Scr treatment of engine exhaust gases using temperature control
AssigneeJaguar Land Rover Limited
InventorsNeil Bevan, Robert Bending, Michael Davies, Alan Jones
Life of this patent
Estimating the term…
Abstract
The exhaust system of an internal combustion engine is periodically dosed to recharge an SCR catalyst with ammonia. If dosing is scheduled and exhaust gas temperature is too low to ensure recharging, a forced increase in exhaust gas temperature is effected for the period of dosing. A diagnostic to confirm correct operation of a catalytic converter may advantageously run at the same time.
Claims18
1-17. (canceled)
A method of recharging a reducing agent of an SCR catalyst of an exhaust system for an internal combustion engine using a thermally decomposable substance, the method comprising:
- determining that recharging of the SCR catalyst is required;
- determining whether the temperature of exhaust gas in a recharging region of the exhaust system is in a first range or a second range above the first range, wherein in the first range the substance cannot thermally decompose and in the second range the substance can thermally decompose;
- if the temperature of the exhaust gas in the recharging region is in the second range, injecting the thermally decomposable substance into or upstream of the recharging region to recharge the SCR catalyst;
- if the temperature of the exhaust gas in the recharging region is in the first range, raising the temperature of the exhaust gas in the recharging region into the second range;
- and
- injecting the thermally decomposable substance into or upstream of the recharging region to recharge the SCR catalyst.
An exhaust system for connection to an internal combustion engine, the exhaust system comprising:
- an SCR catalyst;
- a recharging region;
- and
- apparatus for dosing urea into said exhaust system upstream of the SCR catalyst, the apparatus being configured to
- determine that recharging the SCR catalyst is desired;
- determine a temperature of exhaust gas in the recharging region of the exhaust system;
- increase the temperature of the exhaust gas in the recharging region if the determined temperature is too low for the urea to decompose to recharge the SCR catalyst;
- and
- inject the urea into or upstream of the recharging region to recharge the SCR catalyst when the temperature of the exhaust gas in the recharging region is hot enough for the urea to decompose to recharge the SCR catalyst.
A motor vehicle comprising:
- an internal combustion engine;
- and
- an exhaust system associated with the engine, the exhaust system comprising:
- an SCR catalyst;
- a recharging region;
- and
- apparatus for dosing urea into said exhaust system upstream of the SCR catalyst, the apparatus being configured to
- determine that recharging the SCR catalyst is desired;
- determine a temperature of exhaust gas in the recharging region of the exhaust system;
- increase the temperature of the exhaust gas in the recharging region if the determined temperature is too low for the urea to decompose to recharge the SCR catalyst;
- and
- inject the urea into or upstream of the recharging region to recharge the SCR catalyst when the temperature of the exhaust gas in the recharging region is hot enough for the urea to decompose to recharge the SCR catalyst.
Dependencies are inferred from the claim text.