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Exhaust emission control for engine

A technology of exhaust emission and engine, which is applied in the direction of engine control, electrical control, engine components, etc., and can solve problems such as not included

Inactive Publication Date: 2002-08-14
NISSAN MOTOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the document does not contain any indication that the set air-fuel ratio should be adjusted near the target storage volume

Method used

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  • Exhaust emission control for engine
  • Exhaust emission control for engine
  • Exhaust emission control for engine

Examples

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Effect test

no. 1 example

[0060] The oxygen storage capacity of the three-way catalyst is represented by the following formula:

[0061] Oxygen storage amount = ∑ {exhaust gas amount × (excess / deficiency oxygen concentration upstream of the catalyst - excess / deficiency oxygen concentration downstream of the catalyst)}...(1)

[0062] The excess / deficiency oxygen concentration is defined as follows.

[0063] In the case of stoichiometric oxygen concentration as a reference value with a value of zero, the excess / deficiency ratio of oxygen concentration is expressed by a positive percentage when the oxygen concentration in the exhaust gas is higher than the reference value, and by a negative percentage when it is lower than the reference value Indicates the excess / deficiency ratio of the oxygen concentration. Thus, if Figure 4 As shown, when the air-fuel ratio of the fuel mixture supplied to the engine 1 is rich, that is, when the fuel content of the fuel mixture is higher than that corresponding to the...

no. 2 example

[0193] In this second embodiment, as alluded to above, it is considered that the oxygen storage capacity of the catalyst 10 is divided into high velocity components (quantities) HOSC nand low velocity component (quantity) LOSC n , wherein the high-speed components are stored and released by the noble metals (Pt, Rh, Pd) in the catalyst, and the low-speed components are stored and released by the oxygen storage material in the catalyst 10 . Low Velocity Component LOSC n represents a ratio of high-speed components to HOSC n Oxygen storage and release are large, but the storage / release rate is lower than that of the high-speed component HOSC for the reasons indirectly indicated above n storage / release rate.

[0194] In addition, the high-speed component HOSC n and the low velocity component LOSC n The characteristics simulated are as follows:

[0195] - When storing oxygen, oxygen is preferentially stored as high-speed component HOSC n , only if the high-speed component HO...

no. 3 example

[0277] According to the structure of the exhaust gas purification device of the second embodiment and figure 1 The structure shown is similar, but the program executed by the controller 6 is different. In particular, calculations or estimates of oxygen storage vary. In this second embodiment, the oxygen storage rate in the catalyst 10 is determined in accordance with the ratio of the high-speed component to the low-speed component of the oxygen storage amount. More precisely, whereas in the previous embodiment, the storage rate of the high-speed component is fixed, in the second embodiment, the storage rate of the high-speed component is determined according to the ratio of the high-speed component to the low-speed component.

[0278] refer to Figure 21 The flow chart of is describing the control performed by the controller 6. While maintaining the lambda control state (predetermined air-fuel ratio control condition), the controller 6 implements the lambda control based on...

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Abstract

An engine exhaust emission control arrangement has a catalytic converter including a three-way catalyst. A first oxygen sensor detects an oxygen concentration of exhaust gas upstream of the catalyst and a second oxygen sensor detects an oxygen concentration of exhaust gas downstream of the catalyst. A microprocessor calculates a specific period oxygen storage amount of a catalyst while the upstream oxygen concentration is higher than the stoichiometric concentration and the downstream oxygen concentration is in a predetermined concentration range which has a value approximately equal to the stoichiometric oxygen concentration. The microprocessor also calculates a specific period oxygen release amount of a catalyst while the upstream oxygen concentration is lower than the stoichiometric concentration and the downstream oxygen concentration produces an indication of a predetermined concentration range. A specific period oxygen storage amount is sampled at a time at which the downstream oxygen concentration becomes greater than the predetermined concentration range as a maximum oxygen storage amount and a specific period oxygen release amount is sampled at a time at which the downstream oxygen concentration becomes smaller than the predetermined concentration range as a maximum oxygen release amount. The engine air-fuel ratio is controlled to cause the oxygen storage amount of the catalyst to coincide with a target value which is set at approximately half of an average value of the maximum oxygen storage amount and the maximum oxygen release amount.

Description

technical field [0001] The present invention relates to an engine exhaust gas purification device, which is provided with a catalyst. The present invention particularly relates to a control device of the exhaust gas purification device, which can adjust the air-fuel ratio in the catalytic converter according to the specific oxygen absorption / release characteristics of the catalyst. maintained at stoichiometric levels. Background technique [0002] In order to use a three-way catalyst to remove hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO) from engine exhaust x ), it is important to maintain the gaseous environment of the catalyst so that the oxygen concentration closely corresponds to the stoichiometric air-fuel ratio of the fuel mixture set for the engine. [0003] To achieve this goal, it has been proposed to provide a catalytic converter capable of storing and releasing oxygen in response to the current oxygen concentration in order to maintain the gas...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F02D45/00B01D53/94F01N3/10F01N3/24F01N11/00F02D41/02F02D41/14
CPCB01D2255/908F02D41/1456F02D2200/0814B01D53/9495F01N2900/0422F01N2900/0421B01D53/9454Y02T10/47F01N2550/02F02D41/1441Y02T10/22F01N11/007F02D2200/0816F02D41/14F02D41/0295Y02T10/12Y02T10/40
Inventor 角山雅智柿崎成章松野修
Owner NISSAN MOTOR CO LTD
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