ADDITION-AMOUNT CONTROLLER FOR EXHAUST GAS PURIFYING AGENT AND EXHAUST EMISSION CONTROL SYSTEM

• US 20090000278A1
• Filed: 06/26/2008
• Published: 01/01/2009
• Est. Priority Date: 06/27/2007
• Status: Abandoned Application

• Current Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Original Assignee: DENSO Corporation, Nippon Soken, Inc. (DENSO Corporation)
• Inventors: Shimomura, Osamu, Nakamura, Tutomu, Ichikawa, Ataru
• Application Number:
  US12/146,829
• Publication Number:
  US 20090000278A1
• Time in Patent Office: Days
• US Class Current: 60/286
• CPC Class Codes: B01D 2251/2062 Ammonia
• CPC Class Codes: B01D 2258/012 Diesel engines and lean burn gasoline engines
• CPC Class Codes: B01D 53/90 Injecting reactants
• CPC Class Codes: B01D 53/9409 Nitrogen oxides
• CPC Class Codes: B01D 53/9495 Controlling the catalytic process
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2570/18 Ammonia
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/14 Arrangements for the supply of substances, e.g. conduits
• CPC Class Codes: F01N 2610/1406 Storage means for substances, e.g. tanks or reservoirs
• CPC Class Codes: F01N 2610/146 Control thereof, e.g. control of injectors or injection valves
• CPC Class Codes: F01N 2900/08 said parameters being related to the engine
• CPC Class Codes: F01N 2900/1402 Exhaust gas composition
• CPC Class Codes: F01N 2900/1622 Catalyst reducing agent absorption capacity or consumption amount
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

In an addition-amount controller for an exhaust gas purifying agent to be used for an exhaust emission control system of an engine, one mode is executed based on satisfaction of an execution condition for each mode, from among a plurality of control modes. The control modes includes a purification control mode in which an addition amount of NH₃ or an additive serving as a generating source of the NH₃ is determined according to a predetermined parameter associated with an amount of NO_x in the exhaust gas, and a storage control mode in which the addition amount is set to be larger than that in the purification control mode. When a rotation speed of an output shaft of the engine is determined to be decelerated from a higher speed state than an allowable level, the execution condition of the storage control mode is satisfied after a predetermined dissatisfaction time period from start of the deceleration.

Claims

1. An addition-amount controller for an exhaust gas purifying agent, the controller being applied to an exhaust emission control system for purifying exhaust gas emitted from an internal combustion engine, the exhaust emission control system including a catalyst for promoting a specific exhaust gas purification reaction in a temperature range having a critical reaction temperature as a lower limit, and an addition valve for adding an additive of NH₃ (ammonia) or an additive serving as a generating source of the NH₃ to the catalyst itself or the exhaust gas on an upstream side with respect to the catalyst, the additive being adapted to purify NO_x (nitrogen oxides) in the exhaust gas by the exhaust gas purification reaction on the catalyst, the addition-amount controller being adapted to control an amount of addition by the addition valve, the catalyst having properties of storing NH₃ and further decreasing the critical reaction temperature as the amount of NH₃ storage is increased, the addition-amount controller comprising:

mode selection means for selecting one mode to be executed at that time based on satisfaction of an execution condition for each mode, from among a plurality of control modes, the control modes including a purification control mode in which the addition amount by the addition valve is determined according to a predetermined parameter associated with an amount of NO_x in the exhaust gas, and a storage control mode in which the addition amount by the addition valve is set to be larger than that in the purification control mode; and

condition determining means for determining whether a rotation speed of an output shaft of the internal combustion engine is decelerated from a higher speed state than an allowable level,

wherein the execution condition of the storage control mode is set to be satisfied after a predetermined dissatisfaction time period from start of the deceleration when the condition determining means determines that the rotation speed is decelerated from the higher speed state.

5. The addition-amount controller for an exhaust gas purifying agent according to claim 1, further comprising catalyst temperature determination means for determining whether the temperature of the catalyst at that time is lower than an allowable level,

wherein the predetermined dissatisfaction time period has end timing at which the catalyst temperature determination means determines that the temperature of the catalyst is lower than the allowable level.

6. The addition-amount controller for an exhaust gas purifying agent according to claim 5, wherein, when the temperature of the catalyst at that time is in a predetermined temperature range having the critical reaction temperature or a predetermined temperature smaller than the critical reaction temperature as an upper limit boundary value, the catalyst temperature determination means determines that the temperature of the catalyst at that time is lower than the allowable level.

7. The addition-amount controller for an exhaust gas purifying agent, according to claim 1, wherein the execution condition of the purification control mode is set to be satisfied when the execution condition of the storage control mode is not satisfied, and

wherein the mode selection means switches between two types of the control modes of the purification control mode and the storage control mode according to satisfaction or dissatisfaction of the execution condition.

8. The addition-amount controller for an exhaust gas purifying agent, according to claim 1, further comprising:

operating mode determination means for determining whether the operating mode of the internal combustion engine is a preset operating mode in which a load on the output shaft of the internal combustion engine is controlled to be decreased when the catalyst is at a high temperature exceeding the critical reaction temperature; and

prohibition means for prohibiting addition of NH₃ or the additive serving as the generating source of NH₃ by the addition valve to the catalyst in the amount of storing NH₃, during a predetermined time period, when the operating mode determination means determines that the operating mode at that time is the preset operating mode.

10. The addition-amount controller for an exhaust gas purifying agent according to claim 1, wherein the addition valve is adapted to inject and add a urea aqueous solution as the additive to the exhaust gas on an upstream side with respect to the catalyst.

11. An exhaust emission control system comprising:

the addition-amount controller as in claim 10;

the catalyst and the addition valve; and

a urea water supply device for supplying the urea aqueous solution to the addition valve.

2. An addition-amount controller for an exhaust gas purifying agent, the controller being applied to an exhaust emission control system for purifying exhaust gas emitted from an internal combustion engine, the exhaust emission control system including a catalyst for promoting a specific exhaust gas purification reaction in a temperature range having a critical reaction temperature as a lower limit, and an addition valve for adding an additive of NH₃ (ammonia) or an additive serving as a generating source of the NH₃ to the catalyst itself or the exhaust gas on an upstream side with respect to the catalyst, the additive being adapted to purify NO_x (nitrogen oxides) in the exhaust gas by the exhaust gas purification reaction on the catalyst, the addition-amount controller being adapted to control an amount of addition by the addition valve, the catalyst having properties of storing NH₃ and further decreasing the critical reaction temperature as the amount of NH₃ storage is increased, the addition-amount controller comprising:

mode selection means for selecting one mode to be executed at that time based on satisfaction of an execution condition for each mode, from among a plurality of control modes, the control modes including a purification control mode in which the addition amount by the addition valve is determined according to a predetermined parameter associated with an amount of NO_x in the exhaust gas, and a storage control mode in which the addition amount by the addition valve is set to be larger than that in the purification control mode; and

condition determining means for determining whether an amount of fluctuation in a load on the output shaft of the internal combustion engine toward a negative side is larger than an allowable level,

wherein the execution condition of the storage control mode is set to be satisfied after a predetermined dissatisfaction time period from the fluctuation when the condition determining means determines that the amount of fluctuation in the load toward the negative side is larger than the allowable level.

3. An addition-amount controller for an exhaust gas purifying agent, the controller being applied to an exhaust emission control system for purifying exhaust gas emitted from an internal combustion engine, the exhaust emission control system including a catalyst for promoting a specific exhaust gas purification reaction in a temperature range having a critical reaction temperature as a lower limit, and an addition valve for adding an additive of NH₃ (ammonia) or an additive serving as a generating source of the NH₃ to the catalyst itself or the exhaust gas on an upstream side with respect to the catalyst, the additive being adapted to purify NO_x (nitrogen oxides) in the exhaust gas by the exhaust gas purification reaction on the catalyst, the addition-amount controller being adapted to control an amount of addition by the addition valve, the catalyst having properties of storing NH₃ and further decreasing the critical reaction temperature as the amount of NH₃ storage is increased, the addition-amount controller comprising:

mode selection means for selecting one mode to be executed at that time based on satisfaction of an execution condition for each mode, from among a plurality of control modes, the control modes including a purification control mode in which the addition amount by the addition valve is determined according to a predetermined parameter associated with an amount of NO_x in the exhaust gas, and a storage control mode in which the addition amount by the addition valve is set to be larger than that in the purification control mode; and

condition determining means for determining whether an amount of fluctuation in the rotation speed of the output shaft of the internal combustion engine toward the negative side is larger than an allowable level,

wherein the execution condition of the storage control mode is set to be satisfied after a predetermined dissatisfaction time period from the fluctuation when the condition determining means determines that the amount of fluctuation in the rotation speed toward the negative side is larger than the allowable level.

4. An addition-amount controller for an exhaust gas purifying agent, the controller being applied to an exhaust emission control system for purifying exhaust gas emitted from an internal combustion engine, the exhaust emission control system including a catalyst for promoting a specific exhaust gas purification reaction in a temperature range having a critical reaction temperature as a lower limit, and an addition valve for adding an additive of NH₃ (ammonia) or an additive serving as a generating source of the NH₃ to the catalyst itself or the exhaust gas on an upstream side with respect to the catalyst, the additive being adapted to purify NO_x (nitrogen oxides) in the exhaust gas by the exhaust gas purification reaction on the catalyst, the addition-amount controller being adapted to control an amount of addition by the addition valve, the catalyst having properties of storing NH₃ and further decreasing the critical reaction temperature as the amount of NH₃ storage is increased, the addition-amount controller comprising:

mode selection means for selecting one mode to be executed at that time based on satisfaction of an execution condition for each mode, from among a plurality of control modes, the control modes including a purification control mode in which the addition amount by the addition valve is determined according to a predetermined parameter associated with an amount of NO_x in the exhaust gas, and a storage control mode in which the addition amount by the addition valve is set to be larger than that in the purification control mode; and

condition determining means for determining whether fuel cut is performed in the internal combustion engine,

wherein the execution condition of the storage control mode is set to be satisfied after a predetermined dissatisfaction time period from start of the fuel cut when the condition determining means determines that the fuel cut is performed.

9. An addition-amount controller for an exhaust gas purifying agent, the controller being applied to an exhaust emission control system for purifying exhaust gas emitted from an internal combustion engine, the exhaust emission control system including a catalyst for promoting a specific exhaust gas purification reaction in a temperature range having a critical reaction temperature as a lower limit, and an addition valve for adding an additive of NH₃ (ammonia) or an additive serving as a generating source of the NH₃ to the catalyst itself or the exhaust gas on an upstream side with respect to the catalyst, the additive being adapted to purify NO_x (nitrogen oxides) in the exhaust gas by the exhaust gas purification reaction on the catalyst, the addition-amount controller being adapted to control an amount of addition by the addition valve, the catalyst having properties of storing NH₃ and further decreasing the critical reaction temperature as the amount of NH₃ storage is increased, the addition-amount controller comprising:

operating mode determination means for determining whether the operating mode of the internal combustion engine is a preset operating mode in which a load on the output shaft of the internal combustion engine is controlled to be decreased when the catalyst is at a high temperature exceeding the critical reaction temperature; and

prohibition means for prohibiting addition of NH₃ or the additive serving as the generating source of NH₃ by the addition valve to the catalyst in the amount of storing NH₃, only during a predetermined time period, when the operating mode determination means determines that the operating mode at that time is the preset operating mode.