Powertrain equipped with an optimized LPG gas injection system.

Abstract

The invention relates to a powertrain (1) with indirect LPG injection, comprising a cylinder crankcase (2) on which a cylinder head (3) is mounted, which cylinder head comprises at least two intake pipes (4) each leading into a cylinder (8), the powertrain comprising at least two LPG intake manifolds which lead into the intake pipes (4). According to the invention, a free end of each intake manifold (25, 26, 27, 28, 29) via which the LPG is released is placed in the injection pipe (4), and the free end comprises a dispersion device (30, 35, 39) for releasing LPG over a wider area of the intake pipe (4), the dimensions of which are greater than those of a cross-section of the intake manifold (25, 26, 27, 28, 29).

Description

1 / 13 “POWERTRAIN EQUIPPED WITH AN OPTIMIZED LPG GAS INJECTION SYSTEM”

[001] The present invention relates to a powertrain equipped with an optimized LPG (LPG stands for Liquefied Petroleum Gas) injection system.

[002] More specifically, the invention relates to a vehicle powertrain with indirect LPG injection, which may notably comprise a supercharged spark-ignition engine, or alternatively, a naturally aspirated type. This powertrain comprises a cylinder block in which a cylinder head is mounted, in which air intake ducts have been formed that open into the cylinders. The cylinder head has a face called "intake", against which an intake manifold is fixed, suitable for directing the intake air and / or gases towards the intake ducts formed in the cylinder head and connected to the cylinders, and a face called "exhaust", against which an exhaust manifold is fixed to recover the burnt gases resulting from combustion in the engine cylinders.The air and / or intake gases are directed to the intake manifold, having been previously compressed by passing through a compressor, which may, for example, constitute a compression stage of a turbocharger, in the case of a supercharged engine.

[003] To improve the efficiency and performance of the powertrain, the intake compressed air is cooled before it enters the engine cylinders. Thus, a cooling stage is installed in the intake air circuit upstream of the cylinder head, considering the direction of intake air circulation. This cooling stage comprises, for example, a W-CAC (Water Charged Air Cooler) type air / water heat exchanger, through which the hot compressed air transfers some of its heat to the water or to a coolant. Petition 870250080603, dated 08 / 09 / 2025, page 10 / 30 2 / 13 This heat exchanger is housed in a casing that extends downstream through a mounting flange, taking into account the direction of intake air circulation, forming a chamber with, for example, a cylinder head recess. Said chamber forms an intake manifold plenum.

[004] Powertrains with indirect LPG injection include an LPG intake duct in the air intake circuit. Injection is generally performed upstream of the engine cylinders, in air intake ducts formed in the cylinder head. Thus, LPG injection tubes are drilled from an intake face of the cylinder head to open obliquely into an air intake channel. The LPG is then mixed with the intake air before its introduction into the cylinders, which is controlled by intake valves. Each cylinder is bounded by a cylindrical side wall, a piston, and a cylinder head bottom wall.

[005] Publication FR-A1-3112575 discloses a gas injection rail carrying at least one tubular metal sleeve suitable for housing and supplying fuel to a fuel injector, more particularly a fuel of the LPG gas type. The liquid gas is contained in a tank and carried to a pressure regulator. It is then transported to the engine intake via the injection rail connected to the injectors, each of which has an injection end that opens onto an intake air channel formed in a cylinder head of a thermal engine. However, this injection end was not specifically designed to accurately guide the LPG gas into the intake ducts formed in the cylinder head.

[006] A powertrain according to the invention has an indirect LPG gas injection system in the intake ducts located upstream of the cylinders, comprising a well-controlled orientation. Petition 870250080603, dated 08 / 09 / 2025, page 11 / 30 3 / 13

[007] The subject of the invention is a powertrain with indirect LPG injection, comprising a cylinder block in which a cylinder head is mounted, wherein said cylinder head comprises at least two intake ducts, each opening to a cylinder and intended to supply said cylinders with LPG, an intake manifold placed against the cylinder block upstream of said intake ducts and an LPG supply circuit comprising a rail fitted with at least two injectors, each extending through a tube fixed to the intake manifold and opening to an intake duct.

[008] According to the invention, a free end of each tube through which LPG gas is emitted is placed in the intake duct, wherein said free end comprises a dispersion device that allows the emission of LPG gas over an enlarged area of ​​the intake duct, whose dimensions are larger than those of a cross-section of the tube. Such a dispersion device aims to eliminate certain angular dispersions related both to the structure of the tube and to its mounting in the intake manifold. Generally, these tubes are bent and therefore prone to emitting LPG gas into the intake ducts with a certain dispersion. The LPG gas emitted by the tubes no longer exits in the form of a directional jet, but rather in the form of a dispersed and therefore enlarged jet, allowing for the homogenization of the spatial distribution of the LPG gas flow in the intake duct.Thanks to this dispersion device placed at the end of each tube, the LPG gas will enter the cylinder more efficiently, in order to improve the efficiency and performance of the powertrain. A powertrain according to the invention comprises an intake air line that may include a compressor and a device for cooling the compressed air. The intake manifold allows directing the compressed and cooled air to the powertrain cylinders through the intake ducts. The LPG gas is injected into the intake ducts at the same time as the air and comes from a gas circuit that runs parallel to the air circuit passing through the supply ducts. The tubes are rigid and... Petition 870250080603, dated 09 / 08 / 2025, p. 12 / 30 4 / 13 preferably made of steel. The passage of the air / LPG gas mixture in each cylinder is controlled by at least one intake valve.

[009] According to a particularly advantageous feature of the invention, each intake duct terminates with two distinct and separate intake subducts, the free end of each tube being placed in the intake duct in a zone located upstream of the two intake subducts and in a central zone of the intake duct, so that the dispersion device can supply LPG gas to both intake subducts. This dispersion device, placed at the free end of the tube, allows LPG gas to be emitted homogeneously towards the two intake subducts, thus preventing the accumulation of LPG gas in one of the two intake subducts, with the greater risk of a possible backflow of LPG gas into the intake duct.

[010] According to a possible feature of the invention, the dispersion device is a part attached to the free end of each pipe and comprising a main channel and two secondary channels in fluidic communication with said main channel, each intended to supply LPG gas into a specific intake subduct. The main channel is intended to extend the pipe, and the two secondary channels branch off from said main channel and are oriented so as to homogeneously supply the two subducts. The part comprising the main channel and the two secondary channels acts as a relay part, enabling the guidance and direction of the LPG gas flow emitted by the pipe without affecting the gas flow rate. The two secondary channels may be curved or straight. They may also have the same cross-section or different cross-sections. Preferably, the main channel and the two secondary channels are cylindrical. They may: • or be materialized by distinct subtubes emerging from the tube, Petition 870250080603, dated 08 / 09 / 2025, page 13 / 30 5 / 13 • or be excavated in a solid part, in which case said part is comparable to an LPG gas distribution nozzle.

[011] According to a possible feature of the invention, the main channel is placed in continuity with the pipe and the two secondary channels originate from said main channel while being oriented towards the two subducts of the intake duct. The main channel is located upstream of the two secondary channels, the term “upstream” being used in relation to the direction of LPG gas flow in the pipe. In other words, the LPG gas passes first through the main channel before passing to the two secondary channels. The gas flow that reaches the main channel is then divided into two distinct flows due to the presence of the two secondary channels.

[012] According to a possible feature of the invention, the two secondary channels extend from the main channel while diverging from each other. In this way, the two secondary channels are not parallel and each is directed towards a specific intake subduct. In other words, one secondary channel is oriented towards one intake subduct and the other secondary channel is oriented towards the other intake subduct.

[013] According to a possible feature of the invention, the two secondary channels form an angle between them that is between 30° and 70°. This angle depends in particular on the positioning of the two intake subducts in relation to each other.

[014] According to a possible feature of the invention, the two secondary channels form an angle of 50° with each other.

[015] According to a possible feature of the invention, the two secondary channels each have a constant cross-section, but different from the cross-section of the other secondary channel.

[016] According to a possible feature of the invention, each tube has a straight segment at the end of which the dispersion device is attached, with Petition 870250080603, dated 08 / 09 / 2025, page 14 / 30 6 / 13 length between 5 mm and 15 mm. This straight segment allows for the homogenization of the gas flow in the tube, immediately before its entry into the main channel, and then its separation into two gas flows due to the presence of the two secondary channels of the dispersion device.

[017] According to an alternative embodiment of a powertrain according to the invention, the dispersion device consists of a conical-ended segment whose intake end has the same dimensions as those of the cross-section of the free end of the tube, and whose exhaust end has at least one dimension larger than those of said intake end, wherein the intake end makes it possible to connect the conical-ended segment to the tube. Thus, for example, assuming that the intake end has a circular shape, the exhaust end may, for example, have an oblong shape, with a major axis greater than the diameter of the intake end and a minor axis less than or equal to said diameter. The exhaust end of the conical segment may assume any shape, the essential point being that it can promote the dispersion of LPG gas in a given direction and over an enlarged area.

[018] A powertrain according to the invention has the advantage of being more efficient and having better performance than existing powertrains, thanks to a judicious addition of a dispersion device at the free end of the LPG gas feed pipes of the intake air ducts of said powertrain. It also has the advantage of providing additional functionality through the presence of these dispersion devices, while maintaining an overall size equal to that of existing powertrains. Finally, it has the advantage of being easily adaptable to various versions, thanks to a simple structural readjustment of the LPG gas dispersion device located at the end of the pipe. Petition 870250080603, dated 08 / 09 / 2025, page 15 / 30 7 / 13

[019] A detailed description of three preferred embodiments of a powertrain according to the invention is provided below, with reference to the following figures:

[020] Figure 1 is a side view of a part of a power train according to the prior art.

[021] Figure 2 is a perspective view of a power train according to the prior art.

[022] Figure 3 is a side view of a prior art powertrain area, including a device for cooling the intake air.

[023] Figure 4 is a perspective view of an area of ​​a powertrain according to the prior art, showing LPG gas feed pipes.

[024] Figure 5 is a side view of an intake duct of a power train according to the prior art, showing the angular dispersion in a first direction of the LPG gas emitted by a feed pipe.

[025] Figure 6 is a top view of the intake duct of Figure 5, showing the angular dispersion in a second direction of the LPG gas emitted by a supply pipe.

[026] Figure 7 is a side view of an LPG gas feed pipe of a first embodiment of a power train according to the invention.

[027] Figure 8 is a front view of the LPG gas supply pipe of Figure 7.

[028] Figure 9 is a perspective view of an area of ​​the first embodiment of a powertrain according to the invention, showing the positioning of the LPG gas supply pipes.

[029] Figure 10 is a sectional view of the end of an LPG gas feed pipe of a second embodiment of a power train according to the invention. Petition 870250080603, dated 08 / 09 / 2025, page 16 / 30 8 / 13

[030] Figure 11 is a perspective view of an LPG gas feed pipe of a third embodiment of a power train according to the invention.

[031] A powertrain (1) according to the invention is preferably a powertrain with indirect LPG injection. In the non-limiting example illustrated by the figures, it is assumed that the powertrain (1) comprises three cylinders (8), of the supercharged type, for example, by a turbocharger. However, it can also be a naturally aspirated type engine.

[032] Referring to Figures 1, 2 and 3, a powertrain (1) according to the invention comprises a cylinder block (2) in which a cylinder head (3) is mounted, in which intake ducts (4) have been formed. The cylinder head (3) has: - an intake face (5) against which an intake manifold (6) is fixed, suitable for directing air and / or LPG gas towards the intake ducts (4) and - an exhaust face (7) against which an exhaust manifold (not visible in the figures) is fixed, for recovery of the burnt gases resulting from combustion in the cylinders (8) of the power train.

[033] The air and / or intake gases from a powertrain intake circuit (1) are directed to the intake manifold (6), having been previously compressed by means of a compressor, which may constitute, for example, the compression stage of a turbocharger.

[034] Referring to Figure 3, to improve the efficiency and performance of the powertrain (1), the intake air is cooled after being compressed by the compressor, and before its admission into the three cylinders (8) of the powertrain (1). Thus, a cooling stage (9) is placed in the intake air circuit, upstream of the cylinder head (3) according to the direction of intake air circulation. This cooling stage (9) comprises, for example, a heat exchanger. Petition 870250080603, dated 08 / 09 / 2025, page 17 / 30 9 / 13 air / water type W-CAC (Water Charged Air Cooler), through which hot compressed air transfers part of its heat to water or a coolant. The heat exchanger is housed in a casing (10), which is extended downstream by a mounting flange according to the direction of intake air circulation, forming a chamber with, for example, a cylinder head recess (3). This chamber forms an intake manifold plenum.

[035] The powertrains (1) with indirect LPG injection comprise an LPG gas supply circuit that opens into the intake ducts (4) of the cylinder head (3), so as to allow said LPG gas to mix with air before said mixture enters the three cylinders (8).

[036] Referring to Figures 2 and 4, a powertrain LPG gas supply circuit according to the prior art schematically comprises a distribution rail (11) that is supplied with LPG gas from a tank, and on which three injectors (12, 13, 14) are fixed, each extended by a feed pipe (15, 16, 17). These three feed pipes (15, 16, 17) are supported by an upper edge (18) of the intake manifold (6). In this way, the LPG gas stored in the tank first passes through the distribution rail (11) before passing through the three injectors (12, 13, 14), then through the three feed pipes (15, 16, 17). These feed pipes (15, 16, 17) are represented as rigid cylindrical tubes, with a constant cross-section throughout their length.

[037] Referring to Figures 4 and 5, the feed tubes (15, 16, 17) each open into an upstream zone (48) of an intake duct (4). Each feed tube (15, 16, 17) is curved and terminates with a straight segment (19) that is inclined relative to a longitudinal axis of the intake duct (4). This straight segment (19) allows said feed tube (15, 16, 17) to inject LPG gas into the upstream area (48) of the intake duct (4), in the same direction as the air passing through said duct. Petition 870250080603, dated 09 / 08 / 2025, p. 18 / 30 10 / 13 intake duct (15, 16, 17), but at an angle to it. In this way, a mixture of air and LPG gas will enter each cylinder (8) of the powertrain (1).

[038] Referring to Figure 6, the upstream zone (48) of each intake duct (4) is extended by two separate and substantially parallel intake subducts (20, 21), the two subducts (20, 21) opening into the corresponding cylinder (8) of the powertrain (1). Each of the two intake subducts (20, 21) has a smaller cross-section than the upstream zone (48), and the cross-sections of the two subducts (20, 21) may be the same or different within the same intake duct (4).

[039] Referring to Figures 1 and 6, several channels (22) are formed in the cylinder head (3) so as to open each at one end of an intake subduct (20, 21) of each intake duct (4). These channels (22) are designed to each receive an intake valve (23, 24) intended to regulate the passage of the air and LPG gas mixture circulating in the intake ducts (4) towards the corresponding cylinder (8). These intake valves (23, 24) are controlled in such a way that they can only occupy two positions: a closed position in which they prevent the passage of the air and gas mixture towards the cylinder in question (8), and an open position in which they allow the passage of said mixture. Thus, as illustrated in Figure 6, the ends of the two intake subducts (20, 21) of each intake duct (4) are each traversed by an intake valve (23, 24).

[040] Referring to Figures 5 and 6, the existing feed pipes (15, 16, 17) have the disadvantage of inducing significant angular dispersions of the LPG gas emitted by them, such dispersions being mainly due to their structure and their attachment to the upper edge (18) of the intake manifold (6). This angular dispersion can reach a range of plus or minus 7°, both in the vertical plane, as illustrated in Figure 5, and in the horizontal plane, as illustrated in Figure 6. Petition 870250080603, dated 08 / 09 / 2025, page 19 / 30 11 / 13 Such angular dispersion cannot be tolerated, as it can lead to the formation of accumulation zones of the air / LPG gas mixture in the upstream zones (48) of the intake ducts (4), which can cause backflow of said mixture towards the intake manifold (6).

[041] To better control the emission conditions of LPG gas in the exhaust of the feed pipes (15, 16, 17), a power train according to the invention comprises feed pipes (25, 26, 27, 28, 29), each ending with a dispersion device that allows LPG gas to be emitted to an enlarged area of ​​the intake duct (4).

[042] Referring to Figures 7, 8 and 9, according to a first embodiment of a power train according to the invention, the dispersion device takes the form of a nozzle (30) comprising a main central channel (31) and two secondary channels (32, 33) extending said main central channel (31). With respect to the direction of flow of the LPG gas in the feed pipes (25, 26, 27), the two secondary channels (32, 33) are placed downstream of the main central channel (31) and originate from said main central channel (31), diverging from each other. The main central channel (31) and the two secondary channels (32, 33) are straight, and preferably the two secondary channels (32, 33) form an angle of 50° with each other.This nozzle (30) is mounted on a straight-ended segment (34) of each feed pipe (25, 26, 27) so that the main central channel (31) is in perfect continuity with this straight-ended segment (34), and so that the two diverging secondary channels (32, 33) are inclined in relation to said straight-ended segment (34). Once the nozzle (30) is mounted on the feed pipe (25, 26, 27), it allows LPG gas to be emitted to the upstream areas (48) of the intake ducts (4) in two different directions forming an angle of 50° between them.

[043] Referring to Figure 10, according to a second embodiment of a power train according to the invention, the dispersion device takes the form of a nozzle (35) consisting of a solid and compact part in which were Petition 870250080603, dated 09 / 08 / 2025, p. 20 / 30 12 / 13 forming a main central channel (36) and two secondary channels (37, 38) that extend said main central channel (36). In relation to the direction of LPG gas flow in the feed pipes (28), the two secondary channels (37, 38) are placed downstream of the main central channel (36) and originate from said main central channel (36), although diverging from each other. The main central channel (36) and the two secondary channels (37, 38) are straight, and preferably the two secondary channels (37, 38) form an angle of 50° between them. This nozzle (35) is mounted on the feed pipe (28) so that the main central channel (36) is in perfect continuity with said feed pipe (28), and so that the two diverging secondary channels (37, 38) are inclined in relation to said feed pipe (28).Once the nozzle (35) is fitted to the feed pipe (28), it allows the LPG gas to be released into the upstream zones (48) of the intake ducts (4) in two different directions forming an angle of 50° between them.

[044] Referring to Figure 11, according to a third embodiment of a powertrain according to the invention, the dispersion device takes the form of a conical end segment (39) of the feed tube (29). This end segment (39) has an intake end (40) with the same dimensions as those of the cross-section of the feed tube (29), and an exhaust end (41) with at least one dimension that is larger than those of said intake end (40). The intake end (40) is placed upstream of the exhaust end (41) and allows the conical end segment (39) to be connected to the feed tube (29). Thus, by way of example, assuming that the intake end (40) has a circular shape, the exhaust end (41) may, for example, have an oblong shape, with a major axis greater than the diameter of the intake end (40) and a minor axis less than or equal to said diameter.The exhaust end (41) of the tapered end socket (39) may. Petition 870250080603, dated 09 / 08 / 2025, p. 21 / 30 13 / 13 assume any shape, the essential point being that it can promote the dispersion of LPG gas in the corresponding intake duct (4).

[045] The dispersion device (30, 35, 39) placed at the end of each feed pipe (25, 26, 27, 28, 29) allows for better distribution of the LPG gas in each intake duct (4) so ​​that it can supply both sub-ducts (20, 21) uniformly. This prevents the formation of LPG gas accumulation zones in the upstream zone (48) of the intake duct (4), which could lead to a backflow of the air / LPG gas mixture into said intake duct (4). Petition 870250080603, dated 09 / 08 / 2025, p. 22 / 30

Claims

1 / 3 CLAIMS 1. Powertrain (1) with indirect LPG injection CHARACTERIZED in that it comprises a cylinder block (2) in which a cylinder head (3) is mounted with at least two intake ducts (4), each opening to a cylinder (8) and intended to supply said cylinders (8) with LPG, an intake manifold (6) placed against the cylinder block (2) upstream of said intake ducts (4), and an LPG supply circuit comprising a rail (11) fitted with at least two injectors (12, 13, 14), each extending through a supply tube (15, 16, 17, 25, 26, 27, 28, 29) fixed to the intake manifold (6) and opening to an intake duct (4), wherein one free end of each supply tube (25, 26, 27, 28, 29) through which the LPG gas is emitted to be placed in the intake duct (4), and wherein said free end comprises a dispersion device (30, 35,39) allowing the emission of LPG gas over an enlarged area of ​​the intake duct (4), whose dimensions are larger than those of a cross-section of the feed pipe (25, 26, 27, 28, 29).

2. Powertrain, according to claim 1, CHARACTERIZED in that each intake duct (4) terminates in two distinct and separate intake subducts (20, 21), and that the free end of each feed tube (25, 26, 27, 28, 29) is placed in the intake duct (4) in a zone (48) located upstream of said two intake subducts (20, 21) and in a central zone of said intake duct (4) so ​​that the dispersion device (30, 35, 39) can feed said two intake subducts (20, 21) with LPG gas.

3. Powertrain, according to claim 2, CHARACTERIZED in that the dispersion device (30, 35) is a part fixed to the free end of each feed tube (25, 26, 27, 28) and comprises a main channel (31, 36) and two secondary channels (32, 33, 37, 38) in fluid communication with said Petition 870250080603, dated 08 / 09 / 2025, page 23 / 30 2 / 3 main channel (31, 36), said secondary channels (32, 33, 37, 38) each being intended to feed a specific intake subduct (20, 21) with LPG gas.

4. Powertrain, according to claim 3, CHARACTERIZED in that the main channel (31, 36) is arranged in continuity with the feed tube (25, 26, 27, 28) and the two secondary channels (32, 33, 37, 38) originate from said main channel (31, 36) and are oriented towards the two intake subducts (20, 21) of the intake duct (4).

5. Powertrain according to claim 4, CHARACTERIZED in that the two secondary channels (32, 33, 37, 38) extend from the main channel (31, 36) while diverging from each other.

6. Powertrain, according to claim 5, CHARACTERIZED in that the two secondary channels (32, 33, 37, 38) form an angle between them that is between 30° and 70°.

7. Powertrain, according to claim 6, CHARACTERIZED in that the two secondary channels (32, 33, 37, 38) form an angle of 50° between them.

8. Powertrain, according to any one of claims 3 to 7, CHARACTERIZED in that the two secondary channels (32, 33, 37, 38) each have a constant cross-section, but that cross-section is different from the cross-section of the other secondary channel (32, 33, 37, 38).

9. Power train, according to any one of claims 3 to 8, CHARACTERIZED in that each feed tube (25, 26, 27, 28) has a straight segment (34) at the end of which the dispersion device (30, 35) is fixed, and that the length of this straight segment (34) is between 5 mm and 15 mm.

10. Powertrain, according to claim 1, CHARACTERIZED in that the dispersion device consists of a final conical segment (39), Petition 870250080603, dated 08 / 09 / 2025, page 24 / 30 3 / 3 wherein an intake end (40) has the same dimensions as the cross-section of the feed pipe (25, 26, 27, 28), and an exhaust end (41) has at least one dimension larger than said intake end (40), and that the intake end (40) allows the final conical segment (39) to be connected to the feed pipe (25, 26, 27, 28). Petition 870250080603, dated 08 / 09 / 2025, page 25 / 30

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