JP2013231405A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbocharger of which the inner peripheral edge side of a heat shield plate is surely prevented from contacting a turbine impeller.SOLUTION: A turbocharger includes a turbine impeller 12 provided to a rotary shaft 11, a turbine housing 13, a bearing housing 14, and an annular heat shield plate 15 provided opposite to the back 12a of the turbine impeller 12. An outer peripheral edge 21 of the heat shield plate 15 is held between the turbine housing 13 and the bearing housing 14. The inner peripheral side of the outer peripheral edge 21 extends toward the turbine impeller 12 and then bends or winds, extending to the opposite direction of the turbine impeller 12 and toward the rotary shaft 11 to form a first top part 22, and then bends or winds to the opposite direction of the first top part 22, extending toward the rotary shaft 11 to form a second top part 23.

Description

  The present invention relates to a turbocharger.

  2. Description of the Related Art Conventionally, a turbocharger (supercharger) is known which is driven by using its exhaust energy to increase the supply pressure of the internal combustion engine and increase the output of the internal combustion engine. Yes.

  A turbocharger generally includes a compressor (compressor) and a turbine arranged with a bearing housing interposed therebetween, and the compressor incorporates a compressor impeller and the turbine incorporates a turbine impeller. The compressor impeller and the turbine impeller are connected to each other by a rotating shaft (shaft) supported by a bearing in a bearing housing. As a result, the turbine impeller is rotationally driven by the exhaust gas of the internal combustion engine such as an engine, and this rotational force is transmitted to the compressor impeller by the rotating shaft, and the air is compressed by the compressor impeller, thereby increasing the supply pressure to the internal combustion engine. It is like that. That is, it is supercharged.

  In such a turbocharger, since the turbine housing side becomes hot, an annular heat shield is provided in order to prevent heat from being transferred to the bearing housing side, which is cooled at a relatively low temperature. (For example, refer to Patent Document 1). The heat shield plate is attached to the surface of the bearing housing facing the turbine impeller side by holding the outer peripheral edge portion between the attachment surface of the turbine housing and the attachment flange of the bearing housing. Further, this heat shield plate normally forms an apex portion in which the inner peripheral side thereof is directed toward the impeller from the outer peripheral edge portion, and subsequently bent or curved toward the direction away from the impeller.

Japanese Patent Laid-Open No. 2007-113501

By the way, the heat shield plate having the above structure is manufactured not only by a casting method but also by sheet metal processing such as press working and drawing. Since the heat shield plate manufactured by such sheet metal processing forms the top portion by bending or bending a flat plate, residual stress is generated at the top portion. Since this residual stress is released by being heated, the heat shield plate receives heat from the turbine housing side to release the residual stress at the top when the turbocharger is operated.
However, when the residual stress is released at the top portion in this way, the angle of the top portion is expanded, and the inner peripheral edge side of the heat shield plate is displaced toward the turbine impeller side, which may cause contact with the turbine impeller.

  In order to prevent the heat shield from coming into contact with the turbine impeller by releasing the residual stress in this way, for example, it is conceivable to change the position of the top portion. However, the position of the top of the turbine impeller and the distance (clearance) between them are for the purpose of suppressing the leakage of gas (air) from the turbine housing side to the rotating shaft side and the inflow of foreign matter such as combustion residues. The current situation is that it cannot be changed and therefore it is difficult to reliably prevent the heat shield from contacting the turbine impeller.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a turbocharger that reliably prevents the inner peripheral edge side of the heat shield plate from coming into contact with the turbine impeller. .

A turbocharger according to the present invention includes a turbine impeller provided on a rotating shaft, a turbine housing that houses the turbine impeller, a bearing housing, and an annular heat shield provided to face the back surface of the turbine impeller. With
The heat shield plate has an outer peripheral edge portion held between the turbine housing and the bearing housing, and an inner peripheral side of the outer peripheral edge portion is bent or curved continuously toward the turbine impeller, so that the turbine impeller The first apex is formed by moving toward the direction away from the rotation axis and toward the rotation axis, and then bending or bending in the direction opposite to the bending or bending direction toward the rotation axis side. It forms the top part, It is characterized by the above-mentioned.

  Further, in the turbocharger, the second top portion is formed opposite to a step portion provided on the turbine impeller and defining a concave portion serving as a balance correcting portion for correcting the balance of the rotating shaft. Preferably it is.

  According to the turbocharger of the present invention, the heat shield plate forms a second top portion that is bent or curved in a direction opposite to a direction in which the first top portion is bent or curved on the inner peripheral side from the first top portion. Therefore, the opening angle of the first top can be made smaller than that of the conventional top. That is, conventionally, the opening angle of the top portion (the first top portion of the present invention) should be reduced in advance so that the inner peripheral edge side of the heat shield plate does not contact the turbine impeller even when the residual stress is released and the top portion angle increases. However, since the inner peripheral edge side is interfered with the bearing housing, the opening angle cannot be sufficiently reduced.

On the other hand, in the present invention, since the second top portion is formed, it is possible to prevent the inner peripheral edge side of the heat shield plate from being interfered with the bearing housing, and thus the opening angle of the first top portion can be reduced. It can be made sufficiently small. Therefore, even when the residual stress is released and the angle of the first top portion is expanded, the inner peripheral edge side of the heat shield plate can be prevented from contacting the turbine impeller.
Also, when the residual stress at the first top portion is released by heating and the angle at the first top portion is expanded, the residual stress is also released at the second top portion, so that the angle is expanded. As a result, the inner peripheral edge side of the heat shield plate is displaced in a direction away from the turbine impeller, so that the inner peripheral edge side is more reliably prevented from coming into contact with the turbine impeller.

1 is a schematic configuration diagram of an embodiment of a turbocharger according to the present invention. It is a principal part enlarged view of FIG. (A), (b) is a principal part side view which shows the modification of a heat shield. It is a figure which shows another modification of a heat shield, and is an expanded side sectional view of an outer periphery part.

  Hereinafter, an embodiment of a turbocharger (supercharger) according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed to make each member a recognizable size.

  FIG. 1 is a schematic configuration diagram of an embodiment of a turbocharger according to the present invention. In FIG. 1, reference numeral 10 denotes a turbocharger. The turbocharger 10 includes a rotating shaft 11, a turbine impeller 12, a turbine housing 13, a bearing housing 14, a heat shield plate 15, and the like. In FIG. 1, the illustration of the compressor housing is omitted.

  The rotating shaft 11 has a turbine impeller 12 at one end (left end in FIG. 1), and the turbine impeller 12 is accommodated in a turbine housing 13. In the present embodiment, the turbine impeller 12 is formed integrally with the rotary shaft 11. However, this invention is not limited to this, The structure which attaches the turbine impeller 12 separately may be sufficient.

  The turbine impeller 12 includes a turbine hub 16 connected to one end of the rotary shaft 11 and a plurality of turbine blades 17 provided on the outer peripheral surface of the turbine hub 16. The turbine blades 17 extend in the axial direction of the turbine hub 16 and extend radially outward, and are disposed at a predetermined interval in the circumferential direction of the turbine hub 16.

  Further, as shown in FIG. 2, which is an enlarged view of the main part of FIG. 1, a rear surface 12a of the turbine impeller 12 (back surface of the turbine hub 16), that is, a surface on the bearing housing 14 side, is partially recessed in the outer peripheral portion thereof. 16a is formed. Thus, a step 16b is formed between the recess 16a and the inner peripheral side.

  A compressor impeller 18 is connected to the other end (right end in FIG. 1) of the rotating shaft 11. The compressor impeller 18 is fixed to the rotating shaft 11 by a shaft end nut (not shown), and is configured to rotate integrally with the rotating shaft 11 in the same manner as the turbine impeller 12. The compressor impeller 18 is accommodated in a compressor housing (not shown).

  The bearing housing 14 has a radial bearing 19, and the rotary shaft 11 is rotatably supported by the radial bearing 19. The radial bearing 19 is a bearing metal on the turbine side and the compressor side, and is preferably a hollow cylindrical floating metal or a semi-floating metal. The rotary shaft 11 is supported by the thrust bearing 20 so as not to move in the axial direction. The thrust bearing 20 includes a pair of disk-shaped thrust collars 20 a that rotate together with the rotating shaft 11, and a thrust bearing 20 b that is held between the thrust collars 20 a and 20 a and is fixed to the bearing housing 14. .

  With such a configuration, the turbocharger 10 rotationally drives the turbine impeller 12 with the exhaust gas of the engine (internal combustion engine), transmits this rotational force to the compressor impeller 18 through the rotating shaft 11, and compresses the air with the compressor impeller 18. The engine is supercharged.

  Further, a heat shield plate 15 is disposed between the turbine housing 13 and the bearing housing 14. The heat shield plate 15 has an annular plate shape, and is formed by sheet metal processing such as press working or drawing in the present embodiment. As shown in FIGS. 1 and 2, the heat shield 15 has a bowl-shaped outer peripheral edge 21 sandwiched between a seal surface (mounting surface) 13 a of the turbine housing 13 and a mounting flange 14 a of the bearing housing 14. Thus, the turbine impeller 12 is attached between the turbine housing 13 and the bearing housing 14 with the rotating shaft 11 side being extrapolated. That is, the turbine impeller 12 is disposed so as to face the rear surface 12a (the rear surface of the turbine hub 16).

  As shown in FIG. 2, a first top portion 22 and a second top portion 23 are formed on the heat shield plate 15 from the outer peripheral edge portion 21 toward the inner peripheral side. The first top portion 22 is formed on the turbine impeller 12 after the inner peripheral side of the outer peripheral edge portion 21 sandwiched between the seal surface 13a of the turbine housing 13 and the mounting flange 14a of the bearing housing 14 is pulled out from between these. It is a corner portion formed by facing and subsequently bending or curving toward the direction away from the turbine impeller 12 and toward the rotating shaft 11.

The first top portion 22 is formed at substantially the same position as the top portion formed on the conventional heat shield plate, and is disposed close to the turbine impeller 12 with a predetermined clearance, whereby the turbine housing 13 is arranged. It is possible to prevent gas (air) from leaking from the side to the rotating shaft 11 side and foreign matters such as combustion residues from flowing into the rotating shaft 11 side.
In this embodiment, the opening angle θ1 of the first top portion 22 is sufficiently smaller than the opening angle of the conventional top portion. For example, the opening angle of the conventional top portion is about 90 ° to 100 °, whereas the opening angle θ1 of the first top portion 22 of the present embodiment is about 70 ° to 85 °.

  Here, since the first top portion 22 is formed by pressing or drawing as described above, a compressive force acts on the inside, and a tensile force acts on the outside. Therefore, a residual stress is generated in the first top portion 22, and the opening angle θ1 is expanded by releasing the residual stress by being heated during operation as will be described later.

  The second top portion 23 is bent or curved after the inner peripheral side (of the heat shield plate 15) is directed away from the turbine impeller 12 and toward the rotating shaft 11 from the first top portion 22. It is a corner formed by bending in the direction opposite to the direction and moving toward the rotating shaft 11. The second top 23 is formed so that the opening angle θ1 of the first top 22 is small, so that the inner peripheral edge 24 located on the inner peripheral side of the first top 22 faces the turbine impeller 12 of the bearing housing 14. This is to prevent contact with and interference with the surface 14b. That is, the inner peripheral edge portion 24 is provided so as not to contact the surface 14 b of the bearing housing 14 and the turbine impeller 12, and thus not to interfere with them.

Therefore, the opening angle θ <b> 2 of the second top portion 23 is appropriately set according to the opening angle θ <b> 1 of the first top portion 22. Specifically, the opening angle θ <b> 2 is set so that the inner peripheral side (of the heat shield plate 15) from the second top 23 is substantially orthogonal to the central axis of the rotating shaft 11.
Moreover, in this embodiment, the 2nd top part 23 is formed facing the level | step-difference part 16b which divides the said recessed part 16a used as the balance correction part of the said turbine impeller 12. FIG. That is, the second top portion 23 is disposed to face the stepped portion 16b or a position in the vicinity thereof.

  Further, in the present embodiment, the inner peripheral edge 24 of the heat shield 15 is on the outer peripheral surface of the step portion 25 formed in the vicinity of the turbine side opening 14 c of the surface 14 b of the bearing housing 14 facing the turbine impeller 12. Abut. As a result, the heat insulating plate 15 forms a hollow heat insulating portion 26 between the surface 14 b of the bearing housing 14 facing the turbine impeller 12.

  Under such a configuration, the heat shielding plate 15 suppresses heat from being transferred from the turbine housing 13 side, which becomes hot during operation, to the bearing housing 14 side, which becomes relatively low temperature by being cooled. It has become.

The turbine-side opening 14c is a portion of an internal hole (not shown) for housing and holding the turbine shaft 12 formed in the bearing housing 14 that is open to the turbine housing 13 side.
An annular seal ring 27 that seals between the bearing housing 14 and the end of the turbine impeller 12 (end on the turbine shaft 11 side) is inserted into the turbine-side opening 14c. Yes. This prevents foreign matters such as combustion residues that have passed between the first top 22 and the turbine impeller 12 from flowing into the bearing housing 14.

In the turbocharger 10 having such a configuration, the heat shield 15 forms the second top 23 on the inner peripheral side (of the heat shield 15) from the first top 22. Can be made smaller than the conventional apex. That is, since the second top portion 23 is formed, thereby preventing the inner peripheral edge portion 24 of the heat shield plate 15 from interfering with the bearing housing, the opening angle θ1 of the first top portion 22 should be made sufficiently small. Can do.
And by reducing the opening angle θ1 in this way, the heat shield 15 is heated during the operation of the turbocharger 10, the residual stress of the first top portion 22 is released, and the opening angle θ1 of the first top portion 11 is expanded. In addition, the inner peripheral edge 24 of the heat shield plate 15 can be prevented from contacting the turbine impeller 12. Therefore, it is possible to reliably prevent the inner peripheral edge 24 of the heat shield plate 15 from coming into contact with the turbine impeller 12.

  In addition, when the residual stress of the first top portion 22 is released by heating and the opening angle θ1 of the first top portion 22 is expanded, the residual stress is also released from the second top portion 23. θ2 is expanded. As a result, the inner peripheral edge 24 of the heat shield 15 is displaced in a direction away from the turbine impeller 12. Therefore, it is possible to more reliably prevent the inner peripheral edge 24 from coming into contact with the turbine impeller 12.

  Further, since the second top portion 23 is formed so as to face the step portion 16b that defines the concave portion 16a serving as the balance correction portion of the turbine impeller 12, the distance between the first top portion 22 and the second top portion 23 is set. Therefore, the space between the inner peripheral side (of the heat shield plate 15) and the turbine impeller 12 from the second top 23 is sufficiently secured, and the inner peripheral edge 24 comes into contact with the turbine impeller 12. This can be prevented more reliably.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the shape of the heat shield plate 15 is not limited to the shape shown in FIG. 1 and FIG. 2, and various shapes can be adopted as long as it has a first top portion and a second top portion. .

3A and 3B are side views of the main part (half part) showing a modification of the heat shield plate.
The heat shield plate 15a shown in FIG. 3 (a) is different from the heat shield plate 15 shown in FIGS. 1 and 2 in the heat shield plate 15a shown in FIG. The third top portion 28 is bent or curved toward the housing 14. By having the third top portion 28 extending in the direction away from the turbine impeller 12 as described above, when the residual stress at each top portion is released during the operation of the turbocharger 10, the inner peripheral edge portion of the heat shield plate 15a. It can prevent more reliably that 24 contacts the turbine impeller 12.

  The heat shield plate 15b shown in FIG. 3 (b) is different from the heat shield plate 15 shown in FIGS. 1 and 2 in that the second top portion 23 of the heat shield plate 15 is bent. In the heat shield plate 15b shown in FIG. 3B, the second top portion 23b is formed to be curved. By forming the second top portion 23b to be curved in this way, the sheet metal working can be facilitated as compared with the case where the second top portion 23 is formed by bending.

Moreover, about the shape of the heat insulating board 15, it can change also about the outer periphery part 21, for example.
Fig.4 (a) is a figure which shows another modification of a heat shield, and is an expanded sectional side view of an outer periphery part. The outer peripheral edge portion 21 of the heat shield plate is different from the heat shield plate 15 shown in FIGS. 1 and 2 in that a protruding strip portion 29 is formed. The ridge 29 is formed on the entire circumference along the circumferential direction of the bowl-shaped outer peripheral edge 21. 4B, the protruding portion 29 is not fastened when the outer peripheral edge portion 21 is sandwiched between the seal surface 13a of the turbine housing 13 and the mounting flange 14a of the bearing housing 14. As shown in FIG. The outer peripheral edge 21 is substantially flat. Thereby, the protrusion part 29 functions as a metal seal gasket, and prevents gas leakage from between the seal surface 13 a of the turbine housing 13 and the mounting flange 14 a of the bearing housing 14.

DESCRIPTION OF SYMBOLS 10 ... Turbocharger, 11 ... Rotary shaft, 12 ... Turbine impeller, 12a ... Back surface, 13 ... Turbine housing, 14 ... Bearing housing, 15, 15a, 15b ... Heat shield, 16 ... Turbine hub, 16a ... Recess, 16b ... Stepped portion, 21 ... outer peripheral edge portion, 22 ... first top portion, 23, 23b ... second top portion, 24 ... inner peripheral edge portion

Claims (2)

A turbine impeller provided on a rotating shaft, a turbine housing that houses the turbine impeller, a bearing housing, and an annular heat shield provided to face the back of the turbine impeller,
The heat shield plate has an outer peripheral edge portion held between the turbine housing and the bearing housing, and an inner peripheral side of the outer peripheral edge portion is bent or curved continuously toward the turbine impeller, so that the turbine impeller The first apex is formed by moving toward the direction away from the rotation axis and toward the rotation axis, and then bending or bending in the direction opposite to the bending or bending direction toward the rotation axis side. A turbocharger characterized by forming a top.   The second top portion is formed so as to face a step portion provided on the turbine impeller and defining a concave portion serving as a balance correction portion for correcting the balance of the rotating shaft. Item 1. The turbocharger according to Item 1.

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