# US 8,784,758 B2 · LNT control method for vehicle

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- Number: US 8,784,758 B2
- Document ID: US8784758B2
- Status: Granted
- Kind: B2
- Application number: 13/863,930
- Filed: 2013-04-16
- Published: 2014-06-19
- Granted: 2014-07-22
- Earliest claimed: 2013-04-16
- Assignees: Hyundai Motor Company
- Applicants: Hyundai Motor Company
- Inventors: Pil Seung Kim
- Web page: https://patentgrep.com/patent/US8784758B2

## CPC

- B01D 53/9495: {Controlling the catalytic process}
- F02D 41/025: {by changing the composition of the exhaust gas, e.g. for exothermic reaction on exhaust gas treating apparatus}
- F02D 41/0275: {the exhaust gas treating apparatus being a NOx trap or adsorbent}
- F02D 41/1454: {the characteristics being an oxygen content or concentration or the air-fuel ratio}
- F02D 41/146: {the characteristics being an NOx content or concentration}
- F02D 2200/0802: Temperature of the exhaust gas treatment apparatus
- Y02T 10/12: Improving ICE efficiencies
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An LNT (Lean NOx Trap) control method for vehicles increases a purification rate of NOx while preventing an increase in the amount of slip of separated NOx at a relatively low LNT temperature. The method includes a recycle necessity determining step that determines whether to recycle NOx of a LNT in accordance with an amount of adsorbed NOx, a LNT temperature determining step that determines whether a temperature of the LNT is below a predetermined reference temperature, a rich performing step that performs a rich mode when the temperature of the LNT is equal to the reference temperature or above and a pre-rich step that ejects fuel in a rich state when the temperature of the LNT is below the reference temperature.

## Claims

### Claim 1

A LNT (Lean NOx Trap) control method for a vehicle, comprising:
a recycle necessity determining step that determines whether to recycle NOx of a LNT in accordance with an amount of adsorbed NOx;
a LNT temperature determining step that determines whether a temperature of the LNT is below a predetermined reference temperature, when it is determined in the recycle necessity determining step that it is necessary to recycle the NOx of the LNT;
a rich performing step that performs a rich mode, when the temperature of the LNT is equal to the reference temperature or above; and
a pre-rich step that ejects fuel in a rich state before the rich performing step is conducted, when the temperature of the LNT is below the reference temperature.

### Claim 2 (depends on 1)

The method of claim 1, further comprising a rich mode separation step that keeps a lean state for a predetermined time period, wherein the rich mode separation step is conducted before the rich performing step and after the pre-rich step.

### Claim 3 (depends on 2)

The method of claim 2, wherein the pre-rich step is set to be maintained for a time period shorter than that of the rich performing step and the rich mode separation step is set to be maintained for a time period until the temperature of the LNT increased by the pre-rich step is reflected to a carrier temperature of the LNT.

### Claim 4 (depends on 1)

The method of claim 1, further comprising a rich mode ending step that determines whether conditions to end the rich mode are satisfied and ends the rich mode when the conditions to end the rich mode are satisfied, wherein the rich mode ending step is conducted after the rich performing step.

### Claim 5 (depends on 4)

The method of claim 4, wherein the conditions to end the rich mode are satisfied when the amount of adsorbed NOx to the LNT becomes zero or when lambda sensor values at front and rear ends of the LNT become substantially the same by performing the rich performing step.

### Claim 6 (depends on 1)

The method of claim 1, wherein the reference temperature is set to a temperature that corresponds to a maximal NOx conversion ratio.