Layer-sintered valve seat ring, methods for its manufacture, combinations thereof and their use

Abstract

Method for manufacturing a layered sintered valve seat ring, comprising the following steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the carrier material (2) contains: C: 0.5 to 1.8 wt.%; Cr: 3 to 16 wt.%; Mo: 1 to 5% by weight; W: 0.5 to 5.5 wt.%; V: 0.4 to 4.0 wt.%; Cu: 12 to 25 wt.%; Fe: 41.3 to 82.6 wt.%; possibly one or more of Mn: up to 0.6 wt.%; Si: up to 1.8 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order.

Description

[0001] The present invention relates to a layered sintered valve seat ring. The present invention also relates to a method for its manufacture, combinations thereof, and their use.

[0002] From JP 2015-127 520 A, a valve seat made of an iron-based sintered alloy for an internal combustion engine is known, comprising two layers: a top layer and a base layer. The base layer has a thermal conductivity of 23-50 W / m·K at 20-300 °C, while the top layer has a thermal conductivity of 10-22 W / m·K at 20-300 °C. The top layer forms the valve contact surface.

[0003] From DE 199 42 780 A1, a cylinder head for a piston internal combustion engine made of cast iron with vermicular graphite is known, with at least one gas inlet channel with at least one associated inlet valve and at least one gas outlet channel with at least one associated outlet valve per cylinder.

[0004] From DE 10 2016 109 539 A1, a valve seat ring with a support layer and a functional layer is known, wherein the support layer consists of a hardened copper matrix containing 0.25 to 20 wt.% of a hardening component, and wherein the functional layer consists of a hardened copper matrix containing 5 to 25 wt.% of a hard phase based on the copper matrix.

[0005] The use of layered sintered valve seat rings with a carrier material and a functional material is known. Typically, an expensive functional material is combined with a cost-effective carrier material, thereby reducing the material costs for a valve seat ring. The interface between the carrier material and the functional material can be arranged either orthogonally or at a specific angle to the axis of the valve seat ring (in its axial direction).

[0006] Valve seat rings are generally installed in the cylinder head as an interference fit, i.e., there is an overlap between the valve seat ring outer diameter and the diameter of the receiving bore in the cylinder head, which is usually 40 µm to 120 µm.

[0007] While the use of layered sintered valve seat rings in combination with an aluminum alloy cylinder head is generally unproblematic, problems with valve seat relaxation can occur when using cylinder heads made of cast iron alloys (for example, cast iron with lamellar graphite (GJL), cast iron with vermicular graphite (GJV), or cast iron with spheroidal graphite (GJS)). Relaxation is a plastic deformation or thermal creep of the valve seat ring material when hot (i.e., during operation). This causes the outer diameter of the valve seat ring to decrease when cooled, and the valve seat ring loses some of its contact / press fit in the cylinder head bore. This can eventually lead to the valve seat ring loosening or detaching from the cylinder head, resulting in engine damage.

[0008] In particular, the use of layered sintered valve seat rings can lead to greater relaxation of the valve seat rings, since the favorable carrier material generally has a lower creep resistance than the functional material and thus the overlap / press fit can be lost relatively quickly.

[0009] The object of the invention is to provide a layered sintered valve seat ring for use in cylinder heads made of cast iron alloys, in which relaxation is reduced compared to conventional layered sintered valve seat rings. Furthermore, a method for its production, combinations thereof, and a use of these combinations are to be provided.

[0010] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0011] The present invention is based on the general concept of designing the support material in a layered valve seat ring such that its relaxation is reduced compared to conventional layered valve seat rings to such an extent that loosening or detachment of the layered valve seat ring from the cylinder head during operation is prevented. In particular, a layered valve seat ring is designed to comprise at least two materials, wherein one material is a functional material for tribological contact with a mating component and the other material is a support material for the functional material, the support material containing: C: 0.5 to 1.8 wt.%; Cr: 3 to 16 wt.%; Mo: 1 to 5 wt.%; W: 0.5 to 5.5 wt.%; V: 0.4 to 4.0 wt.%; Cu: 12 to 25 wt.%; Fe: 41.3 to 82.6 wt.%; optionally one or more of Mn: up to 0.6 wt.%; Si: up to 1.8 wt.-%; the remainder being manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may each be present in proportions of <0.3 wt.%.

[0012] In an advantageous embodiment of the solution according to the invention, the carrier material contains: C: 1.0 to 1.8 wt.%; Cr: 10 to 15 wt.%; Mo: 2.5 to 5 wt.%; W: 0.8 to 1.5 wt.%; Si: 0.2 to 1.8 wt.%; V: 0.4 to 1.5 wt.%; Cu: 12 to 25 wt.%; Fe: 47.8 to 73.1 wt.%; optionally Mn: up to 0.6 wt.%; wherein the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each.

[0013] In an advantageous embodiment of the solution according to the invention, the carrier material contains: C: 0.7 to 1.1 wt.%; Cr: 3 to 5 wt.%; Mo: 3 to 5 wt.%; W: 3.5 to 5.5 wt.%; V: 1.0 to 2.0 wt.%; Cu: 15 to 25 wt.%; Fe: 54.8 to 73.8 wt.%; optionally one or more of Mn: up to 0.6 wt.%; Si: up to 1.0 wt.%; wherein the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may optionally be present in proportions of <0.3 wt.% each.

[0014] In an advantageous embodiment of the solution according to the invention, the carrier material contains: C: 1.0 to 1.8 wt.%; Cr: 12 to 16 wt.%; Mo: 1 to 2.5 wt.%; W: 0.8 to 2.0 wt.%; Si: 0.2 to 1.2 wt.%; V: 0.4 to 1.5 wt.%; Cu: 12 to 25 wt.%; Fe: 49.4 to 72.6 wt.%; optionally Mn: up to 0.6 wt.%; wherein the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may optionally be present in proportions of <0.3 wt.% each.

[0015] In an advantageous embodiment of the solution according to the invention, the functional material contains: C: 0.7 to 1.5 wt.%; Cr: 2 to 4 wt.%; Mo: 12 to 18 wt.%; W: 2 to 4 wt.%; V: 1 to 2 wt.%; Cu: 10 to 20 wt.%; Co: 6 to 14 wt.%; Fe: 34.5 to 66.3 wt.%; optionally Mn: up to 1.0 wt.%; Si: up to 1 wt.%; wherein the remainder consists of manufacturing-related impurities in the form of Ni, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each.

[0016] The present invention further provides a combination of a valve seat ring, manufactured according to the inventive method described below, and a valve, wherein the valve is armored or nitrided.

[0017] The present invention further provides a combination of a valve seat ring, manufactured according to the inventive method described below, and a valve, wherein the valve is made of a nickel-based alloy or an iron-based alloy with a Ni content of 10 to 40 wt.%.

[0018] The present invention further provides a combination of a valve seat ring, manufactured according to the inventive method described below, and a cylinder head made of a cast iron alloy, wherein the cast iron alloy contains lamellar graphite, vermicular graphite or spheroidal graphite, and wherein the valve seat ring is inserted into the cylinder head with an interference fit.

[0019] The present invention provides a method according to the invention for producing a layered sintered valve seat ring, comprising the steps of: producing starting material powders for a carrier material and a functional material with compositions as specified above; uniaxial pressing of the starting material powders; sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat-treating the sintered material by tempering or quenching.

[0020] According to the invention, uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s.

[0021] According to the invention, sintering is carried out for a period of time in the range of 10 min to 30 min at sintering temperature.

[0022] According to the invention, heat treatment is carried out by tempering, wherein the tempering is preferably carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order.

[0023] In an advantageous embodiment of the present invention, one of the aforementioned combinations is used in an internal combustion engine that is partially or completely operated with hydrogen as fuel gas.

[0024] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0025] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0026] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0027] Each of these shows, schematically Fig. 1 a sectional view through a valve seat ring according to the invention with an interface between functional material and support material extending orthogonally to the valve seat ring axis, Fig. 2 a sectional view through a valve seat ring according to the invention with an interface between functional material and support material that is not orthogonal to the valve seat ring axis, and Fig. 3 diagrams showing the overlap between a valve seat ring material and a receiving bore in a cylinder head after engine tests

[0028] According to the Fig. 1. According to one embodiment of the invention, a valve seat ring comprises a functional material (1) and a support material (2). A boundary surface (4) extending orthogonally to the valve seat ring axis (5) exists between the functional material (1) and the support material (2). The angle (6) between the functional material (1) and the support material (2) is accordingly 90°. As shown in the Fig. As shown in Figure 1, the valve seat ring is fitted into a cylinder head (3) by means of an interference fit, which is represented by the interference fit interface (7). The contact fit overlap is typically in the range of 40 µm to 120 µm, preferably in the range of 50 µm to 110 µm, and particularly in the range of 70 µm to 100 µm.

[0029] The Fig. Figure 2 shows a valve seat ring according to a further embodiment of the invention. The valve seat ring according to the Fig. 2 is essentially related to the valve seat ring according to the Fig. 1 identical, except that the interface between the functional material (1) and the support material (2) is non-orthogonal to the valve seat ring axis (5). In particular, the angle (6) between the functional material (1) and the support material (2) is less than 90°, for example between 35° and 70°, preferably between 45° and 55°. This has the advantage that the contact area of ​​the support material (2) to the cylinder head (3) is increased and at the same time the required amount of the expensive functional material (1) can be reduced, leading to a cost reduction.

[0030] The valve seat ring according to the invention can be manufactured in particular using the following method.

[0031] In a first step, starting material powders for the carrier material 2 and the functional material 1 are produced with compositions as specified above. These starting material powders are then uniaxially pressed, preferably at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C, and for a time in the range of 0.5 s to 1.8 s. One of the starting material powders can undergo pre-compaction by uniaxial pressing before the final joint compaction. This allows the interface between the carrier and the functional material to be compacted. Fig. 1 and Fig. 2 can be preset to a desired angle in relation to the valve seat ring axis as shown.

[0032] The uniaxially pressed starting material powder is then sintered under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C, with the sintering preferably being carried out for a time in the range of 10 min to 30 min.

[0033] Finally, the sintered material undergoes heat treatment by tempering or quenching. Tempering is preferably carried out by hardening at 850 °C to 950 °C, oil quenching, and tempering at 510 °C to 610 °C in that order. Tempering is preferably carried out by heating at 550 °C to 620 °C.

[0034] The valve seat ring according to the invention is preferably used in combination with an armored or nitrided valve as the mating component. Alternatively, it can be used as a valve seat ring in combination with a valve made of a nickel-based alloy or an iron-based material with a nickel content of 10-40 wt.% as the mating component. Examples

[0035] Examples of the present invention are described below in the form of two fired engine tests. In each case, the outer diameter of the valve seat rings was measured in three planes after the engine test, and the receiving bore in the cylinder head was also measured in three planes. From this, the overlap of the respective valve seat ring in the planes was then calculated. Engine test 1

[0036] Engine test 1 was a high-performance load cycle with a running time of 1063 hours at a rated power of 260 kW (engine with a 7.7 L displacement). This customer-specific cyclic endurance test was performed with a high proportion of full load operation. The support material was a material according to claim 2, and the functional material was a material according to claim 5. The angle (6) between the functional and support materials was approximately 90°. The cylinder head material was lamellar graphite cast iron (GJL). The initial overlap between the valve seat ring and the cylinder head was 40 to 60 µm, and the outer diameter of the valve seat ring was 40.068 ± 0.008 mm. The comparison material was the cast material PL 500. To compare the material according to the invention with the comparison material made of cast iron, the mean value of 4 VSR exhaust valve seat rings each was calculated. Engine test 2

[0037] Engine test 2 was a customer-specific "cold-warm endurance test" with a running time of 264 hours (engine with a displacement of 12.8 liters). The support material was a material according to claim 2, and the functional material was a material according to claim 5. The angle (6) between the functional and support materials was 60 to 68°. The cylinder head material was lamellar graphite cast iron (GJL). The initial overlap between the valve seat ring and the cylinder head was 50 to 70 µm, and the outer diameter of the valve seat ring was 43.078 ± 0.008 mm. The reference material was the sintered material PLS 259. To compare the material according to the invention with the reference cast material, the average value of three VSR exhaust valve seat rings was calculated.

[0038] In the Fig. Figure 3 shows the respective coverage in areas A, B, and C of the respective valve seat ring in comparison to a conventional cast material or a conventional sintered material. From the Fig. 3 shows that the coverage after the tests is higher for the material according to the invention than for the respective comparison material.

Claims

[1] Method for producing a layered sintered valve seat ring comprising the steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the carrier material (2) contains: C: 0.5 to 1.8 wt.%; Cr: 3 to 16 wt.%; Mo: 1 to 5% by weight; W: 0.5 to 5.5 wt.%; V: 0.4 to 4.0 wt.%; Cu: 12 to 25 wt.%; Fe: 41.3 to 82.6 wt.%; possibly one or more of Mn: up to 0.6 wt.%; Si: up to 1.8 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order. [2] Method for producing a layered sintered valve seat ring comprising the steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the carrier material (2) contains: C: 1.0 to 1.8 wt.%; Cr: 10 to 15 wt.%; Mo: 2.5 to 5% by weight; W: 0.8 to 1.5 wt.%; Si: 0.2 to 1.8 wt.%; V: 0.4 to 1.5 wt.%; Cu: 12 to 25 wt.%; Fe: 47.8 to 73.1 wt.%; if applicable Mn: up to 0.6 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order. [3] Method for producing a layered sintered valve seat ring comprising the steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the carrier material (2) contains: C: 0.7 to 1.1 wt.%; Cr: 3 to 5 wt.%; Mo: 3 to 5% by weight; W: 3.5 to 5.5 wt.%; V: 1.0 to 2.0 wt.%; Cu: 15 to 25 wt.%; Fe: 54.8 to 73.8 wt.%; possibly one or more of Mn: up to 0.6 wt.%; Si: up to 1.0 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order. [4] Method for producing a layered sintered valve seat ring comprising the steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the carrier material (2) contains: C: 1.0 to 1.8 wt.%; Cr: 12 to 16 wt.%; Mo: 1 to 2.5% by weight; W: 0.8 to 2.0 wt.%; Si: 0.2 to 1.2 wt.%; V: 0.4 to 1.5 wt.%; Cu: 12 to 25 wt.%; Fe: 49.4 to 72.6 wt.%; if applicable Mn: up to 0.6 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Co, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order. [5] Method for producing a layered sintered valve seat ring according to any one of claims 1 to 4, comprising the steps: Production of starting material powders for a carrier material (2) and a functional material (1) wherein the functional material (1) is for tribological contact with a counter-runner and a material is the carrier material (2) for the functional material (1), wherein the functional material (1) contains: C: 0.7 to 1.5 wt.%; Cr: 2 to 4 wt.%; Mo: 12 to 18% by weight; W: 2 to 4 wt.%; V: 1 to 2 wt.%; Cu: 10 to 20 wt.%; Co: 6 to 14 wt.%; Fe: 34.5 to 66.3 wt.%; if applicable Mn: up to 1.0 wt.%; Si: up to 1 wt.%; the remainder consists of manufacturing-related impurities in the form of Ni, Ca, P and / or S, which may be present in proportions of <0.3 wt.% each, uniaxial pressing of the starting material powders; Sintering of the uniaxially pressed starting material powders under an endogas atmosphere or a nitrogen-hydrogen atmosphere at a temperature in the range of 1055 °C to 1152 °C; and heat treatment of the sintered material by tempering, where the uniaxial pressing is carried out at a pressure in the range of 40 MPa to 140 MPa, at a temperature in the range of 12 °C to 60 °C and for a time in the range of 0.5 s to 1.8 s, the sintering process is carried out for a period of time ranging from 10 to 30 minutes, where the heat treatment is carried out by tempering and where the tempering process is carried out by hardening at 850 °C to 950 °C, oil quenching and tempering at 510 °C to 610 °C in that order. [6] Combination of a valve seat ring obtained according to a method according to one of claims 1 to 5 and a valve, wherein the valve is armored or nitrided. [7] Combination of a valve seat ring obtained according to a method according to one of claims 1 to 5 and a valve, wherein the valve is made of a nickel-based alloy or an iron-based alloy with a Ni content of 10 to 40 wt.%. [8] Combination of a valve seat ring obtained according to a method according to one of claims 1 to 5 and a cylinder head (3) made of a cast iron alloy, wherein the cast iron alloy contains lamellar graphite, vermicular graphite or spheroidal graphite, and wherein the valve seat ring is inserted into the cylinder head (3) by an interference fit. [9] Use of a combination according to any one of claims 6 to 8 in an internal combustion engine that is partially or completely powered by hydrogen as fuel gas.

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