Nozzle member, variable nozzle mechanism of variable displacement turbocharger, variable displacement turbocharger, and method for manufacturing nozzle member

Abstract

The nozzle member of at least one embodiment of the present disclosure is a nozzle member included in a variable nozzle mechanism of a variable capacity turbocharger. The nozzle member is composed of an iron-based alloy. In a case where a total value of a carbon content and a nitrogen content of the nozzle member is set as A mass%, and a total value of 0.5 times a tungsten content and a molybdenum content is set as B mass%, a relationship indicated by the following expression is satisfied: 6.6 x A + B ≥ 8.0. A value of the total value B is 1.5 mass% or more.

Description

Technical Field

[0001] This disclosure relates to a nozzle component, a variable nozzle mechanism for a variable capacity turbocharger, a variable capacity turbocharger, and a method for manufacturing the nozzle component. Background Technology

[0002] In turbocharged internal combustion engines, in order to match the exhaust gas flow rate from the internal combustion engine with the gas flow rate that is the optimal operating condition for the turbocharger, variable capacity exhaust turbochargers have been widely used in recent years. These turbochargers allow the flow area of ​​the exhaust gas delivered from the vortex-shaped passage to the turbine to vary according to the operating conditions of the internal combustion engine.

[0003] In a variable displacement exhaust turbocharger, a variable nozzle mechanism is provided to transmit the driving force from the actuator to the nozzle blades via a connecting rod, thereby changing the blade angle of the nozzle blades.

[0004] In such a variable nozzle mechanism, since the driving component that drives the nozzle blades has a sliding part, there are problems such as wear of the sliding part.

[0005] For example, in the variable nozzle mechanism described in Patent Document 1, wear is suppressed by drilling the shape of the contacting parts (see Patent Document 1).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 4875602 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In addition to focusing on the shape of the variable nozzle mechanism, such as that described in Patent Document 1, efforts are also required to improve the wear resistance of the material itself in high-temperature environments.

[0011] In view of the above, at least one embodiment of this disclosure aims to improve the wear resistance of the nozzle components included in the variable nozzle mechanism of a variable capacity turbocharger under high temperature conditions.

[0012] Solution for solving the problem

[0013] (1) The nozzle component of at least one embodiment of this disclosure is the nozzle component included in the variable nozzle mechanism of a variable capacity turbocharger.

[0014] The nozzle component is made of an iron-based alloy.

[0015] Let the total value of carbon content and nitrogen content be set as A mass%.

[0016] If we set the total value of 0.5 times the tungsten content and the molybdenum content as B (mass%),

[0017] Satisfy the following formula:

[0018] 6.6 × A + B ≥ 8.0

[0019] The relational expression represented,

[0020] The total value B is 1.5% by mass or more.

[0021] (2) The variable nozzle mechanism of the variable capacity turbocharger of at least one embodiment of the present disclosure includes:

[0022] First component;

[0023] The second component is slidable relative to the first component;

[0024] The first component is the nozzle component described in (1) above.

[0025] (3) The variable capacity turbocharger of at least one embodiment of the present disclosure has the variable nozzle mechanism described in (2) above.

[0026] (4) The method for manufacturing a nozzle component according to at least one embodiment of the present disclosure is a method for manufacturing a nozzle component included in a variable nozzle mechanism of a variable capacity turbocharger, the method for manufacturing the nozzle component comprising:

[0027] The process of forming the nozzle component described in (1) above by casting or by processing sheet metal.

[0028] Invention Effects

[0029] According to at least one embodiment of this disclosure, the wear resistance of the nozzle components included in the variable nozzle mechanism of a variable capacity turbocharger is improved in high-temperature environments. Attached Figure Description

[0030] Figure 1 This is a cross-sectional view of a variable capacity turbocharger implementation.

[0031] Figure 2 yes Figure 1 BB cross-sectional view.

[0032] Figure 3 yes Figure 2 AA sectional view.

[0033] Figure 4A It is a graph showing the results of wear resistance tests on iron-based alloys under high-temperature conditions.

[0034] Figure 4B It is a graph showing the results of wear resistance tests on iron-based alloys under high-temperature conditions.

[0035] Figure 4C It is a graph showing the results of wear resistance tests on iron-based alloys under high-temperature conditions.

[0036] Figure 4D It is a graph showing the results of wear resistance tests on iron-based alloys under high-temperature conditions.

[0037] Figure 5 This is a table showing the results of wear resistance tests on iron-based alloys under high-temperature conditions.

[0038] Figure 6A This is a flowchart illustrating the manufacturing of nozzle components in several embodiments via casting.

[0039] Figure 6B This is a flowchart illustrating several embodiments of nozzle components manufactured from sheet metal such as rolled material. Detailed Implementation

[0040] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangements of the constituent components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure, but are merely illustrative examples.

[0041] For example, expressions indicating relative or absolute configurations such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric" or "coaxial" not only precisely indicate such configurations, but also indicate the state of relative displacement by angle or distance with tolerances or to the extent that the same function can be obtained.

[0042] For example, expressions indicating that things are "the same", "equal" and "homogeneous" are equal not only indicate a state of strict equality, but also indicate a state of difference where there is a tolerance or a degree of difference in the ability to achieve the same function.

[0043] For example, expressions representing shapes such as quadrilaterals or cylinders not only refer to shapes in a strictly geometric sense, but also include shapes with concave or convex parts or chamfers within the range that can achieve the same effect.

[0044] On the other hand, expressions such as “possessing,” “equipped,” “having,” “including,” or “having” a constituent element are not exclusive expressions that exclude the existence of other constituent elements.

[0045] (Overall structure of a variable capacity turbocharger)

[0046] Figure 1 This is a cross-sectional view of a variable capacity turbocharger implementation. Figure 2 yes Figure 1 BB cross-sectional view. Figure 3 yes Figure 2 AA sectional view. First, based on Figures 1-3 The basic structure of the variable nozzle mechanism 10 of a variable capacity turbocharger 1 according to one embodiment will be described.

[0047] like Figure 1 As shown, in one embodiment of the variable capacity turbocharger 1, the turbine housing 16 housing the turbine rotor 12 and the bearing housing 18 housing the bearing 22 are fastened, for example, by bolts or the like, the bearing 22 rotatably supporting the rotating shaft 12a of the turbine rotor 12. Furthermore, although not shown, on the opposite side of the turbine housing 16, which is separated from the bearing housing 18, the compressor housing housing, which houses the compressor rotor connected to the rotating shaft 12a, is connected to the bearing housing 18.

[0048] On the outer periphery of the turbine housing 16, a vortex-shaped exhaust gas passage 20 is formed, which communicates with an exhaust manifold (not shown) and allows exhaust gas from the engine to flow. In addition, a variable nozzle mechanism 10 for controlling the flow of exhaust gas acting on the turbine rotor 12 is disposed between the vortex-shaped exhaust gas passage 20 and the turbine rotor 12.

[0049] (Variable nozzle mechanism 10)

[0050] like Figure 1 As shown, in one embodiment, the variable nozzle mechanism 10, when sandwiched between the turbine housing 16 and the bearing housing 18, secures the nozzle mounting portion 2 to the bearing housing 18 using bolts or the like, thereby fixing it to the bearing housing 18. Additionally, as... Figure 3 The variable nozzle mechanism 10 shown has one end of a columnar nozzle support 6 connected to one side 2a of the nozzle mounting portion 2. Additionally, one side 4a of a nozzle plate 4 is connected to the other end of the nozzle support 6. In the top view, multiple nozzle support members 6 are circumferentially connected to both the side 2a of the nozzle mounting portion 2 and the side 4a of the nozzle plate 4. Thus, the nozzle plate 4 is supported so that it is detached from the side 2a of the nozzle mounting portion 2.

[0051] In addition, such as Figure 2 as well as Figure 3As shown, a drive ring 5, shaped like a disc, is rotatably disposed on the other side 2b of the nozzle mounting portion 2. Furthermore, a plurality of rod plates 3 are connected to one end of the drive ring 5. Specifically, a plurality of grooves 5a are formed circumferentially along the outer periphery of the drive ring 5, and a connecting shaft portion 3a provided on one end of the rod plate 3 engages with the grooves 5a. It should be noted that the connecting shaft portion 3a can be a protrusion extending from one end of the rod plate 3 toward the nozzle mounting portion 2, or it can be a shaft-like component mounted on one end of the rod plate 3.

[0052] The other end of the rod plate 3 is connected to the nozzle blade assembly 8. Specifically, the nozzle blade assembly 8 has a nozzle blade (blade portion) 8a for controlling the flow of the discharged gas, and a nozzle shaft 8b integrally formed with the nozzle blade 8a. That is, in the nozzle blade assembly 8, the nozzle blade 8a is formed at one end of the nozzle shaft 8b. The other end of the nozzle shaft 8b is connected to the other end of the rod plate 3.

[0053] The nozzle shaft 8b of the nozzle blade component 8 can be rotatably inserted into the through hole 2c of the nozzle mounting part 2.

[0054] The rod plate 3 is arranged in the same number as the nozzle blade component 8 along the circumferential direction of the drive ring 5.

[0055] In the following description, the aforementioned components constituting the variable nozzle mechanism 10 will also be referred to as nozzle components P.

[0056] In one embodiment of this configuration, the variable nozzle mechanism 10 is configured such that, by rotating the drive ring 5 around the central axis 10a of the variable nozzle mechanism 10, each rod plate 3 rotates, and the blade angle of the nozzle blade 8a changes.

[0057] When the drive ring 5 rotates around the central axis 10a of the variable nozzle mechanism 10, for example, relative sliding occurs between the outer peripheral surface 8s of the nozzle shaft 8b and the inner peripheral surface 2s of the through hole 2c of the nozzle mounting part 2. For example, relative sliding occurs between the outer peripheral surface 3s of the connecting shaft part 3a provided on one end side of the rod plate 3 and the inner peripheral surface 5s of the groove part 5a of the drive ring 5.

[0058] In a variable-capacity turbocharger 1 with a variable nozzle mechanism 10 configured in one embodiment, the exhaust gas flowing through the vortex-shaped exhaust gas passage 20 is as follows: Figure 1 As indicated by arrow f, the fluid flows between the nozzle mounting portion 2 and the nozzle plate 4, and its flow direction is controlled by the nozzle blades 8a, flowing towards the center of the turbine housing 16. Furthermore, after acting on the turbine rotor 12, it is discharged to the outside from the exhaust outlet 24.

[0059] As described above, in the variable nozzle mechanism 10 of one embodiment, there are wear and other problems due to the presence of sliding parts in the variable capacity turbocharger during operation. Furthermore, iron-based alloys are generally cheaper than heat-resistant nickel-based alloys; therefore, from the viewpoint of controlling manufacturing costs, it is preferable to use more iron-based alloys than heat-resistant nickel-based alloys in the variable nozzle mechanism. However, in the case of using a variable capacity turbocharger in a gasoline engine where the exhaust gas temperature tends to be higher than that of a diesel engine, from the viewpoint of wear resistance and prevention of sequestration under high-temperature environments, it is often necessary to use more expensive heat-resistant nickel-based alloys than iron-based alloys. However, it is desirable to construct the nozzle component using a relatively inexpensive material, namely an iron-based alloy.

[0060] For example, in iron-based alloys, carbon or nitrogen can be added to improve hardness and wear resistance. However, while carbon and nitrogen increase the hardness of the material, they are lightweight elements and therefore readily diffuse in high-temperature environments, such as those above 700 degrees Celsius, exposed to the nozzle components of variable-displacement turbochargers. Therefore, there are cases where the desired increase in hardness cannot be achieved even with the addition of carbon or nitrogen to iron-based alloys. Furthermore, the addition of carbon or nitrogen can lead to excessive hardness and brittleness due to its combination with other elements in the iron-based alloy. Therefore, it is desirable to improve the wear resistance of iron-based alloys at high temperatures without relying on carbon or nitrogen.

[0061] Therefore, wear resistance at high temperatures can be improved by adding not only carbon and nitrogen, but also molybdenum and tungsten to iron-based alloys. Molybdenum and tungsten do not readily combine with other elements in iron-based alloys like carbon or nitrogen, and are therefore stable and less prone to diffusion even at high temperatures compared to carbon or nitrogen.

[0062] The inventors conducted in-depth research and determined that, in the case where the nozzle component P of the variable nozzle mechanism 10 in one embodiment is made of an iron-based alloy, by setting the composition to satisfy the following conditions, the wear resistance of the nozzle component P under high temperature environment can be ensured.

[0063] Specifically, if we define the combined carbon and nitrogen content in the iron-based alloy as A (mass%), and the combined tungsten content (0.5 times) and molybdenum content as B (mass%),

[0064] Satisfy the following equation (1):

[0065] 6.6×A+B≥8.0……(1)

[0066] The relationship expressed can be used to obtain an iron-based alloy with excellent wear resistance in high-temperature environments by setting the total value B to 1.5% or more by mass.

[0067] Therefore, by constructing nozzle component P from such an iron-based alloy, wear resistance under high-temperature environments can be improved.

[0068] Figures 4A to 4D It is a graph showing the results of wear resistance tests on iron-based alloys under high-temperature conditions. Figure 5 This table presents the results of wear resistance tests on iron-based alloys under high-temperature conditions. It should be noted that... Figure 4A In, it means Figure 5 The results of test pieces No. 1-1 to 1-9 in the study. Figure 4B In, it means Figure 5 The results of test pieces No. 2-1 to 2-2. Figure 4C In, it means Figure 5 The results of test pieces No. 3-1 to 3-5. Figure 4D In, it means Figure 5 Results of test pieces No. 4-1 to 4-5.

[0069] exist Figure 5 In the test results shown, the specific wear amount is a relative value when the wear amount of test piece No.4-3 is set to 1.

[0070] exist Figures 4A to 4D middle, Figure 5 The specific wear values ​​shown in the test results are represented by a circular graph. The area of ​​this graph is proportional to the square root of the specific wear value.

[0071] Figures 4A to 4D The curve L in the graph represents the case where the inequality sign in the relation expressed in equation (1) above is replaced with an equality sign. Figures 4A to 4D In the graph, the curve and the region to the right of the curve are the regions that satisfy the relation expressed in equation (1) above.

[0072] Figure 5 The wear resistance test shown in the results was conducted using a ring-on-disk method. Figure 5 One of the material combinations shown is used as a ring-shaped test piece, and the other is used as a disc-shaped test piece. With the disc-shaped test piece and the ring-shaped test piece in contact, the temperature near the contact surface of the ring-shaped test piece is heated to the test temperature. Then, the test load is used to press the ring-shaped test piece onto the disc-shaped test piece, and the disc-shaped test piece is rotated in one direction at the test speed.

[0073] The test conditions for each test piece are as follows.

[0074] For test pieces No.1-1 to 1-9, the material is a certain iron-based alloy (let's call it iron-based alloy X), the test load is 264 (N), the rotation speed is 4.1 (rpm), and the test temperature is 780 (℃).

[0075] For test pieces No. 2-1 and 2-2, the material is an iron-based alloy (let's call it iron-based alloy Y) with a different composition from iron-based alloy X. The test load is 88 (N), the rotation speed is 27.3 (rpm), and the test temperature is 850 (°C).

[0076] For test pieces No. 3-1 to 3-5, the material is a certain nickel-based alloy (let's call it nickel-based alloy X), the test load is 264 (N), the rotation speed is 4.1 (rpm), and the test temperature is 780 (℃).

[0077] For test pieces No. 4-1 to 4-5, the material is a nickel-based alloy with a different composition than nickel-based alloy X (let's call it nickel-based alloy Y), the test load is 88 (N), the rotation speed is 27.3 (rpm), and the test temperature is 850 (°C).

[0078] It should be noted that the wear amount (specific wear amount) of each test piece varies depending on the material and other test conditions. Figures 4A to 4D In the middle, Figure 5 The test results shown are presented separately according to each test condition.

[0079] from Figures 4A to 4D It can be seen that the test piece that does not satisfy the relationship expressed in the above formula (1), that is, the total value A and the total value B exist in the region to the left of the curve line L, has a greater specific wear than the test piece that exists in the region to the right of the curve line L.

[0080] (Regarding the role of each element)

[0081] The role of each element in iron-based alloys will be explained below.

[0082] (Carbon C)

[0083] Carbon in iron-based alloys can enhance their strength through solid solution, changes in phase transformation points, and the formation of compounds.

[0084] (Nitrogen N)

[0085] In addition to having the same effects as carbon, nitrogen can also improve the corrosion resistance of iron-based alloys depending on the conditions, but compared to carbon, it requires additional steps when added.

[0086] (Molybdenum)

[0087] Molybdenum enhances the strength of iron-based alloys through the formation of carbides. In addition, it produces oxides at high temperatures, which contribute to improved wear resistance.

[0088] (Tungsten W)

[0089] Tungsten has the same effect as molybdenum.

[0090] (Chromium Cr)

[0091] Chromium improves the corrosion resistance of iron-based alloys by forming a passive state through oxidation.

[0092] (Ni)

[0093] Nickel can improve the viscosity and strength of iron-based alloys. Additionally, nickel can improve the corrosion resistance and heat resistance of iron-based alloys.

[0094] (Copper Cu)

[0095] Copper can improve the corrosion resistance of iron-based alloys. Additionally, it improves the stamping properties of iron-based alloys by making work hardening less likely. It should be noted that the decrease in hardness of copper at high temperatures is a major reason for the reduced wear resistance of iron-based alloys.

[0096] It should be noted that the nozzle component P in several embodiments may also contain elements such as sulfur (S), manganese (Mn), niobium (Nb), and silicon (Si). Additionally, the nozzle component P in several embodiments may also contain so-called unavoidable impurities.

[0097] (Regarding the upper limit of molybdenum content and total value B)

[0098] As mentioned above, molybdenum and tungsten improve the strength and wear resistance of iron-based alloys. However, excessive addition of molybdenum or tungsten can make the nozzle component P too hard and brittle. Since molybdenum and tungsten are relatively expensive metallic elements, it is desirable to limit their addition from a manufacturing cost perspective.

[0099] The inventors conducted in-depth research and determined that embrittlement can be suppressed by keeping the molybdenum content below 5.0% by mass. Furthermore, they determined that embrittlement can be suppressed by keeping the total value (B) of 0.5 times the tungsten content and the molybdenum content below 6.0% by mass.

[0100] Therefore, in the nozzle component P of several embodiments, the molybdenum content can be 5.0% by mass or less. Furthermore, in the nozzle component P of several embodiments, the total value B of 0.5 times the tungsten content and the molybdenum content can be 6.0% by mass or less. This suppresses embrittlement of the nozzle component P.

[0101] Furthermore, the inventors conducted in-depth research and determined that by suppressing the excessive addition of molybdenum, the wear resistance of iron-based alloys in the mid-temperature region around 400°C can be improved. Therefore, from the viewpoint of ensuring the wear resistance of nozzle component P in the mid-temperature region around 400°C, the molybdenum content can be kept below 2.5% by mass.

[0102] (Regarding the amount of copper added)

[0103] As mentioned above, copper has the effect of improving the corrosion resistance and stamping properties of iron-based alloys.

[0104] However, excessive addition of copper to iron-based alloys leads to a decrease in wear resistance primarily due to reduced high-temperature hardness. Therefore, to achieve high-temperature wear resistance, it is preferable that the copper content in the nozzle component P is 0.0% by mass or more and less than 3.0% by mass.

[0105] Therefore, it is possible to suppress the decrease in wear resistance of nozzle component P under high temperature environment.

[0106] (Regarding the amount of carbon added)

[0107] As mentioned above, carbon can increase the hardness of iron-based alloys through solid solution or compound formation, and increased hardness can also lead to improved wear resistance. However, in materials such as stainless steel where corrosion resistance is ensured by chromium, carbon forms chromium carbide at high temperatures, reducing the concentration of metallic chromium in the material and thus decreasing corrosion resistance. Therefore, it is undesirable to improve wear resistance solely by adding carbon in materials used in high-temperature environments.

[0108] Therefore, in the nozzle component P of several embodiments, the carbon content in the nozzle component P can be more than 0.0% by mass and less than 2.0% by mass.

[0109] As described above, by ensuring that the composition of the iron-based alloy satisfies the relationship expressed in the above formula (1), and that the total value B is 1.5% by mass or more, ensuring the addition of molybdenum and tungsten, and ensuring that the carbon content is 0.0% by mass or more and 2.0% by mass or less, it is possible to suppress the reduction of corrosion resistance as described above and improve the wear resistance of the nozzle component P in high-temperature environments.

[0110] It should be noted that in the nozzle component P of several embodiments, it is not necessary to configure it so that the relationship expressed in the above formula (1) is satisfied in the entire region of the nozzle component P, and the total value B is 1.5% by mass or more. For example, it is also possible to configure the nozzle component P so that the relationship expressed in the above formula (1) is satisfied at least in the vicinity of the surface of the region where relative sliding occurs between it and other components, and the total value B is 1.5% by mass or more.

[0111] That is, the nozzle component P in several embodiments may also include a first region R1 and a second region R2. Here, the first region R1 is the region covering at least a portion of the surface S of the nozzle component P, between the surface S and a position at a depth of 20 μm to 150 μm from the surface S, and is a region that satisfies the relationship expressed in the above formula (1) and has a total value B of 1.5% by mass or more. The second region R2 is a region that differs from the first region R1 in both the position and composition of the nozzle component P.

[0112] As an example, if the nozzle component P is the nozzle mounting part 2, the first region R1 can be the region between the inner circumferential surface 2s of the through hole 2c and a position with a depth of 20 μm to 150 μm from the inner circumferential surface 2s. Furthermore, the second region can, for example, include a region with a depth exceeding 150 μm from the inner circumferential surface 2s.

[0113] For example, in a nozzle component P made of an iron-based alloy, even if the total value B is 1.5% by mass or more, but the carbon and nitrogen content is too low to satisfy the relationship expressed in equation (1) above, it is possible to increase the carbon or nitrogen content in the region near the surface of the nozzle component P by performing carburizing or nitriding treatment, or a combination of carburizing and nitriding treatment, so that the composition of this region satisfies the relationship expressed in equation (1) above. This ensures the wear resistance of this region, i.e., the first region R1, under high-temperature conditions.

[0114] It should be noted that if the thickness of the first region R1 is less than 20 μm, then, for example, if a foreign object collides with the nozzle component P and damages the surface of the nozzle component P, the region lower than the first region R1 (the second region R2) may be exposed. Therefore, the thickness of the first region R1 is preferably 20 μm or more. Furthermore, from the perspectives of wear resistance and surface damage to the nozzle component P as described above, a thicker first region R1 is better. However, if the thickness of the first region R1 increases, the processing costs (amount and time) for carburizing and nitriding processes increase. Therefore, the thickness of the first region R1 can be 150 μm or less.

[0115] This improves the wear resistance of nozzle components in high-temperature environments.

[0116] For example, as described above, in several embodiments, the nozzle component P may be the nozzle mounting portion 2.

[0117] In the variable nozzle mechanism 10 of the variable capacity turbocharger 1 in one embodiment, the nozzle shaft 8b of the nozzle blade component 8 is rotatably inserted into the through hole 2c of the through nozzle mounting part 2. During the operation of the variable capacity turbocharger 1, the outer peripheral surface 8s of the nozzle shaft 8b and the inner peripheral surface 2s of the through hole 2c slide.

[0118] If the nozzle component P in several embodiments is the nozzle mounting part 2, that is, if the nozzle mounting part 2 is made of an iron-based alloy having the above composition, the wear resistance of the through hole 2c of the nozzle mounting part 2 in a high-temperature environment can be improved, and thus the reduction in the control accuracy of the blade angle of the nozzle blade 8a can be suppressed.

[0119] One embodiment of the variable-capacity turbocharger 1 includes a variable nozzle mechanism 10 comprising a first component P1 and a second component P2 capable of sliding with the first component P1. The first component P1 is a nozzle component P made of an iron-based alloy having the composition described above.

[0120] This improves the wear resistance of the first component in high-temperature environments.

[0121] Here, the first component P1 and the second component P2 are components that slide against each other.

[0122] As described above, for example, relative sliding occurs between the outer peripheral surface 8s of the nozzle shaft 8b and the inner peripheral surface 2s of the through hole 2c of the nozzle mounting portion 2. Therefore, in one embodiment of the variable nozzle mechanism 10, for example, if the first component P1 is the nozzle mounting portion 2, then the second component P2 can also be the nozzle blade component 8. Conversely, for example, if the first component P1 is the nozzle blade component 8, then the second component P2 can also be the nozzle mounting portion 2.

[0123] Furthermore, as described above, for example, relative sliding occurs between the outer peripheral surface 3s of the connecting shaft portion 3a provided at one end of the rod plate 3 and the inner peripheral surface 5s of the groove portion 5a of the drive ring 5. Therefore, in the variable nozzle mechanism 10 of one embodiment, for example, if the first component P1 is the rod plate 3, then the second component P2 can also be the drive ring 5. Conversely, for example, if the first component P1 is the drive ring 5, then the second component P2 can also be the rod plate 3.

[0124] It should be noted that the second component P2 can also be made of an iron-based alloy. Moreover, the composition of the second component P2 can also satisfy the relationship expressed in the above formula (1), and the total value B is 1.5% by mass or more.

[0125] Alternatively, the second component P2 can also be made of a nickel-based alloy.

[0126] This improves the wear resistance of the second component P2 in high-temperature environments.

[0127] It should be noted that by making the second component P2 from an iron-based alloy, the manufacturing cost of the second component P2 can be reduced compared to the case where the second component P2 is made from a heat-resistant alloy such as a nickel-based alloy.

[0128] Furthermore, even if the second component P2 is made of a nickel-based alloy, if the first component P1 is made of an iron-based alloy, the manufacturing cost of the first component P1 can be suppressed compared to the case where the first component P1 is also made of a heat-resistant alloy such as a nickel-based alloy.

[0129] One embodiment of the variable capacity turbocharger 1 includes a variable nozzle mechanism 10, thereby improving the durability of the variable capacity turbocharger 1.

[0130] (Manufacturing method of nozzle components)

[0131] The manufacturing method of the nozzle component P in several embodiments will be described.

[0132] Figure 6A This is a flowchart illustrating the manufacturing of nozzle component P in several embodiments via casting.

[0133] Figure 6B This is a flowchart illustrating several embodiments of the nozzle component P manufactured from sheet metal such as rolled material.

[0134] like Figure 6A As shown, a method for manufacturing a nozzle component P according to one embodiment includes a casting step S10A, which forms the nozzle component P by casting an iron-based alloy having the composition of the above-described embodiments.

[0135] It should be noted that, in one embodiment of the manufacturing method of nozzle part P, there may also be a finishing process S20 in which the casting (nozzle part P) obtained in the casting process S10A is finished by cutting or the like.

[0136] Furthermore, as described above, when carburizing or nitriding is required, the casting (nozzle component P) obtained in casting process S10A or the casting (nozzle component P) after finishing process S20 may also be subjected to carburizing or nitriding. That is, the manufacturing method of nozzle component P in one embodiment may also include a surface modification process S30 that performs surface modification treatments such as carburizing or nitriding on the casting (nozzle component P) obtained in casting process S10A or the casting (nozzle component P) after finishing process S20.

[0137] like Figure 6BAs shown, another embodiment of the nozzle component P manufacturing method includes a sheet metal processing step S10B, in which the nozzle component P is formed from a sheet metal such as a rolled material made of an iron-based alloy having the composition of the above-described embodiments.

[0138] It should be noted that, for the manufacturing method of nozzle part P in another embodiment, a surface modification treatment step S30 may also be included, in which the nozzle part P obtained in the sheet metal processing step S10B is subjected to surface modification treatments such as carburizing or nitriding.

[0139] Thus, the method for manufacturing the nozzle component P in several embodiments is a method for manufacturing the nozzle component P included in the variable nozzle mechanism 10 of the variable capacity turbocharger 1, which includes a casting process S10A or a sheet metal processing process S10B as a process of forming the nozzle component P by casting or processing sheet metal.

[0140] Therefore, compared to, for example, forming a nozzle component P using a sintered alloy formed by molding and sintering metal powder, the manufacturing cost of the nozzle component P can be suppressed. Furthermore, compared to, for example, forming a nozzle component P using a sintered alloy, if the nozzle component P is formed by casting or processing sheet metal (rolled material), the microstructure of the nozzle component P is more likely to be dense, thus ensuring the strength and durability of the nozzle component P.

[0141] It should be noted that whether the nozzle component P is a casting can be determined, for example, by observing the microstructure of the cross-section of the nozzle component P to determine if dendritic structures are present. That is, if dendritic structures are confirmed by observing the cross-sectional microstructure of the nozzle component P, then the nozzle component is a casting.

[0142] In addition, whether the nozzle component P is formed from sheet material such as rolled material can be inferred, for example, by observing the morphology of the structure and porosity, and the morphology of the pores when examining the cross-sectional structure of the nozzle component P.

[0143] This disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0144] The contents described in the above embodiments can be understood, for example, as follows.

[0145] (1) In at least one embodiment of this disclosure, the nozzle component P is the nozzle component P included in the variable nozzle mechanism 10 of the variable capacity turbocharger 1. The nozzle component P is made of an iron-based alloy. When the total carbon and nitrogen content of the nozzle component P is set as A (mass %), and the total tungsten content of 0.5 times and molybdenum content is set as B (mass %),

[0146] Satisfy the following formula:

[0147] 6.6 × A + B ≥ 8.0

[0148] The relational expression represented.

[0149] The total value of B is 1.5% by mass or more.

[0150] Based on the structure described in (1) above, the wear resistance of the nozzle component P under high temperature conditions can be improved.

[0151] (2) In several embodiments, in the structure of (1) above, the molybdenum content may be less than 5.0% by mass.

[0152] Based on the structure described in (2) above, the embrittlement of the nozzle component P can be suppressed.

[0153] (3) In several embodiments, according to the structure of (1) or (2) above, the copper content in the nozzle component P can be more than 0.0% by mass and less than 3.0% by mass.

[0154] Based on the structure described in (3) above, the wear resistance of the nozzle component P can be suppressed under high temperature conditions.

[0155] (4) In several embodiments, according to any of the structures described in (1) to (3) above, the carbon content in the nozzle component P can be more than 0.0% by mass and less than 2.0% by mass.

[0156] According to the structure in (4) above, by making the composition of the iron-based alloy satisfy the above relationship and making the total value B more than 1.5% by mass, and on this basis, making the carbon content more than 0.0% by mass and less than 2.0% by mass, it is possible to suppress the reduction of corrosion resistance and improve the wear resistance of the nozzle component P in high temperature environment.

[0157] (5) In several embodiments, according to any of the structures described in (1) to (4) above, the nozzle component P may include a first region R1 and a second region R2. Here, the first region R1 is a region covering at least a portion of the surface S of the nozzle component P, between the surface S and a position at a depth of 20 μm to 150 μm from the surface S, and is a region that satisfies the above relationship and whose total value B is 1.5% by mass or more. The second region R2 is a region of the nozzle component P whose position and composition differ from the first region R1.

[0158] Based on the structure described in (5) above, the wear resistance of the nozzle component P in high-temperature environments can also be improved.

[0159] (6) In several embodiments, according to any of the structures described in (1) to (5) above, the nozzle component P may be the nozzle mounting portion 2.

[0160] According to the structure described above (6), since the wear resistance of the through hole 2c of the nozzle mounting part 2 can be improved under high temperature environment, the reduction in the control accuracy of the blade angle of the nozzle blade 8a can be suppressed.

[0161] (7) The variable nozzle mechanism 10 of the variable capacity turbocharger 1 of at least one embodiment of the present disclosure includes a first component P1 and a second component P2 that can slide with the first component P1. The first component P1 is a nozzle component P of any of the structures described in (1) to (6) above.

[0162] Based on the structure described in (7), the wear resistance of the first component P1 under high temperature conditions can be improved.

[0163] (8) In several embodiments, according to the structure described in (7) above, the second component P2 may also be made of an iron-based alloy. Moreover, the composition of the second component P2 can satisfy the above relationship, and the total value B is 1.5% by mass or more.

[0164] Based on the structure described in (8), the wear resistance of the second component P2 in high-temperature environments can also be improved.

[0165] (9) In several embodiments, according to the structure of (7) above, the second component P2 may also be made of a nickel-based alloy.

[0166] Based on the structure described above (9), the wear resistance of the second component P2 in high-temperature environments can also be improved.

[0167] (10) The variable capacity turbocharger 1 of at least one embodiment of the present disclosure has a variable nozzle mechanism 10 with any of the structures described in (7) to (9) above.

[0168] Based on the structure described above (10), the durability of the variable capacity turbocharger 1 can be improved.

[0169] (11) The method of manufacturing the nozzle component of at least one embodiment of the present disclosure is a method of manufacturing the nozzle component P included in the variable nozzle mechanism 10 of the variable capacity turbocharger 1, which includes a step of forming the nozzle component P of claim 1 by casting or processing a sheet metal (casting step S10A or sheet metal processing step S10B).

[0170] According to the method described in (11) above, compared to the case where the nozzle component P is formed by, for example, sintering metal powder into a sintered alloy, the manufacturing cost of the nozzle component P can be suppressed. Furthermore, according to the method described in (11) above, compared to the case where the nozzle component P is formed by, for example, sintering a sintered alloy, if the nozzle component P is formed by casting or processing sheet metal (rolled material), the microstructure of the nozzle component P is more likely to be dense, thus ensuring the strength and durability of the nozzle component P.

[0171] Explanation of reference numerals in the attached figures

[0172] 1. Variable capacity turbocharger

[0173] 2 Nozzle mounting section

[0174] 3-pole board

[0175] 5 drive rings

[0176] 8-nozzle blade assembly

[0177] 10 Variable Nozzle Mechanism

[0178] P nozzle component

[0179] P1 First Component

[0180] P2 Second Component

[0181] R1 First Area

[0182] R2 Second Region

Claims

1. A nozzle member that is a nozzle member included in a variable nozzle mechanism of a variable capacity type turbocharger, the nozzle member characterized in that, the nozzle member is composed of an iron-based alloy, an addition value of a carbon content and a nitrogen content is set as A mass%, an addition value of 0.5 times a tungsten content and a molybdenum content is set as B mass% in a case where, the following expression is satisfied: 6.6 x A + B ≥ 8.0 the relational expression, a value of the addition value B is 1.5 or more, the nozzle member includes: a first region that is a region of at least a portion of a surface of the nozzle member, the surface and a region between a position of a depth of 20 μm or more and 150 μm or less from the surface satisfies the relational expression and the value of the addition value B is 1.5 or more; a second region that is a region of a position and a composition of the nozzle member that is different from the first region.

2. The nozzle member according to claim 1, wherein, the molybdenum content is 5.0 mass% or less.

3. The nozzle member according to claim 1, wherein, a copper content in the nozzle member is 0.0 mass% or more and less than 3.0 mass%.

4. The nozzle member according to claim 1, wherein, a carbon content in the nozzle member is 0.0 mass% or more and 2.0 mass% or less.

5. The nozzle member according to claim 1, wherein, the nozzle member is a nozzle mounting portion.

6. A variable nozzle mechanism of a variable capacity type turbocharger characterized by comprising: provided with: a first member; a second member that is slidable with the first member; the first member is the nozzle member according to claim 1.

7. The variable nozzle mechanism of a variable capacity type turbocharger according to claim 6, wherein, the second member is composed of an iron-based alloy, the relational expression is satisfied and the value of the addition value B is 1.5 or more.

8. The variable nozzle mechanism of a variable capacity type turbocharger according to claim 6, wherein, the second member is composed of a nickel-based alloy.

9. A variable capacity type turbocharger characterized in that, the variable nozzle mechanism according to claim 6 is provided.

10. A nozzle member manufacturing method that is a nozzle member manufacturing method of a nozzle member included in a variable nozzle mechanism of a variable capacity type turbocharger, the nozzle member manufacturing method characterized in that, a process of forming the nozzle member according to claim 1 or 2 by casting or by processing a sheet material is provided.

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