Powertrain equipped with a heated fuel rail
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-03-08
- Publication Date
- 2026-08-07
AI Technical Summary
Existing powertrains using liquefied petroleum gas (LPG) face the issue of re-condensation downstream of the steam regulator, leading to uncontrolled liquid fractions in the fuel distribution rail, which results in unpredictable gas injection into combustion chambers.
A heated gas distribution ramp is integrated into the powertrain, heated by a heat transfer fluid pipe, typically water, to maintain gas temperature above the condensation point, preventing liquid droplets from forming and ensuring controlled gas injection.
The solution effectively prevents liquid droplets from entering the combustion chambers, ensuring consistent gas injection and maintaining control over the gas mass flow, without requiring significant structural modifications or increased bulkiness.
Smart Images
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Abstract
Description
Description Title of the invention: Powertrain equipped with a ramp heated fuel
[0001] — The present invention relates to a powertrain equipped with a ramp heated fuel.
[0002] — On internal combustion engines operating on liquefied petroleum gas (or LPG), particularly those used in motor vehicles, poses a risk of re-condensation. gas at the outlet of a vaporizer-regulator associated with the engine.
[0003] — In a manner known per se, LPG is stored in liquid phase within a tank of the vehicle, then it is conveyed in liquid phase to a solenoid valve located in the vehicle's engine compartment, which closes the LPG supply circuit in case of engine cut-off. Then, the still-liquid LPG is routed to the vaporizer- regulator, which serves both to vaporize the liquid LPG into gas and to ensure the regulation of gas pressure.
[0004] — In the classic case of indirect multipoint injection, the gas from the vapor- The regulator then enters a fuel rail of the engine, or dis- rail fuel delivery, which is equipped with a plurality of injectors opening into Intake pipes of a distributor, or intake manifold, of the engine. LPG gas is introduced into the intake pipes of the distributor through the various in- injectors, and it is mixed there with the outside air admitted into the distributor. The air- mixture fuel is then admitted into the engine's combustion chambers to be burned.
[0005] — Alternatively, in the case of direct injection, the gaseous fuel is injected di- directly into the engine's combustion chambers via the injectors.
[0006] The risk of re-condensation is present given that the pressure changes from over 200 bars in a liquefied gas tank, at a pressure of a few bars only at the outlet of the vaporizer and regulator, then in the fuel rail (in the case (as mentioned above regarding indirect injection). This sudden drop in pressure means that the gas intended to be injected into the engine's distributor, before being admitted into the combustion chambers The combustion process of the engine will involve a liquid fraction, which will be introduced into the intake pipes of the distributor with the gaseous fraction, and will tend to Wetting the walls of the distributor. The consequences of such a phenomenon The accumulation of liquid on the walls of the distributor is such that the quantity (flow rate) mass) of gas injected into the combustion chambers is poorly controlled and that the Wealth control then becomes random.
[0007] — To avoid the re-condensation of LPG downstream of the vaporizer, more precisely in the fuel distribution rail, it is necessary to be positioned below the vaporization curve of the gas, which depends on the temperature, pressure and composition of the latter. Publication US548393A discloses a fuel supply module for providing gaseous fuel to an internal combustion engine, which includes a pressure regulator for reducing the gas pressure from a relatively high tank pressure to the relatively low pressure required for introducing the gas into the engine, with a heating chamber that at least partially surrounds the regulator. The fuel supply module only partially addresses the problem addressed by the invention. Publication EP1934467B1 concerns an auxiliary cold-start system preferentially used in internal combustion engines that use alcohol as fuel, but so-called "flex-fuel" engines (alcohol, gasoline, CNG) are also included within the scope of the invention. This system uses resistors positioned at the injector inlets, resistors inside the injectors, or a single resistor for the entire injector nozzle support tubing. In addition, auxiliary injection nozzles, also equipped with resistors, are provided in the engine's intake manifold. Although fuel heating appears sufficient in this case, the need for multiple resistors will result in increased fuel consumption and significant additional costs. A powertrain according to the invention is configured to prevent the formation of a liquid fraction downstream of the vaporizer and more specifically in the fuel distribution rail, while overcoming the disadvantages encountered in existing powertrains. The invention relates to a powertrain comprising an internal combustion engine, a pressurized gas tank and a vaporizer, said powertrain comprising an upstream gas distribution rail to the engine's combustion chambers, said rail being inserted into a gas supply circuit connecting the gas tank and said combustion chambers. According to the invention, a heat transfer fluid circulation tube is in contact with the fuel rail so as to vary the temperature of the gas passing through said rail before said gas is injected into the engine's combustion chambers. In this way, depending on the temperature of the heat transfer fluid circulating in the tube, the temperature of the gas at the tank outlet can either be increased or decreased. Preferably, the temperature of the heat transfer fluid circulating in the tube is raised in order to increase the temperature of the gases circulating in the fuel rail and thus prevent the formation of liquid droplets that would otherwise be suspended. These gases could be routed to the distributor, where they would at least partially stagnate, and therefore not all be admitted into the combustion chambers, with all the problems that this could cause. Advantageously, the heat transfer fluid is a liquid, and preferably this liquid is water. The fluid can be part of either a circuit specifically designed for this function of heating the gases circulating in the rail, or an existing circuit such as the engine cooling circuit. Advantageously, the powertrain has indirect injection, meaning that the gas is not injected directly into the combustion chambers but upstream of intake valves opening into said chambers, into the intake manifolds of a distributor. The gas can, for example, be natural gas, town gas, or liquefied petroleum gas (LPG).The distribution rail can be considered an intake plenum, that is, a volume with a single inlet from the vaporizer and multiple outlets containing injector ports. Each injector opens into a combustion chamber of the engine, specifically into an intake manifold of the distributor which leads to a combustion chamber. Heat transfer between the heat transfer fluid circulation pipe and the rail occurs primarily by thermal conduction. According to one possible feature of the invention, the gas is injected from the rail into intake pipes of an engine distributor serving the combustion chambers. According to one possible feature of the invention, the distribution rail is metallic, the heat transfer fluid circulation pipe is metallic and is brazed to said rail. In this way, the heat exchange between the fluid circulation pipe and the rail occurs primarily by thermal conduction. The fluid circulation pipe can be attached directly to the rail, and the assembly consisting of said pipe and rail is installed in the vehicle. Alternatively, it can be attached after the rail has already been installed in the vehicle. In this latter case, the fluid circulation pipe can be attached to the rail at the last moment, according to the user's requirements. According to one possible feature of the invention, the distribution manifold is elongated, with the heat transfer fluid circulation pipe being wound around said manifold. In this configuration, since the heat transfer fluid circulation pipe surrounds the manifold, the temperature change of the gases circulating in said manifold will be homogeneous and complete, without risk of creating a temperature gradient within said gases. According to one possible feature of the invention, the heat transfer fluid circulation pipe is helical in shape, said pipe having at least two loops continuously extending along the entire length of the distribution manifold. In this way, the temperature change of the gases flowing through the manifold will be effective along its entire length. Preferably, the manifold comprises four loops extending along the entire length of the distribution manifold. Advantageously, each loop completely encircles the manifold, extending over a portion of its length. According to one possible feature of the invention, the distribution manifold has a parallelepiped shape and a square cross-section, said distribution manifold being delimited by an inlet face into which a cylindrical nozzle opens. Preferably, this nozzle extends perpendicularly to the inlet face. This nozzle is intended to receive a conduit from a vaporizer located at the outlet of the gas tank, and constitutes an inlet to the manifold for the gases coming from the tank. According to a possible feature of the invention, the nozzle is straight and opens into a central area of the inlet face so that an axis of revolution of said nozzle is in continuity with a longitudinal and central axis of the distribution ramp. The nozzle is arranged on the ramp so as to be in perfect alignment with said ramp and so as to increase the length of said ramp. According to one possible feature of the invention, the distribution rail comprises several outlet channels, each having a housing for receiving an injector. Advantageously, these outlet channels are parallel to each other and extend perpendicularly to a longitudinal axis of the rail. According to one possible feature of the invention, the gas distribution manifold has a sensor for measuring the temperature and pressure of the gases circulating inside said distribution manifold. The invention also relates to an assembly of a gas distribution ramp and a heat transfer fluid circulation tube for the realization of a powertrain according to the invention. According to the invention, the heat transfer fluid circulation pipe is metallic and the distribution manifold is metallic, the fluid circulation pipe being brazed to the distribution manifold. Preferably, the heat transfer fluid circulation pipe snakes around the manifold. The invention also relates to a vehicle comprising a powertrain according to the invention. According to the invention, the heat transfer fluid circulation pipe is part of an engine cooling circuit. A powertrain according to the invention has the advantage of being able to ensure, safely and reliably, a sufficiently high temperature of the gases passing through the The distribution ramp prevents the formation of liquid droplets that could be injected into the combustion chambers. It also has the advantage of providing this additional functionality without requiring extensive structural modifications and without increasing its size. A detailed description of a preferred embodiment of a powertrain according to the invention is given below, with reference to the following figures: [Fig.1] Fig.1 is a perspective view of a ramp and a circulatory pipe for a heat transfer fluid of a powertrain according to the invention. The principle of a powertrain according to the invention is to include a heated distribution rail 1, designed to heat a gas at the outlet of a vaporizer that vaporizes the gas from a storage tank, before it is injected into the combustion chambers of an internal combustion engine, in particular into the intake manifolds of an engine air distributor supplying the combustion chambers in the case of indirect injection, or alternatively directly into the combustion chambers. Such a heated rail 1 can be integrated into a powertrain having an internal combustion engine with a fuel to be heated by indirect injection, such as natural gas, town gas, or LPG. A powertrain according to the invention comprises an internal combustion engine, a liquid-phase gas storage tank, which could, for example, contain LPG essentially composed of a mixture of butane and propane, and a pressure regulator for vaporizing the gas from the tank. In such powertrains, there is a risk of gas re-condensation at the outlet of the pressure regulator, and more specifically in a fuel distribution manifold located at the outlet of said pressure regulator, to which the gas, theoretically in a purely gaseous phase, is routed. In this case, a gaseous mixture containing a liquid fraction is injected into the engine's combustion chambers, particularly into the intake manifolds of an engine distributor serving said combustion chambers. This mixture will wet the walls of the distributor's intake manifolds and at least partially prevent the liquid from entering said chambers.The consequence of such an injection is that the quantity of gas injected is not well controlled and the fuel mixture control becomes random. To prevent the formation of this liquid fraction, a powertrain according to the invention incorporates a heated gas distribution rail 1, said rail 1 being located on the gas circuit between the pressure regulator at the outlet of the gas tank and the engine's combustion chambers, and more specifically, in the case of indirect injection, between the pressure regulator and a distributor upstream of said combustion chambers. The purpose of this heated rail 1 is to warm The gases pass through this rail, thus preventing the formation of liquid droplets upstream of the engine's combustion chambers. Such a rail therefore allows for the injection of only gas, directly into these chambers, specifically into an engine distributor in the case of indirect injection.Referring to [Fig. 1], the heating element 1 has an elongated, parallelepiped-shaped hollow body 2, said body 2 having a square cross-section. This hollow body 2 is delimited by an inlet face 3 and an outlet face, each square, said two faces 3 representing the two ends of said hollow body 2 considered along a longitudinal axis thereof. The heating element 1 has a straight, cylindrical end 4 opening into a central area of the inlet face 3 of the hollow body 2. In this way, the axis of revolution of this end 4 coincides with a longitudinal and central axis of the hollow body 2. The end 4 extends the hollow body 2 to increase its length. This end 4 has a collar 5 in the form of an annular ridge that locally increases the outer diameter of said end 4.This fitting 4 is designed to receive a cylindrical conduit from a vaporizer located at the outlet of a gas tank, said conduit being press-fitted around this straight fitting 4. This manifold 1 advantageously has three gas outlet channels 6, 7, 8, said channels being parallel to each other and extending perpendicularly to a longitudinal axis of the hollow body 2 of the manifold. Each of these outlet channels 6, 7, 8 has a recess 9 opening into said outlet channel 6, 7, 8, and is designed to house an injector (not visible in the figure). Of the three outlet channels 6, 7, 8, two channels 6, 8 are located near the two end faces 3 of the hollow body 2 of the manifold 1, and a third channel 7 is located centrally on said hollow body 2, equidistant from the other two outlet channels 6, 8.A pressure and temperature sensor 9 is placed on the hollow body 2 of the rail 1, said sensor 9 opening into the hollow body 2 to measure the pressure and temperature of the gases passing through the rail 1. It should be noted that the rail 1 is made of metal. A heat transfer fluid circulation tube 10, made of metal, is brazed to the hollow body 2 of the rail 1 in order to preheat the gases from the reservoir before they are redirected to the engine's combustion chambers via the outlet channels 6, 7, 8 of said rail 1. This tube 10 is preferably cylindrical and has a constant internal diameter. Advantageously, this tube 10 is helical in shape and winds around the hollow body 2 of the rail 1. It may, for example, have four continuous loops 11, 12, 13, 14, extending along the entire length of the hollow body 2 of the rail 1. In other words, each loop completely surrounds the hollow body 2 of the rail 1, extending over a portion of the rail 1's length. In this way, by surrounding the hollow body 2 of the rail 1, The heat transfer fluid circulation pipe 10 will heat the gases circulating in the rail 1 homogeneously and completely, preventing the establishment of a temperature gradient in said gases. The heat transfer fluid can, for example, be water, which would come from an engine cooling circuit, in which case the pipe 10 would be an integral part of said cooling circuit. The temperature of the water circulating in the pipe 10 can, for example, be between 30°C and 80°C. Thus, thanks to the presence of the water circulation tube 10 fixed around the hollow body of the fuel rail 1, the gases circulating in said fuel rail 1 will be sufficiently heated to prevent the formation of liquid droplets, which could penetrate the intake manifolds of an engine distributor and accumulate on their walls (this is referred to as "wall wetting"). Only gases free of liquid droplets will enter the intake manifolds, and then fully into the combustion chambers, thanks to the presence of this heated fuel rail 1. The injection system of a powertrain according to the invention is indirect. The heating of the gases is very rapid, on the order of a few seconds. It should be noted that the water circulation pipe 10 can take on a variety of shapes, the essential point being that it is in contact with the hollow body 2 of the ramp 1 in order to reheat, essentially by thermal conduction, the gases circulating in said ramp.
Claims
Demands
1. Powertrain comprising an internal combustion engine, a pressurized gas tank and a vaporizer-regulator, said motor- propellant comprising an upstream gas distribution ramp (1) towards of the engine combustion chambers, said ramp (1) being inserted in a gas supply circuit connecting the gas tank and said combustion chambers, characterized in that a tube (10) the circulation of a heat transfer fluid is in contact with the ramp (1) of in order to vary the temperature of the gas passing through said ramp (1) before the said gas is injected into the combustion chambers of the engine.
2. Powertrain according to claim 1, characterized in that The gas is injected from the rail (1) into the intake pipes of an engine distributor serving the combustion chambers.
3. Powertrain according to claim 1 or 2, characterized in that that the distribution ramp (1) is metallic, and in that the tubing (10) The heat transfer fluid circulation system is metallic and is brazed to said ramp (1).
4. Powertrain according to any one of claims 1 to 3, characterized in that the distribution ramp (1) is elongated, and in that that the heat transfer fluid circulation pipe (10) is coiled around said ramp (1).
5. Powertrain according to claim 4, characterized in that the heat transfer fluid circulation pipe (10) is of helical shape licorice-shaped, and in that it has at least two loops (11, 12, 13, 14) continuously extending along the entire length of the ramp (1) of dis- tribute.
6. Powertrain according to any one of claims 1 to 5, characterized in that the distribution ramp (1) has a shape parallelepiped and has a square cross-section and in that said distribution ramp (1) is delimited by a face inlet (3) into which a cylindrical nozzle (4) opens.
7. Powertrain according to claim 6, characterized in that the tip (4) is straight and opens into a central area of the face input (3) so that an axis of revolution of said end piece (4) is in the continuity of a longitudinal and central axis of the ramp (1) of dis- tribute.
8. Powertrain according to any one of claims 1 to '7, characterized in that the distribution ramp (1) comprises several output channels (6, 7, 8) each having a housing (9) intended for to receive an injector.
9. Powertrain according to any one of claims 1 to 8, characterized in that the gas distribution ramp (1) has a gas temperature and pressure measurement sensor (9) circulating within said distribution ramp (1).
10. Assembly of a gas distribution ramp (1) and a pipe (10) circulation of a heat transfer fluid for the construction of a group powertrain according to any one of claims 3 to 9, ca- characterized in that the tubing (10) for circulating the heat transfer fluid is metallic and the distribution ramp (1) is metallic, and in that the heat transfer fluid circulation pipe (10) is brazed to the ramp (1) of distribution.
11. | Vehicle comprising a powertrain conforming to one any of the claims | to 9, characterized in that the tubing (10) circulation of heat transfer fluid is part of a cooling circuit engine dismantling.