Patent Application
20210277809
This application claims priority to German Application No. DE 10 2020 202 737.4 filed on Mar. 4, 2020, the contents of which are hereby incorporated by reference in its entirety.
The invention relates to a tribological system, a method for producing such a tribological system and an internal combustion engine with such a tribological system.
For some time now, internal combustion engines have been designed with charge exchange members which comprise valves, wherein such valves can be placed on a valve seat ring for closing a charge exchange channel of a respective charge exchange member of the internal combustion engine. In this case, such a valve and the valve seat ring form a tribological system on which typically high requirements are imposed with regard to a wear resistance of the components of the tribological system which can be brought in contact with one another—i.e. the valve and the valve seat ring—as well as a temperature resistance and a chemical resistance of said components. In order to better meet this high requirements, for some time valves have been used which are plated or coated with a plating in the area of a seat area of the respective valve. Frequently high-nickel-content or nickel -based valve materials are used. In these high-nickel-content or nickel-based valve materials, this plating typically has a high cobalt content.
In this case, the high price for cobalt-containing plating materials has a disadvantageous effect on the manufacturing costs of a valve of a tribological system and therefore also on the manufacturing costs of the tribological system per se. In addition, such a usual high-nickel-content valve or valve manufactured from a nickel-based material plated with a high-cobalt-content plating material is difficult to rework mechanically so as to achieve high production tolerances which makes it difficult to produce these valves on a mass scale.
It is therefore an object of the present invention, in particular to eliminate the aforesaid disadvantages, to indicate new ways for a tribological system, for a method for producing such a tribological system and for internal combustion engines with such a tribological system.
The basic idea of the invention is accordingly to use a nickel-based plating material for plating a valve of a tribological system. The main component of the plating material is therefore nickel.
This advantageously has a cost-reducing effect on the manufacturing costs of the valve and therefore also on the tribological system with the valve overall. In addition, the high-nickel-content valve or valve produced from a nickel-based material plated using a nickel-based plating can advantageously be reworked mechanically. Also, the wear behaviour of the tribological system can thus be improved.
A tribological system according to the invention which can preferably be used for a charge exchange member of an internal combustion engine comprises a valve seat ring. The valve seat ring has a first contact surface. In addition, the tribological system comprises a valve which has a second contact surface. The second contact surface of the valve can be placed on the first contact surface of the valve seat ring for closing a valve opening. The second contact surface of the valve is arranged in a seat area of the valve. The valve in the seat area has a seat base having a high nickel content or comprising a nickel-based material, which is plated/coated with a nickel-based plating to form the second contact surface. As already indicated hereinbefore, a cost advantage can thus advantageously be achieved compared with conventional tribological systems. In addition, the valve of the tribological system plated with a nickel-based plating can advantageously be reworked mechanically so that in particular high manufacturing tolerances can be adhered to in an improved manner.
According to a preferred embodiment, the plating contains more than 30 percent by weight, preferably at least 50 percent by weight, most preferably at least 52 percent by weight of nickel. With such a high nickel content, particularly high cost advantages are associated with the manufacture of the plating.
Expediently the nickel-based plating of the valve as additional component, i.e. in addition to the nickel fraction which forms the main component of the plating, comprises up to 3 percent by weight of carbon. Advantageously this improves the sliding properties of the second contact surface present on the valve.
According to an advantageous further development of the tribological system, the nickel-based plating comprises up to 10 percent by weight of iron as an additional component. Thus, a particularly high strength of the plating can advantageously be achieved.
According to a further advantageous further development of the tribological system, the nickel-based plating comprises up to 30 percent by weight of chromium as an additional component. This has an advantageous effect on a corrosion resistance of the plating.
In a further preferred further development of the tribological system, the nickel-based plating comprises up to 9 percent by weight of molybdenum as an additional component. The wear resistance of the plating or the tribological system can thus be advantageously improved.
Particularly preferably the plating consists of the main component nickel and of at least one of the additional components explained hereinbefore as preferred, i.e. carbon, iron, chromium and molybdenum.
The tribological system according to the invention presented here also expressly includes variants which have impurities due to the manufacturing process having a weight fraction of up to 0.2 percent, wherein the impurities are formed by substances which differ from the main component nickel and from the additional components explained hereinbefore.
According to a further advantageous further development of the tribological system, the seat base of the valve having a high nickel content or comprising a nickel-based material comprises a material having the material number 2.4952 or consists of such a material. This enables a particularly heat-resistant configuration of the valve of the tribological system.
According to a further preferred further development of the tribological system, the valve is configured as a poppet valve having a valve disk and a valve stem protruding perpendicularly from the valve disk. In this case, the valve disk comprises the seat base and the plating with the second contact surface. Such a valve is particularly suitable for use of the tribological system in an internal combustion engine.
In a further advantageous further development of the tribological system, the valve seat ring is made of sintered material. Such a valve seat ring is advantageously particularly wear-resistant.
According to a further advantageous further development of the tribological system, the sintered material of the valve seat ring can be obtained by pressing and sintering a powder mixture having a composition explained hereinafter. The powder mixture comprises 5 to 45 percent by weight of one or more iron-based hard phases. In addition, the power mixture comprises 0 to 2 percent by weight of graphite particles, 0 to 2 percent by weight of manganese sulphide, 0 to 2 percent by weight of molybdenum disulphide, 0 to 2 percent by weight of mono-iron phosphide powder. The powder mixture furthermore comprises 0 to 7 percent by weight of copper powder and 0 to 4 percent by weight of cobalt powder. In addition, the powder mixture comprises 0.1 to 1.0 percent by weight of a pressing additive. Furthermore, the powder mixture comprises a high-speed steel having a composition of 14 to 18 percent by weight of chromium, 1.2 to 1.9 percent by weight of carbon, 0.1 to 0.9 percent by weight of silicon, 0.5 to 2.5 percent by weight of vanadium, 0.5 to 2.5 percent by weight of tungsten as well as 0.5 to 2.5 percent by weight of molybdenum. Furthermore, the powder mixture comprises an iron residue as well as impurities due to the manufacturing. The impurities due to the manufacturing in particular comprise nickel, copper, cobalt, calcium and/or manganese with fractions of the residue of <1.5 percent by weight. A valve seat ring comprising such a sintered material is advantageously particularly heat-resistant.
In a further advantageous further development of the tribological system, one or more iron-based hard phases have a composition with less than 0.2 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 8 to 12 percent by weight of chromium as well as 2.2 to 3 percent by weight of silicon. Alternatively, one or more iron-based hard phases have a composition of less than 0.3 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 14 to 20 percent by weight of chromium, 2.9 to 4.2 percent by weight of silicon. A valve seat ring comprising such a sintered material is advantageously particularly wear-resistant.
According to a further advantageous further development of the tribological system, the powder mixture comprises a cobalt-based hard phase having a fraction of 0.5 to 9.9 percent by weight. This advantageously has an effect on the heat resistance of a valve seat ring comprising such a sintered material.
In a further advantageous further development of the tribological system, the sintered material of the valve seat ring can alternatively be obtained by pressing and sintering a powder mixture having the composition indicated hereinafter. The powder mixture comprises one or more cobalt-based hard phases having a composition with less than 0.1 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 7 to 12 percent by weight of chromium as well as 2.0 to 4 percent by weight of silicon. In addition, the powder mixture comprises 0 to 2 percent by weight of graphite particles, 0 to 2 percent by weight of manganese sulphide, 0 to 2 percent by weight of molybdenum sulphide, 0 to 2 percent by weight of monoiron phosphide powder. Furthermore, the powder mixture comprises 0 to 7 percent by weight of copper and 0 to 4 percent by weight of cobalt powder. In addition, the powder mixture comprises 0.1 to 1.0 percent by weight of a pressing additive. Furthermore, the powder mixture comprises high-speed steel having a composition of 14 to 18 percent by weight of chromium, 1.2 to 1.9 percent by weight of carbon, 0.1 to 0.9 percent by weight of silicon, 0.5 to 2.5 percent by weight of vanadium, 0.5 to 2.5 percent by weight of tungsten as well as 0.5 to 2.5 percent by weight of molybdenum. In addition, the powder mixture comprises a residue of cobalt as well as impurities due to the manufacturing. The impurities comprise in particular nickel, copper, calcium and/or manganese with fractions of less than 1.5 percent by weight of the residue. Such a sintered material is in particular characterized by its heat resistance.
Expediently one or more cobalt-based hard phases having a composition of less than 0.2 percent by weight of carbon, 18 to 25 percent by weight of molybdenum, 12 to 20 percent by weight of chromium, 1.0 to 3 percent by weight of silicon is or are present in the powder mixture. A wear resistance of a valve seat ring with such a sintered material can advantageously thus be improved.
Furthermore, the invention relates to a method for producing a tribological system according to the preceding description. This method provides that a seat base of a valve having a high nickel content or comprising a nickel-based material in a seat area of the valve forming a second contact surface of the valve (7), which can be placed on a first contact surface of a valve seat ring of the tribological system is plated/coated with a nickel-based plating. The previously indicated advantages of the tribological system according to the invention are also applied in a similar manner to the method according to the invention for producing such a tribological system.
Furthermore, the invention relates to an internal combustion engine, in particular for a motor vehicle, which comprising a tribological system according to the invention and also described hereinbefore, preferably produced by means of a method according to the invention according to the preceding description. In addition, the internal combustion engine comprises a charge exchange channel which can be closed or released fluidically by means of the tribological system. The tribological system together with the charge exchange channel thus forms a charge exchange member of the internal combustion engine. The advantages of the tribological system according to the invention and of the method for producing such a tribological system according to the invention explained above are also applied in similar manner to the internal combustion engine according to the invention with such a tribological system.
Further important features and advantages of the invention are obtained from the dependent claims, from the drawing and from the relevant description of the figures with reference to the drawing.
It is understood that the features mentioned hereinbefore and to be explained hereinafter can be used not only in the respectively given combination but also in other combinations or alone without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawing and will be explained in further detail in the following description.
The Figure illustrates in axial section a tribological system according to an example.
The only Figure shows schematically in axial section an example of a tribological system 1 according to the invention, which can preferably be used for a charge exchange member 2 of an internal combustion engine 3 according to the invention which is also shown as an example. The tribological system 1 comprises a valve seat ring 5 on which a first contact surface 4 is provided. In addition, the tribological system 1 comprises a valve 7 on which a second contact surface 6 is provided. The second contact surface 6 of the valve 7 can be placed on the first contact surface 4 of the valve seat ring to close a valve opening 8. The second contact surface 6 is arranged in a seat area 9 of the valve 7. In its seat area 9 the valve 7 has a seat base 10 having a high nickel content or comprising a nickel-based material. The seat base 10 of the valve 7 is plated or coated with a nickel-based plating 11 so that the plating 11 forms the second contact surface 6 of the valve 7.
The nickel-based plating 11 has nickel as the main component with more than 30 percent by weight, preferably at least 50 percent by weight, most preferably at least 52 percent by weight. The nickel-based plating 11 has a fraction of carbon of up to 3 percent by weight as additional component. In addition, the nickel-based plating 11 comprises a fraction of iron of up to 10 percent by weight as additional component. Furthermore, the nickel-based plating 11 comprises a fraction of chromium of up to 30 percent by weight. Furthermore, the nickel-based plating 11 has a fraction of molybdenum of up to 9 percent by weight as additional component. The seat base 10 of the valve 7 having a high nickel content or comprising a nickel-based material comprises a material having the material No. 2.4952 or consists of such a material.
Expediently the plating 11 can consist of the main component nickel and of additional components, in the example, carbon, iron, chromium, molybdenum. In all the variants described in it feasible that the plating 11 has impurities due to the manufacturing process having a weight fraction of up to 0.2 percent by weight. In this case, the impurities are formed by substances which differ from the main component nickel and from the previously explained additional components.
The Figure furthermore reveals that the valve 7 is configured as a poppet valve 12. The valve 7 configured as poppet valve 12 comprises a valve disk 13 as well as a valve stem 14 which protrudes substantially perpendicularly from the valve disk 13. In this case, the valve disk 13 comprises the seat base 10 having a high nickel content or comprising a nickel-based material and the plating 11 with the second contact surface 6.
According to the Figure, the valve seat ring 5 is made of a sintered material 15. The sintered material 15 of the valve seat ring 5 can be obtained by pressing and sintering a powder mixture having a composition explained hereinafter. The powder mixture comprises 5 to 45 percent by weight of one or more iron-based hard phases. In addition, the powder mixture comprises 0 to 2 percent by weight of graphite particles, 0 to 2 percent by weight of manganese sulphide, 0 to 2 percent by weight of molybdenum sulphide as well as 0 to 2 percent by weight of mono-iron phosphide powder. Furthermore, the powder mixture comprises 0 to 7 percent by weight of copper powder and 0 to 3 percent by weight of cobalt powder. In addition, the powder mixture comprises 0.1 to 1.0 percent by weight of a pressing additive. The powder mixture additionally has a fraction of high-speed steel having a composition of 14 to 18 percent by weight of chromium, 1.2 to 1.9 percent by weight of carbon, 0.1 to 0.9 percent by weight of silicon, 0.5 to 2.5 percent by weight of vanadium, 0.2 to 2.5 percent by weight of tungsten as well as 0.5 to 2.5 percent by weight of molybdenum. In addition, the powder mixture comprises a residue of iron as well as impurities due to the manufacturing process. Such impurities due to the manufacturing process can comprise copper, cobalt, calcium and/or manganese, wherein the impurities each make up a fraction of less than 1.5 percent by weight of the residue of the powder mixture. One or more of the iron-based hard phases has or have a composition with less than 0.2 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 8 to 12 percent by weight of chromium as well as 2.2 to 3 percent by weight of silicon. Alternatively to the previously explained composition, one or more of the iron-based hard phases has or have a composition with less than 0.3 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 14 to 20 percent by weight of chromium as well as 2.9 to 4.2 percent by weight of silicon. In the example shown in the Figure, a cobalt-based hard phase having a fraction of the powder mixture of 0.5 to 9.9 percent by weight is additionally present in the powder mixture.
The sintered material 15 of the valve seat ring 5 can alternatively be obtained by pressing and sintering a powder mixture having a composition indicated hereinafter. In this case, the powder mixture comprises one or more cobalt-based hard phases having a composition with less than 0.1 percent by weight of carbon, 26 to 32 percent by weight of molybdenum, 7 to 12 percent by weight of chromium as well as 2.0 to 4 percent by weight of silicon. In addition, the powder mixture comprises 0 to 2 percent by weight of graphite particles as well as 0 to 2 percent by weight of manganese sulphide, 0 to 2 percent by weight of molybdenum sulphide and 0 to 2 percent by weight of mono-iron phosphide powder. Furthermore, the powder mixture comprises 0 to 7 percent by weight of copper powder and 0 to 4 percent by weight of cobalt powder. Furthermore, the powder mixture comprises 0.1 to 1.0 percent by weight of a pressing additive as well as high-speed steel having a composition of 14 to 18 percent by weight of chromium, 1.2 to 1.9 percent by weight of carbon, 0.1 to 0.9 percent by weight of silicon, 0.5 to 2.5 percent by weight of vanadium, 0.5 to 2.5 of tungsten as well as 0.5 to 2.5 percent by weight of molybdenum. The powder mixture additionally comprises a residue which is formed by cobalt as well as impurities due to the manufacturing process. Such impurities can be nickel, copper, calcium and/or manganese with fractions in the residue of less than 1.5 percent by weight. In this case, the powder mixture comprises one or more cobalt-based hard phases with a composition of less than 0.2 percent by weight of carbon, 18 to 25 percent by weight of molybdenum, 12 to 20 percent by weight of chromium as well as 1.0 to 3 percent by weight of silicon.
The tribological system 1 shown in the Figure is produced by means of a method according to the invention. According to this method, a seat base 10 of a valve 7 having a high nickel content or comprising a nickel-based material in a seat area 9 of the valve 7 forming a second contact surface 6 of the valve 7, which can be placed on a first contact surface 4 of a valve seat ring 5 of the tribological system 1 is plated or coated with a nickel-based plating 11.
Furthermore, the Figure also shows roughly schematically an internal combustion engine 3, in particular for a motor vehicle. The internal combustion engine 3 comprises a tribological system 1 which is produced in particular by means of the previously explained method according to the invention. In addition, the internal combustion engine 3 comprises a charge exchange channel 16. The charge exchange channel 16 of the internal combustion engine 3 can be closed or released fluidically by means of the tribological system 1 so that the tribological system 1 together with the charge exchange channel 16 form a charge exchange member 2 of the internal combustion engine 3.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020202737.4 | Mar 2020 | DE | national |
