流通路を通して排
気通路にバイパスするようにしたものがある。In an engine having a mechanical supercharger in the intake passage, for example, as disclosed in Japanese Utility Model Laid-Open No. 61-47479, between the exhaust passage and the intake passage downstream of the mechanical supercharger. By connecting the exhaust gas recirculation passage and forcibly opening the control valve of the exhaust gas recirculation passage during high supercharging operation, this passage is used as a bypass passage for the supercharger and the supercharged air is recirculated to the exhaust gas. There is one that bypasses the exhaust passage through the passage.
【0004】[0004]
【発明が解決しようとする課題】ところで、排気通路の
触媒より上流に二次エアを供給し、排気浄化作用を高め
るようにした技術は知られている(例えば特開平1−2
37320号公報参照)。By the way, a technique is known in which secondary air is supplied upstream of the catalyst in the exhaust passage to enhance the exhaust gas purification action (for example, JP-A 1-2).
See Japanese Patent No. 37320).
【0005】そこで、上記実開昭61−47479号公
報に示された装置において、高過給時に排気ガス還流通
路を通して排気通路にバイパスされるエアを二次エアと
して利用することが考えられる。Therefore, in the apparatus disclosed in Japanese Utility Model Laid-Open No. 61-47479, it is conceivable to use the air bypassed to the exhaust passage through the exhaust gas recirculation passage as the secondary air at the time of high supercharging.
【0006】しかし、この場合の排気ガス還流性能、二
次エアとして利用するときの浄化性能、高負荷領域での
出力性能および耐ノック性等を良好にするためには、改
善の余地があった。However, there is room for improvement in order to improve the exhaust gas recirculation performance in this case, the purification performance when used as secondary air, the output performance in the high load region, and the knock resistance. ..
【0007】本発明は上記の事情に鑑み、排気ガス還流
通路を二次エア通路に兼用し、それぞれの機能を良好に
発揮させて排気ガス浄化性能を高めるとともに、高負荷
時の出力性能および耐ノックを向上し、かつ、排気温度
の上昇を抑制することができる機械式過給機付エンジン
の排気ガス浄化装置を提供することを目的とする。In view of the above circumstances, the present invention uses the exhaust gas recirculation passage also as a secondary air passage to enhance the exhaust gas purifying performance by exerting its respective functions satisfactorily, and at the same time, to improve the output performance under high load and durability. An object of the present invention is to provide an exhaust gas purifying apparatus for an engine with a mechanical supercharger that can improve knocking and suppress an increase in exhaust temperature.
【0008】[0008]
【課題を解決するための手段】上記目的を達成するため
に、本発明は、エンジンの吸気通路に機械式過給機を設
け、排気通路と吸気通路との間に排気ガス還流通路を接
続し、この通路中に制御弁を設けた機械式過給機付エン
ジンにおいて、排気浄化用の触媒より上流の排気通路と
機械式過給機より下流の吸気通路との間に排気ガス還流
通路を接続して、この排気ガス還流通路に作用する吸気
圧力が排気圧力よりも高くなる過給領域では排気ガス還
流通路を通して吸気通路から排気通路へ二次エアが導か
れるように構成する一方、低負荷から過給領域における
全負荷より所定量低い設定負荷までにわたる運転領域
で、上記排気ガス還流通路の制御弁を開弁させる制御弁
コントロール手段と、上記吸気圧力が排気圧力よりも低
い運転領域では燃焼室内の混合気の空燃比を略理論空燃
比とし、上記吸気圧力が排気圧力よりも高くなる領域で
は上記空燃比をリッチにする空燃比コントロール手段と
を備えたものである。To achieve the above object, the present invention provides a mechanical supercharger in an intake passage of an engine, and connects an exhaust gas recirculation passage between the exhaust passage and the intake passage. , In an engine with a mechanical supercharger having a control valve in this passage, connect an exhaust gas recirculation passage between the exhaust passage upstream of the catalyst for exhaust purification and the intake passage downstream of the mechanical supercharger Then, in the supercharging region where the intake pressure acting on the exhaust gas recirculation passage is higher than the exhaust pressure, the secondary air is guided from the intake passage to the exhaust passage through the exhaust gas recirculation passage, while the low load is applied. Control valve control means for opening the control valve of the exhaust gas recirculation passage, and combustion in the operating region in which the intake pressure is lower than the exhaust pressure, in the operating region over a set load lower than the full load in the supercharging region by a predetermined amount. The air-fuel ratio of the mixture of the inner and the stoichiometric air-fuel ratio, in a region where the intake pressure is higher than the exhaust pressure is obtained and a air-fuel ratio control means for the air-fuel ratio rich.
【0009】この構成において、上記触媒を三元触媒と
するとともに、排気通路の排気ガス還流通路接続部より
上流に、NOx用補助触媒を配置してもよい。In this structure, the catalyst may be a three-way catalyst, and the NOx auxiliary catalyst may be arranged upstream of the exhaust gas recirculation passage connecting portion of the exhaust passage.
【0010】また、排気通路の排気ガス還流通路よりも
下流にO2 センサを具備する一方、上記空燃比コントロ
ール手段は、排気ガス還流通路の制御弁が開弁される運
転領域で上記O2 センサにより検出される見掛け上の空
燃比を略理論空燃比とするようにフィードバック制御す
るように構成することが好ましい。Further, while an O 2 sensor is provided in the exhaust passage downstream of the exhaust gas recirculation passage, the air-fuel ratio control means has the O 2 sensor in an operating region where the control valve of the exhaust gas recirculation passage is opened. It is preferable to perform feedback control so that the apparent air-fuel ratio detected by the above is approximately the theoretical air-fuel ratio.
【0011】[0011]
【作用】上記構成によれば、過給機下流の吸気圧力が排
気圧力よりも低い低負荷側の運転領域では、排気ガス還
流通路を通して排気通路から吸気通路へ排気ガスの還流
が行われる。一方、上記設定負荷までの領域のうちで、
上記吸気圧力が排気圧力よりも高くなる領域では、排気
ガス還流通路を通して吸気通路から排気通路へ二次エア
が供給され、かつ、燃焼室内の混合気がリッチにされる
ことでNOxが低減される。また、高負荷域では排気ガ
ス還流および二次エア供給が停止され、過給による掃気
性が高められる。According to the above construction, exhaust gas is recirculated from the exhaust passage to the intake passage through the exhaust gas recirculation passage in the operating region on the low load side where the intake pressure downstream of the supercharger is lower than the exhaust pressure. On the other hand, in the area up to the above set load,
In the region where the intake pressure is higher than the exhaust pressure, secondary air is supplied from the intake passage to the exhaust passage through the exhaust gas recirculation passage, and the air-fuel mixture in the combustion chamber is made rich to reduce NOx. .. Further, in the high load region, the exhaust gas recirculation and the secondary air supply are stopped, and the scavenging property by supercharging is enhanced.
【0012】[0012]
【実施例】本発明の実施例を図面に基づいて説明する。
図1は本発明の一実施例による排気ガス還流装置を備え
たエンジン全体を示している。図示のエンジンはV形エ
ンジンであって、エンジン本体1は、シリンダブロック
2とその上方の一対のシリンダヘッド3と各シリンダヘ
ッド3上のヘッドカバー4等からなり、一対のバンク1
a,1bを有している。各バンク1a,1bには複数の
気筒が配設され、各気筒内のピストン5上方に燃焼室6
が形成されている。また、シリンダブロック2の下方部
にはクランク軸7が配置されている。Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an entire engine equipped with an exhaust gas recirculation system according to an embodiment of the present invention. The illustrated engine is a V-type engine, and an engine body 1 includes a cylinder block 2, a pair of cylinder heads 3 above the cylinder block 3, a head cover 4 on each cylinder head 3, and the like.
It has a and 1b. A plurality of cylinders are arranged in each bank 1a, 1b, and a combustion chamber 6 is provided above the piston 5 in each cylinder.
Are formed. A crankshaft 7 is arranged below the cylinder block 2.
【0013】上記燃焼室6には、吸気ポート9および排
気ポート10が開口し、吸気ポート9には吸気通路11
の下流側の各独立吸気通路11aが接続され、排気ポー
ト10には排気通路12の上流側のバンク別の排気マニ
ホールド13に設けられた独立吸気通路が接続されてい
る。上記吸気ポート9に対し、燃料を噴射供給するイン
ジェクタ14が具備されている。また、上記各吸気ポー
ト9および排気ポート10には吸気弁15および排気弁
16がそれぞれ具備されている。An intake port 9 and an exhaust port 10 are opened in the combustion chamber 6, and an intake passage 11 is provided in the intake port 9.
Each independent intake passage 11a on the downstream side is connected to the exhaust port 10, and an independent intake passage provided on the exhaust manifold 13 for each bank on the upstream side of the exhaust passage 12 is connected to the exhaust port 10. An injector 14 is provided to inject and supply fuel to the intake port 9. Further, the intake port 9 and the exhaust port 10 are provided with an intake valve 15 and an exhaust valve 16, respectively.
【0014】上記吸気通路11は上流部に共通吸気通路
11bを有し、この共通吸気通路11bには、上流側か
らエアクリーナ21、エアフローメータ22、スロット
ル弁23、過給機24およびインタークーラ25が配設
されており、インタークーラ25より下流側部分が2つ
の通路11cに分かれてバンク別のサージタンク26に
それぞれ接続され、バンク毎にこの各サージタンク26
に前記各独立吸気通路11aの上流端部が連結されてい
る。上記過給機24は、クランク軸7の回動力がベルト
27を介して伝達されることにより作動される機械式過
給機であり、特にリショルム型の内部圧縮型過給機が用
いられている。The intake passage 11 has a common intake passage 11b in the upstream portion, and an air cleaner 21, an air flow meter 22, a throttle valve 23, a supercharger 24 and an intercooler 25 are provided in the common intake passage 11b from the upstream side. A portion downstream of the intercooler 25 is divided into two passages 11c and connected to the surge tanks 26 for each bank. Each surge tank 26 is provided for each bank.
Is connected to the upstream end of each of the independent intake passages 11a. The supercharger 24 is a mechanical supercharger that is operated by the rotational power of the crankshaft 7 being transmitted through a belt 27, and in particular, a Risholum internal compression type supercharger is used. ..
【0015】上記インタークーラ25と各サージタンク
26との間の2つの通路11cは連通部28によって互
いに連通されている。過給機24より上流でスロットル
弁23の下流の吸気通路と上記連通部28との間には、
過給機24およびインタークーラ25をバイパスする過
給機バイパス通路29が設けられている。この過給機バ
イパス通路29には、ソレノイドバルブ30を介して導
かれる吸気圧力により作動されるアクチュエータ弁31
が設けられており、運転状態に応じてソレノイドバルブ
30が制御されることによりアクチュエータ弁31が開
閉される。例えば、低負荷時には過給機24の駆動が停
止されるとともにアクチュエータ弁31が開作動される
ことにより、吸気が過給機24をバイパスしてエンジン
本体1に供給されるようになっている。また、過給機2
4より下流でインタークーラ25より上流の吸気通路と
上記連通部28との間には、インタークーラ25をバイ
パスするインタークーラバイパス通路32が設けられ、
このインタークーラバイパス通路32中に、アクチュエ
ータ(図示せず)により運転状態に応じて開閉作動され
る開閉弁33が設けられている。そして、例えば過給に
よる吸気温度の上昇が比較的小さい中負荷程度までの運
転領域では、上記開閉弁33が開かれて、過給気がイン
タークーラバイパス通路32を通ってエンジン本体1に
供給されるようになっている。The two passages 11c between the intercooler 25 and each surge tank 26 are communicated with each other by a communication portion 28. Between the intake passage upstream of the supercharger 24 and downstream of the throttle valve 23 and the communication portion 28,
A supercharger bypass passage 29 that bypasses the supercharger 24 and the intercooler 25 is provided. In the supercharger bypass passage 29, an actuator valve 31 operated by the intake pressure introduced through a solenoid valve 30.
Is provided, and the actuator valve 31 is opened and closed by controlling the solenoid valve 30 according to the operating state. For example, when the load is low, the drive of the supercharger 24 is stopped and the actuator valve 31 is opened, so that the intake air bypasses the supercharger 24 and is supplied to the engine body 1. Also, the supercharger 2
4, an intercooler bypass passage 32 that bypasses the intercooler 25 is provided between the intake passage upstream of the intercooler 25 and upstream of the intercooler 25.
In the intercooler bypass passage 32, an opening / closing valve 33 that is opened / closed by an actuator (not shown) according to the operating state is provided. Then, for example, in an operating region up to a medium load where the rise in intake air temperature due to supercharging is relatively small, the opening / closing valve 33 is opened and supercharging air is supplied to the engine body 1 through the intercooler bypass passage 32. It has become so.
【0016】上記排気通路12と過給機24より下流の
吸気通路11との間には、EGR通路(排気ガス還流通
路)35が設けられている。このEGR通路35は、例
えば、排気通路側が2つに分岐して、両バンク1a,1
b毎の排気マニホールド13の集合部に接続される一
方、吸気通路側が、上記連通路28の両側の通路11c
付近に接続されている。このEGR通路35には、制御
信号に応じて作動するEGR弁(制御弁)36が設けら
れている。An EGR passage (exhaust gas recirculation passage) 35 is provided between the exhaust passage 12 and the intake passage 11 downstream of the supercharger 24. The EGR passage 35 is, for example, divided into two on the exhaust passage side so that both banks 1a, 1
While being connected to the collecting portion of the exhaust manifold 13 for each b, the intake passage side has passages 11c on both sides of the communication passage 28.
It is connected in the vicinity. The EGR passage 35 is provided with an EGR valve (control valve) 36 that operates in response to a control signal.
【0017】また、排気通路12には、空燃比検出用の
O2 センサ37、排気浄化用の触媒38およびサイレン
サ39が設けられている。上記O2 センサ37および触
媒38は、図1に示す例ではバンク別の排気通路にそれ
ぞれ設けられている。そして、EGR通路接続部より下
流にO2 センサ37が設けられ、さらにその下流に触媒
38が設けられている。Further, the exhaust passage 12 is provided with an O 2 sensor 37 for detecting an air-fuel ratio, a catalyst 38 for purifying exhaust gas, and a silencer 39. In the example shown in FIG. 1, the O 2 sensor 37 and the catalyst 38 are provided in the exhaust passage for each bank. An O 2 sensor 37 is provided downstream of the EGR passage connecting portion, and a catalyst 38 is provided further downstream thereof.
【0018】図2に示すように、EGR通路35の排気
通路側の、バンク別に分岐した通路35aは、さらに各
気筒別に分岐してその分岐部が各排気ポート付近に開口
している。上記EGR弁36はECU(コントロールユ
ニット)40により制御される。このECU40には、
エアフローメータ22およびO2 センサ37からの各信
号、エンジン回転数を検出する回転数センサ41からの
信号等が入力されている。またこのECU40から、上
記EGR弁36に制御信号が出力されるとともに、イン
ジェクタ14にも制御信号(噴射パルス)が出力されて
いる。As shown in FIG. 2, the passage 35a on the exhaust passage side of the EGR passage 35, which is branched for each bank, is further branched for each cylinder, and the branch portion opens to the vicinity of each exhaust port. The EGR valve 36 is controlled by an ECU (control unit) 40. In this ECU 40,
The signals from the air flow meter 22 and the O 2 sensor 37, the signal from the engine speed sensor 41 for detecting the engine speed, etc. are input. Further, the ECU 40 outputs a control signal to the EGR valve 36 and also outputs a control signal (injection pulse) to the injector 14.
【0019】上記ECU40は、図3に示すような制御
マップに基づいてEGR弁36およびインジェクタ14
の制御を行うようになっている。すなわち、この図にお
いて、LaはEGR弁36の開閉を切換えるための設定
負荷のラインであり、この設定負荷Laは、過給機下流
の吸気圧力が大気圧よりも高い過給領域内(図4中に一
点鎖線で示す0mmHgのラインよりも上)で、全負荷より
も所定量だけ低い負荷とされ、例えば、全負荷では吸気
圧力が700mmHgであるのに対して上記設定負荷Laは
400〜500mmHgの吸気圧力に相当する程度とされて
いる。そして、少なくとも低回転域(2500〜300
0rpm程度以下)における上記設定負荷Laより低負
荷側の運転領域A1,A2がEGR弁開領域とされてい
る。The ECU 40 controls the EGR valve 36 and the injector 14 based on the control map shown in FIG.
Is controlled. That is, in this figure, La is a set load line for switching the opening and closing of the EGR valve 36, and this set load La is in the supercharging region where the intake pressure downstream of the supercharger is higher than the atmospheric pressure (see FIG. 4). Above the line of 0 mmHg indicated by the alternate long and short dash line), the load is lower than the full load by a predetermined amount. For example, while the intake pressure is 700 mmHg at full load, the set load La is 400 to 500 mmHg. It is supposed to be equivalent to the intake pressure of. And at least the low rotation range (2500-300)
The operating regions A1 and A2 on the low load side of the set load La at about 0 rpm or less) are the EGR valve open region.
【0020】このEGR弁開領域のうちで、過給機24
より下流の吸気圧力が大気圧以下となる領域(上記吸気
圧力が排気圧力よりも低い運転領域)A1はEGR領域
となるもので、この領域A1では、EGRの量を適度に
調整するようにEGR弁36の開度が調整され、また、
上記吸気圧力が大気圧よりも高くなる過給領域(上記吸
気圧力が排気圧力よりも高くなる領域)A2は二次エア
供給領域となるもので、この領域では、吸気圧力の上昇
に応じて吸気通路側から排気通路側に流れる二次エア量
を適度に調整するようにEGR弁36の開度が制御され
る。例えば図4のように、過給圧と排気圧力との圧力差
(過給圧−排気圧力)が負のEGR領域では、その圧力
差が0に近づくにつれてEGR弁36の開度が大きくさ
れ、上記圧力差が0を超えて正になる二次エア領域で
は、圧力差が大きくなるにつれてEGR弁36の開度が
小さくされる。In this EGR valve open region, the supercharger 24
A region A1 in which the intake pressure is lower than the atmospheric pressure (an operating region in which the intake pressure is lower than the exhaust pressure) is an EGR region. In this region A1, the EGR amount is adjusted appropriately so as to adjust the EGR amount. The opening degree of the valve 36 is adjusted,
The supercharging region where the intake pressure is higher than the atmospheric pressure (the region where the intake pressure is higher than the exhaust pressure) A2 is a secondary air supply region. In this region, the intake air is increased in accordance with the increase of the intake pressure. The opening degree of the EGR valve 36 is controlled so that the amount of secondary air flowing from the passage side to the exhaust passage side is appropriately adjusted. For example, as shown in FIG. 4, in the EGR region where the pressure difference between the supercharging pressure and the exhaust pressure (supercharging pressure-exhaust pressure) is negative, the opening degree of the EGR valve 36 is increased as the pressure difference approaches 0. In the secondary air region where the pressure difference exceeds 0 and becomes positive, the opening degree of the EGR valve 36 is reduced as the pressure difference increases.
【0021】一方、空燃比の制御としては、上記EGR
弁開領域のうちのEGR領域A1では燃焼室内の混合気
の空燃比を略理論空燃比(λ=1)とし、二次エア供給
領域A2では上記空燃比をリッチに設定する。当実施例
では、02センサの上流に二次エアが供給されたときは
02 センサによる見掛け上の空燃比よりも燃焼室内の空
燃比がリッチになることに着目し、EGR領域A1およ
び二次エア供給領域A2のいずれにおいても02 センサ
による見掛け上の空燃比を略理論空燃比とするようにフ
ィードバック制御するようになっている。また、上記設
定負荷Laより高負荷側の領域では、フィードバック制
御が停止され、オープン制御により理論空燃比よりもリ
ッチな設定空燃比に制御されるようになっている。On the other hand, the air-fuel ratio is controlled by the above EGR.
In the EGR region A1 of the valve opening region, the air-fuel ratio of the air-fuel mixture in the combustion chamber is set to a substantially stoichiometric air-fuel ratio (λ = 1), and in the secondary air supply region A2, the air-fuel ratio is set rich. In this embodiment, when the secondary air is supplied upstream of the 0 2 sensor, the air-fuel ratio in the combustion chamber becomes richer than the apparent air-fuel ratio by the 0 2 sensor, and the EGR region A1 and the secondary air are In any of the supply regions A2, feedback control is performed so that the apparent air-fuel ratio by the 0 2 sensor is set to a substantially stoichiometric air-fuel ratio. Further, in the region on the higher load side than the set load La, the feedback control is stopped, and the open control is performed so that the set air-fuel ratio is richer than the theoretical air-fuel ratio.
【0022】上記の図3の制御領域のマップと図4のE
GR弁開度のマップは、予めECU40内に記憶されて
いる。そしてECU40は、エアフローメータ22およ
び回転数センサ41等からの信号に基づいて運転状態を
検出し、この運転状態と上記マップとの照合に基づき、
上記EGR弁開領域A1,A2では上記EGR弁36を
開き、かつその開度を図4のような特性で制御するとと
もに、O2 センサ37からの信号に基づき上記フィード
バック制御によりインジェクタ14からの燃料噴射量を
制御する。一方、上記EGR弁開領域A1,A2以外の
領域では、EGR弁36を閉じるとともに、オープン制
御によってインジェクタ14からの燃料噴射量を制御す
る。こうして上記ECU40により、制御弁コントロー
ル手段43と、空燃比コントロール手段44とが構成さ
れている(図5参照)。The control area map of FIG. 3 and E of FIG.
The map of the GR valve opening degree is stored in the ECU 40 in advance. Then, the ECU 40 detects the operating state based on the signals from the air flow meter 22, the rotation speed sensor 41, and the like, and based on the comparison between the operating state and the map,
In the EGR valve open regions A1 and A2, the EGR valve 36 is opened, and the opening thereof is controlled by the characteristic shown in FIG. 4, and the fuel from the injector 14 is controlled by the feedback control based on the signal from the O 2 sensor 37. Control the injection amount. On the other hand, in regions other than the EGR valve open regions A1 and A2, the EGR valve 36 is closed and the fuel injection amount from the injector 14 is controlled by open control. In this way, the ECU 40 constitutes the control valve control means 43 and the air-fuel ratio control means 44 (see FIG. 5).
【0023】このような当実施例の装置によると、低負
荷領域と過給領域の一部とを含む上記EGR弁開領域A
1,A2では、EGR弁36が開かれる。そして、上記
EGR領域A1では排気圧力が吸気圧力よりも高いため
に、EGRが行われ、これによりNOxが低減されると
ともに、空燃比が略理論空燃比となるようにフィードバ
ック制御が行われることにより、HC、CO等が触媒3
8により浄化され、排気浄化性能が良好に保たれる。According to the apparatus of this embodiment as described above, the EGR valve opening region A including the low load region and a part of the supercharging region.
In 1 and A2, the EGR valve 36 is opened. Since the exhaust pressure is higher than the intake pressure in the EGR region A1, EGR is performed, NOx is thereby reduced, and feedback control is performed so that the air-fuel ratio becomes substantially the stoichiometric air-fuel ratio. , HC, CO, etc. are catalysts 3
8 and the exhaust gas purification performance is kept good.
【0024】二次エア供給領域A2になると、吸気圧力
が排気圧力よりも高くなることにより、EGRが停止さ
れる代りに、二次エアがEGR通路35を通して排気通
路12の触媒38の上流に供給される。これとともに、
この二次エア供給状態で見掛け上の空燃比が理論空燃比
となるようにフィードバック制御されることにより、実
際の燃焼室内の空燃比はリッチにされる。燃焼室内の空
燃比がリッチにされるとNOx発生量が減少し、かつ、
上記二次エアの供給により触媒38の性能は良好に保た
れることから、この領域でも排気浄化性能が良好とな
る。In the secondary air supply region A2, the intake pressure becomes higher than the exhaust pressure, so that the EGR is stopped but the secondary air is supplied to the upstream of the catalyst 38 in the exhaust passage 12 through the EGR passage 35. To be done. With this,
In this secondary air supply state, feedback control is performed so that the apparent air-fuel ratio becomes the stoichiometric air-fuel ratio, so that the actual air-fuel ratio in the combustion chamber is made rich. When the air-fuel ratio in the combustion chamber is made rich, the NOx generation amount decreases, and
Since the performance of the catalyst 38 is kept good by the supply of the secondary air, the exhaust purification performance becomes good also in this region.
【0025】また、上記設定負荷Laより高負荷側で
は、EGR弁36が閉じられることにより、EGRおよ
び二次エア供給がともに停止され、過給気の全量が燃焼
室に供給されて掃気性、充填効率が高められる。また、
高負荷側で二次エアによる触媒温度および排気温度の過
度の上昇を招くという事態が防止される。さらにこの領
域では空燃比がリッチにされることでも排気温度の上昇
が抑制される。On the higher load side than the set load La, the EGR valve 36 is closed to stop both the EGR and the secondary air supply, and the entire amount of the supercharged air is supplied to the combustion chamber, so that scavenging, The filling efficiency is improved. Also,
A situation in which the catalyst temperature and the exhaust temperature are excessively increased by the secondary air on the high load side is prevented. Further, in this region, even if the air-fuel ratio is made rich, the rise in exhaust temperature is suppressed.
【0026】図6は本発明の別の実施例を示し、この実
施例では、排気通路12に、三元触媒からなる主触媒3
8に加え、NOx用補助触媒45が設けられており、主
触媒38より上流にEGR通路35が接続され、さらに
その上流に上記補助触媒45が配置されている。この実
施例でも、排気浄化装置全体の構造は図1に示したもの
と同様とし、かつEGR弁の制御および空燃比の制御も
前記の実施例と同様とすればよい。FIG. 6 shows another embodiment of the present invention. In this embodiment, the main catalyst 3 composed of a three-way catalyst is provided in the exhaust passage 12.
In addition to 8, the auxiliary catalyst 45 for NOx is provided, the EGR passage 35 is connected upstream of the main catalyst 38, and the auxiliary catalyst 45 is disposed further upstream thereof. Also in this embodiment, the structure of the entire exhaust purification system may be the same as that shown in FIG. 1, and the control of the EGR valve and the control of the air-fuel ratio may be the same as those in the above embodiments.
【0027】この実施例によると、EGR通路35が閉
じられてEGRおよび二次エア供給が停止される高負荷
領域でも、上記補助触媒45によりNOxが低減され
る。また、二次エア供給領域では、補助触媒45より下
流で主触媒38より上流に二次エアが供給されることに
より、それぞれの触媒機能が良好に発揮される。According to this embodiment, the auxiliary catalyst 45 reduces NOx even in the high load region where the EGR passage 35 is closed and the EGR and secondary air supply is stopped. Further, in the secondary air supply region, the secondary air is supplied downstream of the auxiliary catalyst 45 and upstream of the main catalyst 38, so that the respective catalytic functions are well exhibited.
【0028】なお、空燃比の制御として、前記の実施例
では、図3中の領域A1,A2のいずれにおいてもO2
センサ出力に応じたフィードバック制御を行うことによ
って二次エア領域A2では燃焼室内の空燃比がリッチに
なるようにしているが、二次エア領域ではオープン制御
によって理論空燃比よりもリッチな設定空燃比を与える
ように燃料を増量補正してもよい。As the control of the air-fuel ratio, in the above-mentioned embodiment, O 2 is applied to both the regions A1 and A2 in FIG.
The air-fuel ratio in the combustion chamber is made rich in the secondary air region A2 by performing feedback control according to the sensor output, but in the secondary air region, the set air-fuel ratio richer than the theoretical air-fuel ratio is made by open control. The fuel may be increased and corrected so that
【0029】[0029]
【発明の効果】本発明は、排気浄化用の触媒より上流の
排気通路と機械式過給機より下流の吸気通路との間に排
気ガス還流通路を接続する一方、過給領域における全負
荷より所定量低い設定負荷までの運転領域で上記排気ガ
ス還流通路の制御弁を開弁させ、かつ、過給機下流の吸
気圧力が排気圧力よりも低い運転領域では燃焼室内の混
合気の空燃比を略理論空燃比とし、上記吸気圧力が排気
圧力よりも高くなる領域では上記空燃比をリッチするよ
うに制御している。このため、上記設定負荷までの領域
のうちで上記吸気圧力が排気圧力よりも高い過給領域で
は、燃焼室内の空燃比をリッチにすることでNOxを低
減しつつ、EGR通路を利用して二次エアを排気通路の
触媒に供給し、排気浄化性能を向上することができる。
また、設定負荷以上の高負荷領域では、排気還流および
二次エア供給が停止されることにより、過給による掃気
を促進し、出力性能および耐ノック性を高めるとともに
排気温度の上昇を抑制することができる。According to the present invention, the exhaust gas recirculation passage is connected between the exhaust passage upstream of the catalyst for purification of exhaust gas and the intake passage downstream of the mechanical supercharger, while the exhaust gas recirculation passage is connected to the exhaust gas recirculation passage. The control valve of the exhaust gas recirculation passage is opened in an operating region up to a set load that is lower by a predetermined amount, and the air-fuel ratio of the air-fuel mixture in the combustion chamber is set in an operating region where the intake pressure downstream of the supercharger is lower than the exhaust pressure. The air-fuel ratio is set to a substantially stoichiometric ratio, and the air-fuel ratio is controlled to be rich in a region where the intake pressure is higher than the exhaust pressure. Therefore, in the supercharging region in which the intake pressure is higher than the exhaust pressure in the region up to the set load, NOx is reduced by making the air-fuel ratio in the combustion chamber rich, and the EGR passage is utilized. The secondary air can be supplied to the catalyst in the exhaust passage to improve the exhaust purification performance.
Also, in the high load range above the set load, exhaust gas recirculation and secondary air supply are stopped to promote scavenging due to supercharging, improve output performance and knock resistance, and suppress rise in exhaust temperature. You can
【0030】また、上記触媒を三元触媒とするととも
に、排気通路の排気ガス還流通路接続部より上流に、N
Ox用補助触媒を配置しておけば、高負荷領域等での排
気浄化性能も良好になる。Further, the above catalyst is a three-way catalyst, and N is provided upstream of the exhaust gas recirculation passage connecting portion of the exhaust passage.
By disposing the Ox auxiliary catalyst, the exhaust gas purification performance in the high load region and the like becomes good.
【0031】また、排気通路の排気ガス還流通路よりも
下流にO2 センサを具備する一方、上記空燃比コントロ
ール手段は、排気ガス還流通路の制御弁が開弁される運
転領域で上記O2 センサにより検出される見掛け上の空
燃比を略理論空燃比とするようにフィードバック制御す
るものとすれば、排気ガス還流が行われる領域では空燃
比を略理論空燃比とし二次エア供給が行われる領域では
空燃比をリッチする制御を、簡単かつ確実に行うことが
できる。Further, while an O 2 sensor is provided in the exhaust passage downstream of the exhaust gas recirculation passage, the air-fuel ratio control means has the O 2 sensor in an operating region where the control valve of the exhaust gas recirculation passage is opened. If feedback control is carried out so that the apparent air-fuel ratio detected by is approximately the stoichiometric air-fuel ratio, the air-fuel ratio is set to the substantially stoichiometric air-fuel ratio in the region where exhaust gas recirculation is performed and the air-fuel ratio is set in the region where secondary air supply is performed. The control for enriching the fuel ratio can be performed easily and reliably.
【図1】本発明の一実施例による排気ガス浄化装置を備
えた機械式過給機付エンジン全体の概略図である。FIG. 1 is a schematic view of an entire engine with a mechanical supercharger equipped with an exhaust gas purification device according to an embodiment of the present invention.
【図2】要部の構造説明図である。FIG. 2 is a structural explanatory view of a main part.
【図3】EGR弁およびインジェクタに対する制御領域
のマップを示す図である。FIG. 3 is a diagram showing a map of control regions for an EGR valve and an injector.
【図4】EGR弁開領域におけるEGR弁開度の制御特
性を示す図である。FIG. 4 is a diagram showing a control characteristic of an EGR valve opening degree in an EGR valve open region.
【図5】制御系統の機能ブロック図である。FIG. 5 is a functional block diagram of a control system.
【図6】別の実施例を示す要部の構造説明図である。FIG. 6 is a structural explanatory view of a main part showing another embodiment.
1 エンジン本体 11 吸気通路 12 排気通路 24 機械式過給機 35 EGR通路 36 EGR弁 38 触媒 40 ECU 43 制御弁コントロール手段 44 空燃比コントロール手段 1 Engine Body 11 Intake Passage 12 Exhaust Passage 24 Mechanical Supercharger 35 EGR Passage 36 EGR Valve 38 EGR Valve 38 Catalyst 40 ECU 43 Control Valve Control Means 44 Air-Fuel Ratio Control Means
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 FI 技術表示箇所 F02D 41/02 330 D 9039−3G 41/14 310 A 9039−3G F02M 25/07 550 G 8923−3G 570 P 8923−3G 580 Z 8923−3G ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification number Office reference number FI technical display location F02D 41/02 330 D 9039-3G 41/14 310 A 9039-3G F02M 25/07 550 G 8923- 3G 570 P 8923-3G 580 Z 8923-3G
Claims (3)
け、排気通路と吸気通路との間に排気ガス還流通路を接
続し、この通路中に制御弁を設けた機械式過給機付エン
ジンにおいて、排気浄化用の触媒より上流の排気通路と
機械式過給機より下流の吸気通路との間に排気ガス還流
通路を接続して、この排気ガス還流通路に作用する吸気
圧力が排気圧力よりも高くなる過給領域では排気ガス還
流通路を通して吸気通路から排気通路へ二次エアが導か
れるように構成する一方、低負荷から過給領域における
全負荷より所定量低い設定負荷までにわたる運転領域
で、上記排気ガス還流通路の制御弁を開弁させる制御弁
コントロール手段と、上記吸気圧力が排気圧力よりも低
い運転領域では燃焼室内の混合気の空燃比を略理論空燃
比とし、上記吸気圧力が排気圧力よりも高くなる領域で
は上記空燃比をリッチにする空燃比コントロール手段と
を備えたことを特徴とする機械式過給機付エンジンの排
気ガス浄化装置。1. A mechanical supercharger in which a mechanical supercharger is provided in an intake passage of an engine, an exhaust gas recirculation passage is connected between an exhaust passage and an intake passage, and a control valve is provided in the passage. In an engine, an exhaust gas recirculation passage is connected between an exhaust passage upstream of an exhaust purification catalyst and an intake passage downstream of a mechanical supercharger, and the intake pressure acting on this exhaust gas recirculation passage is the exhaust pressure. In the supercharging region, which is higher than the above, secondary air is guided from the intake passage to the exhaust passage through the exhaust gas recirculation passage, while operating region from low load to a set load that is a predetermined amount lower than the full load in the supercharging region. The control valve control means for opening the control valve of the exhaust gas recirculation passage and the air-fuel ratio of the air-fuel mixture in the combustion chamber in the operating region where the intake pressure is lower than the exhaust pressure are substantially stoichiometric air-fuel ratios. An exhaust gas purifying apparatus for an engine with a mechanical supercharger, comprising: an air-fuel ratio control means for making the air-fuel ratio rich in a region where is higher than the exhaust pressure.
気通路の排気ガス還流通路接続部より上流に、NOx用
補助触媒を配置した請求項1記載の機械式過給機付エン
ジンの排気ガス浄化装置。2. The exhaust gas of an engine with a mechanical supercharger according to claim 1, wherein the catalyst is a three-way catalyst, and an auxiliary catalyst for NOx is arranged upstream of the exhaust gas recirculation passage connecting portion of the exhaust passage. Purification device.
にO2 センサを具備する一方、上記空燃比コントロール
手段は、排気ガス還流通路の制御弁が開弁される運転領
域で上記O2 センサにより検出される見掛け上の空燃比
を略理論空燃比とするようにフィードバック制御するも
のである請求項1または2に記載の機械式過給機付エン
ジンの排気ガス浄化装置。3. An O 2 sensor is provided in the exhaust passage downstream of the exhaust gas recirculation passage, while the air-fuel ratio control means has the O 2 sensor in an operating region where a control valve of the exhaust gas recirculation passage is opened. The exhaust gas purifying apparatus for an engine with a mechanical supercharger according to claim 1 or 2, wherein feedback control is performed so that the apparent air-fuel ratio detected by the above is substantially stoichiometric air-fuel ratio.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3247956A JPH0586847A (en) | 1991-09-26 | 1991-09-26 | Exhaust emission control device for engine having mechanical supercharger |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP3247956A JPH0586847A (en) | 1991-09-26 | 1991-09-26 | Exhaust emission control device for engine having mechanical supercharger |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0586847A true JPH0586847A (en) | 1993-04-06 |
Family
ID=17171057
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP3247956A Pending JPH0586847A (en) | 1991-09-26 | 1991-09-26 | Exhaust emission control device for engine having mechanical supercharger |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0586847A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5845492A (en) * | 1995-09-18 | 1998-12-08 | Nippondenso Co., Ltd. | Internal combustion engine control with fast exhaust catalyst warm-up |
WO2004097190A1 (en) * | 2003-05-01 | 2004-11-11 | Yamaha Hatsudoki Kabushiki Kaisha | Engine |
JP2009002286A (en) * | 2007-06-22 | 2009-01-08 | Toyota Motor Corp | Exhaust recirculating device of internal combustion engine |
JP2010071217A (en) * | 2008-09-19 | 2010-04-02 | Nissan Motor Co Ltd | Exhaust emission control device for engine |
JP2014070530A (en) * | 2012-09-28 | 2014-04-21 | Daihatsu Motor Co Ltd | Internal combustion engine |
-
1991
- 1991-09-26 JP JP3247956A patent/JPH0586847A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5845492A (en) * | 1995-09-18 | 1998-12-08 | Nippondenso Co., Ltd. | Internal combustion engine control with fast exhaust catalyst warm-up |
US5974792A (en) * | 1995-09-18 | 1999-11-02 | Nippondenso Co., Ltd. | Internal combustion engine control with fast exhaust catalyst warm-up |
WO2004097190A1 (en) * | 2003-05-01 | 2004-11-11 | Yamaha Hatsudoki Kabushiki Kaisha | Engine |
JP2009002286A (en) * | 2007-06-22 | 2009-01-08 | Toyota Motor Corp | Exhaust recirculating device of internal combustion engine |
JP2010071217A (en) * | 2008-09-19 | 2010-04-02 | Nissan Motor Co Ltd | Exhaust emission control device for engine |
JP2014070530A (en) * | 2012-09-28 | 2014-04-21 | Daihatsu Motor Co Ltd | Internal combustion engine |
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