Internal combustion engine

Abstract

A gaseous fuel internal combustion engine includes: an engine structure including a crankcase and an oil reservoir located below the crankcase; and a ventilation system including a gas pressure source configured to deliver a blow-by gas including a gaseous fuel from the crankcase as an exhaust gas. The ventilation system includes a first oil separator configured to reduce an oil concentration in the exhaust gas. The ventilation system is configured such that, in use, the gas pressure in the crankcase is higher than the gas pressure in the first oil separator. The engine includes a first exhaust conduit arranged to deliver oil removed from the exhaust gas by the first oil separator to the oil reservoir. The first discharge conduit is configured to hold an oil head that exerts a hydrostatic pressure on oil in the oil reservoir for, in use, inhibiting delivery of gas in the crankcase to the oil separator via the first discharge conduit.

Description

Technical Field

[0001] This teaching relates to internal combustion engines, and more particularly to gas-fueled internal combustion engines. Background Technology

[0002] In internal combustion engines, it is common for air and fuel in the cylinder's combustion chamber, as well as the combustion gases formed in the combustion chamber, to leak to some extent from the combustion chamber through the piston into the engine's crankcase. This leaking gas is commonly referred to as blow-by gas.

[0003] In engines powered by gaseous fuels such as hydrogen, inadequate ventilation can lead to problems as leaked gaseous fuel components accumulate in the crankcase. This is because some gaseous fuels have a relatively high flammability range (e.g., hydrogen has a flammability concentration in air between 4% and 75%). Unless the leak is ventilated to reduce the concentration of gaseous fuel in the crankcase below its lower flammability limit, there is a risk that the gaseous fuel in the crankcase may ignite, potentially damaging the engine and its surrounding environment. The gaseous fuel may then ignite the lubricating oil in the crankcase, triggering further combustion.

[0004] A crankcase ventilation system is known to be configured to ventilate leaking gas from the crankcase of a gas-fueled internal combustion engine. Oil serves as a lubricant throughout the engine and is transported through the engine from an oil sump. Gases expelled from the crankcase via the crankcase ventilation system carry oil from the crankcase. To reduce oil waste and minimize emissions, it is desirable to separate the oil from the gas. Since higher levels of ventilation airflow are typically required in gaseous (especially hydrogen) fuel engines, the amount of oil wasted can be significantly higher than in diesel or gasoline fuel engines.

[0005] A crankcase ventilation system is known to include an oil separator for separating oil from gases discharged from the crankcase. However, due to the pressure difference between the oil sump and the oil separator, oil may not be able to drain from the oil separator to the oil sump during engine operation.

[0006] This teaching attempts to overcome or at least mitigate one or more problems associated with existing technologies. Summary of the Invention

[0007] This teaching provides a gas-fueled internal combustion engine according to the appended claims.

[0008] A first aspect of this teaching provides a gas-fueled internal combustion engine comprising: a crankcase; and a ventilation system configured to discharge leaks contained within the crankcase.

[0009] The engine may include an engine structure. The engine structure may include a crankcase and a gearbox. The ventilation system may include a gas pressure source and a ventilation path. The gas pressure source may be configured to deliver ventilation gas along the ventilation path from a gas inlet to a first portion of the gearbox, and then to the crankcase. The gas pressure source may be configured to deliver a combination of ventilation gas and leaked gas, including gaseous fuel, as exelled gas from the crankcase via a separate outlet.

[0010] Advantageously, directing ventilation gas from the gas inlet to the gearbox and then to the crankcase helps reduce the concentration of leak gas in the gearbox, thereby reducing the risk of leak-induced combustion in the gearbox and reducing the exposure of gearbox components to the leak. By reducing the exposure of gearbox components to the leak, the risk of exposure-related damage to these components (e.g., via hydrogen embrittlement) is reduced.

[0011] In addition, this configuration of the ventilation system can help improve the encapsulation of the inflow portion of the ventilation path.

[0012] The outlet may include an outflow portion of the ventilation path. A section of the outflow portion may be arranged within the engine structure.

[0013] Advantageously, this configuration of the outflow section can help suppress leak freezing due to the temperature rise of the engine structure during operation. This is particularly beneficial when the gaseous fuel is hydrogen, as leaks may include a high concentration of water vapor as a byproduct of hydrogen combustion.

[0014] The engine structure may also include a cylinder block, a cylinder head, and / or a rocker arm cover. The outlet portion may pass through one or more of the cylinder block, cylinder head, rocker arm cover, and a second part of the gearbox. The second part of the gearbox may be separable from the first part of the gearbox.

[0015] Advantageously, this configuration can help improve the encapsulation of the outflow section and avoid the need for a piping system located outside the engine, which may be vulnerable to damage.

[0016] The outflow portion can continuously (in series) pass through at least the cylinder bank, cylinder head, and rocker arm cover.

[0017] Advantageously, this configuration can help improve the packaging of the outflow portion.

[0018] The outflow portion can pass through the second part of the gearbox. The second part of the gearbox can be separated from the first part of the gearbox.

[0019] Advantageously, this configuration can help improve the packaging of the outflow portion.

[0020] The gas pressure source can be configured to deliver ventilation gas from the gas inlet to the crankcase along the inflow portion of the ventilation path. The outlet may include the outflow portion of the ventilation path.

[0021] The ventilation system may include a routing unit mounted adjacent to the engine structure. The routing unit may include: a housing; an inflow duct located in the inflow portion of the ventilation path; and an outflow duct located in the outflow portion of the ventilation path. The inflow and outflow ducts may be at least partially housed within the housing.

[0022] Advantageously, combining the inflow and outflow ducts into a single routing unit can help improve the enclosure of the ventilation system and simplify engine assembly.

[0023] The outflow conduit may include an oil pre-separator configured to reduce the oil concentration in the exhaust gas.

[0024] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0025] Oil pre-separators can be passive oil pre-separators.

[0026] The gas pressure source can be located downstream of the crankcase. The outflow conduit can be located upstream of the gas pressure source.

[0027] Advantageously, an oil pre-separator can help reduce the amount of oil in the exhaust gas flowing through the gas pressure source, which can help improve the efficiency of the gas pressure source and / or reduce damage to the gas pressure source.

[0028] The routing unit can be installed adjacent to the gearbox.

[0029] The inflow portion of the ventilation path can enter the first part of the gearbox via an orifice in the gearbox. The gearbox orifice can be located downstream of the inflow duct. The routing unit can be mounted adjacent to the gearbox orifice.

[0030] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0031] The routing unit can cover the gearbox opening.

[0032] The first part of the flow into the conduit and gearbox can be continuous.

[0033] The gearbox orifice can be located in the front-facing wall of the gearbox.

[0034] In liquid-fueled engines, an orifice is typically located at this position to transfer driving force from the gearbox to the fuel injection pump, so the orifice can be reused without requiring engine reconfiguration.

[0035] The gearbox orifice can be located above the cam gear (cam drive) mounted to the engine camshaft.

[0036] This position minimizes the amount of lubricating oil splashed towards the orifice.

[0037] The outflow portion of the ventilation path can enter the engine structure (e.g., a second portion of the gearbox separate from the first portion) via an outflow orifice in the engine structure. The outflow orifice can be located downstream of the outflow duct.

[0038] The routing unit can be installed adjacent to the outflow orifice in the engine structure.

[0039] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0040] The gearbox may include an outlet orifice.

[0041] A separate outlet may include an outflow portion of a ventilation path that extends from the crankcase to an engine structure outlet within the engine structure. The outflow portion may be configured to facilitate the flow of ventilation gases relative to the crankshaft axis of the engine within the axial range of the engine structure to suppress stagnation of leaking gases within the engine structure.

[0042] Advantageously, this configuration of the outflow section can help improve ventilation of leaks in the engine structure.

[0043] The gas pressure source may be located downstream of the crankcase. The ventilation system may include an oil pre-separator located upstream of the gas pressure source. The oil pre-separator may be configured to reduce the oil concentration in the exhaust gas delivered from the crankcase to the gas pressure source.

[0044] Advantageously, an oil pre-separator can help reduce the amount of oil in the exhaust gas flowing through the gas pressure source, which can help improve the efficiency of the gas pressure source and / or reduce damage to the gas pressure source.

[0045] The oil pre-separator can be a passive oil pre-separator.

[0046] A gas pressure source can be a pump.

[0047] Advantageously, using a pump as a gas pressure source allows for better control over the flow rate of the exhaust gas. Furthermore, providing the gas pressure source as a pump allows for greater flexibility in the pump's location within the engine.

[0048] The pump may include an impeller capable of rotating about an axis of rotation. The axis of rotation may be arranged to be substantially vertical in the normal operating orientation of the engine. For example, the axis of rotation of the impeller may be substantially parallel to the axis of one or more cylinders of the engine.

[0049] Advantageously, this arrangement of the impeller can help discharge oil and other liquids deposited from the exhaust gas from the pump.

[0050] The gas pressure source can be configured to generate a pressure in the crankcase below atmospheric pressure; optionally, in the range of -100 to -10 mbar relative to atmospheric pressure; for example, in the range of -80 to -20 mbar relative to atmospheric pressure.

[0051] Advantageously, generating a pressure below atmospheric pressure in the crankcase helps to prevent leaks from flowing from the crankcase to other parts of the engine via a path separated from the outlet.

[0052] The gas pressure source can be located downstream of the crankcase.

[0053] The ventilation system may include an oil separator configured to reduce the oil concentration in the exhaust gases delivered from the crankcase.

[0054] Advantageously, an oil separator can help remove oil from exhaust gases before they are released into the atmosphere or supplied to one or more cylinders of the engine. This can have environmental and / or emissions benefits, and can also reduce the amount of oil consumed by the engine, thus saving on replacement costs.

[0055] The engine may also include an oil passage arranged to deliver oil removed from the exhaust gases by an oil separator to the crankcase.

[0056] The oil separator can be a passive oil separator (e.g., a cyclonic oil separator).

[0057] Advantageously, this oil separator can help reduce parasitic losses in the engine.

[0058] The oil separator can be placed downstream of the gas pressure source.

[0059] Advantageously, this arrangement of the oil separator and the gas pressure source can facilitate the return of oil removed from the exhaust gas by the oil separator to the crankcase.

[0060] The oil separator can be installed to a gas pressure source.

[0061] An engine structure may include one or more cylinders. The engine may also include an intake system configured to supply air to the one or more cylinders. A ventilation system may be configured to deliver exhaust gases to the intake system for supply to the one or more cylinders via an outlet, such as an outflow portion via a ventilation path.

[0062] Advantageously, this configuration of the intake and ventilation systems can help improve engine fuel efficiency and / or reduce emissions.

[0063] The gas inlet may be in fluid communication with an air supply source. The intake system may include an intake passage arranged to deliver air from the gas inlet to the one or more cylinders. The ventilation system may be configured to draw air as ventilation gas from the intake passage into a ventilation path at a first location.

[0064] Advantageously, this configuration of the intake and ventilation systems eliminates the need for a separate dedicated gas inlet for the ventilation system.

[0065] The engine may also include a compressor along the intake passage. The first position may be located upstream of the compressor.

[0066] Advantageously, this configuration of the compressor and ventilation system can help reduce the pressure of the ventilation air flowing toward the crankcase along the ventilation path, and thus can help the gas pressure source generate a pressure below atmospheric pressure in the crankcase.

[0067] The compressor can be a turbocharger or a supercharger.

[0068] The gas pressure source can be configured to generate a lower pressure in the crankcase than the pressure at the compressor inlet.

[0069] Advantageously, this configuration of the intake and ventilation systems can help reduce fuel consumption and emissions.

[0070] The compressor can be configured to generate a pressure of -60 to 0 millibars relative to atmospheric pressure at the compressor inlet.

[0071] The ventilation system can be configured, for example, to discharge exhaust gas from a separate outlet to a second location in the intake passage via an outflow portion of the ventilation path. The second location can be located downstream of the first location relative to the intake passage.

[0072] Advantageously, this configuration of the intake and ventilation systems prevents exhaust gases emitted into the intake passage from flowing along the ventilation path to the crankcase.

[0073] The second position can be located upstream of the compressor.

[0074] The gas inlet may include a filter.

[0075] Advantageously, filters help prevent dust, debris, and other contaminants from entering the gearbox and crankcase.

[0076] The gaseous fuel can be hydrogen.

[0077] Advantageously, hydrogen produces fewer harmful emissions compared to some other gaseous fuels and can be produced from renewable energy sources.

[0078] The engine may include an engine structure including a crankcase. The ventilation system may include a gas pressure source and a ventilation path. The gas pressure source may be configured to deliver ventilation gas from a gas inlet to the crankcase along an inflow portion of the ventilation path. The gas pressure source may be configured to deliver a combination of ventilation gas and leaking gas, including gaseous fuel, as exhaust gas from the crankcase along an outflow portion of the ventilation path. The ventilation system may include a routing unit mounted adjacent to the engine structure. The routing unit may include: a housing; an inflow duct located in the inflow portion of the ventilation path; and an outflow duct located in the outflow portion of the ventilation path. The inflow and outflow ducts may be at least partially housed within the housing.

[0079] Advantageously, combining the inflow and outflow ducts into a single routing unit can help improve the enclosure of the ventilation system and simplify engine assembly.

[0080] The outflow duct may include an oil separator configured to reduce the oil concentration in the exhaust gas in the ventilation path.

[0081] Advantageously, this configuration of the outflow duct can help remove oil from the exhaust gases before they are discharged into the atmosphere or supplied to one or more cylinders of the engine.

[0082] The oil separator can be a passive oil separator.

[0083] Advantageously, this oil separator can help reduce parasitic losses in the engine.

[0084] The oil separator can be configured to change the flow direction of exhaust gas traveling along the ventilation path at least once (e.g., at least twice).

[0085] Advantageously, this configuration of the outflow conduit can help reduce the amount of oil in the exhaust gas flowing along the outflow conduit.

[0086] An oil separator may include a wall arranged to deflect exhaust gas traveling along a ventilation path.

[0087] Advantageously, this configuration of the outflow conduit can help reduce the amount of oil in the exhaust gas flowing along the outflow conduit.

[0088] The wall can be arranged to be substantially perpendicular to the flow direction of the exhaust gas immediately upstream of the wall.

[0089] The oil separator may include a textured surface arranged to contact the exhaust gas.

[0090] Advantageously, this configuration of the outflow conduit can help increase the surface area of ​​the outflow conduit in contact with the exhaust gas, which can help increase the deposition of oil and other liquids.

[0091] The oil separator may include a wall arranged to deflect exhaust gas traveling along a ventilation path. The wall may include a textured surface.

[0092] Advantageously, this configuration of the outflow conduit can help increase the surface area of ​​the wall in contact with the exhaust gas, which can help increase the deposition of oil and other liquids.

[0093] The wall can be arranged to be substantially perpendicular to the flow direction of the exhaust gas immediately upstream of the wall.

[0094] Oil separators can be configured to reduce the velocity of exhaust gases traveling along the ventilation path.

[0095] Advantageously, this configuration of the outflow conduit can help reduce the amount of oil in the exhaust gas flowing along the outflow conduit.

[0096] The outflow conduit may include a first section located upstream of the second section. The cross-sectional area of ​​the second section perpendicular to the flow direction may be larger than that of the first section to reduce the velocity of the discharged gas in the second section relative to the first section.

[0097] The outflow conduit may include an oil outlet for discharging oil separated from the exhaust gas by an oil separator.

[0098] The outflow conduit can be located upstream of the gas pressure source.

[0099] Advantageously, the outflow conduit can help reduce the amount of oil in the exhaust gas flowing through the gas pressure source, which can help improve the efficiency of the gas pressure source and / or reduce damage to the gas pressure source.

[0100] The inflow portion of the ventilation path can enter the engine structure via an inflow orifice in the engine structure. The inflow orifice can be located downstream of the inflow duct. The routing unit can be mounted adjacent to the inflow orifice to the engine structure.

[0101] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0102] The engine structure may include a gearbox, the gearbox including an inlet orifice.

[0103] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0104] The inlet can be located in the front-facing wall of the gearbox.

[0105] In liquid-fueled engines, an orifice is typically located at this position to transfer driving force from the gearbox to the fuel injection pump, so that the orifice can be reused without reconfiguring the engine.

[0106] The inlet can be located above the cam gear that is mounted to the engine camshaft.

[0107] This location helps to flush out floating leaks (such as hydrogen) from the top of the gearbox, which could otherwise become a trap for high concentrations of leaks. Additionally, it minimizes the amount of lubricating oil splashed toward the orifice.

[0108] The routing unit can cover the inflow orifice.

[0109] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0110] The outflow portion of the ventilation path can enter the engine structure via an outflow orifice in the engine structure. The outflow orifice can be located downstream of the outflow duct. The routing unit can be mounted adjacent to the outflow orifice to the engine structure.

[0111] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0112] The engine structure may include a gearbox, the gearbox including an outlet orifice.

[0113] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0114] The inflow and outflow conduits can be formed as a single unit.

[0115] Advantageously, the integral formation of the first and second ducts can help minimize the volume occupied by the routing unit, thereby contributing to improved encapsulation of the ventilation system.

[0116] The engine may include an engine structure, the engine structure including a crankcase. The ventilation system may include a gas pressure source and a ventilation path. The gas pressure source may be configured to deliver ventilation gas along the ventilation path from a gas inlet to the crankcase inlet. The gas pressure source may be configured to deliver a combination of ventilation gas and leaking gas, including gaseous fuel, as exhaust gas along an outflow portion of the ventilation path. The outflow portion may extend within the engine structure from the crankcase to an engine structure outlet. The outflow portion may be configured to facilitate the flow of ventilation gas relative to the crankshaft axis of the engine in an axial range within the engine structure to suppress stagnation of leaking gas within the engine structure.

[0117] Advantageously, this configuration of the outflow section can help improve ventilation of leaks in the engine structure.

[0118] The crankcase inlet and engine structure outlet can be located at or toward the first axial end of the engine structure. The outflow portion can be configured to facilitate the flow of ventilation gases toward the opposite second axial end of the engine structure.

[0119] The crankcase inlet can be located at or toward the first axial end of the engine structure. The engine structure outlet can be located at or toward the opposite second axial end of the engine structure. The outflow portion can be configured to facilitate the flow of ventilation gases toward the second axial end of the engine structure. Advantageously, this configuration of the engine structure outlet can help improve ventilation of leaks in the engine structure.

[0120] The engine structure may include a chamber protruding from the body of the engine structure. An outflow portion may extend from the body to the chamber. The chamber may include an engine structure outlet.

[0121] Advantageously, it has been found that this configuration reduces the local flow velocity of the ventilation gas and thus promotes the deposition of oil and other liquids entrained by the ventilation gas. This reduces the liquid concentration in the ventilation gas downstream of the engine structure outlet.

[0122] The chamber can have a larger flow cross-sectional area relative to the engine structure outlet.

[0123] Advantageously, it has been found that this configuration reduces the local flow velocity of the ventilation gas and thus promotes the deposition of oil and other liquids entrained by the ventilation gas. This reduces the liquid concentration in the ventilation gas downstream of the engine structure outlet.

[0124] The flow cross-sectional area of ​​the chamber upstream of the engine structure outlet and / or adjacent to the engine structure outlet can be larger than the flow cross-sectional area of ​​the engine structure outlet.

[0125] In normal engine operation orientation, the chamber can be configured such that the exhaust gas travels generally upwards before passing through the engine structure outlet.

[0126] Advantageously, this configuration has been found to promote the deposition of oil and other liquids entrained by the ventilation gases. This reduces the liquid concentration in the ventilation gases downstream of the engine structure outlet.

[0127] The chamber can protrude upwards from the main body of the engine structure.

[0128] The engine structure outlet may include an outlet conduit passing through the outer peripheral wall of a defined chamber. The outlet conduit may have a first open end and a second open end in fluid communication with each other. The first open end may be inside the chamber and spaced apart from the outer peripheral wall.

[0129] Advantageously, this configuration has been found to promote the deposition of oil and other liquids entrained by the ventilation gases. This reduces the liquid concentration in the ventilation gases downstream of the engine structure outlet.

[0130] The second opening can be outside the chamber and spaced apart from the outer peripheral wall.

[0131] The length of the outlet catheter between the first opening end and the outer peripheral wall can be greater than 20% of the corresponding width of the chamber, for example, greater than 30% of the corresponding width of the chamber, for example, greater than 40% of the corresponding width of the chamber, for example, greater than 50% of the corresponding width of the chamber.

[0132] Advantageously, this configuration has been found to promote the deposition of oil and other liquids entrained by the ventilation gases. This reduces the liquid concentration in the ventilation gases downstream of the engine structure outlet.

[0133] The engine structure may include an oil filling conduit for receiving oil to replenish the engine. The oil filling conduit may include a chamber.

[0134] Oil-filled ducts can have a relatively large flow cross-sectional area, which helps to reduce the flow velocity of ventilation gas passing through them.

[0135] The engine structure may also include a rocker arm cover. An outlet portion leads from the crankcase to the rocker arm cover. The rocker arm cover can be configured to facilitate the flow of ventilation gases across the axial range of the engine structure.

[0136] The oil filling conduit can protrude from the rocker cover body.

[0137] The oil filling conduit can be located on the top side of the rocker cover.

[0138] Oil filling conduits can protrude from the (e.g., top) surface of the engine structure body (e.g., rocker cover).

[0139] The rocker arm cover may include a cavity and a channel, the cavity for receiving one or more rocker arms. An outlet portion may sequentially pass through the crankcase, at least through the cavity and the channel, and then through an engine structure outlet. The channel may be configured to facilitate the flow of ventilation gases across the axial range of the engine structure.

[0140] Advantageously, this configuration helps to promote cross-flow of gas throughout the engine structure without requiring moving parts.

[0141] The rocker cover may include an engine structure outlet.

[0142] The channel may include a portion located at or downstream of a first axial end of the engine structure. The channel may also include an upstream portion that is closer to a corresponding second axial end of the engine structure than the downstream portion. The upstream portion may be more open into the cavity than the downstream portion.

[0143] Advantageously, this configuration helps to promote cross-flow of gas throughout the engine structure without requiring moving parts.

[0144] The upstream section may include multiple openings. Each opening provides a pathway for the exhaust gas from the cavity to the channel.

[0145] The downstream section may include one or more openings. Each opening provides a pathway for the exhaust gas from the cavity to the channel.

[0146] Advantageously, providing one or more openings to the downstream section can help suppress the formation of stagnant zones in the exhaust gas toward the first axial end.

[0147] The upstream portion may extend 5% to 50% of the width of the cavity between the first axial end and the second axial end; optionally, extend the width by 10% to 50%; optionally, extend the width by 20% to 50%.

[0148] The channel can extend roughly parallel to the crankshaft axis.

[0149] The channel can be adjacent to the inner top side of the rocker cover.

[0150] Advantageously, this configuration can help prevent oil from entering the channel from the rocker cover and thus being transported along the ventilation path.

[0151] The rocker arm cover may include a body and a component such as a plate. The component may be mounted to the inner top side of the body. A channel may be formed between the inner top side of the body and the component.

[0152] Advantageously, this configuration can help simplify engine assembly.

[0153] The main body can be formed as a single, integral material part (e.g., via casting or pressing processes).

[0154] The engine structure may also include a cylinder bank and / or a cylinder head. Outflow portions may pass within the cylinder bank and / or cylinder head. The outflow portions may be configured to facilitate the flow of ventilation gases across the axial range of the cylinder bank and / or cylinder head to prevent leakage gas from stagnating therein.

[0155] The outflow portion can be completely located within the engine structure.

[0156] The engine may include an engine structure comprising: a crankcase; and an oil reservoir located below the crankcase. A ventilation system may include a gas pressure source configured to deliver leaks, including gaseous fuel, as exhaust gases from the crankcase. The ventilation system may include a first oil separator configured to reduce the oil concentration in the exhaust gases. The ventilation system may be configured such that, during operation, the gas pressure in the crankcase is higher than the gas pressure in the first oil separator. The engine may include a first exhaust duct arranged to deliver oil removed from the exhaust gases by the first oil separator to the oil reservoir. The first exhaust duct may be configured to maintain a head of oil (oil column, oil column height) applying hydrostatic pressure on the oil in the oil reservoir to inhibit the delivery of gases from the crankcase to the oil separator via the first exhaust duct during operation.

[0157] Advantageously, this configuration of the discharge duct allows oil removed from the exhaust gases by the first oil separator to be continuously discharged into the oil reservoir, despite the pressure difference between the crankcase and the oil separator. Therefore, it is not necessary to alter the operation of the ventilation system (e.g., to balance the pressure in the crankcase and the oil separator) to allow the removed oil to be discharged into the oil reservoir.

[0158] A first end of the first discharge conduit may be connected to a first oil separator. A second end of the first discharge conduit may be connected to an oil reservoir. The first discharge conduit may be configured such that oil flows from the first end to the second end without obstruction by moving parts.

[0159] Advantageously, this configuration of the first exhaust duct helps reduce engine maintenance requirements.

[0160] The first end of the first drain pipe can be connected to the first oil separator. The second end of the first drain pipe can be connected to the oil reservoir. The first end can be at the level of the crankcase or above the crankcase.

[0161] Advantageously, this position of the first end can help ensure that the height of the oil that can be contained in the first discharge duct provides a sufficient hydrostatic head to balance the pressure difference between the crankcase and the oil separator.

[0162] The engine structure may include a cylinder bank above the crankcase. The first end may be at the level of the cylinder bank or above the cylinder bank.

[0163] Advantageously, this installation position of the first oil separator can help ensure that the height of the oil that can be contained in the first discharge duct provides sufficient hydrostatic head to balance the pressure difference between the crankcase and the oil separator.

[0164] The engine structure may include a gearbox. A first oil separator may be mounted adjacent to the gearbox.

[0165] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0166] The first discharge conduit can be arranged to deliver oil adjacent to the bottom of the oil reservoir.

[0167] Advantageously, this configuration can help reduce the risk that the oil level in the tank may drop below the outlet of the first discharge duct, which could cause gas to bypass the oil and travel from the crankcase along the first discharge duct to the first oil separator.

[0168] The first exhaust duct can be located outside the engine structure.

[0169] Advantageously, this configuration can help simplify engine assembly and maintenance.

[0170] The gas pressure source can be located downstream of the crankcase. The first oil separator can be located upstream of the gas pressure source.

[0171] Advantageously, arranging the gas pressure source downstream of the crankcase can help generate a pressure below atmospheric pressure in the crankcase, which helps to suppress leaks from the crankcase to other engine components that are separate from the ventilation system.

[0172] In addition, the first oil separator can help reduce the amount of oil in the exhaust gas flowing through the gas pressure source, which can help improve the efficiency of the gas pressure source and / or reduce damage to the gas pressure source.

[0173] The ventilation system may include a second oil separator configured to reduce the oil concentration in the exhaust gases. The ventilation system may be configured such that the gas pressure in the crankcase during operation is lower than the gas pressure in the second oil separator. The engine may include a second exhaust duct separate from a first exhaust duct, the second exhaust duct being arranged to deliver oil removed from the exhaust gases by the second oil separator to a portion of the engine structure leading to an oil reservoir.

[0174] The second oil separator can be a passive (e.g., cyclone) oil separator.

[0175] The gas pressure source can be located downstream of the crankcase. The second oil separator can be located downstream of the gas pressure source.

[0176] The first oil separator can be a passive oil separator.

[0177] Advantageously, this oil separator can help reduce parasitic losses in the engine.

[0178] A gas pressure source can be a pump.

[0179] Advantageously, using a pump as a gas pressure source allows for better control over the flow rate of the exhaust gas. Furthermore, providing the gas pressure source as a pump allows for greater flexibility in the pump's location within the engine.

[0180] The gaseous fuel can be hydrogen.

[0181] Advantageously, hydrogen produces fewer harmful emissions compared to some other gaseous fuels and can be produced from renewable energy sources.

[0182] The engine may include an engine structure including a crankcase. A ventilation system may be configured to deliver leaks, including gaseous fuel, as exhaust gases from the crankcase. The ventilation system may include an oil separator configured to reduce the oil concentration in the exhaust gases. The oil separator may include: a separator portion configured to separate oil from the exhaust gases; and an outlet portion mounted to the separator portion. The outlet portion may include an oil outlet in fluid communication with the separator portion for discharging the separated oil from the oil separator. The engine structure may include an inlet portion including an oil inlet. The outlet portion may be mounted to the inlet portion such that oil exiting the oil outlet enters the oil inlet, and such that the separator portion is mounted to the engine structure.

[0183] Advantageously, installing the outlet portion of the oil separator to the inlet portion of the engine structure allows oil leaving the oil outlet to enter the oil inlet. Furthermore, installing the separator portion to the engine structure can help improve the enclosure of the ventilation system and simplify engine assembly, since no separate drain hose is required between the oil separator and the engine structure.

[0184] One of the outlet and inlet portions may include a male portion (convex portion) comprising a corresponding oil outlet or inlet. The other of the outlet and inlet portions may include a corresponding female portion (concave portion) comprising a corresponding oil outlet or inlet. The male portion may be received within the female portion.

[0185] Advantageously, the male and female portions can provide positioning features that help simplify engine assembly.

[0186] The male portion may include a male thread, and the female portion may include a corresponding female thread. The outlet portion may be installed to the inlet portion via the engagement of the male and female threads.

[0187] Advantageously, this configuration of the yang and yin sections can help reduce the space envelope of the exit and entrance sections, because no space is needed for additional fixing devices.

[0188] The outlet portion may include a male portion, and the inlet portion may include a female portion. The male portion may be able to rotate relative to the separator portion about the helical axis of the male portion to engage the male thread and the female thread.

[0189] Advantageously, this configuration of the male and female parts can help simplify engine assembly.

[0190] The outlet portion may include a recess that engages with a tool such as a screwdriver or Allen wrench to allow the male portion to rotate about its helical axis.

[0191] Advantageously, the recess can help simplify engine assembly.

[0192] The recess can be opposite the oil outlet.

[0193] At least a portion of the separator section and at least a portion of the outlet section can be formed as a single integral material piece, such that the outlet section is installed to the separator section.

[0194] Advantageously, this configuration of the oil separator helps simplify engine assembly.

[0195] The separator section may include a truncated conical portion. At least a portion of the outlet section and the truncated portion (e.g., the apex of the truncated portion) may be formed as a single integral piece of material.

[0196] The separator section can be adjacent to the inlet section.

[0197] Advantageously, this engine configuration can reduce the space required for the oil separator and thus help improve the enclosure of the ventilation system.

[0198] The outlet section can be basically arranged below the separator section.

[0199] Advantageously, the outlet section is positioned below the separator section so that the separated oil can flow from the separator section to the oil outlet under gravity, thus eliminating the need for an external power source.

[0200] The separator section can be elongated. The longitudinal axis of the separator section can be substantially perpendicular to the axis of the oil outlet.

[0201] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0202] The maximum length of the outlet section can be less than the maximum length of the separator section.

[0203] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0204] The volume of the outlet section can be smaller than that of the separator section.

[0205] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0206] The engine may also include a sealing device between the outlet and inlet sections. The sealing device can be configured to suppress oil leakage traveling from the oil outlet toward the oil inlet.

[0207] Sealing devices may include sealing components, such as O-rings.

[0208] The oil separator can be a passive oil separator.

[0209] Advantageously, this oil separator can help reduce parasitic losses in the engine.

[0210] The oil separator can be a cyclone oil separator, which is configured to form a vortex in the exhaust gas to separate oil therefrom.

[0211] The separator section may include a truncated conical section with a vertex. The outlet section may be mounted to the vertex.

[0212] The crankcase may include an oil inlet.

[0213] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0214] The ventilation system can be configured such that the gas pressure in the crankcase is lower than the gas pressure in the oil separator.

[0215] Advantageously, this pressure difference can help to transport the separated oil from the separator section to the oil inlet.

[0216] The ventilation system may include a gas pressure source configured to deliver exhaust gases from the crankcase. An oil separator may be located downstream of the gas pressure source.

[0217] A gas pressure source can be a pump.

[0218] The gaseous fuel can be hydrogen.

[0219] The engine may include an engine structure including a crankcase. A ventilation system may include an outflow ventilation path and a gas pressure source configured to deliver leaked gas, including gaseous fuel, as exhaust gas from the crankcase along the outflow ventilation path. The outflow ventilation path may include an external duct outside the engine structure. The engine may include a heat transfer device configured to transfer heat generated by combustion from the engine structure to at least a portion of the external duct to heat the exhaust gas delivered therein.

[0220] Advantageously, transferring heat to the external duct helps prevent water vapor in the exhaust gases from freezing, which could clog the duct and damage ventilation system components. Furthermore, by utilizing the heat generated by combustion, parasitic losses in the engine can be reduced.

[0221] The heat transfer device may include a heat transfer path and a fluid pressure source, such as a pump. The fluid pressure source may be configured to deliver heat transfer fluid along the heat transfer path from the engine structure to at least a portion of the external duct to transfer heat generated during combustion.

[0222] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0223] The heat transfer device may also include a heat exchanger, such as a radiator, for cooling engine structures. The heat exchanger may be located in the heat transfer path.

[0224] Advantageously, this configuration of the heat transfer device eliminates the need for separate piping for the engine cooling system and the external duct heating system.

[0225] The heat transfer path can be a closed path. The heat transfer path can exit the engine structure via a first orifice in the engine structure. The heat transfer path can pass through at least a portion of an external duct. Then, the heat transfer path can enter the engine structure via a second orifice in the engine structure.

[0226] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0227] The engine structure may include a cylinder bank and a cylinder head. At least a portion of an external duct may be adjacent to one or both of the cylinder head and the cylinder bank. Each of the first and second orifices may be located in the cylinder head or the cylinder bank.

[0228] Advantageously, this configuration of the heat transfer device helps to reduce the length of the heat transfer path outside the engine structure, and thus helps to improve the encapsulation of the heat transfer device.

[0229] The heat transfer path may include a conduit that at least partially surrounds at least a portion of an external conduit for transferring heat generated by combustion from a heat transfer fluid in the conduit to at least a portion of the conduit.

[0230] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0231] The conduit may be an annular conduit that substantially surrounds at least a portion of the external conduit.

[0232] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0233] The heat transfer device may include a passive heat transfer device configured to transfer heat generated by combustion from the engine structure to at least a portion of the external duct.

[0234] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts, while minimizing the parasitic losses of the engine.

[0235] Passive heat transfer devices may include one or more heat pipes.

[0236] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0237] A passive heat transfer device may include a heat transfer member connected to a portion of the engine structure and at least a portion of an external duct. The heat transfer member may be configured to transfer heat generated by combustion from a portion of the engine structure to at least a portion of the external duct.

[0238] The aforementioned portion of the engine structure may be formed of a first material. The heat transfer components may be formed of a second material with a thermal conductivity greater than or equal to that of the first material.

[0239] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0240] The passive heat transfer device may at least partially surround at least a portion of an external conduit.

[0241] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0242] A passive heat transfer device may include an annular portion substantially surrounding at least a portion of the conduit.

[0243] Advantageously, this configuration of the heat transfer device helps to more effectively transfer the heat generated by combustion from the engine structure to the external ducts.

[0244] A portion of the outflow ventilation path extending between the crankcase and the external duct can be located within the engine structure.

[0245] Advantageously, this configuration of the outflow ventilation path helps prevent water and water vapor in the exhaust gas from freezing.

[0246] The gas pressure source can be located outside the engine structure. An external duct can lead to the gas pressure source.

[0247] A portion of the outflow ventilation path downstream of the external duct can pass within the engine structure.

[0248] Advantageously, this configuration of the outflow ventilation path helps prevent water and water vapor in the exhaust gas from freezing.

[0249] The engine may also include thermal insulation material that at least partially covers the external ducts to increase their thermal insulation properties.

[0250] The gaseous fuel can be hydrogen.

[0251] A second aspect of this teaching provides an oil separator for a crankcase ventilation system, the oil separator being configured to discharge leaks from the crankcase containment. The oil separator is configured to reduce the oil concentration in the exhaust gases. The oil separator includes: a separator portion configured to separate oil from the exhaust gases; and an outlet portion mounted to the separator portion. The outlet portion includes an oil outlet in fluid communication with the separator portion for discharging the separated oil from the oil separator. The outlet portion is configured to be mounted to an inlet portion of an engine structure, such that oil exiting the oil outlet enters the inlet portion, and such that the separator portion is mounted to the engine structure.

[0252] One of the outlet and inlet portions may include a male portion, which includes a corresponding oil outlet or oil inlet. The other of the outlet and inlet portions may include a corresponding female portion, which includes a corresponding oil outlet or oil inlet. The male portion may be received within the female portion.

[0253] Advantageously, the male and female portions can provide positioning features that help simplify engine assembly.

[0254] The male portion may include a male thread, and the female portion may include a corresponding female thread. The outlet portion may be installed to the inlet portion via the engagement of the male and female threads.

[0255] Advantageously, this configuration of the yang and yin sections can help reduce the spatial range of the outlet and inlet sections, as space can be eliminated for additional fixing devices.

[0256] The outlet portion may include a male portion, and the inlet portion may include a female portion. The male portion may be able to rotate relative to the separator portion about the helical axis of the male portion to engage the male thread and the female thread.

[0257] Advantageously, this configuration of the male and female parts can help simplify engine assembly.

[0258] The outlet portion may include a recess that engages with a tool such as a screwdriver or Allen wrench to allow the male portion to rotate about its helical axis.

[0259] Advantageously, the recess can help simplify engine assembly.

[0260] The recess can be opposite the oil outlet.

[0261] At least a portion of the separator section and at least a portion of the outlet section can be formed as a single integral material piece, such that the outlet section is installed to the separator section.

[0262] Advantageously, this configuration of the oil separator helps simplify engine assembly.

[0263] The separator section may include a truncated conical portion. At least a portion of the outlet section and the truncated portion (e.g., the apex of the truncated portion) may be formed as a single integral piece of material.

[0264] The separator section can be adjacent to the inlet section.

[0265] Advantageously, this engine configuration can reduce the space required for the oil separator and thus help improve the enclosure of the ventilation system.

[0266] The outlet section can be basically arranged below the separator section.

[0267] Advantageously, the outlet section is positioned below the separator section so that the separated oil can flow from the separator section to the oil outlet under gravity, thus eliminating the need for an external power source.

[0268] The separator section can be elongated. The longitudinal axis of the separator section can be substantially perpendicular to the axis of the oil outlet.

[0269] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0270] The maximum length of the outlet section can be less than the maximum length of the separator section.

[0271] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0272] The volume of the outlet section can be smaller than that of the separator section.

[0273] Advantageously, this configuration can help improve the enclosure of the ventilation system.

[0274] The oil separator may also include a sealing device between the outlet and the inlet. The sealing device can be configured to prevent oil leakage from the oil outlet toward the oil inlet.

[0275] Sealing devices may include sealing components, such as O-rings.

[0276] The oil separator can be a passive oil separator.

[0277] Advantageously, this oil separator can help reduce parasitic losses in the engine.

[0278] The oil separator can be a cyclone oil separator, which is configured to form a vortex in the exhaust gas to separate oil therefrom.

[0279] The separator section may include a truncated conical section with a vertex. The outlet section may be mounted to the vertex.

[0280] It should be understood that the features of the first and second aspects can be combined with each other. Attached Figure Description

[0281] Embodiments are now disclosed by way of example only, with reference to the accompanying drawings, in which: Figure 1 An isometric view of an internal combustion engine according to an embodiment is shown; Figure 2 It shows that it contains Figure 1 A side view of an exemplary working machine with an internal combustion engine; Figure 3 A simplified block diagram of an internal combustion engine crankcase ventilation system is shown. Figure 4 It shows Figure 1 Isometric view of the pump, oil separator, and routing unit of the crankcase ventilation system of an internal combustion engine; Figure 5 It shows the relationship with Figure 1 Other components of the internal combustion engine are isolated. Figure 4 An isometric view of the pumps and routing units; Figure 6 It shows the way Figure 5 The diagram shows a cross-sectional view of the routing unit taken by section X6-X6. Figure 7 It shows the way Figure 5 The diagram shows a cross-sectional view of the routing unit captured by section X7-X7. Figure 8 It shows the way Figure 5 The diagram shows a cross-sectional view of the routing unit captured by section X8-X8. Figure 9 It shows the way Figure 1 The cross-sectional view of the internal combustion engine shown is taken from section X4-X4. Figure 10 It shows the way Figure 1 The cross-sectional view of the internal combustion engine shown is taken from section X1-X1. Figure 11 It shows the way Figure 1 The cross-sectional view of the internal combustion engine shown is taken from section X2-X2. Figure 12 It shows the way Figure 1 The cross-sectional view of the rocker arm cover of the internal combustion engine shown is taken from section X1-X1. Figure 13 It shows the way Figure 1 The cross-sectional view of the rocker arm cover of the internal combustion engine shown is taken from section X5-X5. Figure 14 It shows the way Figure 13The cross-sectional view of the rocker arm cover taken by section X9-X9 is shown in the figure. Figure 15 It shows Figure 1 Rear isometric view of the oil separator of an internal combustion engine; Figure 16 It shows the way Figure 1 The cross-sectional view of the internal combustion engine shown is taken from section X3-X3. Figure 17 It shows Figure 1 Side view of the exhaust duct and fuel reservoir of an internal combustion engine; Figure 18 It shows Figure 17 A simplified diagram of the discharge duct and oil reservoir; Figure 19 It shows Figure 1 A front isometric view of the oil separator of an internal combustion engine; Figure 20a It shows the way Figure 4 The cross-sectional view of the oil separator and engine structure of the internal combustion engine shown is taken from section X10-X10. Figure 20b It shows the connection with Figure 4 The cross-sectional view shown is a cross-sectional view of another embodiment of the oil separator and engine structure of an internal combustion engine, with the cross-section X10-X10 corresponding to that shown. Figure 21 It shows Figure 1 An isometric view of an embodiment of a heat transfer device for an internal combustion engine; Figure 22 It shows Figure 21 A simplified block diagram of a heat transfer device; Figure 23 It shows Figure 21 An exemplary heat transfer path of a heat transfer device; Figure 24 It shows Figure 1 A simplified schematic diagram of an embodiment of a heat transfer device for an internal combustion engine; Figure 25 A cross-sectional view of a rocker arm cover according to another embodiment is shown, which is consistent with... Figure 12 The view shown corresponds to the view shown. Figure 26 It is along Figure 25 The view shown is a section X12-X12; and Figure 27 yes Figure 25 Isometric view of the top of the rocker arm cover. Detailed Implementation

[0282] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and teachings. However, those skilled in the art will understand that the teachings can be practiced without these specific details or with known equivalents having these specific details; the teachings are not limited to the described embodiments; and the teachings can be practiced in various alternative embodiments. It should also be understood that well-known methods, processes, components, and systems may not be described in detail.

[0283] Figure 1 An internal combustion engine 100 according to an embodiment is shown. Engine 100 is a gas-fueled engine configured to be powered by a gaseous fuel such as hydrogen, compressed natural gas (CNG), biogas, etc. In the illustrated embodiment, engine 100 is powered by hydrogen.

[0284] Engine 100 can be used as work machine 10 (see...) Figure 2 The description refers to a backhoe loader, but it can also be a prime mover in a telescopic loader, forklift, wheeled loader, dump truck, excavator, or tractor. Such a work machine 10 is suitable for use in off-highway industries such as agriculture and construction. In these industries, they are typically configured to perform tasks such as digging, load handling, harvesting, or planting crops. The engine 100 can also be used in a genset, a self-sufficient unit that provides electricity in an off-grid location. Therefore, the engine 100 is typically required to have certain characteristics, such as high torque output over a wide range of engine speeds, where peak torque occurs at relatively low engine speeds, unlike, for example, light passenger vehicles. In off-highway applications, this provides a "torque reserve," which allows the work machine 10 to continue operating when encountering increased loads or resistance to the work operation (e.g., an excavator encountering particularly hard clods of soil to be excavated).

[0285] The engine 100 includes an engine structure 102, which includes a crankcase 104, an oil reservoir 105, a cylinder head 106, a rocker arm cover 107, a cylinder bank 108, and a gearbox 109.

[0286] Cylinder assembly 108 includes one or more cylinders 112; in this embodiment, there are four (see...). Figure 10The cylinder head 106 is mounted to the cylinder bank 108 to connect to one or more cylinders 112. The cylinder head 106 includes one or more intake ports (not shown) for supplying air to each cylinder 112, and one or more exhaust ports (not shown) for discharging combustion gases from each cylinder 112. Each intake port is selectively opened and closed by an intake valve (not shown), and each exhaust port is selectively opened and closed by an exhaust valve (not shown).

[0287] In this embodiment, the engine 100 includes a hydrogen fuel delivery system through which hydrogen fuel can be delivered from a pressurized fuel tank 12 ( Figure 2 The hydrogen is injected directly into each cylinder 112. The fuel tank 12 is typically rated at a pressure exceeding 35 MPa, and the hydrogen pressure can be gradually reduced before being introduced into the cylinder 112. In other embodiments, the engine 100 is a port fuel injection (PFI) engine, and one or more intake ports also supply hydrogen fuel to each cylinder 112.

[0288] In alternative embodiments (not shown), engine 100 may have more or fewer cylinder assemblies, such as 2, 3, 6, or 8. Additionally, in other embodiments, cylinders 112 may be oriented in a "V" shape or horizontally opposed boxer configuration, rather than in a straight line as in the disclosed embodiments.

[0289] refer to Figure 11 The engine 100 includes a valve train 200, which includes a camshaft 202 and a rocker arm 204. The rocker arm is arranged to open and close each intake valve and each exhaust valve via rotation of the camshaft 202. The camshaft 202 is mounted to a cylinder bank 108. The rocker arm 204 is mounted to a cylinder head 106. Movement of the camshaft 202 is transmitted to the rocker arm 204 via a pushrod 206 extending between the cylinder bank 108 and the cylinder head 106. A rocker arm cap 107 is mounted to the cylinder head 106 and houses the rocker arm 204.

[0290] like Figure 10 As shown, each cylinder 112 receives a piston 113, which is capable of translational movement within the cylinder 112. During operation of the engine 100, the translational movement of each piston 113 is converted into rotational movement of the crankshaft 111. The crankshaft 111 rotates about crankshaft axis A. The crankcase 104 houses the crankshaft 111.

[0291] In the illustrated embodiment, the cylinder bank 108 and crankcase 104 are partially integrally formed. Specifically, the engine is bedplate type, wherein the upper portion 104a of the crankcase 104 is integrally and monolithically cast with the cylinder bank 108. The lower portion 104b is manufactured as a separate casting, wherein the joint between the upper portion 104a and the lower portion 104b is located at the midpoint of the crankshaft bearing journal. In an alternative embodiment, the cylinder bank 108 and crankcase 104 may be entirely a single casting (not shown), i.e., as a single integral and monolithic material, or as two or more completely separate castings (not shown). In these cases, a separate bearing cap can be used to mount the crankshaft to the crankcase 104.

[0292] Oil reservoir 105 (also commonly referred to as oil sump) stores oil used in the engine lubrication system. Oil reservoir 105 is mounted to crankcase 104 below crankcase 104. Oil reservoir 105 opens to crankcase 104 and is arranged to collect lubricating oil discharged from the rest of engine 100.

[0293] In this embodiment, the total displacement of engine 100 is 4.4 liters (i.e., 1.1 liters per cylinder). In engines used for off-highway applications, each cylinder can typically have a displacement between 0.75 and 1.5 liters. This displacement is relatively high compared to passenger vehicle engines, but it is suitable for providing the aforementioned operating characteristics.

[0294] Gearbox 109 is mounted to one or both of cylinder bank 108 and crankcase 104. Gearbox 109 laterally protrudes from one or both of cylinder bank 108 and crankcase 104. Gearbox 109 houses gear assembly 339 (in... Figure 9 As shown in the diagram, the gear assembly is configured to transmit rotational motion of the crankshaft 111 to the camshaft 202 for operation of the rocker arm 204. The gearbox 109 is in fluid communication with the crankcase 104.

[0295] Further reference Figure 3 The engine 100 includes an intake system 115 configured to supply air to one or more cylinders 112 for combustion. For clarity, Figure 1 The intake system 115 is omitted. In the illustrated embodiment, the intake system 115 is configured to supply air to the cylinder head 106 for delivery to the cylinder 112 via a corresponding intake port.

[0296] The intake system 115 includes an intake passage 140 (composed of...) Figure 3(Represented by double lines in the diagram), the intake passage 140 is arranged to deliver air from an upstream air inlet 118 to a downstream cylinder 112. The air inlet 118 may include an air filter. The intake passage 140 is configured to supply air to the cylinder 112 via the cylinder head 106 for combustion.

[0297] During operation of engine 100, some gaseous fuel and air introduced into each cylinder 112, along with combustion gases formed within the cylinder 112, flow out of the combustion chamber as “leakage” following the path indicated by arrow 205, through piston 113, and into crankcase 104. Leakage may also accumulate in gearbox 109, which is in fluid communication with crankcase 104. For example, if gaseous fuel and therefore leakage are more buoyant than air (e.g., hydrogen), a high concentration of leakage may accumulate at the top of gearbox 109, which is inherently shaped to act as a trap.

[0298] The engine 100 includes a ventilation system 110 configured to ventilate leaks from the crankcase 104 and gearbox 109.

[0299] Figure 3 A simplified diagram of a ventilation system 110 according to an embodiment is shown. The ventilation system 110 includes a ventilation path 116 (in... Figure 3 (Indicated by a dashed line), ventilation gas (air in this embodiment) is delivered from the intake system 115 to the crankcase 104 from the ventilation path inlet to dilute the concentration of leaks in the crankcase 104. This portion of the ventilation path 116 located upstream of the crankcase 104 is referred to as the inlet portion 125. The term "ventilation gas" is used to distinguish it from the air supplied to one or more cylinders 112 for combustion.

[0300] The ventilation system 110 is configured to draw air as ventilation gas from the intake passage 140 into the ventilation path 116 at a first position 140a at the inlet of the defined ventilation path.

[0301] The ventilation system 110 is also configured to deliver diluted leaked gas (hereinafter referred to as "exhaust gas") from the crankcase 104 to an outlet via ventilation path 116. This portion of ventilation path 116 located downstream of the crankcase 104 is referred to as outflow portion 126.

[0302] The ventilation system 110 is configured to discharge exhaust gas from the crankcase 104 to a second position 140b of a defined ventilation path outlet of the intake passage 140. The second position 140b is located downstream of the first position 140a relative to the intake passage 140.

[0303] The ventilation system 110 also includes a gas pressure source 114 located within the ventilation path 116. The gas pressure source 114 is configured to deliver ventilation gas from a first position 140a to the gearbox 109 and then to the crankcase 104 along the inflow portion 125 of the ventilation path 116. As will be discussed in more detail below, in the illustrated embodiment, the gas pressure source 114 delivers ventilation gas from the first position 140a to a first portion 109a of the gearbox 109 and then to the crankcase 104.

[0304] The gas pressure source 114 is also configured to deliver a combination of ventilation gas and leakage gas (which includes gaseous fuel) as exhaust gas from the crankcase 104 and gearbox 109 along the outflow portion 126 of the ventilation path 116 to the second position 140b.

[0305] Advantageously, delivering ventilation gas from the first position 140a via gearbox 109 to crankcase 104 helps to expel and remove leaking gas from gearbox 109. This reduces the risk of leaking gas burning within gearbox 109. Furthermore, it reduces the exposure of components in gearbox 109 (e.g., gear assembly 339) to leaking gas, which can reduce damage to these components due to exposure to hydrogen-containing leaking gas (e.g., via hydrogen embrittlement).

[0306] In the illustrated embodiment, the gas pressure source 114 is a pump 114 or a blower. In alternative embodiments (not shown), any suitable gas pressure source can be used. For example, in some embodiments, the gas pressure source 114 may be provided by a compressor or turbine (e.g., a compressor or turbine stage of a turbocharger) in the intake system 115 / exhaust system, which is in fluid communication with the ventilation system 110.

[0307] Pump 114 is configured to generate a pressure in crankcase 104 that is below atmospheric pressure in the range of -100 to -10 mbar relative to atmospheric pressure; for example, in the range of -80 to -20 mbar relative to atmospheric pressure. In the illustrated embodiment, pump 114 is arranged downstream of crankcase 104, in the outflow portion 126 of ventilation path 116.

[0308] In an alternative embodiment (not shown), pump 114 may be configured to generate any suitable pressure below atmospheric pressure in crankcase 104. In other embodiments, pump 114 may be configured to generate pressure above atmospheric pressure in crankcase 104. For example, pump 114 may be located upstream of crankcase 104, in the inflow portion 125 of ventilation path 116.

[0309] Ventilation system 110 includes a first oil separator 304 upstream of pump 114, which will also be referred to as "oil pre-separator 304". Oil pre-separator 304 is configured to reduce the oil concentration in the exhaust gas delivered from crankcase 104 to pump 114. Oil pre-separator 304 is located in outflow section 126.

[0310] Further reference Figure 4 and Figure 5 The ventilation system 110 includes a routing unit 300 mounted adjacent to the engine structure 102. As will be discussed in more detail below, the routing unit 300 includes: an inflow duct 302 located in the inflow portion 125 of the ventilation path 116; an outflow duct 304 located in the outflow portion 126 of the ventilation path 116; and a housing 306. The inflow duct 302 and the outflow duct 304 are at least partially housed within the housing 306. Advantageously, combining the inflow duct 302 and the outflow duct 304 in a single routing unit 300 helps improve the encapsulation of the ventilation system 110 and helps simplify the assembly of the engine 100.

[0311] In the illustrated embodiment, the outflow conduit 304 is an oil pre-separator 304. In an alternative embodiment (not shown), the outflow conduit 304 may additionally or alternatively include a separate oil pre-separator.

[0312] As discussed further below, the oil pre-separator 304 of this embodiment is a passive oil separator. A "passive oil separator" is defined as an oil separator that does not require an external power source to reduce the oil concentration in the exhaust gas flowing through it. In alternative embodiments, the ventilation system 110 may include any suitable active or passive oil pre-separator.

[0313] In the illustrated embodiment, the routing unit 300 is mounted adjacent to the gearbox 109. (See reference...) Figure 4 and Figure 5 The routing unit 300 is mounted to the gearbox 109 such that the main surface 305 of the housing 306 contacts the wall 318 of the gearbox 109. This contact increases heat transfer from the engine structure 102 to the routing unit 300, as discussed in more detail below, which helps to prevent water vapor in the exhaust gas from freezing in the outflow duct 304. Furthermore, this mounting of the routing unit 300 to the gearbox 109 helps to improve the encapsulation of the ventilation system 110.

[0314] In an alternative embodiment (not shown), the routing unit 300 may be mounted adjacent to any suitable part of the engine structure 102 (e.g., crankcase 104 or cylinder bank 108).

[0315] Return to reference Figure 3The ventilation system 110 includes a second oil separator 130, which will also be referred to as "oil separator 130," configured to reduce the oil concentration in the exhaust gases delivered from the crankcase 104. Oil separator 130 is a passive oil separator. In the illustrated embodiment, oil separator 130 is a cyclone oil separator, which will be discussed in more detail below. In alternative embodiments (not shown), oil separator 130 can be any suitable active or passive oil separator. Oil separator 130 is located in the outflow portion 126. Oil separator 130 is arranged downstream of pump 114.

[0316] In the illustrated embodiment, the ventilation system 110 is configured to deliver exhaust gas to the intake system 115 for supply to one or more cylinders 112 via the outlet portion 126. Therefore, the ventilation system 110 can be considered a closed-loop system. In the illustrated embodiment, exhaust gas is delivered from the crankcase 104 to the intake system 115 via the outlet portion 126.

[0317] In an alternative embodiment (not shown), the ventilation system 110 may not be configured to deliver exhaust gas to the intake system 115. In such an embodiment, the ventilation system 110 may be configured to discharge exhaust gas to the atmosphere (e.g., downstream of pump 114) and may be considered an open-loop system.

[0318] In an alternative embodiment (not shown), the ventilation system 110 is configured to draw any suitable gas (e.g., exhaust gas from combustion in one or more cylinders 112) into the ventilation path 116.

[0319] The intake passage 140 in the cylinder head 106 is separated from the ventilation path 116 in the cylinder head 106 and sealed to each other.

[0320] The intake system 115 includes a compressor 142 along an intake passage 140. A first position 140a is located upstream of the compressor 142. A second position 140b is located upstream of the compressor 142. The compressor 142 may be a turbocharger, a supercharger, or any device suitable for compressing engine intake air.

[0321] Pump 114 is configured to generate a lower pressure in crankcase 104 than the pressure at inlet 144 of compressor 142, which can help reduce fuel consumption and emissions. In the illustrated embodiment, compressor 142 generates a pressure of -60 to 0 mbar relative to atmospheric pressure at inlet 144.

[0322] The outlet portion 126 terminates above the footprint of the cylinder bank 108. In the illustrated embodiment, the outlet portion 126 terminates at a second position 140b of the intake passage 140. In this embodiment, the second position 140b is positioned above the rocker arm cover 107. Advantageously, terminating the outlet portion 126 above the footprint of the cylinder bank 108 helps ensure, during use, that at least a section of the outlet portion 126 is heated by combustion within one or more cylinders 112, thereby helping to prevent exhaust gases from freezing in the outlet portion 126.

[0323] Further references will be made below. Figures 4 to 16 Describe the ventilation path 116 in more detail.

[0324] like Figure 1 , Figure 4 and Figure 5 As shown, the inflow portion 125 of the ventilation path 116 includes a first segment 125a extending between the first location 140a and the inflow duct 302 of the routing unit 300. In the illustrated embodiment, the first segment 125a is a duct outside the engine structure 102, but in an alternative embodiment it may be at least partially located inside the engine structure 102.

[0325] like Figure 6 and Figure 8 As shown, the inflow portion 125 of the ventilation path 116 (in) Figures 6 to 10 (The arrow formed by two dashed lines indicates the direction of flow) from the inlet 308 to the outlet 310 of the inflow conduit 302 through the routing unit 300. The inflow conduit 302 is separate from the outflow conduit 304, which will be discussed more in the following text.

[0326] Further reference Figure 9 It shows along Figure 1 The view taken at section X4-X4 shows that the inflow portion 125 of the ventilation path 116 enters the first portion 109a of the gearbox 109 via an inflow orifice 312. The inflow orifice 312 is downstream of the inflow conduit 302. In the illustrated embodiment, the routing unit 300 is mounted to the gearbox 109 adjacent to the inflow orifice 312. Specifically, the routing unit 300 is mounted to the gearbox 109 to cover the orifice 312. In the illustrated embodiment, the outlet 310 of the inflow conduit 302 is adjacent to the orifice 312, such that the inflow conduit 302 and the first portion 109a of the gearbox 109 are aligned.

[0327] like Figure 8As shown, the housing 306 of the routing unit 300 includes a collar 314 defining an outlet 310. The collar 314 is received in and engages the inlet orifice 312. A seal 316 (which is an O-ring in the illustrated embodiment) is secured to the collar 314 and engages the periphery of the orifice 312 to seal the ventilation path 116 between the inlet conduit 302 and the gearbox 109.

[0328] In the illustrated embodiment, the inlet orifice 312 is located in the forward-facing wall 318 of the gearbox 109. In embodiments where the engine 100 is derived from a liquid-fuel engine, the orifice is typically located at this position to carry the drive shaft from the gearbox 109 to the fuel injection pump, thus allowing the orifice to be reused without reconfiguring the engine.

[0329] In the illustrated embodiment, the inlet orifice 312 is located above the cam gear 339a mounted to the camshaft 202. This position minimizes the amount of lubricating oil splashed toward the orifice 312 and thus toward the routing unit 300, which could at least partially block the inlet conduit 302.

[0330] In an alternative embodiment (not shown), the inlet orifice 312 may be located in any suitable part of the engine structure 102 (such as the crankcase 104).

[0331] refer to Figure 10 It shows along Figure 1 The view taken by section X1-X1 shows that the inflow portion 125 extends from the first portion 109a of the gearbox 109 to the crankcase 104 via one or more (e.g., multiple) crankcase inlets 127 in the wall separating the gearbox 109 and the crankcase 104. One or more crankcase inlets 127 are located at or toward the first axial end A1 of the engine structure 102 relative to or toward the crankshaft axis A.

[0332] In the illustrated embodiment, a portion of the outflow portion 126 of the ventilation path 116 is arranged in the engine structure 102. The outflow portion 126 passes through one or more of the cylinder bank 108, the cylinder head 106, the rocker arm cover 107, and the second portion 109b of the gearbox 109, which is separate from the first portion 109a.

[0333] As outlined below, the outflow portion 126 continuously passes through at least the cylinder bank 108, the cylinder head 106, and the rocker arm cover 107.

[0334] refer to Figure 11 It shows along Figure 1 The view taken by section X2-X2, the outflow portion 126 of ventilation path 116 (in Figures 11 to 13 and Figure 16(Indicated by the arrow formed by two solid lines) includes one or more airflow passages 120 in the engine structure 102 for conveying exhaust gases from the crankcase 104 to the rocker cover 107. In the illustrated embodiment, the outflow portion 126 includes a plurality of airflow passages 120 distributed across and along the crankcase 104. "Distributed across and along the crankcase" means that the positions of at least two inlets of the airflow passages 120 in the crankcase 104 are longitudinally offset and at least two inlets are laterally offset.

[0335] In the illustrated embodiment, the airflow passage 120 includes a plurality of longitudinally spaced pushrod passages 131, each pushrod passage being arranged to receive at least one of the pushrods 206 of the valve mechanism 200. Each pushrod passage 131 extends through the cylinder bank 108 and the cylinder head 106 and is in fluid communication with the crankcase 104 and the rocker arm cover 107. Advantageously, the use of the pushrod passages 131 eliminates the need for a separate dedicated airflow passage for exhaust gases between the cylinder head 106 and the crankcase 104, instead utilizing a pre-existing passage within the engine structure 102.

[0336] In some embodiments, the airflow passage 120 may additionally or alternatively include one or more (e.g., multiple) drain passages for draining oil from the cylinder head 106 to the crankcase 104, the drain passages being at least laterally spaced. For example, the airflow passage 120 may include all drain passages in the cylinder head 106. During operation of the engine 100, lubricating oil injected onto components of the valve mechanism 200 housed in the rocker arm cover 107 (e.g., rocker arm 204) is delivered to the oil reservoir 105 via the drain passages. The drain passages can extend from the rocker arm cover 107 through the cylinder head 106, cylinder bank 108, and crankcase 104 to the oil reservoir 105. The airflow passage 120 may include drain passages downstream of the cylinder head 106 and upstream of the crankcase 104 for the cylinder bank 108. The drain passages may form a network of drain passages including one or more inlets in the cylinder head 106 and one or more outlets in the crankcase 104. The number of inlets in cylinder head 106 can be greater than, less than or equal to the number of outlets in crankcase 104.

[0337] refer to Figure 12 It shows along Figure 1The image shows a view of the rocker cover 107 taken at section X1-X1, omitting components of the valve mechanism 200. The airflow passage 120 terminates in the rocker cover 107. Exhaust gas in the outlet portion 126 then exits the rocker cover 107 via an outlet 320. Similar to the one or more crankcase inlets 127 discussed previously, the rocker cover outlet 320 is located at or toward the first axial end A1 of the engine structure 102. In an alternative embodiment (not shown), the rocker cover outlet 320 and one or more crankcase inlets 127 may be located at or toward different axial ends of the engine structure 102.

[0338] Because one or more crankcase inlets 127 and rocker cover outlets 320 are located on a common end of engine structure 102, the ventilation gas flow within engine structure 102 may primarily flow along the airflow passage 120 closest to the first axial end A1, resulting in relatively less ventilation of crankcase 104 towards the relative second axial end A2 of engine structure 102. This can cause leak gas to stagnate in some areas of engine structure 102. Such stagnation of leak gas may cause the leak gas concentration in these areas to exceed the lower flammability limit of the gaseous fuel, thereby increasing the risk of leak gas ignition.

[0339] As described below, to mitigate this problem, the outflow portion 126 is configured to facilitate the flow of ventilation gas relative to the crankshaft axis A in the axial direction of the engine structure 102, thereby suppressing leakage stagnation in the engine structure 102. In the illustrated embodiment, the outflow portion 126 is configured to facilitate the flow of ventilation gas toward the second axial end A2 of the engine structure 102.

[0340] In the illustrated embodiment, the rocker cover 107 is configured to facilitate the flow of ventilation gas along the axial direction of the engine structure 102. In other words, the rocker cover 107 is configured to increase the flow of ventilation gas toward the second axial end A2 of the engine structure 102, and thus increase the flow of exhaust gas along the outflow portion 126 from the second axial end A2 of the crankcase 104 to the rocker cover 107. Advantageously, this guidance of the ventilation gas can help improve ventilation of leaks along the axial direction of the crankcase 104 and prevent stagnant areas in the engine structure 102 where the leak concentration is high and may exceed the lower flammability limit.

[0341] The rocker arm cover 107 includes a cavity 322 and a channel 324. The cavity 322 receives the rocker arm 204. The channel 324 is in fluid communication with the cavity 322 and terminates at a rocker arm cover outlet 320. An outflow portion 126 sequentially passes through the cavity 322, the channel 324, and then through the rocker arm cover outlet 320. In the illustrated embodiment, the channel 324 is configured to increase the flow of ventilation gas toward the second axial end A2 of the crankcase 104.

[0342] In the illustrated embodiment, channel 324 extends generally parallel to crankshaft axis A. This helps to increase the flow of exhaust gases from the second axial end A2 of crankcase 104 to rocker cap 107.

[0343] Figure 13 It is along Figure 1 The view of the rocker cover 107 taken at section X5-X5, in which the components of the air valve mechanism 200 are omitted. Figure 14 It is along Figure 13 The view of rocker cover 107 taken by section X9-X9. Figure 13 It also shows in Figure 12 The cross section X1-X1 seen in the image is provided for reference.

[0344] Further reference Figure 13 and Figure 14 The channel 324 is adjacent to the inner top side 330a of the rocker arm cover 107. In the illustrated embodiment, the rocker arm cover 107 includes a body 330 and a member 332, which, in the illustrated embodiment, is in the form of a plate and is mounted to the inner top side 330a of the body 330. The channel 324 is formed between the inner top side 330a of the body 330 and the member 332. The member 332 is... Figure 13 The main body 330 is generally indicated by shading. The main body 330 can be formed as a single integral material part (e.g., via casting or pressing processes).

[0345] The channel 324 includes a downstream portion 324a at or towards the first axial end A1, and an upstream portion 324b closer to the second axial end A2 relative to the downstream portion 324a. The upstream portion 324b of the channel 324 is more open toward the cavity 322 than the downstream portion 324a. Thus, since the pump 114 is downstream of the channel 324, the suction force from the cavity 322 to the channel 324 is higher closer to the second axial end A2, which increases the flow of exhaust gas along the outflow portion 126 from the second axial end A2 of the crankcase 104 to the rocker arm cover 107. "More open toward the cavity 322" means that the total area of ​​the flow path of exhaust gas from the cavity 322 to the upstream portion 324b of the channel 324 is larger than that of the downstream portion 324a.

[0346] The upstream portion 324b includes a plurality of upstream openings 326, each providing a pathway for exhaust gas from the cavity 322 to the channel 324. The upstream openings 326 include a first upstream opening 326a formed between the member 332 and the inner top side 330a. The first upstream opening 326a is closest to the second axial end A2 of the rocker cap 107 and has the largest area relative to the remaining openings 326, which helps to increase the suction force of the exhaust gas toward the second axial end A2. The upstream openings 326 also include a plurality of axially extending second upstream openings 326b, each in the form of a gap between the first lateral end 332a of the member 332 and the inner top side 330a. The upstream openings 326 also include a plurality of third upstream openings 326c, each in the form of a gap between a portion of the member 332 and the inner top side 330a, surrounding a countersunk bore 328 for receiving a portion of a spark plug (not shown). In an alternative embodiment (not shown), the upstream portion 324b may include one or more upstream openings 326 having any suitable configuration.

[0347] In the illustrated embodiment, the downstream portion 324a includes a plurality of downstream openings 340, each of which comprises a plurality of axially extending first downstream openings 340a, each first downstream opening being a gap between a first lateral end of the member 332 and an inner top side 330a. The downstream openings 340 also include a plurality of second downstream openings 340b, each second downstream opening being a gap between the member 332 and a portion of the inner top side 330a, surrounding a countersunk hole 328. Figure 14 As shown, the area of ​​the second upstream opening 326b is larger than the area of ​​the first downstream opening 340a. Furthermore, the area of ​​the third upstream opening 326c is larger than the area of ​​the second downstream opening 340b. Providing one or more openings to the downstream portion 324a helps to suppress the formation of stagnant regions in the exhaust gas toward the first axial end A1. In an alternative embodiment (not shown), the downstream portion 324b may not include the downstream opening 340, or may include one or more downstream openings 340 with any suitable configuration.

[0348] In the illustrated embodiment, there is no opening between the second lateral end 332b of the member 332, which is opposite to the first lateral end 332a, and the inner top side 330a, but such an opening may exist in an alternative embodiment.

[0349] In an alternative embodiment (not shown), in addition to the orifice for receiving the spark plug, component 332 may also include one or more orifices that provide passage between cavity 322 and channel 324.

[0350] In some embodiments, the upstream portion 324b extends 5% to 50% of the width of the cavity 322 between the first axial end A1 and the second axial end A2; optionally, it extends 10% to 50% of the width of the cavity; optionally, it extends 20% to 50% of the width of the cavity.

[0351] In an alternative embodiment (not shown), the rocker cover 107 can have any suitable configuration to increase the flow of ventilation gas toward the second axial end A2 of the engine structure 102. For example, the rocker cover 107 may include one or more suitably arranged baffles.

[0352] Figures 25 to 27 An alternative embodiment of the rocker cover is shown, denoted by reference numeral 107'. Features common to the rocker cover 107 of the previous embodiment share common reference numerals, and for the sake of brevity, descriptions of these features will not be repeated. The rocker cover 107' may share any features described with respect to the rocker cover 107, and vice versa.

[0353] Figure 25 It shows something similar to Figure 12 The image shows a cross-sectional view of the rocker cover 107'. Compared to the aforementioned embodiment, the rocker cover 107' does not include the channel 324 or the component 332.

[0354] The rocker arm cover 107' includes an oil-fill conduit 600 for receiving oil or another lubricant to replenish the engine 100. The oil-fill conduit 600 includes an oil inlet 602 that is closed via a removable closure 604, such as an oil filler cap. When the closure 604 is removed, oil poured into the oil inlet 602 flows through a cavity 322 in the rocker arm cover 107 and passages in the cylinder head 106, cylinder bank 108, and crankcase 104 to an oil reservoir 105. The rocker arm cover 107 of the aforementioned embodiment includes a similar oil-fill conduit 600. In alternative embodiments (not shown), different parts of the engine structure 102 may include the oil-fill conduit 600.

[0355] In the illustrated embodiment, the oil filling conduit 600 is located at or toward the second axial end A2 of the engine structure 102.

[0356] like Figure 25 As shown, the oil filling conduit 600 includes a rocker cap outlet, which is indicated by reference numeral 320' in this embodiment. Thus, the rocker cap outlet 320' is located at or toward the second axial end A2 of the engine structure 102, which facilitates the flow of ventilation gas from the first axial end A1 to the second axial end A2 along the axial range of the engine structure 102.

[0357] refer to Figure 26 It shows along Figure 25 The view taken at section X12-X12 shows that the oil-filled conduit 600 includes a chamber 620 protruding from the body 330 of the rocker cap 107'. An outlet portion 126 of the ventilation path extends from a cavity 332 in the body 330 to the chamber 620. The chamber 620 includes a rocker cap outlet 320'. In an alternative embodiment (not shown), another portion of the engine structure 102, besides the oil-filled conduit 600, may include the chamber 600 and the outlet.

[0358] In the illustrated embodiment, chamber 620 has a larger flow cross-sectional area (i.e., perpendicular to the average flow direction) relative to rocker cap outlet 320'. For example, the flow cross-sectional area of ​​chamber 620 upstream of and / or adjacent to rocker cap outlet 320' can be larger than that of rocker cap outlet 320'. This helps to reduce the flow velocity of the exhaust gas through chamber 620. The reduced exhaust gas velocity promotes the deposition of oil and other liquids entrained by the exhaust gas, and thus reduces the oil concentration in the exhaust gas downstream of rocker cap outlet 320'.

[0359] In the illustrated embodiment, during normal operation of the engine 100, the chamber 620 is configured such that the exhaust gas travels substantially upwards before passing through the rocker cover outlet 320'. For example, the chamber 620 may protrude substantially upwards from the body 330 of the rocker cover 107'. This forces the exhaust gas to flow against gravity, which helps to promote the deposition of oil and other liquids entrained by the exhaust gas.

[0360] In the illustrated embodiment, chamber 620 is defined by an outer peripheral wall 624. The rocker cap outlet 320' includes an outlet conduit 606 extending through the outer peripheral wall 624. The outlet conduit 606 has a first open end 606a and a second open end 606b. The first open end 606a and the second open end 606b are in fluid communication with each other. The first open end 606a is within chamber 620 and spaced apart from the outer peripheral wall 624. It has been found that positioning the first open end 606a within chamber 620 and spaced apart from the outer peripheral wall 624 helps to facilitate the deposition of oil and other liquids entrained by the exhaust gas. The second open end 606b is outside chamber 620 and spaced apart from the outer peripheral wall 624.

[0361] The outlet conduit 606 has a longitudinal axis 608. The length of the outlet conduit 606 along the longitudinal axis 608 between the first opening end 606a and the outer peripheral wall 624 can be greater than 20% of the corresponding width of the chamber 620, for example, greater than 30% of the width, for example, greater than 40% of the width, for example, greater than 50% of the width.

[0362] In the illustrated embodiment, the oil inlet 602 of the oil-filled conduit 600 is located above the rocker cap outlet 320'. The rocker cap outlet 320' is configured to prevent oil received in the oil inlet 602 from passing through the rocker cap outlet 320'. In the illustrated embodiment, the first open end 606a of the outlet conduit 606 is oriented away from the oil inlet 602, for example, generally downward. This prevents oil received in the oil inlet 602 from traveling directly into the outlet conduit 606 via the first open end 606a.

[0363] In the illustrated embodiment, in the normal operating orientation of the engine 100, the first opening end 606a is located below the second opening end of the outlet conduit 606, thereby preventing the oil that has entered the first end 606a of the outlet conduit 606 from flowing to the second opening end 606b under the action of gravity.

[0364] In the illustrated embodiment, in the normal operating orientation of the engine 100, the longitudinal axis 608 of the outlet conduit 606 is inclined downward in the direction from the second opening end 606b to the first opening end 606a. This helps to ensure that the oil in the outlet conduit 606 leaves the outlet conduit 606 under the influence of gravity via its first opening end 606a, allowing the oil to return to the engine structure 102.

[0365] In an alternative embodiment (not shown), the rocker cover outlet 320' can have any suitable configuration. Further reference Figure 27 In this embodiment, the segment 126a of the outflow portion 126 (in) Figure 27 (Indicated by dashed lines) The design is modified relative to the previous embodiment to extend from the rocker cap outlet 320' near the second axial end A2 to the routing unit 300 near the first axial end A1. The oil filling conduit 600 is located on the top side of the rocker cap 107' and protrudes from the top outer surface 601 of the rocker cap 107' (e.g., upward). This helps to reduce the length of the outflow portion 126 in the segment 126a between the rocker cap outlet 320' and the routing unit 300, simplifies the assembly and inspection of the outflow portion 126, and helps to ensure that the exhaust gas travels generally upward before passing through the rocker cap outlet 320', as described above.

[0366] refer to Figure 1 and Figures 3-6 The outflow portion 126 includes a segment 126a extending between the rocker cover outlet 320 and the outflow conduit 304 of the routing unit 300. In the illustrated embodiment, the segment 126a is an external pipe 126a located outside the engine structure 102, and will be discussed in more detail below.

[0367] like Figure 6 and Figure 7As shown, the outflow portion 126 of the ventilation path 116 extends from the inlet 350 through the outflow conduit 304 to a pair of outlets 352 of the outflow conduit 304. The outflow conduit 304 is separate from the inflow conduit 302, as described above. In an alternative embodiment (not shown), the outflow conduit 304 may include only one outlet, or may include more than two outlets 352.

[0368] The outflow conduit 304 is configured to reduce the oil concentration in the exhaust gas at the outlet 352 relative to the inlet 350, and thus, as previously discussed, functions as an oil separator.

[0369] In the illustrated embodiment, the outflow conduit 304 is configured such that the exhaust gas traveling from the inlet 350 to the outlet 352 changes its flow direction multiple times, and the flow cross-section and thus the flow velocity changes. Advantageously, this results in the deposition of oil and other liquids (e.g., water as a byproduct of hydrogen combustion) entrained in the exhaust gas within the outflow conduit 304.

[0370] The outflow conduit 304 includes a wall 354 arranged to deflect the exhaust gas traveling from inlet 350 to outlet 352. In the illustrated embodiment, wall 354 faces inlet 350 to force a first change in flow direction. Wall 354 is arranged substantially perpendicular to the flow direction of the exhaust gas immediately upstream of wall 354, which helps to increase the deposition of oil and other liquids. In alternative embodiments (not shown), wall 354 can have any suitable configuration. For example, outflow conduit 304 may additionally or alternatively include one or more walls in the form of baffles within outflow conduit 304.

[0371] The wall 354 includes a textured (i.e., non-smooth) surface 354a. This increases the surface area of ​​the wall 354 in contact with the exhaust gas, which helps to increase the deposition of oil and other liquids. In the illustrated embodiment, a portion of the textured surface 354a is arranged opposite the inlet 350 such that the exhaust gas contacts the textured surface 354a after flowing through the inlet 350 into the outlet conduit 304. In an alternative embodiment (not shown), one or more other portions of the outlet conduit 304 may alternatively or additionally include textured surfaces arranged for contact with the exhaust gas.

[0372] In the illustrated embodiment, the outflow conduit 304 includes a dog-leg portion 356, which includes an outlet 352. The dog-leg portion 356 forces a second change in the flow direction of the exhaust gas before it reaches the outlet 352. In an alternative embodiment (not shown), the exhaust gas traveling from the inlet 350 to the outlet 352 may change its flow direction once or more (e.g., twice or more). For example, the outflow conduit 304 may force the exhaust gas to travel along a tortuous path between the inlet 350 and the outlet 352.

[0373] The outflow conduit 304 is configured to reduce the velocity of the exhaust gas traveling from inlet 350 to outlet 352, which facilitates the deposition of oil and other liquids. In the illustrated embodiment, the outflow conduit 304 includes a first portion 304a upstream of a second portion 304b. The cross-sectional area of ​​the second portion 304b perpendicular to the flow direction of the exhaust gas is larger than that of the first portion 304a. Thus, the velocity of the exhaust gas in the second portion 304b is less than the velocity of the exhaust gas in the first portion 304a. In an alternative embodiment (not shown), the outflow conduit 304 may have any suitable configuration for reducing the velocity of the exhaust gas traveling from inlet 350 to outlet 352 (e.g., the outflow conduit 304 may include one or more baffles).

[0374] like Figure 6 As shown, the outflow conduit 304 includes a discharge outlet 358 for discharging oil and other liquids from the outflow conduit 304.

[0375] As will be outlined below, the outflow portion 126 of the ventilation path 116 delivers exhaust gas from the outflow conduit 304 sequentially to the pump 114, the oil separator 130, and then to the outflow orifice 360 ​​in the gearbox 109.

[0376] like Figure 4 and Figure 5 As shown, each of the two outlets 352 of the outflow conduit 304 is fluidly connected to a corresponding inlet 114i of the pump 114 via a connection passage 362 of the outflow portion 126. In the illustrated embodiment, the pump 114 is a side-channel pump (also referred to as a side-channel blower) with two inlets 114i. The pump 114 includes an impeller (not shown) rotatable within a housing about a rotation axis to move fluid at the two inlets 114i to an outlet (not shown). The two inlets 114i are arranged on opposite sides of the plane of rotation of the impeller.

[0377] In the illustrated embodiment, pump 114 is arranged such that the axis of rotation of the impeller is substantially vertical in the normal operating orientation of engine 100. For example, the axis of rotation of the impeller may be substantially parallel to the axis of cylinder 112. This arrangement of the impeller has been found to facilitate the discharge of oil and other liquids deposited from exhaust gases within pump 114 from at least the lowermost inlet 114i. Each of the two connecting passages 362 slopes downward from the corresponding pump inlet 114i toward the corresponding outlet 352 of the outlet conduit 304. Advantageously, this facilitates the discharge of oil and other liquids from pump 114 to outlet conduit 304, from which the oil and other liquids may be discharged via discharge outlet 358. In an alternative embodiment (not shown), pump 114 may include only one inlet 114i and / or more than one outlet 114o (e.g., two outlets 114o).

[0378] refer to Figure 15 The outlet of pump 114 is fluidly connected to the inlet 130i of oil separator 130 via a connection passage 364 of the outflow portion 126. As described above, in this embodiment, oil separator 130 is a cyclone oil separator. The cyclone oil separator 130 causes exhaust gas to flow through it to form a vortex. The exhaust gas enters separator 130 through inlet 130i and forms a vortex. The exhaust gas then leaves oil separator 130 via gas outlet 130o. As will be discussed in more detail below, the separated oil leaves separator 130 via oil outlet 412.

[0379] refer to Figure 5 , Figure 9 and Figure 15 The gas outlet 130o of separator 130 is fluidly connected to the outlet orifice 360 ​​in gearbox 109 via a connection passage 368 of outlet portion 126. Outlet orifice 360 ​​leads to a second portion 109b of gearbox 109, such that outlet portion 126 passes through the second portion 109b. The second portion 109b is separated from the first portion 109a of gearbox 109, such that ventilation gas traveling through the first portion 109a cannot mix with exhaust gas traveling through the second portion 109b.

[0380] In an alternative embodiment (not shown), the outlet orifice 360 ​​may be located in any suitable part of the engine structure 102 (e.g., cylinder bank 108 or cylinder head 106).

[0381] refer to Figure 1 , Figure 9 and Figure 16 Exhaust gas exits the second portion 109b of gearbox 109 via passage 380 in engine structure 102. Outflow portion 126 continuously passes from the second portion 109b of gearbox 109 within engine structure 102 through cylinder bank 108, cylinder head 108, and rocker arm cover 107, reaching outlet 370 in rocker arm cover 107. This section of outflow portion 126 passing through rocker arm cover 107 is separated from and sealed to cavity 322 and passage 324. Thus, exhaust gas passing upstream of oil separator 130 through rocker arm cover 107 cannot mix with exhaust gas passing downstream of oil separator 130 through rocker arm cover 107. Outlet 370 is fluidly connected to the second position 140b of intake passage 140 via connection passage of outflow portion 126 (see...). Figure 3 ).

[0382] from Figure 4 and Figure 9It is understood that, in the illustrated embodiment, the routing unit 300 is mounted to the gearbox 109 adjacent to the outlet port 360, which helps to improve the enclosure of the ventilation system 110. In an alternative embodiment (not shown), the routing unit 300 may have any suitable mounting location on the engine structure 102.

[0383] like Figures 6 to 8 As shown, the inflow conduit 302 intersects with and extends over the outflow conduit 304. This helps to improve the encapsulation of the ventilation system 110 and simplifies the assembly of the ventilation system 110.

[0384] In the illustrated embodiment, the inflow and outflow conduits 302, 304 are integrally formed (i.e., they share at least one common wall). This helps reduce the size of the routing unit 300, thereby contributing to improved encapsulation of the ventilation system 110. Furthermore, the integral formation of the inflow conduit 302 and outflow conduit 304 with the housing 306 further contributes to a reduction in the size of the routing unit 300. The inflow conduit 302 and outflow conduit 304, as well as the housing 306, are formed of a suitable plastic that does not react with water and oil, but in alternative embodiments they may be formed of any suitable material (e.g., a metal such as aluminum or stainless steel).

[0385] In the illustrated embodiment, the routing unit 300 is formed of a plurality of connected components, wherein each component is formed as a single monolithic material part (e.g., via casting, molding, or additive manufacturing processes). In an alternative embodiment, the routing unit 300 may be formed as a single monolithic material part, for example, via an additive manufacturing process.

[0386] The ventilation system 110 is configured such that the gas pressure in the crankcase 104 (and therefore in the oil reservoir 105) is higher than the gas pressure in the oil pre-separator 304 (i.e., in the outflow duct 304 in the illustrated embodiment). This is because the pump 114 is located downstream of the oil pre-separator 304, and therefore the pressure in the crankcase 104 will be relatively higher due to pressure loss. Given this pressure difference, there is a potential problem that when the engine 100 is running, the oil and other fluids collected by the oil pre-separator 304 cannot be discharged into the oil reservoir 105.

[0387] Existing technical solutions to this problem involve using a valve to control the flow of oil from the oil separator to the reservoir. This valve opens only when the pressure in the oil separator and reservoir is equalized (e.g., when the engine is not running). However, the use of a valve increases the number of moving parts in the engine, as well as the associated maintenance requirements. Furthermore, some engines (such as those used in generator sets) need to run for extended periods without stopping, thus requiring the storage of large quantities of oil before it can be returned to the reservoir used for such engines.

[0388] refer to Figure 4 , Figure 5 and Figure 17 To mitigate the aforementioned problems, engine 100 includes a first discharge conduit 400 arranged to deliver oil removed from the exhaust gases by oil pre-separator 304 to oil reservoir 105. As outlined below, the first discharge conduit 400 is configured to maintain an oil head for applying hydrostatic pressure to the oil in oil reservoir 105, thereby inhibiting the delivery of gases from crankcase 104 to oil pre-separator 304 via the first discharge conduit 400 during operation. Thus, as long as the oil head is maintained, oil removed from the exhaust gases by oil pre-separator 304 can be consistently discharged to oil reservoir 105 despite the pressure difference between crankcase 104 and oil pre-separator 304. Therefore, it is not necessary to change the operation of ventilation system 110 (e.g., balancing the pressure in crankcase 104 and oil pre-separator 304) to allow the removed oil to be discharged to oil reservoir 105.

[0389] In the illustrated embodiment, the first exhaust duct 400 is arranged outside the engine structure 102, which helps to simplify the assembly and maintenance of the engine 102.

[0390] In an alternative embodiment (not shown), at least a portion of the first exhaust duct 400 may be arranged within the engine structure 102. Arranging at least a portion of the first exhaust duct 400 within the engine structure 102 reduces the requirements for customizing components of the engine structure 102 (e.g., oil tanks) for an engine with a CCV system as described herein.

[0391] like Figure 17 As shown, a first end 400a of the first discharge conduit 400 is fluidly connected to the discharge outlet 358 of the oil pre-separator 304. A second end 400b of the first discharge conduit 400 is fluidly connected to the oil reservoir 105. In the illustrated embodiment, the first discharge conduit 400 is configured to allow oil to flow from the first end 400a to the second end 400b without obstruction by moving parts such as valves. This reduces the maintenance requirements of the engine 100.

[0392] Figure 18A schematic diagram of the crankcase 104, oil reservoir 105, and first discharge duct 400 is shown. In the following text, "p1" should represent the gas pressure in the crankcase 104, "p2" should represent the gas pressure in the oil pre-separator 304, "h1" should represent the oil head in the oil reservoir 105 relative to the horizontal reference plane 402, and "h2" should represent the oil head in the first discharge duct 400 relative to the reference plane 402. As described above, when the engine 100 is running, the gas pressure p1 in the crankcase 104 is greater than the gas pressure p2 in the oil pre-separator (i.e., p1>p2). It should be understood that in order to balance the hydrostatic pressure of the oil in the oil reservoir 105 and the first discharge duct 400, the following equation must be satisfied: , in It is acceleration caused by gravity, and It is the density of the oil.

[0393] Therefore, in order to prevent gas in crankcase 104 from being transported to oil pre-separator 304 via first discharge conduit 400, first discharge conduit 400 must maintain a head (liquid column height): .

[0394] In other words, the first discharge conduit 400 must maintain an additional oil head relative to the oil reservoir 105, which corresponds to: , in .

[0395] In the illustrated embodiment, during operation of the engine 100, the difference between the gas pressure p1 in the crankcase 104 and the gas pressure p2 in the oil pre-separator 304 (i.e., p1-p2) is approximately 0.6 Pa, which corresponds to an additional oil head of approximately 80 mm in the first discharge duct 400 relative to the oil reservoir 105. ).

[0396] To ensure that sufficient oil head h2 can be retained in the first discharge conduit 400, the first end 400a of the first discharge conduit 400 is connected to the oil pre-separator 304, located at or above the level of the crankcase 104. In the illustrated embodiment, the first end 400a of the first discharge conduit 400 is located at the level of the cylinder bank 108, but in alternative embodiments it may be higher (e.g., at the level of the cylinder head 106).

[0397] In the illustrated embodiment, the first discharge conduit 400 is arranged to deliver oil adjacent to the bottom 105a of the oil reservoir 105, such as... Figure 17As shown. This helps mitigate the risk that the oil level in the reservoir 105 may drop below the second end 400b of the first discharge duct 400, which could cause gas in the crankcase 104 to bypass the oil and travel along the first discharge duct 400 to the oil pre-separator 304.

[0398] In the illustrated embodiment, the gas pressure in the crankcase 104 upstream of pump 114 is lower than the gas pressure in the oil separator 130 downstream of pump 114. This pressure difference facilitates the discharge of oil from the oil separator 130 to the oil reservoir 105 under gravity. As described below, the engine 100 includes a second discharge conduit separate from the first discharge conduit 400, which is arranged to deliver oil removed from the exhaust gases by the oil separator 130 to an inlet portion 416 of the engine structure 102, which leads to the oil reservoir 105.

[0399] refer to Figure 19 As shown in Figure 20, the oil separator 130 includes: a separator section 130a configured to separate oil from exhaust gas; and an outlet section 130b installed to the separator section 130a. The separator section 130a includes an oil separator inlet 130i and a gas outlet 130o. The outlet section 130b includes an oil outlet 412 in fluid communication with the separator section 130a for discharging the separated oil from the oil separator 130.

[0400] In the illustrated embodiment, separator section 130a creates a vortex in the exhaust gas flow entering it via oil separator inlet 130i to separate oil from the exhaust gas via the centrifugal effect of the vortex. Separator section 130a includes an internal chamber 413 having a truncated conical portion 415 and a cylindrical portion 417. The cylindrical portion 417 is adjacent to the truncated conical portion 415. Exhaust gas enters chamber 413 from oil separator inlet 130i via cylindrical portion 417. Gas exits chamber 413 via gas outlet 130o via cylindrical portion 417.

[0401] The outlet portion 130b is substantially disposed below the separator portion 130a. In the illustrated embodiment, the outlet portion 130b is mounted to the apex 415a of the truncated conical portion 415 via a push-fit mounting device. In an alternative embodiment (not shown), the outlet portion 130b may be mounted to the separator portion 130a by any suitable means (e.g., via adhesive and / or one or more fasteners).

[0402] During operation, the separated oil flows down the wall 414 of chamber 413 to the apex 415a, and then flows to the outlet portion 130b, as shown. Figure 20aAs indicated by the dashed arrow in the figure. In an alternative embodiment (not shown), the separator section 130a may have any suitable configuration for separating oil from the exhaust gas (e.g., the oil separator may be an active centrifugal oil separator).

[0403] The crankcase 104 includes an inlet portion 416, which includes an oil inlet 420. The oil inlet 420 is in fluid communication with an oil reservoir 105. Oil entering the oil inlet 420 travels within the engine structure 102 to the oil reservoir 105 under the influence of gravity.

[0404] Outlet portion 130b is mounted to inlet portion 416, allowing oil exiting oil outlet 412 to enter oil inlet 420, and thus separator portion 130a is mounted to engine structure 102. Advantageously, mounting separator portion 130a to engine structure 102 by mounting outlet portion 130b to inlet portion 416 helps improve ventilation system encapsulation and simplify engine assembly, as no additional lines are required to deliver discharged oil from separator portion 130a to engine structure 102, and no additional lower mounting bracket is needed for oil separator 130. In an alternative embodiment (not shown), any suitable portion of engine structure 102 may include inlet portion 416 (e.g., cylinder bank 108 or cylinder head 106).

[0405] like Figure 4 and Figure 15 As shown, in the illustrated embodiment, the separator portion 130a is also mounted to the cylinder bank 108 of the engine structure 102 via a fastener 423 that passes through a mounting bracket 425 of the oil separator 130 and is received in an orifice in the cylinder bank 108. The mounting bracket 425 extends from the separator portion 130b. This additional mounting connection between the oil separator 130 and the engine structure 102 provides a stronger and more rigid connection between the two components. In an alternative embodiment (not shown), the separator portion 130a may be mounted to the engine structure 102 simply by mounting the outlet portion 130b to the inlet portion 416.

[0406] In the illustrated embodiment, outlet portion 130b includes a male portion 422, and inlet portion 416 includes a female portion 424. The male portion 422 includes an oil outlet 412. The female portion 424 includes an oil inlet 420. The male portion 422 is received within the female portion 424. Advantageously, the male portion 422 and the female portion 424 provide positioning features to facilitate the simplification of engine 100 assembly. In an alternative embodiment (not shown), outlet portion 130b may include the female portion 424, and inlet portion 416 may include the male portion 422. Alternatively, outlet portion 130b and inlet portion 416 may not include such male and female portions.

[0407] In the illustrated embodiment, the male portion 422 includes a male thread extending around the outlet 412 on its surface 426. The female portion 424 includes a corresponding female thread. The outlet portion 130b is mounted to the inlet portion 416 via the engagement of the male and female threads.

[0408] The male portion 422 is rotatable relative to the separator portion about the threaded axis 428 of the male portion 422 to engage the male and female threads. In the illustrated embodiment, the outlet portion 130b includes a housing 430 and a barrel 432. The housing 430 is mounted to the separator portion 130a. The barrel 432 extends through a hole in the housing 430 and is rotatable relative to the housing 430 about the threaded axis 428. The barrel 432 includes the male portion 422. In the illustrated embodiment, the barrel 432 includes a recess 434 that engages with a tool such as a screwdriver or an Allen wrench to rotate the male portion 422 about the threaded axis 428. The recess 434 is opposite the oil outlet 412.

[0409] The cylinder 432 includes an axial bore 435 substantially aligned with the threaded axis 428, and a plurality of radial bores 437 extending radially from the axial bore 435. The axial bore 435 and the radial bores 437 are arranged such that oil discharged from the separator section 130a travels along one radial bore 437, along the axial bore 435, and then exits through the oil outlet 412, regardless of how the cylinder 432 is oriented relative to the housing 430.

[0410] In alternative embodiments (not shown), the recess 434 may have any suitable location on the outlet portion 130b. For example, in some embodiments, the recess 434 may be rotated via an intervention mechanism (such as a gear mechanism) of the outlet portion 130b by means of rotation of the tool, causing the cylinder 432 to rotate.

[0411] In the illustrated embodiment, the oil separator 130 is mounted to the engine structure 102 such that the separator portion 130a is adjacent to the inlet portion 416. This helps to reduce the spatial footprint of the oil separator 130 and thus helps to improve the enclosure of the ventilation system 110. In alternative embodiments, the oil separator 130 can have any suitable mounting configuration.

[0412] like Figure 20a As shown, the separator section 130a is elongated and has a longitudinal axis 440. The longitudinal axis 440 is substantially perpendicular to the axis of the oil outlet 412, which, in the illustrated embodiment, is aligned with the screw axis 428.

[0413] Advantageously, this configuration helps to improve the encapsulation of the ventilation system 110.

[0414] In the illustrated embodiment, the maximum length of the outlet portion 130b is less than the maximum length of the separator portion 130a. Furthermore, the volume of the outlet portion 130b is less than the volume of the separator portion 130a. Advantageously, this helps to improve the encapsulation of the ventilation system 110.

[0415] The oil separator 130 includes a first sealing device located between the outlet portion 130b and the inlet portion 416. The first sealing device is configured to prevent oil leakage traveling from the oil outlet 412 toward the oil inlet 420. In the illustrated embodiment, the sealing device includes a first sealing member 442a in the form of an O-ring (in... Figure 20a (Indicated by a dashed circle), but any suitable sealing member can be used. The first sealing member 442a makes sealing contact with the surface 426 extending around the outlet 412 and the oil inlet 420. In an alternative embodiment (not shown), the engine 100 may include any suitable first sealing device. For example, the inlet portion 416 may additionally or alternatively include one or more sealing members.

[0416] The oil separator 130 includes a second sealing device located between the separator portion 130a and the outlet portion 130b, configured to prevent oil leakage therebetween. In the illustrated embodiment, the second sealing device includes a second sealing member 442b and a third sealing member 442c that make sealing contact with the opposing axial ends of the cylinder 432 and the housing 430. The second sealing device also includes a fourth sealing member 442d that makes sealing contact with the truncated conical portion 415 of the separator portion 130a and the housing 430.

[0417] Figure 20b An oil separator 130' according to an alternative embodiment is shown. Figure 19 and Figure 20a The common features of the oil separator 130 shown share common reference numerals, and for the sake of brevity, their descriptions will not be repeated.

[0418] Compared to the previous embodiments, Figure 20b The housing 430' of the outlet portion 130b' of the oil separator 130' shown, and the apex 415a of the truncated conical portion 415 (e.g., via casting or molding processes) are formed as a single integral piece of material. This eliminates the need for a fourth sealing member 442d. This configuration of the oil separator 130' simplifies the assembly of the engine 100. In an alternative embodiment (not shown), any suitable portion of the housing and separator portion can be formed as a single integral piece of material.

[0419] In the illustrated embodiment, the engine 100 is powered by hydrogen. Therefore, leakage includes gases formed by the combustion of hydrogen, which include water vapor. Water vapor in the exhaust gas is prone to freezing if subjected to sufficiently cold external temperatures. This freezing can cause blockage of ventilation paths and damage components of the ventilation system 110. A section of the outflow portion 126 within the engine structure 102 is heated by the heat released from the combustion of gaseous fuel in the cylinder 112, which inhibits the freezing of water vapor traveling along that section, even when the ambient temperature is below freezing. However, one or more sections of the outflow portion 126 (such as external duct 126a) are outside the engine structure 102, making water vapor in these sections more susceptible to freezing.

[0420] refer to Figure 21 and Figure 22 To suppress icing in the exposed section of the outflow portion 126, embodiments of the engine 100 include a heat transfer device 500 configured to transfer heat generated by combustion from the engine structure 102 to the external duct 126a to heat the exhaust gases transported therein. Advantageously, transferring the heat generated by combustion to the external duct 126a helps suppress the freezing of water vapor in the exhaust gases. Furthermore, using heat generated by combustion, rather than heat generated by electricity, to heat the external duct 126a eliminates the need for electrical heating of the external duct 126a, thus helping to reduce parasitic energy losses in the engine 100.

[0421] like Figure 21 and Figure 22 As shown, the heat transfer device 500 includes a heat transfer path 502 (in Figure 22 (represented by a dashed line) and a fluid pressure source 504, which in the illustrated embodiment is a pump. The fluid pressure source 504 is configured to deliver heat transfer fluid from engine structure 102 to portion 501 of external conduit 126a along heat transfer path 502. Figure 22 (represented by solid double lines) to transfer the heat generated by combustion to this part of the external conduit. The heat transfer path 502 may take a tortuous route that passes at least through the cylinder bank 108 to increase the heat transfer from the cylinder bank 108 to the heat transfer path 502.

[0422] In an alternative embodiment (not shown), the heat transfer device 500 can transfer the heat generated by combustion from the engine structure 102 to all external ducts 126a.

[0423] In the illustrated embodiment, the heat transfer device 500 includes a heat exchanger 506 (e.g., a radiator) in the heat transfer path 502. The heat transfer device 500 is also configured to transfer heat generated by combustion from the engine structure 102 via an engine fluid passage including a cylinder cooling jacket to the heat exchanger 506 to cool the engine structure 102, which is conventional for internal combustion engines. Advantageously, this configuration of the heat transfer device 500 eliminates the need for separate piping for the engine cooling system and for the heating system of the outflow portion 126. In an alternative embodiment (not shown), the heat transfer device 500 may be separate from the engine cooling system, and therefore the heat exchanger 506 may not be included.

[0424] In the illustrated embodiment, the heat transfer fluid comprises water and may also include an antifreeze additive. In an alternative embodiment (not shown), the heat transfer fluid may comprise any suitable liquid or gas. For example, the heat transfer fluid may be exhaust gas, i.e., combustion gas discharged from cylinder 112. In such an embodiment, the fluid pressure source 504 may be used to compress the exhaust gas by piston 113 in cylinder 112.

[0425] like Figure 22 As shown, the heat transfer path 502 is a closed path. Thus, the fluid pressure source 504 causes the heat transfer fluid to circulate around the heat transfer path 502.

[0426] The heat transfer path 502 exits the engine structure 102 via the first orifice 508 in the engine structure 102, passes through a portion 501 of the external conduit 126a, and then enters the engine structure 102 via the second orifice 510 in the engine structure 102.

[0427] like Figure 21 As shown, in the illustrated embodiment, a portion 501 of the external conduit 126a is adjacent to the cylinder head 106 and the rocker arm cover 107. A first orifice 508 and a second orifice 510 are located within the cylinder head 106. This helps to reduce the length of the conduit 512 between the first orifice 508 and the external conduit 126a, and the length of the conduit 514 between the second orifice 510 and the external conduit 126a. In an alternative embodiment (not shown), a portion 501 of the external conduit 126a may be adjacent to one or both of the cylinder head 106 and the cylinder bank 108. In such an embodiment, each of the first orifice 508 and the second orifice 510 may be located within either the cylinder head 106 or the cylinder bank 106.

[0428] Further reference Figure 23 It shows along Figure 21The view, taken at cross section X11-X11, shows that the heat transfer path 502 includes an annular conduit 518 substantially surrounding a portion 501 of the outer conduit 126a for transferring heat generated during combustion from a heat transfer fluid within the conduit 518 to the portion 501. Advantageously, this helps to maximize the outer surface area of ​​the portion 501 in contact with the heat transfer fluid, thereby more efficiently transferring heat generated during combustion from the engine structure 102 to the outer conduit 126a. In an alternative embodiment (not shown), the conduit 518 may not be annular, but may only partially surround a portion 501 of the outer conduit 126a.

[0429] Figure 24 A schematic representation of a heat transfer device 500' according to another embodiment is shown. Figures 21 to 23 The heat transfer devices 500 shown share common reference numerals and, for the sake of brevity, will not be described again.

[0430] refer to Figure 24 The heat transfer device 500' includes a passive heat transfer device 528, which is configured to transfer heat generated by combustion from the engine structure 102 to a portion 501 of the external duct 126a. A "passive heat transfer device" is defined as a heat transfer device that does not require an external power source to transfer heat from the engine structure 102 to the external duct 126a.

[0431] In an alternative embodiment (not shown), the passive heat transfer device 528 can transfer the heat generated by combustion to all external conduits 126a.

[0432] In the illustrated embodiment, the passive heat transfer device 528 includes a heat transfer member 530 connected to a portion 102a of the engine structure 102 and a portion 501 of the external conduit 126a. The heat transfer member 530 is configured to transfer heat generated by combustion from the portion 120a of the engine structure 102 to the portion 501 of the external conduit 126a.

[0433] In the illustrated embodiment, the heat transfer member 530 includes an annular portion 532 that substantially surrounds the portion 501 of the outer conduit 126a, similar to... Figure 23 The conduit 518 shown. This helps increase the contact surface area between the heat transfer member 530 and portion 501, so as to more effectively transfer the heat generated by combustion from the engine structure 102 to the external conduit 126a. In an alternative embodiment (not shown), the heat transfer member may only partially surround portion 501 of the external conduit 126a.

[0434] The heat transfer member 530 also includes a connector portion 534 that connects the annular portion 532 to the outer surface 102b of portion 102a of the engine structure 102. The connector portion 534 can have any suitable geometry. For example, in some embodiments, the connector portion 534 can be flat. In some embodiments, the connector portion 534 can be formed of two or more separate portions, each connected to both the engine structure 102 and portion 501.

[0435] The connector portion 534 and the annular portion 532 may be formed as a single integral material part (e.g., via a casting process), or may be formed as two parts fixed to each other (e.g., via welding or bonding processes and / or via one or more fasteners). The connector portion 534 may be fixed to the outer surface 102b of the engine structure 102 by any suitable means (e.g., via welding, bonding, and / or one or more fasteners). A layer of thermally conductive paste may be included between the outer surface 102b of the engine structure 102 and the connector portion 534, and / or between the connector portion 534 and the annular portion 532.

[0436] Part 102a of engine structure 102 may be formed of a first material, and heat transfer member 530 may be formed of a second material having a thermal conductivity greater than or equal to that of the first material. This helps to more efficiently transfer the heat generated by combustion to part 501. For example, part 102a of engine structure 102 may be formed of iron (which has a thermal conductivity of approximately 80 W / m K) and / or steel (which has a thermal conductivity of approximately 50 W / m K), and heat transfer member 530 may be formed of copper (which has a thermal conductivity of approximately 385 W / m K), aluminum (which has a thermal conductivity of approximately 205 W / m K), and / or brass (which has a thermal conductivity of approximately 109 W / m K). Heat transfer member 530 may be formed via any suitable manufacturing process (e.g., casting, extrusion, and / or milling).

[0437] like Figure 24 As shown, in the illustrated embodiment, the engine 100 includes an insulating material 540 covering the external duct 126a to increase its thermal insulation. The insulating material 540 is more thermally insulating than the material forming the external duct 126a. For example, the insulating material 540 can be formed from a foam material (e.g., polyurethane foam), polystyrene, glass fiber, and / or mineral wool. Similarly, the insulating material 540 can also be used for... Figures 21 to 23 In the heat transfer device 500 shown. In an alternative embodiment (not shown), the insulation material 540 may only cover a portion of the external conduit 126a (e.g., portion 501).

[0438] In some embodiments, the passive heat transfer device 528 may additionally or alternatively include one or more heat pipes, for example, connected to the outer surface 102b of the engine structure 102 and the annular portion 532 (and / or directly connected to portion 501). This configuration of the passive heat transfer device 528 helps to more efficiently transfer the heat generated by combustion from the engine structure 102 to the external duct 126a.

[0439] The above description of one or more embodiments is merely by way of example, and it should be understood that variations may be made without departing from the scope of protection provided by the appended claims.

Claims

1. A gas-fueled internal combustion engine, comprising: Engine structure, including: Crankcase; and An oil reservoir, located below the crankcase; and A ventilation system includes a gas pressure source configured to deliver leaked gas, including the gaseous fuel, from the crankcase as exhaust gas. The ventilation system includes a first oil separator configured to reduce the oil concentration in the exhaust gas. The ventilation system is configured such that, during use, the gas pressure in the crankcase is higher than the gas pressure in the first oil separator. The engine includes a first exhaust duct arranged to deliver oil removed from the exhaust gas by the first oil separator to the oil reservoir. The first discharge conduit is configured to maintain an oil head that applies hydrostatic pressure to the oil in the oil reservoir, thereby suppressing the transport of gas from the crankcase to the oil separator via the first discharge conduit during use.

2. The engine according to claim 1, wherein, The first end of the first discharge conduit is connected to the first oil separator, and the second end of the first discharge conduit is connected to the oil reservoir, wherein the first discharge conduit is configured such that oil flows from the first end to the second end without obstruction by moving parts.

3. The engine according to claim 1 or 2, wherein, The first end of the first discharge conduit is connected to the first oil separator, and the second end of the first discharge conduit is connected to the oil reservoir, wherein the first end is at the level of the crankcase or above the crankcase.

4. The engine according to claim 3, wherein, The engine structure includes a cylinder bank above the crankcase, wherein the first end is at the level of or above the cylinder bank.

5. The engine according to any one of the preceding claims, wherein, The engine structure includes a gearbox, and the first oil separator is mounted adjacent to the gearbox.

6. The engine according to any one of the preceding claims, wherein, The first discharge conduit is arranged to deliver oil adjacent to the bottom of the oil reservoir.

7. The engine according to any one of the preceding claims, wherein, The first exhaust duct is located outside the engine structure.

8. The engine according to any one of the preceding claims, wherein, The gas pressure source is located downstream of the crankcase, and the first oil separator is located upstream of the gas pressure source.

9. The engine according to any one of the preceding claims, wherein, The ventilation system includes a second oil separator configured to reduce the oil concentration in the exhaust gas and configured such that the gas pressure in the crankcase during use is lower than the gas pressure in the second oil separator, and wherein the engine includes a second exhaust duct separate from the first exhaust duct, the second exhaust duct being arranged to deliver oil removed from the exhaust gas by the second oil separator to a portion of the engine structure leading to the oil reservoir; optionally, wherein the second oil separator is a passive (e.g., cyclone) oil separator.

10. The engine according to claim 9, wherein, The gas pressure source is located downstream of the crankcase, and the second oil separator is located downstream of the gas pressure source.

11. The engine according to any one of the preceding claims, wherein, The first oil separator is a passive oil separator.

12. The engine according to any one of the preceding claims, wherein, The gas pressure source is a pump.

13. A gas-fueled internal combustion engine, comprising: Engine structure, including crankcase; and A ventilation system is configured to deliver leaked gas, including the gaseous fuel, from the crankcase as exhaust gas. The ventilation system includes an oil separator configured to reduce the oil concentration in the exhaust gas. The oil separator comprises: The separator section is configured to separate the oil from the exhaust gas; and The outlet section is installed into the separator section. The outlet section includes an oil outlet in fluid communication with the separator section, for discharging the separated oil from the oil separator. The engine structure includes an inlet portion, which includes an oil inlet, and... The outlet portion is installed to the inlet portion, allowing oil leaving the oil outlet to enter the oil inlet, and the separator portion is installed to the engine structure.

14. The engine according to claim 13, wherein, One of the outlet portion and the inlet portion includes a male portion, the male portion including a corresponding oil outlet or oil inlet, and the other of the outlet portion and the inlet portion includes a corresponding female portion, the female portion including a corresponding oil outlet or oil inlet, and wherein the male portion is received in the female portion.

15. The engine according to claim 14, wherein, The male portion includes a male thread, and the female portion includes a corresponding female thread, wherein the outlet portion is installed to the inlet portion via the engagement of the male thread and the female thread.

16. The engine according to claim 15, wherein, The outlet portion includes the male portion, and the inlet portion includes the female portion, wherein the male portion is rotatable relative to the separator portion about the helical axis of the male portion to engage the male thread and the female thread.

17. The engine according to claim 16, wherein, The outlet portion includes a recess that engages with a tool, such as a screwdriver or an Allen wrench, for rotating the male portion about its helical axis; optionally, the recess is opposite the oil outlet.

18. The engine according to any one of claims 13 to 17, wherein, At least a portion of the separator section and at least a portion of the outlet section are formed as a single integral material piece, such that the outlet section is mounted to the separator section; optionally, the separator section includes a truncated conical portion, and wherein the at least a portion of the outlet section and the truncated portion (e.g., its apex) are formed as a single integral material piece.

19. The engine according to any one of claims 13 to 18, wherein, The separator section is adjacent to the inlet section.

20. The engine according to any one of claims 13 to 19, wherein, The outlet section is located substantially below the separator section.

21. The engine according to any one of claims 13 to 20, wherein, The separator section is elongated, and the longitudinal axis of the separator section is substantially perpendicular to the axis of the oil outlet.

22. The engine according to any one of claims 13 to 21, wherein, The maximum length of the outlet section is less than the maximum length of the separator section.

23. The engine according to any one of claims 13 to 22, wherein, The volume of the outlet section is smaller than the volume of the separator section.

24. The engine according to any one of claims 13 to 23, further comprising a sealing device located between the outlet portion and the inlet portion, wherein, The sealing device is configured to suppress oil leakage traveling from the oil outlet toward the oil inlet; optionally, the sealing device includes a sealing member, such as an O-ring.

25. The engine according to any one of claims 13 to 24, wherein, The oil separator is a passive oil separator.

26. The engine according to claim 25, wherein, The oil separator is a cyclone oil separator, which is configured to form a vortex in the discharged gas to separate oil therefrom.

27. The engine according to claim 26, wherein, The separator portion includes a truncated conical portion with a vertex, and the outlet portion is mounted to the vertex.

28. The engine according to any one of claims 13 to 27, wherein, The crankcase includes the oil inlet.

29. The engine according to any one of claims 13 to 28, wherein, The ventilation system is configured such that the gas pressure in the crankcase is lower than the gas pressure in the oil separator.

30. The engine according to any one of claims 13 to 29, wherein, The ventilation system includes a gas pressure source configured to deliver the exhaust gas from the crankcase, and wherein the oil separator is located downstream of the gas pressure source; optionally, the gas pressure source is a pump.

31. The engine according to any one of the preceding claims, wherein, The gaseous fuel is hydrogen.

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