Hydrogen internal combustion engine

Abstract

A hydrogen internal combustion engine with a cylinder block (610, Fig. 6) and cylinder head (410, fig. 4) together defining at least one cylinder 110, a port injection system 120 comprising two hydrog

Description

Field of Invention This invention relates to a Hydrogen internal combustion engine. Background of Invention Internal combustion engines have been in widespread use since at least the 1880s. They are used to provide motive force in transport applications, such as light duty vehicles and large goods vehicles. They are also used in stationary plant. In recent decades, electric motors have replaced some applications of combustion engines, particularly in hybrid and electric passenger cars. Hydrogen can be created relatively easily in many locations. The electrolysis of water provides Oxygen and Hydrogen. Thus the preconditions for Hydrogen production are a source of electrical power, such as a solar array, and a relatively simple Hydrogen electrolyser. The storage of Hydrogen is more technically demanding, and many available storage solutions are expensive and heavy. The cost and difficulty of storing Hydrogen has acted to limit the adoption of Hydrogen as a fuel. Where Hydrogen has been used in transport, a typical application has been to feed the Hydrogen into a fuel cell. The fuel cell generates electricity and water. The electricity can be used to provide motive power for the vehicle via an electric motor, and the water can be released as water vapour. Such fuel cell vehicles have now reached their third generation, with, for example, the Toyota Mirai™ and the Honda Clarity FCV™. Hydrogen has been used less often as a fuel for internal combustion engines. The applicant has recognised that there is a need for a Hydrogen internal combustion engine with optimised performance, which can also be relatively compact. Summary of the Invention According to an example of the invention, there is provided a Hydrogen internal combustion engine having the features of appended claim 1. A cylinder block and a cylinder head together define at least one cylinder. A port injection system comprises two hydrogen gas injectors per cylinder mounted in a dual injector block, the dual injector block functioning with a double feed-in and single feed-out configuration. A control system is configured to provide Hydrogen injection cycles with a pulse duration of 6-10 milliseconds, with each cycle providing 63-72 mg of Hydrogen gas into a combustion chamber of each cylinder. A pressure control valve is configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors at 6-10 bar, the pressure control valve being configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors during varying engine speeds and / or loads. Each cylinder of the hydrogen internal combustion engine may comprise: a combustion chamber having a bore to stroke ratio greater than one; a piston having a flat top; and an upper end of the combustion chamber being defined by a flat interior surface of the cylinder head. With this configuration, the piston and combustion chamber together provide a disk-shaped ignition space. The combustion chamber may have a bore to stroke ratio of 1.46. The inventors have found this bore to stroke ratio of 1.46 to be suitable for Hydrogen combustion, which does not result in unburned hydrocarbons as might be the case with engines that use more traditional fuels. Each cylinder may comprise: two spark plugs, each spark plug being cold-rated; two inlet valves; and two exhaust valves. Each cold-rated spark plug may be of a design that does not contain platinum. The cold-rated spark plugs transfers heat from the plug tip to the cylinder head quicker than a hot-rated spark plug. This means the chances of the spark plug tip igniting the air / fuel charge is reduced, which is particularly advantageous in the present engine. The hydrogen internal combustion engine may further comprise water cooling channels in the cylinder block, in the cylinder head and in an exhaust system. The hydrogen internal combustion engine may further comprise oil cooling passages configured to circulate oil to: an intake valve mechanism; an exhaust valve mechanism; and a camshaft. With this configuration, the intake valve mechanism and the exhaust valve mechanism are configured to be operated by the engine oil. The hydrogen internal combustion engine may further comprise a hydraulic valve actuation system. The hydrogen internal combustion engine may further comprise a fuel injection system comprising fuel injectors configured to deliver hydrogen fuel into intake ports, with one intake port located upstream of each inlet valve and outside the cylinder. Alternatively, the hydrogen internal combustion engine may comprise a direct fuel injection system comprising fuel injectors configured to deliver hydrogen fuel into each cylinder. The hydrogen internal combustion engine may further comprise a manifold, the fuel injectors being located in the manifold, with the manifold attached to the port injection system. The hydrogen internal combustion engine may further comprise the fuel injection system being configured to deliver hydrogen fuel, so as to provide an air to fuel ratio of 34:1 in the at least one cylinder. However, the fuel injection system may be configured to deliver hydrogen fuel, so as to provide an air to fuel ratio in the range of 130:1 to 180:1 in the at least one cylinder. The hydrogen internal combustion engine may further comprise a pressure-relief valve, the pressure relief valve being located in a crankcase of the cylinder block, and a ventilation system in the crankcase of the cylinder block, the ventilation system configured to allow water vapour to pass out of the cylinder block. The hydrogen internal combustion engine may further comprise sensors configured to monitor the temperature of the oil and water cooling systems. A first control system may be configured to receive temperature signals from the sensors, the control system being configured to dynamically adjust water coolant flow rates, oil circulation, and temperature regulation, thereby optimising performance under various driving or load conditions. The hydrogen internal combustion engine may further comprise a variable valve timing control system configured to control valve timing to maximise exhaust gas expulsion through the exhaust valves and air intake through the inlet valves, thereby maximising scavenging. Brief Description of the Figures Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. In the drawings, like reference numbers are used to identify like or functionally similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. Figure 1: illustrates a schematic diagram of the hydrogen internal combustion engine of the invention. Figure 2: illustrates a piston head in accordance with the invention. Figure 3: illustrates intake and exhaust valves in accordance with the invention. Figure 4: illustrates a view from above of a lower portion of a cylinder head. Figure 5: illustrates a view from below of the lower portion of the cylinder head. Figure 6: illustrates water and oil cooling channels in a cylinder block in accordance with the invention. Figure 7: illustrates a cam mounting shaft in accordance with the invention. Figure 8: illustrates a cam in accordance with the invention. Figure 9: illustrates exploded perspective views of a timing gear in accordance with the invention. Detailed Description The invention is a hydrogen internal combustion engine. The Hydrogen internal combustion engine of the invention provides a cylinder block and a cylinder head, which together define at least one cylinder. A port injection system comprises two hydrogen gas injectors per cylinder mounted in a dual injector block, the dual injector block functioning with a double feed-in and single feed-out configuration. A control system is configured to provide Hydrogen injection cycles with a pulse duration of 6-10 milliseconds, with each cycle providing 63-72 mg of Hydrogen gas into a combustion chamber of each cylinder. A pressure control valve is configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors at 6-10 bar, the pressure control valve is configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors during varying engine speeds and / or loads. The inventors have constructed the engine of the invention, which is referred to as an ‘M1H’ engine. Advantages of the Invention The Hydrogen internal combustion engine of the invention may provide the many advantages shown in Table 1 below: Feature in claim 1 Advantage Injection cycles with a pulse duration of 6-10 milliseconds Keeping the port injection pulse length at 6-10 milliseconds offers key advantages. It allows precise fuel metering, helping avoid pre-ignition and backfire due to hydrogen’s fast burn rate and low ignition energy. Short pulses ensure fuel is injected when the intake valve is fully open, reducing backflow and leakage. This duration supports high RPM operation without fuel delivery lag, and helps maintain optimal air-fuel mixtures, improving power and reducing NOx emissions. It also enables use of smaller injectors and simpler systems, which is ideal for retrofit applications. Each cycle provides 63-72 mg of Hydrogen gas into the combustion chamber Delivering 63-72 mg of hydrogen per cycle in the M1H Hydrogen Internal Combustion Engine ensures a balance of power, efficiency, and emissions control. This fuel mass supports lean-burn operation, for improved thermal efficiency and reduced NOx emissions, while avoiding pre-ignition, knocking, or intake backfire. It aligns with injector capabilities and ECU timing, ensuring stable combustion across engine speeds. The range of 63-72 mg also preserves air intake efficiency, by minimising displacement from hydrogen’s low density. Overall, it provides adequate energy for performance comparable to gasoline engines while supporting clean, controlled combustion suitable for emissions compliance and real-world useability / drivability in retrofit applications. Regulation of the pressure of Hydrogen gas fed to the Hydrogen gas injectors at 6-10 bar, including during variations of engine Regulating hydrogen gas pressure to 6-10 bar before injection provides optimal performance, safety, and control in a hydrogen internal combustion engine. This pressure range ensures consistent and precise fuel delivery, enabling accurate metering and stable combustion. It reduces the risk of injector leakage and backfire while maintaining sufficient flow rate for power output across different engine loads. Operating at 6-10 speeds and / or loads. bar also minimises stress on fuel system components, enhancing durability and safety. Additionally, it supports lean-burn strategies by allowing fine-tuned injection timing and quantity. An air to fuel ratio in the range of 130:1 to 180:1 in the at least one cylinder An air-to-fuel ratio of 130:1 to 180:1 in the at least one cylinder of the hydrogen internal combustion engine enables ultra-lean bum operation, significantly improving thermal efficiency and reducing fuel consumption. This extreme lean mixture lowers combustion temperatures, which drastically reduces nitrogen oxide (NOx) emissions without the need for complex aftertreatment systems. It also enhances engine cooling and allows stable combustion due to hydrogen’s wide flammability range. Operating one or more cylinders in this lean regime supports advanced combustion strategies like cylinder deactivation or stratified charge, helping optimise efficiency under light-load conditions, which is ideal for meeting strict emissions regulations while maintaining drivability. Table 1: Some advantages of the invention The M1H engine provides advantageous characteristics that may lead to deployment of the invention in many different applications. The applications may include at least: 5 (i) light-duty vehicles, such as tow-trucks, and vans; (ii) medium-duty vehicles, such as medium-haul and fire trucks; (iii) heavy-duty vehicles, such as concrete trucks; (iv)mining and construction vehicles, such as crawler dozers, excavators, and dump trucks; 10 (v) agricultural vehicles, such as harvesting machinery, tractors, grass-cutting vehicles and vehicles for planting or applying materials such as fertilizer; (vi) aircraft, such as propellor driven fixed-wing aircraft, airships, and hybrid aircraft; (vii) drones, remotely piloted aerial vehicles, and high altitude long duration aerial platforms; 15 (viii) ships and other water-craft; and (ix) fixed power plants, such as pumps, air conditioning and other stationary motors. Figure 1 shows a schematic diagram of a hydrogen internal combustion engine 100 in accordance with the invention. The hydrogen internal combustion engine comprises four cylinders 110. Each cylinder 110 has a combustion chamber 112. Each cylinder 110 is defined by a cylinder block and a cylinder head together, each of which is illustrated in detail in subsequent drawings. The invention may comprise more or fewer than four cylinders. A port injection system 120 comprises two hydrogen gas injectors 122 per cylinder, mounted in a dual injector block 124. Dual injector block 124 functions with a double feed-in and single feed-out configuration. The Dual injector block 124 is also referred to as the ‘manifold’. The port injection system mixes the fuel and air prior to it entering the combustion chamber, which limits the maximum theoretical power obtainable to approximately 85% of that of gasoline engines. The present invention may also be configured with a direct injection fuel system, which mixes the fuel with the air after the intake valve has closed, i.e. when the combustion chamber has 100% air. When configured with the direct injection fuel system, the maximum output of the engine can be approximately 15% higher than that for gasoline engines. Towards the right edge of figure 1 is shown pressure relief valve 126. Pressure relief valve 126 prevents the accumulation of Hydrogen within the crankcase. Since hydrogen has a lower energy ignition limit than gasoline, any unburnt hydrogen entering the crankcase has a greater chance of igniting. Pressure relief valve 126 prevents such Hydrogen accumulation. If Hydrogen were to ignite within the crankcase, a sudden pressure rise would occur within the crankcase. Pressure relief valve 126 is also capable of relieving this pressure within the crankcase. There is also a possibility of exhaust gases seeping by the piston rings of the engine into the crankcase. Since hydrogen exhaust is water vapor, water can condense in the crankcase when proper ventilation is not provided. The mixing of water into the crankcase oil would reduce the ability of the oil to provide lubrication, which would result in a higher degree of engine wear. Venting through pressure relief valve 126 may prevent this. A control system 130 is configured to provide Hydrogen injection cycles with a pulse duration of 6-10 milliseconds, with each cycle providing 63-72 mg of Hydrogen gas into the combustion chamber 112 of each cylinder 110. Constraining hydrogen injection pulse duration within the predefined range of 6-10 milliseconds produces the specific technical effects of maintaining optimal air-fuel ratio, whilst suppressing pre-ignition and backfire, stabilising combustion, balancing torque delivery, lowering NOx emissions, improving thermal efficiency, and protecting injector durability. The overall effect is to thereby enhance overall engine stability, safety and efficiency. Control system 130 comprises a pressure control valve 134 configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors 122 at 6-10 bar. Pressure control valve 134 is configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors 122 during varying engine speeds and / or loads. Selecting and maintaining hydrogen rail pressure within this predefined range, controlled as a constant injector differential pressure, produces the specific technical effects of stabilising injector mass flow and mixture homogeneity, thereby reducing combustion variability, lowering NOx formation, improving hot start robustness, and enhancing transient torque accuracy. These effects are achieved while protecting injector durability and simplifying diagnostics and calibration. The fuel injection system may be configured to deliver hydrogen fuel, so as to provide an air to fuel ratio of 34:1. At this air / fuel ratio, hydrogen will displace 29% of the combustion chamber leaving only 71% for the air. As a comparison with traditional engines, the energy content of this mixture at an air to fuel ratio of 34:1 will be less than it would be if the fuel were gasoline. The engine is sufficiently flexible that the fuel injection system may be configured to deliver hydrogen fuel, so as to provide leaner air / fuel ratios, such as an air to fuel ratio in the range of 130:1 to 180:1. Together with the use of dual spark plugs with a cold rating and non-platinum tips, an air to fuel ratio in the range of 130:1 to 180:1 may accommodate the wider range of flame speeds that occur over a greater range of equivalence ratios. At the very lean air / fuel ratios in the range 130:1 to 180:1, the flame velocity is reduced considerably and the use of a dual spark plug system provides better ignition. Platinum may in some circumstance act as a catalyst, causing Hydrogen to oxidise with air, so the spark plugs used have non-platinum tips. In the schematic diagram of figure 1, the control valve 134 is shown attached to a cylinder of Hydrogen gas. In practical implementations of the invention, the source of Hydrogen may for example be a vehicle-mounted Hydrogen tank. Such a Hydrogen tank may take one of many different geometrical shapes. As explained above, at least two configurations of fuel injection system are possible. The fuel injection system of the hydrogen internal combustion engine may comprise fuel injectors configured to deliver hydrogen fuel into intake ports, with one intake port located upstream of each inlet valve and outside the cylinder. However, alternatively, the fuel injection system of the hydrogen internal combustion engine may comprise a direct fuel injection system, comprising fuel injectors configured to deliver hydrogen fuel into each cylinder. One specific example of an M1H engine that the applicant has constructed has the features shown in Table 2 below. Parameter Value Capacity 998.1cc Bore 123mm Stroke 84mm Max RPM 7200 (9000) Max Power 85 BHP Max Torque 85 Nm Compression Ratio 9:1 to 13:1 (adjustable) Table 2: Parameters of an example of the Hydrogen internal combustion engine Figure 2 illustrates a piston head in accordance with the invention. At the left of figure 2, piston head 240 is shown in a side elevation cross-sectional view. The flat top 242 of piston head 240 is shown clearly at the left edge of that view. Piston head 240 is also shown at the right of figure 2, this time in a partial side elevation view. The flat top surface 242 of piston head 240 is now visible, this time at the upper edge. Figure 3 illustrates intake and exhaust valves in accordance with the invention. In figure 3, components at the top of a single cylinder are illustrated. There are two inlet valve hydraulic mechanisms 310, at the top, towards the rear of the drawing. There are two exhaust valve hydraulic mechanisms 312 at the top, further towards the front of the drawing. Towards the centre of figure 3, there are two cold-rated spark plugs 314. Towards the lower centre of figure 3, a side view of the exterior of the cylinder 318 is shown schematically. Towards the left of figure 3, pressure relief valve 320 is shown. Figure 4 illustrates a view from above of a lower portion of a cylinder head. In figure 4, towards the upper centre, cylinder head 410 has a pair of inlet valve openings 412. Below and towards the foreground of the figure, a pair of exhaust valve openings 414 are shown. Thus cylinder head 410 accommodates two inlet valves and two exhaust valves. The use of two exhaust valves decreases the probability of pre-ignition, as opposed to a single large exhaust valve, and these form part of an effective scavenging system, that is, a means of displacing exhaust gas from the combustion chamber 112 with fresh air. Figure 5 illustrates a view from below of the lower portion of the cylinder head of figure 4. In figure 5, it is apparent that the lower portion of the cylinder head 408 is generally flat. This surface therefore forms a flat top to the combustion chamber 412 of the cylinder, when the engine has been assembled. A disk-shaped combustion chamber 412, with the flat piston of figure 2 and the flat chamber ceiling, is used to reduce turbulence within the combustion chamber 412. The disk shape helps produce low radial and tangential velocity components, and does not amplify inlet swirl during compression. Figure 6 illustrates water and oil cooling channels in a cylinder block in accordance with the invention. Cylinder block 610 is shown in figure 6. The central aperture 612 of cylinder block 610 holds a barrel liner, which is not shown in figure 6. The dimensions of the central aperture 612 of cylinder block 610 are such as to provide a combustion chamber 112 with a bore to stroke ratio greater than one. The passages for water cooling provided in figure 6 ensures as closely as possible a uniform flow of water to the sections of the engine requiring cooling, all over the engine casings. The remainder of figure 6 illustrates a series of drilled holes, including: Hydraulic reservoir and non-return valve holes 620; Hydraulic piston sleeve holes 622; Oil return hole 624; Cross hole 626 for water, fitted for a plug to press in; A water passage hole 630 to meet the cross hole 626; and Holes 640 to hold the starter motor. Figure 7 illustrates a cam mounting shaft in accordance with the invention. Cam mounting shaft 710 is shown in an isometric view. Figure 8 illustrates a cam in accordance with the invention. Cam 810 is an illustrative example of both the inlet and the exhaust cams. Figure 9 illustrates an exploded perspective view of a timing gear in accordance with the invention. However, some individual elements within figure 9 are shown in cross-sectional view. The upper right view in figure 9 shows the valves of one cylinder. Inlet valves 910 are shown towards the rear and right of the view. Exhaust valves 912 are shown towards the front and left of the upper right view in figure 9. The upper right view in figure 9 can usefully be compared to the view in figure 3, where a different perspective is used to that used in the upper right view of figure 9. The left most view shown in figure 9 illustrates a hydraulic valve actuation mechanism 914. A gasket is shown at 916. Figure 9 provides a variable valve timing control system configured to control valve timing, to maximise exhaust gas expulsion through the exhaust valves and air intake through the inlet valves, thereby maximising scavenging. Discussion of advantages In addition to the advantages shown in Table 1, the invention may provide further advantages, as listed below. a) The disk shaped combustion chamber minimises both radial and tangential velocity components, while also preventing the amplification of the inlet swirl during the compression stoke. b) A large bore-to-stroke ratio, i.e. an engine design where the cylinder bore (the diameter of the cylinder) is significantly larger than the stroke (the distance the piston travels up and down within the cylinder), which may also be termed an "over-square" engine. Hydrogen engines do not have issues with unburnt hydrocarbons, and thus the over-square engine of the invention will not suffer the problems that over-square engines have shown in the past with some other fuels. An over-square engine may have some or all of the following advantages / features: (i) High RPM Potential. With a shorter stroke, the piston travels a smaller distance per cycle, reducing mechanical stress and allowing the engine to operate at higher speeds. This makes large bore-to-stroke ratio engines ideal for high-performance applications. (ii) Increased Valve Area. A larger bore allows for bigger valves, improving airflow into and out of the cylinder. This enhances the engine's ability to generate power at high speeds. (iii) Lower Torque at Low RPM. Shorter strokes reduce leverage on the crankshaft, leading to less torque production at low engine speeds. Such engines may rely on higher RPMs to achieve maximum power output. (iv) Efficiency and Combustion. The shape of the combustion chamber in large bore engines can sometimes lead to less efficient fuel combustion compared to engines with smaller bores. Advanced technologies, such as direct injection, help to mitigate this issue. c) The engine of the invention features a Dual Spark Plug System with a cold rating. The spark plugs have non-platinum tips, thereby helping to accommodate the wider range of flame speeds that occur over a greater range of equivalence ratios. This reduces the chances of the spark plug tip igniting the air / fuel charge. With the use of dual spark plug system, the flame velocity is reduced considerably. The inventors have found that Hydrogen has a broad flammability range, which potentially allows the M1H hydrogen engine to operate across air-fuel (A / F) ratios from 34:1 (stoichiometric) to very high values. This flexibility supports a wide range of operating conditions, from stoichiometric to extremely lean mixtures. The air-fuel ratio can also be expressed using the equivalence ratio, denoted by ¢\phi¢ (phi). The equivalence ratio is defined as the ratio of the stoichiometric A / F ratio to the actual A / F ratio: A / F .ratio Actual A / F ratio For a stoichiometric mixture, the actual A / F ratio equals the stoichiometric ratio, making ¢=1\phi = 10=1. For lean mixtures, ^1\phi <^<1. For example, a ¢\phi¢ value of 0.5 indicates that only enough fuel is present to oxidise with half of the available air. Alternatively, it means the air present is double the amount theoretically required for complete combustion. This adaptability in mixture ratios enhances the versatility and efficiency of hydrogen engines, enabling them to operate effectively across a wide spectrum of conditions. In some versions, the fuel injection system may be configured to deliver hydrogen fuel, so as to provide an air to fuel ratio in the range of 130:1 to 180:1 in the at least one cylinder. Hydrogen has a significantly smaller quenching distance compared to gasoline. This characteristic means hydrogen flames can travel much closer to the cylinder wall before extinguishing, making it more challenging to quench a hydrogen flame compared to a gasoline flame. The reduced quenching distance also increases the likelihood of backfire, as hydrogen-air flames can pass through a nearly closed intake valve more readily than hydrocarbon-air flames, potentially igniting the air-fuel mixture in unintended areas. Hydrogen has a relatively high autoignition temperature, which significantly influences the behaviour of hydrogen-air mixtures under compression. The autoignition temperature is a critical factor in determining the maximum compression ratio an engine can use without risking pre-ignition. Since the temperature of a gas mixture increases as it is compressed, the compression ratio directly affects whether the temperature will exceed the autoignition threshold of the fuel. For hydrogen, its high autoignition temperature allows for higher compression ratios compared to fuels with lower autoignition temperatures, but it also requires careful control to avoid conditions that might lead to unwanted ignition under extreme pressure and heat. 5 Hydrogen exhibits a high flame speed at stoichiometric air-fuel ratios, nearly an order of magnitude faster than gasoline flames. This rapid flame propagation allows hydrogen engines to operate closer to the thermodynamically ideal engine cycle, enhancing efficiency and performance. However, as the air-fuel mixture becomes leaner, the flame velocity of hydrogen decreases significantly, which can impact the combustion dynamics 10 and overall efficiency under such conditions. This variability in flame speed can be mitigated by optimising mixture conditions to achieve the desired engine performance. d) The Engine water-cooling system is extended comprehensively to all portions of the engine. As the engine of the invention runs hotter than a conventional fossil fuel engine, 15 the cooling system enables a uniform flow of the water coolant to the most vulnerable hot areas of the engine. This feature acts to counteract tendencies in other engines towards premature ignition, which occurs when the air-fuel mixture in an engine ignites before the spark plug fires. This can lead to inefficient combustion, causing rough engine operation and, in severe cases, backfire. 20 Premature ignition itself has presented problems in other Hydrogen fuelled engines. This is for multiple reasons, including Hydrogen having: (i) Lower ignition energy: Hydrogen requires less energy to ignite compared to other fuels, making it more susceptible to unintended ignition. 25 (ii) Wider flammability range: Hydrogen can combust across a broader range of air-fuel mixtures, increasing the risk of ignition under various conditions. (iii) Shorter quenching distance: The flame of hydrogen can persist closer to the cylinder wall, further contributing to the likelihood of premature ignition. 30 Aspects (i)-(iii) can lead to hot spots in the combustion chamber, such as residual heat on the spark plug, exhaust valve, or carbon deposits, which may trigger ignition. Valve overlap can also occur, when intake and exhaust valves are open simultaneously, whereby flames from the exhaust side may ignite the fresh air-fuel mixture. Oil pyrolysis can also occur, whereby high temperatures can decompose oil in the combustion chamber or crevices near the top piston ring. Pyrolysed oil can then seep into the combustion chamber. e) With the engine of the invention, additional steps to reduce the likelihood of preignition include using two exhaust valves, instead of a single large valve, and designing an efficient scavenging system. This system ensures the effective removal of exhaust gases from the combustion chamber, replacing them with fresh air. There are also two inlet valves. The valves are operated hydraulically by the engine oil. f) The pressure relief valve in the crankcase prevents Hydrogen accumulating in the crankcase. Hydrogen has a lower energy ignition limit than gasoline, so there is a risk of any unburnt hydrogen that enters the crankcase igniting. If hydrogen were to ignite within the crankcase, a sudden pressure rise would occur. The pressure relief valve can also relieve this pressure. Exhaust gases can also seep by the piston rings into the crankcase. Since hydrogen exhaust is water vapor, water can condense in the crankcase when proper ventilation is not provided. The mixing of water into the crankcase oil reduces its lubrication ability, resulting in a higher degree of engine wear. g) The Hydrogen gas is injected into the engine via two specialised injectors, specially designed and manufactured for Hydrogen. The injectors are injected into a special manifold, which is then connected to the engine. Modifying the hydrogen fuel delivery system of the present invention has proved to be an effective approach to minimising or eliminating pre-ignition issues. There are three primary types of hydrogen fuel delivery systems, each with distinct characteristics. They are (i) central injection, with the hydrogen-air mixture formed at the inlet of the air intake manifold; (ii) port injection, with Hydrogen injected at the intake port, closer to the cylinder than in central injection systems; and (iii) direct cylinder injection, with Hydrogen injected directly into the combustion chamber after the air intake valve has closed. Direct cylinder injection may offer advantages for minimising pre-ignition in hydrogen engines, as it ensures that the hydrogen-air mixture forms only in a controlled environment, isolated from potential ignition sources during the intake stroke. The present invention has been described with reference to the accompanying drawings. However, it will be appreciated that the present invention is not limited to the specific examples herein described and as illustrated in the accompanying drawings. Furthermore, because the illustrated embodiments of the present invention may for the most part be implemented using electronic components and circuits known to those skilled in the art, details have not been explained in any greater extent than that considered necessary as illustrated above, for the understanding and appreciation of the underlying concepts of the present invention and in order not to obfuscate or distract from the teachings of the present invention. The invention may be implemented in a computer program for running on a computer system, at least including code portions for performing steps of a method according to the invention when run on a programmable apparatus, such as a computer system or enabling a programmable apparatus to perform functions of a device or system according to the invention. A computer process typically includes an executing (running) program or portion of a program, current program values and state information, and the resources used by the operating system to manage the execution of the process. An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system. The computer system may for instance include at least one processing unit, associated memory and a number of input / output (I / O) devices. When executing the computer program, the computer system processes information according to the computer program and produces resultant output information via I / O devices. In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the scope of the invention as set forth in the appended claims and that the claims are not limited to the specific examples described above. Any arrangement of components to achieve the same functionality is effectively ‘associated’ such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as ‘associated with’ each other such that the desired functionality is achieved, irrespective of architectures or intermediary components. Likewise, any two components so associated can also be viewed as being ‘operably connected,’ or ‘operably coupled,’ to each other to achieve the desired functionality. Furthermore, those skilled in the art will recognise that boundaries between the above-described operations merely illustrative. The multiple operations may be combined into a single operation, a single operation may be distributed in additional operations and operations may be executed at least partially overlapping in time. Moreover, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in various other embodiments. However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense. In the claims, the word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms ‘a’ or ‘an,’ as used herein, are defined as one or more than one. Also, the use of introductory phrases such as ‘at least one’ and ‘one or more’ in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles ‘a’ or ‘an’ limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases ‘one or more’ or ‘at least one’ and indefinite articles such as ‘a’ or ‘an.’ The same holds true for the use of definite articles. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A hydrogen internal combustion engine, comprising:a cylinder block and a cylinder head together defining at least one cylinder;a port injection system, the port injection system comprising two hydrogen gas injectors per cylinder mounted in a dual injector block, the dual injector block functioning with a double feed-in and single feed-out configuration;a control system configured to provide Hydrogen injection cycles with a pulse duration of 6-10 milliseconds, with each cycle providing 63-72 mg of Hydrogen gas into a combustion chamber of each cylinder;the control system comprises a pressure control valve configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors at 6-10 bar, the pressure control valve being configured to regulate the pressure of Hydrogen gas fed to the Hydrogen gas injectors during varying engine speeds and / or loads.

2. A hydrogen internal combustion engine in accordance with claim 1, wherein each cylinder comprises:a combustion chamber having a bore to stroke ratio greater than one;a piston having a flat top; andan upper end of the combustion chamber being defined by a flat interior surface of the cylinder head;whereby the piston and combustion chamber together provide a disk-shaped ignition space.

3. A hydrogen internal combustion engine in accordance with claim 1 or claim 2, wherein each cylinder comprises:(i) two spark plugs, each spark plug being cold-rated;(ii) two inlet valves;(iii) two exhaust valves.

4. A hydrogen internal combustion engine in accordance with any previous claim, further comprising:water cooling channels in the cylinder block, in the cylinder head and in an exhaust system; andoil cooling passages configured to circulate oil to:(i) an intake valve mechanism;(ii) an exhaust valve mechanism; and(iii) a camshaft;whereby the intake valve mechanism and the exhaust valve mechanism are configured to be operated by the engine oil.

5. A hydrogen internal combustion engine in accordance with any of claims 1-3, further comprising:a hydraulic valve actuation system.

6. The hydrogen internal combustion engine of any previous claim, further comprising: a fuel injection system comprising fuel injectors configured to deliver hydrogen fuel into intake ports, with one intake port located upstream of each inlet valve and outside the cylinder.

7. The hydrogen internal combustion engine of any of claims 1-5, further comprising: a direct fuel injection system comprising fuel injectors configured to deliver hydrogen fuel into each cylinder.

8. The hydrogen internal combustion engine of claim 6 or claim 7, further comprising: a manifold, the fuel injectors being located in the manifold, with the manifold attached to the port injection system.

9. The hydrogen internal combustion engine of any of claims 6-8, further comprising: the fuel injection system configured to deliver hydrogen fuel, so as to provide an air to fuel ratio in the range of 130:1 to 180:1 in the at least one cylinder.

10. The hydrogen internal combustion engine of any of claims 6-8, further comprising: the fuel injection system configured to deliver hydrogen fuel, so as to provide an air to fuel ratio of 34:1 in the at least one cylinder.

11. The hydrogen internal combustion engine of any previous claim, further comprising: a pressure-relief valve, the pressure relief valve being located in a crankcase of the cylinder block; anda ventilation system in the crankcase of the cylinder block, the ventilation system configured to allow water vapour to pass out of the cylinder block.

12. A hydrogen internal combustion engine in accordance with claim 2, wherein the combustion chamber has a bore to stroke ratio of 1.46.

13. A hydrogen internal combustion engine in accordance with claim 3, wherein each cold-rated spark plug does not contain platinum.

14. A hydrogen internal combustion engine in accordance with any previous claim, further comprising:sensors configured to monitor the temperature of the oil and water cooling systems; anda first control system configured to receive temperature signals from the sensors, the control system being configured to dynamically adjust water coolant flow rates, oil circulation, and temperature regulation, thereby optimising performance under various driving or load conditions.

15. A hydrogen internal combustion engine in accordance with any previous claim, further comprising:a variable valve timing control system configured to control valve timing to maximise air intake through the inlet valves and exhaust gas expulsion through the exhaust valves, thereby maximising scavenging.A

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