WO2017089645A1

WO2017089645A1 - A method of manufacturing a prechamber element for an internal combustion piston engine, a use of a base material in a prechamber element and a prechamber element for an internal combustion piston engine

Info

Publication number: WO2017089645A1
Application number: PCT/FI2015/050830
Authority: WO
Inventors: Jarkko Laine
Original assignee: Wärtsilä Finland Oy
Priority date: 2015-11-27
Filing date: 2015-11-27
Publication date: 2017-06-01

Abstract

Invention relates to a method of manufacturing a prechamber element for an internal combustion piston engine, wherein a porous base material is formed to comprise an interconnected network of pores such that the porosity of the base material is maintained as of open porosity, and whereinafter the forming the open porosity base material, the base material (20) is impregnated with a liquid aluminum such that the interconnected pores in the porous material are filled (22), the liquid aluminum is solidified in the pores, and the base material is shaped to the form of the prechamber element unit. Invention relates also to a use of a base material in a prechamber element and a prechamber element for an internal combustion piston engine.

Description

A method of manufacturing a prechamber element for an internal combustion piston engine, a use of a base material in a prechamber element and a prechamber element for an internal combustion piston engine

Technical field

[001 ] The present invention relates to method of manufacturing a prechamber element for an internal combustion piston engine. Invention relates also to a use of a base material in a prechamber element and a prechamber element for an internal combustion piston engine.

Background art

[002] Internal combustion piston engines can be provided with prechambers, also called as precombustion chambers. The engine provided with such a pre- chamber is called as a prechamber engine. In prechamber engines, each cylinder is provided with a prechamber, and a portion or all of the fuel may be introduced directly into the prechamber. Depending on the engine, the fuel can be self-ignited, or a spark plug or some other device can be used for igniting the fuel. Thus the combustion starts in the prechamber, but main part of the com- bustion takes place in the cylinder of the engine, outside the prechamber. The prechamber construction is beneficial especially in lean burn engines, where part of the fuel is introduced into the prechamber and part of the fuel is mixed with the air before the intake valves. This kind of arrangement can be used, for instance, in spark ignited gas engines. The gas-air mixture in the prechamber is rich compared to the mixture in the cylinder. The rich mixture in the prechamber is ignited by a spark plug and the flames from the prechamber ignite the mixture in the cylinder.

[003] Good high-temperature corrosion resistance is needed from the materials of the prechamber. Similar properties are needed also in other engine components, such as exhaust valves and the turbine blades of turbo- chargers, and in many other applications, especially in machinery, where components are in contact with hot gases containing certain contaminants. In engines, the sodi- um content of the fuel together with the sulphur and vanadium contents are major factors contributing to hot corrosion.

[004] Typically, the prechambers are made of heat resistant steel or a super- alloy. Examples of typical super-alloys used for manufacturing prechamber components are FeCr- or Ni/Co-based super-alloys.

[005] Publication WO2015086893A1 discloses a Fe-based ferro-aluminide intermetallic composition for use in a prechamber component of a piston engine, comprises at least 55 percent by weight of iron, 10 to 40 percent by weight of aluminum, and at least one of the substances selected from the group of B, C, Cr, Zr, Nb, Ti; the total amount of the substances selected from the group not exceeding 5 percent by weight. Also a method for manufacturing a prechamber component comprises a step of manufacturing a prechamber component or a component preform by a powder metallurgical process from the said Fe-based composition

[006] Despite of the use of the super-alloys, hot corrosion is the limiting factor for the lifetime of the prechamber. Also, the materials conventionally used in the prechambers are relatively expensive. The lifetime of the prechamber is effected by the durability of the materials used in the prechamber.

[007] An object of the invention is to provide a prechamber element and a method of manufacturing a prechamber element prechamber which provides increased durability compared to the prior art solutions.

[008] An object of the invention is also to provide a use of a base material in a prechamber element by means of which the durability of the prechamber element is increased.

Disclosure of the Invention

[009] The objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[0010] According to an embodiment of the invention a prechamber element for an internal combustion piston engine is manufactured such that a base material is formed of metal powder to comprise an interconnected network of pores. [001 1 ] The base material may be manufactured by methods known as such. For example sintering of powder has been found to be advantageous method. The base material is manufactured such that the porosity of the base material is maintained as of open porosity, the porosity being advantageously 60% - 90%.

[0012] After the forming the open porosity base material, the base material is impregnated with a liquid aluminum such that the interconnected pores in the porous material are filled with the liquid aluminum is solidified in the pores. Now the base material is shaped to take the final form of the prechamber element.

[0013] This way the thermal conductivity of the prechamber element is im- proved and the thermal stresses are decreased.

[0014] The powder comprises mixture of iron, chromium and/or nickel. The contents of the components of the powder are iron 0-100 %, Chromium 0-50% and nickel 0-50%.

[0015] Aluminum oxide layer is arranged on the surfaces of the prechamber which protects surfaces against oxidation and corrosion.

[0016] The interconnected network of pores filled with the liquid aluminum is substantially evenly distributed in the base material. This way the effect of the matrix of aluminum is maximized.

[0017] The objects of the invention can be met by use of a base material com- prising a porous material with open porosity where an interconnected network of pores are filled with aluminum, in a prechamber element of an internal combustion engine for improving thermal durability of the prechamber component.

[0018] In other word the base material comprises a matrix of interconnected network of aluminum, which is advantageously substantially evenly distributed in the base material.

[0019] According to an embodiment of the invention the prechamber element is a part of a pre-combustion chamber of an internal combustion piston engine.

[0020] According to another embodiment of the invention the prechamber element is a pre-combustion chamber of an internal combustion piston engine.

[0021 ] The porous material is a mixture of iron, chromium and/or nickel. [0022] According to an embodiment of the invention in the use of a base material the interconnected network of pores in the base material is substantially evenly distributed in the base material.

[0023] A prechamber for an internal combustion piston engine according to the invention comprises a body where a prechamber has been formed, wherein the body is of a porous material with open porosity where an interconnected network of pores is filled with aluminum, such that the body material is impregnated with a liquid aluminum and the liquid aluminum is solidified in the pores.

[0024] In a porous base material the porosity will consist of isolated pores, and is referred to as the "closed porosity", and of pores which will form an interconnected network that intersects the surface of the material, which is referred to as the "open porosity". In this connection the pore means a small structural space in the base material filled with either gas, liquid or solid material other than the base material depending on the technical context.

[0025] There are common methods of impregnating the base material with liquid aluminum, including Dry Vacuum and Pressure, Wet Vacuum and Pressure, Wet Vacuum and Internal Impregnation or Pressure Method which are known as such for a skilled person in the art.

Brief Description of Drawings

[0026] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which

Figure 1 illustrates schematically the steps of the method of manufacturing a prechamber element according to an embodiment of the invention, and

Figure 2 illustrates a prechamber element in an internal combustion piston engine according to an embodiment of the invention. Detailed Description of Drawings

[0027] Figure 1 depicts schematically the steps of the method of manufacturing a prechamber element. The steps explained here are such that closely relate to the invention and there may be steps preceding and succeeding the steps shown here. Firstly a porous base material is formed advantageously of metal powder to comprise an interconnected network of pores. The porous base material has a porosity of the base material is maintained as of open porosity during the formation phase. In the first step 10 shown in the figure 1 the porous base material is formed to comprise an interconnected network of pores such that the porosity of the base material is maintained as of open porosity. The base material is formed advantageously by sintering of metal powder. The porosity is controlled to be between 60 - 90%.

[0028] As the second step 12 in the method the base material is impregnated with a liquid aluminum such that the interconnected pores in the porous material are filled. The base material and the liquid aluminum are heated to and maintained at a temperature at which the aluminum is in melted state. After the impregnation is complete enough the base material and the aluminum is allowed to cool whereas the aluminum solidifies in the pores of the base material. Aluminum creates aluminum oxide layer to the all surfaces and protects surfaces against oxidation and corrosion. Aluminum creates also continuous network over the thickness of the base material, which improves the thermal conductivity of the base material in great extent and that way improves its durability against thermal loads.

[0029] In the next step 14 the liquid aluminum is solidified in the pores of the base material after which the base material is shaped to the form of the prechamber element 16. The aluminum may be pure aluminum, with traces of other substances or an aluminum alloy.

[0030] Shows the structure of the base material used in the prechamber ac- cording to the invention. The base material comprises a porous material 20 where an interconnected network of pores is filled with aluminum 22. The aluminum extends through the thickness of the material. This way the thermal conductivity of the material is improved and the thermal durability of the pre- chamber element made of the base material and the interconnected network of pores filled with aluminum.

[0031 ] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred em- bodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.

Claims

1 . Method of manufacturing a prechamber element for an internal combus- tion piston engine, wherein

a porous base material is formed to comprise an interconnected network of pores such that the porosity of the base material is maintained as of open porosity, and wherein

after the forming the open porosity base material, the base material is impregnated with liquid aluminum such that the interconnected pores in the porous material are filled,

the liquid aluminum is-solidified in the pores, and

the base material is shaped to the form of the prechamber element.

2. Method of manufacturing a prechamber element according to claim 1 , characterized in that the base material is formed of metal powder comprising a mixture of iron, chromium and/or nickel.

3. Method of manufacturing a prechamber element according to claim 2, characterized in that the contents of the components are iron 0-100 %, Chromium 0-50% and nickel 0-50%.

4. Method of manufacturing a prechamber element according to claim 1 , characterized in that aluminum oxide layer is arranged on the surfaces of the prechamber which protects surfaces against oxidation and corrosion.

5. Method of manufacturing a prechamber element according to claim 1 , characterized in that the interconnected network of pores filled with the alumi- num is substantially evenly distributed in the base material.

6. Method of manufacturing a prechamber element according to claim 1 , characterized in that the porosity of the base material is controlled to be 60 - 90%.

7. Use of a base material comprising a porous material with open porosity where an interconnected network of pores are filled with aluminum, in a prechamber element of an internal combustion engine for improving thermal durability of the prechamber component.

8. Use of a base material according to claim 7, characterized in that the porous material is a mixture of iron, chromium and/or nickel.

9. Use of a base material according to claim 7, characterized in that the interconnected network of pores is substantially evenly distributed in the base material.

10. A prechamber element for an internal combustion piston engine comprising a body where a prechamber has be formed, wherein the body is of a porous material with open porosity where an interconnected network of pores are filled with aluminum.