FR3088368A1 - VEHICLE EQUIPPED WITH A SELF-REGENERATING PARTICLE FILTER AND A MOTOR AND METHOD FOR CONTROLLING THE SAME - Google Patents

Abstract

Vehicle comprising an internal combustion engine (2), an exhaust line (4) connected to said engine (2), said line (4) being provided with a particle filter (6), and a supply device d 'piloted air (12) which opens upstream of the filter (6); remarkable in that the filter (6) comprises a filtering medium and a catalytic phase, the catalytic phase having an oxygen storage capacity and an associated control method.

Description

DESCRIPTION

TITLE: VEHICLE EQUIPPED WITH A SELF-REGENERATING PARTICLE FILTER AND AN ENGINE AND ASSOCIATED CONTROL METHOD

Technical area

The invention relates to the field of depollution of heat engines, more particularly to a vehicle provided with an engine connected to a particulate filter and to a method for controlling the latter.

Prior art

The published patent document WO2017 / 085366 discloses a vehicle comprising a heat engine and an exhaust line equipped with a particle filter, connected to the engine. The vehicle also includes an air intake system bypassing the passenger compartment fan which opens upstream of the particulate filter allowing regeneration of the filter by adding oxygen even when the engine is stopped. However, forced fan activation after the engine is stopped can be unpleasant, especially when the fan activation time lasts one or more minutes. In addition, the self-regeneration process of the particulate filter begins at high temperature, around 600 ° C, penalizing the performance of the vehicle on short journeys.

Statement of the invention

The object of the invention is to overcome at least one of the drawbacks of the above-mentioned state of the art. More particularly, the invention aims to significantly reduce the soot emissions of a vehicle fitted with an internal combustion engine.

The subject of the invention is a vehicle comprising an internal combustion engine and an exhaust line connected to the engine, the line being provided with a particle filter, and a piloted air supply device which opens upstream of the filter remarkable in that the filter comprises a filtering medium and a catalytic phase, the catalytic phase having an oxygen storage capacity.

According to an advantageous embodiment of the invention, the catalytic phase comprises a pure or doped cerine oxide with at least one element from the following list: La, Zr, Y, Gd, Pr, Nd and Sm, and / or another element of the following list: Ag and Pd.

According to an advantageous embodiment of the invention, the catalytic phase comprises silver-doped zirconium cerine oxide, in particular of the Ceo, 49Zro, 5i02 type.

According to an advantageous embodiment of the invention, the catalytic phase comprises perovskite of the Lai-xy Ag _x Sr _y B O3 type, B being one of the elements on the list: Fe, Mn, Cu Ti, Co and Ni, l element Sr can be replaced by one of the elements of the list: Ca, Ba and K, x being between 0 and 0.5, and y being between 0 and 0.5.

According to an advantageous embodiment of the invention, the piloted air intake device comprises a bypass of a cabin ventilation circuit with a control valve.

According to an advantageous embodiment of the invention, the piloted air supply device comprises an exhaust air injection device comprising a dedicated air pump, the pump being connected to the exhaust line by the through a conduit.

According to an advantageous embodiment of the invention, the engine is of the spark-ignition type operating at least under stoichiometric conditions, and / or the vehicle comprises a three-way catalyst disposed upstream of the particle filter.

The invention also relates to a method of controlling the vehicle according to the invention, the method comprising an action of opening the air supply device so as to circulate air towards the particle filter when at at least one of the following conditions is met: the engine is stopped, the engine is in a starting phase, an engine stop request is present, the vehicle is driven by an engine / generator and / or the vehicle is deceleration phase with the motor driven.

According to an advantageous embodiment of the invention, the activation of opening of the air supply device is restricted in the case where the temperature of the filter is below a predefined threshold, in particular the predefined threshold being between 300 ° C and 400 ° C.

According to an advantageous embodiment of the invention, the air supply device is actively closed after opening if the duration of activation of the air supply device exceeds a predetermined threshold, in particular the predetermined threshold being equal to or less than 1,2, 5, 10 or 20 seconds.

Preferably, the catalytic phase is at least impregnated directly on the surface of walls of incoming channels of the particle filter, deposited on a filtration membrane of the particle filter and / or constituting the membrane.

Preferably, the filtering medium is based on cordierite, aluminum titanate or silicon carbide.

Preferably, the internal combustion engine is combined with an engine / generator forming a hybrid powertrain.

Preferably, the air intake source is bypassed from the engine intake circuit comprising an electrically assisted compressor or turbocharger.

The measures of the invention are advantageous in that the self-regeneration process of the particulate filter starts at low temperature, around 300 ° C instead of 600 ° C for known solutions. In addition, the materials used in the catalytic phase of the particulate filter to ensure the storage of oxygen are much more economical than those of previous solutions, such as metals of the platinum group.

Brief description of the drawings

Other characteristics and advantages of the present invention will be better understood from the description and the drawings and the graph, among which:

[Fig 1] shows an embodiment of the invention;

[Fig 2] shows an example with an air supply connected to a ventilation circuit;

[Fig 3] shows another example with an air supply with a dedicated air pump;

[Fig 4] shows the results of the oxidizing capacity of the particulate filter as a function of temperature.

detailed description

In FIG. 1, an engine 2 of the spark-ignition type operating at least under stoichiometric conditions is connected to an exhaust line 4. The engine 2 and the line 4 are integrated in a vehicle which is not shown. The exhaust gases from engine 2 are successively purified by passing through a first three-way catalyst 8 mounted upstream of a particle filter 6. Downstream of the exhaust line 4 can be a second catalyst 10. A device air supply 12 opens directly upstream of the filter 6. When the engine 2 is stopped for example, the air introduced diffuses into the filter 6. Part of the oxygen in the air introduced is absorbed / stored in the catalytic phase of the filter 6. Another part of the oxygen of the introduced air can be used as oxidant for the self-regeneration of the filter 6. The supply device 12 can also introduce air upstream of the first three-way catalyst 8.

The vehicle can be configured to trigger an opening action of the air supply device 12 so as to circulate air towards the particle filter 6 when at least one of the following conditions is met: the engine is stopped, engine 2 is in a start phase, a request to stop engine 2 is present, the vehicle is driven by an engine / generator and / or the vehicle is decelerating with engine 2 driven , and that the temperature of the filter 6 is less than a predefined threshold, in particular 400 ° C.

The temperature of the filter 6 can be detected using a model or a measurement. Also, the temperature of the exhaust gases can be used as an alternative to the temperature of the filter 6.

The particle filter 6 comprises a filter medium and a catalytic phase. The filter medium can be based on cordierite, aluminum titanate or silicon carbide. The catalytic phase can be at least impregnated directly on the surface of walls of incoming channels of the filter 6, deposited on a filtration membrane of the particle filter 6 and / or constituting the membrane.

The piloted air intake device 12 can comprise a bypass 14 of a cabin ventilation circuit 18 with a control valve 16 as illustrated in FIG. 2.

In FIG. 3, the piloted air supply device 12 can comprise a dedicated air pump 22, the pump 22 being connected to the exhaust line 4 via a conduit 24. A non-valve shown can be mounted in series on the duct 24 in order to control the air flow and / or ensure the tightness of the exhaust line

4.

The oxygen storage and catalytic oxidation properties are well known to those skilled in the art for pure cerine oxide, doped cerine oxide La, Zr, Y, Gd, Pr, Nd, Sm, en presence or absence of precious metals of type Ag, Pd, and their combinations as well as perovskites of the type Lai-xy Agx Sr _y B Os with x = 0 - 0.5 and y = 0 - 0.5. Sr can be replaced by Ca, Ba, K (alkali and alkaline earth), B being included in the following list: Fe, Mn, Ou, Ti, Co and Ni.

More particularly, tests have been carried out with silver-doped cerine oxide zirconium (2% by mass), called Ag-CZ (Ceo.49Zro.51O2). The silver is deposited on a commercial cerine-zirconia oxide by wet impregnation with Ag nitrate. The catalyst is then dried overnight at study at 100 ° C. and then calcined at 700 ° C. in air for 2 hours. It is named in the remainder of the document Ag-CZ.

To reproduce the situation, 200 mg of Ag-CZ powder were introduced into a conventional U-shaped quartz reactor. The powder is first reduced under H2 for one hour at 500 ° C to simulate an oxidation of the soot which results in to reduce the catalytic material. Then an oxidation at room temperature is carried out in the presence of 1% oxygen under 10 1 / h. The oxygen, consumed by the catalyst to re-oxidize, is measured as a function of time by a mass spectrometer (QMS aspec: Quadrupole Mass Spectrometer, Aspec Technology Inc) and a micro-chromatograph (SRA 2000, SRA INSTRUMENTS®) . Re-oxidation is not carried out in air, since monitoring oxygen consumption in the presence of large quantities (21% 02) is very difficult from an analytical point of view. It is known from the state of the art that the kinetics of re-oxidation increases with the partial pressure of oxygen. Consequently, the operating conditions implemented are more restrictive than those of the intended application.

At room temperature, the filling performance of the material is for 1/21 of the actual O2 content in the ambient air:

[Table 1]

% filling of the material with O2 Filling time in O2 Ag-CZ 86% 3 mins

The measurement of the catalytic activity, for the combustion of soot, with the powder thus prepared and previously oxidized, was carried out, from a mechanical mixture between the Ag-CZ powder and soot, by means of oxidation at programmed temperature. The soot used is Printex® U commercial carbon black. Printex® U soot is used as reference soot in numerous studies on pollution control. The measurement of the catalytic activity of the synthesized catalyst for the oxidation of soot is carried out under the following conditions: the soot and the catalyst are mixed in a 1/60 ratio (by mass) and co-ground in a mortar for 15 minutes in order to to obtain intimate contact between the soot and the catalyst. A mass of 200 mg of this mixture is removed and placed in a conventional U-shaped quartz reactor. The experimental conditions for programmed temperature oxidation are: a flow of 250 ppm of Ch and 10% of LLO in the He at 10 l / h. The reactor is heated from 100 ° C to 680 ° C at a rate of 10 ° C / min. The concentration of products obtained (CO and CO2) from the combustion of soot is measured using a gas phase micro-chromatograph (SRA 3000) and a mass spectrometer (QMS aspec). The soot conversion is calculated from the CO and CO2 concentrations and is expressed as a function of the temperature.

Oxidation performance is provided for materials:

- in new condition (calcined at 700 ° C for 2 hours), referenced 34 in Figure 4;

- in the aged state (4 hours at 980 ° C under N2 and 10% water), referenced 32 in Figure 4.

[Table 2]

% of soot oxidized up to 400 ° C at 250 ppm Cte and 10% H2O Oxidation reaction products Soot alone 0% 100% C0 ₂ New soot + Ag-CZ 20% 100% CO ₂ Soot + Ag-CZ aged 5% 100% C0 ₂

FIG. 4 shows the quantity of CO2 produced as a function of the temperature linked to the oxidation of the soot (no production of CO), with Ag-Cz in the aged state 32 and with Ag- Cz in new condition 34. The peaks recorded before 250 ° C are not to be taken into account, because it is the production of CO2 bound to the carbonate present on the surface of the material. The graph then shows an oxidation of the soot which begins at 250 ° C.

Air injection when the temperature is below 250 ° C, allows the oxygen filter to be charged even if the self-regeneration process, i.e. soot oxidation has not yet started substantially. A limited time injection of air is sufficient to charge the oxygen particulate filter.

Even if these results were obtained with Ag-Cz, the same technical effects are manifested for materials having O2 storage and catalytic oxidation properties. These materials are perovskites, pure cerine oxide, doped cerine oxide La, Zr, Y, Gd, Pr, Nd, Sm, in the presence or absence of precious metals of type Ag, Pd, and their combinations.

Claims (10)

1. Vehicle comprising an internal combustion engine (2) and an exhaust line (4) connected to said engine (2), said line (4) being provided with a particle filter (6), and a device for pilot air supply (12) which opens upstream of the filter (6) characterized in that said filter (6) comprises a filtering medium and a catalytic phase, the catalytic phase having an oxygen storage capacity. 2. Vehicle according to claim 1, the catalytic phase comprises a pure or doped cerine oxide with at least one element from the following list: La, Zr, Y, Gd, Pr, Nd and Sm, and / or another element of the following list: Ag and Pd. 3. Vehicle according to one of claims 1 to 2, characterized in that the catalytic phase comprises zirconium cerine oxide doped with silver, in particular of the CeoxgZro.siOa type. 4. Vehicle according to one of claims 1 to 3, characterized in that the catalytic phase comprises perovskite of the Lai-x- _y Ag _x Sr _y B O3 type, B being one of the elements in the list: Fe, Mn , Cu Ti, Co and Ni, the element Sr can be replaced by one of the elements in the list: Ca, Ba and K, x is between 0 and 0.5, and y is between 0 and 0.5. 5. Vehicle according to one of claims 1 to 4, characterized in that the piloted air supply device comprises a bypass (14) of a cabin ventilation circuit (18) with a control valve ( 16). 6. Vehicle according to one of claims 1 to 5, characterized in that the piloted air supply device (12) comprises an exhaust air injection device comprising an air pump (22) dedicated, said pump being connected to the exhaust line (4) via a conduit (24). 7. Vehicle according to one of claims 1 to 6, characterized in that the engine (2) is of the spark-ignition type operating at least under stoichiometric conditions, and / or the vehicle comprises a three-way catalyst (8) disposed upstream of the particulate filter (6). 8. Method for controlling a vehicle comprising an internal combustion engine (2), an exhaust line (4) connected to said engine (2), the line (4) being provided with a particle filter (6) and a piloted air supply device (12) which opens upstream of said filter (6), characterized in that the vehicle is according to one of claims 1 to 7, and the method comprises an action of opening the air supply device (12) so as to circulate air towards the particle filter (6) when at least one of the following conditions is met: said engine (2) is stopped, said engine is in a starting phase, a request to stop said engine (2) is present, said vehicle is driven by an engine / generator and / or the vehicle is decelerating phase with said engine (2) driven. 9. A method of controlling a vehicle according to claim 8, characterized in that the opening action of the air supply device (12) is restricted in the case where the temperature of said filter (6) is lower than a predefined threshold, in particular the predefined threshold being between 300 ° C and 400 ° C. 10. A method of controlling a vehicle according to claim 8 or 9, characterized in that the air supply device (12) is actively closed after opening if the duration of activation of the air supply device exceeds a predetermined threshold, in particular the predetermined threshold being equal to or less than 1.2, 5, 10 or 20 seconds.