JP2015001183A - Turbine housing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine housing enabling cooling performance required for a cooling system to be lowered.SOLUTION: A housing body 40 of a turbine housing 31 is formed of aluminum alloy, and has a groove 41 in the inner face, shaped to extend over the whole periphery of a turbine wheel and to be recessed in the direction of a rotary shaft L1 of the wheel. An inner wall member 50 is formed of stainless steel, and has a body part 51 formed into a cylindrical shape, and a folded part 52 provided at one end of the body part 51 and shaped to be folded to the outer diameter side. The inner wall member 50 is provided in the housing body 40 in such a form that the front end of the folded part 52 is fitted into the groove 41. At a low temperature, an inner face 55 of the folded part 52 comes in close contact with a face 45 on the inner diameter side of the groove 41 and a clearance is formed between an outer face 54 of the folded part 52 and a face 46 on the outer diameter side of the groove 41. At a high temperature, the outer face 54 of the folded part 52 comes in close contact with the face 46 on the outer diameter side of the groove 41.

Description

  The present invention relates to a water-cooled turbine housing.

  Conventionally, it has been proposed to form a turbine housing of a turbocharger from an aluminum alloy (see Patent Document 1). In addition, it has been proposed to form a cooling water passage for circulating cooling water for cooling the housing inside the turbine housing.

JP 2008-19711 A

  Aluminum alloys have higher thermal conductivity than iron alloys such as cast iron. Therefore, in a turbine housing formed of an aluminum alloy, the amount of heat transferred from the exhaust gas passing through the inside to the engine cooling water is likely to be larger than that of a turbine housing formed of an iron alloy. Therefore, when the turbine housing is formed of an aluminum alloy, the cooling performance required for a cooling system including a cooling water channel is increased, leading to an increase in the size of the cooling system or an increase in the flow rate of engine cooling water. There is a risk of deteriorating the fuel efficiency of the car.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a turbine housing capable of reducing the cooling performance required for the cooling system.

  A turbine housing for solving the above problems is formed of a housing body formed of an aluminum alloy and having a cooling water passage for circulating engine cooling water therein, and a material having a lower thermal conductivity than the housing body. And an inner wall member that constitutes the inner wall of the shroud portion that becomes the peripheral wall of the turbine wheel.

  According to the turbine housing, since the inner wall member constituting the inner wall of the shroud portion is formed of a material having a lower thermal conductivity than the aluminum alloy, the inner wall member is compared with the entire turbine housing formed of the aluminum alloy. It is possible to reduce the amount of heat received from the exhaust in the portion where the is disposed. As a result, the turbine housing can be maintained at an appropriate temperature by circulating a relatively small amount of cooling water through a cooling system including a cooling water channel or the like, so that the cooling performance required for the cooling system can be lowered. it can.

  In the turbine housing, the housing body and the inner wall member are made of different materials, and their thermal expansion amounts are also different. For this reason, when a cylindrical inner wall member is simply disposed inside the housing body, the surface pressure at the contact portion increases and decreases with changes in temperature. When the increase or decrease in the surface pressure is repeated, the housing body and the inner wall member are plastically deformed and the surface pressure is lowered, so that the support of the inner wall member by the housing body becomes unstable or the stress caused by the increase of the surface pressure. May cause a decrease in durability.

  In the turbine housing, the housing main body has a groove extending on the inner surface thereof over the entire circumference of the turbine wheel and recessed in the rotation axis direction of the wheel. The inner wall member has a main body portion formed in a cylindrical shape, and a folded portion that is provided at one end of the main body portion and folded back to the outer diameter side. The inner wall member is provided on the housing body in such a manner that the tip of the folded portion fits into the groove. The inner wall member has an inner surface of the folded portion that is in close contact with an inner diameter side surface on both side surfaces of the groove at a low temperature, and a gap is formed between the outer surface of the folded portion and the outer diameter side surface on both side surfaces of the groove. On the other hand, at the high temperature, the outer surface of the folded portion and the outer diameter side surfaces of the both side surfaces of the groove are in close contact with each other.

  According to the turbine housing, when the inner wall member is not so thermally expanded, the inner diameter and the outer diameter of the tip of the folded portion of the inner wall member are small. At this time, since the inner surface of the folded portion of the inner wall member is pressed against the inner diameter side surface of the groove of the housing body, the surfaces are in close contact with each other. Thereby, an inner wall member comes to be supported by the contact part of each surface. When the inner wall member becomes high temperature, the inner diameter and the outer diameter of the folded portion of the inner wall member increase with the thermal expansion. Along with this thermal expansion, although the surface pressure at the contact portion between the inner surface of the folded portion of the inner wall member and the inner surface of the groove of the housing body decreases, the outer surface of the folded portion of the inner wall member is outside the groove of the housing body. Each surface comes into close contact with the surface on the radial side. Thereby, an inner wall member comes to be supported by the contact part of such each surface.

  According to the turbine housing, although the amount of thermal expansion differs between the housing body and the inner wall member, the surface pressure of the portion that supports the inner wall member by switching the portion that mainly supports the inner wall member in the housing body according to the thermal expansion. Can be kept high. Therefore, it is possible to suppress instability of the support of the inner wall member by the housing main body due to the temperature change. In addition, since the portion that mainly supports the inner wall member in the housing main body is switched in accordance with the thermal expansion, it is possible to prevent the surface pressure of a specific surface from becoming unnecessarily high with a temperature change. It is also possible to suppress a decrease in durability performance.

  In the turbine housing, it is preferable that the inner wall member is provided in such a manner that the main body is separated from the housing main body at a low temperature and the main body is in contact with the housing main body by deformation due to thermal expansion at a high temperature.

  In the turbine housing, when the inner wall member is at a low temperature, a gap can be formed between the outer surface of the main body portion of the inner wall member and the inner surface of the housing main body, or the formation range of the gap can be increased. Since this gap functions as a heat insulating layer, the amount of heat transfer from the exhaust to the housing body can be reduced by forming the gap or increasing the formation range of the gap. Thereby, the cooling performance requested | required of a cooling system at this time can be made low.

  Moreover, when the inner wall member is at a high temperature, the range in which the gap is formed between the outer surface of the main body portion of the inner wall member and the inner surface of the housing main body can be reduced due to deformation due to thermal expansion. As a result, the amount of heat transfer from the exhaust to the housing body can be increased, so that the degree of cooling by the cooling system can be increased to suppress an increase in the temperature of the inner wall member or to reduce the exhaust temperature.

The said turbine housing WHEREIN: It is preferable to form a recessed part in the outer surface of the said main-body part in the said inner wall member.
By forming the concave portion on the outer surface of the inner wall member, it is possible to form a fragile portion in a specific portion of the inner wall member as compared with other portions. According to the turbine housing, by forming such a recess, it is possible to set a portion that is easily deformed when the inner wall member is deformed due to thermal expansion. Therefore, the deformation mode of the inner wall member can be easily controlled in a desired mode. It becomes possible.

The said turbine housing WHEREIN: The said recessed part can be formed in the outer surface of the said main body part in the said inner wall member over the perimeter direction.
According to the turbine housing, at least a part of the inner wall member can be uniformly deformed toward the outer diameter side over the entire circumference in the circumferential direction.

1 is a cross-sectional view schematically showing a cross-sectional structure of a turbocharger to which a turbine housing according to a first embodiment is applied. Sectional drawing which shows the cross-section of the turbine housing of 1st Embodiment. The perspective view which shows the perspective structure of the inner wall member of the turbine housing. Sectional drawing which expands and shows the cross-section of the inner wall member of the turbine housing, and its periphery. The graph which shows transition of the difference of the internal diameter of the folding | turning part accompanying the temperature change, and the diameter of the surface of the inner diameter side of a groove | channel, and the transition of the difference of the outer diameter of the same folding | turning part, and the diameter of the surface of the outer diameter side of a groove | channel. Sectional drawing which expands and shows the cross-section of the inner wall member and its periphery at the time of low temperature. Sectional drawing which expands and shows an example of the cross-sectional structure of the inner wall member in the temperature rise process, and its periphery. Sectional drawing which expands and shows the cross-section of the inner wall member and its periphery at the time of high temperature. The perspective view which shows the perspective structure of the inner wall member of the turbine housing of 2nd Embodiment. Sectional drawing which expands and shows the cross-section of the inner wall member of the turbine housing, and its periphery. Sectional drawing which expands and shows the cross-section of the inner wall member and its periphery at the time of high temperature.

(First embodiment)
Hereinafter, a first embodiment of the turbine housing will be described.
As shown in FIG. 1, the turbocharger 10 includes a compressor 20 disposed in the intake passage 2 of the internal combustion engine 1, a turbine 30 disposed in the exhaust passage 3 of the internal combustion engine 1, the compressor 20 and the turbine. And a center housing 11 for connecting 30.

  A compressor chamber 22 is formed inside the compressor housing 21, and a compressor wheel 23 is accommodated in the compressor chamber 22. On the other hand, a turbine chamber 32 is formed inside the turbine housing 31, and a turbine wheel 33 is accommodated in the turbine chamber 32. On the other hand, a shaft 12 is rotatably supported by the center housing 11, a compressor wheel 23 is fixed to one end of the shaft 12, and a turbine wheel 33 is fixed to the other end. The turbocharger 10 has a structure in which the compressor wheel 23 and the turbine wheel 33 rotate integrally.

  The compressor chamber 22 extends along the rotation axis L <b> 1 of the compressor wheel 23. The compressor housing 21 is formed with a scroll passage 24 extending in a spiral shape on the outer periphery of the compressor wheel 23.

  On the other hand, the turbine chamber 32 extends along the rotation axis L <b> 1 of the turbine wheel 33. The turbine housing 31 is formed with a scroll passage 34 extending in a spiral shape on the outer periphery of the turbine wheel 33. The scroll passage 34 is opened in an annular shape over the entire circumference of the peripheral wall of the turbine chamber 32.

  The turbocharger 10 supercharges the internal combustion engine 1 as follows. When the exhaust gas of the internal combustion engine 1 is blown onto the turbine wheel 33 through the scroll passage 34, the turbine wheel 33 rotates by receiving the energy of the exhaust flow. Then, the rotation of the turbine wheel 33 is transmitted to the compressor wheel 23 through the shaft 12, and the compressor wheel 23 rotates. Thus, in the compressor 20, the intake air flowing into the compressor chamber 22 from the inlet portion 20 a of the compressor 20 is sent to the scroll passage 24 and eventually to each cylinder of the internal combustion engine 1 due to the action of centrifugal force caused by the rotation of the compressor wheel 23. . In the internal combustion engine 1, the output can be improved by performing supercharging using the energy of the exhaust.

  In the turbocharger 10, the housing body 40 of the turbine housing 31 is formed of an aluminum alloy. The turbocharger 10 is a water-cooled type. Specifically, a cooling water channel 35 for circulating the cooling water is formed inside the housing body 40. The turbine housing 31 is cooled by forcibly circulating the cooling water inside the cooling water passage 35. In the present embodiment, a part of the cooling water used for cooling the internal combustion engine 1 during operation of the internal combustion engine 1 is supplied to the cooling water passage 35 and circulated.

  As shown in FIG. 1 or FIG. 2, the turbine housing 31 includes a housing body 40 and an inner wall member 50 attached to the inside of the housing body 40. The inner wall member 50 is made of a material having high heat resistance and higher thermal conductivity than the housing body 40 (in this embodiment, stainless steel). Further, the inner wall member 50 is formed in a cylindrical shape in which one end (left side in FIG. 1) is folded to the outer diameter side.

  The inner wall member 50 includes an entire portion of the turbine chamber 32 on the downstream side in the exhaust flow direction from the turbine wheel 33, a portion that becomes a peripheral wall of the turbine wheel 33 (so-called shroud portion), and the scroll passage 34 on the turbine wheel 33 side. It is attached to the inside of the housing main body 40 so as to form the inner wall of this part. In addition, the inner wall member 50 is disposed in a state in which a portion on the side folded to the outer diameter side forms an inner wall of the shroud portion and the scroll passage 34.

  In the turbine housing 31, the inner wall member 50 constituting a part of the inner wall of the passage (including the shroud portion) through which the exhaust passes is formed of a material having a lower thermal conductivity than the aluminum alloy. Therefore, the amount of heat received from the exhaust at the portion where the inner wall member 50 is disposed can be reduced as compared with the case where the entire turbine housing is formed of an aluminum alloy. Thereby, since the turbine housing 31 can be maintained at an appropriate temperature by circulating a relatively small amount of cooling water through the cooling system including the cooling water channel 35 and the like, the cooling performance required for the cooling system is lowered. be able to.

  Here, in the said turbine housing 31, the material of the housing main body 40 and the inner wall member 50 differs, and those thermal expansion amounts also differ. For this reason, when a cylindrical inner wall member is simply disposed inside the housing body, the surface pressure at the contact portion increases or decreases with changes in temperature. When the increase or decrease in the surface pressure is repeated, the housing body and the inner wall member are plastically deformed and the surface pressure is lowered, so that the support of the inner wall member by the housing body becomes unstable or the stress caused by the increase of the surface pressure. May cause a decrease in durability.

In order to avoid such inconvenience, in the present embodiment, the inner wall member 50 is disposed inside the housing body 40 as follows.
As shown in FIG. 3, the inner wall member 50 is integrally formed at one end portion of the main body 51 formed in a cylindrical shape with the same outer diameter and folded back to the outer diameter side. And a folded portion 52 having a shape. The folded portion 52 is formed in a shape extending in the direction of the rotation axis L <b> 1 of the turbine wheel 33 at a position spaced from the outer peripheral surface 53 of the main body portion 51.

  As shown in FIG. 2, in the turbine housing 31, the end portion of the inner wall member 50 where the folded portion 52 is formed forms the shroud portion and the inner wall of the scroll passage 34. The housing main body 40 has a shape that extends over the entire circumference of the turbine wheel 33 (see FIG. 1) on the inner surface thereof at a position corresponding to the scroll passage 34, and a shape that is recessed in the direction of the rotation axis L1 of the turbine wheel 33. The groove 41 is formed. The groove 41 is formed at a position corresponding to the end of the inner wall member 50 on the scroll passage 34 side, that is, the folded portion 52 of the inner wall member 50.

  Moreover, the part corresponding to the turbine chamber 32 of the housing main body 40 is formed in a shape in which the inner surface 43 extends in a circular cross section. A stepped portion 44 is formed at the end of the inner surface 43 of the housing body 40 on the folded portion 52 side so as to protrude inward as compared with the downstream portion (the right side in the drawing) in the exhaust flow direction. Has been. The step 44 extends in an annular shape over the entire circumference of the turbine wheel 33 (see FIG. 1). Further, a portion of the inner surface 43 of the housing main body 40 on the downstream side in the exhaust flow direction from the stepped portion 44 is formed in a shape in which the diameter of the inner surface 43 is the same.

  As shown in FIG. 4, in the turbine housing 31, the inner wall member 50 is attached to the housing body 40 such that the tip of the folded portion 52 of the inner wall member 50 fits into the groove 41 of the housing body 40. The folded portion 52 of the inner wall member 50 and the groove 41 of the housing main body 40 are such that the inner diameter of the folded portion 52 is slightly larger than the diameter of the surface 45 on the inner diameter side of the groove 41 when the turbine housing 31 is left at room temperature. The outer diameter of the folded portion 52 is formed to be slightly smaller (for example, several tens of micrometers) than the diameter of the surface 46 on the outer diameter side of the groove 41. Further, in the turbine housing 31, the inner wall member 50 is attached to the housing main body 40 in such a manner that the outer peripheral surface 53 of the main body 51 of the inner wall member 50 is separated from the inner surface 43 of the portion corresponding to the turbine chamber 32 of the housing main body 40 at low temperatures. It has been. The inner wall member 50 is attached to the housing main body 40 by inserting the inner wall member 50 into the housing main body 40 from the center housing 11 side.

Hereinafter, the operation of the inner wall member 50 disposed in the housing body 40 in this manner will be described with reference to FIGS.
FIG. 5 shows a change in the difference (= DA−DB) between the inner diameter DA of the turned-up portion 52 of the inner wall member 50 and the diameter DB of the inner surface 45 on both side surfaces of the groove 41 as the temperature of the turbine housing 31 changes. And the transition of the difference (= DC−DD) between the outer diameter DC of the folded portion 52 and the diameter DD of the outer surface 46 on both side surfaces of the groove 41. 6 shows the relationship between the relative positions of the housing body 40 and the inner wall member 50 at a low temperature, FIG. 7 shows the same relationship in the temperature rising process, and FIG. 8 shows the same relationship at a high temperature. The broken line in FIGS. 6-8 has shown the external shape of the folding | returning part 52 when it is assumed that the temperature of the inner wall member 50 was raised alone. 6 and 8, the gap between the folded portion 52 of the inner wall member 50 and the groove 41 of the housing body 40 is exaggerated for easy understanding, but the actual gap is very small. 6 to 8, the width where the folded portion 52 of the inner wall member 50 and the groove 41 of the housing body 40 overlap is exaggerated for easy understanding, but the actual overlapping width is very small.

  When the temperature of the turbine housing 31 is low and the inner wall member 50 is not so thermally expanded, such as immediately after the operation of the internal combustion engine 1 is started, both the inner diameter and the outer diameter of the folded portion 52 of the inner wall member 50 are small.

  As is clear from FIG. 5, the inner diameter DA of the folded portion 52 is slightly smaller than the diameter DB of the inner surface 45 of the groove 41 at this time. Therefore, as shown in FIG. 6, the inner surface 55 of the folded portion 52 of the inner wall member 50 is pressed against the inner surface 45 of the groove 41 of the housing body 40, and the surfaces 45 and 55 are in close contact with each other. Become. Therefore, the inner wall member 50 is supported in the housing body 40 by the contact portions of the surfaces 45 and 55.

  Also, as is apparent from FIG. 5, when the housing body 40 is at a low temperature, the outer diameter DC of the folded portion 52 is slightly smaller than the diameter DD of the outer surface 46 of the groove 41. Therefore, as shown in FIG. 6, a gap is formed between the outer surface 54 of the folded portion 52 of the inner wall member 50 and the outer diameter side surface 46 of the groove 41 of the housing body 40, and the contact portion between these surfaces 46, 54. The surface pressure is extremely low, and the surfaces 46 and 54 are not in close contact with each other.

  When the temperature of the turbine housing 31 rises due to continued operation of the internal combustion engine 1, etc., the diameter of the inner surface 45 and the outer surface 46 of the groove 41 of the housing body 40 gradually increase accordingly. As the diameter increases, the inner diameter and outer diameter of the folded portion 52 of the inner wall member 50 gradually increase.

  In the turbine housing 31, the housing body 40 formed of an aluminum alloy having high thermal conductivity is directly cooled by cooling water passing through the cooling water passage 35, whereas it is formed of stainless steel having low thermal conductivity. The inner wall member 50 is cooled via the housing body 40. Therefore, the temperature of the inner wall member 50 is higher than the temperature of the housing main body 40, and the thermal expansion amount of the inner wall member 50 is larger than the thermal expansion amount of the housing main body 40. Therefore, in the turbine housing 31, when the temperature of the housing main body 40 rises, the inner surface 45 and the outer diameter of the groove 41 of the housing main body 40 are compared with the amount of expansion of the inner diameter and outer diameter of the folded portion 52 of the inner wall member 50. The amount of enlargement of the side surface 46 is reduced.

  As shown in FIG. 5, in the process of increasing the temperature of the turbine housing 31, the difference between the inner diameter DA of the folded portion 52 of the inner wall member 50 and the diameter DB of the inner surface 45 on both sides of the groove 41 (= DA−DB) gradually increases, and the difference (= DD−DC) between the diameter DD of the outer diameter side surface 46 on both side surfaces of the groove 41 and the outer diameter DC of the folded portion 52 gradually decreases. Therefore, the contact pressure between the inner surface 55 of the folded portion 52 and the inner surface 45 of the groove 41 gradually decreases at this time, while the outer surface 54 of the folded portion 52 and the outer diameter of the groove 41 are gradually decreased. As the gap with the side surface 46 becomes smaller, the surfaces 46 and 54 come into contact with each other. In the course of the temperature rise of the turbine housing 31, if the surface pressures of these contact portions become substantially equal, the difference between the inner diameter DA of the folded portion 52 and the diameter DB of the inner surface 45 on both sides of the groove 41 (= DA −DB), and the difference (= DD−DC) between the diameter DD of the outer diameter side surface 46 and the outer diameter DC of the folded portion 52 on both side surfaces of the groove 41 are negative values.

  As shown in FIG. 7, at this time, the inner surface 55 of the folded portion 52 is pressed against the inner surface 45 of the groove 41, and the contact pressure between the surfaces 45 and 55 is moderately high. At the same time, the outer surface 54 of the folded portion 52 is pressed against the surface 46 on the outer diameter side of the groove 41, and the contact pressure between the surfaces 46 and 54 is appropriately high. Therefore, the inner wall member 50 comes to be supported by these contact portions.

  As shown in FIG. 5, when the inner wall member 50 of the turbine housing 31 is further heated, for example, when the operation of the internal combustion engine 1 is continued at a high exhaust temperature, the inner diameter DA of the folded portion 52 of the inner wall member 50 The difference (= DA-DB) between the diameter DB of the inner surface 45 on both side surfaces of the groove 41 becomes a positive value. On the other hand, the difference (= DD−DC) between the diameter DD of the outer diameter side surface 46 on both side surfaces of the groove 41 and the outer diameter DC of the folded portion 52 is further reduced.

  As shown in FIG. 8, at this time, a gap is formed between the inner surface 55 of the folded portion 52 and the inner surface 45 of the groove 41, and the contact pressure between the contact surfaces of these surfaces 45 and 55 becomes extremely small. On the other hand, the surface pressure of the contact portion between the outer surface 54 of the folded portion 52 and the outer diameter side surface 46 of the groove 41 becomes sufficiently high. That is, although the surface pressure at the contact portion between the inner surface 55 of the folded portion 52 of the inner wall member 50 and the inner surface 45 of the groove 41 of the housing body 40 decreases with thermal expansion, the outer surface 54 of the folded portion 52 is reduced. The surfaces 46 and 54 come into close contact with each other when pressed against the outer diameter side surface 46 of the groove 41. Accordingly, at this time, the inner wall member 50 is supported by the close contact portion between the outer surface 54 of the folded portion 52 and the outer surface 46 of the groove 41.

  In the turbine housing 31, the outer wall surface 53 of the main body 51 of the inner wall member 50 is separated from the inner surface 43 of the portion corresponding to the turbine chamber 32 of the housing main body 40 at a low temperature. It is attached. Therefore, a gap is formed between the inner wall member 50 and the housing body 40 at a low temperature. Even when the temperature of the turbine housing 31 rises, the outer peripheral surface 53 of the main body 51 of the inner wall member 50 is pressed against the protruding end of the step 44 of the inner surface 43 of the housing main body 40 by thermal expansion. However, a gap is formed between the surfaces 43 and 53 in a portion other than the portion where the stepped portion 44 is formed on the surface facing the outer peripheral surface 53 of the main body 51 and the inner surface 43 of the housing main body 40. The Since such a gap functions as a heat insulating layer, the amount of heat transfer from the exhaust to the housing body 40 can be reduced by forming the gap. Thereby, the cooling performance requested | required of the said cooling system can be made low.

  In the turbine housing 31, although the relative position between the housing body 40 and the inner wall member 50 changes because the amount of thermal expansion of the housing body 40 and the amount of thermal expansion of the inner wall member 50 due to the temperature rise vary, Accordingly, the portion of the housing body 40 that mainly supports the inner wall member 50 is switched. Thereby, the surface pressure of the part which supports the inner wall member 50 can be kept high. Therefore, the inner wall member 50 can be properly supported by the housing main body 40 without being affected by the temperature change of the turbine housing 31, and destabilization of the support of the inner wall member 50 by the housing main body 40 due to the temperature change can be suppressed. it can.

  Moreover, in the turbine housing 31, there is a gap between the outer surface 54 of the folded portion 52 and the outer surface 46 of the groove 41 when the relative position of the housing body 40 and the inner wall member 50 changes due to thermal expansion. The state (state shown in FIG. 6) shifts to a state (state shown in FIG. 8) where there is a gap between the inner surface 55 of the folded portion 52 and the inner surface 45 of the groove 41.

  As a result, when the folded portion 52 approaches the inner diameter side surface 46 of the groove 41 when the relative position between the folded portion 52 and the groove 41 is changed due to the temperature change, until the gap becomes “0”. Does not increase the contact pressure. Therefore, the increase in the surface pressure between the inner surface 55 of the folded portion 52 and the inner diameter side surface 45 of the groove 41 and the increase in the surface pressure between the outer surface 54 of the folded portion 52 and the outer surface 46 of the groove 41 are suppressed accordingly. be able to. Therefore, it is possible to suppress the surface pressure of the contact portion between the folded portion 52 of the inner wall member 50 and the groove 41 of the housing main body 40 from becoming unnecessarily high, and it is possible to suppress a decrease in the durability performance of the turbine housing 31.

As described above, according to the present embodiment, the following effects can be obtained.
(1) A groove 41 having a shape extending over the entire circumference of the turbine wheel 33 and recessed in the direction of the rotation axis L1 of the turbine wheel 33 is formed on the inner surface of the housing main body 40, and the inner wall member 50 is formed into a cylindrical main body. It was formed in a shape having a portion 51 and a folded portion 52 provided at one end of the main body portion 51 and folded to the outer diameter side. And the inner wall member 50 was provided in the housing main body 40 in the aspect which the front-end | tip of the said folding | returning part 52 fits into the said groove | channel 41. FIG. At a low temperature, the inner surface 55 of the folded portion 52 and the inner surface 45 of the groove 41 are in close contact, and a gap is formed between the outer surface 54 of the folded portion 52 and the outer surface 46 of the groove 41. On the other hand, when the temperature is high, the outer surface 54 of the folded portion 52 and the outer surface 46 of the groove 41 are in close contact with each other. Therefore, it is possible to suppress instability of the support of the inner wall member 50 by the housing body 40 due to the temperature change of the turbine housing 31. In addition, it is possible to suppress the surface pressure of the contact portion between the folded portion 52 of the inner wall member 50 and the groove 41 of the housing main body 40 from becoming unnecessarily high, and to suppress a decrease in the durability performance of the turbine housing 31.

(Second Embodiment)
Hereinafter, a second embodiment of the turbine housing will be described focusing on differences from the first embodiment.

  The turbine housing of this embodiment and the turbine housing of the first embodiment differ only in the shape of the portion corresponding to the turbine chamber of the housing main body and the shape of the main body portion of the inner wall member. In addition, since it is the same structure as 1st Embodiment about the part other than the main-body part of an inner wall member and the part corresponding to the turbine chamber of a housing main body, while attaching the same code | symbol about the same part, it shows that I will omit the detailed explanation.

Hereinafter, the shape of the housing main body and the inner wall member of the turbine housing of the present embodiment will be described.
As shown in FIG. 9, the inner wall member 70 has a main body portion 71 formed in a cylindrical shape having the same outer diameter, and a shape formed integrally with one end portion of the main body portion 71 and folded to the outer diameter side. And a folded portion 52. Further, a concave portion 76 having an annular shape extending over the entire circumference in the circumferential direction is formed on the outer peripheral surface 73 of the main body portion 71.

  As shown in FIG. 10, a portion of the housing body 80 corresponding to the turbine chamber 32 is formed in a shape in which an inner surface 83 extends in a circular cross section. A stepped portion 44 is formed at the end of the inner surface 83 of the housing body 80 on the folded-back portion 52 side so as to protrude inward as compared with the downstream portion in the exhaust flow direction (right side in the drawing). ing. In addition, a tapered portion 87 having a tapered shape in which the diameter of the inner surface 43 increases toward the downstream side is formed in a portion of the inner surface 83 of the housing body 80 on the downstream side of the stepped portion 44 in the exhaust flow direction.

  In the turbine housing 61 of the present embodiment, the concave portion 76 of the inner wall member 70 is located on the downstream side (right side in the drawing) in the exhaust flow direction from the portion facing the step portion 44 of the housing body 80, and at the step portion 44. It is formed at a position close to the facing part.

Hereinafter, the operation by forming the housing body 80 and the inner wall member 70 in such a shape will be described with reference to FIG.
In the turbine housing 61, the outer peripheral surface 73 of the main body 71 of the inner wall member 70 is separated from the inner surface 83 of the housing main body 80 at a low temperature. Therefore, a gap is formed between the outer peripheral surface 73 of the main body 71 of the inner wall member 70 and the inner surface 83 of the housing main body 80 at a low temperature. Since this gap functions as a heat insulating layer, the amount of heat transferred from the exhaust to the housing body 80 can be reduced by forming the gap. As a result, the cooling performance required for the cooling system can be lowered. In addition, since the decrease in the exhaust temperature can be suppressed, the catalyst can be warmed up early.

  When the temperature of the turbine housing 61 rises, for example, when the operation of the internal combustion engine 1 is continued, the portion of the outer peripheral surface 73 of the main body 71 facing the step 44 is the same due to the thermal expansion of the inner wall member 70. It will be in the state pressed against the protrusion of the step part 44. FIG. As a result, the portion of the outer peripheral surface 73 of the inner wall member 70 that is in contact with the protruding end of the step 44 is restricted from being deformed to the outer diameter side of the inner wall member 70.

  When the temperature of the turbine housing 61 further rises, the portion of the inner wall member 70 on the downstream side in the exhaust flow direction from the portion facing the stepped portion 44 is further deformed to the outer diameter side due to thermal expansion. A portion of the main body 71 of the inner wall member 70 where the concave portion 76 is formed has a lower strength than the other portions of the main body 71. Therefore, at this time, the portion where the recess 76 is formed bends more than the other portions. As a result, the portion of the inner wall member 70 on the downstream side in the exhaust flow direction from the portion where the recess 76 is formed is deformed into a tapered shape having a larger inner diameter toward the downstream side.

  As a result, as shown in FIG. 11, the portion facing the step 44 of the housing body 80 on the outer peripheral surface 73 of the inner wall member 70 is in contact with the protruding end of the step 44 at a high temperature. Nearly the entire portion on the downstream side in the exhaust flow direction from the portion facing the stepped portion 44 is in contact with the inner surface 83 of the housing body 80. As described above, at a high temperature, the range in which the gap is formed between the outer peripheral surface 73 of the main body 71 of the inner wall member 70 and the inner surface 43 of the housing main body 80 due to deformation due to thermal expansion of the inner wall member 70 is extremely small. can do. As a result, the amount of heat transferred from the exhaust to the housing main body 80 can be increased. Therefore, the degree of cooling by the cooling system is increased to suppress the temperature rise of the inner wall member 70, or the exhaust temperature is decreased to purify the exhaust. The thermal deterioration of the catalyst can be suppressed.

  In the turbine housing 61, by forming the recess 76 in the outer peripheral surface 73 of the main body 71 of the inner wall member 70, it is possible to form a fragile portion in a specific portion of the inner wall member 70 as compared with other portions. it can. Therefore, it is possible to set a portion that is easily deformed when the inner wall member 70 is deformed due to thermal expansion, and it is possible to easily control the deformation mode of the inner wall member 70 in a desired manner. Further, since the recess 76 is formed in an annular shape over the entire circumference in the circumferential direction of the outer peripheral surface 73 of the inner wall member 70, a part of the inner wall member 70 is directed toward the outer diameter side over the entire circumference in the circumferential direction. Can be evenly deformed.

As described above, according to the present embodiment, the effects described in the following (2) to (4) can be obtained in addition to the effects described in (1) above.
(2) Since the outer peripheral surface 73 of the main body 71 of the inner wall member 70 is separated from the inner surface 43 of the housing main body 80 at a low temperature, the cooling performance required for the cooling system can be lowered. In addition, when the temperature is high, the portion of the outer peripheral surface 73 of the inner wall member 70 that faces the step 44 of the housing body 80 is in contact with the protruding end of the step 44 and the portion that faces the step 44. Nearly the entire portion on the downstream side in the exhaust flow direction comes into contact with the inner surface 83 of the housing body 80. Thereby, the degree of cooling by the cooling system can be increased, and the temperature rise of the inner wall member 70 can be suppressed, or the exhaust temperature can be lowered.

  (3) By forming the recess 76 in the outer peripheral surface 73 of the inner wall member 70, a specific portion of the inner wall member 70 can be formed with a weaker portion than other portions. During deformation due to thermal expansion, the deformation mode of the inner wall member 70 can be easily controlled in a desired mode.

  (4) Since the recess 76 is formed in an annular shape extending over the entire circumference in the circumferential direction of the outer peripheral surface 73 of the inner wall member 70, a part of the inner wall member 70 is evenly directed toward the outer diameter over the entire circumference in the circumferential direction. Can be transformed into

(Other embodiments)
Each of the above embodiments may be modified as follows.
In the first embodiment, the step 44 of the housing body 40 may be omitted. That is, the entire inner surface 43 of the portion corresponding to the turbine chamber 32 of the housing main body 40 may be formed in a shape extending in a circular cross section having the same inner diameter.

  In the second embodiment, the step portion 44 of the housing body 80 may be omitted. That is, the entire inner surface 43 of the portion corresponding to the turbine chamber 32 of the housing body 80 may be formed in a shape in which the inner diameter of the cross section gradually increases toward the downstream side in the exhaust flow direction.

  -In 2nd Embodiment, instead of forming the recessed part 76 of the inner wall member 70 in a ring shape, you may form in the outer surface of the main-body part of an inner wall member in the shape extended intermittently over the perimeter direction. .

  -In 2nd Embodiment, the formation position of the recessed part 76 in the outer peripheral surface 73 of the main-body part 71 of the inner wall member 70 can be changed arbitrarily. Specifically, the concave portion can be formed at a position adjacent to a portion facing the step portion 44 of the housing main body 80, or a portion can be formed at a position overlapping with a portion facing the step portion 44. . The point is that the concave portion 76 can be formed on the outer peripheral surface 73 of the main body 71 of the inner wall member 70 as long as it is a specific portion that is separated from the housing main body 80 at a low temperature. Even with such a configuration, when the inner wall member 70 is deformed by thermal expansion, the deformation mode of the inner wall member 70 can be easily controlled in a desired manner.

  In the second embodiment, the portion corresponding to the turbine chamber 32 of the housing body 80 is not limited to be formed in a tapered shape in which the inner diameter increases toward the downstream side in the exhaust flow direction, and extends with the same inner diameter. It may be formed into a shape, may be formed into a shape with a partially reduced inner diameter, or may be formed into a shape other than a circular cross-section with a partially protruding convex portion. According to such a configuration, it is possible to increase the formation range of the gap between the outer peripheral surface 73 of the main body 71 of the inner wall member 70 and the inner surface of the housing main body 80 when the inner wall member 70 is at a low temperature. The amount of heat transfer to 80 can be reduced. Moreover, the range in which the gap is formed between the outer peripheral surface 73 of the main body 71 of the inner wall member 70 and the inner surface 43 of the housing main body 80 can be reduced by deformation due to thermal expansion of the inner wall member 70 at high temperatures. . Thereby, the amount of heat transfer from the exhaust to the housing body 80 can be increased.

  In each embodiment, even when the inner wall members 50 and 70 are at a high temperature, the inner surface 55 of the folded portion 52 of the inner wall members 50 and 70 and the inner surface 46 of the groove 41 of the housing body 40 A structure in which no gap is formed between them may be adopted. Even in such a configuration, the surface pressure of the contact portion between the inner surface 55 of the folded portion 52 and the inner surface 46 of the groove 41 decreases due to the temperature rise of the inner wall members 50 and 70, and thus the operational effects of the above embodiments. The effect according to can be obtained.

  -In each embodiment, the inner wall members 50 and 70 are formed in the shape which comprises only the inner wall of the shroud part of the turbine housings 31 and 61 and the inner wall of the part by the side of the turbine wheel 33 of the scroll channel | path 34, or the inner wall of a shroud part It may be formed in a shape that constitutes only.

  -In each embodiment, not only forming the main-body parts 51 and 71 of the inner wall members 50 and 70 in a cylindrical shape, but forming the outer surface of the main-body parts 51 and 71 into a polygonal cross-section, A convex portion extending in the direction of the rotation axis L1 may be formed on the outer surface. In short, as long as the inner surface of the main body has a cylindrical shape extending in a circular cross section, the shape of the main body of the inner wall member can be changed to an arbitrary shape.

  In each embodiment, the inner wall members 50 and 70 may be formed of an iron alloy such as cast iron or a ceramic material instead of being formed of stainless steel. In short, any material can be used as the material for forming the inner wall members 50 and 70 as long as the material has a lower thermal conductivity than the aluminum alloy.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine, 2 ... Intake passage, 3 ... Exhaust passage, 10 ... Turbocharger, 11 ... Center housing, 12 ... Shaft, 20 ... Compressor, 20a ... Inlet part, 21 ... Compressor housing, 22 ... Compressor chamber, 23 ... Compressor wheel, 24 ... scroll passage, 30 ... turbine, 31, 61 ... turbine housing, 32 ... turbine chamber, 33 ... turbine wheel, 34 ... scroll passage, 35 ... cooling water passage, 40, 80 ... housing body, 41 ... groove, 43, 83 ... inner surface, 44 ... stepped portion, 45 ... inner diameter side surface, 46 ... outer diameter side surface, 50, 70 ... inner wall member, 51, 71 ... main body portion, 52 ... folded portion, 53, 73 ... outer periphery Surface 54, outer surface, 55 inner surface, 76 concave portion, 87 taper portion.

Claims (4)

A housing body formed of an aluminum alloy and having a cooling water passage for circulating engine cooling water therein, and a shroud portion formed of a material having a lower thermal conductivity than the housing body and serving as a peripheral wall of the turbine wheel An inner wall member constituting the inner wall of
The housing body has a groove having a shape extending over the entire circumference of the turbine wheel on the inner surface thereof and recessed in the rotational axis direction of the wheel,
The inner wall member is
A main body portion formed in a cylindrical shape and a folded portion provided in one end of the main body portion and folded back to the outer diameter side;
The front end of the folded portion is fitted into the groove, and the inner surface of the folded portion and the inner surface of both sides of the groove are in close contact with each other at low temperatures, and the outer surface of the folded portion and the groove In an aspect in which a gap is formed between the outer diameter side surfaces of the both side surfaces, and the outer surface of the folded portion and the outer diameter side surfaces of the both side surfaces of the groove are in close contact with each other at a high temperature, A turbine housing provided in the housing body. The turbine housing according to claim 1,
The turbine housing according to claim 1, wherein the inner wall member is provided in such a manner that the main body portion is separated from the housing main body at a low temperature and the main body portion is in contact with the housing main body by deformation due to thermal expansion at a high temperature. The turbine housing according to claim 2,
A turbine housing, wherein a concave portion is formed on an outer surface of the main body portion of the inner wall member. The turbine housing according to claim 3, wherein
The turbine housing, wherein the concave portion is formed on the outer surface of the main body portion of the inner wall member over the entire circumference.