SYSTEM AND METHOD FOR TREATING WATER CONDENSATION IN A VEHICLE THERMAL ENGINE EXHAUST LINE

Abstract

Title: SYSTEM AND METHOD FOR TREATING WATER CONDENSATION IN AN EXHAUST LINE OF A VEHICLE THERMAL ENGINE This system (1) comprising a treatment of exhaust gases from a thermal engine (3) of a vehicle, comprises an exhaust line (2) adapted to be coupled to the outlet of said thermal engine (3), a sensor for the composition of said exhaust gas (8), a receptacle (4) coupled to the exhaust line (2) adapted to accumulate a condensed fluid of the exhaust gases (5), comprising heating means (6, 7) adapted to heat said fluid (5) above its evaporation temperature. Figure for the abstract: [Fig 1]

Description

Title of the invention: SYSTEM AND METHOD FOR TREATING WATER CONDENSATION IN A LINE VEHICLE ENGINE EXHAUST Technical field

[0001] The present invention relates to systems for treating the presence of liquid water in the exhaust line of a thermal vehicle due to condensation of water present in the exhaust gases.

[0002] To meet the anti-pollution requirements of internal combustion engine vehicles, the exhaust lines are equipped with pollution control systems which are designed to treat polluting exhaust emissions.

[0003] In particular, when starting the engine, it is essential to reduce the emission of polluting components such as carbon monoxide (CO), nitrogen oxides (NOX), unburned hydrocarbons (HC), fine particles (PM), etc.

[0004] Sensors used to detect some of these polluting molecules and to measure their concentration are installed in the exhaust line. In particular, nitrogen oxide sensors and fine particle sensors are known.

[0005] Also known, more particularly in diesel type engines, are ammonia sensors which are capable of measuring a concentration of ammonia (NH3) at the outlet of a selective nitrogen oxide reduction catalyst installed in the engine exhaust line, supplied with a urea-based solution (Adblue®).

[0006] Oxygen sensors are also known which are installed in an exhaust line and which make it possible to determine the richness of the combustion gases in the exhaust of the engine, by measuring the concentration of oxygen (O2) in the exhaust gases of an engine, in order to adjust the richness of the air-fuel mixture admitted into the engine.

[0007] These different sensors consist of a sensitive ceramic element which is heated, and on which a projection of liquid water can cause cracking or even breakage.

[0008] Thus, it is necessary to initiate their heating when there is no more liquid water at the exhaust line.

[0009] However, an exhaust line often has multiple water retention locations such as low points, siphons, bowls, etc.

[0010] Known systems use the heating of the entire exhaust line beyond the evaporation temperature of the water to eliminate it.

[0011] This heating is obtained for example by the operation of the engine itself in a particular combustion mode in which the combustion efficiency is degraded and heat losses in the exhaust are increased, which causes a delay until the entire exhaust line warms up and the water evaporates, before starting to heat the sensors.

[0012] This delay delays knowledge of the concentration of polluting molecules and / or the exhaust richness in the exhaust line at start-up, which has an impact on the load of polluting gases arriving at the catalytic converter at start-up, and therefore difficulties in achieving the best pollution control performance.

[0013] The aim of the present invention is to prevent liquid water present in the exhaust line from reaching the sensitive element of the sensors, and to accelerate the heating of the sensors by removing water from the exhaust line by evaporation without having to wait for the total heating of the exhaust line by the operation of the engine itself to evacuate this water. Previous techniques

[0014] Document US6290558 discloses a water trap placed at the exhaust of a marine propulsion system. It does not include any dedicated heating means for the evacuation by evaporation of water from the exhaust line.

[0015] Document US6912840 discloses a method for diagnosing a water absorber in the exhaust of a combustion engine.

[0016] The absorber is intended to collect the water emitted from the exhaust in order to keep the engine catalyst dry.

[0017] Heating of the water is carried out by the heat of the engine exhaust gases, but no specific heating means is described.

[0018] Document JP2014126029 describes a water trap in which condensed water is removed from an exhaust line by centrifugal trapping and heated by the heat at the exhaust, without a preferential gravity retention zone or specific heating means. Statement of the invention

[0019] The invention aims to overcome at least some of the aforementioned drawbacks and to propose a system capable of combining the advantages of speed, simplicity and reliability for its implementation in an exhaust line, in particular when starting the engine.

[0020] In view of the above, the subject of the invention is a system for treating exhaust gases from a heat engine of a vehicle, comprising an exhaust line adapted to be coupled to the outlet of said heat engine, a sensor for the composition of said exhaust gas, a receptacle coupled to the exhaust line adapted to accumulate a condensed fluid from the exhaust gases, the system comprising heating means adapted to heat said fluid au- beyond its evaporation temperature.

[0021] Preferably, the fluid comprises water condensed from the exhaust gases.

[0022] For example, the heating means comprise a heating element coupled to an electronic unit configured to be able to activate the heating of the heating element as a function of the presence of fluid in the receptacle and / or an engine start instruction.

[0023] Advantageously, the heating element is an immersion heater comprising a resistive element placed in the receptacle.

[0024] Preferably, the receptacle forms a preferential fluid retention zone which is located at the lowest point of the exhaust line so as to cause the fluid to accumulate by gravity in said zone.

[0025] In one embodiment, the receptacle has an angled shape.

[0026] Advantageously, the receptacle is placed on the exhaust line so as to be positioned between the sensor and a mouth of the exhaust line intended to receive the engine output.

[0027] The system may further provide that the sensor is adapted to detect and measure the concentration of different gaseous components such as, for example, oxygen, nitrogen oxides, fine particles, or even ammonia.

[0028] The invention also relates to a vehicle comprising a system as described above.

[0029] The invention also relates to a method for treating exhaust gases from a heat engine of a vehicle, in an exhaust line at the outlet of a heat engine of a vehicle, comprising the following steps: - providing an engine start instruction, - in a receptacle coupled to the exhaust line in which a fluid resulting from condensation of the exhaust gases is accumulated, heating said fluid beyond its evaporation temperature by first heating means until said fluid evaporates, - then heating a sensor for the composition of said exhaust gas by second heating means coupled to said sensor and separate from the first heating means. Brief description of the drawings

[0030] The invention will be better understood from a detailed study of an embodiment taken as a non-limiting example and illustrated by the appended drawings, in which:

[0031] [Fig-1] represents a system according to the invention.

[0032] [Fig.2] represents the method of implementing the invention at the start of a vehicle. Detailed description

[0033] [Fig.l] illustrates the system 1 for treating exhaust gases from a heat engine 3 of a vehicle of the invention.

[0034] The system 1 can be installed and implemented in a vehicle 1 comprising a thermal engine.

[0035] The system 1 comprises an exhaust line 2 adapted to be coupled to the outlet of said heat engine 3, so that, when the heat engine 3 is used, polluting emissions are produced at the exhaust, the polluting components of which comprise, for example, carbon monoxide, nitrogen oxides, unburned hydrocarbons or fine particles. Furthermore, the exhaust gases comprise dioxygen, and they may comprise ammonia, in particular originating from the decomposition of urea introduced into a catalyst for selective reduction of nitrogen oxides in the engine.

[0036] The system 1 further comprises at least one sensor for the composition of said exhaust gas 8, arranged in the exhaust line 2.

[0037] This sensor 8 is therefore, for example, suitable for detecting gaseous components such as oxygen, nitrogen oxides, fine particles, or ammonia, and for this purpose it may comprise one or more capture heads.

[0038] This sensor 8 is conventionally made up of a sensitive ceramic element which must be heated to operate, and on which a projection of liquid water can cause cracking or even breakage.

[0039] Thus, it is necessary to initiate its heating when there is no more liquid water at the exhaust line 2 to prevent any damage to the sensor 8.

[0040] The system 1 further comprises a receptacle 4 coupled to the exhaust line 2.

[0041] The receptacle 4 is adapted to accumulate a fluid originating from the condensation of the exhaust gas 5.

[0042] Preferably, the fluid 5 comprises water, but it can of course also comprise other traces of components mixed with the water which has condensed and which it is desired to evacuate.

[0043] The multiplication of technical definitions of exhaust lines following increasingly strict anti-pollution standards results in unwanted shapes of the exhaust line 2 and therefore the multiplication of retention zones in the form of bowls at the low points of the exhaust line 2, which are all places of water retention that are difficult to avoid and problematic for the sensor 8, for its reliability and its availability time.

[0044] To solve this problem, the receptacle 4 can form a preferential retention zone for the fluid 2 which is located at the lowest point of the exhaust line 2 of so as to cause the fluid 2 to accumulate by gravity in said zone.

[0045] In one possible embodiment, the receptacle 4 has an angled shape.

[0046] Thus, unlike known exhaust lines which do not have a preferential retention zone and, conversely, have numerous and dispersed retention zones, the receptacle 4 according to the invention makes it possible to concentrate the water from the exhaust line 2 and to simplify the resolution of its evacuation.

[0047] Advantageously, the receptacle 4 is placed on the exhaust line 2 so as to be positioned between the sensor 8 and a mouth of the exhaust line 2 intended to receive the output of the engine 3.

[0048] The system further comprises heating means 6,7 adapted to heat said fluid 5 beyond its evaporation temperature.

[0049] For example, the heating means 6, 7 comprise a heating element coupled to an electronic unit 6 configured to be able to activate the heating of the heating element as a function of the presence of fluid 5 in the receptacle 4 and / or a starting instruction of the engine 3.

[0050] Thus, system 1 can be implemented as a priority when starting engine 3.

[0051] Furthermore, means for detecting water in the receptacle 4 may be provided for even more relevant activation or deactivation of heating means 6.7.

[0052] Advantageously, in particular if the receptacle 4 forms a preferential retention zone for the fluid 2, the heating element is an immersion heater comprising a resistive element placed in the receptacle 4, for example which immerses in the preferential retention zone.

[0053] The system 1 can be implemented in an exhaust line 2 at the outlet of a thermal engine 3 of a vehicle, for the treatment of exhaust gases from said engine 3, by the treatment method comprising the following steps: - a first step El comprising the operation of providing a starting instruction for the motor 3, - a second step E2, in the receptacle 4 coupled to the exhaust line 2 in which the fluid 5 resulting from condensation of the exhaust gases is accumulated, comprising the operation of heating said fluid 5 beyond its evaporation temperature by first heating means 6, 7 until said fluid 5 evaporates, - then a third step E3 comprising the operation of heating the composition sensor of said exhaust gas 8 by second heating means coupled to said sensor 8 and distinct from the first heating means 6, 7.

[0054] Thus, thanks to this method, dedicated heating is provided to the receptacle 4 until the condensed water which has accumulated there, for example, since the last starting the vehicle, to evacuate it from the exhaust line 2 so as to mitigate the risk of this water arriving undesirably on the sensor 8 with the risk of damaging it when the latter heats up to operate shortly after starting the engine 3.

[0055] Furthermore, thanks to this method, we wait until the end of evaporation during step E2 to start heating the sensor 8 for use, which makes it possible to further avoid the sensor 8 in the heated state coming into contact with liquid water.

[0056] Step E1 may comprise, as an alternative or in addition, an operation of verifying the presence of water in the receptacle 4, by a water presence sensor such as a float or an optical detection system.

[0057] This solution offers the possibility of knowing the composition of the exhaust gases earlier following a start of the engine, and therefore of reducing the load of polluting components in the exhaust line 2, and therefore of reducing the dimensioning of a catalyst of the vehicle, in particular its load of noble metals.

[0058] Furthermore, the invention also allows for more flexibility in the location of the gas sensor by allowing positions that are usually avoided because they are located downstream of elements that can retain water.

Claims

Claims

1. Method for treating, in an exhaust line (2) at the outlet of a heat engine (3) of a vehicle, exhaust gases from said engine (3), comprising the following steps: - providing a starting instruction for the engine (3), - in a receptacle (4) coupled to the exhaust line (2) in which a fluid (5) resulting from condensation of the exhaust gases (5) is accumulated, heating said fluid (5) beyond its evaporation temperature by first heating means (6, 7) until said fluid (5) evaporates, - then heating a sensor for the composition of said exhaust gas (8) by second heating means coupled to said sensor (8) and separate from the first heating means (6, 7).

2. System (1) for treating exhaust gases from a heat engine (3) of a vehicle for implementing the method according to claim 1, comprising an exhaust line (2) adapted to be coupled to the outlet of said heat engine (3), a sensor for the composition of said exhaust gas (8), a receptacle (4) coupled to the exhaust line (2) adapted to accumulate a condensed fluid of the exhaust gases (5), characterized in that it comprises heating means (6, 7) adapted to heat said fluid (5) above its evaporation temperature.

3. System (1) according to claim 2, wherein the fluid (5) comprises water condensed from the exhaust gases (5).

4. System (1) according to one of claims 2 and 3, in which the heating means (6, 7) comprise a heating element coupled to an electronic unit (6) configured to be able to activate the heating of the heating element as a function of the presence of fluid (5) in the receptacle (4) and / or a starting instruction of the engine (3).

5. System (1) according to claim 4, wherein the heating element is an immersion heater comprising a resistive element placed in the receptacle (4).

6. System (1) according to any one of claims 2 to 3, in which the receptacle (4) forms a preferential retention zone of the

7.

8.

9.

10. fluid (2) which is located at the lowest point of the exhaust line (2) so as to cause the fluid (2) to accumulate by gravity in said area. System (1) according to any one of claims 2 to 6, in which the receptacle (4) has an angled shape. System (1) according to any one of claims 2 to 7, wherein the receptacle (4) is placed on the exhaust line (2) so as to be positioned between the sensor (8) and a mouth of the exhaust line (2) intended to receive the output of the engine (3). System (1) according to any one of claims 2 to 8, wherein the sensor (8) is adapted to detect gaseous components such as dioxygen, nitrogen oxides, fine particles or ammonia. Vehicle (1) comprising a system (1) according to any one of claims 2 to 9 for implementing the method according to claim 1.

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