FR2668203A1 - Method and device for the automatic introduction of an additive into the fuel tank of a motor vehicle, and their use in the case of a vehicle with a diesel engine - Google Patents

Abstract

The initial level of fuel in the tank (2) is measured prior to each operation of refilling the tank (2) with fuel. The final level of fuel in the tank (2) is measured at the end of each of the refilling operations. The quanity of fuel introduced into the tank (2) during each of the refilling operations is determined, and the amount of additive necessary to maintain the concentration of additive in the fuel at a fixed predetermined value is determined. The previously determined amount of additive is automatically injected into the tank. The invention applies particularly to the introduction into a diesel fuel tank (2), of an additive making it possible to lower the ignition tempreature of the soot in a particle filter of a motor vehicle with a diesel engine.

Description

 The invention relates to a method and a device for automatically introducing an additive in metered quantity into the fuel tank of a motor vehicle and the use of this method and of this device in the case of a motor vehicle. Diesel, to ensure the dosage of an additive to lower the ignition temperature of soot in a particulate filter on the vehicle's exhaust system.

 Exhaust gases from diesel engines which use diesel as fuel contain both gaseous pollutants such as hydrocarbons, oxides of nitrogen and carbon monoxide CO and solid pollutants which are mainly constituted by particles of soot. The anti-pollution standards applied to diesel engines will require, in the more or less near future, the virtually complete elimination of emissions of soot particles in the exhaust gases of these engines.

 To ensure the elimination of these soot particles, it is necessary to carry out an aftertreatment of the exhaust gases using a particle filter.

 Such a filter is installed in the exhaust line of the engine and comprises filtration elements made of porous ceramic material which are crossed by the exhaust gases and which make it possible to retain the solid particles in suspension in these gases.

 During engine operation, the filter elements become charged with soot particles and gradually clog up. The filter elements can be unclogged by burning the soot deposited on these elements during engine operation.

 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 gases from a diesel engine of a passenger vehicle. It is therefore necessary to encourage the start of the regeneration of the filtration elements, by adding to the fuel an additive making it possible to lower the soot regeneration temperature.

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

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

 To play their catalytic role perfectly, the additives must be homogeneously mixed with the diesel fuel used as fuel.

 Up to now, it has been envisaged to mix these additives with diesel, at the end of the industrial process of obtaining fuel, in the producing oil factories. The diesel fuel containing the regeneration additives of the particulate filters would then be sold at the pump and would constitute a specific product, within the framework of the retail sale of fuels.

 The disadvantage of such a process and of the corresponding organization of the sale is that it requires the provision of an additional variety of fuel and entails complete dependence on the choices made by the users and the engine manufacturers. by the petroleum industry, with regard to the nature of the additives and the composition of the additive mixtures used.

 It may indeed be necessary to adapt the composition of the additives to the characteristics of the engine in which they are used.

 More generally, it may be necessary to have a method and a device for the metered introduction of an additive of any kind into the fuel tank of a motor vehicle.

 The object of the invention is therefore to propose a process for the automatic introduction in metered quantity of an additive into the fuel tank of a motor vehicle, so as to maintain at a predetermined value the concentration of the additive in the fuel contained in the tank, this process making it possible to avoid any metering error and any defective use of the vehicle as a result of the user's negligence, without having to use a fuel of a particular nature distributed to the pump.

 For this purpose - the initial level of fuel in the tank is measured, prior to each refueling operation of the fuel tank, - the final level of fuel in the tank is measured at the end of each refueling operation, - determines the quantity of fuel introduced into the tank during each replenishment operation, from the initial level and the final level measured, - the quantity of additive contained in a quantity of fuel is determined equal to the quantity introduced into the tank and the additive content of which corresponds to the predetermined concentration, and - the quantity of additive previously determined is injected into the vehicle tank.

 The invention also relates to a device for automatically introducing an additive into the fuel tank of a motor vehicle and to the use of a method and a device according to the invention for introducing an additive of regeneration of a particulate filter of a diesel engine vehicle, in the diesel tank of this vehicle.

 The single figure is a schematic view showing a device for introducing in metered quantity, an additive making it possible to promote the regeneration of a particulate filter of a diesel engine vehicle, in the diesel tank of this vehicle.

 In the figure, we see the Diesel engine 1 of a motor vehicle which is supplied with diesel fuel, from a tank 2, by means of an injection pump 3.

 The pump 3 is connected to the tank 2 by a suction pipe 4 on which a filter 5 is inserted. The suction pipe 4 has an end portion opposite to the pump 3 which is plunged inside the tank 2 to open, at its lower part, in the form of a suction strainer 6.

 The pump 3 is also connected to the diesel tank 2, by means of a return pipe 7 making it possible to return to the tank 2 the excess quantities of diesel drawn by the pump which have not been injected into the cylinders of the motor 1.

 The pump 3 is connected to the engine cylinders by lines each supplying an injector 9 associated with an engine cylinder.

 The tank 2 is equipped with a level gauge 8 making it possible to determine, in a precise manner, the position of the upper level of the diesel fuel in the tank 2.

 The reservoir 2 comprises a filling tube 11 opening into the upper part of the reservoir 2 and equipped with a closure cap 12.

 The exhaust line of the vehicle, the propulsion of which is provided by the diesel engine 1, includes a particle filter, not shown, which makes it possible to stop the soot particles formed in the engine exhaust gases.

 According to the invention, the vehicle comprises an additive reservoir 14 provided with a filling plug 15 intended to contain an additive which may consist of one or more organo-metallic compounds in solution in a liquid solvent. A liquid additive injection pipe 16 is connected to the reservoir 14, in the vicinity of its lower part. A metering pump 18 is interposed on the line 16 which is connected, at its end opposite to the reservoir 14, to an injector 20 opening into the return line 7 of the injection pump 3 of the engine.

 A return line 21 communicating with the injection line 16 downstream of the pump 18 is connected to the upper part of the additive reservoir 14.

A pressure regulator 22 constituted by a ball valve comprising a calibration spring is interposed on the return line 21.

 The automatic additive introduction device according to the invention comprises an electronic control unit 24 integrated into the vehicle making it possible to perform all the adjustment and monitoring functions for the introduction of additive in metered quantity, into the tank 2 of the vehicle.

 An electrical contactor 25 associated with the cap 12 for closing the reservoir 2 and connected to the electronic unit 24 by an electrical cable 26 makes it possible to automatically transmit to the unit 24, an electrical opening signal, when the cap 12 is opened, prior to the refueling of tank 2.

 The contactor 25 can advantageously be produced in a form identical to a contactor used to detect the opening of a door and to cause the lighting of a pilot lamp, when the door is opened.

 The level gauge 8 is connected by an electric cable 27 to the housing 24, so as to transmit to the housing 24, an electrical signal representative of the fuel level 28 inside the tank 2.

 The electronic unit 24 is connected by electric cables 29 and 30 respectively, to the pump 18 and to the injector 20, so as to transmit to these elements of the additive introduction device, a control signal ensuring an injection in metered quantity of additive in the return duct 7 connected to the reservoir 2, under the conditions which will be described below.

 A level gauge 32 connected to the housing 24 by an electrical cable 33 makes it possible to transmit to the housing 24, an electrical signal when the level of additive in the reservoir 14 has reached a minimum position close to the bottom of the reservoir 14.

 A temperature probe 34 enables a signal representative of the temperature of the liquid additive inside the reservoir 14 to be transmitted to the housing 24, by means of an electric cable 35.

 The housing 24 has an outlet 36 constituted by an electric cable connected to an indicator which can advantageously be located in the passenger compartment of the motor vehicle and the ignition of which is obtained when the level of additive detected by the gauge 32 in the tank 14 has reached the position corresponding to the minimum level near the bottom of the tank 14.

 Illumination of the warning lamp indicates to the user that it is necessary to replenish the additive reservoir 14.

 The box 24 also receives as input data, an electrical signal representative of the predetermined concentration of additive which it is necessary to maintain in the diesel fuel injected into the cylinders of the engine.

 This data relating to the concentration of fuel additive can also be determined a priori and correspond to a fixed value whatever the conditions of use of the engine. In this case, the components of the electronic unit are provided so as to take this predetermined and invariable value into account.

 Certain elements of the additive introduction device according to the invention can 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 18, the pressure regulator 22 and possibly the injector 20 can be constituted by a petrol injection device as used on motor vehicles. comprising an injection engine.

 We will now describe the operation of the device according to the invention shown in the figure and making it possible to keep the concentration of additive in the fuel contained in the tank 2 constant.

 When the plug 12 is opened, before the tank 2 is replenished with fuel, the contactor 25 transmits an electrical signal to the box 24. This electrical signal makes it possible to initialize the electronic box 24 and to detect the start of a tank replenishment 2.

The contactor 25 which can be produced in the form of a microswitch automatically transmits an electrical signal which is received by the housing 24, as soon as an operation for opening the plug 12 is carried out.

 The level gauge 8 supplies the housing 24, via the cable 27, with a continuous signal representative of the level 28 of the fuel in the tank 2. This continuous signal is recorded by the housing 24 only when the initialization signal from the contactor 25 has been received by the housing 24.

 After sending the initialization signal, the box 24 therefore automatically records a signal representative of the starting level of the fuel in the tank 2, before filling.

 The tank 2 is then replenished with fuel, which results in an increase in the level 28. The gauge 8 continuously supplies the housing 24 with an electrical signal representative of the level 28 in the tank 2. This electrical signal is however not taken into account and recorded by the box 24 only when the plug 12 is closed, which results in the interruption of the electrical signal coming from the contactor 25.

 The level recorded by the housing 24 after closing the cap 12 corresponds to the level in the tank 2, at the end of the filling operation.

 When the engine 1 is restarted, the vehicle's electrical contact makes it possible to operate the unit 24 for determining and carrying out the injection of additive into the fuel tank 2.

The control unit 24 performs the calculation of the amount of fuel introduced into the tank 2 of the vehicle during filling, from the initial level and the final level of fuel measured by the gauge 8 and recorded by the control module 24. The control module 24 also performs the calculation of the amount of additive to be introduced into the tank 2, as a function of the amount of fuel introduced into the tank and of the predetermined concentration of additive in the fuel, in order to obtain satisfactory operating conditions of the particle filter.

 The signal representative of the quantity of additive to be introduced into the reservoir is transformed into a control signal from the injection pump 18 and into a control signal from the injector 20.

 The injector 20 control signal keeps this injector open for a time sufficient to carry out the injection of the determined quantity of additive at constant pressure, the pump 18 remaining in operation for a sufficient time to carry out the injection. .

 The injection is carried out in the return line 7, the liquid additive being discharged into the tank 2, by the injection pump 3, with the excess flow of diesel fuel circulating in the line 7.

 At the end of the additive injection, the diesel fuel contained in the tank 2 has an additive concentration which corresponds perfectly to the predetermined concentration necessary to obtain satisfactory operation of the particle filter.

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

 The engine 1 and the associated particulate filter can then operate under satisfactory conditions.

 The temperature of the additive injected into the pipe 7 and the tank 2 can be adjusted using the temperature gauge 34 and a circuit for bringing the additive to temperature in the tank 14.

 Alternatively, the temperature measured by the gauge 34 can be taken into account in the module 24 to calculate the injection time of the additive at constant pressure. In fact, the injection time of a determined quantity of additive at constant pressure varies as a function of the viscosity, therefore of the temperature of the additive.

 The method according to the invention makes it possible to maintain in the vehicle fuel tank, a perfectly constant concentration of additive, whatever the operating conditions of the engine.

 The particulate filter therefore operates under satisfactory conditions with regard to its regeneration, regardless of the vehicle's refueling operations.

 It is simply necessary to maintain a sufficient level of additive in the reservoir 14, which requires carrying out a replenishment of this reservoir, when the minimum level indicator light comes on.

The capacity of the reservoir 14 can be provided for a range of approximately 100,000 km.

 It should be noted that the injection of additive is carried out in the low-pressure discharge part of the diesel circuit, which facilitates this injection.

 The invention is not limited to the embodiment which has been described.

 This is how additive injection means can be used which are different from those which have been described, the injection being able to be carried out for example directly into the fuel tank.

 The electronic unit 24 making it possible to record the level measurements and to carry out the calculation of the quantities of fuel introduced into the tank as well as the corresponding quantities of additive necessary to maintain the concentration of the fuel in additive can be produced using any component or microprocessor and using the usual knowledge of technicians in the field of electronics.

 The gauges or temperature probes used can be of any type adapted to the measurements made and to the environment in which these measurements take place.

 The initialization of the electronic unit and the control of the measurement or recording operations of the fuel level in the tank can be ensured, in the case of a vehicle comprising a hatch arranged in a part of its bodywork and giving access to means for filling the tank, by maneuvers for opening and closing the hatch which can be actuated, for example, by a lever located in the passenger compartment of the vehicle.

 The method and the device of the invention can be used not only to ensure that the additive content of the diesel fuel used as fuel for a diesel engine of a vehicle comprising a particle filter is kept at a constant value, but also for introducing any additive in metered quantity into the fuel tank of a motor vehicle, so as to keep the additive content of the fuel perfectly constant, whether this fuel consists of diesel, petrol or any other similar product .

Claims (17)

 1.- Process for the automatic introduction in metered quantity of an additive into the fuel tank (2) of a motor vehicle, so as to maintain the concentration of the additive in the fuel contained in the tank at a predetermined value (2), characterized by the fact - that the initial level (28) of the fuel in the tank (2) is measured, before each refueling operation of the tank (2), - that the final level is measured (28) of fuel in the tank (2), at 1 after each of the replenishment operations, - that the quantity of fuel introduced into the tank (2), during each of the replenishment operations, is determined from the initial level and the final level measured, - the quantity of additive contained in a quantity of fuel equal to the quantity introduced into the tank (2) and whose additive content corresponds to the concentration is determined predetermined, and - that is injected into the tank (2) of the vehicle, automatically, the amount of additive previously determined.  2.- Method according to claim 1, characterized in that the level (28) of the fuel in the tank (2) is measured continuously and that the measured values of the level (28) are recorded prior to each operation of replenishment of the tank (2) with fuel and at the end of each replenishment operation, the quantity of fuel introduced into the tank (2) during each of the replenishment operations being determined from the recorded values.  3.- Method according to any one of claims 1 and 2, characterized in that the measurement or recording of the level (28) of fuel in the tank (2) are controlled automatically, upon opening and closing a plug (12) for closing a filling duct (11) of the reservoir (2).  4.- Method according to any one of claims 1 and 2, characterized in that the measurement or recording of the fuel level in the tank (2) are controlled automatically, when opening and closing of a shutter hatch of a part of the vehicle body giving access to means for filling the tank (2).  5.- Method according to any one of claims 1 to 4, characterized in that the injection of additive into the tank (2) of the vehicle is carried out at constant pressure.  6.- Method according to any one of claims 1 to 5, characterized in that the injection of additive into the tank (2) of the vehicle is carried out by means of a pipe (7) connecting the tank (2) to the delivery part of a fuel injection pump (3) in the engine (1).  7.- Method according to any one of claims 1 to 6, characterized in that it constitutes an additive reserve (14) and that it detects the appearance of a minimum level of the additive in the reserve (14), automatically.  8.- Method according to claim 7, characterized in that the temperature of the additive in the reserve (14) is measured and that the injection time of the additive is determined, as a function of the measured temperature .  9.- Device for the automatic introduction in metered quantity of an additive into the fuel tank (2) of a motor vehicle, so as to maintain the concentration of the additive in the fuel contained in the tank at a predetermined value (2), characterized in that it is integrated into the vehicle and that it comprises an additive reservoir (14), additive injection means (18, 16, 20) connected on the one hand to the tank (14) of additive and on the other hand to the fuel tank (2) and measuring, calculation and control means (24) connected to a gauge (8) for measuring the level of fuel in the tank ( 2) making it possible to calculate the quantity of fuel introduced into the tank (2) at each refueling operation of this tank, the corresponding quantity of additive to be injected into the tank (2) to maintain the concentration of additive in the fuel contained in the tank (2) at a predetermined value e t controlling the injection means (18, 16, 20) to carry out the injection of the quantity of additive calculated.  10.- Device according to claim 9, characterized in that it further comprises an electrical contactor (25) associated with a plug or a filling hatch (12) of the reservoir (2) connected to the measuring means, calculation and control (24), so as to initialize these means (24) and to control the measurement or recording of the level (28) in the tank (2), when the cap is opened and closed or the filling hatch (12).  11.- Device according to any one of claims 9 and 10, characterized in that the additive tank (14) is equipped with a gauge (34) for measuring the temperature of the additive in the tank ( 14) and a gauge (32) for detecting a minimum level of additive in the reservoir (14), both connected to the measurement, calculation and control means (24).  12.- Device according to any one of claims 9 to 11, characterized in that the additive injection means comprise a pump (18) and an injector (20) arranged one after the another on a pipe (16) connected to the additive reservoir (14).  13.- Device according to claim 12, characterized in that the injection means further comprise a pressure regulator (22) disposed on a line (21) connecting the reservoir (14) to the line (16), downstream of the pump (18).  14.- Device according to any one of claims 12 and 13, characterized in that the injector (20) opens into a line (7) connecting the reservoir (2) to the discharge part of a pump (3 ) injecting fuel into the engine (1).  15.- Use of a method or a device according to any one of claims 1 to 14 for the introduction into a diesel tank (2) of a diesel motor vehicle, of an additive allowing '' lower the ignition temperature of soot in a particulate filter placed on the vehicle's exhaust system.  16.- Use according to claim 15, characterized in that the additive consists of at least one organometallic compound.  17.- Use according to any one of claims 15 and 16, characterized in that the injection of additive into the tank (2) of diesel vehicle is carried out, via a line (7) return of diesel fuel to the tank (2) connecting the delivery part of an injection pump (3) of the diesel engine (1) to the diesel tank (2).