FR3054599A1 - SELECTIVE CATALYTIC REDUCING TYPE EXHAUST GAS POST-PROCESSING SYSTEM EQUIPPED WITH A REACTIVE QUALITY SENSOR AS COMPLETE - Google Patents

Abstract

The system according to the invention (1) comprises a control unit (31), a reactive mixing tank (2) and a multiplexed digital link (10). The reaction mixture tank is equipped with a tank management circuit (9) to which a plurality of sensors (80, 81) and a plurality of actuators (4, 5, 6, 7) are connected. The tank management circuit is in communication with the control unit through the multiplexed link. According to the invention, the plurality of sensors comprises a reagent quality sensor (82) which delivers information (RQ) on the quality of the reagent mixture contained in the reservoir, this quality information of the reaction mixture being transmitted to the control unit through the multiplexed link.

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

SELECTIVE CATALYTIC REDUCTION TYPE EXHAUST GAS AFTER-TREATMENT SYSTEM, EQUIPPED WITH REAGENT QUALITY SENSOR AS DURATION.

FR 3 054 599 - A1 (57) The system according to the invention (1) comprises a control unit (31), a reagent mixture tank (2) and a digital multiplexed link (10). The reagent mixing tank is equipped with a tank management circuit (9) to which are connected a plurality of sensors (80, 81) and a plurality of actuators (4,5, 6, 7). The tank management circuit is in communication with the control unit through the multiplexed link. According to the invention, the plurality of sensors includes a reagent quality sensor (82) which delivers information (RQ) on the quality of the reactive mixture contained in the reservoir, this quality information of the reactive mixture being transmitted to the control unit through the multiplexed link.

AT

SELECTIVE CATALYTIC REDUCTION TYPE EXHAUST GAS AFTER-TREATMENT SYSTEM EQUIPPED WITH A REAGENT QUALITY SENSOR SUCH AS UREA [001] The invention relates generally to the automotive field. More particularly, the invention relates to an exhaust gas aftertreatment system of the selective catalytic reduction type and equipped with a reagent quality sensor. This type of system finds particular application in motor vehicles equipped with a diesel type thermal engine.

[002] In motor vehicles, exhaust gas aftertreatment systems have become essential today to meet increasingly stringent environmental standards. Controlling the emissions of nitrogen oxides, generally referred to as NOx, poses a particular pollution control problem in diesel engines which operate with a generally lean air-fuel mixture.

Selective catalytic reduction, known as SCR "Selective Catalytic Reduction" in English, causes a selective reduction of NOx in nitrogen and water, in the presence of a specific catalyst and by the action of a reducing agent. The reducing agent used is usually ammonia. Ammonia comes from the chemical decomposition of a reagent, typically urea, which is injected into the exhaust line in an aqueous form composed of a mixture of water and urea (sold in Europe under the brand deposited "AdBlue"). This reactive mixture of water and urea is stored in a specific tank of the vehicle which must have a sufficient capacity to allow good autonomy of the vehicle. Given its large volume and the fact that the heat engine is generally housed at the front of the vehicle, this reagent mixture tank is very often installed at the rear of the vehicle, for example in the luggage compartment or under the floor of it.

An SCR exhaust gas post-treatment system requires a large number of electrical components which are intended for managing the injection of the reactive mixture, in particular a pump, a pressure sensor, a solenoid valve, a sensor. level, a temperature sensor, an injector and heating resistors to avoid freezing of the reactive mixture at low temperature. All of these components are controlled by an electronic control unit for the SCR system, also based on information and instructions from an engine control unit for the vehicle, generally located under the engine hood. A large number of electrical connections and wire connections are required in an SCR system, as different components of the system are located in the vehicle at remote locations. This results in numerous bundles of electrical wires between the front and rear of the vehicle which generate complexity and additional development and manufacturing costs.

The plaintiff, the company PEUGEOT CITROEN AUTOMOBILES SA, proposed in its patent FR2919666B1 a system for managing a distribution circuit of a reagent in a vehicle exhaust line whose specific architecture provides a satisfactory solution to the disadvantages set out above. In this patent, a multiplex link is proposed between a digital / analog interface, located near the reagent tank, and the vehicle engine control unit. The various sensors and actuators of the system are connected to the digital / analog interface and the processing and control means of the system are integrated in the engine control unit. This results in a considerable reduction in the number of connections by electric wires and a consequent reduction in development and manufacturing costs.

The upcoming entry into force of the European emission standard known as "Euro 6c" requires car manufacturers to integrate into SCR post-treatment systems a reagent quality sensor measuring the urea concentration in the aqueous reactive mixture. The effectiveness of the SCR process depends on a precise dosage of the amount of urea that is injected, the integration of such a sensor aims to facilitate the optimization of the functioning of the SCR system and to issue alerts when necessary. The driver of the vehicle must in fact be alerted to a deficiency in the exhaust aftertreatment function and thus be encouraged to carry out the necessary checks.

The integration of this additional sensor into existing SCR systems, already integrating a large number of components, poses a difficulty for car manufacturers. The reagent quality sensor must be in contact with the aqueous reagent mixture and must be electrically connected to the electrical circuit and to the control unit of the SCR system. This involves additional wire connections and additional development and manufacturing costs.

The Chinese utility model CN204591423U discloses a urea tank in which a urea quality sensor is integrated. Different locations of the urea quality sensor in the tank are described in this document. An electrical connector connected to the sensor is available outside the tank for electrical connection of the tank to the SCR system. The urea tank according to CN204591423U therefore requires an additional electrical cable to connect its urea quality sensor to the electrical circuit and to the control unit of the SCR system.

The present invention aims to provide a post-treatment system of the selective catalytic reduction type, equipped with a reagent quality sensor and requiring no additional wired connection to connect this sensor to the system control unit .

According to a first aspect, the invention relates to a system for post-treating the exhaust gases of a thermal engine of a motor vehicle, the system being of the selective catalytic reduction type and comprising a control unit, a reservoir of reactive mixture and a multiplexed digital link, the reactive mixture reservoir being equipped with a reservoir management circuit to which a plurality of sensors and a plurality of actuators are connected, and the reservoir management circuit being in communication with the control unit through the multiplexed digital link. According to the present invention, said plurality of sensors comprises a reagent quality sensor delivering information on the quality of the reactive mixture contained in the reservoir, this information on the quality of the reactive mixture being transmitted to the control unit through the multiplexed digital link.

Thanks to this design of the SCR system according to the invention, it is not necessary to add an electric cable between the electronic tank management circuit and the system control unit for the integration of the quality sensor. of reagent in the system.

According to a particular characteristic of the invention, the control unit includes an alert module delivering an alert when the quality of the reagent mixture indicated by the reagent quality information is below a predetermined quality threshold.

According to yet another particular characteristic of the invention, the control unit is housed in an engine control unit of the vehicle and is implemented in the form of a software module.

The realization of the system control unit in the form of a software module has the advantage of facilitating the integration of the reagent quality sensor in the system, the modification of the software code being less heavy in terms costs and deadlines as hardware modifications to electronic circuits.

According to yet another particular characteristic of the invention, the reagent quality sensor is housed in the reservoir and is in contact with the reagent mixture contained in the reservoir, the reagent quality sensor being connected to means d '' analog / digital interface of the tank management circuit.

With the architecture of the invention, the most substantial modifications imposed on the SCR system by the integration of the reagent quality sensor occur at the level of the reservoir in which the latter is implanted. However, this tank equipped with a reagent quality sensor is a standard equipment which can be used in a wide range of vehicles equipped with the SCR system according to the invention.

The location of the reagent quality sensor in the tank allows detection at the source of a possible quality problem of the reagent mixture and an early warning of the driver.

According to yet another particular characteristic of the invention, the tank is located at the luggage compartment of the vehicle or under the floor thereof.

According to yet another particular characteristic of the invention, the multiplexed digital link is a link established through a CAN type network.

According to a particular embodiment of the system according to the invention, the reactive mixture comprises water and urea and the reagent quality sensor is a urea quality sensor.

According to another particular characteristic of the invention, the urea quality sensor measures the concentration of urea in the reactive mixture.

In another aspect, the invention also relates to a motor vehicle comprising a heat engine and a system as briefly described above for post-treatment of the exhaust gases emitted by the heat engine. Typically, the heat engine is of the Diesel type.

Other advantages and characteristics of the present invention will appear more clearly on reading the description below of a particular embodiment of the invention, in which:

the single FIG. 1 appended hereto represents a block diagram of an after-treatment system SCR according to the invention, equipped with a reagent quality sensor.

The SCR exhaust gas post-treatment system according to the invention, referenced 1 in Fig.1, comprises a reservoir 2 containing an aqueous reactive mixture, typically a mixture of water and urea, intended to be injected into the exhaust gases.

For a reduction by SCR catalysis of NOx emissions from a diesel engine, this tank 2 will have a substantial capacity, typically of the order of 25 liters. Due to lack of space, this tank 2 cannot be housed under the engine cover of the vehicle near the engine and its engine control unit 3. The location under the engine cover of the engine control unit 3 is designated A in Fig. 1.

In the vast majority of motor vehicles, the tank 2 will be housed at the luggage compartment, at the rear of the vehicle, that is to say, generally in the trunk itself or under the floor from the trunk. The location of tank 2 is designated B in Fig. 1 and is distant from location A.

The system 1 includes injection means 4 provided for withdrawing a quantity of reactive mixture from the tank 2 and injecting it into the exhaust gases. The injection means 4 typically comprise a metering pump controlled as a function of the pressure requirements in the injection circuit and an injector for the quantitative requirements of reactive mixture. In Fig.1, the arrow from the injection means 4 represents the injection into the exhaust gas of the quantity of reactive mixture required.

Typically, the aqueous reactive mixture of water and urea freezes around the temperature of -11 ° C. To prevent the reactive melaige from freezing, electrical heating means are provided in the system 1. There is thus provided a heating device 5 for heating the reactive mixture in the tank 2 and auxiliary heating devices 6 and 7 for heating a pipeline between the reservoir 2 and an injection point of the reactive mixture in the exhaust line and the pump of the injection means 4 also if necessary. Temperature sensors (not shown) are used in system 1 to determine the heating requirements of the reaction mixture in order to prevent it from freezing.

The system 1 also includes a level sensor of the reactive mixture 80 and a pressure sensor 81 which equip the tank 2 and are located in the block referenced 8 in Fig.1.

According to the invention, the system 1 also includes, in block 8 in FIG. 1, a reagent quality sensor 82, which is here a urea quality sensor. The reagent quality sensor 82 is placed in the reservoir 2 so that a measurement component sensitive to the urea concentration of the sensor is in contact with the reagent mixture. The reagent quality sensor 82 delivers information RQ indicating the quality of the reactive mixture contained in the tank 2. The quality measurement carried out by the sensor 82 comprises a measurement of the concentration of urea in the reactive mixture.

An electronic tank management circuit 9 is provided in the system 1 and is mounted on the tank 2 in this particular embodiment. This tank management circuit 9 typically comprises bidirectional analog / digital interface means 90 and bidirectional multiplexed digital link interface means 91.

In this particular embodiment, it is considered that all of the sensors 80, 81 and 82 and the actuating components 4 to 7 of the system 1 are of analog type, that is to say, that '' they output and / or receive as input in analog signals.

The various links 92 shown in Fig.1 connect the sensors 80, 81 and 82 and the actuating components 4 to 7 to an analog input / output port of the analog / digital interface means 90. L RQ information delivered by the urea quality sensor 82 is thus transmitted to the analog / digital interface means 90. The link 93 shown in FIG. 1 is a multi-wire digital link connecting a digital input / output port of the analog / digital interface means 90 to a digital input / output port corresponding to multiplexed digital link interface means 91.

As shown in FIG. 1, the tank management circuit 9 is connected to the engine control unit 3 by a digital multiplexed link 10 which is here a link established through a CAN type network. The multiplexed digital link 10 is connected at its two ends to digital input / output ports of the multiplexed digital link interface means 91 and of the multiplexed digital link interface means 30 of the engine control unit 3, respectively. All the signals acquired by the system 1 at the location B of the tank 2 can thus be transmitted to the engine control unit 3, and more precisely to a control unit 31 of the system 1 which is implemented in unit 3 in the form of a dedicated software module running therein.

The control unit 31 processes all of the signals and information necessary for an adapted control of the system 1. It will be noted here that some of these signals and information, such as for example the quantity of fuel injected, the quantity of fresh air and recirculated gas admitted into the cylinders, engine speed, required torque, etc., are available locally (location A) in the engine control unit 3 and are communicated directly by this to the engine control unit. control 31. The control unit 31 uses all of the signals originating from location B, through the multiplexed link 10, and the signals and information communicated locally by the unit 3 to define the adapted control of the system 1. This command from the system 1 is transmitted to the actuating means 4 to 7 through the multiplexed link 10.

According to the invention, the control unit 30 uses the reagent quality information RO to issue an alert WA when the quality of the reactive mixture indicated by the RO information is below a predetermined quality threshold. This WA alert is triggered by an alert module 301, included in the control unit 31, and aims to warn the driver of the vehicle of a deficiency in the exhaust gas aftertreatment function and to encourage him to carry out the necessary checks. It will be noted that the reagent quality information RO is also used by the control unit 31 to define the suitable command transmitted to the actuation means 4 to 7 of the system 1.

Of course, the invention is not limited to the embodiment of the system according to the invention more particularly described here. A person skilled in the art, depending on the applications of the invention, can make various modifications and variants which fall within the scope of the appended claims.

Claims (10)

1. An exhaust gas post-treatment system for a thermal engine of a motor vehicle, said system (1) being of the selective catalytic reduction (SCR) type and comprising a control unit (31), a mixing tank reagent (2) and a multiplexed digital link (10), said reagent mixing tank (2) being equipped with a tank management circuit (9) to which are connected a plurality of sensors (80, 81) and a plurality of actuators (4, 5, 6, 7), and said tank management circuit (9) being in communication with said control unit (31) through said multiplexed digital link (10), characterized in that said plurality of sensors comprises a reagent quality sensor (82) delivering information (RQ) on the quality of the reactive mixture contained in said tank (2), said information (RQ) on the quality of the reactive mixture being transmitted to said control unit ( 31) to tr towards said multiplexed digital link (10). 2. System according to claim 1, characterized in that said control unit (31) comprises an alert module (301) delivering an alert (WA) when the quality of the reactive mixture indicated by said information (RQ) is less than a predetermined quality threshold. 3. System according to claim 1 or 2, characterized in that said control unit (31) is housed in an engine control unit (3) of the vehicle and is implemented in the form of a software module. 4. System according to any one of claims 1 to 3, characterized in that said reagent quality sensor (82) is housed in said tank (2) and is in contact with the reactive mixture contained in said tank (2) , said reagent quality sensor (82) being connected to analog / digital interface means (90) of said reservoir management circuit (9). 5. System according to any one of claims 1 to 4, characterized in that said tank (2) is located at the luggage compartment of the vehicle or under a floor thereof. 6. System according to any one of claims 1 to 5, characterized in that said multiplexed digital link (10) is a link established through a CAN type network. 7. System according to any one of claims 1 to 6, characterized in that 5 said reagent mixture comprises water and urea and said reagent quality sensor (82) is a urea quality sensor. 8. System according to claim 7, characterized in that said urea quality sensor performs a measurement of the concentration of urea in the reactive mixture. 9. Motor vehicle comprising a heat engine, characterized in that it 10 comprises a system according to any one of claims 1 to 8 for an aftertreatment of the exhaust gases emitted by said heat engine. 10. Motor vehicle according to claim 9, characterized in that said heat engine is of the Diesel type. 1/1