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CN-113530663-B - Longitudinally scavenged large engine

CN113530663BCN 113530663 BCN113530663 BCN 113530663BCN-113530663-B

Abstract

The invention relates to a longitudinally scavenged large engine having at least one cylinder (10) in which a piston (60) is arranged to be movable back and forth along a cylinder axis (X), the cylinder having a cylinder head (20) which together with the piston (60) delimits a combustion chamber (120) for fuel, the large engine being designed to operate in a gas mode in which a premixed air-fuel mixture is combusted in the combustion chamber (120), wherein a plurality of outlet valves (40) are provided in the cylinder head (20) for discharging exhaust gases from the combustion chamber (120), and wherein a projection is provided on the cylinder head (20) between two adjacent outlet valves (40) in each case, which projection extends into the combustion chamber (120).

Inventors

  • D. Im Hassley
  • ALDER ROLAND

Assignees

  • 温特图尔汽柴油公司

Dates

Publication Date
20260505
Application Date
20210326
Priority Date
20200417

Claims (15)

  1. 1. A longitudinally scavenged large engine having at least one cylinder (10) in which a piston (60) is arranged to be movable back and forth along a cylinder axis (X), the cylinder having a cylinder head (20) which together with the piston (60) delimits a combustion chamber (120) for fuel, the large engine being designed to operate in a gas mode in which a premixed air-fuel mixture is combusted in the combustion chamber (120), wherein a plurality of outlet valves (40) are provided in the cylinder head (20) for discharging exhaust gases from the combustion chamber (120), characterized in that a protrusion is provided on the cylinder head (20) between two adjacent outlet valves (40), which protrusion extends into the combustion chamber (120) such that a flow profile is achieved in the cylinder by avoiding or reducing areas with low flow rates in the combustion chamber (120), whereby the amount of exhaust gases remaining in the cylinder can be reduced, whereby all exhaust gases discharged from the combustion chamber and all exhaust gases from the combustion chamber are heat transferred to fresh air are reduced.
  2. 2. The longitudinally scavenged large engine of claim 1, wherein the cylinder (10) has four outlet valves (40) arranged in the cylinder head (20).
  3. 3. A longitudinally scavenged large engine as set forth in claim 2, wherein the four outlet valves (40) are arranged in a rectangular configuration.
  4. 4. A longitudinally scavenged large engine according to any one of claims 1-3, wherein each protrusion (7) extends in a radial direction towards the cylinder axis (X).
  5. 5. A longitudinally scavenged large engine according to claim 4, wherein each protrusion (7) is designed such that its height (H) measured perpendicular to the radial direction decreases when seen towards the cylinder axis (X), and its height is greatest at the radially outer region of the cylinder head and then decreases.
  6. 6. A longitudinally scavenged large engine according to claim 4, wherein each protrusion (7) is designed such that its width (B) measured perpendicular to the radial direction decreases when seen towards the cylinder axis (X), and its width is greatest at the radially outer region of the cylinder head and then decreases.
  7. 7. A longitudinally scavenged large engine according to any one of claims 1-3, wherein each protrusion (7) is essentially designed as a tetrahedron, wherein the base of each tetrahedron is arranged radially outwards and the vertices of the tetrahedron are arranged radially inwards, such that the protrusions (7) are arranged with their vertices towards the cylinder axis (X).
  8. 8. A longitudinally scavenged large engine according to any one of claims 1-3, wherein inspection means are provided which actuate the plurality of outlet valves (40) such that the amount of exhaust gas remaining in the combustion chamber (120) is minimized.
  9. 9. A longitudinally scavenged large engine according to any one of claims 1-3, wherein each outlet valve (40) has a valve axis (a), and wherein at least one outlet valve (40) is arranged such that its valve axis (a) is aligned parallel to the cylinder axis (X).
  10. 10. A longitudinally scavenged large engine according to claim 9, wherein each outlet valve (40) is arranged such that its valve axis (a) is aligned parallel to the cylinder axis (X).
  11. 11. A longitudinally scavenged large engine according to any one of claims 1-3, wherein the plurality of outlet valves (40) are arranged such that the outlet valves (40) are symmetrically arranged about the cylinder axis (X).
  12. 12. A longitudinally scavenged large engine as set forth in any one of claims 1-3 designed as a longitudinally scavenged large diesel engine.
  13. 13. A longitudinally scavenged large engine as set forth in any one of claims 1-3 designed as a longitudinally scavenged two-stroke large engine.
  14. 14. A longitudinally scavenged large engine as set forth in any one of claims 1-3 designed as a longitudinally scavenged two-stroke large diesel engine.
  15. 15. A longitudinally scavenged large engine as set forth in any one of claims 1-3 designed as a dual fuel large diesel engine which can be operated in a liquid mode in which liquid fuel is introduced into the combustion chamber (120) for combustion and which can also be operated in the gas mode in which gas is introduced into the combustion chamber (120) as fuel.

Description

Longitudinally scavenged large engine Technical Field The present invention relates to a longitudinally scavenged large engine. Background Large engines, which may be designed as two-stroke or four-stroke engines, such as longitudinally scavenged two-stroke large diesel engines, are often used as drive units for ships or even in stationary operation (stationary operation), such as for driving large generators to generate electrical energy. Engines are often operated in continuous operation for a considerable period of time, which places high demands on operational safety and usability. Thus, particularly long maintenance intervals, low wear and economical handling of the operating material are central criteria for the operator. Large engines typically have cylinders with an internal diameter (cylinder bore) of at least 200 mm. Today, large engines with cylinder bores up to 960mm or even larger are used. Another important aspect is the energy efficiency and the quality of the exhaust gas, in particular the nitrogen oxide concentration or the sulfur load in the exhaust gas. Another problem is unburned hydrocarbons, such as methane, escaping. In this case, legal requirements and corresponding limit values for the exhaust gas limit values are becoming increasingly stringent. As a result, especially in the case of two-stroke large diesel engines, not only the combustion of traditional heavy fuel oils, which are highly contaminated with pollutants, but also the combustion of diesel or other fuels, such as natural gas, is becoming more and more problematic, as meeting exhaust gas limit values is becoming more and more difficult, technically more complex and therefore more expensive. Regarding economical and efficient operation, compliance with exhaust gas limits and availability of resources, alternatives to heavy fuel oils traditionally used as fuel for large engines are also being sought. Here, both liquid fuel, i.e. fuel introduced into the combustion chamber in liquid state, and gaseous fuel, i.e. fuel introduced into the combustion chamber in gaseous state, are used. Examples of liquid fuels as known alternatives to heavy fuel oils are other heavy hydrocarbons, alcohols (especially methanol or ethanol), gasoline, diesel, or also emulsions or suspensions, especially left over from refineries. For example, an emulsion called MSAR (multiphase ultrafine atomized residue) is known to be used as a fuel. These are essentially emulsions of heavy hydrocarbons produced in a particular process, such as bitumen, heavy fuel oil or the like, and water. Well known suspensions are those of coal dust and water, which are also used as fuel for large engines. For example, natural gas such as LNG (liquefied natural gas) is known as a gaseous fuel. Another known alternative to pure operation with heavy fuel oil is to design large engines in such a way that they can work with two or even more different fuels, where the engine works with one fuel or with another fuel, depending on the working situation or environment. Such large engines, also known as multi-fuel large engines, may be switched from a first mode in which a first fuel is combusted to a second mode in which a second fuel is combusted during operation, and vice versa. A well-known design of large engines that can operate on two different fuels is the type of engine for which the term "dual fuel engine" is currently used. These engines may operate in a gas mode in which a gaseous fuel, such as natural gas or methane, is introduced into the combustion chamber for combustion, on the one hand, and in a liquid mode in which a liquid fuel, such as heavy fuel oil or another liquid fuel, may be combusted in the same engine, on the other hand. These large engines may be two-stroke and four-stroke engines, especially longitudinally scavenged two-stroke large diesel engines. Large engines are also known which can operate on two different liquid fuels, where typically both fuels are stored so that the engine can operate on either the first fuel or the second fuel even during operation. There are also known designs in which two fuels are introduced into the combustion chamber in the same working cycle of a large engine. Large engines that can operate on at least two or even more different liquid or gaseous fuels are typically operated in different modes of operation depending on the fuel currently being used. In an operating mode commonly referred to as diesel operation, combustion of fuel generally occurs according to the principles of compression ignition or auto-ignition of the fuel. In a mode commonly referred to as otto operation, combustion is performed by spark ignition of an ignitable fuel-air mixture. Such spark ignition may be performed by an electric spark, for example with a spark plug, or may also be performed by self-ignition of a small injection quantity of fuel, which then causes spark ignition of another fuel. In the case of the above-described dual fuel engine, for