JP2009221915A - Exhaust emission control device of internal combustion engine - Google Patents
Exhaust emission control device of internal combustion engine Download PDFInfo
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Abstract
Description
本発明は、上流触媒及び下流触媒が排気通路上に直列に配置された内燃機関の排気浄化装置に関する。 The present invention relates to an exhaust purification device for an internal combustion engine in which an upstream catalyst and a downstream catalyst are arranged in series on an exhaust passage.
この種の技術が、例えば特許文献1に記載されている。特許文献1には、下流触媒の前後に排気温センサを設けて、下流触媒前後の排気温の差に基づいて下流触媒でのHC反応量を推定することによって、上流触媒へのHC供給量を制御する技術が提案されている。具体的には、下流触媒でのHC反応量(HC供給量)が不足している場合には、上流からのHC供給量を増量する制御を行っている。こうすることで、上流触媒及び下流触媒に対する過不足のないHCの供給を図っている。 This type of technique is described in Patent Document 1, for example. In Patent Document 1, an exhaust temperature sensor is provided before and after the downstream catalyst, and the amount of HC supplied to the upstream catalyst is estimated by estimating the amount of HC reaction in the downstream catalyst based on the difference in exhaust temperature before and after the downstream catalyst. Control techniques have been proposed. Specifically, when the amount of HC reaction (HC supply amount) in the downstream catalyst is insufficient, control is performed to increase the amount of HC supply from the upstream. By doing so, the supply of HC without excess or deficiency to the upstream catalyst and the downstream catalyst is attempted.
しかしながら、上記した特許文献1に記載された技術では、精度良く制御を行うために、下流触媒前後の排気温を取得するための2つの温度センサを用いる必要があった。そのため、コストアップしてしまう場合があった。 However, in the technique described in Patent Document 1 described above, it is necessary to use two temperature sensors for acquiring exhaust gas temperatures before and after the downstream catalyst in order to perform control with high accuracy. As a result, the cost may increase.
本発明は、上記のような課題を解決するためになされたものであり、1つの温度センサのみを用いて、下流触媒の温度を精度よく推定可能な内燃機関の排気浄化装置を提供することを目的とする。 The present invention has been made to solve the above problems, and provides an exhaust purification device for an internal combustion engine that can accurately estimate the temperature of a downstream catalyst using only one temperature sensor. Objective.
本発明の1つの観点では、排気通路上に設けられた第1の触媒と、前記排気通路上における前記第1の触媒の下流側に設けられた第2の触媒と、を備えた内燃機関の排気浄化装置は、前記第1の触媒からのすり抜けHC量を推定するすり抜けHC量推定手段と、前記すり抜けHC量に基づいてすり抜けHCによる前記第2の触媒の発熱を求め、当該発熱に基づいて前記第2の触媒の温度を推定する第2の触媒温度推定手段と、を備える。 In one aspect of the present invention, an internal combustion engine comprising: a first catalyst provided on an exhaust passage; and a second catalyst provided on the exhaust passage downstream of the first catalyst. The exhaust emission control device obtains a passing-through HC amount estimating means for estimating a slipping-off HC amount from the first catalyst, and calculates heat generation of the second catalyst due to the passing-through HC based on the passing-through HC amount, and based on the generated heat Second catalyst temperature estimating means for estimating the temperature of the second catalyst.
上記の内燃機関の排気浄化装置は、排気通路上に直列に配置された第1の触媒(上流触媒)及び第2の触媒(下流触媒)を用いて、内燃機関から排出された排気ガスを浄化するために好適に利用される。すり抜けHC量推定手段は、第1の触媒からすり抜けたHC量を推定し、第2の触媒温度推定手段は、第1の触媒からすり抜けたHCによる第2の触媒の発熱を考慮して第2の触媒温度を推定する。これにより、第2の触媒における前後の排気温を用いずに(例えば、第2の触媒前後の排気温を取得するための2つの温度センサを用いずに)、第2の触媒の温度を精度良く推定することが可能となる。 The exhaust gas purification apparatus for an internal combustion engine purifies exhaust gas discharged from the internal combustion engine using a first catalyst (upstream catalyst) and a second catalyst (downstream catalyst) arranged in series on the exhaust passage. It is preferably used for this purpose. The slip-through HC amount estimation means estimates the amount of HC slipped from the first catalyst, and the second catalyst temperature estimation means takes into account the second catalyst heat generated by the HC slipping from the first catalyst. Estimate the catalyst temperature. Accordingly, the temperature of the second catalyst is accurately determined without using the exhaust temperatures before and after the second catalyst (for example, without using two temperature sensors for acquiring the exhaust temperatures before and after the second catalyst). It is possible to estimate well.
上記の内燃機関の排気浄化装置の一態様では、前記すり抜けHC量推定手段は、前記第1の触媒への入りガス温度、前記第1の触媒の温度、及び前記第2の触媒の目標温度に基づいて、前記第1の触媒へのHC供給量に対する当該第1の触媒におけるHC反応量の割合を求め、前記割合に基づいて前記すり抜けHC量を推定する。これにより、すり抜けHC量を精度良く推定することができる。 In one aspect of the exhaust gas purification apparatus for an internal combustion engine, the slippage HC amount estimating means is configured to adjust the temperature of the gas entering the first catalyst, the temperature of the first catalyst, and the target temperature of the second catalyst. Based on this, the ratio of the amount of HC reaction in the first catalyst to the amount of HC supplied to the first catalyst is obtained, and the slip-through HC amount is estimated based on the ratio. Thereby, it is possible to accurately estimate the slip-through HC amount.
上記の内燃機関の排気浄化装置において好適には、前記第1の触媒と前記第2の触媒との間を通過する排気ガスの温度を取得する排気ガス温度取得手段を更に備え、前記第2の触媒温度推定手段は、前記すり抜けHCによる前記第2の触媒の発熱を含む前記第2の触媒の発熱量と放熱量との差に対応する温度を、前記排気ガス温度取得手段によって取得された排気ガスの温度に加算することによって、前記第2の触媒の温度を求める。これにより、第1の触媒と第2の触媒との間の排気温のみを取得することで(例えば1つの温度センサのみを用いることで)、第2の触媒の温度を精度良く推定することが可能となる。 Preferably, the exhaust gas purification apparatus for an internal combustion engine further includes exhaust gas temperature acquisition means for acquiring a temperature of exhaust gas passing between the first catalyst and the second catalyst, The catalyst temperature estimating means is an exhaust gas temperature acquired by the exhaust gas temperature acquiring means, corresponding to a difference between the heat value of the second catalyst including the heat generation of the second catalyst due to the slip-through HC and the heat radiation amount. The temperature of the second catalyst is obtained by adding to the temperature of the gas. Thereby, by acquiring only the exhaust temperature between the first catalyst and the second catalyst (for example, by using only one temperature sensor), the temperature of the second catalyst can be accurately estimated. It becomes possible.
以下、図面を参照して本発明の好適な実施の形態について説明する。 Preferred embodiments of the present invention will be described below with reference to the drawings.
[全体構成]
図1は、本実施形態に係る内燃機関の排気浄化装置10の概略構成図を示す。図1では、実線矢印が排気ガスの流れを示し、破線矢印が信号の入出力を示している。
[overall structure]
FIG. 1 is a schematic configuration diagram of an exhaust
内燃機関の排気浄化装置10は、主に、排気通路1と、上流触媒2と、下流触媒3と、排気温センサ4と、ECU(Engine Control Unit)7と、を有する。内燃機関の排気浄化装置10は、車両に搭載され、内燃機関(ガソリンエンジンやディーゼルエンジン)から排出された排気ガスを浄化するために利用される。
An
上流触媒2及び下流触媒3は、排気ガス中のNOxやSOxなどを浄化可能に構成されている。例えば、上流触媒2は酸化触媒などで構成され、下流触媒3はDPR(Diesel Particulate active Reduction system)などで構成される。上流触媒2及び下流触媒3には、上流触媒2の上流側から、NOxの還元剤として燃料等のHC(炭化水素)が供給される。例えば、燃料噴射弁(不図示)や排気通路1上に設けられた燃料添加弁(不図示)より燃料を添加することによって、上流触媒2及び下流触媒3へHCが供給される。なお、上流触媒2、下流触媒3は、それぞれ本発明における第1の触媒、第2の触媒に相当する。 The upstream catalyst 2 and the downstream catalyst 3 are configured to be able to purify NOx, SOx and the like in the exhaust gas. For example, the upstream catalyst 2 is composed of an oxidation catalyst or the like, and the downstream catalyst 3 is composed of a DPR (Diesel Particulate active Reduction system) or the like. The upstream catalyst 2 and the downstream catalyst 3 are supplied with HC (hydrocarbon) such as fuel as a NOx reducing agent from the upstream side of the upstream catalyst 2. For example, HC is supplied to the upstream catalyst 2 and the downstream catalyst 3 by adding fuel from a fuel injection valve (not shown) or a fuel addition valve (not shown) provided on the exhaust passage 1. The upstream catalyst 2 and the downstream catalyst 3 correspond to the first catalyst and the second catalyst in the present invention, respectively.
排気温センサ4は、上流触媒2と下流触媒3との間の排気通路1上に設けられており、排気ガスの温度(排気温)を検出する。当該排気温は、下流触媒3への入りガス温度に相当する。排気温センサ4は、検出した排気温に対応する検出信号をECU7に供給する。なお、排気温センサ4は、本発明における排気ガス温度取得手段に相当する。 The exhaust temperature sensor 4 is provided on the exhaust passage 1 between the upstream catalyst 2 and the downstream catalyst 3, and detects the temperature of exhaust gas (exhaust temperature). The exhaust temperature corresponds to the temperature of the gas entering the downstream catalyst 3. The exhaust temperature sensor 4 supplies a detection signal corresponding to the detected exhaust temperature to the ECU 7. The exhaust temperature sensor 4 corresponds to the exhaust gas temperature acquisition means in the present invention.
ECU7は、図示しないCPU(Central Processing Unit)、ROM(Read Only Memory)及びRAM(Random Access Memory)などを備えて構成される。本実施形態においては、ECU7は、上流触媒2からのすり抜けHC量を推定するすり抜けHC量推定手段、及び下流触媒3の温度を推定する第2の触媒温度推定手段として機能する。なお、ECU7が行う処理の詳細は後述する。 The ECU 7 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). In the present embodiment, the ECU 7 functions as a slip-through HC amount estimation means for estimating the slip-through HC amount from the upstream catalyst 2 and a second catalyst temperature estimation means for estimating the temperature of the downstream catalyst 3. Details of the processing performed by the ECU 7 will be described later.
なお、図1に示すように、以下では、上流触媒2の上流側の排気温(上流触媒2への入りガス温度)を「T1」と表記し、上流触媒2の温度を「Tc1」と表記し、上流触媒2と下流触媒3との間の排気温(排気温センサ4によって検出される温度)を「T2」と表記し、下流触媒3の温度を「Tc2」と表記する。 In the following, as shown in FIG. 1, the exhaust temperature upstream of the upstream catalyst 2 (the temperature of the gas entering the upstream catalyst 2) is expressed as “T1”, and the temperature of the upstream catalyst 2 is expressed as “Tc1”. The exhaust temperature between the upstream catalyst 2 and the downstream catalyst 3 (temperature detected by the exhaust temperature sensor 4) is expressed as “T2”, and the temperature of the downstream catalyst 3 is expressed as “Tc2”.
[下流触媒温度推定方法]
次に、本実施形態における下流触媒3の温度Tc2の推定方法について具体的に説明する。
[Downstream catalyst temperature estimation method]
Next, a method for estimating the temperature Tc2 of the downstream catalyst 3 in the present embodiment will be specifically described.
本実施形態では、ECU7は、上流触媒2からすり抜けたHCによる下流触媒3の発熱を考慮して下流触媒3の温度Tc2を推定する。具体的には、ECU7は、上流触媒2をすり抜けたHC量(下流触媒3へのHC供給量にも相当し、以下では「上流触媒すり抜けHC量」と呼ぶ。)を推定し、当該上流触媒すり抜けHC量に基づいてすり抜けHCによる下流触媒3の発熱を求める。この場合、ECU7は、上流触媒2への入りガス温度T1、上流触媒2の温度Tc1、及び下流触媒3の目標温度に基づいて、上流触媒2へのHC供給量に対する当該上流触媒2におけるHC反応量の割合を求め、当該割合に基づいて上流触媒すり抜けHC量を推定する。そして、ECU7は、すり抜けたHCによる下流触媒3の発熱を含む下流触媒3の発熱量と放熱量との差に対応する温度(以下では、「ΔT」と表記する。)を、排気温センサ4によって検出された排気温T2に加算することによって、下流触媒3の温度Tc2を求める。 In the present embodiment, the ECU 7 estimates the temperature Tc2 of the downstream catalyst 3 in consideration of the heat generation of the downstream catalyst 3 due to the HC slipping from the upstream catalyst 2. Specifically, the ECU 7 estimates the amount of HC that has passed through the upstream catalyst 2 (which also corresponds to the amount of HC supplied to the downstream catalyst 3, hereinafter referred to as “upstream catalyst slipping HC amount”), and the upstream catalyst. The heat generation of the downstream catalyst 3 due to the slip-through HC is obtained based on the slip-through HC amount. In this case, the ECU 7 performs the HC reaction in the upstream catalyst 2 with respect to the amount of HC supplied to the upstream catalyst 2 based on the inlet gas temperature T1 to the upstream catalyst 2, the temperature Tc1 of the upstream catalyst 2, and the target temperature of the downstream catalyst 3. The ratio of the amount is obtained, and the amount of HC passing through the upstream catalyst is estimated based on the ratio. Then, the ECU 7 sets the temperature corresponding to the difference between the heat generation amount of the downstream catalyst 3 including the heat generation of the downstream catalyst 3 due to the passing through HC and the heat release amount (hereinafter referred to as “ΔT”), and the exhaust temperature sensor 4. The temperature Tc2 of the downstream catalyst 3 is obtained by adding to the exhaust gas temperature T2 detected by the above.
このように下流触媒3の温度Tc2を推定する理由は、以下の通りである。排気温センサ4が検出した排気温のみを用いて下流触媒3の温度Tc2を推定した場合、言い換えると下流触媒3の前後の排気温を取得するための2つの温度センサを用いずに排気温センサ4のみを用いて下流触媒3の温度Tc2を推定した場合、推定された温度が実際の下流触媒3の温度からずれてしまう場合がある。こうなるのは、上流触媒2からすり抜けたHCによる下流触媒3の発熱に起因するものと考えられる。つまり、上流触媒2からHCがすり抜けたことにより、下流触媒3での反応HC量が変化したためであると考えられる。 The reason for estimating the temperature Tc2 of the downstream catalyst 3 in this way is as follows. When the temperature Tc2 of the downstream catalyst 3 is estimated using only the exhaust temperature detected by the exhaust temperature sensor 4, in other words, without using the two temperature sensors for acquiring the exhaust temperatures before and after the downstream catalyst 3, the exhaust temperature sensor When the temperature Tc2 of the downstream catalyst 3 is estimated using only 4, the estimated temperature may deviate from the actual temperature of the downstream catalyst 3. This is considered to be caused by the heat generation of the downstream catalyst 3 due to the HC slipping from the upstream catalyst 2. In other words, it is considered that the amount of reaction HC in the downstream catalyst 3 has changed due to the passage of HC from the upstream catalyst 2.
したがって、本実施形態では、上流触媒2からすり抜けたHCによる下流触媒3の発熱を考慮して下流触媒3の温度Tc2を推定する。これにより、1つの排気温センサ4のみを用いて、下流触媒3の温度Tc2を精度良く推定することができる。 Therefore, in the present embodiment, the temperature Tc2 of the downstream catalyst 3 is estimated in consideration of the heat generation of the downstream catalyst 3 due to the HC slipping from the upstream catalyst 2. As a result, the temperature Tc2 of the downstream catalyst 3 can be accurately estimated using only one exhaust temperature sensor 4.
次に、下流触媒3の温度Tc2の推定方法について、より詳細に説明する。 Next, a method for estimating the temperature Tc2 of the downstream catalyst 3 will be described in more detail.
ECU7は、前述した下流触媒3の温度Tc2と排気温センサ4によって検出された排気温T2との温度差ΔT(ΔT=Tc2−T2)を算出し、算出された温度差ΔTから下流触媒3の温度Tc2を推定する。ここで、当該温度差ΔTは、下流触媒3における発熱量(以下、「下流触媒発熱量」と呼ぶ。)と放熱量との差に相当すると言える。したがって、ECU7は、下流触媒発熱量及び放熱量をそれぞれ求めることで、温度差ΔTを算出する。そして、ECU7は、算出された温度差ΔTを排気温センサ4によって検出された排気温T2に加算することで、下流触媒3の温度Tc2を求める。なお、放熱量とは、排気温センサ4の下流で放熱された熱量、詳しくは排気温センサ4と下流触媒3(下流触媒3内も含む)との間で放熱された熱量に相当する。 The ECU 7 calculates a temperature difference ΔT (ΔT = Tc2−T2) between the temperature Tc2 of the downstream catalyst 3 described above and the exhaust temperature T2 detected by the exhaust temperature sensor 4, and the downstream temperature of the downstream catalyst 3 is calculated from the calculated temperature difference ΔT. The temperature Tc2 is estimated. Here, it can be said that the temperature difference ΔT corresponds to a difference between a heat generation amount in the downstream catalyst 3 (hereinafter referred to as “downstream catalyst heat generation amount”) and a heat release amount. Therefore, the ECU 7 calculates the temperature difference ΔT by obtaining the downstream catalyst heat generation amount and the heat release amount, respectively. Then, the ECU 7 calculates the temperature Tc2 of the downstream catalyst 3 by adding the calculated temperature difference ΔT to the exhaust gas temperature T2 detected by the exhaust gas temperature sensor 4. The amount of heat released corresponds to the amount of heat radiated downstream of the exhaust temperature sensor 4, more specifically, the amount of heat radiated between the exhaust temperature sensor 4 and the downstream catalyst 3 (including the inside of the downstream catalyst 3).
具体的には、ECU7は、以下の式(1)から温度差ΔTを算出する。 Specifically, the ECU 7 calculates the temperature difference ΔT from the following equation (1).
次に、式(1)中の上流触媒すり抜けHC量の求め方について、具体的に説明する。ECU7は、上流触媒2へのHC供給量に対する当該上流触媒2におけるHC反応量の割合に基づいて、上流触媒すり抜けHC量を推定する。具体的には、ECU7は、以下の式(2)から上流触媒すり抜けHC量を求める。 Next, how to determine the amount of HC passing through the upstream catalyst in the formula (1) will be specifically described. The ECU 7 estimates the amount of HC passing through the upstream catalyst based on the ratio of the amount of HC reaction in the upstream catalyst 2 to the amount of HC supplied to the upstream catalyst 2. Specifically, the ECU 7 determines the amount of HC passing through the upstream catalyst from the following equation (2).
なお、上流触媒2の入りガス温度T1は、例えば、排気温センサ又は運転状態によって規定されたマップなどから取得される。また、上流触媒2の温度Tc1は、例えば、上流触媒2と下流触媒3との間の排気温T2から推定される。この場合、排気温T2によって規定された上流触媒2の放熱量のマップを予め作成し、当該マップを参照することで上流触媒2の温度Tc1を得ることができる。 The inlet gas temperature T1 of the upstream catalyst 2 is acquired from, for example, an exhaust temperature sensor or a map defined by the operating state. Further, the temperature Tc1 of the upstream catalyst 2 is estimated from the exhaust temperature T2 between the upstream catalyst 2 and the downstream catalyst 3, for example. In this case, the temperature Tc1 of the upstream catalyst 2 can be obtained by preparing a map of the heat release amount of the upstream catalyst 2 defined by the exhaust temperature T2 in advance and referring to the map.
図2は、排気流量と上流触媒2の温度Tc1と排気温T2との関係の一例を示した図である。具体的には、横軸に排気流量を示し、縦軸に上流触媒2の温度Tc1を示している。ECU7は、このような関係を考慮に入れて、排気流量及び排気温T2から、上流触媒2の温度Tc1を推定する。 FIG. 2 is a diagram showing an example of the relationship between the exhaust flow rate, the temperature Tc1 of the upstream catalyst 2, and the exhaust temperature T2. Specifically, the horizontal axis represents the exhaust gas flow rate, and the vertical axis represents the temperature Tc1 of the upstream catalyst 2. The ECU 7 takes the above relationship into consideration and estimates the temperature Tc1 of the upstream catalyst 2 from the exhaust gas flow rate and the exhaust gas temperature T2.
次に、式(1)中の下流触媒浄化率の求め方について、具体的に説明する。ECU7は、排気流量と排気温T2とによって規定されたマップを参照することで、下流触媒浄化率を求める。 Next, how to determine the downstream catalyst purification rate in the formula (1) will be specifically described. The ECU 7 obtains the downstream catalyst purification rate by referring to a map defined by the exhaust gas flow rate and the exhaust gas temperature T2.
図3は、下流触媒浄化率マップの一例を示している。下流触媒浄化率マップは、排気流量(横軸)と排気温T2(縦軸)とによって規定されている。図3に示すように、排気流量が大きくなるほどHCが反応しにくくなり(浄化率が低くなる)、排気流量が小さくなるほどHCが反応しやすくなる(浄化率が高くなる)。また、排気温T2が高くなるほどHCが反応しやすくなり(浄化率が高くなる)、排気温T2が低くなるほどHCが反応しにくくなる(浄化率が低くなる)。ECU7は、排気流量及び排気温T2をセンサより取得し、下流触媒浄化率マップを参照することで、取得された排気流量及び排気温T2に対応する下流触媒浄化率を得る。なお、このようなマップは、予め測定又は解析することで作成される。 FIG. 3 shows an example of the downstream catalyst purification rate map. The downstream catalyst purification rate map is defined by the exhaust flow rate (horizontal axis) and the exhaust temperature T2 (vertical axis). As shown in FIG. 3, as the exhaust gas flow rate increases, HC becomes less likely to react (the purification rate becomes lower), and as the exhaust gas flow rate decreases, HC becomes easier to react (the purification rate becomes higher). Further, the higher the exhaust temperature T2, the easier the reaction of HC (the purification rate becomes higher), and the lower the exhaust temperature T2, the less the reaction of HC (the purification rate becomes lower). The ECU 7 acquires the exhaust flow rate and the exhaust temperature T2 from the sensor, and obtains the downstream catalyst purification rate corresponding to the acquired exhaust flow rate and the exhaust temperature T2 by referring to the downstream catalyst purification rate map. Such a map is created by measuring or analyzing in advance.
次に、式(1)中の放熱量の求め方について、具体的に説明する。ECU7は、排気流量と排気温T2とによって規定されたマップを参照することで、放熱量を求める。 Next, how to calculate the amount of heat release in equation (1) will be described in detail. The ECU 7 obtains the heat release amount by referring to a map defined by the exhaust flow rate and the exhaust temperature T2.
図4は、放熱量のマップ一例を示している。放熱量マップは、排気流量(横軸)と排気温T2(縦軸)とによって規定されている。図4に示すように、排気流量が大きくなるほど放熱しにくくなり(放熱量が小さくなる)、排気流量が小さくなるほど放熱しやすくなる(放熱量が大きくなる)。また、排気温T2が高くなるほど放熱しやすくなり(放熱量が大きくなる)、排気温T2が低くなるほど放熱しにくくなる(放熱量が小さくなる)。ECU7は、排気流量及び排気温T2をセンサより取得し、放熱量マップを参照することで、取得された排気流量及び排気温T2に対応する放熱量を得る。なお、このようなマップは、予め測定又は解析することで作成される。 FIG. 4 shows an example of a map of the heat radiation amount. The heat release map is defined by the exhaust flow rate (horizontal axis) and the exhaust temperature T2 (vertical axis). As shown in FIG. 4, the greater the exhaust flow rate, the more difficult it is to dissipate heat (the amount of heat release decreases), and the smaller the exhaust flow rate, the easier the heat release (the greater the amount of heat dissipation). Further, the higher the exhaust temperature T2, the easier it is to dissipate heat (a greater amount of heat dissipation), and the lower the exhaust temperature T2, the less likely to dissipate heat (the smaller the amount of heat dissipation). The ECU 7 acquires the exhaust flow rate and the exhaust temperature T2 from the sensor, and obtains the heat release amount corresponding to the acquired exhaust flow rate and the exhaust temperature T2 by referring to the heat release amount map. Such a map is created by measuring or analyzing in advance.
以上説明した下流触媒3の温度Tc2の推定方法によれば、1つの排気温センサ4のみを用いて、つまり上流触媒2と下流触媒3との間の排気温のみを取得することで、下流触媒3の温度Tc2を精度良く推定することができる。 According to the estimation method of the temperature Tc2 of the downstream catalyst 3 described above, the downstream catalyst is obtained by using only one exhaust temperature sensor 4, that is, by obtaining only the exhaust temperature between the upstream catalyst 2 and the downstream catalyst 3. 3 can be accurately estimated.
1 排気通路
2 上流触媒(第1の触媒)
3 下流触媒(第2の触媒)
4 排気温センサ
7 ECU
10 内燃機関の排気浄化装置
1 Exhaust passage 2 Upstream catalyst (first catalyst)
3 Downstream catalyst (second catalyst)
4 Exhaust temperature sensor 7 ECU
10 Exhaust gas purification device for internal combustion engine
Claims (3)
前記第1の触媒からのすり抜けHC量を推定するすり抜けHC量推定手段と、
前記すり抜けHC量に基づいてすり抜けHCによる前記第2の触媒の発熱を求め、当該発熱に基づいて前記第2の触媒の温度を推定する第2の触媒温度推定手段と、を備えることを特徴とする内燃機関の排気浄化装置。 An exhaust emission control device for an internal combustion engine, comprising: a first catalyst provided on an exhaust passage; and a second catalyst provided on the exhaust passage downstream of the first catalyst,
Slipping HC amount estimating means for estimating the slipping HC amount from the first catalyst;
And second catalyst temperature estimating means for obtaining heat generation of the second catalyst due to the slip-through HC based on the slip-through HC amount, and estimating the temperature of the second catalyst based on the heat generation. An exhaust purification device for an internal combustion engine.
前記第2の触媒温度推定手段は、前記すり抜けHCによる前記第2の触媒の発熱を含む前記第2の触媒の発熱量と放熱量との差に対応する温度を、前記排気ガス温度取得手段によって取得された排気ガスの温度に加算することによって、前記第2の触媒の温度を求める請求項1又は2に記載の内燃機関の排気浄化装置。 Exhaust gas temperature acquisition means for acquiring the temperature of the exhaust gas passing between the first catalyst and the second catalyst;
The second catalyst temperature estimating means obtains a temperature corresponding to a difference between a heat generation amount and a heat release amount of the second catalyst including heat generation of the second catalyst by the slip-through HC by the exhaust gas temperature acquisition means. The exhaust gas purification apparatus for an internal combustion engine according to claim 1 or 2, wherein the temperature of the second catalyst is obtained by adding to the acquired temperature of the exhaust gas.
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