Hydrogen-powered internal combustion engine

Description

Title Hydrogen-powered internal combustion engine DESCRIPTION of the industrial invention entitled: “Hydrogen-powered internal combustion engine” by: Stellantis Europe SpA, Italian nationality, Corso Giovanni Agnelli 200, 10135 Turin Designated Inventors: BAGNATO Massimiliano; MAGHINI Paolo Maria. Filed on: **** DESCRIPTION TEXT Field of invention This invention relates to hydrogen-fueled internal combustion engines. Specifically, the invention was developed with reference to hydrogen-fueled spark-ignition internal combustion engines, whose architecture is derived from a diesel-fueled compression-ignition internal combustion engine. Known technique The current trend toward massively reducing carbon dioxide emissions is impacting the automotive industry at various levels and requires each of these levels to adopt solutions—previously not generally implemented—in order to comply with increasingly stringent regulations at both the national and EU levels. The proposed reduction in carbon dioxide emissions, ultimately leading to their total elimination, requires, among other things, the use of combustion-free vehicle systems (such as those used in electric vehicles) or the use of carbon-free fuels, such as hydrogen. Among the salient characteristics of hydrogen combustion are very high resistance to detonation and a much higher flame front velocity than that of carbon-containing fuels. These characteristics lead to high peak pressure during combustion and therefore require a powerplant structure capable of withstanding the resulting mechanical stresses. -1 The construction of hydrogen engines using architectures derived from diesel cycle engines, or in general from compression ignition engines, is particularly advantageous since these engines are generally sized to withstand higher mechanical stresses than their counterparts with spark ignition, thus allowing for maximizing thermodynamic efficiency during hydrogen combustion. On the other hand, the increasingly stringent emissions regulations (e.g. NOx) that must be complied with during the type approval of vehicles equipped with internal combustion engines increasingly lead to the side effect of an increase in the size of the exhaust gas after-treatment system and, in general, in the equipment of accessories and sensors on board the engine. The technical problem in question is further exacerbated by the upcoming introduction of the Euro 7 standard regarding emissions thresholds for combustion products and noise. The immediate consequence of this is the ever-decreasing space available to accommodate and secure engine components, even essential ones, within the engine compartment. Installing an oil heater in the engine's oil pan is a well-known practice that offers several advantages, especially in cold weather conditions. When temperatures are extremely low, oil tends to thicken, increasing its viscosity. This makes it more difficult to pump oil through the engine and can cause lubrication problems during cold starts. During cold starts, it is essential that the oil quickly reaches all moving parts of the engine to avoid wear due to lack of lubrication. Furthermore, low-temperature oil not only reduces lubrication but also increases the engine's internal resistance. This translates into more energy needed to start and run the engine, reducing overall efficiency and increasing pollutants, especially during the first few minutes of operation. An oil heater helps reduce this cold-running period, improving combustion and reducing polluting emissions. An oil heater is typically a resistive electric heating element inserted into the oil pan. When energized, this element converts electrical energy into heat, which is transferred to the surrounding oil. Installing an electric heater in an engine's oil pan presents some challenges, particularly regarding external connections for electrical wiring. Running electrical wiring through the oil pan wall creates holes that must be properly sealed. If the gaskets are not properly installed or deteriorate over time, oil leaks can occur, compromising engine lubrication and potentially causing damage. Furthermore, these additional holes in the oil pan for external electrical connections represent a potential entry point for water, dust, and other contaminants. This can damage the heater and compromise oil quality. Additionally, external connections and the heater itself must be accessible for maintenance. This may require modifications to the oil pan or vehicle design, making both maintenance and the engine design more complex and costly. Installing a heater and its wiring could interfere with other engine or vehicle components, and installing the heater and external connections can be complicated and require special tools, increasing installation costs and time. In the case of a hydrogen engine adapted from a diesel-fueled compression-ignition internal combustion engine, there is a need for a reliable, easy-to-install electric resistive heating element installed in the oil sump that does not require redesigning the oil sump. However, this requirement faces the aforementioned challenges related to the ever-decreasing space available for engine components within the engine compartment. -3Summary of the invention The aim of the present invention is to solve the above problem in an efficient, economical and space-saving manner compatible with the equipment dimensions of the hydrogen engine derived from a diesel engine, ensuring excellent reliability and ease of installation and maintenance. According to the present invention, this object is achieved, in accordance with claim 1, by the fact that the engine includes a resistive electrical heating element inside the oil pan wherein the resistive electrical heating element has an elongated shape and has one end corresponding to an oil outlet hole provided in the pan. In a preferred embodiment according to the invention, the resistive electric heating element is formed integrally with the closing cap of the oil outlet hole. Thanks to this solution idea, the adaptation of the diesel engine, from which the hydrogen-powered engine is derived, does not require either additional holes in the oil sump or the installation of additional electrical connections on the walls of the sump, with the related drawbacks discussed previously. In one embodiment according to the invention, the cap comprises an external electrical connector for connection to an electrical power circuit, and electrical connection devices connected, at one end, to the resistive electrical heating element and at the opposite end to the external electrical connector. In a further embodiment according to the invention, the oil pan comprises a plurality of side walls and the oil outlet hole is formed in one of the side walls; the resistive electric heating element extends inside the oil pan for a length equal to or greater than half the length of the oil pan. In one embodiment of the invention, the resistive electrical heating element extends inside the oil pan to a height equal to or greater than half the height of the oil pan. -4In one embodiment according to the invention the resistive electrical heating element extends along a median longitudinal vertical plane of the oil pan. In a further embodiment according to the invention, the end of the resistive electrical heating element inside the oil sump is arranged in a central area of ​​the oil sump. In one embodiment according to the invention the resistive electrical heating element has a tubular geometry. In one embodiment of the invention, the resistive electrical heating element comprises resistive materials, such as nichrome, which, when passed through by an electric current, resist the flow of electrons, converting the electrical energy into heat. In one embodiment according to the invention the resistive electrical heating element comprises a tube provided with a resistive electrical heating element which is wound helically along the tube. In one embodiment according to the invention, the resistive electrical heating element has a thread-like geometry. In one embodiment according to the invention, the resistive electric heating element is formed by two or more straight and / or curved sections forming a geometry such that the resistive electric heating element does not interfere with the dip tube and the oil level sensor and such that it can be inserted into and extracted from the oil sump from the oil outlet hole. In one embodiment according to the invention, the geometry of the resistive electric heating element is such that, when arranged within the oil pan, it can rotate together with the oil plug without interfering with the walls and bottom of the pan, with the suction pipe and with the oil level sensor. Brief description of the drawings The invention will now be described in detail with reference to the attached drawings, provided purely by way of non-limiting example, in which: - Figure 1 is a schematic perspective view of a hydrogen-fueled engine according to the invention, - Figure 2 is a perspective view of the oil pan of the engine in Figure 1, - Figure 3 is a side view of Figure 2, - Figure 4 is a top view of Figure 2, and - Figure 5 is a vertical section view along line VV of Figure 4. Detailed description of the invention The reference number 1 in Figure 1 generally indicates a hydrogen-powered internal combustion engine based on the invention. In the exemplified case, engine 1 borrows its architecture from a known type of engine, introducing the modifications that will be described below, mainly relating to its oil sump 6. The engine 1 comprises in a manner known per se a crankcase 2 which includes an aligned arrangement of cylinders and related pistons which, via respective connecting rods, drive a crankshaft not shown in the figures housed in a lower compartment 3 of the crankcase 2 and to one end of which a drive pulley 4 is keyed. Also in a manner known per se, the engine 1 is provided at the top with a cylinder head 5 which encloses a pair of camshafts driven by the drive pulley 4, and an arrangement of intake valves, intake ducts, exhaust valves and exhaust ducts associated with each of the cylinders. The engine 1 also includes in a known manner a combustion air supply system, the description of which is omitted here for brevity, as it is not relevant to the purposes of the invention. An oil pan, indicated as a whole by 6, is sealed underneath the crankcase 2. For this purpose, as can be seen in figures 2 and 4, the pan 6 comprises a flanged upper edge 7 which defines, in a manner known per se, a series of seats 8 for respective threaded fastening members, used to secure the pan 6 itself to the lower end of the crankcase 2, with the interposition of suitable sealing means. The oil pan 6 consists -6 notoriously of a bowl-shaped body formed by a pair of larger longitudinal side walls 11,12, a pair of smaller transverse side walls 13,14 and a bottom 15. On a lower central portion of the transverse side wall 13 there is a hole 16 provided with a closing plug 17, visible in figure 5, which allows the oil to exit from inside the pan 6, for example in the case of maintenance of the engine 1 or when it is necessary to replace the used oil. Referring to figures 2, 4 and 5, inside the oil sump 6 there are, always in a known manner, an oil level sensor 10 and a suction pipe 9, also called oil suction pipe, having the function of sucking the oil from the bottom of the sump 6 and conveying it towards an oil pump. Always referring to figures 2, 4, and 5, conveniently according to the invention, an elongated resistive electric heating element 18 is provided inside the oil pan 6 which extends from the oil outlet hole 16 to a median portion of the pan 6 substantially corresponding to 2 / 3 of the height and 2 / 3 of the length with respect to the hole 16. In other words, the electric heating element 18 comprises an end 19 at the oil outlet hole 16 and an opposite end 20 arranged in a central-forward portion of the oil pan 6. In the representation of the electric heating element 18 of figure 4 its end 19 is fitted into an internal portion of the cap 17, in an embodiment according to the invention, not shown in the figures, the cap 17 is conveniently formed integrally with the end 19 and therefore with the heating element 18. On the external surface of the cap 17 there is an electrical connector 21, better visible in figures 2 and 3, for connection to an electrical power circuit of the motor 1. Inside the cap 17, as visible in figure 4, there are electrical connection devices 22 which connect the electrical connector 21 to the end 19 of the heating element 18. Thanks to this solution idea, it is possible to install the resistive electric heating element 18 inside the oil sump 6 by introducing it from the hole 16, lock it in the operating position by means of the cap 17 which is coupled to the sump 6 with screw or interlocking means, and -7 power the heating element 8 by coupling a connector of the electrical power supply circuit of the engine 1 to the electrical connector 21 integrated in the cap 17, without the need to provide additional holes in the oil sump 6, which would lead to the inconveniences discussed previously, nor additional elements to be installed on the walls of the sump 6. This solution also allows for easy and quick maintenance of the heating element 18 which, once disconnected from the electrical connector 21, can be extracted from the sump 6 simply by removing the cap 17.Furthermore, considering that the oil drain plug 17 is notoriously located in an area of ​​the sump 6 that is easily accessible for maintenance of the engine 1, the heating element 18 integrated into it will also be easily accessible. In the embodiment of the invention represented in the figures, the resistive electric heating element 18 has a tubular geometry and comprises a first curvilinear section and three subsequent rectilinear sections which form a geometry such that the electric heating element 18 does not interfere with the dip tube 9 and with the oil level sensor 10, and such that it can be introduced into and extracted from the sump 6 from the oil outlet hole 16. Furthermore, the shape of the electric heating element 18 is such that, when placed within the oil pan 6, it can rotate together with the oil plug 17 without interfering with the walls 11,12,13,14 and the bottom 15 of the pan 6, with the dip tube 9 and with the oil level sensor 10. It is evident that different geometries and shapes of the resistive element can be envisaged which fall within the scope of protection of the present invention. The electric heating element 18 comprises resistive materials, such as nickel-chromium, which, when passed through an electric current, resist the flow of electrons, converting the electrical energy into heat, and may be coated in a protective material resistant to high temperatures and chemicals present in engine oil, such as stainless steel or anodized aluminum, to protect the heating element from corrosion and wear. Furthermore, the engine 1 according to the invention may comprise a control unit configured to enable the electrical supply of the resistive electric heating element 18 when the ambient temperature is below a predetermined threshold, and a thermostat that regulates the oil temperature, turning the heater 18 on and off to maintain the oil at an optimum temperature, depending on the specifications of the engine 1. Naturally, the construction details and embodiments may be varied widely with respect to those described and illustrated, without thereby departing from the scope of the present invention.

Claims

CLAIMS 1. A hydrogen-fuelled spark-ignition internal combustion engine (1), comprising: - a crankcase (2) with an aligned arrangement of cylinders, - a cylinder head (5) arranged to fill said crankcase (2), - an oil sump (6) sealed at a lower end of the crankcase (2) and comprising a dip tube (9), an oil level sensor (10), an oil outlet hole (16), a plug (17) for closing said hole (16) and an electrical resistive heating element (18), characterised in that said electrical resistive heating element (18) has an elongated shape and has an end (19) at said oil outlet hole (16).

2. Engine (1) according to claim 1, characterised in that said resistive electric heating element (18) is formed integrally with said closing cap (17) of the oil outlet hole (16).

3. Motor (1) according to claim 1 or 2, characterised in that said cap (17) comprises an external electrical connector (21) for connection to an electrical power supply circuit of the motor (1), and electrical connection devices (22) connected at one end to said resistive electrical heating element (18) and at the opposite end to said electrical connector (21).

4. Engine (1) according to any of the preceding claims, said oil pan (6) having a pair of transverse side walls (13,14) and wherein said oil outlet hole (16) is formed in one of said side walls (13,14), characterised in that said resistive electric heating element (18) extends inside the oil pan (6) for a length equal to or greater than half the length of the oil pan (6).

5. Engine (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) extends inside the oil sump (6) for a height equal to or greater than half the height of the oil sump (6).

6. Engine (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) extends along a median longitudinal vertical plane of the oil sump (6).

7. Engine (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) has an end (20) arranged in a central area of ​​the oil sump (6).

8. Engine (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) has a tubular geometry.

9. Motor (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) comprises nickel-chromium (nichrome).

10. Engine (1) according to any of the preceding claims, characterised in that said resistive electrical heating element (18) comprises a tube provided with a resistive electrical heating element (18) which is wound helically along the tube.

11. Motor (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) has a filiform geometry.

12. Engine (1) according to any of the preceding claims, characterised in that said resistive electric heating element (18) is formed by a plurality of rectilinear and / or curvilinear sections forming a geometry such that the resistive electric heating element (18) does not interfere with said dip tube (9) and said oil level sensor (10) and such that it can be introduced into and extracted from the oil sump (6) from said oil outlet hole (16).

13. Engine (1) according to claim 10, characterised in that said geometry of the resistive electric heating element (18) is such that, when placed within said oil sump (6), it can rotate -11 - together with said cap (17) without interfering with the walls (11,12,13,14) and a bottom (15) of the sump (6), with said dip tube (9) and with said oil level sensor (10).