JP3006021B2 - Air-fuel ratio control device for internal combustion engine - Google Patents
Air-fuel ratio control device for internal combustion engineInfo
- Publication number
- JP3006021B2 JP3006021B2 JP2078221A JP7822190A JP3006021B2 JP 3006021 B2 JP3006021 B2 JP 3006021B2 JP 2078221 A JP2078221 A JP 2078221A JP 7822190 A JP7822190 A JP 7822190A JP 3006021 B2 JP3006021 B2 JP 3006021B2
- Authority
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- Prior art keywords
- bypass passage
- sensor
- exhaust
- passage
- internal combustion
- 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.)
- Expired - Lifetime
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- Exhaust Gas After Treatment (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は内燃機関の空燃比制御装置に係り、特に唯
一の排気センサにより触媒体の浄化機能の劣化状態を正
確に判断し得る内燃機関の空燃比制御装置に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control device for an internal combustion engine, and more particularly to an air-fuel ratio control device for an internal combustion engine capable of accurately judging a deterioration state of a purification function of a catalyst by a single exhaust sensor. The present invention relates to an air-fuel ratio control device.
〔従来の技術〕 内燃機関には、各種の運転状態において低燃料消費
率、少ない排気有害成分値等の要求を満足するために、
空燃比制御装置を設けたものがある。内燃機関の空燃比
制御装置は、例えば、第18図に示す如く構成されてい
る。図において、102は内燃機関、104はエアクリーナ、
106は吸気マニホルド、108は吸気通路、110は燃焼室、1
12は排気マニホルド、114は排気通路である。[Prior art] In order to satisfy demands such as a low fuel consumption rate and a low exhaust harmful component value in various operating states in an internal combustion engine,
Some have an air-fuel ratio control device. The air-fuel ratio control device for an internal combustion engine is configured, for example, as shown in FIG. In the figure, 102 is an internal combustion engine, 104 is an air cleaner,
106 is an intake manifold, 108 is an intake passage, 110 is a combustion chamber, 1
12 is an exhaust manifold, and 114 is an exhaust passage.
内燃機関102の吸気通路108には、燃焼室110に指向さ
せて燃料系を構成する燃料噴射弁116が設けられてい
る。この燃料噴射弁116は、燃料通路118により燃料タン
ク120内の燃料ポンプ122に連通されている。燃料通路11
8の途中には、燃料タンク120側から順次にフィルタ124
と圧力調整弁126とが設けられている。燃料噴射弁116
は、燃料ポンプ122により燃料通路118に圧送され、フィ
ルタ124により塵埃を除去され、圧力調整弁126により所
定圧に調整された燃料を、燃焼室110に噴射供給する。
なお、符号128は、燃料戻り通路である。In an intake passage 108 of the internal combustion engine 102, a fuel injection valve 116 that constitutes a fuel system is provided so as to be directed to the combustion chamber 110. The fuel injection valve 116 is connected to a fuel pump 122 in a fuel tank 120 by a fuel passage 118. Fuel passage 11
In the middle of 8, the filter 124 is sequentially arranged from the fuel tank 120 side.
And a pressure regulating valve 126 are provided. Fuel injection valve 116
The fuel is pressure-fed to the fuel passage 118 by the fuel pump 122, dust is removed by the filter 124, and the fuel adjusted to a predetermined pressure by the pressure adjusting valve 126 is injected and supplied to the combustion chamber 110.
Reference numeral 128 denotes a fuel return passage.
前記燃料噴射弁116は、制御手段である制御部130に接
続されている。この制御部130には、燃料噴射量を制御
するための制御因子信号を入力するセンサ類として、例
えば、吸入空気量を検出するエアフローメータ132と、
図示しないクランク角を検出するクランク角センサ134
と、図示しないスロットルバルブの開度を検出するスロ
ットルセンサ136と、内燃機関102の冷却水温度を検出す
る水温センサ138と、機関回転数を検出すべくイグニシ
ョンコイル140のパワーユニット142と、排気中の排気成
分値を検出する排気センサたるO2センサ144と、等が接
続されている。The fuel injection valve 116 is connected to a control unit 130 as control means. The control unit 130 includes sensors that input a control factor signal for controlling the fuel injection amount, for example, an air flow meter 132 that detects an intake air amount,
Crank angle sensor 134 for detecting a crank angle (not shown)
A throttle sensor 136 for detecting an opening degree of a throttle valve (not shown), a water temperature sensor 138 for detecting a cooling water temperature of the internal combustion engine 102, a power unit 142 of an ignition coil 140 for detecting an engine speed, and an exhaust sensor serving O 2 sensor 144 for detecting an exhaust component values, etc. are connected.
制御部130は、これらセンサ類132〜144の検出信号を
入力して燃料噴射量を演算し、燃料噴射量に応じて前記
燃料噴射弁116を動作制御して燃焼室110に燃料を噴射供
給し、内燃機関102の要求する空燃比に制御する。The control unit 130 inputs the detection signals of these sensors 132 to 144 to calculate the fuel injection amount, controls the operation of the fuel injection valve 116 according to the fuel injection amount, and injects and supplies the fuel to the combustion chamber 110. , The air-fuel ratio required by the internal combustion engine 102 is controlled.
また、制御部130は、O2センサ144の検出信号により内
燃機関102の空燃比を目標空燃比に制御し、排気通路114
に設けた触媒体146により排気を浄化する。The control unit 130, the air-fuel ratio of the internal combustion engine 102 is controlled to the target air-fuel ratio by detecting the signal of the O 2 sensor 144, the exhaust passage 114
The exhaust gas is purified by the catalyst body 146 provided in the above.
このようなO2センサ144の検出信号により内燃機関102
の空燃比を目標空燃比に制御し、排気通路114に設けた
触媒体146により排気を浄化する空燃比制御装置として
は、特開昭63−97846号公報に開示のものがある。この
公報に開示のものは、触媒体の上流側排気通路と下流側
排気通路とに夫々第１・第２のO2センサを設け、第２の
O2センサの検出信号がリーンである場合の制御定数更新
割合をリッチである場合の制御定数更新割合よりも大と
し、この第２のO2センサの検出信号による制御定数と第
１のO2センサの検出信号とにより空燃比を補正制御する
ことにより制御空燃比をリッチ側にし、触媒体の浄化機
能を高めたものである。Internal combustion engine 102 by the detection signal of such O 2 sensor 144
Japanese Patent Application Laid-Open No. 63-97846 discloses an air-fuel ratio control device that controls the air-fuel ratio of the exhaust gas to a target air-fuel ratio and purifies the exhaust gas by a catalyst 146 provided in the exhaust passage 114. In the device disclosed in this publication, first and second O 2 sensors are provided in an upstream exhaust passage and a downstream exhaust passage of a catalyst body, respectively.
The control constant update rate when the detection signal of the O 2 sensor is lean is larger than the control constant update rate when the detection signal is rich, and the control constant based on the detection signal of the second O 2 sensor and the first O 2 The air-fuel ratio is corrected and controlled based on the detection signal of the sensor, whereby the control air-fuel ratio is made rich and the purification function of the catalyst is enhanced.
また、触媒体により排気を浄化する燃料供給制御装置
としては、特開昭60−27756号公報に開示のものがあ
る。この公報に開示のものは、燃料遮断機能を備えた内
燃機関において、触媒体の触媒床温度が所定値以下とな
った際に、前記燃料遮断機能による燃料の遮断を停止し
て、触媒体の触媒床温度の低下による浄化機能の低下を
回避するものである。As a fuel supply control device for purifying exhaust gas with a catalyst, there is one disclosed in Japanese Patent Application Laid-Open No. Sho 60-27756. In the internal combustion engine having a fuel cutoff function, when the catalyst bed temperature of the catalyst body falls below a predetermined value, shutoff of fuel by the fuel cutoff function is stopped, and This is to avoid a decrease in the purification function due to a decrease in the catalyst bed temperature.
ところで、触媒体は、経年的変化等により浄化機能の
劣化を招くことがある。このように浄化機能の劣化した
触媒体が使用されると、徒に排気有害成分が大気中に放
出され、大気の汚染を回避できないことになる。By the way, the catalyst body may cause deterioration of the purification function due to aging or the like. When a catalyst having a deteriorated purification function is used, exhaust harmful components are released into the air, and it is impossible to avoid pollution of the air.
そこで、例えば、第９図に示す如く、排気通路114に
設けた触媒体146の上流側排気通路114−１と下流側排気
通路114−２とに夫々第１・第２のO2センサ144−１・14
4−２を設け、こられ第１・第２のO2センサ144−１・14
4−２の検出信号の出力を一定の条件下において比較し
て触媒体146の劣化状態を判断するものがある。Thus, for example, as shown in FIG. 9, the first and second O 2 sensors 144-1 are provided respectively in the upstream exhaust passage 114-1 and the downstream exhaust passage 114-2 of the catalyst body 146 provided in the exhaust passage 114. 1.14
4-2, and the first and second O 2 sensors 144-1 and 14-14 are provided.
In some cases, the output of the detection signal of 4-2 is compared under certain conditions to determine the deterioration state of the catalyst body 146.
例えば、第１のO2センサ144−１の検出信号の出力が
第10図に示す如き出力波形であるのに対して、第２のO2
センサ144−２の検出信号の出力が第11図に示す如き出
力波形である場合は、触媒体146により浄化が行われて
いることにより劣化状態が小であると判断する。一方、
第１のO2センサ144−１の検出信号の出力が第12図に示
す如き出力波形であるのに対して、第２のO2センサ144
−２の検出信号の出力が第13図に示す如き出力波形であ
る場合は、触媒体146により浄化が行われていないこと
により劣化状態が大であると判断する。For example, while the output of the first detection signal of the O 2 sensor 144-1 is such an output waveform shown in FIG. 10, the second O 2
When the output of the detection signal of the sensor 144-2 has an output waveform as shown in FIG. 11, it is determined that the deterioration state is small because the purification is performed by the catalyst 146. on the other hand,
While the output of the first detection signal of the O 2 sensor 144-1 is such an output waveform shown in FIG. 12, a second O 2 sensor 144
When the output of the detection signal of −2 has an output waveform as shown in FIG. 13, it is determined that the deterioration state is large because the catalyst 146 has not been purified.
あるいは、排気通路114に設けた触媒体146の上流側排
気通路114−１と下流側排気通路114−２とに夫々設けた
第１・第２のO2センサ144−１・144−２との各検出信号
の応答時間を、一定の条件下において比較して触媒体14
6の劣化状態を判断するものがある。Alternatively, the first and second O 2 sensors 144-1 and 144-2 provided in the upstream exhaust passage 114-1 and the downstream exhaust passage 114-2 of the catalyst body 146 provided in the exhaust passage 114, respectively. The response time of each detection signal is compared under certain conditions to
There is one that determines the deterioration state of 6.
即ち、第14図に示す如き第１のO2センサ144−１の検
出信号の応答時間、つまり0Vから所定値（例えば、0.45
V）に達するまでの応答時間t1と、第15図に示す如き第
２のO2センサ144−２の検出信号の応答時間t2とを比較
し、t1＜t2である場合は劣化状態が小であると判断し、
一方、t1≒t2である場合は劣化状態が大であると判断す
る。That is, the response time of the 14 detection signals of the first O 2 sensor 144-1 as shown in FIG., That is a predetermined value from 0V (for example, 0.45
And response time t1 to reach V), in comparing the response time t2 of the detection signal of the second O 2 sensor 144-2 as shown in FIG. 15, t1 <case of t2 is deteriorated state small Judge that there is,
On the other hand, if t1 ≒ t2, it is determined that the deterioration state is large.
また、第16図に示す如く、排気通路114に設けた触媒
体146に温度センサ148を設け、触媒体温度により触媒体
146の劣化状態を判断するものがある。As shown in FIG. 16, a temperature sensor 148 is provided on a catalyst body 146 provided in the exhaust passage 114, and the temperature of the catalyst body is determined by the temperature of the catalyst body.
There is one that determines the deterioration state of 146.
つまり、劣化していない触媒体146は、触媒体146内に
おいて燃焼が行われることにより触媒体温度が高い。し
たがって、劣化している触媒体146は、触媒体146内にお
いて充分に燃焼が行われないことにより触媒体温度が下
がる。そこで、第17図に示す如く、温度センサ148の検
出する触媒体146の触媒体温度が高い温度のTemp.1であ
る場合は劣化状態が小であると判断し、一方、触媒体14
6の触媒体温度が低い温度のTemp.2である場合は劣化状
態が大であると判断する。In other words, the catalyst body 146 which has not deteriorated has a high catalyst body temperature due to combustion in the catalyst body 146. Therefore, the temperature of the deteriorated catalyst body 146 decreases because the combustion in the catalyst body 146 is not sufficiently performed. Therefore, as shown in FIG. 17, when the catalyst body temperature of the catalyst body 146 detected by the temperature sensor 148 is Temp.1, which is a high temperature, it is determined that the deterioration state is small.
In the case where the temperature of the catalyst body of No. 6 is the low temperature Temp.2, it is determined that the deterioration state is large.
ところが、前記如く第１・第２のO2センサを設けて検
出信号の出力や応答時間を比較して触媒体の劣化状態を
判断するものは、２つのO2センサを設けていることによ
りコストの上昇を招く不都合がある。また、２つのO2セ
ンサ自体の検出精度のばらつきや、２つのO2センサ自体
の劣化状態に相違を生じることにより、正確な判断をな
し得ず、誤判断を下す不都合がある。However, as described above, the provision of the first and second O 2 sensors and comparing the output of the detection signal and the response time to determine the deterioration state of the catalyst body is costly due to the provision of the two O 2 sensors. There is a disadvantage that leads to an increase in Further, variation in detection accuracy of the two O 2 sensors themselves and, by generating a difference in two deterioration of the O 2 sensor itself, not give no accurate judgment, there is a disadvantage to make a misjudgment.
また、前記の如く温度センサを設けて触媒体温度によ
り触媒体の劣化状態を判断するものは、触媒体の温度が
周囲の温度環境の影響を受け易いことにより、正確な判
断をなし得ず、誤判断を下す不都合がある。Further, in the case where the temperature sensor is provided to determine the deterioration state of the catalyst body based on the temperature of the catalyst body as described above, the temperature of the catalyst body is easily affected by the surrounding temperature environment, so that accurate determination cannot be made. There is an inconvenience of making a misjudgment.
そこでこの発明の目的は、唯一の排気センサにより触
媒体の浄化機能の劣化状態を判断することにより、排気
センサの検出精度のばらつきや排気センサ自体の劣化状
態の相違、また、周囲の温度環境の影響等の影響を受け
ることなく触媒体の劣化状態を正確に判断し得て、２つ
の排気センサを要せず唯一の排気センサにより判断し得
ることによりコストを低減し得る内燃機関の空燃比制御
装置を実現することにある。Accordingly, an object of the present invention is to determine the deterioration state of the purifying function of the catalyst using only one exhaust sensor, thereby making it possible to vary the detection accuracy of the exhaust sensor, the deterioration state of the exhaust sensor itself, and the ambient temperature environment. Air-fuel ratio control of an internal combustion engine that can accurately judge the deterioration state of the catalyst body without being affected by the influence, and can reduce cost by being able to judge with only one exhaust sensor without requiring two exhaust sensors It is to implement the device.
この目的を達成するために、この発明は、内燃機関の
排気通路に設けた触媒体の上流側排気通路の第１分岐部
に始端側を連通する第１路バイパス通路を設けるととも
に前記触媒体の下流側排気通路の第２分岐部に始端側を
連通する第２路バイパス通路を設け、前記第１バイパス
通路及び第２バイパス通路の各終端側を集合部において
集合して集合バイパス通路の始端側に連通して設け、こ
の集合バイパス通路の終端側を前記第２分岐部よりも下
流側の排気通路の合流部に連通させて設け、前記第１バ
イパス通路及び第２バイパス通路を前記集合バイパス通
路に選択的に切換連通させる切換弁を前記集合部に設け
るとともに前記集合バイパス通路に唯一の排気センサを
設け、前記切換弁により前記第１バイパス通路を前記集
合バイパス通路に切換連通させた状態における前記排気
センサの検出信号により前記内燃機関の空燃比を目標空
燃比に制御するとともに、前記内燃機関の所定運転状態
において前記切換弁により前記第１バイパス通路を前記
集合バイパス通路に切換連通させた状態における前記排
気センサの検出信号と前記切換弁により前記第２バイパ
ス通路を前記集合バイパス通路に切換連通させた状態に
おける前記排気センサの検出信号とを比較して前記触媒
体の劣化状態を判断する制御手段を設けたことを特徴と
する。In order to achieve this object, the present invention provides a first passage bypass passage that communicates a starting end with a first branch portion of an upstream exhaust passage of a catalyst body provided in an exhaust passage of an internal combustion engine, and provides a first passage bypass passage for the catalyst body. A second path bypass passage is provided for communicating the start end side to the second branch portion of the downstream side exhaust passage, and the terminal ends of the first bypass passage and the second bypass passage are gathered at the gathering part and the start side of the gathering bypass passage is provided. And a terminal end of the collective bypass passage is provided so as to communicate with a junction of an exhaust passage downstream of the second branch portion, and the first bypass passage and the second bypass passage are connected to the collective bypass passage. A switching valve for selectively switching communication between the first bypass passage and the collective bypass passage; and a single exhaust sensor provided in the collective bypass passage. The air-fuel ratio of the internal combustion engine is controlled to a target air-fuel ratio by a detection signal of the exhaust sensor in the communication state, and the first bypass passage is connected to the collective bypass passage by the switching valve in a predetermined operation state of the internal combustion engine. The detection signal of the exhaust sensor in the state of the switching communication is compared with the detection signal of the exhaust sensor in the state of switching the second bypass passage to the collective bypass passage by the switching valve, and the catalyst body is deteriorated. A control means for judging a state is provided.
この発明の構成によれば、制御手段によって、切換弁
により第１バイパス通路を集合バイパス通路に切換連通
させた状態における排気センサの検出信号により内燃機
関の空燃比を目標空燃比に制御するとともに、内燃機関
の所定運転状態において切換弁により第１バイパス通路
を集合バイパス通路に切換連通させた状態における排気
センサの検出信号と切換弁により第２バイパス通路を集
合バイパス通路に切換連通させた状態における排気セン
サの検出信号とを比較して触媒体の劣化状態を判断する
ので、唯一の排気センサにより触媒体の浄化機能の劣化
状態を判断することができる。According to the configuration of the present invention, the control unit controls the air-fuel ratio of the internal combustion engine to the target air-fuel ratio based on the detection signal of the exhaust sensor in a state where the first bypass passage is switched to the collective bypass passage by the switching valve. In a predetermined operating state of the internal combustion engine, a detection signal of an exhaust sensor in a state in which the first bypass passage is switched to the collective bypass passage by the switching valve and an exhaust gas in a state in which the second bypass passage is switched to the collective bypass passage by the switching valve. Since the deterioration state of the catalyst body is determined by comparing with the detection signal of the sensor, it is possible to determine the deterioration state of the purification function of the catalyst body by using only one exhaust sensor.
次にこの発明の実施例を図に基づいて詳細に説明す
る。Next, an embodiment of the present invention will be described in detail with reference to the drawings.
第１〜８図は、この発明の実施例を示すものである。
第１図において、２は内燃機関、４は吸気マニホルド、
６は吸気通路、８は排気マニホルド、10は排気通路、12
は触媒体である。1 to 8 show an embodiment of the present invention.
In FIG. 1, 2 is an internal combustion engine, 4 is an intake manifold,
6 is an intake passage, 8 is an exhaust manifold, 10 is an exhaust passage, 12
Is a catalyst.
前記内燃機関２には、図示しない燃料噴射弁等の燃料
供給系が設けられている。吸気通路４から吸気マニホル
ド６を介して内燃機関２に供給された燃料は、燃焼して
排気マニホルド８から排気通路10に排出され、触媒体12
により浄化されて外部に排出される。The internal combustion engine 2 is provided with a fuel supply system such as a fuel injection valve (not shown). Fuel supplied from the intake passage 4 to the internal combustion engine 2 via the intake manifold 6 is burned and discharged from the exhaust manifold 8 to the exhaust passage 10, and the catalyst 12
And is discharged to the outside.
この触媒体12の上流側排気通路10−１の第１分岐部14
に始端側を連通する第１路バイパス通路16を設けるとと
もに、前記触媒体12の下流側排気通路10−２の第２分岐
部18に始端側を連通する第２路バイパス通路20を設け
る。The first branch portion 14 of the exhaust passage 10-1 on the upstream side of the catalyst 12
In addition to the first passage bypass passage 16 communicating the start end side, a second passage bypass passage 20 communicating the start end side to the second branch portion 18 of the downstream exhaust passage 10-2 of the catalyst 12 is provided.
前記第１バイパス通路16及び第２バイパス通路20の各
終端側は、集合部22において集合して集合バイパス通路
24の始端側に連通して設ける。このバイパス通路24の終
端側は、第２の分岐部18よりも下流側の排気通路10の合
流部26に連通させて設ける。The respective terminal sides of the first bypass passage 16 and the second bypass passage 20 are gathered at the gathering portion 22 to form a combined bypass passage.
Provided in communication with the starting end of 24. The terminal side of the bypass passage 24 is provided so as to communicate with the junction 26 of the exhaust passage 10 downstream of the second branch portion 18.
第２図に示す如く、前記集合部22には、第１バイパス
通路16及び第２バイパス通路20を集合バイパス通路24に
選択的に切換連通させる切換弁28を設ける。また、前記
集合バイパス通路24には、唯一の排気センサたるO2セン
サ30を設ける。As shown in FIG. 2, the collecting portion 22 is provided with a switching valve 28 for selectively switching the first bypass passage 16 and the second bypass passage 20 to the collecting bypass passage 24. Moreover, the the set bypass passage 24 is provided with a sole exhaust sensor serving O 2 sensor 30.
前記切換弁28は、弁体32と、弁軸34と、弁レバー36
と、戻しバネ38と、を有し、弁レバー36を索体40により
アクチュエータ42に接続している。このアクチュエータ
42は、前記O2センサ30とともに制御手段たる制御部44に
接続されている。なお、切換弁28による第１バイパス通
路16及び第２バイパス通路20の集合バイパス通路24に対
する切換連通は、排気の漏れを生じないように気密に切
換えられる。The switching valve 28 includes a valve body 32, a valve shaft 34, and a valve lever 36.
And a return spring 38, and the valve lever 36 is connected to the actuator 42 by a cord 40. This actuator
42 is connected to the control means serving controller 44 together with the O 2 sensor 30. The switching communication between the first bypass passage 16 and the second bypass passage 20 to the collective bypass passage 24 by the switching valve 28 is airtightly switched so as not to cause leakage of exhaust gas.
制御部44には、制御因子信号を入力するセンサ類とし
て、例えば、内燃機関２の冷却水温度を検出する水温セ
ンサ46と、吸気圧たる負圧を検出する圧力センサ48と、
機関回転数を検出する回転数センサ50と、車速を検出す
る車速センサ52と、が接続されている。また、この制御
部44には、ダイアグノーシスランプ54が接続されてい
る。The control unit 44 includes, as sensors for inputting control factor signals, for example, a water temperature sensor 46 for detecting a cooling water temperature of the internal combustion engine 2, a pressure sensor 48 for detecting a negative pressure as an intake pressure,
A rotation speed sensor 50 for detecting the engine speed and a vehicle speed sensor 52 for detecting the vehicle speed are connected. A diagnosis lamp 54 is connected to the control unit 44.
制御部44は、これらセンサ類30・46〜52の検出信号を
入力し、燃料供給系を制御して内燃機関２の要求する空
燃比に制御する。The control unit 44 receives the detection signals of these sensors 30 and 46 to 52 and controls the fuel supply system to control the air-fuel ratio required by the internal combustion engine 2.
また、制御部44は、切換弁28により第１バイパス通路
16を集合バイパス通路24に切換連通させた状態における
O2センサ30の検出信号により内燃機関２の空燃比を目標
空燃比に制御するとともに、内燃機関２の所定運転状態
において、例えば、水温が80〜90℃（Δ５℃）、負圧が
−450〜−500mmHg（Δ−10mmHg）、機関回転数が2500〜
3000rpm（Δ200rpm）、車速が50〜60km/h（Δ5km/h）等
の運転状態において、切換弁28により第１バイパス通路
16を集合バイパス通路24に切換連通させた状態における
O2センサ30の検出信号と、内燃機関２の所定運転状態に
おいて切換弁28により第２バイパス通路20を集合バイパ
ス通路24に切換連通させた状態におけるO2センサ30の検
出信号とを比較し、触媒体12の劣化状態を判断するもの
である。Further, the control unit 44 controls the first bypass passage by the switching valve 28.
16 in the state of being switched to the collective bypass passage 24
The detection signal of the O 2 sensor 30 to control the air-fuel ratio of the internal combustion engine 2 to the target air-fuel ratio in a predetermined operating state of the internal combustion engine 2, for example, water temperature is 80~90 ℃ (Δ5 ℃), the negative pressure -450 ~ -500mmHg (Δ-10mmHg), engine speed 2500 ~
In an operating state such as 3000 rpm (Δ200 rpm) and a vehicle speed of 50 to 60 km / h (Δ5 km / h), the first bypass passage is switched by the switching valve 28.
16 in the state of being switched to the collective bypass passage 24
O 2 compares the detection signal of the sensor 30, and a detection signal of the O 2 sensor 30 in the state where the through switching換連the second bypass passage 20 to the set bypass passage 24 by switching valve 28 in a predetermined operating state of the internal combustion engine 2, This is for determining the state of deterioration of the catalyst body 12.
次に作用を説明する。 Next, the operation will be described.
内燃機関２の通常の運転状態においては、第３図に示
す如く、制御部44によりアクチュエータ42を作動させ、
切換弁28により第１バイパス通路16を集合バイパス通路
24に切換連通させている。この状態において、制御部44
は、O2センサ30の検出信号により内燃機関２の空燃比を
目標空燃比に制御する。In a normal operation state of the internal combustion engine 2, as shown in FIG.
The first bypass passage 16 is collected by the switching valve 28.
Switch communication with 24. In this state, the control unit 44
Controls the air-fuel ratio of the internal combustion engine 2 to the target air-fuel ratio by detecting signals of the O 2 sensor 30.
また、制御部44は、内燃機関２の所定運転状態におい
て、第３図に示す如く切換弁28により第１バイパス通路
16を集合バイパス通路24に切換連通させた状態における
O2センサ30の検出信号と、第４図に示す如く切換弁28に
より第２バイパス通路20を集合バイパス通路24に切換連
通させた状態におけるO2センサ30の検出信号とを比較
し、触媒体12の劣化状態を判断する。Further, in a predetermined operation state of the internal combustion engine 2, the control unit 44 controls the first bypass passage by the switching valve 28 as shown in FIG.
16 in the state of being switched to the collective bypass passage 24
O 2 and the detection signal of the sensor 30, compares the detection signal of the O 2 sensor 30 in the state where the through switching換連by switching valve 28 as shown in FIG. 4 the second bypass passage 20 to the set bypass passage 24, the catalyst body The deterioration state of 12 is determined.
例えば、内燃機関２の所定運転状態として、水温が80
〜90℃（Δ５℃）、負圧が−450〜−500mmHg（Δ−10mm
Hg）、機関回転数が2500〜3000rpm（Δ200rpm）、車速
が50〜60km/h（Δ5km/h）の運転状態となって安定して
いる運転状態において、第３図に示す如く切換弁28によ
り第１バイパス通路16を集合バイパス通路24に切換連通
させる。この状態における触媒体12を通過する以前の第
１バイパス通路16の排気によるO2センサ30の検出信号を
所定時間だけ制御部44に取込んで記憶する。For example, as the predetermined operation state of the internal combustion engine 2, the water temperature is 80
~ 90 ℃ (Δ5 ℃), negative pressure is -450 ~ -500mmHg (Δ-10mm
Hg), in an operating state where the engine speed is 2500 to 3000 rpm (Δ200 rpm) and the vehicle speed is 50 to 60 km / h (Δ5 km / h) and is stable, the switching valve 28 is used as shown in FIG. The first bypass passage 16 is switched to communicate with the collective bypass passage 24. In this state, the detection signal of the O 2 sensor 30 due to the exhaust of the first bypass passage 16 before passing through the catalyst body 12 is taken into the control unit 44 for a predetermined time and stored.
所定時間経過した後に、第４図に示す如く切換弁28に
より第２バイパス通路20を集合バイパス通路24に切換連
通させる。この状態における触媒体12を通過した後の第
２バイパス通路20の排気によるO2センサ30の検出信号を
制御44に取込む。After a lapse of a predetermined time, the second bypass passage 20 is switched to the collective bypass passage 24 by the switching valve 28 as shown in FIG. In this state, the detection signal of the O 2 sensor 30 due to the exhaust of the second bypass passage 20 after passing through the catalyst body 12 is taken into the control 44.
制御部44は、記憶している第１バイパス通路16の排気
によるO2センサ30の検出信号と現在検出している第２バ
イパス通路20の排気によるO2センサ30の検出信号とを比
較し、触媒体12の劣化状態を判断する。これにより、所
定時間内において、触媒体12の劣化状態の判断が行われ
る。The control unit 44 compares the stored detection signal of the O 2 sensor 30 due to the exhaust of the first bypass passage 16 with the currently detected detection signal of the O 2 sensor 30 due to the exhaust of the second bypass passage 20, The deterioration state of the catalyst body 12 is determined. As a result, the deterioration state of the catalyst body 12 is determined within the predetermined time.
触媒体12の劣化状態の判断は、以下の如く行われる。 The determination of the deterioration state of the catalyst body 12 is performed as follows.
所定運転状態において、切換弁28により第１バイパス
通路16を集合バイパス通路24に切換連通させた状態にお
ける第１バイパス通路16の排気によるO2センサ30の検出
信号の出力が第５図に示す如き出力波形であるのに対し
て、所定運転状態において、切換弁28により第２バイパ
ス通路20を集合バイパス通路24に切換連通させた状態に
おけるO2センサ30の検出信号の出力が第６図に示す如き
出力波形である場合は、触媒体12により浄化が行われて
いることにより劣化状態が小であると判断する。In a predetermined operation state, the output of the detection signal of the O 2 sensor 30 by the exhaust of the first bypass passage 16 in a state where the first bypass passage 16 is switched to the collective bypass passage 24 by the switching valve 28 as shown in FIG. FIG. 6 shows the output of the detection signal of the O 2 sensor 30 in a state where the second bypass passage 20 is switched to the collective bypass passage 24 by the switching valve 28 in the predetermined operation state, in contrast to the output waveform. In the case of such an output waveform, it is determined that the deterioration state is small because the purification is performed by the catalyst 12.
一方、所定運転状態において、切換弁28により第１バ
イパス通路16を集合バイパス通路24に切換連通させた状
態における第１バイパス通路16の排気によるO2センサ30
の検出信号の出力が第７図に示す如き出力波形であるの
に対して、所定運転状態において、切換弁28により第２
バイパス通路20を集合バイパス通路24に切換連通させた
状態におけるO2センサ30の検出信号の出力が第８図に示
す如き出力波形である場合は、触媒体12により浄化が行
われていることにより劣化状態が大であると判断する。
触媒体12の劣化状態が大であると判断した場合は、ダイ
アグノーシスランプ54を点灯させる。On the other hand, in a predetermined operation state, the O 2 sensor 30 by the exhaust of the first bypass passage 16 in a state where the first bypass passage 16 is switched to the collective bypass passage 24 by the switching valve 28.
7 has an output waveform as shown in FIG.
When the output of the detection signal of the O 2 sensor 30 has the output waveform as shown in FIG. 8 in a state where the bypass passage 20 is switched to the collective bypass passage 24, the purification is performed by the catalyst body 12. It is determined that the deterioration state is large.
When it is determined that the state of deterioration of the catalyst 12 is large, the diagnosis lamp 54 is turned on.
このように、制御部44によって、内燃機関２の所定運
転状態において、切換弁28により第１バイパス通路16を
集合バイパス通路24に切換連通させた状態におけるO2セ
ンサ30の検出信号と、切換弁28により第２バイパス通路
20を集合バイパス通路24に切換連通させた状態における
O2センサ30の検出信号とを比較し、触媒体12の劣化状態
を判断するので、唯一のO2センサ30により触媒体12の浄
化機能の劣化状態を判断することができる。In this manner, the control unit 44 controls the detection signal of the O 2 sensor 30 in a state in which the first bypass passage 16 is switched to the collective bypass passage 24 by the switching valve 28 in a predetermined operation state of the internal combustion engine 2, and the switching valve. Second bypass passage by 28
20 in the state of being switched to the collective bypass passage 24
Since the deterioration state of the catalyst 12 is determined by comparing the detection signal of the O 2 sensor 30 with the detection signal, the deterioration state of the purification function of the catalyst 12 can be determined by the single O 2 sensor 30.
このため、従来の２つのO2センサによる触媒体の劣化
状態の判断ではO2センサ自体の検出精度のばらつきの影
響により正確な判断をなし得ない不都合があったが、唯
一のO2センサ30により触媒体12の浄化機能の劣化状態を
判断することによりO2センサの検出精度のばらつきの影
響を排除して正確な判断を行うことができる。また、従
来の２つのO2センサによる触媒体の劣化状態の判断で
は、経年変化等に起因する２つのO2センサの劣化状態の
相違の影響により正確な比較をなし得ない不都合があっ
たが、唯一のO2センサ30により触媒体12の浄化機能の劣
化状態を判断することにより２つのO2センサの劣化状態
の相違の影響を排除して正確な判断を行うことができ
る。さらに、触媒体12の触媒体温度による判断の如き周
囲の温度環境の影響を排除することができる。Therefore, in the determination of two conventional O 2 deteriorated state of the catalytic body according to the sensor there is an inconvenience which can not without an accurate determination due to the influence of variations in the detection accuracy of the O 2 sensor itself, only O 2 sensor 30 By judging the deterioration state of the purification function of the catalyst 12, the influence of the variation in the detection accuracy of the O 2 sensor can be eliminated to make an accurate judgment. Further, in the determination of two conventional O 2 deteriorated state of the catalytic body by a sensor, but there is an inconvenience which can not form a precise comparison due to the effect of the difference in the deterioration state of the two O 2 sensors due to aging or the like By judging the deterioration state of the purifying function of the catalyst 12 using only one O 2 sensor 30, the influence of the difference between the deterioration states of the two O 2 sensors can be eliminated to make an accurate judgment. Further, the influence of the surrounding temperature environment, such as the judgment based on the catalyst body temperature of the catalyst body 12, can be eliminated.
この結果、従来の２つのO2センサを設けた場合のよう
にO2センサ自体の検出精度のばらつきやO2センサの劣化
状態の相違の影響、また、周囲の温度環境の影響等を受
けることなく触媒体12の劣化状態を正確に判断すること
ができ、２つのO2センサを要せず唯一のO2センサによっ
て判断し得るのでコストを低減することができる。As a result, as in the case where two conventional O 2 sensors are provided, there is a difference in the detection accuracy of the O 2 sensor itself, the influence of the difference in the deterioration state of the O 2 sensor, the influence of the surrounding temperature environment, etc. without the deteriorated state of the catalytic body 12 can be accurately determined, the cost can be reduced because it can be determined by only the O 2 sensor without requiring two O 2 sensors.
このように、この発明によれば、制御手段によって、
切換弁により第１バイパス通路を集合バイパス通路に切
換連通させた状態における排気センサの検出信号により
内燃機関の空燃比を目標空燃比に制御するとともに、内
燃機関の所定運転状態において切換弁により第１バイパ
ス通路を集合バイパス通路に切換連通させた状態におけ
る排気センサの検出信号と切換弁により第２バイパス通
路を集合バイパス通路に切換連通させた状態における排
気センサの検出信号とを比較して触媒体の劣化状態を判
断するので、唯一の排気センサにより触媒体の浄化機能
の劣化状態を判断することができる。Thus, according to the present invention, by the control means,
The air-fuel ratio of the internal combustion engine is controlled to the target air-fuel ratio by the detection signal of the exhaust sensor in a state where the first bypass passage is switched to the collective bypass passage by the switching valve, and the first valve is operated by the switching valve in a predetermined operation state of the internal combustion engine. The detection signal of the exhaust sensor when the bypass passage is switched to the collective bypass passage is compared with the detection signal of the exhaust sensor when the second bypass passage is switched to the collective bypass passage by the switching valve. Since the deterioration state is determined, it is possible to determine the deterioration state of the purification function of the catalyst using only one exhaust sensor.
このため、従来の２つの排気センサを設けた場合のよ
うに排気センサ自体の検出精度のばらつきや排気センサ
の劣化状態の相違の影響、また、周囲の温度環境の影響
等を受けることなく触媒体の劣化状態を正確に判断し得
て、２つの排気センサを要せず唯一の排気センサにより
判断し得ることによりコストを低減し得る。Therefore, unlike the case where two conventional exhaust sensors are provided, the catalyst body is not affected by variations in the detection accuracy of the exhaust sensors themselves, differences in the deterioration state of the exhaust sensors, and the influence of the surrounding temperature environment. Can be accurately determined, and the cost can be reduced by determining using only one exhaust sensor without using two exhaust sensors.
第１〜８図はこの発明の実施例を示し、第１図は内燃機
関の空燃比制御装置の概略構成図、第２図は切換弁部位
の拡大斜視図、第３図は第１バイパス通路を集合バイパ
ス通路に切換連通させた状態の断面説明図、第４図は第
２バイパス通路を集合バイパス通路に切換連通させた状
態の断面説明図、第５図は第１バイパス通路の排気によ
るO2センサの検出信号の出力波形を示す図、第６図は第
２バイパス通路の排気による触媒体が劣化していない場
合のO2センサの検出信号の出力波形を示す図、第７図は
第１バイパス通路の排気によるO2センサの検出信号の出
力波形を示す図、第８図は第２バイパス通路の排気によ
る触媒体が劣化している場合のO2センサの検出信号の出
力波形を示す図である。 第９〜18図は従来例を示し、第９図は上流側排気通路と
下流側排気通路とに第１・第２のO2センサを設けた触媒
体の断面図、第10図は上流側排気通路に設けた第１のO2
センサの検出信号の出力波形図、第11図は触媒体が劣化
していない場合の下流側排気通路に設けた第２のO2セン
サの検出信号の出力波形図、第12図は上流側排気通路に
設けた第１のO2センサの検出信号の出力波形を示す図、
第13図は触媒体が劣化している場合の下流側排気通路に
設けた第２のO2センサの検出信号の出力波形を示す図、
第14図は上流側排気通路に設けた第１のO2センサの検出
信号の応答時間を示す図、第15図は下流側排気通路に設
けた第２のO2センサの検出信号の応答時間を示す図、第
16図は温度センサを設けた触媒体の断面図、第17図は触
媒体温度による劣化状態を判断する温度を示す図、第18
図は内燃機関の空燃比制御装置の概略構成図である。 図において、２は内燃機関、４は吸気マニホルド、６は
吸気通路、８は排気マニホルド、10は排気通路、12は触
媒体、14は第１分岐部、16は第１路バイパス通路、18は
第２分岐部、20は第２路バイパス通路、22は集合部、24
は集合バイパス通路、26は合流部、28は切換弁、30はO2
センサ、42はアクチュエータ、44は制御部、46は水温セ
ンサ、48は圧力センサ、50は回転数センサ、52は車速セ
ンサ、54はダイアグノーシスランプである。1 to 8 show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an air-fuel ratio control device for an internal combustion engine, FIG. 2 is an enlarged perspective view of a switching valve portion, and FIG. 3 is a first bypass passage. FIG. 4 is a cross-sectional explanatory view of a state in which the second bypass passage is switched to the collective bypass passage, and FIG. 5 is a cross-sectional explanatory view of a state in which the second bypass passage is switched to the collective bypass passage. FIG. 6 is a diagram showing an output waveform of a detection signal of the two sensors, FIG. 6 is a diagram showing an output waveform of a detection signal of the O 2 sensor when the catalyst body is not deteriorated by exhaustion of the second bypass passage, and FIG. FIG. 8 is a diagram showing an output waveform of a detection signal of the O 2 sensor due to exhaust gas in the first bypass passage. FIG. 8 shows an output waveform of a detection signal of the O 2 sensor when the catalyst body is deteriorated due to exhaust gas in the second bypass passage. FIG. 9 to 18 show a conventional example, FIG. 9 is a cross-sectional view of a catalyst body provided with first and second O 2 sensors in an upstream exhaust passage and a downstream exhaust passage, and FIG. The first O 2 provided in the exhaust passage
FIG. 11 is an output waveform diagram of a detection signal of the sensor, FIG. 11 is an output waveform diagram of a detection signal of the second O 2 sensor provided in the downstream exhaust passage when the catalyst body is not deteriorated, and FIG. The figure showing the output waveform of the detection signal of the first O 2 sensor provided in the passage,
FIG. 13 is a diagram showing an output waveform of a detection signal of a second O 2 sensor provided in the downstream exhaust passage when the catalyst body is deteriorated,
FIG. 14 is a diagram showing a response time of a detection signal of a first O 2 sensor provided in an upstream exhaust passage, and FIG. 15 is a response time of a detection signal of a second O 2 sensor provided in a downstream exhaust passage. The figure showing the
FIG. 16 is a sectional view of a catalyst body provided with a temperature sensor, FIG. 17 is a diagram showing a temperature for judging a deterioration state due to the catalyst body temperature, and FIG.
The figure is a schematic configuration diagram of an air-fuel ratio control device for an internal combustion engine. In the figure, 2 is an internal combustion engine, 4 is an intake manifold, 6 is an intake passage, 8 is an exhaust manifold, 10 is an exhaust passage, 12 is a catalyst, 14 is a first branch portion, 16 is a first passage bypass passage, and 18 is a first passage bypass passage. The second branch portion, 20 is the second road bypass passage, 22 is the collecting portion, 24
Is the collective bypass passage, 26 is the junction, 28 is the switching valve, 30 is O 2
A sensor, 42 is an actuator, 44 is a control unit, 46 is a water temperature sensor, 48 is a pressure sensor, 50 is a rotation speed sensor, 52 is a vehicle speed sensor, and 54 is a diagnosis lamp.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) F02D 41/14 F02D 41/22 F01N 3/20 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 7 , DB name) F02D 41/14 F02D 41/22 F01N 3/20
Claims (1)
側排気通路の第１分岐部に始端側を連通する第１路バイ
パス通路を設けるとともに前記触媒体の下流側排気通路
の第２分岐部に始端側を連通する第２路バイパス通路を
設け、前記第１バイパス通路及び第２バイパス通路の各
終端側を集合部において集合して集合バイパス通路の始
端側に連通して設け、この集合バイパス通路の終端側を
前記第２分岐部よりも下流側の排気通路の合流部に連通
させて設け、前記第１バイパス通路及び第２バイパス通
路を前記集合バイパス通路に選択的に切換連通させる切
換弁を前記集合部に設けるとともに前記集合バイパス通
路に唯一の排気センサを設け、前記切換弁により前記第
１バイパス通路を前記集合バイパス通路に切換連通させ
た状態における前記排気センサの検出信号により前記内
燃機関の空燃比を目標空燃比に制御するとともに、前記
内燃機関の所定運転状態において前記切換弁により前記
第１バイパス通路を前記集合バイパス通路に切換連通さ
せた状態における前記排気センサの検出信号と前記切換
弁により前記第２バイパス通路を前記集合バイパス通路
に切換連通させた状態における前記排気センサの検出信
号とを比較して前記触媒体の劣化状態を判断する制御手
段を設けたことを特徴とする内燃機関の空燃比制御装
置。A first bypass passage communicating with a start end of a first branch portion of an upstream exhaust passage of a catalyst body provided in an exhaust passage of an internal combustion engine is provided, and a second bypass passage of a downstream exhaust passage of the catalyst body is provided. A second path bypass passage communicating with the start end side of the branch portion is provided, and respective end sides of the first bypass passage and the second bypass passage are gathered at the collecting portion and provided so as to communicate with the starting end side of the collective bypass passage. An end side of the collective bypass passage is provided so as to communicate with a junction of the exhaust passage downstream of the second branch portion, and the first bypass passage and the second bypass passage are selectively switched to the collective bypass passage. A switching valve is provided in the collecting portion and a single exhaust sensor is provided in the collecting bypass passage, and the first bypass passage is switched to the collecting bypass passage by the switching valve. An air-fuel ratio of the internal combustion engine is controlled to a target air-fuel ratio by a detection signal of an exhaust sensor, and in a state where the first bypass passage is switched to the collective bypass passage by the switching valve in a predetermined operation state of the internal combustion engine. Control means for comparing a detection signal of the exhaust sensor with a detection signal of the exhaust sensor in a state where the second bypass passage is switched to the collective bypass passage by the switching valve to determine a deterioration state of the catalyst body; An air-fuel ratio control device for an internal combustion engine, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2078221A JP3006021B2 (en) | 1990-03-27 | 1990-03-27 | Air-fuel ratio control device for internal combustion engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2078221A JP3006021B2 (en) | 1990-03-27 | 1990-03-27 | Air-fuel ratio control device for internal combustion engine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03279645A JPH03279645A (en) | 1991-12-10 |
| JP3006021B2 true JP3006021B2 (en) | 2000-02-07 |
Family
ID=13655997
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2078221A Expired - Lifetime JP3006021B2 (en) | 1990-03-27 | 1990-03-27 | Air-fuel ratio control device for internal combustion engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3006021B2 (en) |
-
1990
- 1990-03-27 JP JP2078221A patent/JP3006021B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03279645A (en) | 1991-12-10 |
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