JP6922707B2 - How to manufacture the compressor housing - Google Patents

Description

The present invention relates to a method for manufacturing a compressor housing.

Patent Document 1 describes a turbine housing in a turbocharger. The turbine housing of Patent Document 1 is connected to an accommodating portion in which a turbine wheel is accommodated, a scroll passage that is connected to the accommodating portion and extends in an arc shape so as to surround the accommodating portion, and the accommodating portion, and exhausts exhaust gas to the outside. It has a discharge passage.

Further, Patent Document 1 discloses a method of manufacturing the turbine housing by casting. In this casting method, a sand core for forming the internal space of the scroll passage is arranged between the first mold portion and the second mold portion. Of the pair of mold parts, the first mold part corresponds to the shape of the bearing housing side part of the turbine housing, and the second mold part corresponds to the shape of the exhaust discharge side part of the turbine housing. There is. Then, the molten metal is poured into the cavity partitioned by the first mold portion and the second mold portion. After the molten metal has hardened, the hardened metal is taken out from the first mold part and the second mold part to break the core. In this way, a turbine housing having a scroll passage having a desired shape is formed.

In the casting method of Patent Document 1, the core includes a main body portion having the same shape as the internal space of the scroll passage, and a leg portion protruding from the main body portion. Then, in the cavity partitioned by the first mold portion and the second mold portion, the leg portion of the core is projected into the space corresponding to the accommodating portion in the turbine housing, and the leg portion of the core is the first mold in the space. It is supported by the part and the second type part.

International Publication No. 2009/052883

Similar to the turbine housing, the compressor housing in the turbocharger is connected to the accommodating portion in which the compressor wheel is accommodated, the accommodating portion, the introduction passage for introducing the intake air into the accommodating portion, and is connected to the accommodating portion and surrounds the accommodating portion. It is equipped with a scroll passage that extends in an arc shape. Further, in the turbocharger, in particular, by making the shape of the wall portion of the accommodating portion in the compressor housing into a shape corresponding to the shape of the outer peripheral portion of the compressor wheel, efficient compression of the intake air is realized.

When the method of casting the turbine housing of Patent Document 1 is applied to the compressor housing, the leg portion of the core corresponds to the accommodating portion in the compressor housing in the cavity partitioned by the first mold portion and the second mold portion. It will protrude into the space. Then, in order to properly support the core through the legs of the core, it is necessary to secure an appropriate size as the size of the legs. The presence of the core leg limits the degree of freedom in designing the scroll passage and accommodating portion, and the scroll passage, accommodating portion, and compressor wheel may not be designed in the desired shape that can realize efficient compression of intake air. There is.

A method for manufacturing a compressor housing for solving the above problems is connected to an accommodating portion in which a compressor wheel is accommodated, an introduction passage for introducing intake air into the accommodating portion, and the accommodating portion. A method for manufacturing a compressor housing in a turbocharger having a scroll passage extending in an arc shape so as to surround the accommodating portion, wherein the main body portion having a shape corresponding to the scroll passage and the turbocharger when the compressor housing is molded. After the manufacturing process of manufacturing a core having a leg portion protruding from the main body toward the intake introduction side opposite to the bearing housing side or the radial outside with respect to the central axis of the compressor wheel, and after the manufacturing process. It has a first mold portion having a shape corresponding to the portion on the bearing housing side of the compressor housing and a shape corresponding to the portion on the intake introduction side of the compressor housing, and supports the leg portion in the core. After the casting step in which the second mold portion is arranged to face each other and the core is arranged between the first mold portion and the second mold portion, the molten metal is poured and hardened, and after the casting step. It includes a removing step of removing the core from the inside of the solidified metal, and a closing step of closing the hole in the wall portion of the scroll passage formed by the position of the leg portion after the removing step. ..

In the above configuration, in the casting process, the leg portion of the core is supported by the second mold portion corresponding to the shape on the intake intake side. On the other hand, the configuration for supporting the core in the cavity partitioned by the first mold portion and the second mold portion is radially inside the cavity and on the bearing housing side of the portion corresponding to the scroll passage. There is no need to project into the space corresponding to the located housing. Therefore, the shape of the scroll passage and the accommodating portion in the compressor housing is not easily restricted by the leg portion of the core, and the degree of freedom in designing the scroll passage, the accommodating portion and the compressor wheel is improved. As a result, it becomes easy to design the shapes of the scroll passage, the accommodating portion, and the compressor wheel into a shape that can realize efficient intake compression. In the above configuration, a hole corresponding to the leg of the core is formed in the wall portion that divides the scroll passage, but since the hole in the wall portion of the scroll passage is closed in the closing step, the hole in the wall portion of the scroll passage is closed. There is no particular problem.

Sectional view of the turbocharger. Side view of the compressor housing. Explanatory drawing which shows the manufacturing process of a compressor housing. Explanatory drawing which shows the manufacturing process of a compressor housing.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4. First, the configuration of the turbocharger 100 mounted on the vehicle will be described.
As shown in FIG. 1, the turbocharger 100 includes a compressor housing 10 attached to an intake passage of an internal combustion engine, a turbine housing (not shown) attached to an exhaust passage of an internal combustion engine, and a bearing housing connecting the compressor housing 10 and the turbine housing. It has 40 and. In the following description, as shown in FIG. 1, the side where the bearing housing 40 is located (the right side in FIG. 1) is the bearing housing 40 side, and the side opposite to the bearing housing 40 side (the left side in FIG. 1) is introduced by intake air. Explain as the side.

The bearing housing 40 includes a shaft-shaped portion 41 having a substantially cylindrical shape. An insertion hole 41a penetrates the shaft-shaped portion 41 on the central axis X of the shaft-shaped portion 41. A substantially disk-shaped fixing portion 42 extends outward in the radial direction from the end portion of the shaft-shaped portion 41 on the intake side.

A compressor housing 10 made of an aluminum alloy is fixed to the fixing portion 42 of the bearing housing 40. As shown in FIGS. 1 and 2, the compressor housing 10 has a cylindrical tubular portion 11 extending in the central axis X direction of the axial portion 41 of the bearing housing 40, and an arc portion 12 surrounding the outer circumference of the tubular portion 11. And have. The arc portion 12 is arranged so as to surround the outer periphery of the end portion of the tubular portion 11 on the bearing housing 40 side in the axial direction of the tubular portion 11.

As shown in FIG. 1, a part of the internal space of the tubular portion 11 on the bearing housing 40 side is an accommodating portion 22 in which the compressor wheel 51 is accommodated. The inner diameter of a part of the tubular portion 11 on the bearing housing 40 side is larger toward the bearing housing 40 side. In other words, the diameter of the accommodating portion 22 is larger toward the bearing housing 40 side. Of the internal space of the tubular portion 11, a part of the intake intake side is an introduction passage 21 for introducing intake air into the accommodating portion 22. That is, the introduction passage 21 is connected to the accommodating portion 22.

As shown in FIG. 2, two plate-shaped mounting portions 31 project from the upstream end (the end on the intake air introduction side) of the tubular portion 11 in the intake air flow direction. In the mounting portion 31, the bolt hole 31a penetrates in the thickness direction of the mounting portion 31. By inserting a bolt (not shown) into the bolt hole 31a, the tubular portion 11 (compressor housing 10) is fixed to the intake passage on the upstream side of the turbocharger 100 in the internal combustion engine.

As shown in FIGS. 1 and 2, a scroll passage 23 extending in an arc shape is partitioned inside the arc portion 12 so as to surround the accommodating portion 22 in the tubular portion 11. As shown in FIG. 2, the scroll passage 23 extends over substantially the entire circumferential direction of the tubular portion 11. Further, a part of the scroll passage 23 on the downstream side in the intake flow direction extends in the tangential direction with respect to the outer peripheral circle of the tubular portion 11. A flange portion 32 projects outward from the downstream end of the arc portion 12 in the intake flow direction with respect to the central axis of the scroll passage 23. A bolt hole (not shown) penetrates the flange portion 32 in the thickness direction, and when the bolt is inserted into the bolt hole, the arc portion 12 (compressor housing 10) becomes larger than the turbocharger 100 in the internal combustion engine. It is fixed to the intake passage on the downstream side.

As shown in FIG. 1, the end surface 12a on the bearing housing 40 side of the arc portion 12 is fixed to the end surface 42a on the intake introduction side of the fixing portion 42 of the bearing housing 40. Further, a gap is secured between the end surface 11a on the bearing housing 40 side of the tubular portion 11 and the end surface 42a on the intake introduction side of the fixed portion 42 of the bearing housing 40. This gap functions as a connecting passage 24 that connects the accommodating portion 22 in the tubular portion 11 and the scroll passage 23 in the arc portion 12. That is, the scroll passage 23 is connected to the accommodating portion 22 via the connecting passage 24.

As shown in FIG. 1, a screw hole 26 penetrates through a portion of the arc portion 12 that constitutes the wall portion of the scroll passage 23. The screw hole 26 is located on the intake side of the arc portion 12. As shown in FIG. 2, in the present embodiment, three screw holes 26 penetrate through the arc portion 12. The three screw holes 26 are arranged at intervals in the circumferential direction of the scroll passage 23.

As shown in FIG. 1, a plug 35 is inserted through the screw hole 26. The shaft portion 36 of the plug 35 is screwed into the screw hole 26. In this embodiment, the tip of the shaft portion 36 of the plug 35 does not protrude from the inner wall (the wall that partitions the scroll passage 23) of the arc portion 12. The head 37 of the plug 35 is located outside the screw hole 26.

As shown in FIG. 1, the accommodating portion 22 of the compressor housing 10 accommodates a substantially cylindrical compressor wheel 51. The central axis of the compressor wheel 51 is located coaxially with the central axis X. A slight gap is secured between the outer peripheral portion of the compressor wheel 51 and the wall portion of the accommodating portion 22 in the tubular portion 11. In FIG. 1, the gap between the outer peripheral portion of the compressor wheel 51 and the wall portion of the accommodating portion 22 in the tubular portion 11 is omitted.

One end of a substantially rod-shaped connecting shaft 52 is connected to the compressor wheel 51. The connecting shaft 52 is inserted into the insertion hole 41a of the bearing housing 40. The central axis of the connecting shaft 52 is located coaxially with the central axis X. The connecting shaft 52 is rotatably supported by bearings (not shown). A turbine wheel (not shown) is connected to the other end of the connecting shaft 52. The turbine wheel is housed inside the turbine housing. When the compressor wheel 51 rotates with the rotation of the turbine wheel, the compressor wheel 51 compresses the intake air.

Next, a method of manufacturing the compressor housing 10 will be described.
First, in the manufacturing process, the sand core 70 used in the subsequent casting process is manufactured. When manufacturing the core 70, the inside of the metal core mold formed according to the outer shape of the core 70 is sufficiently filled with sand to harden the sand. Then, the core 70 is formed by taking out the solidified sand from the core mold.

As shown in FIG. 3, the core 70 includes a main body portion 71 having a shape corresponding to the internal space of the scroll passage 23. That is, the main body 71 extends in an arc shape substantially similar to the shape of the scroll passage 23. A substantially cylindrical leg portion 72 protrudes from the main body portion 71. The legs 72 project toward the intake intake side when the compressor housing 10 is molded. The outer diameter of the leg portion 72 is smaller than the inner diameter of the screw hole 26 provided in the compressor housing 10 after manufacturing. The position of the leg portion 72 with respect to the main body portion 71 in the core 70 is substantially the same as the position of the screw hole 26 with respect to the scroll passage 23 in the compressor housing 10 (arc portion 12). The core 70 includes three legs 72.

After that, in the casting process, as shown in FIG. 3, the first mold portion 81, which is a metal mold having a shape corresponding to the portion on the bearing housing 40 side of the compressor housing 10, and the intake air introduction side of the compressor housing 10 A second mold portion 82, which is a metal mold having a shape corresponding to the portion of the above, is used. The first mold portion 81 includes a mold portion main body 81a having a substantially square plate shape, and a forming protrusion 81b that protrudes toward the intake air introduction side when the compressor housing 10 is molded from the mold portion main body 81a. The forming protrusion 81b protrudes corresponding to the shapes of the end surface 12a of the arc portion 12 in the compressor housing 10, the scroll passage 23, the end surface 11a of the tubular portion 11, and the accommodating portion 22.

The second mold portion 82 has a substantially quadrangular prism shape. From the end surface on the bearing housing 40 side when the compressor housing 10 is molded in the second mold portion 82, the formed recess 82a is recessed toward the intake air introduction side when the compressor housing 10 is molded. The forming recess 82a is recessed corresponding to the shapes of the outer surface of the arc portion 12 on the intake introduction side of the compressor housing 10, the outer surface of the tubular portion 11 on the intake introduction side, the introduction passage 21, and the accommodating portion 22.

The support recess 82b is recessed from the portion of the formed recess 82a of the second mold portion 82 corresponding to the outer surface of the arc portion 12 toward the intake air introduction side when the compressor housing 10 is molded. The inner diameter of the support recess 82b is substantially the same as the outer diameter of the leg portion 72 of the core 70. The position of the support recess 82b with respect to the forming recess 82a in the second mold portion 82 is substantially the same as the position of the leg portion 72 with respect to the main body portion 71 in the core 70. The second mold portion 82 includes three support recesses 82b.

As shown in FIG. 3, in the casting process, first, the core 70 is arranged inside the forming recess 82a of the second mold portion 82. Then, the three leg portions 72 of the core 70 are inserted into the three support recesses 82b of the second mold portion 82, and the leg portions 72 of the core 70 are supported by the second mold portion 82. Next, the first mold portion 81 is arranged so that the forming recess 82a of the second mold portion 82 and the forming protrusion 81b of the first mold portion 81 face each other. In this way, the core 70 is arranged in the cavity partitioned between the first mold portion 81 and the second mold portion 82. Then, with the core 70 arranged between the first mold portion 81 and the second mold portion 82, the molten aluminum alloy is formed in the cavity partitioned between the first mold portion 81 and the second mold portion 82. To solidify the aluminum alloy.

As shown in FIG. 4, after that, in the removing step, the solidified aluminum alloy is taken out from between the first mold portion 81 and the second mold portion 82. Then, the core 70 inside the solidified aluminum alloy is broken and the sand is discharged. In this way, the introduction passage 21, the accommodating portion 22, and the scroll passage 23 in the compressor housing 10 are formed. Further, a leg insertion hole 26A in which the leg portion 72 of the core 70 is located is formed in a portion of the compressor housing 10 (arc portion 12) that constitutes the scroll passage 23.

Further, in the removing step, the sand remaining on the inner surface and the outer surface of the compressor housing 10 is removed by a shot blasting process in which metal balls collide with each other. Then, a metal ball is introduced from the three leg insertion holes 26A into the inside of the arc portion 12 (scroll passage 23) in the compressor housing 10 to perform shot blasting.

After that, in the closing step, the leg insertion hole 26A is made into the screw hole 26 by forming a thread groove in the leg insertion hole 26A in the compressor housing 10 by cutting. Then, as shown in FIG. 1, the shaft portion 36 of the plug 35 is screwed into the screw hole 26, and the plug 35 is inserted into the screw hole 26. That is, the screw hole 26 in the wall portion of the scroll passage 23 in the compressor housing 10 (arc portion 12) is closed by the plug 35.

The operation and effect of this embodiment will be described.
In the present embodiment, as shown in FIG. 3, in the casting process, the three leg portions 72 of the core 70 are inserted into the three support recesses 82b of the second mold portion 82, whereby the core 70 The leg portion 72 is supported by the second mold portion 82 having a shape corresponding to the portion on the intake side. Here, tentatively, in the cavity partitioned between the first mold portion 81 and the second mold portion 82, the leg portion 72 of the core 70 projects toward the space side corresponding to the accommodating portion 22 in the compressor housing 10. If so, the leg portion 72 of the core 70 is supported by the first mold portion 81. When the legs 72 of the core 70 are supported through the space corresponding to the accommodating portion 22 in this way, the shapes of the scroll passage 23 and the accommodating portion 22 in the compressor housing 10 are likely to be restricted. In this case, the degree of freedom in designing the scroll passage 23 and the accommodating portion 22 is restricted, and the scroll passage 23, the accommodating portion 22, and the compressor wheel 51 in the compressor housing 10 have a desired shape capable of efficiently compressing the intake air. It may not be possible to design.

On the other hand, in the present embodiment, the legs 72 of the core 70 project toward the intake intake side when the compressor housing 10 is molded. Then, in the casting process, the leg portion 72 of the core 70 is supported by the second mold portion 82. On the other hand, the configuration for supporting the core 70 in the cavity partitioned by the first mold portion 81 and the second mold portion 82 is radially inside the cavity and inward with respect to the portion corresponding to the scroll passage 23. It is not necessary to project into the space corresponding to the accommodating portion 22 located on the bearing housing 40 side. Therefore, the shapes of the scroll passage 23 and the accommodating portion 22 in the compressor housing 10 are not easily restricted. As a result, the degree of freedom in designing the scroll passage 23, the accommodating portion 22, and the compressor wheel 51 in the compressor housing 10 can be improved. As a result, it becomes easy to design the shapes of the scroll passage 23, the accommodating portion 22, and the compressor wheel 51 in the compressor housing 10 into a shape that can realize efficient intake compression.

Further, in the casting process, the leg insertion hole 26A is formed because the leg portion 72 of the core 70 is located on the wall portion forming the scroll passage 23 in the compressor housing 10 (arc portion 12). In the present embodiment, in the subsequent closing step, the leg insertion hole 26A is made into a screw hole 26 by cutting. Then, the screw hole 26 in the wall portion of the scroll passage 23 in the compressor housing 10 (arc portion 12) is closed by the plug 35. Therefore, for example, when the turbocharger 100 is supercharged, problems such as intake air leaking from the screw holes 26 in the compressor housing 10 do not occur.

By the way, in the removing step, for example, when a metal ball is introduced into the scroll passage 23 from the downstream end side of the scroll passage 23 and the shot blasting process is performed, the scroll passage 23 extends in an arc shape. The shot blasting process may not completely remove the sand remaining inside the scroll passage 23. On the other hand, in the present embodiment, by introducing a metal ball into the scroll passage 23 from the three leg insertion holes 26A in the compressor housing 10 and performing a shot blast process, every corner inside the scroll passage 23 is performed. Metal balls are likely to collide with each other. Thereby, the sand inside the scroll passage 23 in the compressor housing 10 can be appropriately removed. Further, by performing the shot blasting process so as to collide the metal balls with the corners inside the scroll passage 23, it is possible to contribute to the improvement of the surface properties on the inner surface, such as improving the smoothness of the inner surface of the scroll passage 23.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-In the above configuration, the shape of the core 70 can be changed as appropriate. For example, even if the number of legs 72 is changed, if the core 70 can be supported by the second mold portion 82 in the casting process, the number of legs 72 in the core 70 may be two or less or four or more. good. In this case, the number of support recesses 82b in the second mold portion 82 may be changed according to the number of legs 72.

Further, if the core 70 can be supported by the second mold portion 82 in the casting process, the position of the leg portion 72 with respect to the main body portion 71 in the core portion 70, the size of the leg portion 72, and the shape of the leg portion 72 are appropriately adjusted. Can be changed.

-In the above configuration, the protruding direction of the leg portion 72 in the core 70 may be changed. For example, the legs 72 may project outward in the radial direction with respect to the central axis of the compressor wheel 51 of the turbocharger 100 when the compressor housing 10 is molded. Then, in the casting step, the leg portion 72 of the core 70 may be supported by the second mold portion 82. Also in this case, the shapes of the scroll passage 23 and the accommodating portion 22 in the compressor housing 10 are less likely to be restricted.

In the above configuration, the tip of the shaft portion 36 of the plug 35 may protrude from the inner wall (the wall that partitions the scroll passage 23) of the arc portion 12. For example, if the influence on the flow of the intake air flowing through the scroll passage 23 is small, the length of the shaft portion 36 in the plug 35 may be appropriately changed.

-In the closing step in the above configuration, the configuration for closing the leg insertion hole 26A in the compressor housing 10 may be appropriately changed. For example, in the closing step, the leg insertion hole 26A may be closed by press-fitting a metal ball into the leg insertion hole 26A in the compressor housing 10. In this case, the work of cutting the leg insertion hole 26A in the compressor housing 10 into the screw hole 26 can be omitted.

-In the above configuration, the working method of the shot blasting process in the removing step may be changed. For example, if the sand inside the scroll passage 23 can be appropriately removed by the shot blasting process of introducing a metal ball into the scroll passage 23 from the downstream end side of the scroll passage 23, the scroll can be scrolled from the leg insertion hole 26A. It is not necessary to perform the shot blasting process for introducing the metal ball into the passage 23.

-In the above configuration, the material of the compressor housing 10 can be changed as appropriate. For example, the material of the compressor housing 10 may be cast iron. In this case, the first mold portion 81 and the second mold portion in the casting step may be a sand mold made of sand.

X ... central axis, 10 ... compressor housing, 11 ... tubular part, 11a ... end face, 12 ... arc part, 12a ... end face, 21 ... introduction passage, 22 ... accommodating part, 23 ... scroll passage, 24 ... connection passage, 26 ... Screw hole, 26A ... Leg insertion hole, 31 ... Mounting part, 31a ... Bolt hole, 32 ... Flange part, 35 ... Plug, 36 ... Shaft part, 37 ... Head, 40 ... Bearing housing, 41 ... Shaft-shaped part , 41a ... Insertion hole, 42 ... Fixed part, 42a ... End face, 51 ... Compressor wheel, 52 ... Connecting shaft, 70 ... Core, 71 ... Main body part, 72 ... Leg part, 81 ... First mold part, 81a ... Type Part body, 81b ... Forming protrusion, 82 ... Second mold part, 82a ... Forming recess, 82b ... Support recess, 100 ... Turbocharger.

Claims (1)

An accommodating portion in which the compressor wheel is accommodated, an introduction passage connected to the accommodating portion and introducing intake air into the accommodating portion, and a scroll passage connected to the accommodating portion and extending in an arc shape so as to surround the accommodating portion. It is a manufacturing method of the compressor housing in the turbocharger equipped with.
The main body having a shape corresponding to the scroll passage, and the main body toward the intake introduction side on the side opposite to the bearing housing side of the turbocharger when the compressor housing is molded, or the outer side in the radial direction with respect to the central axis of the compressor wheel. The manufacturing process of manufacturing a core with legs protruding from the part,
After the manufacturing process, the first mold portion having a shape corresponding to the portion on the bearing housing side of the compressor housing , the forming recess corresponding to the shape of the portion on the intake side of the compressor housing, and the recessed portion. Casting in which a second mold portion having a recessed support recess is placed facing each other from the forming recess, and the core is placed between the first mold portion and the second mold portion, and the molten metal is poured and hardened. Process and
After the casting step, a removal step of removing the core from the inside of the solidified metal, and a removal step.
After the removal step, a closing step of closing the hole in the wall portion of the scroll passage formed by the position of the leg portion is provided .
A method for manufacturing a compressor housing, characterized in that, in the casting step, the leg portion is inserted into the support recess and the leg portion is supported by the second mold portion.

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