JP2002332860A - Exhaust guide assembly for vgs turbocharger with improved durability composed of heat resisting member with increased carbon solid solubility at high temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust guide assembly for a new VGS turbocharger, having improved high-temperature wear resistance, oxidation resistance, and hot hardness, or the like. SOLUTION: Durability is improved, by constituting a constituent member of the exhaust guide assembly A, such as a variable blade 1, a turbine frame 2, or a varying mechanism 3 by a heat resisting member using heat resistant metal as a main matrix and containing 0.2-0.5%C, 5-10%Mn, 10-20%Ni, 15-25%Cr, 0.05-0.2%N and 0.01-0.1% of one or two types from La, Ce, and Sm (units for all the elements are wt.%), and forming a coat of chromium carbide on the surface of the member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger used for an automobile engine and the like.
In particular, the present invention relates to an exhaust guide assembly incorporated therein.

[0002]

2. Description of the Related Art A turbocharger is known as a supercharger used as a means for increasing the output and performance of an automobile engine. This turbocharger drives a turbine by the exhaust energy of the engine. This is a device that rotates the compressor by the output to bring the engine to a supercharged state that is higher than natural intake. By the way, this turbocharger has a problem that when the engine is running at a low speed, there is a feeling of sluggishness until the exhaust turbine rotates efficiently due to a decrease in the exhaust flow rate, and a so-called turbo lag or the like, which is a necessary time until the exhaust is blown all at once. It was unavoidable. Also, a diesel engine having a low engine speed originally had a disadvantage that it was difficult to obtain a turbo effect.

For this reason, a VGS type turbocharger which operates efficiently even in a low speed rotation range has been developed. This engine is capable of exhibiting high output even at low rotation speeds by narrowing a small amount of exhaust with variable blades (blades), increasing the exhaust speed, and increasing the work of the exhaust turbine. In a diesel engine in which the amount of NOx in the exhaust gas is a problem, the turbocharger is a useful turbocharger that can improve the efficiency of the engine from a low speed rotation. The exhaust guide assembly in this VGS type turbocharger is used under a high temperature and exhaust gas atmosphere.
Materials with heat resistance, such as JIS, SUS, SU
Although heat-resistant materials such as H, SCH, and NCF superalloys are used, since they are used under extremely severe conditions,
The durable life has a certain limit, and further improvement in durability is desired.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and is directed to a heat cycle involving a high temperature of 700 ° C. or more, an exhaust guide used for a long time in an exhaust gas atmosphere. An attempt was made to improve the high-temperature wear resistance, oxidation resistance, high-temperature strength, hardness, and the like of the members constituting the assembly.

[0005]

According to the first aspect of the present invention, there is provided an exhaust guide assembly of a VGS type turbocharger comprising a heat resistant member having an increased carbon solid solubility at a high temperature and having improved durability. A variable blade that rotates the exhaust turbine by appropriately adjusting the flow rate of the exhaust gas to be discharged, a turbine frame that rotatably supports the variable blade at the outer peripheral portion of the exhaust turbine, and appropriately rotates the variable blade, An exhaust guide assembly for a VGS type turbocharger that has a variable mechanism that adjusts the exhaust gas flow rate, reduces the exhaust gas flow rate with variable blades, increases the exhaust speed, and can exhibit high output even at low speed rotation. The heat-resistant member of the exhaust guide assembly has a predetermined weight% of carbon and a predetermined weight% of iron. An alloy formed by incorporating an impurity of the other alloying elements group and unavoidable, weight% of carbon and other alloying elements group, C is 0.2 to 0.5%, Mn is 5.0 to
10%, 10-20% Ni, 15-25% Cr, N
Is set to be 0.05 to 0.2%, and one or two of La, Ce, and Sm are set to be 0.01 to 0.1%, respectively. According to the present invention, a carbide film can be formed without performing a carburizing treatment, and the exhaust guide assembly having high durability can be manufactured at low cost. This is because such a composition control of the component realizes a solid solution state of carbon, that is, a state in which carbon can be freely diffused and moved without forming a carbide, and a single phase of carbide can be formed at the time of film formation. Where La, C
One or two of e and Sm are, for example, La of 0.07%, La + Ce of 0.07%, Ce + Sm of 0.07%, or the like, where La is 0.07% or La + Ce is 0.07%. % Is preferred.

According to a second aspect of the present invention, there is provided an exhaust guide assembly of a VGS type turbocharger having improved durability constituted by a heat-resistant member having an increased carbon solid solubility at a high temperature, which constitutes the exhaust guide assembly. Item 1 is characterized in that the surface of the heat-resistant member according to Item 1 is coated with chromium carbide. According to the present invention, the durability of the heat-resistant member can be improved. Here, as the chromium carbide of the coating component, Cr ₂₃ C ₆ , Cr ₇ C
There are _3, Cr ₃ C _2, etc., in particular the film from the viewpoints of high temperature friction
Cr ₇ C ₃ is preferred.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. In the description, the exhaust guide assembly in the VGS type turbocharger according to the present invention will be described, and then the manufacture of a heat-resistant member constituting the exhaust guide assembly A and the manufacture of the exhaust assembly using the heat-resistant member will be described. .

[1] Exhaust Guide Assembly The exhaust guide assembly A adjusts the exhaust gas flow by appropriately restricting the exhaust gas G particularly at the time of low-speed rotation of the engine. As an example, as shown in FIG. A plurality of variable blades 1 provided on the outer periphery of the turbine for substantially setting the exhaust flow rate, a turbine frame 2 for holding the variable blades 1 rotatably, and the variable blades 1 for appropriately setting the flow rate of the exhaust gas G. And a variable mechanism 3 for rotating by a fixed angle.

First, the variable wing 1 will be described. As an example, as shown in FIG. 1, a plurality of (one exhaust guide assembly A) is formed in an arc shape along the outer periphery of the exhaust turbine T.
, And each of them is rotated by approximately the same amount to adjust the exhaust flow rate appropriately. Each variable wing 1 includes a wing 11 and a shaft 12. The wing portion 11 is formed so as to have a constant width mainly in accordance with the width dimension of the exhaust turbine T, and has a substantially wing-shaped cross section in the width direction, so that the exhaust gas G can be effectively discharged from the exhaust turbine T. It is configured to face T. Here, the width of the wing portion 11 is referred to as a blade height h for convenience. The shaft portion 12 is formed so as to be continuous with the wing portion 11 integrally, and serves as a portion corresponding to a rotation axis when the wing portion 11 is moved.

A connecting portion between the wing portion 11 and the shaft portion 12 includes a tapered portion 13 narrowing from the shaft portion 12 toward the wing portion 11 and a flange portion 14 having a diameter somewhat larger than that of the shaft portion 12. Are formed so as to be continuous. The bottom surface of the flange portion 14 is formed on substantially the same plane as the end surface of the blade portion 11 on the shaft portion 12 side.
In this state, a smooth rotation is ensured in a state in which it is attached to the camera. Further, a reference surface 15 which is a reference of the mounted state of the variable wing 1 is formed at the tip of the shaft portion 12. This reference plane 15
Is a portion fixed by caulking or the like to a variable mechanism 3 described later. As an example, as shown in FIG.
2 is formed so that a flat surface which is notched opposite to the wing portion 11 is formed in a substantially constant inclined state with respect to the wing portion 11.

Next, a turbine frame 2 to which the present invention is substantially applied will be described. This is configured as a frame member that rotatably holds a plurality of variable wings 1, and as an example, as shown in FIG. 1, the variable wing 1 is sandwiched between a frame segment 21 and a holding member 22. It is configured as follows. And frame segment 2
1 is a flange portion 23 for receiving the shaft portion 12 of the variable wing 1
And a boss 24 for fitting a variable mechanism 3 to be described later on the outer periphery. It should be noted that the same number of receiving holes 25 as the number of the variable wings 1 are formed at equal intervals in the peripheral portion of the flange portion 23 from such a structure.
5 is formed with high efficiency and finished with high precision. Therefore, the substantial application object of the present invention is the frame segment 21.

Further, as shown in FIG. 1, the holding member 22 is formed in a disk shape with a central portion opened. The dimension between the two members is substantially constant (generally the wing width of the variable wing 1) so that the wing portion 11 of the variable wing 1 sandwiched between the frame segment 21 and the holding member 22 can be always smoothly rotated. For example, the dimensions between the two members are maintained by crimping pins 26 provided at four positions on the outer peripheral portion of the receiving hole 25. Here, a hole opened in the frame segment 21 and the holding member 22 for receiving the caulking pin 26 is referred to as a pin hole 27.

In this embodiment, the flange portion 23 of the frame segment 21 has two flange portions: a flange portion 23A having substantially the same diameter as the holding member 22 and a flange portion 23B having a diameter somewhat larger than the holding member 22. These are formed by the same member,
When processing with the same member becomes complicated, for example, two flange portions having different diameters may be divided and formed, and then joined by caulking or brazing.

Next, the variable mechanism 3 will be described. This is provided on the outer peripheral side of the boss portion 24 of the turbine frame 2 and rotates the variable blade 1 to adjust the exhaust flow rate. As an example, as shown in FIG. The variable wing 1 includes a rotating member 31 that causes the rotation of the variable wing 1 and a transmission member 32 that transmits the rotation to the variable wing 1. The rotating member 31 is formed in a substantially disk shape with a central portion opened as shown in the figure, and the same number of transmitting members 32 as the variable wings 1 are provided at equal intervals on the peripheral edge portion. The transmission member 32 includes a driving element 32A rotatably attached to the rotating member 31, and a variable wing 1
Element 32 fixedly mounted on the reference surface 15 of the
B, and the rotation is transmitted in a state where the driving element 32A and the passive element 32B are connected. Specifically, the square-shaped driving element 32A is rotatably pinned to the rotating member 31, and the substantially U-shaped passive element 32B that can receive the driving element 32A is changed. The wing 1 is fixed to the reference surface 15 at the tip, and the square-shaped drive element 32A is connected to the U-shaped passive element 32.
B, and the rotating member 31
Is attached to the boss 24.

In order to align the plurality of variable wings 1 circumferentially in the initial state in which the plurality of variable wings 1 are attached, it is necessary that each of the variable wings 1 and the passive element 32B be attached at a substantially constant angle. In the embodiment, the reference surface 15 of the variable wing 1 mainly performs this action. Further, if the rotating member 31 is slightly fitted to the boss portion 24, when the rotating member 31 is slightly separated from the turbine frame 2,
Since there is a concern that the engagement of the transmission member 32 may be released, a ring 33 or the like is provided so as to sandwich the rotating member 31 from the opposite side of the turbine frame 2 in order to prevent this.
This imparts a tendency of the rotating member 31 to be pressed toward the turbine frame 2. With such a configuration, when the engine rotates at a low speed, the rotating member 31 of the variable mechanism 3
Is appropriately rotated and transmitted to the shaft portion 12 via the transmission member 32, and the variable wing 1 is rotated as shown in FIG.
Is appropriately reduced to adjust the exhaust flow rate.

[2] Manufacture of exhaust guide assembly (1) Manufacture of heat-resistant member (alloy) The alloy of the present invention is manufactured by a usual method. Note that the two embodied embodiments are as shown in Table 1. The reasons for limiting each component of the alloy are shown below. C
Is 0.2 to 0.5% is an appropriate range for forming a sufficient film by requiring chromium carbide having sufficient high-temperature durability. Mn is set to 5 to 10% in order to maintain the solid solution amount of carbon in an appropriate range of 0.2 to 0.5%. Ni 1
The reason for setting the content to 0 to 20% is that the solid solution amount of carbon is 0.2 to 0.5
% To keep it in the appropriate range. The reason for setting the Cr content to 15 to 25% is to keep the amount of solid solution of carbon in an appropriate range of 0.2 to 0.5%. N is set to 0.05 to 0.2% in order to keep the amount of solid solution of carbon in an appropriate range of 0.2 to 0.5%. La, C
e, one or two of Sm are 0.01 to 0.1%
The reason is that the amount of solid solution of carbon is kept in an appropriate range of 0.2 to 0.5% to contribute to the formation of chromium carbide.

(2) Manufacture of an exhaust guide assembly The composition is controlled by converter refining, the composition is further refined by out-of-pile refining, and then slabs, billets, blooms, etc. are formed by continuous casting. Produce heat-resistant materials by cold rolling and cold rolling. This is used for processing and heat treatment to form an exhaust guide assembly.

(3) High Temperature Strength Table 1 shows data for improving the high temperature strength.

[0019]

[Table 1]

[3] Coating of Exhaust Guide Assembly (1) As a method of coating the surface of the alloy in the present invention, it is preferable to use a salt bath method, and specifically, it is performed in the following steps. After washing the assembly parts, 500 ℃
And then immersed in a salt bath at about 1000 ° C. containing chloride and chromium oxide in borax, followed by neutralization washing. (2) Durability Table 2 below shows data for improving durability.

[0021]

[Table 2]

[0022]

According to the present invention, high durability of a heat-resistant member constituting an exhaust guide assembly in a VGS type turbocharger can be achieved while keeping costs low.

[Brief description of the drawings]

FIG. 1 shows a V incorporating a turbine frame according to the present invention.
FIG. 2A is a perspective view showing a GS type turbocharger, and FIG. 2B is an exploded perspective view showing an exhaust guide assembly.

[Explanation of symbols]

 Reference Signs List 1 variable blade 2 turbine frame 3 variable mechanism 11 blade 12 shaft 13 taper 14 flange 15 reference surface 21 frame segment 22 holding member 23 flange 23A flange (small) 23B flange (large) 24 boss 25 receiving Hole 26 Caulking pin 27 Pin hole 31 Rotating member 32 Transmission member 32A Drive element 32B Passive element 33 Ring A Exhaust guide assembly h Blade height G Exhaust gas T Exhaust turbine

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01D 25/24 F01D 25/24 EM N

Claims (2)

[Claims] A variable blade for rotating an exhaust turbine by appropriately adjusting a flow rate of exhaust gas discharged from an engine; a turbine frame rotatably supporting the variable blade on an outer peripheral portion of the exhaust turbine; The VGS type is equipped with a variable mechanism that adjusts the flow rate of exhaust gas by appropriately rotating the blades. The variable exhaust blades narrow down a small amount of exhaust gas to increase the speed of exhaust and achieve high output even at low speed rotation. In an exhaust guide assembly for a turbocharger, an alloy in which a heat-resistant member constituting the exhaust guide assembly contains a predetermined weight% of carbon, a predetermined weight% of another alloy element group, and unavoidable impurities with respect to iron. Wherein the weight percent of carbon and other alloying elements is 0.2-0.5% C, 5.0-10% Mn, 10-20% Ni, r is 15~25%, N is 0.05
0.2%, one of or two of La, Ce, and Sm are each set to be 0.01 to 0.1%, and the carbon solid solubility at high temperature is increased. Exhaust guide assembly of VGS type turbocharger made of heat resistant material and improved in durability. 2. The heat-resistant member according to claim 1, wherein the surface of the heat-resistant member constituting the exhaust guide assembly is coated with chromium carbide. VGS type turbocharger exhaust guide assembly with improved durability.