JP2002332862A - Exhaust emission guide assembly of vgs turbocharger constituted of high chromium and high nickel material, and having improved durability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission guide assembly of a novel VGS turbocharger, capable of increasing the high-temperature wear resistance, oxidation resistance, and hot hardness. SOLUTION: The component members of the exhaust emission guide assembly A, such as a variable vane 1, a turbine frame 2, and a variable mechanism 3 are formed mainly of a high chromium and high nickel heat resistant metals added with 0.2 to 0.5% C, 15 to 30% Cr, 15 to 30% Ni, 0.01 to 0.1% Pb, 0.01 to 0.1% Se, 0.01 to 0.1% Te, 0.02 to 0.1% O, and 0.005 to 0.05% S (for all the elements the units are wt.%) to increase the durability.

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, when the engine is running at a low speed, the exhaust gas flow decreases and the exhaust turbine feels sluggish until it runs efficiently, and the time required until it blows up at once, so-called turbo lag, etc. Was inevitable. 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]

[Technical Problems Attempted to Be Developed] The present invention has been made in view of such a background, and is useful as a material for forming an exhaust guide assembly, which has excellent heat resistance, precision casting or metal injection molding. This is an attempt to develop a material to which the method can be applied.

[0005]

According to a first aspect of the present invention, there is provided an exhaust guide assembly of a VGS type turbocharger comprising a high chromium and a high nickel material according to claim 1 and having improved durability. A variable blade for appropriately adjusting and rotating the exhaust turbine, a turbine frame for rotatably supporting the variable blade on the outer peripheral portion of the exhaust turbine, and a variable blade for adjusting the flow rate of the exhaust gas by appropriately rotating the variable blade. The exhaust guide assembly of a VGS type turbocharger having a mechanism, a small exhaust flow rate is narrowed down by the variable blades, the exhaust speed is increased, and high output can be exhibited even at low speed rotation. The heat-resistant member is configured to combine a predetermined weight% of carbon and a predetermined weight% of another alloy element group with respect to iron. A chromatic are not formed by the alloy, the weight percent of carbon and other alloying elements group, C 0.2 to 0.5%,
Cr is 15 to 30%, Ni is 15 to 30%, and Pb is 0.1 to 30%.
01-0.1%, Se 0.01-0.1%, Te 0.01-0.1%, O 0.02-0.1%, S 0.005-0.05% It is characterized in that each is set so that According to the present invention, a variable wing (VGS) control unit having excellent heat resistance can be manufactured by a precision casting method and a metal injection molding method.

Here, the precision casting method is a casting method for castings requiring high dimensional accuracy, and includes a lost wax method, a shell molding method, an investment casting method,
There are the ADIC method and the like, and among them, the lost wax casting method is useful as a method for producing a casting having the most complicated shape with the highest accuracy. Metal injection molding (MIM) is a method in which metal powder is kneaded with a suitable binder, plasticized, injected into a mold, solidified, then the binder is removed, and sintering is performed. The feature is that products with complex shapes can be mass-produced.

[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 base material of the present invention is basically manufactured by an ordinary precision casting method or metal injection molding method (see later). Post 1,
2). After the composition is controlled by converter refining and the composition is further refined by out-of-pile refining, the slab is formed by a continuous casting machine. After that, slab heating at 1200 ° C or more and soaking for 1 hour or more is performed, hot rolling such as a Steckel mill under initial light pressure is performed, and hot rolling is performed while operating the rolling lower limit temperature at 950 ° C or more. Quench by cooling water injection. The hot-rolled coil thus obtained is cold-rolled, and annealing (annealing) is performed at about 1100 ° C. in a continuous facility to avoid carbide formation of the base iron to obtain a product material. The reasons for limiting each component of the alloy cast steel are shown below. 0.2 for C
The content of 0.5% to 0.5% is intended to improve the fluidity, high-temperature strength, and coatability, and the content of 15% to 30% of Cr is for the purpose of improving heat resistance. The Ni content of 15 to 30% is intended to improve particularly high-temperature strength, high-temperature oxidation resistance, thermal fatigue, and thermal expansion (dimensional change). Pb is 0.01 to 0.1
The percentages are used to facilitate the machinability of precision casting, MIM near net shape parts, and to improve MIM sinterability. Se is set to 0.01 to 0.1% in order to facilitate precision casting, machinability of MIM near net shape parts, and to improve MIM sinterability. The reason why the content of Te is set to 0.01% to 0.1% is to facilitate precision casting, mechanical machinability of MIM near net shape parts, and to improve MIM sinterability. O is set to 0.02 to 0.1% in order to improve the flowability of the molten metal during precision casting. S is set to 0.005 to 0.05% in order to improve the flowability of the molten metal during precision casting.

(2) Manufacture of exhaust guide assembly (A) Precision casting method Manufacture Manufacture was performed in consideration of the above component combination by a lost wax casting method representing a precision casting method. In this method, a refractory coating phase is formed around a wax model prototype having the same shape as the product to be cast, and then the whole is heated to melt only the wax model. Specifically, it is manufactured in the following process, and measures are taken to increase the degree of near net shape. The components are adjusted using an Fe-Ni-Cr-based master alloy in an electric furnace, the viscosity of the melt is reduced by high-temperature smelting, and quenched casting is performed to the extent that thermal stress cracking does not occur in this refractory mold. Minimize tolerances, ie, increase dimensional accuracy. Then, after cooling, the mold is separated, and the runner is cut, pickled and washed to obtain a near net product.
And it becomes an assembly part through a light cutting process. The present invention incorporates new knowledge for minimizing the load on the subsequent steps such as cutting and polishing.

2. Manufacturing data Table 1 below shows comparison data with conventional products.

[0019]

[Table 1]

(B) Metal injection molding method Manufacture Removes surface oxides in a reducing atmosphere as a fine raw material powder to increase air / water atomization release speed and cooling speed and control nozzle shape and size, and sinters just below the melting point (about -20 ° C) to produce independent bubbles. And injection molding to produce a near net product. Then, through a light cutting process, it is made into an assembly part.

2. Data on products Table 2 below shows comparison data with conventional products.

[0022]

[Table 2]

(3) Durability The above-mentioned lost wax casting or MIM cut product is subjected to a salt bath treatment (a carburizing treatment as necessary) to form a carbide film to form an assembly member. Table 3 below shows the data for improving the durability.

[0024]

[Table 3]

[0025]

According to the present invention, by using a novel alloy, the precision casting method has high dimensional accuracy,
In addition to a small variation, it is possible to manufacture the exhaust guide assembly component having a small solidified grain and easy rolling, and in the metal injection molding method, the bulk density is high and the high-temperature rotary bending fatigue property is high. The invention can be applied to a mass-productive manufacturing method, for example, it is possible to manufacture exhaust guide assembly components. That is, it is possible to improve the productivity of the exhaust guide assembly which is excellent in heat resistance and high in quality.

[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) F02B 37/24 F02B 37/12 301Q

Claims (1)

[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 exhaust gas flow rate by rotating the wings appropriately. The variable exhaust blade narrows down a small exhaust flow rate, increases the exhaust speed, and can exhibit high output even at low speed rotation. An exhaust guide assembly for a turbocharger, wherein the heat-resistant member constituting the exhaust guide assembly is an alloy containing a predetermined weight% of carbon and a predetermined weight% of another alloy element group with respect to iron, And 0.2% to 0.5% of C, 15% to 30% of Cr, and 1% of Ni
5 to 30%, Pb is 0.01 to 0.1%, Se is 0.0
1-0.1%, Te 0.01-0.1%, O 0.0
A VGS type turbocharger made of high chromium and high nickel material and having improved durability characterized by being set to be 2 to 0.1% and S to be 0.005 to 0.05%, respectively. Exhaust guide assembly.