WO2015170032A1

WO2015170032A1 - Motor vehicle maintaining the depollution function

Info

Publication number: WO2015170032A1
Application number: PCT/FR2015/051119
Authority: WO
Inventors: Gabriel Crehan; Laura BIGI
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2014-05-06
Filing date: 2015-04-24
Publication date: 2015-11-12
Also published as: FR3020833B1; FR3020833A1

Abstract

The invention relates to a motor vehicle comprising an activation module comprising a body for measuring the quality of the nitrogen-oxide-reducing agent (10), the activation module (9, 10) being designed to switch a module (2) for the absorption of nitrogen oxide operating under lean operation conditions in the passive mode into the active mode in the event of insufficient quality of the nitrogen-oxide-reducing agent.

Description

MOTOR VEHICLE HAVING FUNCTION OF

POLLUTION

The invention relates to pollution control devices for combustion engines of motor vehicles, including diesel vehicles and when the exhaust line comprises a selective reduction module of nitrogen oxides.

[0002] Selective catalytic reduction or SCR devices are known for "Selective Catalyst Reduction" according to the English terminology. LNO absorption devices are also known by passive operation poor mode or LNT for "Lean NOx Trap" according to the English terminology, literally poor trap Nox.

[0003] Diesel engines equipped with a selective catalytic reduction device have the advantage of a fuel economy due to operation in poor conditions which allows optimized fuel consumption. However, the presence of an SCR tank which in practice empties before the pre-programmed maintenance visits, thus forcing the driver to fill the tank itself, may appear as a constraint for a potential customer. But if the tank is not filled regularly, the vehicle may be immobilized by legal obligation. Some drivers tend to avoid this constraint by a trick of filling the reducer tank with a substitute liquid that is more available and cheaper. In some cases the substitute liquid is simply water.

Some laws require the car manufacturers to place a poor quality detection device nitrogen oxide reducer to allow to immobilize the vehicle legally in case of such detection. Such a situation is a failure situation both for the driver and both from the point of view of the protection of the environment.

The object of the invention is to provide a vehicle configured for such a vehicle blocking situation can not take place.

This object is achieved according to the invention with a motor vehicle comprising a selective catalytic reduction module of nitrogen oxide using a nitrogen oxide reducing agent, an oxide absorption module. passive nitrogen in passive mode, and an activation module of the absorption module, characterized in that the activation module comprises a quality measuring member of oxide reducer of nitrogen and the activation module is configured to place the absorption module in active mode in case of insufficient quality of the reducing agent of nitrogen oxide.

Advantageously, the quality measuring member of the nitrogen oxide reducing agent is a refractive index measuring member of the nitrogen oxide reducing agent.

Advantageously, the quality measuring member of the nitrogen oxide reducing agent is an electrical conductivity measuring member in the nitrogen oxide reducing agent.

Advantageously, the vehicle comprises a nitrogen oxide reducing agent reservoir and the quality measuring member of the reducing agent is placed in the nitrogen oxide reducing agent reservoir.

Advantageously, the vehicle comprises an exhaust line and the quality measuring member of the nitrogen oxide reducing agent is a nitrogen oxide detector disposed on the exhaust line.

[001 1] Advantageously, the activation module is configured to place the selective catalytic reduction module in passive mode in case of insufficient quality detection of the nitrogen oxide reducing agent.

Advantageously, the vehicle comprises a driver alerting device in case of insufficient quality detection of the nitrogen oxide reducing agent.

Advantageously, the vehicle comprises a dashboard and the alert member is disposed on the dashboard.

Advantageously, the vehicle comprises an exhaust line, the selective catalytic reduction module and the absorption module being constituted by the same unit mounted unitarily on the exhaust line.

Advantageously, the activation module is configured to control an activation of the selective catalytic reduction module after a deactivation of the selective catalytic reduction module, the activation of the selective catalytic reduction module being carried out by the module. activation in response to detection of sufficient quality of nitrogen oxide reducing agent.

Other features, objects and advantages of the invention will appear on reading the detailed description which follows, with reference to the attached figure which shows a combustion engine exhaust line according to one embodiment. of the invention, In the attached figure, there is shown an exhaust line extending from a motor block referenced 1. The exhaust line comprises successively a low-operating NOx trap 2, a selective catalytic reduction catalyst or SCR 3, and a soot-type particle filter 4 or "Soot" according to the English terminology, with or without a coating of SCR type. The exhaust line also comprises a reducing agent injector 5 including a temperature probe, a nitrogen oxide detector 6 disposed between the selective catalytic reduction catalyst 3 and the particulate filter 4, which detector 6 includes a thermocouple, and another nitrogen oxide detector 7, also including a thermocouple, disposed between the engine block 1 and the nitrogen oxide trap 2. A urea reservoir 8 supplies the injection device 5. The The exhaust line is driven by an on-board computer represented under the reference 9, which is for example constituted by the on-board diagnostic device or OBD for "On Board Diagnostics" according to the English terminology. The exhaust line further comprises here a detector of low quality nitrogen oxide reducer, which detector is referenced 10.

The low quality sensor gear 10 is constituted by a probe immersed in the tank 8 and measuring a refractive index in the tank. The computer 9 receives the measurement of the refractive index, which has a different value depending on whether the reservoir contains aqueous urea at the concentration necessary for the proper functioning of the device or water or urea too strongly diluted . Alternatively, the low quality sensor of the reducer may be a spectrometer or a density sensor. Alternatively, the low quality gearhead sensor 10 is a sensor measuring the conductivity in the tank, also indicative of the quality of the nitrogen oxide reducer. According to another variant, the low quality gear reducer detector is simply constituted by a nitrogen oxide detector disposed downstream of the selective reduction module 3, such as the detector 6 in the figure. Such a detector indicates to the computer 9 a high nitrogen oxide content and the computer, considering that the SCR mode is active, deduces that the depollution effect is not obtained and hence deduces the poor quality of the reducer nitrogen oxide.

In active NOx 2 trap mode, the engine operates with an increased diesel fuel consumption of the order of 1 to 2% compared to catalytic reduction operation. However, the driver no longer has to continuously fill the nitrogen oxide reducer tank 8. The LNT module absorbs nitrogen oxides at low temperatures. Preferably, the LNT module comprises low temperature nitrogen oxide storage sites which are designed to release the nitrogen oxides from 200 ° C., so that the nitrogen oxides thus released are treated by the NH ₃ pre-stored in the SCR module, so that the SCR module processes these nitrogen oxides, whether active or not. Activation of the LNT mode, or transition to active LNT mode, can be defined by the presence of fuel-rich phases, with a lambda parameter value of less than 1. In active LNT mode, entrapped nitrogen oxides are transformed in situ with HC due to the rich operating phase. When the LNT mode is not activated, then the LNT module behaves as a lean operating passive nitrogen oxide storage catalyst. The active SCR mode is commonly understood as injecting the nitrogen oxide reducer into the SCR module.

The present embodiment therefore uses two denitrification devices which each operate alternately in active mode or in passive mode. One device is in active mode while the other is in passive mode. For example, the LNT module 2 stores the nitrogen oxide NOx but there is no rich phase to neutralize the stored NOx. The LNT module is then in passive mode because it does not carry out an active NOx depollution. In parallel, the active SCR mode ensures that urea, here Adblue - registered trademark - is injected into the exhaust line to destroy the NOx in the SCR catalyst on the same exhaust line.

When the low quality detector of nitrogen oxide reducer 10 indicates a low quality of the reducer, ie a reducing quality below a predetermined threshold, such as a threshold concentration of urea, then the computer 9 controls a transition from the passive mode to the active mode of the LNT module 2. In the present embodiment, the computer 9 compares the quality of the reducing agent measured by the detector 10 with a pre-recorded quality threshold, and deduces therefrom insufficient quality of the depollution function if the measured quality is below the pre-recorded quality threshold. At the same time, it commands a transition from active mode to passive mode of the SCR module 3. The computer 9 and the poor quality detector 10 of the reducing agent thus constitute an activation module of the LNT mode in the event of detection of poor quality. reducing agent.

In this way, the low quality fluid present in the tank is no longer injected into the exhaust line, but the pollution control function is maintained. The vehicle is therefore no longer likely to be immobilized for reasons of lack of depolluting function. According to an advantageous embodiment, the vehicle comprises a warning means of the driver in case of detection of the low quality of the nitrogen oxide reducer. The driver then becomes aware of the operation with higher fuel consumption and is thus encouraged to go to a garage. Such alerting means is for example a light symbol on the dashboard meaning or that the reducing agent is defective, or that the fuel consumption is degraded.

Once a normal quality reducing agent introduced into the tank, the clearance capacity of the exhaust line returns to normal, and the computer 9 pilot a return to SCR mode. In one variant, the return to SCR mode is controlled by garage specialized tools.

In the present embodiment, the engine is equipped with a single exhaust line which is provided with two separate modules 2 and 3 respectively lean nitrogen oxide absorption and selective catalytic reduction. These modules may be placed upstream or downstream of the particulate filter 4. In a variant, the absorption module and the reduction module may consist of the same member which is mounted unitarily on the exhaust line.

The particulate filter 4 may be impregnated with nitrogen oxide reducer, and be equipped with or without a catalytic coating. Similarly, a soot regeneration additive can be used. The module placed closest to the engine block 1, here the absorption module 2, may contain precious metals for the CO and HC removal function and for the storage function of the nitrogen oxides and denitrification.

The two functions LNT or PNA - Passive NOx Adsorber in the English terminology Absorber NOx passive - and SCR can advantageously coexist in the same catalytic coating because the catalytic formulations become active only under respectively adequate engine operating conditions. Similarly an exhaust gas recirculation system or EGR for "Exhaust Gas Recirculation" in English terminology can be adopted. Such a recirculation system can be at high pressure or at low pressure and it can implement recirculation from a single cylinder or from several cylinders of the engine. Any type of nitrogen oxide reducing agent can be used. The reduction formulation of the selective reduction module may be supported by a conventional wall flow monolith or an exhaust gas flow therethrough of the particulate filter type. The tank 8 may be made of metal or polymer material. It may contain a liquid, gaseous reducing agent or, for example, an absorbed ammonia gas. Any reducing agent may be used to be introduced into the exhaust line. Typical examples are CO, HC, alcohols, glycols, glycerols, esters, acids, ammonia, ammonium, hydroxide, urea, guanidine, guanidium salts, and the like.

It is understood, throughout the present application, as a reducing agent a directly reducing agent (ammonia) or an ammonia precursor; as liquid phase urea, which is intended to turn into ammonia reducing agent when it is injected into the exhaust line.

The invention finds a particularly advantageous application for hybrid vehicles with diesel and electric drive.

Claims

A motor vehicle comprising a selective catalytic reduction module of nitrogen oxide (3) using a nitrogen oxide reducing agent, a passive-mode nitrogen oxide absorption module in passive mode (2). ), and an activation module of the absorption module (9, 10), characterized in that the activation module (9, 10) comprises a quality measuring member of a nitrogen oxide reducer (10). and the activation module (9, 10) is configured to place the absorption module (2) in the active mode in case of insufficient quality of the nitrogen oxide reducing agent.

A motor vehicle according to claim 1, characterized in that the quality measuring member of the nitrogen oxide reducing agent (10) is a refractive index measuring member of the reducing agent of said reducing agent. nitrogen oxide.

A motor vehicle according to claim 1, characterized in that the quality measuring member of the nitrogen oxide reducing agent (10) is an electrical conductivity measuring member in the oxide reducing agent. nitrogen.

4. Motor vehicle according to claim 2 or claim 3, characterized in that it comprises a nitrogen oxide reducing agent reservoir (8) and the quality measuring member of the reducing agent (10). ) is placed in the nitrogen oxide reducing agent reservoir (8).

5. Motor vehicle according to claim 1, characterized in that it comprises an exhaust line and the quality measuring member of the nitrogen oxide reducing agent.

(6, 10) is a nitrogen oxide detector (6) disposed on the exhaust line.

6. Motor vehicle according to any one of the preceding claims, characterized in that the activation module (9,10) is configured to place the selective catalytic reduction module (3) in passive mode in case of detection of insufficient quality of the nitrogen oxide reducing agent.

7. Motor vehicle according to any one of the preceding claims, characterized in that it comprises a driver alerting device in case of insufficient quality detection of the reducing agent of nitrogen oxide.

8. Motor vehicle according to the preceding claim, characterized in that the vehicle comprises an instrument panel and the alert member is disposed on the dashboard.

9. Motor vehicle according to any one of the preceding claims, characterized in that it comprises an exhaust line, the selective catalytic reduction module (3) and the absorption module (2) being constituted by the same organ mounted unitarily on the exhaust line.

10. Motor vehicle according to any one of the preceding claims, characterized in that the activation module (9,10) is configured to control an activation of the selective catalytic reduction module (3) after deactivation of the module. selective catalytic reduction (3), the activation of the selective catalytic reduction module being carried out by the activation module (9,10) in response to detection of sufficient quality of nitrogen oxide reducing agent.