FR3078549A1 - METHOD FOR PROTECTION AGAINST WATER RETENTION OF A POSITIONED ELEMENT IN A MOTOR EXHAUST LINE - Google Patents

Abstract

The invention relates to a method for protecting at least one element (5) for decontamination, measurement or attenuation of noise positioned in an exhaust line of a heat engine, the protection being effected against a retention of water in the interior of said element (5), characterized by a step of locating at least one zone of said at least one element (5) capable of becoming a water retention zone in said at least one element (5) and a step of depositing a resin layer (8) on said at least one zone likely to become a water retention zone in order to at least partially fill said at least one zone.

Description

The present invention relates to a method of protection against water retention in an element positioned in an exhaust line of the engine. heat engine, this element possibly being an element for depolluting a chemical body emitted during the operation of the heat engine, a measurement element such as a sensor or a probe and / or an element for attenuating the noise emitted during operation by the engine.

The protection method makes it possible to limit the retention of water in the element positioned in the exhaust line. The exhaust line can contain several elements protected by a protection method according to the present invention.

On spark ignition or compression ignition engines, it is necessary to have more and more quickly compositions of the exhaust gases at the engine outlet. Such control relies on gas analysis probes such as oxygen probes or nitrogen oxide probes, hereinafter also called NOx probes, to analyze the gases. Based on the signals delivered by these probes, a pollution control supervisor corrects the laws of air and fuel injection to refocus the engine on emissions at best.

One of the problems encountered is that it is necessary to heat these probes to around 800 ° C. to make them operational and that there is a major problem with the fact that these probes do not accept being struck by water when hot. There is a way to estimate the presence of water in the exhaust, this is called the dew point.

On the other hand, there are strong constraints on the fact that one or more elements of the exhaust line can accumulate water in cavities. If the driver has to go up the engine speed quickly, the gas dynamics in the exhaust pipe can displace the accumulated water and break the sensors.

It is known that an exhaust line at the outlet of a heat engine comprises several elements for the selective depollution of a pollutant, including a catalyst and a particulate filter. The pollution control elements present in the exhaust line depend on the type of engine, namely whether, on the one hand, the engine is compression-ignition, in particular a diesel engine or operating on diesel fuel or, on the other hand, the engine is spark ignition, in particular a petrol or mixture fuel engine containing petrol.

For a compression ignition engine, an oxidation catalyst is generally provided, a specific particle filter for this type of engine often designated by the acronym DPF filter and a selective catalytic reduction system with, the if necessary, an ammonia rejection conversion catalyst. For a spark-ignition engine, a three-way catalyst is generally provided, a specific particle filter for this type of engine often referred to by the acronym GPF.

For example, a Selective Catalytic Reduction system, known by the acronym RCS and also known by the acronym SCR, works by injection into the exhaust line of a depollution agent called RCS reducing agent, this agent being advantageously but not limited to urea or a urea derivative, a precursor of ammonia which is used to reduce nitrogen oxides or NOx.

In what follows, the name reduction system or RCS system will be used to qualify a selective catalytic reduction system. The same will apply to nitrogen oxides which can also be designated as NOx.

For the two aforementioned engines, a particulate filter of an exhaust line is used for the retention of soot inside. Other pollution control elements may be present in the exhaust line including, without being limiting, an active nitrogen oxide trap or a passive nitrogen oxide trap, Measuring elements ensuring mainly an optimal functioning of the exhaust line and of the abatement elements mentioned or used for the control of the abatement in the exhaust line can also be present, for example an acoustic silencer, a mixer of reducing agent with the gases of exhaust associated with the catalyst of the selective catalytic reduction system, an oxygen sensor, a soot sensor associated with the particle filter, at least one nitrogen oxide sensor as well as pressure or temperature sensors.

For example, the particle filter which must be monitored for filling with soot in order to regenerate it in good time can be associated with a pressure sensor falling on the one hand, the absolute pressures respectively at the upstream terminals and downstream of the filter and, on the other hand, delivering a pressure differential between the upstream and downstream terminals.

Legislative standards in force or to come in many countries impose to control pollutant emissions including carbon dioxide or CO2, carbon monoxide or CO, hydrocarbons or HC, nitrogen oxides or NOX including nitrogen monoxide or NO and nitrogen dioxide or NO2 and ammonia or NH3. The configurations of the reduction system in the presence of a particulate filter can present problems in terms of water accumulation. This problem relates in particular to the nitrogen oxide detection probe or NOx probe downstream of the reduction system, when present, and of the particle filter, but the present invention is not limited to this sole protection of the NOx probe.

To control the reduction system, it is in fact used a NOx probe downstream of the particle filter to measure the NOx rate towards the outlet of the exhaust line. The NOx probes are based on a technology based on ceramic Zirconium where the migration of oxygen ions O ^2- is measured. This probe must be heated within 800 ° C to allow this migrafon.

The problem is that it makes the probe very sensitive to water. The hot probe does not accept contact with water. This is why, the heating and the operation of the NOx probe are only allowed if the dew point in the exhaust line is crossed, this dew point being considered as an indicator that the water has disappeared from the line. exhaust.

Experience shows that, unfortunately, water is also stored in pollution control elements present in the exhaust line, in particular the reduction system and / or the particle filter and that this water can be released. in the exhaust line even if the dew point has been crossed.

Document US-2016/0215675 describes a device for a gas pollution control element in an exhaust line. According to various embodiments, the element for decontaminating exhaust gases is a diesel oxidation catalyst, a diesel particle filter, a decomposition reactor tube, a selective catalytic reduction device and an injection system. a reducing agent or RCS system.

The device for the pollution control element comprises a ceramic thermal barrier coating applied to a surface of the element. The surface may, for example, be an outer wall of a housing for the pollution control element. Such teaching does not, however, protect the pollution control element against water retention inside.

Therefore, the problem underlying the present invention is to prevent, permanently and in a simple way, water retention in an element present in an exhaust line of a heat engine.

To achieve this objective, there is provided according to the invention a method of protecting at least one element for pollution control, measurement or attenuation of noise positioned in an exhaust line of a heat engine, the protection s 'effecting against water retention in the interior of said element, characterized by a step of locating at least one zone of said at least one element capable of becoming a zone of water retention in said at least one element and a step of depositing a layer of resin on said at least one zone capable of becoming a water retention zone in order to at least partially fill said at least one zone.

The present invention is based on the finding that it is possible that water is stored in an element present in the exhaust line such as a particle filter, a selective catalytic reduction system, a silencer or a catalyst present in a motor vehicle exhaust line, even when a dew point temperature in the line is exceeded. This presence of water can be harmful for a downstream probe or sensor, for example a NOx probe disposed downstream of the water-containing depollution element.

According to the present invention, the areas sensitive to water retention are clogged with resin. This improves critical areas for water retention. Adding a suitable resin does not affect the configuration of the exhaust line, since the resin deposit is inside the element and the volume available in the element, the deposit being reduced to a minimum.

The resin must be compatible with the temperatures reached in the element and must not release gaseous agents which would form pollution.

Advantageously, the location of said at least one zone is done by simulating at least one deposit of water by gravity in said at least one element and by identifying the zone or zones of water retention.

Advantageously, the location of said at least one zone is done by experimentation by leaving water to macerate in said at least one element in a position that said at least one element occupies in an exhaust line in operation and in identifying the water retention zone (s).

Advantageously, the location step comprises a measurement for determining a water level capable of being retained in said at least one zone, the level of the layer of resin corresponding to the level of water.

Advantageously, prior to the step of depositing a layer of resin on said at least one zone, said at least one zone undergoes a graining step increasing a roughness of a surface for depositing resin from said to minus one area.

Advantageously, the resin is an epoxy resin or one containing a metal powder.

The invention also relates to a method of mounting an exhaust line of a heat engine comprising at least one element for pollution control, measurement or attenuation of noise, said at least one element being mounted between two exhaust line conduits, characterized in that said at least one element is protected against water retention therein by such a protection process, the deposition of the resin layer taking place just before mounting said at minus one element in the exhaust line.

Advantageously, the resin is a polymerizable resin, a polymerization of the resin in said at least one element being done by placing the exhaust line comprising said at least one element in an oven at a temperature and for a specific predetermined duration. resin.

The present invention relates to an exhaust line of a heat engine comprising at least one element for pollution control, measurement or attenuation of noise mounted between two conduits of the exhaust line, characterized in that said at at least one pollution control element is protected against water retention inside by such a protection method or in that the exhaust line is mounted in accordance with such an assembly method, said at least one element provided internally and locally of a resin layer being selected from the following elements, taken individually or in combination, on the one hand, for a compression-ignition internal combustion engine: an active or passive nitrogen oxide trap, an oxidation catalyst, a particulate filter for compression ignition engine, an acoustic silencer, a selective catalytic reduction system, a reducing agent mixer with c the exhaust gases associated with the selective catalytic reduction system, an oxygen sensor, an ammonia rejection conversion catalyst, a soot sensor and a nitrogen oxide sensor upstream of the particulate filter and the system reduction or, on the other hand, for a positive-ignition engine: a three-way catalyst, a particle filter for a positive-ignition engine, an acoustic silencer, an oxygen sensor, a soot sensor and an oxide sensor nitrogen.

The presence of a resin layer in an ammonia rejection conversion catalyst is however less relevant when there is no measuring element such as a sensor or a probe downstream of this catalyst. ammonia release conversion.

An exhaust line according to the present invention makes it possible to respond to the problem of accumulation of water in one of the elements for cleaning up the exhaust line, accumulation of water which was not taken into consideration by the 'state of the art which provided only to prohibit the operation of a measuring element such as a NOx probe only when the line temperature was below the dew temperature. The present invention makes it possible to prevent water retention in one or more elements present in the exhaust line.

Advantageously, at least the three-way catalyst or the oxidation catalyst, the particle filter and the acoustic silencer are all provided internally and locally with at least one respective resin layer.

Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows and with regard to the appended drawings given by way of nonlimiting examples and in which:

- Figure 1 is a schematic representation of an embodiment of an exhaust line that can be used in the context of a method for detecting the presence of water in the line according to the present invention, this line being specific for a compression ignition combustion engine,

- Figure 2 is a schematic representation of an embodiment of an exhaust line that can be used in the context of a method for detecting the presence of water in the line according to the present invention, this line being specific for a compression ignition combustion engine,

- Figures 3a, 3b; 4a, 4b and 5a, 5b are schematic representations of a sectional view of a portion of an element present in the exhaust line with identification of the water retention zones without implementation of the method of protection against water retention inside the element according to the present invention in Figures 3a, 4a and 5a and with implementation of the protection method according to the invention in Figures 3, 4 and 5, Figures 3a and 3b being enlarged with respect to FIGS. 4a and 4b.

It should be borne in mind that the figures are given by way of examples and are not limitative of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily at the scale of practical applications. In particular, other exhaust systems arranged differently may also come within the scope of the present invention.

If in Figures 3a, 3b; 4a, 4b and 5a, 5b, there is shown as an element present in the exhaust line a catalyst for Figures 3a, 3b and 4a, 4b and a particle filter for Figures 5a, 5b, it is to be kept 'spirit that the present invention can be applied to any element of pollution control or other present in an exhaust line of a heat engine capable of having a water retention zone inside, for example a silencer, a RCS system catalyst, a nitrogen oxide trap, or a measuring element such as a sensor or probe. Such an element can have several water retention zones, which is shown for a catalyst with different water retention zones in FIGS. 3a and 4a.

In what follows, reference is made to all the figures taken in combination. When reference is made to one or more specific figures, these figures are to be taken in combination with the other figures for the recognition of the designated numerical references.

Referring to Figures 1 and 2, the present invention relates to a method of protection against retention of at in an element 1 to 7, 10 to 12 present in a detection of the presence of water in a line 14 exhaust of a heat engine of a motor vehicle, the water being retained in at least one element 1 to 7, 10 to 12 of pollution present in the exhaust line 14.

In Figure 1, the exhaust line 14 is a line at the outlet of a compression ignition engine and, in Figure 2, the exhaust line 14 is a line at the outlet of a spark ignition engine.

The two lines 14 include a particle filter 1, respectively DPF for diesel particle filter and GPF for gasoline particle filter. The particle filter 1 can have upstream and downstream terminals at which absolute pressures are measured or estimated and a first pressure differential used for estimating the soot charge in the particle filter 1 can be established.

For a particulate filter 1 in good condition, there are two main causes for an increase in the pressure differential across the filter. The first cause is the increase in the soot load inside the filter and the second cause is the presence of a significant amount of water inside the filter, this apart from a serious malfunction of the filter. 1 with particles which can moreover be observed, in particular by the presence of a soot sensor.

The two lines 14 may include a catalyst which is an oxidation catalyst 5 for a line with compression ignition and a three-way catalyst 5 for a line 14 with spark ignition.

In general, the exhaust line 14 may include one or more elements 1 to 7, 10 to 12 auxiliaries, these elements 1 to 7, 10 to 12 auxiliaries being chosen individually or in combination from an active or passive trap with nitrogen oxides 4, an oxidation catalyst 5 or three-way, an acoustic muffler 6, a soot sensor 12. It is also possible to provide an upstream NOx probe 10 disposed towards the engine outlet in addition to the NOx probe downstream 11. This is not limiting. The soot sensor 12 makes it possible to identify whether the particle filter 1 allows soot to pass, in which case it is either too full or inoperative and to remedy this state of affairs as quickly as possible.

In Figure 1, there is shown a catalytic reduction system 2 with a mixer 3 of reducing agent with the exhaust gases associated with the selective catalytic reduction system 2, an oxygen sensor, a conversion catalyst 7 ammonia discharges, a soot sensor and a nitrogen oxide probe 10 upstream of the particulate filter 1 and the reduction system 2.

Line 14 may also include duplicates of the reduction system 2 or of the particle filter 1, for example a particle filter 1 impregnated with a reducing agent. The reducing agent mixer 3 or mixing box makes it possible to mix the ammonia originating from the decomposition of the precursor agent, for example originally in the form of urea with the exhaust gases.

It can be used a trap system with active nitrogen oxides 4 without additive of the LNT or Lean NOx Trap type in the English language. Such a trap system eliminates NOx via a brief passage of one or more richness in the gases leaving the engine. The surplus hydrocarbons react with the stored NOx and neutralize them by transforming them into nitrogen gas.

Another system can also be used in the form of a passive nitrogen oxide trap as a passive nitrogen oxide absorber, a trap which is also known under the name of PNA for Passive NOx Adsorber in Anglo-Saxon language. This system is said to be passive because there is no one or higher wealth transition for its NOx purification.

Such passive or active NOx 4 traps can be used in combination with a reduction system 2. This increases the efficiency of elimination of nitrogen oxides by adsorption of nitrogen oxides at low temperature. and desorption of the oxides once the reduction system 2 catalyst is active. As shown in Figure 1, the reduction system 2 is frequently placed downstream of the NOx trap 4, whether active or passive.

In the context of the present invention any of the elements mentioned can serve as elements 1 to 7, 10 to 12 to be protected. This also applies to small measuring elements 10 to 12 such as sensors or measuring probes, particularly when these elements 10 to 12 can be damaged by the present invention. This also applies to a noise attenuation element such as a silencer 6.

Referring to all the figures, the present invention relates to a method for protecting one or more elements 1 to 7, 10 to 12 of pollution control, measurement or attenuation of noise positioned in a line 14 d heat engine exhaust. The protection of the element or elements 1 to 7, 10 to 12 is carried out to prevent water retention in the interior of said element 1 to 7, 10 to 12.

This accumulation of water has a higher probability of occurring when the engine is stopped overnight rather than when the exhaust line 14 is operated at high temperature. There is indeed a greater probability of water storage in the particulate filter 1 of a line 14 of the exhaust system when the engine is stationary cold than the engine running at high temperature. The present invention aims to protect an element 1 to 7, 10 to 12 present in the exhaust line 14 in all conditions and permanently.

The depollution element 1 to 7, 10 to 12 can be a three-way or oxidation catalyst 5, a catalyst 2 of the RCS system or a mixing box 3, a particle filter 1, a NOx trap. 4, these elements being taken individually or in partial or total combination. The noise attenuating element can be a silencer 6 and the measuring element can be one of the aforementioned sensors 10 to 12.

In a preferred embodiment of the present invention, at least the three-way catalyst 5 for a compression-ignition engine or the oxidation catalyst 5, the particle filter 1 and the acoustic silencer 6 are all provided internally and locally at least one respective resin layer 8.

The protection method comprises a step of locating at least one zone of the element 1 to 7, 10 to 12 or of each element 1 to 7, 10 to 12 capable of becoming a zone of water retention 9a in element 1 to 7, 10 to 12. This localization step is carried out element by element, the element possibly not having been integrated into the exhaust line 14.

The method then comprises a step of depositing a resin layer 8 on the area or areas likely to become a water retention area 9a in order to at least partially fill said at least one area 9a.

Water can indeed be deposited by gravity in one or more portions at the bottom of each element 1 to 7, 10 to 12, for example portions forming bowls and to be retained in this or these portions.

In Figures 3a, 4a, 5a with reference also to Figures 1 and 2, it is shown several elements capable of having one or more water retention zones 9a, for example in Figures 3a and 4a portions of a depollution element that is an oxidation catalyst 5 integrated in an exhaust line for a compression-ignition engine as shown in FIG. 1, each of the portions comprising a different water retention zone 9a. An element 1 to 7, 10 to 12 for pollution control, measurement or attenuation of noise can therefore internally comprise several water retention zones 9a.

Figure 5a shows a particle filter 1 with a water retention zone 9a. These examples are not limiting and areas 9a of water retention may relate to other elements 1 to 7, 10 to 12 of pollution control or other elements 1 to 7, 10 to 12 of measurement such as sensors, the sensors being the elements 1 to 7, 10 to 12 most sensitive to the presence of water.

The first step can take place in several different ways. For example, this first step can be done by simulation, advantageously by computer-aided design processing. Since the water is deposited by gravity, one or more water retention zones 9a can be determined virtually.

Alternatively, the location of the water retention zone (s) 9a can be done by experimentation by leaving water to macerate in the element or each element 1 to 7, 10 to 12. After reduction and evaporation partial water in each element 1 to 7, 10 to 12, if there is stagnant water in one or more zones of the element 1 to 7, 10 to 12, it is that this or these zones are retention zones 9a of water. A location of such an area or such areas can thus be carried out.

The element or each element 1 to 7, 10 to 12 must be placed in the substantially horizontal position which it occupies when this element 1 to 7, 10 to 12 is mounted on an exhaust line 14 itself occupying its mounted operating position, for example under a motor vehicle. The element or each element 1 to 7, 10 to 12 is then placed in its operating position and the experimental retention zones 9a will correspond to the actual water retention zones of the element or each element 1 to 7, 10 to 12.

In Figures 3b, 4b and 5b, a layer of resin 8 has been placed in the area which has been recognized as the water retention area 9a in Figures 3a, 4a and 5a. Advantageously, the level of resin layer 8 can reach the water level 13a previously determined, in FIGS. 3a, 4a and 5a, during the step of locating the retention zones 9a of water to completely fill the retention zone of water 9a, as shown in Figures 3b, 4b and 5b.

Referring more particularly to Figures 3a, 3b; 4a, 4b and 5a, 5b while referring to FIGS. 1 and 2, the location step may include a measurement for determining a water level 13a capable of being retained in said at least one zone 9a, the level 13 of the resin layer 8 corresponding to the water level 13a.

To increase the adhesion of the resin to the or each water retention zone 9a, prior to the step of depositing a layer of resin 8 on the or each zone, the zone can undergo a step of graining increasing roughness of a surface for depositing the resin located in the zone.

The embossing is an operation consisting in making the surface of a body slightly rough for further work, in the present case of a coating with a layer of resin 8. The embossing can, for example, be chemical or by sandblasting. A roughness classification can be defined by a Charmille standard. What is called Charmille grain graining is obtained by sandblasting. The measurement of surface states is preferably done with instruments such as roughness meters.

Without being limiting, the resin may be an epoxy resin or containing a metal powder. What is important is that the hardened resin is thermally resistant to the temperatures prevailing in the exhaust line 14, chemically resistant to the chemical elements 1 to 7, 10 to 12 contained in the exhaust gases and impermeable. The metal powder charged with a resin can be based on bronze, brass, copper, stainless steel or nickel.

The invention also relates to a method for mounting an exhaust line 14 of a heat engine comprising at least one element 1 to 7, 10 to 12 for pollution control, measurement or attenuation of noise. Conventionally, the element or each element 1 to 7, 10 to 12 especially when it is a pollution control element, is mounted between two conduits of the exhaust line 14. Element 1 to 7, 10 to 12 can be mounted in line with line 14 when it is a measuring element 10 to 12 such as a sensor.

According to the invention, at least one of the elements 1 to 7, 10 to 12 is protected against water retention therein by a protection method as previously described. The resin layer 8 is deposited just before the assembly of said at least one element 1 to 7, 10 to 12 in the exhaust line 14, this mainly so as not to be damaged and so that all the elements 1 to 7 , 10 to 12 of the exhaust line 14 with a resin deposit are treated simultaneously, this during a possible hardening treatment of the resin layer 8, preferably by polymerization.

The element 1 to 7, 10 to 12 is frequently a pollution control element, if possible placed as far upstream in the line 14 as may contain water which could damage the probes 11, 12 being more in downstream in the exhaust line 14. Resin deposition for an element 6, 7 located at the end of the exhaust line 14 is less essential.

If a measurement sensor 10 to 12 is likely to retain water, it should also receive a deposit of resin inside it, especially if this measurement sensor is sensitive to water.

When the resin is a polymerizable resin, polymerization of the resin in the or each element 1 to 7, 10 to 12 can be done by placing the exhaust line 14 together with the element or all the elements 1 to 7, 10 to 12 mounted in an oven at a predetermined temperature and duration specific to the resin. The duration and the temperature are known from experience or according to the specifications of the supplier of the resin.

The resin can preferably be deposited in one or more elements 1 to 7, 10 to 14 exhaust lines preferentially intended for cold or humid countries for which water has less tendency to evaporate.

The invention is in no way limited to the embodiments described and illustrated which have been given only by way of examples.

Claims (10)

1. Method for protecting at least one element (1 to 7, 10 to 12) for depolluting, measuring or attenuating noise positioned in an exhaust line (14) of a thermal engine, the protection being effected against water retention in the interior of said element (1 to 7, 10 to 12), characterized by a step of locating at least one zone of said at least one element (1 to 7, 10 to 12) capable of becoming a water retention zone (9a) in said at least one element (1 to 7, 10 to 12) and a step of depositing a layer of resin (8) on said at least one zone capable of becoming a water retention zone (9a) in order to at least partially fill said at least one zone (9a). 2. Method according to claim 1, in which the localization of said at least one zone (9a) is done by simulation of at least one deposit of water by gravity in said at least one element (1 to 7, 10 to 12 ) and by identifying the water retention zone (s) (9a). 3. Method according to claim 1, wherein the location of said at least one zone (9a) is done by experimentation by leaving water to macerate in said at least one element (1 to 7, 10 to 12) in a position that said at least one element (1 to 7, 10 to 12) occupies in an exhaust line (14) in operation and by locating the retention zone or zones (9a) of water. 4. Method according to any one of the preceding claims, in which the locating step comprises a measurement for determining a water level (13a) capable of being retained in said at least one zone (9a), the level (13) of the resin layer (8) corresponding to the water level (13a). 5. Method according to any one of the preceding claims, in which, prior to the step of depositing a resin layer (8) on said at least one zone (9a), said at least one zone (9a) is subjected a graining step increasing a roughness of a surface for depositing the resin of said at least one zone (9a). 6. Method according to any one of the preceding claims, in which the resin is an epoxy resin or containing a metallic powder. 7. Method for mounting an exhaust line (14) of a heat engine comprising at least one element (1 to 7, 10 to 12) for pollution control, measurement or attenuation of noise, said at least one element (1 to 7, 10 to 12) being mounted between two conduits of the exhaust line (14), characterized in that said at least one element (1 to 7, 10 to 12) is protected against retention of water inside by a protection method according to any one of the preceding claims, the deposition of the resin layer (8) being made just before the mounting of said at least one element (1 to 7, 10 to 12) in the exhaust line (14). 8. A mounting method according to the preceding claim, wherein the resin is a polymerizable resin, polymerization of the resin in said at least one element (1 to 7, 10 to 12) being done by placing the line (14) of exhaust comprising said at least one element (1 to 7, 10 to 12) in an oven at a temperature and for a predetermined duration specific to the resin. 9. Exhaust line (14) of a heat engine comprising at least one element (1 to 7, 10 to 12) for pollution control, measurement or attenuation of noise mounted between two conduits of line (14) d exhaust, characterized in that said at least one element (1 to 7, 10 to 12) of pollution control is protected against water retention inside by a protection method according to any one of claims 1 to 6 or in that the exhaust line (14) is mounted in accordance with an assembly method according to any one of claims 7 or 8, said at least one element (1 to 7, 10 to 12), provided internally and locally with '' a resin layer (8), being selected from the following elements (1 to 7, 10 to 12) taken individually or in combination, on the one hand, for a compression-ignition internal combustion engine: an active or passive trap at nitrogen oxides (4), an oxidation catalyst (5), a filter (1) through sheets for compression-ignition engines, an acoustic silencer (6), a selective catalytic reduction system (2), a reducing agent mixer (3) with the exhaust gases associated with the selective catalytic reduction system (2) , an oxygen sensor, an ammonia rejection conversion catalyst (7), a soot sensor (12) and a nitrogen oxide sensor (10) upstream of the particle filter (1) and the reduction (2) or, on the other hand, for a positive-ignition engine: a three-way catalyst (5), a particle filter (1) for a positive-ignition engine, an acoustic silencer (6), a oxygen, a soot sensor (12) and a nitrogen oxide probe (10). 10. Exhaust line (14) according to the preceding claim, in which at least the three-way catalyst (5) or the oxidation catalyst (5), the particle filter (1) and the acoustic silencer (6) are all three provided internally and locally with at least one respective resin layer (8).