JP2003035152A - Turbocharger housing and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbocharger housing and a manufacturing method for the same, that enable an internal exhaust gas flow path to be machined to a smooth surface to close tolerances and enables making a thin-wall, lightweight housing, at a lower cost. SOLUTION: A turbocharger housing 1 is provided with a pair of housing halves (castings) 2, 3, which are welded together at an abutting surface 14 thereof. Each of the housing halves 2, 3 has a built-in, substantially circular flow path R for exhaust gases R and is abutted against each other on the abutting surface 14, that runs in a direction substantially orthogonal in relation to the center axis of the flow path R and substantially along the radial direction of the flow path R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharger housing for rotatably incorporating a turbine in a turbocharger (supercharger) of an automobile and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art For a turbocharger housing, a casting material having an integral structure by a shell molding method or a sheet metal welding assembly material for welding a plurality of sheet metal working materials is used. In the turbocharger housing made of the above-mentioned cast material, as the internal structure becomes complicated due to the twin scroll, it is more likely that casting defects such as shrinkage cavities will occur and the inner peripheral surface forming the scroll will be rough. It is difficult to improve the degree of accuracy, and there is a limit to thinning and weight reduction of the supercharger housing.

Further, in the turbocharger housing made of the above-mentioned sheet metal welded assembly, the internal structure becomes complicated due to the twin scroll, but the press precision of the metal thin plate has a limit in the forming accuracy, and the welded portion is welded. Since there are many distortions and heat-affected zones, there is a problem that the welding quality is not stable. Moreover, it is not practical to solve the problems of the turbocharger housing made of the above-mentioned cast material and the above-mentioned sheet-metal welded assembly because the cost becomes high. For example, there is a vacuum suction casting method in which a mold formed by the lost wax method is attached to a vacuum chamber and the molten metal is sucked into the cavity in the mold, but it is difficult to make the thickness of the housing less than 2 mm. is there.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, makes it possible to form the internal exhaust gas passage with a precise and smooth surface, and to reduce the thickness and cost. An object is to provide a possible turbocharger housing and a method for manufacturing the same.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been conducted as a result of earnest research and investigation by the inventor,
It is based on the idea of dividing the turbocharger housing into a plurality of cast parts and welding them into an integral housing. That is, the turbocharger housing of the present invention (Claim 1) has a substantially circular exhaust gas passage therein, is substantially orthogonal to the central axis of the passage, and is substantially along the radial direction of the passage. It is characterized in that it is composed of a plurality of cast parts that are abutted with each other (butting) surfaces, and that the plurality of cast parts are welded with each other abutting surfaces.

According to this, a plurality of cast parts having no or few hollows are welded at the abutting surfaces, so that the turbocharger housing can be made thin and lightweight. Moreover, exhaust gas flow paths in individual cast parts
Since the surface of (scroll) is smoothed accurately,
It is possible to reduce turbulence of the gas flow and also contribute to increasing the compression efficiency of the intake gas. The plurality of cast parts are formed by a precision casting method such as a vacuum suction casting method using a lost wax mold, but may be cast parts by other casting methods. Further, the welding is preferably laser welding, electron beam welding or the like, which does not require a groove to be formed on the abutting surface and can be welded while the welding bead does not easily reach the inner exhaust gas passage. However, it is not limited to these.

Further, according to the present invention, the exhaust gas flow passage is composed of two flow passages which are substantially parallel to each other, and which are substantially orthogonal to the central axes of the two flow passages and in the radial direction of the two flow passages. Also included is a turbocharger housing (claim 2), which consists of three cast parts abutting at two (butting) faces that are substantially along. According to this, since it is formed of three cast parts, even if it has a complicated shape or structure such as a so-called twin scroll, it is thin and lightweight, and the surface of the flow path of the exhaust gas can be made smooth. The turbocharger housing has excellent dimensional accuracy. Further, the present invention includes
A turbocharger housing in which a casting part located in the middle among the three casting parts has a partition wall projecting along the circumferential direction of the inner surface thereof to partition the two flow paths.
(Claim 3) is also included. According to this, in a so-called twin scroll turbocharger housing in which two exhaust gas flow paths are arranged in parallel and in a spiral shape, it can be made thin and lightweight, and the surface of the scroll is made smooth to achieve high performance. Can be one.

On the other hand, in the method for manufacturing a turbocharger housing of the present invention (claim 4), the exhaust gas passage having a substantially circular shape is built in, and is substantially orthogonal to the central axis of the passage and the above passage is provided. The step of individually casting a plurality of cast parts divided by (butting) surfaces that are substantially along the radial direction of, and the step of welding the obtained plurality of cast parts at the butt surfaces of each other. Characterize. According to this, since a plurality of cast parts with few or no hollows are welded at the abutting surfaces, a turbocharger housing that is thin and lightweight and has a smooth exhaust gas passage (scroll) surface is provided. Therefore, it is possible to reliably provide at low cost.

Further, according to the present invention, the exhaust gas flow passages are composed of two flow passages which are substantially parallel to each other, and are substantially orthogonal to the central axes of the two flow passages, and in the radial direction of the two flow passages. 3 abutting with two (butting) faces that are almost along
Also included is a method of manufacturing a turbocharger housing (Claim 5) including the steps of casting one cast part and welding the resulting three cast parts along the two abutting surfaces. According to this, it is possible to reliably provide a high-performance turbocharger housing having a so-called twin scroll that is thin and lightweight and has a smooth exhaust gas flow path.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a turbocharger housing 1 according to one embodiment of the present invention. As shown in FIG. 1, the turbocharger housing 1 is composed of a pair of left and right housing halves (cast parts) 2 and 3, and is laser-welded W along these abutting surfaces 14. The housing half 2 on the left side is internally provided with a ring-shaped annular portion 4 having a substantially semicircular section and forming a half of the flow path R of the exhaust gas G having a substantially circular shape, and a hollow portion 8 for housing the turbine 15. Stand 1 including a cylindrical portion 6 and a base 12
It has 0 and 1 integrally. Also, the right housing half 3
Is an annular portion 5 having a substantially semicircular cross section and forming a half of the flow path R of the exhaust gas G having a substantially circular shape, and the exhaust gas G that collides with and rotates the turbine 15. A cylindrical portion 7 having a discharge passage 9 therein and a stand 11 including a base 13 are integrally provided.

The housing halves 2 and 3 are made of, for example, ferritic or austenitic stainless steel cast steel (JI
S: SCS1, SCS16), or heat-resistant cast steel (JI
S: SCH13, SCH22) is a precision casting part in which a molten metal composed of S: SCH13, SCH22) is suction-decompressed and cast into a cavity of a lost wax mold (not shown) and has a thickness of 1.2 to 1.8 m.
In the range of m and the average thickness is 1.5 mm. Further, as shown in FIG. 1, the annular portions 4,5 of the housing halves 2,3 are
Forms a half of the flow path R of the exhaust gas G having a substantially circular shape, and the flow path R is opened in a ring shape between the cylindrical portions 6 and 7. A turbine wheel 17 fixed to one end of a shaft 16 supported by a bearing (not shown) is located in the hollow portion 8 of the cylindrical portion 6, and a plurality of blades 18 spirally extending toward the discharge passage 9 are provided at the tip end side thereof. Is projected.

Further, as shown in FIG. 1, in the radial direction of the flow passage R, which is orthogonal to the central axis of the flow passage R of the exhaust gas formed by the annular portions 4 and 5 of the housing halves 2 and 3. The turbocharger housing 1 is formed by welding the annular portions 4 and 5 and the stands 10 and 11 by laser welding W along the abutting surface 14 that follows. The smoothness (surface roughness) of the exhaust gas passage R is 0 at Rmax.
It is 1 mm or less. The annular portions 4 and 5 and the exhaust gas flow passage R are formed so that their cross-sections are gradually reduced in diameter from the inlet side (not shown) toward the terminal end, as shown in FIG. Further, in the right housing half body 3, a well-known waste gate (a bypass passage opened and closed by a valve) not shown is formed between the passage R near the inlet and the discharge passage 9.
Excessive exhaust gas G and the like are released.

In the turbocharger housing 1 as described above, the exhaust gas G discharged from the engine (not shown) is
While being fed from the inlet (not shown) into the flow path R and making one round of the flow path R, as shown by the arrow in FIG.
It is sprayed onto the blade 18 of the turbine 15 through an opening between the exhaust passage 9 and the exhaust passage 9. As a result, since the turbine 15 rotates at a high speed, the compressor (not shown) located at the other end of the shaft 16 can compress the intake gas to the engine and extract a high output.

The turbocharger housing 1 as described above
Is manufactured as follows. The molten metal of the stainless cast steel described above is sucked under reduced pressure into a cavity of a known lost wax mold (not shown). At this time, the core is used only in the above-mentioned waste gate portion. As a result, as shown in FIG. 2, the housing half 2 integrally including the annular portion 4, the cylindrical portion 6, and the stand 10, and the housing half integrally including the annular portion 5, the cylindrical portion 7, and the stand 11. The body 3 and the body 3 are molded separately. Next, the inner peripheral surfaces r1 and r2 of the annular portions 4 and 5 of the housing halves 2 and 3 are smoothed to have a surface roughness Rmax (maximum height) of 0.1 mm or less by, for example, buffing. To be polished.

Further, before or after polishing the inner peripheral surfaces r1 and r2, burrs and surpluses of the annular portions 4 and 5 and the cylindrical portions 6 and 7 are removed, and the average thickness becomes about 1.5 mm. Is polished. As shown in FIG. 2, since the housing halves 2 and 3 have an open shape as a whole, the polishing can be performed easily and accurately. Next, as shown in FIG. 2, the end surfaces 14a and 14b of the housing halves 2 and 3 are butted to form the butted surface 14 that straddles the annular portions 4 and 5 and the stands 10 and 11 as shown in FIG.
Laser welding W using a carbon dioxide laser or a ruby laser is applied from the outside along the abutting surface 14 over the entire circumference. As a result, the housing halves 2 and 3 are integrally joined, and the turbocharger housing 1 shown in FIG. 1 is obtained.

Since the laser welding W has a high concentration of heat energy, a welded portion (weld bead) W having a narrow heat-affected zone can be easily formed. Therefore, it is not necessary to provide a groove in the vicinity of the abutting surface 14, and it is easy to limit the welded portion W in the vicinity of the abutting surface 14, and it is possible to control so that the welding bead W does not project into the exhaust gas passage R. It's easy. Therefore, according to the manufacturing method as described above, it is possible to provide the lightweight turbocharger housing 1 which is excellent in shape and dimensional accuracy and is thin, at low cost. Moreover, in the obtained housing 1, since the flow path R of the exhaust gas G is smooth, it is possible to reduce the turbulence of the gas flow of the gas G and increase the compression efficiency of the intake gas, which is lightweight and high. It is possible to easily cope with performance improvement. In the housing 1, the stands 10 and 11 are provided on the housing halves 2 and 3, but the stand is provided on only one of the housing halves 2 and 3, and the other is provided with the annular portion 4/5 and the cylindrical portion. 6/7
It may be in the form of only one. In this case, the abutting surface 14 is located only between the annular portions 4 and 5.

FIG. 3 shows a cross section of a turbocharger housing 20 of a different form of the invention. As shown in FIG. 3, the turbocharger housing 20 is made up of three casting parts, that is, a turbine side part 21, an intermediate part 26, and a discharge side part 30, which are adjacent to each other at abutting surfaces 38, 39.
It is integrated by welding W. Turbine side parts 2
1 is a wheel 17 of the turbine 15 as shown in FIG.
Has a hollow portion 22 containing therein and a passage R1 for the exhaust gas G
And a stand 24 including a base 25. In addition, the intermediate part 26 has a ring shape as a whole, and a pair of left and right rounded portions 2 that form almost half of the flow paths R1 and R2 of the exhaust gas G that are adjacent to each other in the left and right direction in FIG.
It has 7 and 29, and the partition wall 28 which protrudes in an annular shape obliquely inward from between these. Further, the discharge side component 30 includes a cylindrical portion 31 having a discharge passage 33 therein, and a flow path R of the exhaust gas G.
An annular portion 32 forming approximately half of 2 and a stand 34 including a base 36 are integrally provided. The above parts 21,
26 and 30 are precision casting parts made of the same stainless steel cast steel as described above, and have an average thickness of about 1.5 mm.

Further, as shown in FIG. 3, the parts 21,
A pair of abutting surfaces that are orthogonal to the central axes of the exhaust gas passages R1 and R2 formed by the annular portions 23 and 32 of 26 and 30 and the partition wall 28 and that extend substantially in the radial direction of the passages R1 and R2. The turbocharger housing 30 is formed by laser welding W along 38 and 39. Figure 3
As shown in FIG. 2, the pair of exhaust gas G flow passages R1 and R2 formed by the annular portions 23 and 32 and the partition wall 28 are parallel to each other, and their cross sections are sequentially arranged from the inlet side (not shown) toward the end portion. It is formed so as to have a small diameter, and has a ring-shaped opening between the hollow portion 22 on the right side and the discharge passage 33 on the left side. Along the opening, the tip of the partition wall 28, which extends inward from the intermediate component 26 and has a thin plate-like cross section, faces.
Also, a plurality of blades 18 projecting from the tip side of a wheel 17 fixed to one end of a shaft 16 pivotally supported by a bearing (not shown) are located opposite to the opening.

That is, the flow paths R1 and R2 of the exhaust gas G are arranged in parallel with each other by the partition wall 28, and the partition wall 2 concerned.
Exhaust gas G to the blades 18 of the turbine 15 with 8 in between.
A so-called twin scroll for individually injecting is formed. At the position on the terminal side where the cross section of the flow paths R1 and R2 becomes smaller, the partition wall 28 also becomes lower and the rounded portions 27,
It becomes almost flat between 29. In addition, the discharge side component 30,
This and the parts 26 and 21 include a flow path R1 near the inlet.
A pair of waste gates (a bypass passage opened and closed by a valve) (not shown) are formed in parallel between the R2 and the exhaust passage 33 so that excess exhaust gas G and the like are individually released.

The turbocharger housing 30 as described above
In, the exhaust gas G discharged from the engine (not shown) is sent into the flow paths R1 and R2 from the inlet (not shown),
The blades 18 of the turbine 15 are sprayed from the opening between the hollow portion 22 and the discharge passage 33 as shown by the arrow in FIG. At this time, the exhaust gas G is blown onto the blades 18 substantially in parallel from the flow paths R1 and R2, and therefore gives a high rotational torque to the turbine 15. Therefore, since the turbine 15 rotates at a high speed, the compressor (not shown) located at the other end of the shaft 16 can highly compress the intake gas to the engine and extract a high output.

The turbocharger housing 30 as described above
Is manufactured as follows. The molten metal of the cast stainless steel is vacuum suctioned and cast into the cavity of the same lost wax mold as described above. At this time, the core is used only in the portion which becomes the above-mentioned waste gate. As a result,
As shown in FIG. 2, the turbine-side component 21 integrally including the annular portion 23, the hollow portion 22, and the stand 24, and the partition wall 2
8 and the rounded parts 27 and 29 are integrally formed as an intermediate part 2
6 and the discharge side component 30 that integrally includes the annular portion 32, the cylindrical portion 31, and the stand 34 are individually molded.
Next, burrs and surpluses of the annular portions 23, 32 and the cylindrical portion 31 are removed and polishing is performed so that the average thickness becomes about 1.5 mm. As shown in FIG. 4, since the turbine-side component 21, the intermediate component 26, and the discharge-side component 30 have a substantially open shape as a whole, these polishing operations can be performed easily and accurately.

Then, the inner peripheral surfaces r1 to r1 of the circular ring portions 23 and 32 and the rounded portions 27 and 29 of the parts 21, 26 and 30 are described.
The r4 is polished by, for example, buff polishing. As a result, the surface roughness of these is 0.1 at Rmax (maximum height).
The smoothness is less than or equal to mm. Then, the end face 38 of the component
a, 38b, 39a, 39b are butted against each other, and as shown in FIG. 3, the annular portion 23, the rounded surfaces 27, 29, the annular portion 3
2 and the butting surfaces 38 that straddle the stands 24, 34,
39 is formed. Laser welding W using a carbon dioxide laser or a ruby laser is applied from the outside along the abutting surfaces 38, 39 over the entire circumference. As a result, the parts 21, 26 and 30 are integrally joined, and the turbocharger housing 20 shown in FIG. 3 is obtained.

According to the manufacturing method as described above, it is possible to provide the turbocharger housing 20 which is excellent in shape and dimensional accuracy, is lightweight, and has a thin wall at low cost. Moreover,
The obtained housing 20 has a flow path R for the exhaust gas G.
Since 1 and R2 are smooth, it is possible to reduce the turbulence of the gas flow of the gas G and further improve the compression efficiency of the intake gas, and it is possible to cope with weight reduction and high performance at low cost. In the housing 20, although the stands 24 and 34 are provided on the parts 21 and 30, the stand is provided only on the discharge side part 30, and the turbine side part 21 includes only the annular portion 23 and the hollow portion 22, Intermediate part 2
6 may have a configuration including only the partition wall 28 and the rounded surfaces 27 and 29. In this case, the abutting surfaces 38 and 39 are located between the annular portions 23 and 32.

The present invention is not limited to each of the forms described above. For example, the housing halves 2 and 3 and the components 21, 26 and 30 may be made of stainless steel other than the cast stainless steel, or other heat resistant steel. In addition, the turbocharger housing 20
In regard to the material of the turbine side component 21 and the discharge side component 30, the material of the intermediate component 26 including the partition wall 28 may be a steel type having further superior heat resistance. Furthermore, the method of casting the cast parts such as the housing halves 2 and 3 is not limited to the casting method using the lost wax mold, but may be a sand casting method, a shell molding method, a hardening molding method, a V process, or the like. It is possible. Further, the welding W is
Not limited to laser welding and electron beam welding, MIG welding, T
IG welding, high frequency welding, or ultrasonic welding may be used. The turbocharger housing to which the present invention is applied includes not only automobile engine engines but also various aircraft engine configurations.

[0025]

According to the turbocharger housing (Claim 1) of the present invention described above, a plurality of cast parts having no or few hollows are welded at the abutting surfaces, so that the thinning and It becomes a turbocharger housing that has been made lighter. Moreover, since the surface of the exhaust gas passage (scroll) in each individual cast part is smoothed with high precision, it is possible to reduce turbulence of the gas flow and increase the compression efficiency of the intake gas. Further, according to the turbocharger housing of claims 2 and 3, since the turbocharger housing is formed of three cast parts, it is thin and lightweight even if it has a complicated shape or structure such as a so-called twin scroll. The surface of the flow path of the exhaust gas is made smooth, resulting in a high-performance turbocharger housing with excellent shape and dimensional accuracy.

On the other hand, according to the method for manufacturing a turbocharger housing of the present invention (claim 4), a plurality of cast parts having no hollow portion are welded at the abutting surfaces, so that they are thin and lightweight and exhaust gas is exhausted. The surface of the passage (scroll) can be made smooth, and an excellent turbocharger housing can be reliably provided at low cost. According to the method of manufacturing a turbocharger housing of claim 5, a high-performance turbocharger housing having a so-called twin scroll that is thin and lightweight and has a smooth exhaust gas flow path can be reliably provided. Can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a turbocharger housing of the present invention.

2 is a cross-sectional view showing two cast parts forming the turbocharger housing of FIG.

FIG. 3 is a cross-sectional view schematically showing a turbocharger housing having a different configuration.

4 is a cross-sectional view showing three cast parts forming the turbocharger housing of FIG.

[Explanation of symbols]

1,20 ………… Turbocharger housing 2,3 ……………… Housing half (cast parts) 14,38,39 ... Butt faces 21 ……………… Turbine side parts (cast parts) 26 ……………… Intermediate parts (casting parts) 28 ……………… Partition wall 30 ……………… Discharge side parts (cast parts) G …………………… Exhaust gas R, R1, R2 ... Channel W …………………… Laser welding (welding)

Claims (5)

[Claims] 1. A plurality of cast parts which have a built-in exhaust gas flow path having a substantially circular shape, and are butted against each other at a surface which is substantially orthogonal to the central axis of the flow path and which is substantially along the radial direction of the flow path. The turbocharger housing is characterized in that the plurality of cast parts are welded to each other at their butt surfaces. 2. The exhaust gas flow paths are substantially parallel to each other.
Three cast parts that are abutted with two surfaces that are made up of two flow paths and that are substantially orthogonal to the central axes of the two flow paths and that are substantially along the radial direction of the two flow paths. The turbocharger housing according to claim 1. 3. A casting part located in the middle among the three casting parts has a partition wall projecting along the circumferential direction of the inner side surface thereof for partitioning the two flow paths. The turbocharger housing according to claim 2. 4. A plurality of casting parts each of which has a substantially circular exhaust gas passage and is divided into planes which are substantially orthogonal to the central axis of the passage and are substantially along the radial direction of the passage. A method of manufacturing a turbocharger housing, comprising: a step of casting into a plurality of parts; and a step of welding the obtained plurality of cast parts at their abutting surfaces. 5. The exhaust gas flow paths are substantially parallel to each other.
A step of casting three casting parts that are abutted by two surfaces that are made up of two flow paths and that are substantially orthogonal to the central axes of the two flow paths and that are substantially along the radial direction of the two flow paths; Welding three cast parts along the two abutting surfaces.
A method of manufacturing a turbocharger housing according to claim 1.