FR2887302A1 - Additive forming unit introducing device for motor vehicle fuel tank, has control case associated to units analyzing moving conditions of vehicle to control pump and injector to adapt additive concentration in fuel to conditions - Google Patents

Abstract

The device has pollution control units disposed in the exhaust line of a diesel engine (1) of a motor vehicle comprising an additive tank (10) and a fuel tank (2). A metering pump (13) and an injector (14) are connected to the tanks. An electronic control case (20) controls the pump and the injector to inject the additives. The case is associated to moving conditions analyzing units (30) of the vehicle to control the pump and the injector, so as to adapt the additive concentration in the fuel to the conditions favorable or unfavorable to the regeneration of the pollution control units.

Description

The present invention relates to a device for automatic introduction of

  additive means in the fuel tank of a motor vehicle.

  The exhaust gases of compression-ignition engines, and in particular diesel engines which use diesel as fuel, contain both gaseous pollutants such as hydrocarbons, nitrogen oxides and carbon monoxide CO and solid pollutants which mainly consist of soot particles.

  The anti-pollution standards applied to diesel engines are becoming more stringent and require the almost complete elimination of emissions of soot particles in the exhaust gases of these engines.

  To ensure the elimination of these soot particles, motor vehicle manufacturers are required to provide a post-treatment of the exhaust gas including using a particulate filter.

  Such a filter is installed in the exhaust line of the engine and comprises porous ceramic filter elements which are traversed by the exhaust gas and which make it possible to retain the solid particles suspended in these gases.

  During the operation of the engine, the filter elements are loaded into soot particles and clog gradually. Unclogging of the filter elements can be achieved by burning the soot deposited on these elements during operation of the engine.

  In the presence of oxygen, the soot burns at temperatures of the order of 550 to 600 C. Such thermal levels are only rarely reached by the exhaust gas of a diesel engine of a passenger vehicle. It is therefore necessary to promote the start of the regeneration of the filter elements, by adding to the fuel means forming an additive allowing in particular to lower the soot combustion temperature.

  The most commonly used additives consist of organometallic compounds which, mixed in specific proportions with diesel, are injected into the combustion chamber, by the injection pump, and are found in the exhaust gas.

  The presence of these additives in the particulate filter, intimately mixed with the soot particles, allows them to act as a catalyst for the combustion of soot particles and to lower the soot ignition temperatures to around 400 at 450 C.

  One solution that has been envisaged is to mix these additives with diesel, at the end of the industrial process of obtaining the fuel, in the oil producing factories. The diesel fuel containing the particulate filter regeneration additives would then be sold at the pump and would constitute a particular product in the context of the retail sale of fuels.

  The disadvantage of such a method and the corresponding organization of the sale is to require the provision of an additional variety of fuel and to cause a complete dependence of the users and manufacturers of the engines, vis-à-vis the choices made by the petroleum industry, as regards the nature of the additives and the composition of the additive mixtures retained.

  Indeed, it may be necessary to adapt the composition of the additives to the characteristics of the engine in which they are used.

  Another known solution is to incorporate the additives to the fuel, automatically, inside the vehicle tank after each filling operations of this tank.

  The dosage of the additives is carried out so that the concentration of fuel additive inside the tank remains perfectly constant.

  As they pass through the engine's combustion chamber, the organometallic additives become metal oxide particles intimately mixed with the soot particles.

  The predetermined concentration of the additive in the fuel is set at a value such that the fuel injected into the engine cylinders constantly contains an amount of additive sufficient to lower the soot combustion temperature in the particulate filter of the vehicle, up to at a level ensuring satisfactory combustion even when the engine load level is low.

  For this purpose, in order to determine the quantity of additive to be injected into the fuel tank of the vehicle, the initial level of the fuel in the tank is measured, prior to each replenishment operation of this tank, the final level of the fuel in the tank is measured. the tank and determines, on the one hand, the amount of fuel introduced into the tank at each replenishment operation from the initial level and the final level measured and, secondly, the amount of additive contained in a quantity fuel equal to the amount introduced into said tank.

  The measurement and recording of the fuel level in the tank are automatically controlled when opening and closing a filling cap of the tank filling pipe or when opening and closing a shutter of a portion of the vehicle body giving access to filling means of the tank.

  The amount of additive means injected at the present time, is determined so as to obtain permanently in the fuel tank, an additive rate of the order of 10 ppm.

  There is indeed an optimal mass of additive mass on carbon mass ratio of 1.4% with the current additive means. It is not necessary to go beyond this, because the regeneration is sufficiently efficient. To deviate too much from it could even in some cases be detrimental to the mechanical strength of the particulate filter because of a risk of runaway regeneration.

  In fact, this ratio depends on the temperature of the gases reached in the regeneration phase, which itself is highly dependent on the running conditions of the vehicle. Thus, when the regeneration can be done on the motorway, it is relatively easy to obtain exhaust gas temperatures of 600 C in the particulate filter, the additive being then practically unnecessary. On the other hand, when the particle filter has to be regenerated during an urban run, the gas temperature reaches at best 450 ° C and the additive is then of great help.

  The additive dosage is now fixed and defined, so that we obtain an additive ratio on carbon of 1.4% in urban traffic. The current operation is therefore not optimized when the use of the vehicle is mostly extra-urban type.

  It is conceivable then that this results in an unnecessary additive consumption. The amount of additive present in the soot particles of the particulate filter is greater than necessary, because this type of rolling generates few particles and the dosage of additive necessary to regenerate this filter on the highway is very low. In this respect it should be noted that the consumption of additive conditions the maintenance of the particulate filter. A reduction in the dosage would make it possible to postpone the filling operation of the additive reservoir and also to repel the cleaning operation of the particulate filter (accumulated additive residues).

  Moreover, an overdose of additive can also lead to cracking or even to a breakage of the particulate filter.

  The object of the invention is therefore to solve these problems.

  To this end, the subject of the invention is a device for automatically introducing means forming an additive into the fuel tank of a motor vehicle comprising pollution control means arranged in the exhaust line of the engine of the vehicle and comprising a reservoir. for the additive means, additive injection means connected to the additive tank and to the fuel tank and means for controlling the injection means for carrying out the injection of additive, characterized in that the means control means are associated with means for analyzing the running conditions of the vehicle, for controlling the operation of the injection means, in order to adapt the concentration of additive in the fuel to the running conditions of the vehicle.

  According to other characteristics: the control means comprise means for detecting rolling conditions that are favorable for regeneration of the depollution means in order to use a first concentration of additive in the fuel and rolling conditions that are unfavorable for regeneration of the means. depollution for using a second concentration of additive in the fuel; and the detection means of the driving conditions are adapted to detect favorable driving conditions on the motorway and unfavorable in the city.

  The invention will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which: FIG. 1 represents a block diagram illustrating the structure and operation an introducer device according to the invention; and FIGS. 2, 3, 4 and 5 are tables illustrating the strategies and the gains obtained thanks to such a device.

  FIG. 1 diagrammatically shows a diesel engine, generally designated by the reference 1, of a motor vehicle and which is supplied with diesel fuel from a tank 2, via a fuel pump. injection 3.

  The injection pump 3 is connected to the reservoir 2 by a suction pipe 4 on which is inserted a filter 5.

  The suction pipe 4 has an end portion opposite the pump 3 which is dipped inside the tank 2 to open, at its lower part, in the form of a suction strainer 6.

  In addition, the pump 3 is connected to the cylinders of the engine 1 by lines each providing the supply of an injector 9 associated with a cylinder of the engine.

  The tank 2 is equipped with a level gauge 7 to determine the position of the diesel fuel level in the tank 2.

  The tank 2 also comprises a filler pipe 8 opening into the upper part of this tank 2 and equipped with a closure cap 8a.

  The exhaust line of the vehicle, whose propulsion is provided by the diesel engine, comprises a particulate filter, not shown, for stopping the soot particles formed in the exhaust gas of the engine.

  The vehicle comprises an additive tank 10 provided with a filling plug 11 and intended to contain additive means which may consist of one or more organometallic compounds in solution in a liquid solvent.

  A liquid additive injection line 12 is connected to the additive reservoir 10, in the vicinity of its lower part. A metering pump 13 is interposed on the pipe 12 which is connected, at its end opposite the additive reservoir 10, to an injector 14 opening directly into the fuel tank 2.

  A return line 15 communicating with the injection line 12, downstream of the pump 13, is connected to the upper part of the additive tank 10. A pressure regulator 16 constituted by a ball valve comprising a setting spring is interposed on the return pipe 15.

  The automatic additive introduction device according to the invention comprises an electronic control unit 20 integrated in the vehicle and making it possible to provide all the adjustment and monitoring functions of the introduction of additive in metered quantities into the fuel tank. fuel 2 of the vehicle.

  The automatic additive introduction device also comprises means for measuring the amount of fuel introduced into the reservoir 2 during each replenishment operation.

  As shown in the figure, these measuring means are formed for example by a mono-directional flowmeter 17 placed directly in the tubing 8 for filling the fuel tank 2.

  The flowmeter 17 is connected to the control unit 20 by an electric cable 21 which automatically transmits to said housing 20 the amount of fuel introduced into the tank 2 when refilling this tank 2 with fuel.

  The level gauge 7 associated with the fuel tank 2 is connected by an electric cable 22 to the housing 20, so as to transmit to this housing 20 as well as to the driver of the vehicle, an electric signal representative of the fuel level inside. of said tank 2.

  The electronic box 20 is connected by electric cables, respectively 23 and 24, to the pump 13 and the injector 14, so as to transmit to these elements of the additive introduction device a control signal ensuring an injection into metered quantity of additive in the tank 2 of fuel, under the conditions which will be described later.

  A level gauge 18 connected to the control unit 20 by an electric cable 25 makes it possible to transmit to this housing 20 an electrical signal when the level of additive in the tank 10 has reached a minimum position close to the bottom of this tank 10.

  A temperature sensor 19 disposed in the additive reservoir 10 makes it possible to transmit to the electronic control unit 20, via an electric cable 26, a signal representative of the temperature of this liquid additive inside said reservoir 10.

  The electronic unit 20 comprises at least one output 27 constituted by at least one electrical cable connected to lights which can be located advantageously in the passenger compartment of the motor vehicle.

  The ignition of a first indicator is obtained when the level of additive detected by the gauge 18 in the additive reservoir 10 has reached the position corresponding to the minimum level near the bottom of the reservoir 10 and the ignition of a second indicator light is obtained when the level of fuel detected by the gauge 7 in the fuel tank 2 has reached a position corresponding to the minimum level close to the bottom of this fuel tank 2.

  The electronic unit 20 also receives, as input data, an electrical signal representative of the concentration of additive that it is necessary to maintain in the fuel, that is to say in the diesel fuel injected into the cylinders 9 of the engine 1. depending on the driving conditions of the vehicle.

  In fact, this concentration of additive depends on the driving conditions of the vehicle.

  For example, means 30 for analyzing the running conditions of the vehicle and for determining vehicle running conditions that are favorable or unfavorable for the regeneration of the depollution means, are used to deliver to this electronic box 20 a nominal metering information corresponding to unfavorable driving conditions, for example of urban type, or minimal metering information, corresponding to favorable driving conditions, for example on the motorway.

  This information is for example delivered by storage means designated by the general references 31 and 32 in this FIG. 1, which then deliver, according to the rolling conditions encountered, the nominal dosing information or the minimum dosing information to the casing. electrical 20 to drive accordingly the additive injection means.

  The interest of this adaptation appears from the analysis of the table of Figure 2, which shows the necessary ratios and effective ratios according to driving conditions, implemented in the state of the art.

  Thanks to the device according to the invention, it is therefore possible to establish the concentration of additive in the fuel at the value just needed.

  By taking over the structure and operation of an already existing introduction device of the state of the art, it is already possible to optimize the injection of additive. The diesel can indeed be additivé in two stages, a first time during a replenishment and a second time, if this is deemed necessary after analysis of the driving conditions of the vehicle.

  In the device according to the invention, it is indeed possible to implement the two dosages indicated above, namely the nominal dosage corresponding to the rolling conditions unfavorable to the regeneration and already implemented in the devices for introducing the state. of the technique, and the minimum dosage adapted to conditions favorable to regeneration, such as for example when driving on the motorway.

  This analysis of the driving conditions of the vehicle may for example be based on an analysis of a driving history of the vehicle. Thus, for example, if the use of the vehicle over the last 50 kilometers traveled corresponds to a taxi in town, then the additive is injected at the nominal dosage. In the opposite case, that is to say for example if the vehicle is used on the highway, it is possible to inject the minimum dosage.

  In this case, and if the means for analyzing the running conditions of the vehicle detect a change in conditions, such as for example a transition from a highway taxi to a city taxi, we can inject an additional amount of additive to bring the concentration to the nominal dosage value.

  Such a strategy makes it possible, for example, for vehicles essentially traveling on motorways, to operate mainly with a minimum dosage of additive.

  A first strategy for choosing the minimum dosage is illustrated in the table of FIG. 3. This minimum dosage is chosen so that the additive-to-carbon ratio is constant regardless of the type of rolling. In the illustrated example, this is dose on the highway at 6 ppm instead of 10 ppm. When returning to urban use, the soot in the particulate filter is correctly additive.

  Figure 4 shows a table illustrating a second minimal dosage choice strategy. The minimum highway dosage is lowered to the level just needed to regenerate under these favorable driving conditions.

  In the example given, the highway is thus measured at 2 ppm instead of 10 ppm, which represents a very significant gain in durability for the customer.

  A difficulty in this case is that during a return to urban use, the soot in the particulate filter are sub-additive and it is impossible to add the additive later in the soot. This can then lead to a difficulty in burning these soot. But such a case is rare, because after a runway road / highway, the particle filter usually contains little soot. In fact, either they burned naturally thanks to the temperatures reached on the highway, or the operating supervisor of the particulate filter took advantage of the favorable conditions to trigger the regeneration in an anticipated manner. In addition, soot accumulated subsequently during a taxi in the city have the right dosage which allows to initiate combustion in the particulate filter. Moreover, the possible problem concerns only one regeneration in the city. Indeed, if the vehicle stays longer in town, the dosage then becomes nominal for subsequent regenerations.

  A possible alternative is to trigger an exceptionally regeneration at a higher temperature to compensate for the underdosing additive, considering that the impacts in consumption and dilution are bearable because exceptional and not critical for a vehicle traveling in the city.

  If necessary, we can also choose to reserve this economic strategy for vehicles with less than 20% of city. For this, we can for example record, over the last 5000 kilometers traveled, the urban use rate and compare it to a threshold value.

  The table in Figure 5 shows that the gain in additive consumed is considerable especially for the second strategy but is also interesting for the first strategy.

  It goes without saying that such a device is adaptive and works even if the vehicle changes ownership and use. Indeed, a vehicle can at the beginning of life travel a lot of highway, then make a lot of city.

  The bonus acquired at the beginning of life is preserved in some way in the form of an additive not consumed subsequently.

  Some elements of the additive introduction device may be constituted by elements conventionally used for the construction of motor vehicle engines and their control members.

  Thus, the additive injection assembly comprising the pump 13, the pressure regulator 16 and optionally the injector 14 can be constituted by a conventional injection device as used on motor vehicles comprising a injection engine.

  Referring now again to Figure 1, will be described the operation of the automatic additive introduction device in the fuel tank of the motor vehicle.

  When the user of the vehicle replenishes the tank 2 with fuel, he introduces the pump gun into the filler neck 8.

  Thus, during the flow of fuel in this pipe 8, the flowmeter 17 directly measures, in the pipe 8, the amount of fuel introduced into the tank 2.

  The flowmeter 17 therefore transmits through the electric cable 21 the signal representative of the quantity of fuel introduced into the tank 2.

  At the start of the engine 1, the electrical contact of the vehicle makes it possible to put into operation the electronic control unit 20 for determining and carrying out the injection of additive into the fuel tank 2.

  For this purpose, the control unit 20 calculates the quantity of additive to be introduced into the tank 2, as a function of the quantity of fuel introduced into this tank 2 and the concentration of additive of the fuel delivered by the means of fuel. analyzing the driving conditions 30, 31, 32 to obtain satisfactory operating conditions of the particulate filter.

  The signal representative of the quantity of additive to be introduced into the fuel tank 2 is converted into a control signal of the injection pump 13 and to a control signal of the injector 14.

  The control signal of the injector 14 keeps the injector open for a time sufficient to effect the injection of the determined amount of constant pressure additive into the fuel tank 2, the pump 13 remaining in operation for a time sufficient to carry out this injection directly into said fuel tank 2.

  At the end of the injection of additive, the gas oil contained in the tank 2 has an additive concentration which corresponds perfectly to the concentration necessary to obtain a satisfactory operation of the particulate filter according to the determined driving conditions.

  In addition, the concentration of additive of the gas oil in the tank 2 is perfectly homogeneous due to the mixing provided by the injection pump 3.

  The engine 1 and the particulate filter associated with it in the exhaust line can then operate under satisfactory conditions.

  The temperature of the additive injected directly into the tank 2 can be adjusted by virtue of the temperature gauge 19 and a circuit for heating the additive in the tank 10.

  According to one variant, the temperature measured by the gauge 19 can be taken into account by the control unit 20 to calculate the injection time of the additive at constant temperature. Indeed, the injection time of a fixed amount of additive at constant pressure varies depending on the viscosity, therefore the temperature of this additive.

  The method and the device according to the invention make it possible to maintain in the vehicle fuel tank an additive concentration adapted to the operating conditions of the engine.

  Thus, the particulate filter operates under satisfactory conditions with respect to its regeneration.

  It is simply necessary to maintain a sufficient level of additive in the corresponding reservoir which requires replenishment of the reservoir when the minimum level indicator lights.

  The capacity of the tank can be determined accordingly. Compared to the devices used until now, the device according to the invention simplifies the embedded software and reduce the size of the memories of this software.

  In addition, the reliability of operation is greater compared to the devices used since the device according to the invention no longer takes account of the gauging and its errors.

  Finally, the metering accuracy of the additive in the fuel is increased and the metering accuracy becomes constant regardless of the fuel supply.

  The electronic box can be made using any component or microprocessor and employing the usual knowledge of the technicians in the field of electronics.

  The gauges or temperature probes used may be of any type suitable for the measurements made and the environment in which these measurements take place.

  The first and second strategies described above are relatively simple to implement. These adaptive dosing strategies then provide a real benefit for a large proportion of vehicles.

  Of course, other embodiments can be envisaged.

  For example, replenishment tracking can be provided by the fuel level gauge.

  Similarly, the housing 20 may be integrated wholly or partly into a computer already on board the vehicle such as a motor or other computer.

Claims (3)

  1. Device for automatically introducing additive means into the fuel tank (2) of a motor vehicle comprising pollution control means arranged in the exhaust line of the engine (1) of the vehicle and comprising a reservoir (10) for the additive means, additive injection means (13, 14) connected to the additive reservoir (10) and to the fuel tank (2) and means (20) for controlling the means (13, 14). ) for injecting the additive, characterized in that the control means (20) are associated with means (30) for analyzing the running conditions of the vehicle, for controlling the operation of the means of injection (13, 14), in order to adapt the concentration of additive in the fuel to the running conditions of the vehicle.   2. Device according to claim 1, characterized in that the control means comprises means (30, 31, 32) for detecting rolling conditions favorable to a regeneration of the depollution means for using a first concentration of additive in the fuel and running conditions unfavorable to a regeneration of the depollution means for using a second concentration of additive in the fuel.   3. Device according to claim 1 or 2, characterized in that the means (30, 31, 32) for detecting rolling conditions are adapted to detect favorable driving conditions on the highway and unfavorable in the city.