EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE

• US 20170204763A1
• Filed: 05/22/2015
• Published: 07/20/2017
• Est. Priority Date: 05/26/2014
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Nishioka, Hiromasa, Ito, Kazuhiro, Imai, Daichi, Tsukamoto, Yoshihisa, Otsuki, Hiroshi, Notake, Yasumasa
• Granted Patent: US 10,138,778 B2
• Time in Patent Office: Days
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 2570/18 Ammonia
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2900/08 said parameters being related to the engine
• CPC Class Codes: F01N 2900/1616 NH3-slip from catalyst
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 9/002 of filter regeneration, e.g. detection of clogging
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An exhaust purification system including a particulate filter , a selective reduction catalyst provided at a downstream side from the filter, an ammonia ingredient feed device which feeds an ammonia ingredient to the selective reduction catalyst, a control device which controls the amount of the ammonia ingredient which is adsorbed at the selective reduction catalyst to become a target adsorption amount, and a filter regeneration system which performs filter regeneration processing to remove PM which has built up on the particulate filter when an execution start condition stands. When removal of PM is demanded, so long as the execution start condition of the filter regeneration processing by the filter regeneration system does not stand, the target adsorption amount is decreased a plurality of times in stages, and the execution start condition of the filter regeneration processing is changed to a different condition at each stage of the target adsorption amount.

Claims

1. An exhaust purification system of an internal combustion engine, comprising:

a particulate filter which is provided in an engine exhaust passage;

a selective reduction catalyst which is provided in the engine exhaust passage at a downstream side from said particulate filter in a direction of exhaust flow;

an ammonia ingredient feed device which feeds an ammonia ingredient to said selective reduction catalyst;

a control device which controls the amount of feed of ammonia ingredient from said ammonia ingredient feed device so that the amount of the ammonia ingredient which is adsorbed at said selective reduction catalyst becomes a target adsorption amount; and

a filter regeneration system which performs filter regeneration processing to remove PM which has built up on said particulate filter, when an execution start condition of the filter regeneration processing stands,

wherein when removal of PM which has built up on said particulate filter is demanded, so long as the execution start condition of the filter regeneration processing by said filter regeneration system does not stand, said target adsorption amount is decreased a plurality of times in stages, and

said execution start condition of the filter regeneration processing is changed to a different condition at each stage of said target adsorption amount.

2. The exhaust purification system of an internal combustion engine according to claim 1, wherein the execution start condition of the filter regeneration processing is set to a condition with a higher frequency of standing as said target adsorption amount is decreased in stages.

3. The exhaust purification system of an internal combustion engine according to claim 2, wherein each execution start condition of said filter regeneration processing stands when the engine speed is a respective predetermined speed or less;

and

wherein said predetermined speed is set to a higher speed as said target adsorption amount is decreased in stages.

4. The exhaust purification system of an internal combustion engine according to claim 1, wherein said target adsorption amount is again decreased if a cumulative value of amount of discharge of NO_x reaches a predetermined amount after said target adsorption amount is decreased a previous time.

5. The exhaust purification system of an internal combustion engine according to claim 1, wherein said filter regeneration system has a plurality of filter regenerating means for removing PM which has built up on said particulate filter;

and

wherein at each stage of said target adsorption amount, when said execution start condition of the filter regeneration processing stands, a filter regenerating means which partially differs for each stage of said target adsorption amount is used to remove PM which has built up on said particulate filter.

6. The exhaust purification system of an internal combustion engine according to claim 1, wherein

said filter regeneration system has a plurality of filter regenerating means for removing PM which has built up on said particulate filter;

when removal of PM which has built up on said particulate filter is demanded, so long as the execution start condition of the filter regeneration processing by said filter regeneration system does not stand, as a first stage, said target adsorption amount is set to a first adsorption amount and as a second stage, said target adsorption amount is set to a second adsorption amount smaller than said first adsorption amount;

when said target adsorption amount is set to said first adsorption amount, said execution start condition of the filter regeneration processing is set to a first condition, and when said target adsorption amount is set to said first adsorption amount and said execution start condition of the filter regeneration processing stands, PM which has built up on said particulate filter is removed by a first filter regenerating means; and

when said target adsorption amount is set to said second adsorption amount, said execution start condition of the filter regeneration processing is set to a second condition with a higher frequency of standing than said first condition, and when said target adsorption amount is set to said second adsorption amount and said execution start condition of the filter regeneration processing stands, said particulate filter is risen in temperature by a second filter regenerating means which is at least partially different from said first filter regenerating means.

7. The exhaust purification system of an internal combustion engine according to claim 6, wherein

at the time of normal operation when removal of PM which has built up on said particulate filter is not demanded, said target adsorption amount is set to a normal target adsorption amount which is set based on an operation parameter of the internal combustion engine;

when removal of PM which has built up on said particulate filter is demanded, if said first adsorption amount is larger than said normal target adsorption amount, at said first stage, said target adsorption amount is set to said normal target adsorption amount instead of said first adsorption amount; and

when removal of PM which has built up on said particulate filter is demanded, if said second adsorption amount is greater than said normal target adsorption amount, at said second stage, said target adsorption amount is set to said normal target adsorption amount instead of said second adsorption amount.

8. The exhaust purification system of an internal combustion engine according to claim 6, further comprising:

a heater which heats said particulate filter by electric power;

a secondary air feed device which feeds secondary air to said particulate filter; and

a fuel addition valve which feeds fuel to said particulate filter,

wherein said first condition stands when the engine speed becomes zero;

said first filter regenerating means makes the particulate filter rise in temperature by said heater and feeds secondary air from said secondary air feed device when removing PM which has built up on said particulate filter; and

said second filter regenerating means feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter.

9. The exhaust purification system of an internal combustion engine according to claim 6, further comprising:

a heater which heats said particulate filter by electric power; and

a fuel addition valve which feeds fuel to said particulate filter,

wherein said first condition stands when the engine speed is equal to or less than a predetermined idling upper limit speed, which is higher than zero;

said first filter regenerating means makes the particulate filter rise in temperature by said heater and feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter; and

said second filter regenerating means does not use said heater to make the particulate filter rise in temperature but feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter.

10. The exhaust purification system of an internal combustion engine according to claim 6, further comprising:

a heater which heats said particulate filter by electric power;

a secondary air feed device which feeds secondary air to said particulate filter; and

a fuel addition valve which feeds fuel to said particulate filter,

wherein said first condition stands when the engine speed becomes zero, while said second condition stands when the engine speed is equal to or less than a predetermined idling upper limit speed, which is higher than zero,

said first filter regenerating means makes the particulate filter rise in temperature by the heater and feeds secondary air from said secondary air feed device when removing PM which has built up on said particulate filter, and

said second filter regenerating means makes the particulate filter rise in temperature by said heater and feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter.

11. The exhaust purification system of an internal combustion engine according to claim 6 wherein

when removal of PM which has built up on said particulate filter is demanded, so long as the filter regeneration processing by said filter regeneration system is not started, as a third stage, said target adsorption amount is set to a third adsorption amount which is smaller than said second adsorption amount;

and

when said target adsorption amount is set to said third adsorption amount, said execution start condition of the filter regeneration processing is set to a third condition with a higher frequency of standing than said second condition, and when said target adsorption amount is set to said third adsorption amount and said execution start condition of the filter regeneration processing stands, PM which has built up on said particulate filter is removed by a third filter regenerating means which is at least partially different from said first filter regenerating means and said second filter regenerating means.

12. The exhaust purification system of an internal combustion engine according to claim 11, further comprising:

a heater which heats said particulate filter by electric power;

a secondary air feed device which feeds secondary air to said particulate filter, and a fuel addition valve which feeds fuel to said particulate filter,

wherein said first condition stands when the engine speed becomes zero while said second condition stands when the engine speed is equal to or less than a predetermined idling upper limit speed, which is higher than zero;

said first filter regenerating means makes the particulate filter rise in temperature by said heater and feeds secondary air from said secondary air feed device when removing PM which has built up on said particulate filter;

said second filter regenerating means makes the particulate filter rise in temperature by said heater and feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter; and

said third filter regenerating means does not use said heater to raise the temperature of the particulate filter but feeds fuel from said fuel addition valve to said particulate filter when removing PM which has built up on said particulate filter.