JP2014118867A - Turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the shield property and thermal responsiveness of a turbine housing.SOLUTION: A turbocharger comprises a scroll part 16 of a spiral shape forming swirl flow of exhaust gas flow G inside a turbine housing 14, a turbine wheel 15 housed inside the turbine housing 14 and rotated by the exhaust gas flow G, a shroud part 18 forming an inner circumferential part of the turbine housing 14, a heat receiving part 31 of a plate-like shape constituting the shroud part 18 and provided in the vicinity of a rotor blade outer peripheral part of the turbine wheel 15 with a slight clearance C in between, and an exhaust gas introducing part 32 for introducing the exhaust gas flow G inside the scroll part 16 to a back face part of the heat receiving part 31 so as to heat the heat receiving part 31 from the back face part.

Description

  The present invention relates to a turbocharger that rotates a turbine wheel by swirling exhaust gas into a turbine housing, and more particularly, to a turbocharger that can improve shielding performance and thermal response of the turbine housing.

  In an exhaust turbocharger used in an automobile internal combustion engine or the like, an exhaust gas flow exhausted from a combustion chamber is swirled in a scroll portion of a turbine housing, and then a turbine wheel accommodated in the turbine housing is caused by the gas flow. It is rotated and discharged to the downstream side of the turbine hole. Therefore, the turbine housing and the turbine wheel accommodated therein are heated to a high temperature by the exhaust gas flow.

JP 2011-252439 A JP 2011-153623 A

By the way, the turbine housing is generally formed thick by casting. By setting the thickness to be thick, the rigidity of the turbine housing is increased, and the shielding property (containment property) that prevents damaged internal parts from jumping out to the outside. ) Is secured.
On the other hand, by adopting a thick-walled turbine housing, the heat capacity of the turbine housing may be larger than the heat capacity of the turbine wheel rotating inside, and a small clearance (chip) is formed at the outer peripheral edge of the rotor blade part of the turbine wheel. The shroud portion approaching through the clearance) is thermally deformed later than the turbine wheel.
Specifically, when a high-temperature exhaust gas flow passes through the turbine housing, the turbine wheel and the outer shroud portion of the turbine wheel undergo thermal deformation that tends to spread outward.
In general, the blade thickness of the rotor blade part of the turbine wheel is composed of parts of 1 to 2 mm, whereas the shroud part forming the inner peripheral part of the turbine housing has a thickness of 10 mm or more. The heat capacity of the shroud portion becomes larger than the heat capacity of the turbine wheel. Therefore, when a high-temperature exhaust gas flow passes through the turbine housing, the turbine wheel having a small heat capacity rises in temperature before the shroud portion having a large heat capacity and tends to spread outward, and is appropriately set in advance. It is expected that the initial rearrangement will be narrowed and the risk of contact will increase.

  In the future, the exhaust gas temperature will increase from 850 ° C. to 1000 ° C. in order to cope with higher engine output and higher responsiveness, so the risk of thermal deformation and breakage will increase. There is an urgent need to deal with the risk of thermal deformation and damage. In addition, the turbocharger is required to start immediately after the accelerator is depressed in accordance with the performance requirements of the turbocharger, and the risk of transient thermal deformation and damage due to the start-up of the turbo is increased in a short time. Accordingly, the turbine housing is required to have quick thermal response while ensuring shielding.

In addition, adopting a double wall structure in which a space portion is separated from each other as in Patent Document 2 in order to reduce the thickness of the turbine housing has a problem of increasing the weight of the turbine housing and complicating the structure.
Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a turbocharger excellent in shielding performance and thermal response of a turbine housing.

In order to solve the above-described problems, the present invention provides a spiral scroll portion that forms a swirling flow of an exhaust gas flow in a turbine housing, a turbine wheel that is housed in the turbine housing and rotates by the exhaust gas flow, and the turbine A shroud portion that forms an inner peripheral portion of the housing, a plate-shaped heat receiving member that constitutes the shroud portion and is provided close to the outer peripheral edge of the moving blade of the turbine wheel with a small clearance therebetween, and An exhaust gas flow introduction section that introduces the exhaust gas flow in the scroll section and heats the heat receiving body from the back surface section is provided on a back surface section.
According to this configuration, the surface portion on the turbine wheel side of the plate-shaped heat receiving body is heated by the exhaust gas flow, and the back surface side is also heated by the exhaust gas flow introduced into the exhaust gas flow introduction portion. A large heat receiving area can be obtained. Therefore, the temperature rise of the shroud portion is accelerated, and the thermal response of the shroud portion can be accelerated. Furthermore, it is possible to prevent the turbine wheel from approaching the turbine housing at the time of turbo startup and coming closer to the initial clearance or more.

In the present invention, preferably, the heat receiving body has a cylindrical shape, and a downstream end portion of the exhaust gas flow is fixed to an inner peripheral portion of the turbine housing, and the upstream end portion is deformable to be expandable and contractable.
According to this configuration, even if the turbine wheel is thermally deformed to the outside, the cylindrical heat receiving body is thermally deformed to the outside and escapes, so that the turbine wheel is difficult to approach the shroud portion, and a contact risk can be avoided.

In the present invention, it is preferable to have a reinforcing portion in the circumferential direction at the peripheral portion of the scroll portion.
According to this configuration, the rigidity of the scroll portion is enhanced by the reinforcing portion, and high shielding properties can be obtained even with a thin turbine housing.

In the present invention, it is preferable that the reinforcing portion is constituted by an uneven portion having a wavy cross section.
According to this configuration, the rigidity of the scroll portion can be increased by the wavy curved uneven portion, and even the wavy curved uneven portion can be easily formed by integrally molding it with the scroll portion when casting. it can.

In the present invention, preferably, the turbine housing is divided into the scroll portion and the shroud portion to be welded, and the heat receiving body is formed by exposing the end portion of the shroud portion to the inside of the scroll portion. The joining lower end portion may be joined to the outer peripheral portion of the shroud portion.
According to this configuration, the heat receiving body can be formed simultaneously with the joining of the scroll portion and the shroud portion, and the assemblability is improved.

  As described above, according to the present invention, even if the turbine housing is thinned, it is possible to simultaneously ensure the shielding property and thermal response of the turbine housing.

It is sectional drawing which showed the turbocharger of this invention. It is an enlarged view which shows the principal part of FIG. It is sectional drawing which shows the 2nd Embodiment of this invention. It is an enlarged view which shows the principal part of FIG. It is a figure which shows the temperature characteristic of a turbine housing. It is sectional drawing about the 3rd Embodiment of this invention. It is sectional drawing which shows the 4th Embodiment of this invention. It is sectional drawing which shows the 5th Embodiment of this invention.

Hereinafter, embodiments of a turbocharger according to the present invention will be described in detail.
However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to the description unless otherwise specified. Absent.

(First embodiment)
As shown in FIG. 1, a turbocharger 11 according to the present invention is provided with a compressor housing 12, and a compressor impeller 13 for supplying air is rotatably accommodated in the housing 12. A turbine housing 14 is provided on the air supply side of the turbocharger 11, and a turbine wheel 15 that is rotated by the exhaust gas flow G is supported in the turbine housing 14 so as to be rotatable about a rotation center line K. Contained.

  As shown in FIG. 2, the turbine housing 14 is formed with a scroll portion 16 for swirling the exhaust gas flow G to form a swirling flow, and the inner peripheral portion covers the outer peripheral edge portion 17 of the turbine wheel 15. In this way, the shroud portion 18 is formed. Accordingly, the exhaust gas flow G exhausted from the combustion chamber of the engine is swirled in the scroll portion 16 to rotate the turbine wheel 15, so that the turbine housing 14 and the turbine wheel 15 including the shroud portion 18 are heated to a high temperature. Will do.

  In particular, in the present invention, a thin-walled shroud portion 18 is formed, and the shroud portion 18 is provided with a plate-shaped heat receiving body 31 constituting the shroud 18. The heat receiving body 31 is provided on the outer peripheral edge portion of the rotor blade portion 17 of the turbine wheel 15 with a minute rear lance (chip clearance) C therebetween. Further, an exhaust gas flow introduction portion 32 that draws and introduces the exhaust gas flow G in the scroll portion 16 is formed on the back surface portion of the heat receiving body 31. Specifically, an exhaust gas flow introduction portion 32 that is largely opened in the scroll portion 16 is formed so that a sufficient exhaust gas flow G is drawn into and introduced into the back surface portion of the heat receiving body 31.

  Thus, by providing the plate-shaped heat receiving body 31 in the shroud portion 18, the heat receiving body 31 is heated and heated by the exhaust gas heat of the exhaust gas flow G, and the temperature rise of the shroud portion 18 is accelerated. Therefore, when the turbine wheel 15 is heated and thermally deformed by the exhaust gas flow G, the shroud portion 18 is thermally deformed so that the shroud portion 18 immediately spreads outward, and the outer peripheral edge of the rotor blade portion 17 of the turbine wheel 15. It is possible to avoid the clearance C from being narrowed due to abnormal approach.

  In particular, the side surface of the heat receiving body 31 on the turbine wheel 15 side is heated by the exhaust gas G, and the heat receiving body 31 is heated by the exhaust gas heat of the exhaust gas flow G introduced into the exhaust gas introducing portion 32 as indicated by arrows in the figure. The both sides of the heat receiving body 31 become heat receiving surfaces for thermally deforming the shroud portion 18 outward. Therefore, a large heat receiving area for quickly heating and raising the shroud portion 18 can be obtained by adding the heat receiving surface of the back portion to the heat receiving body 31, and the thermal responsiveness of the shroud portion 18 can be enhanced.

(Second Embodiment)
3 and 4 show a second embodiment. As shown in the figure, a guide portion 35 that forms an exhaust passage of the exhaust gas flow G is formed on the inner peripheral portion of the turbine housing 14 so as to cover the turbine wheel 15. The guide portion 35 has a moving blade portion of the turbine wheel 15. A plate-shaped heat receiving body 41 constituting a shroud portion is formed by approaching the outer peripheral edge portion 17 with a minute clearance C therebetween, and an exhaust flow for introducing an exhaust gas flow G to the back surface portion of the heat receiving body 41 A gas introduction part 42 is formed.

  As shown in FIG. 4, the heat receiving body 41 has a thin cylindrical shape such as stainless steel so as to allow deformation of the turbine wheel 15, and the downstream end portion of the exhaust gas flow G is fixed to the guide portion 35. The upstream end portion is configured to be deformable so as to freely expand and contract. Therefore, the side surface of the heat receiving body 41 on the turbine housing 14 side is heated by the exhaust gas flow G as shown by the arrows in the figure, and the exhaust gas flow G introduced from the exhaust gas flow introducing portion 42 causes the heat receiving body 41 to The back portion is also heated at the same time. By heating the both surface portions, the heat receiving body 41 immediately undergoes thermal deformation radially outward with the fixing portion 43 serving as a fulcrum, and heat that tends to escape to the thermal deformation of the turbine wheel 15 that tends to approach this. It becomes a deformation | transformation and a contact with the outer peripheral edge part of the moving blade part 17 of the turbine wheel 15 can be avoided effectively.

  Even if the turbine wheel 15 is slightly contacted with the heat receiving body 41 due to large thermal deformation or rapid thermal deformation, the heat receiving body 41 is formed of a thin plate material, and the heat receiving body 41 elastically deforming with the fixing portion 43 as a fulcrum is provided. The thermal deformation of the turbine wheel 15 can be absorbed. Accordingly, a minute clearance (chip clearance) C is formed in advance between the moving blade portion 17 of the turbine wheel 15 and the heat receiving body 41, and the outer peripheral edge portion of the moving blade portion 17 of the turbine wheel 15 and the guide portion of the turbine housing 14. A clearance H wider than the clearance C is formed between the clearance 35 and the heat receiving body 41 to allow thermal deformation.

  FIG. 5 shows a comparison between the thermal response characteristics of the conventional turbine housing and the present invention, with the vertical axis representing temperature and the horizontal axis representing time. As shown in the figure, the temperature rise (solid line) of the turbine housing 15 of the present invention is closer to the temperature rise of the turbine wheel than the temperature rise (thin wavy line) of the conventional turbine housing with respect to the temperature rise (thick wavy line) of the turbine wheel 15. It was obtained as an analysis result that it moved to. That is, it shows that high thermal responsiveness was obtained because the both surface portions of the heat receiving bodies 31 and 41 are simultaneously heated by the exhaust gas flow G.

(Third embodiment)
Further, as shown in FIG. 6, a reinforcing portion 52 is formed on the flat portion 51 formed on the peripheral portion of the scroll portion 16 in order to increase the rigidity. The reinforcing portion 52 is composed of two beads 53 attached in the circumferential direction along the outer peripheral portion of the flat portion 51 at a predetermined distance from each other. By forming the bead 53 in the flat part 51 in this manner, the rigidity of the scroll part 16 is increased, and high shielding performance can be obtained even if a thin-walled turbine housing 14 made of sheet metal is employed.

(Fourth embodiment)
FIG. 7 shows an uneven portion 54 formed in the circumferential direction as another embodiment of the reinforcing portion 52 in the flat portion 51 at the peripheral portion of the scroll portion 16. As shown in the drawing, the concavo-convex portion 54 having a waveform that is alternately curved in cross section is formed. The rigidity of the scroll part 16 can be increased by the uneven part 54 formed in a wave shape. Further, even a complicated shape such as an uneven portion 54 that is alternately curved can be easily formed by integrally forming it with the scroll portion 16 when the turbine housing 14 is cast.

(Fifth embodiment)
6 and 7 are formed by integrally molding the shroud portion 18 and the scroll portion 16 by casting, whereas FIG. 8 is formed by separating the shroud portion 18 and the scroll portion 16 and independently forming each other. These are butted together and welded together.
As shown in the figure, the turbine housing 14 is divided into a shroud portion 18 and a scroll portion 16, and the heat receiving body 31 and the exhaust gas introduction portion 32 are in a state where the edge of the shroud portion 18 is exposed in the scroll portion 16. The flange-shaped joint lower end 61 of the scroll portion 16 is welded to the outer peripheral portion of the shroud portion 18 so as to be formed. Therefore, the heat receiving body 31 can be formed simultaneously with the welding joint, and the assemblability can be improved.

  It is good to use for the turbocharger which can respond to the temperature rise and thermal deformation of the turbine housing due to the exhaust gas flow.

14 Turbine housing 15 Turbine wheel 16 Scroll part 17 Rotor blade outer edge part 18 Shroud part 31, 41 Heat receiving body 32, 42 Exhaust gas flow introduction part 53 Reinforcement part 54 Concavity and convexity C Minute clearance G Exhaust gas flow

Claims (5)

  A spiral scroll portion that forms a swirling flow of an exhaust gas flow in the turbine housing, a turbine wheel that is housed in the turbine housing and is rotated by the exhaust gas flow, and a shroud portion that forms an inner peripheral portion of the turbine housing; A plate-shaped heat receiving body that constitutes the shroud portion and is provided close to the outer peripheral edge of the moving blade of the turbine wheel with a small clearance, and the exhaust gas flow in the scroll portion on the back surface of the heat receiving body. A turbocharger comprising: an exhaust gas flow introduction portion that introduces and heats the heat receiving body from the back surface portion.   2. The heat receiving body according to claim 1, wherein the heat receiving body has a cylindrical shape, and a downstream end portion of the exhaust gas flow is fixed to an inner peripheral portion of the turbine housing, and the upstream end portion is deformable to be expandable and contractible. Turbocharger.   The turbocharger according to claim 1, further comprising a reinforcing portion in a circumferential direction at a peripheral portion of the scroll portion.   The turbocharger according to claim 3, wherein the reinforcing portion is constituted by an uneven portion whose section is curved in a wave shape.   The scroll lower portion and the shroud portion are divided so that the turbine housing is welded, and the lower end portion of the scroll portion is shroud so that the end of the shroud portion is exposed inside the scroll portion to form the heat receiving body. The turbocharger according to claim 1, wherein the turbocharger is joined to an outer peripheral portion of the portion.

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