CN100413721C - Fuel system for an internal combustion engine - Google Patents

Abstract

A fuel system for an internal combustion engine using liquid fuel, comprising a fuel reservoir for said fuel and an additive reservoir (4), comprising a chamber formed in a recessed recess (2) in the wall of the fuel reservoir. A method of making such a fuel system.

Description

Internal Combustion Engine Fuel System

technical field

The invention relates to the supply of internal combustion engines using liquid fuels.

In particular the invention relates to a fuel system for such an engine which can be used for an engine supplied with a volatile liquid fuel, and for a fuel such as those sometimes called (depending on the country) diesel or road vehicle diesel heavy liquid fueled engines. The invention also relates to methods of producing such systems.

Background technique

The demand for enhanced environmental protection has led national and international authorities in many regions of the world to strengthen regulatory restrictions on pollutant emissions in many fields, especially in the field of motor vehicle transportation. Therefore, motor vehicle manufacturers have started research efforts aimed at reducing particulate matter emissions (especially for diesel engines) and certain polluting gases (NOx, CO, etc.). These research projects have largely resulted in the addition of specific additives (such as some metal salts, urea, ammonia and carbamates, etc.) to fuel, engine and exhaust gases, etc.

For vehicles powered by diesel engines, motor vehicle manufacturers have provided a solution to the problem of particle emissions by equipping these vehicles with a particle filter placed within the exhaust system that discharges combustion gases into the atmosphere. In order to restore the filtering capacity of these particulate filters, it is necessary to burn off some of the particulate matter that clogs the filter at regular intervals. In order to be able to automate the cyclical cycle for regenerating the particulate filter, it has been necessary to find a way to reduce the combustion temperature of these particulate matter by means of a suitable temporary adjustment of the combustion parameters of the engine itself to a level comparable to that contained in the exhaust gases. The maximum temperature that can be achieved is the same. It has been recognized that the use of a certain amount of chemical combustion additives is necessary so that the combustion temperature of the solid particles in the exhaust gases can be reduced to a level consistent with combustion within the engine and complete elimination of the particles. Liquid additive reservoirs have been devised for mounting on, in or adjacent to a fuel reservoir of a diesel motor vehicle, the liquid additive reservoir having a volume smaller than that of the fuel reservoir.

Thus, patent application DE 10112361 discloses a fuel reservoir in the form of a saddle comprising an additive reservoir placed next to a pump for equalizing the fuel levels in different parts of the reservoir. Such a system is compact, but has the disadvantage that the additive reservoir must be produced separately and then inserted into the fuel reservoir. Furthermore, such systems are limited to additives that must be metered into the fuel storage itself.

Contents of the invention

It is therefore an object of the present invention to provide a compact but versatile fuel system suitable for the production of supply systems for engines working with light, volatile hydrocarbons, and for supply systems for engines working with heavy hydrocarbons The same applies to the production of , and the fuel system enables the metering of additives not only into the fuel reservoir itself, but into any other part of the fuel system, engine or exhaust system etc.

Thus, the invention relates to a fuel system for an internal combustion engine operating on liquid fuel, comprising a fuel reservoir for said fuel, and an additive reservoir comprising a chamber formed in a recess in the wall of the fuel reservoir.

In this statement, a fuel system is an assembly of chambers intended to be incorporated into a motor vehicle or stationary power plant and having the primary function of storing, purging, metering or delivering fuel for supplying a heat engine. A motorized vehicle may be a motor vehicle (such as an automobile, truck, motorcycle, riverboat, ocean liner, or airplane) or a vehicle designed to run on rails (such as a railway locomotive). Stationary power plants may include, for example, motors for power generating equipment or machine tool engines.

Fuels are understood to mean hydrocarbons suitable for supplying internal combustion engines.

The phrase "liquid hydrocarbons" refers to hydrocarbons that exist in the liquid state in the fuel reservoir of the fuel system under normal conditions of engine use.

The phrase "volatile liquid hydrocarbon" refers to a liquid hydrocarbon (according to the definition above) having a saturated vapor pressure greater than 1 bar at 293K (20°C). Volatile liquid hydrocarbons commonly used to supply heat engines of motor vehicles are those sold commercially under the name "gasoline" and are used in so-called "explosive" spark-ignited heat engines Hydride.

The phrase "heavy liquid hydrocarbons" refers to liquid hydrocarbons having a saturated vapor pressure below 1 bar at 293K (20°C). Heavy liquid hydrocarbons commonly used to supply heat engines of motor vehicles are those sold commercially under the name "diesel" and used in compression ignition heat engines operating on the Diesel cycle hydrocarbons.

According to the invention, the additive reservoir is made in one piece with the fuel reservoir. In the following paragraphs, this component is referred to by the generic term "reservoir". The reservoir can be made of any material compatible with each liquid hydrocarbon it may hold. At the same time, the material must be chemically inert to volatile liquid hydrocarbons and heavy liquid hydrocarbons at normal service pressures and temperatures. It can be made of plastic or metal. Within the context of the present invention, plastics can give very good results.

The reservoir can be fabricated by any suitable method. In a preferred embodiment of the invention, the reservoir is manufactured by a molding operation. In this preferred embodiment of the invention, the material of the reservoir must be selected from those which allow its manufacture by moulding. For this purpose, thermoplastic materials are very suitable. Thermoplastic refers to any thermoplastic polymer, including thermoplastic elastomers and mixtures thereof. The term "polymer" refers to homopolymers and copolymers (especially binary or ternary). Non-limiting examples of such copolymers are: random copolymers, alternating copolymers, block copolymers and graft copolymers. Any type of thermoplastic polymer or copolymer having a melting point below the decomposition temperature is suitable. Synthetic thermoplastics whose melting range extends beyond at least 10 degrees Celsius are particularly suitable. As examples of such materials there already exist those having a polydispersity of molecular weights. In particular polyolefins, vinyl polyhalides, thermoplastic polyesters, polyketones, polyamides and copolymers thereof can be used. Mixtures of polymers or copolymers may also be used, as well as mixtures of polymeric materials with inorganic, organic and/or natural fillers such as, but not limited to, carbon, inorganic salts or other derivatives, natural fibers, glass fibers and polymeric fibers. It is also possible to use a multilayer structure consisting of a plurality of superimposed integral layers comprising at least one of the polymers or copolymers described above. Ethylene polyhalides and polyolefins are generally preferred. A frequently used polymer is polyethylene. Excellent results have been achieved using high density polyethylene (HDPE).

The reservoir of the system according to the invention is usually connected with a feed pipe for introducing liquid fuel into the fuel reservoir. The tube may be manufactured separately and then connected to the reservoir by any suitable means, for example by welding or gluing. According to the invention it is preferred that the feed tube is molded in one piece with the reservoir.

According to the invention, the reservoir comprises in its wall a recess which is concave on its face facing the outer side of the reservoir. The shape of the recess is not important for defining the invention. It may equally well have the shape of a curved surface, for example of a sphere or part of an ovoid, of a cone or frustum of a cone, or of a polyhedron. It is preferably given a regular or irregular curved shape.

According to the present invention, a chamber is formed in the recess constituting the main part of the additive reservoir. This chamber is advantageously provided with a metering system preferably comprising injectors connected to injection pumps and present where the additive is to be dosed (reservoir, engine, discharge, etc.). The injector and injection pump can both be placed inside or outside the recess. The metering system preferably comprises a jet pump as described in FR 0320880.8 filed in the applicant's name.

When the additive is to be added to the fuel, the chamber of the additive reservoir communicates with the fuel reservoir through an opening through it. In this way, the chamber preferably comprises a system for metering the additive from the chamber into the reservoir through the aforementioned opening, said metering system advantageously comprising a pump and an injector through the aforementioned opening.

Where the metering system has the function of dispensing additive into the fuel reservoir, it is dispensed in an amount that is a mathematical function (not necessarily but usually a proportional function) of, for example, the instantaneous fuel consumption of the engine. This quantity is usually calculated by a single board computer or a special calculator. As an alternative, the metering can take place immediately after charging, depending on the amount of fuel introduced during the charging process. In this case, a single board computer or computer is advantageously connected to the means for monitoring the opening and closing of the fuel feeding system. This device may comprise an electromagnet connected to the movable part (strictly a stop, or any other closing system, manual or automatic) and changing polarity between open and closed positions. This difference in polarity state is monitored by the single board computer which records the memory capacity as it is informed. If the position of the detent when closed corresponds to the rest position of the single board computer, it is possible to calculate the difference in fuel volume introduced between the moment the system is activated and the moment the system becomes stable again. This volume can be used as a basis for calculating the metering (performed after closing the stop) necessary to maintain a constant additive concentration.

More generally, the aforementioned chamber is intended to serve as a reservoir for any additive, preferably slurry or liquid, which as previously described will be added directly to the fuel, but which may also be introduced into the engine or exhaust gases or the like. In the case of the system according to the invention for use with diesel engines, the additives advantageously comprise carbonaceous solid particles (produced by incomplete combustion of heavy hydrocarbons in compression ignition engines) dissolved in hydrocarbon solvents ) Compositions of low temperature combustion catalysts. Examples of liquid additives suitable for this variant are iron and cerium salts in hydrocarbon solutions.

The chamber of the additive reservoir is advantageously closed by a cover of any shape. Usually, this cover consists of a disc ready to be fixed to the periphery of the recess. The material from which the cover is made is not critical for defining the invention. Indeed, the cover should be made of a material capable of withstanding the chemical and mechanical stresses to which the fuel system of an internal combustion engine is normally subjected during normal use. For example, it can be made of metal or synthetic resin. In the case of a synthetic resin, it is advantageously the same as the synthetic resin of the fuel reservoir. In a variant, the means for metering the additive, such as a jet pump, is secured to the cover and is connected to at least one electrical conductor which passes through the cover in a leak-tight manner. The purpose of this conductor is to power the unit. In the case of a multi-conductor, it is also possible to optionally connect the metering device to an engine management calculator or any other control unit. The lid must seal the chamber. This can be achieved by any suitable means, and can be removable or non-removable. Connection means that can be used in the system according to the invention include welding, gluing and crimping. As a variant, the cap is a circular cap which is screwed onto a threaded annular area of the recess perimeter.

The system according to the invention preferably also comprises feeding means for introducing additives into the chamber. This feed means may comprise a feed tube which may either communicate with or be present within the feed tube of the fuel reservoir, or may be separate from the feed tube of the fuel reservoir. According to an advantageous embodiment of the invention, the feed pipe of the fuel storage and the feed pipe of the additive storage are in communication, and the feed pipe of the additive storage is inside the feed pipe of the fuel storage.

The system according to the invention, in addition to the outlets for guiding the injectors for distributing the fuel, advantageously comprises a pipe for venting the gas of the additive reservoir, which also preferably ends in the feed pipe of the main fuel reservoir . The stoppers commonly used at the ends of the feed and exhaust pipes advantageously keep these pipes closed in a more or less leak-proof manner, except when the additive reservoir is being fed.

In this advantageous form of the additive system according to the invention, the pipe for venting the additive reservoir can be provided in its upper part for visually indicating to the operator at the end of the process of filling up the additive via the feed pipe device in overflow condition. These means may consist, for example, of a float placed in the exhaust pipe, which immediately rises to the upper outlet of the pipe when the reservoir is filled with additive and is about to overflow through this pipe.

Finally, the exhaust pipe according to this variant of the invention is preferably provided with an overpressure and underpressure safety system. The purpose of this system is in particular to be able to remove the gas present in the additive reservoir during the feeding process (overpressure safety) and to replace the volume of additive that is gradually consumed with air during vehicle operation (negative pressure safety). Advantageously, the system includes a valve that opens only above a given pressure threshold (eg above 120 mbar), in order to prevent leakage of additives and ingress of unwanted liquids, dust, etc.

The invention also relates to a method of manufacturing a fuel system as described above, wherein:

- manufacture of a reservoir for said fuel, the walls of which have recesses recessed on their outer face;

- Manufacture of covers;

- sealingly attaching said cover to the periphery of the aforementioned recess forming the chamber;

- introduction of additives into the chamber either before or after attaching the cover; and

- Connecting the chamber to a system for metering the additive before or after the additive is introduced into the chamber.

In this method, the terms used have the same meaning as those used above to describe the fuel system. Preferably, the reservoir and the lid are made of a plastic as previously described, and in a particularly preferred manner of a thermoplastic material, which allows them to be manufactured by moulding. Any type of suitable molding can be used. For the production of reservoirs, inflation extrusion molding and inflation injection molding, and especially inflation extrusion molding, are particularly recommended. For the lid, injection molding is preferred.

Description of drawings

The unique features and details of the present invention will become more apparent from the following description of the accompanying drawings.

Figure 1 (not shown to scale) shows in cross-section the fuel system of an internal combustion engine using heavy hydrocarbons, such as diesel.

Detailed ways

The fuel system shown in Figure 1 is particularly intended for use with vehicles equipped with compression ignition (sometimes referred to as "diesel") internal combustion engines. The fuel system comprises a fuel reservoir made of polyethylene, the wall 1 of which has a recess 2 covered by a disc 3 delimiting a chamber 4 . Chamber 4 serves as a reservoir for liquid additives of heavy hydrocarbons. The additives include catalysts that promote the combustion of carbonaceous particles or dust produced during the combustion of heavy hydrocarbons in the engine compartment. The chamber 4 is connected to the reservoir by a metering system comprising an electro-injection pump 5 attached to the disc 3 and immersed in a liquid additive (not shown). A pipe 6 passes through the disc 3 and connects the pump 5 to an injector 7 which penetrates the wall of the reservoir 1 through an opening (not shown). The pump 5 is supplied with electrical current via electrical conductors 8 which pass through the disc 3 in a leak-tight manner. The tube 9 emerging from the opening (not shown) of the disc 3 acts as a tube for feeding the additive to the chamber 4 . The second pipe 10 is the pipe that vents the additive reservoir when it is fed. Both tubes are normally closed when the internal combustion engine is running.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. In the above-described embodiments, various modifications and changes are possible to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A fuel system for an internal combustion engine operating on liquid fuel and comprising a fuel reservoir for said fuel and an additive reservoir, characterized in that said fuel reservoir and said additive reservoir are manufactured In one piece, the additive reservoir includes a chamber formed in a recess in the fuel reservoir wall. 2. The fuel system of claim 1, wherein the additive is intended to be added to the fuel and the chamber communicates with the fuel reservoir through an opening through the chamber. 3. The fuel system of claim 2, wherein said chamber includes a system for metering said additive from said chamber into said reservoir through said opening, said metering system comprising a pump and injector through the aforementioned opening. 4. The fuel system according to claim 2 or 3, characterized in that the additive is added to the fuel immediately after the fuel reservoir has been charged, the amount being connected to a device capable of monitoring the fuel The opening and closing of the reservoir is calculated by a single-board computer or calculator on the device, and said single-board computer/calculator is able to calculate the volume of fuel introduced during the feeding process, and subsequently meter the volume of said additive. 5. The fuel system of claim 2, wherein: - the fuel is diesel and the engine is a compression ignition engine; and - the additives include dissolved in hydrocarbon solvents, used to promote The catalyst component for the low-temperature combustion of carbonaceous solid particles produced by incomplete combustion of diesel in the engine. 6. The fuel system of claim 1, wherein the chamber is closed by a cover made of the same material as the fuel reservoir. 7. The fuel system of claim 1 , including a tube feeding the additive reservoir, the tube emerging within a tube feeding the fuel reservoir. 8. The fuel system of claim 1 including a tube for venting the additive reservoir, the tube emerging from a tube feeding the fuel reservoir. 9. A method of making a fuel system according to claim 1, wherein: - manufacture of a reservoir for said fuel, said reservoir being made in one piece with a reservoir for additives, said reservoir having a wall with recesses recessed on its outer face; - Manufacture of covers; - sealingly attaching said cover to the periphery of the aforementioned recess in order to form the chamber; - introducing additives into the chamber either before or after attaching the lid; and - before or after introducing said additive into said chamber, said chamber is connected to a system for metering said additive. 10. The method of claim 9, wherein the reservoir and the cap are made of thermoplastic material and the reservoir is manufactured by blown extrusion and the cap is manufactured by injection.

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