System for lubricating an injector of a hydrogen internal combustion engine

Abstract

The invention concerns a system for lubricating an injector (1) of a hydrogen internal combustion engine, the system (1) comprising at least: - a tank (2) containing an aqueous solution, the aqueous solution comprising water and a lubricating additive; - a pump (3); and, - a first injection line (4) configured to deliver the aqueous solution to an injector. wherein the lubricating additive is a compound with a general formula CnHmXz, being X selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5.

Description

System for lubricating an injector of a hydrogen internal combustion engine

[0001] The invention relates to a system for lubricating an injector of a hydrogen internal combustion engine and to systems integrating said system for lubricating an injector of a hydrogen internal combustion engine, such as a system of injection of hydrogen of a hydrogen internal combustion engine, a hydrogen internal combustion engine and a hydrogen internal combustion engine vehicle.

[0002] The invention can be used in the field of vehicles, and especially, in the field of hydrogen internal combustion engine vehicle. By “vehicle”, we mean any motor vehicle such as a car, a motorcycle, a truck, a bus, a train, a machine, in particular a construction machine.

[0003] In an internal combustion engine using hydrogen as fuel, a hydrogen injector is used to inject hydrogen into the combustion chamber of the internal combustion engine. Once hydrogen is injected into the combustion chamber, a reaction between hydrogen and oxygen (also introduced in the combustion chamber) takes place and produces water vapor and energy which is converted into mechanical energy to propel the vehicle. Documents CN 221 002 941 U and JP 2023 182740 A disclose examples of internal combustion engines using hydrogen as fuel. Document WO 2021 / 136817 A1 discloses an example of system for injecting an aqueous solution in an engine.

[0004] A hydrogen injector typically comprises a moving part with one or multiples needles, and a static housing including one or more holes. The injector is closed when the needles enter in contact with the static housing, in such a manner that the injection holes are closed. The injector is open when the needles are lifted, and no longer in contact with the housing, so that the holes are open, and hydrogen can flow through the injector and leave the injector by the injection holes. The opening and closing movements of the injector are very fast, typically a time of approximately 1millisecond or lower. Both the needles and the injector housing are typically made of hard material, usually metal, and a metal-on-metal impact at high speed creates very high local pressures, which can lead to local part deformation. Therefore, repeated metal on metal impacts at high speed but also simple frictions deform the needles or the housing, resulting in a loss of leak tightness when the injector is closed and, generally, in a loss of capability to open and close correctly, this leading to a premature wear of the injector.

[0005] To resolve this problem, existing technical solutions are mainly based on lubrication of the injector by adding oil with water or only water into the injector with the aim of limiting frictions and collisions. Indeed, since hydrogen has no lubricating characteristics, and since hydrogen is a very low viscosity gas, it cannot contribute to reduce the pulse of the impact of the needles on the housing.

[0006] The disadvantage of these technical solutions is that the oil subjected to high temperatures produces CO2, that the water does not allow sufficient lubrication, that the water freezes at certain temperatures with which the vehicle comes into contact, that the use of heating devices to prevent water from freezing requires purging and that water requires decontamination of traces of organic matter, bacteria and algae.

[0007] The object of the present invention is therefore to propose a system for lubricating an injector of a hydrogen internal combustion engine, which makes it possible to ensure adequate protection of the injector against premature wear while overcoming the disadvantages previously mentioned.

[0008] Another object of the invention is to propose a system of injection of hydrogen of a hydrogen internal combustion engine comprising a system for lubricating an injector of a hydrogen combustion engine and an injector, with the purpose of protecting the injector against premature wear.

[0009] Another object of the invention is to propose a hydrogen internal combustion engine comprising a system of injection of hydrogen of a hydrogen internal combustion engine, also with the purpose of avoiding the injector premature wear.

[0010] Another object of the invention is to propose a hydrogen internal combustion engine vehicle comprising a system for lubricating an injector of a hydrogen combustion engine also allowing to protect the injector against premature wear.

[0011] To this end, the invention relates to a system for lubricating an injector of a hydrogen internal combustion engine.

[0012] According to the invention, such a system is such that it comprises at least:a tank containing an aqueous solution, the aqueous solution comprising water and a lubricating additive;a pump; and,a first injection line configured to deliver the aqueous solution to an injector.wherein the lubricating additive is a compound with a general formula CnHmXz, where X being selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5.

[0013] The general principle of the invention is based on the lubrification of the injector by an aqueous solution comprises water and a lubricating additive of a general formula CnHmXz(being X selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5). Thus, due to the addition of this aqueous solution, the invention is based on a completely new and inventive approach to obtain a sufficient lubricating effect in the injector (superior to the lubricating effect of only water), which not requires the use of oil and its disadvantages. Moreover, the use of an aqueous solution comprising water with a lubricating additive makes it possible to overcome problems linked to the use of water only, which could freeze or become contaminated.

[0014] More precisely, the addition of the previously mentioned lubricating additive allows to create a water “cushion” effect resulting in slowing down the needle prior to impacting the seating surface, which lead to increase the injector lifetime. Generally, the addition of the CnHmXzadditive (where X being selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5) improves the surface wetting characteristic (compared to using water alone) by allowing the aqueous solution to enter into narrow spaces (for instance sliding bushes from the injector), and reduces surface friction, particularly, in this narrow spaces.

[0015] According to a preferred embodiment, the pump is in contact with the tank and works in cooperation with the injector line to feed a desired quantity of the aqueous solution in the dedicated area of the injector. The dedicated area of the injector corresponds to the location of the static housing of the injector which includes one or more holes.

[0016] According to a preferred embodiment, the aqueous solution is expelled by the pump to go through the first injection line. The aqueous solution goes through the first injection line while being driven by the pump. The first injection line comprises a fluid conduct.

[0017] According to a preferred embodiment, the first injection line is positioned, so that this desired quantity of the aqueous solution goes in the dedicated injector area by passing by the first injection line.

[0018] According to a preferred embodiment of the previous mode, the lubricating additive is a water-soluble additive. The water-soluble character of an additive is defined by the amount of that additive that is dissolved in a given amount of water. An additive is said to be soluble if more than 0.1g of that additive can be dissolved be mixing it with 100g (or about 100mL at 20°C) of water (at about 20°C). Thus, given that the lubricating additive is a water-soluble additive, the mixture between water and the lubricating additive is a homogenous mixture, which permits to obtain a reliable and repeatable lubricating effect.

[0019] According to a preferred embodiment, the lubricating additive is a biocide. The term “biocide” is defined in European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless or exert a controlling effect on any harmful organism. The United States Environmental Protection Agency ("EPA") uses a slightly different definition for biocides: "a diverse group of toxic substances including preservatives, insecticides, disinfectants and pesticides used to control organisms which are harmful to human or animal health or which cause damage to natural or manufactured products". For the purposes of the present invention, both definitions are applicable. Thus, the fact that the lubricating additive is a biocide allows that traces of organics, bacteria and algae are in limited quantity, or even not contained in the mixture between water and the lubricating additive. Indeed, water is commonly found with traces of organics, bacteria and algae, which can block the entire system by creating biofilm, solid compounds, for example.

[0020] According to a preferred embodiment, the lubricating additive is a water antifreeze agent. Therefore, the fact that the lubricating additive is a water antifreeze agent allows to avoid the mixture in the injector from freezing from -40°C up to 0°C. Indeed, typical automotive applications and specification require the vehicle to operate in all climatic conditions in the world. Typically, the temperature range, for all climatic conditions in the world, goes from -40°C up to 80°C.

[0021] According to a preferred embodiment, the lubricating additive is a compound with a general formula CaHb(OH)c,a being an integer selected from 1 to 5, b being an integer selected from 3 to 11 and c being an integer selected from 1 to 5. The fact that the lubricating additive is a CaHb(OH)c, which is an alcohol allows the mixture placed in the injector to have an anti-bacteria behaviour and an anti-freeze behaviour (better than water). Indeed, freezing temperature of alcohol containing liquids is typically lower than 0°C. Also, alcohol is an organic molecule which has the ability to keep and stop the bacteria propagation.

[0022] According to a preferred embodiment, the lubricating additive is methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, diols (including ethylene glycol), polyalcohols (including glycerol), amino alcohols, aldols, ketols or acyloins or a combination thereof.

[0023] According to a preferred embodiment, the lubricating additive is ethylene glycol. Thus, given that the lubricating additive is ethylene glycol allows that the mixture places in the injector have an anti-freeze effect.

[0024] According to a preferred embodiment, a concentration of the lubricating additive in water ranges from 30 to 50% by volume. So, given that the concentration of the lubricating additive in water is from 30% to 50% by volume of water, the mixture water with the lubricating additive does not freeze above approximately -40°C which is the value at which the automotive lowest temperature applications are made.

[0025] The invention also relates to a system of injection of hydrogen of a hydrogen internal combustion engine comprising a system for lubricating an injector of a hydrogen internal combustion engine compliant with the system for lubricating an injector of a hydrogen combustion engine aforementioned and a second injection line configured to deliver hydrogen to an injector. So, due to these characteristics, the system of injection of hydrogen of a hydrogen internal combustion engine allows to protect the injector against frictions and impacts between parts in the injector, which lead to increase the lifetime of the injector. Indeed, the addition of the CnHmXzadditive for lubricating the injector improves the surface wetting characteristic of aqueous solution by allowing aqueous solution to enter narrow spaces (for instance sliding bushes from the injector) and creates a water “cushion” effect resulting in slowing down the needle prior to impacting the seating surface.

[0026] According to a preferred embodiment, in the system of injection of hydrogen, the first injection line is connected to the injector and the second injection line is connected to the first injection line. In this way, the first injection line is configured to simultaneously deliver the aqueous solution and hydrogen. The term “simultaneously” used in the expression “the first injection line is configured to simultaneously deliver the aqueous solution and hydrogen” means that the first injection line is configured to deliver exactly at the same time the aqueous solution and hydrogen or to deliver, at a different time but a difference of time between each injection (the aqueous solution and hydrogen) less than 1 / 10s. More precisely, it is necessary that, during the movement of the piston, an entire rotation of the crankshaft, therefore 360°, both injections must have taken place.As, the first injection line is configured to simultaneously deliver the aqueous solution and hydrogen, the injector is built to inject both hydrogen and the aqueous solution with the same injector at the same time and so, for each injection pulse of hydrogen, a fixed quantity of mixture water with the lubricating additive is added to assure the lubricating effect. Therefore, this avoids the need for a precise and homogenous pre-mixing of hydrogen with the aqueous solution upstream the injector. Moreover, it allows to have the right amount of injected aqueous solution needed to lubricate the injector depending on the amount of hydrogen injected. Additionally, it simplifies the system of injection by having only one component since a single injector fulfils all function.

[0027] According to a preferred embodiment, in the system of injection of hydrogen, the first injection line and the second injection line are connected to the injector. The fact of using two injection lines allows to choose the dose of hydrogen and the dose of aqueous solution independently from one another. When the aqueous solution is injected mostly for its cooling effect in the combustion chamber, and especially when the engine is used at high load, high quantities of cooling liquid are required. When the liquid is injected purely for lubrification, but the engine load is so low that no combustion chamber cooling is required, the aqueous solution dosing should be limited to a minimum.

[0028] According to a preferred embodiment, in the system of injection of hydrogen, the hydrogen is injected into a combustion chamber of the hydrogen internal combustion engine. This “direct injection” embodiment ensures reliable lubrication and cooling of injector needles operating under high-pressure hydrogen conditions and high-speed actuation in the combustion chamber. This also reduces friction and wear caused by metal-to-metal contact, thereby extending injector lifetime, even in severe thermal and pressure cycles typical for direct injection systems.

[0029] According to a preferred embodiment, in the system of injection of hydrogen, the hydrogen is injected into an intake manifold or intake port of the hydrogen internal combustion engine. This “indirect injection” embodiment allows to maintain injector durability in systems where hydrogen is introduced upstream, where there is lower in-cylinder cooling effect, meaning lubrication becomes even more critical. This also facilitates integration with port injectors, which can have longer opening times and higher frequency, leading to significant mechanical wear if not lubricated.

[0030] More generally, the system of injection of hydrogen according to the invention provides a water-lubricant film effect and antifreeze / biocide properties, avoiding disadvantages of oil or pure water lubrication, i.e. CO₂ emission, freezing, biofilm formation to name a few examples. The system also allows flexible architecture, whether hydrogen injection occurs directly or indirectly, and lubrication remains optimized by dosing aqueous solution proportional to injector activity.

[0031] The present disclosure also relates to a hydrogen internal combustion engine comprising a system of injection of hydrogen of a hydrogen internal combustion engine compliant with the system of injection of hydrogen of a hydrogen internal combustion engine aforementioned. In the same way as for the system of injection of hydrogen of a hydrogen internal combustion engine, the hydrogen internal combustion engine as it comprises the system of injection of hydrogen of a hydrogen internal combustion engine allows to protect the injector.

[0032] The present disclosure also relates to a hydrogen internal combustion engine vehicle comprising a system for lubricating an injector of a hydrogen internal combustion engine compliant with the system for lubricating an injector of a hydrogen combustion engine aforementioned. So, given that the hydrogen internal combustion engine vehicle comprising the system previously mentioned for lubricating an injector of a hydrogen combustion engine (due to the aqueous solution comprising water and a lubricating additive), this hydrogen internal combustion engine vehicle allows to reduce surface frictions and impacts between parts in the injector, which lead to increase the injector lifetime.

[0033] Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given by way of a simple illustrative and non-limiting example, and the appended drawings, among which:illustrates a hydrogen internal combustion engine integrating a system for lubricating an injector of said hydrogen internal combustion engine according to the invention, said system comprising one injection line to deliver the aqueous solution and hydrogen to the injector.illustrates an embodiment of the invention where the system for lubricating an injector of a hydrogen internal combustion engine comprises two injection lines, one to deliver the aqueous solution to the injector and one to deliver hydrogen to the injector.illustrates a hydrogen internal combustion engine vehicle comprising a system for lubricating an injector of a hydrogen combustion engine according to an embodiment of the invention.

[0034] An internal combustion engine generally works in cycles comprising:an intake phase where the fuel is introduced in a combustion chamber. In some cases, the fuel is initially in the combustion chamber,a compression phase where the fuel is compressed by a piston slidably moving between a bottom position and a top position,a combustion phase where the fuel is ignited, andan exhaust phase where burned gases are evacuated.

[0035] is a schematic illustration of a system of injection of hydrogen 8 into a hydrogen internal combustion engine comprising a system for lubricating an injector 1 of said hydrogen internal combustion engine, the system 1 having one first injection line 4 for hydrogen and the aqueous solution. The first injection line 4 collaborates with the second injection line 5 to deliver hydrogen to the injector. The second injection line 5 is connected to the first injection line 4. The hydrogen is introduced into the combustion chamber 12 of the engine where it burns with the oxygen. The chemical energy of the hydrogen reacting with oxygen may be converted into mechanical energy to propel the vehicle via the movement of the piston 9.

[0036] Hydrogen and oxygen are introduced separately, through intake ports, into the combustion chamber 12 of the internal combustion engine. As it is necessary to inject a precise quantity of hydrogen to control combustion, hydrogen is introduced in the combustion chamber 12 by an injector 6. Also, hydrogen can be injected into the air flow comprising oxygen and it is the air and hydrogen mixture which enters the chamber 12. More precisely, hydrogen can be introduced before entering the combustion chamber 12 (in the air flow) or directly in the combustion chamber 12. To ensure that the ratio of oxygen and hydrogen quantities is correct in the combustion chamber 12, temperature and pressure sensors can be used. Hydrogen and oxygen are respectively provided via the injection lines 4, 5 and the air duct 11.

[0037] A system of injection of hydrogen 8 connects to high pressure hydrogen tanks 10 supplying hydrogen (at a pressure comprises between 0 and 50 bars) so that it goes to the combustion chamber 12 through the injector 6. In fact, it is necessary for the hydrogen to exit the tank 10 at a pressure between 0 and 50 bars for the injector 6 to operate correctly.

[0038] In a hydrogen internal combustion engine, a spark plug can be used so that the hydrogen burns with the oxygen. Also, a fluid conduit can be used in connection with the combustion chamber 12 so that the exhaust gases can be evacuated from the combustion chamber 12. The exhaust gases can pass through a system of selective catalytic reduction (SCR) to reduce nitrogen oxide (NOx) to N2of the exhaust gases.

[0039] The hydrogen injector 6 typically consists of a moving part with one or multiples needles, and a static housing including one or more holes. The injector 6 is closed when the needles enter in contact with the housing, in such a manner that the injection holes are blocked. The injector is open when the needles are lifted, and no longer in contact with the housing, so that the holes are open, and hydrogen can flow through the injector and leave the injector by the injection holes.

[0040] The system for lubricating an injector 1 of said hydrogen internal combustion engine comprises a tank 2 containing an aqueous solution, a pump 3 for pumping the aqueous solution, a first injection line 4 (also called “feeding line”). The aqueous solution lubricates the injector 6 in a way that the moving part (needle) and the injector housing can no longer collide. Said aqueous solution comprises water and a lubricating additive. The lubricating additive is a compound with a general formula CnHmXz, being X selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5.

[0041] As illustrated on, the aqueous solution (comprising water and a lubricating additive) allows to lubricate the injector 6, the water of the aqueous solution has also a cooling effect which is necessary in the combustion chamber 12 and in the injector 6. Indeed, each type of injector is defined by a maximum operating temperature necessary to avoid premature wear. In the combustion chamber 12 and outside the combustion phase, hot spots may be present, particularly at the spark plug. Since these hot spots must be avoided to avoid pre-combustion, it is necessary to carry out cooling of these hot spots in the combustion chamber 12.

[0042] The pump 3 is preferably placed close to the tank 2 and allows in cooperation with the first injection line 4 to feed a desired quantity of the aqueous solution in contact with the dedicated injector area. For that, advantageously, the aqueous solution goes to the first injection line 4 (which comprises a fluid conduct) while being driven by the pump 3. More precisely, the first injection line 4 is positioned, so that this desired quantity of the aqueous solution can go in the dedicated injector 6 area by passing by the first injection line 4. The lubricating additive can be a water-soluble additive, which can have a biocide or / and a water anti-freezing effect. Preferably, the lubricating additive is a compound with a general formula CaHb(OH)c, a being an integer selected from 1 to 5, b being an integer selected from 3 to 11 and c being an integer selected from 1 to 5. More preferably the additive is methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, fatty alcohols, diols (including ethylene glycol), polyalcohols (including glycerol), amino alcohols, aldols, ketols or acyloins or a combination thereof. The most preferably, the lubricating additive is ethylene glycol.

[0043] Preferably, the concentration of the lubricating additive in water is ranged from 30 to 50% by volume. Preferably, the concentration of the lubricating additive in water is from 30%, 35%, 40%, 45% and 50% by volume.

[0044] Preferably, in the system of injection of hydrogen 8, the first injection line 4 is configured to deliver both the aqueous solution and hydrogen at the same time in the injector 6.

[0045] illustrates an alternative to the system presented on. The system of injection of hydrogen 8 comprises two injection lines 4, 5’. The second injection line 5’ solely delivers hydrogen. Whereas the second injection line 5’ operates independently of the first injection line 4 configured to deliver the aqueous solution.

[0046] Thus, the aqueous solution can be introduced by the first injection line 4 before hydrogen is introduced by the second injection line 5’ into the injector. More precisely, the aqueous solution can be introduced in the injector before the end of the introduction of hydrogen in the injector and before closing the injector (that is to say before the needle is in contact with the static housing). Also, the aqueous solution and hydrogen can be introduced at the same time into the injector. To do this, the two injection lines 4, 5’ join at the inlet (or further into the injector) of the injector where the aqueous solution mixes with hydrogen.

[0047] illustrates vehicle 20 comprising a hydrogen internal combustion engine 7 comprising the system of injection of hydrogen 8 as illustrated on figures 1 or 2.Reference list:

[0048] System for lubricating an injector of a hydrogen internal combustion engineTankPumpInjection lineSecond injection lineInjectorHydrogen internal combustion engineSystem of injection of hydrogen of a hydrogen internal combustion enginePistonHydrogen tanksAir ductCombustion chamberHydrogen internal combustion engine vehicle

Claims

A system for lubricating an injector (1) of a hydrogen internal combustion engine (7), the system (1) is characterized in that it comprises at least:a tank (2) containing an aqueous solution, the aqueous solution comprising water and a lubricating additive;a pump (3); and,a first injection line (4) configured to deliver the aqueous solution to an injector,wherein the lubricating additive is a compound with a general formula CnHmXz, where X being selected from a group consisting of amide, hydroxyl, carbonyl and combinations of at least two thereof, n being an integer selected from 1 to 6, m being an integer selected from 3 to 13 and z being an integer selected from 1 to 5.The system (1) according to claim 1, wherein the lubricating additive is a water-soluble lubricant.The system (1) according to any one of claims 1 to 2, wherein the lubricating additive is a biocide.The system (1) according to any one of claims 1 to 3, wherein the lubricating additive is a water antifreeze agent.The system (1) according to any one of claims 1 to 4, wherein the lubricating additive is a compound with a general formula CaHb(OH)c, a being an integer selected from 1 to 5, b being an integer selected from 3 to 11 and c being an integer selected from 1 to 5.The system (1) according to any one of claims 1 to 5, wherein the lubricating additive is ethylene glycol.The system (1) according to any one of claims 1 to 6, wherein a concentration of the lubricating additive in water ranges from 30 to 50% by volume.A system of injection of hydrogen (8) of a hydrogen internal combustion engine (7) comprising the system for lubricating an injector (1) of a hydrogen internal combustion engine (7) according to any one of claims 1 to 7 and a second injection line (5, 5’) configured to deliver hydrogen to an injector (6).The system of injection of hydrogen (8) according to claim 8, wherein the first injection line (4) is connected to the injector (6) and the second injection line (5) is connected to the first injection line (4).The system of injection of hydrogen (8) according to claim 8, wherein the first injection line (4) and the second injection line (5’) are connected to the injector (6).The system of injection of hydrogen (8) according to any one of claims 8 to 10, wherein the hydrogen is injected into a combustion chamber (12) of the hydrogen internal combustion engine (7).The system of injection of hydrogen (8) according to any one of claims 8 to 10, wherein the hydrogen is injected into an intake manifold or intake port of the hydrogen internal combustion engine (7).

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