JPH0343456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a housing structure of a turbocharger, and more specifically, a shroud surrounding a turbine wheel is provided at a distance from the turbine housing and positioned by a center housing, and the shroud is provided so as to reduce the heat generated by the turbine housing. The present invention relates to a housing structure that prevents the clearance between a shroud and a turbine wheel from changing due to strain.

(Prior Art) As described in Japanese Patent Publication No. 38-7653, a turbocharger connects a compressor housing and a turbine housing through a center housing, and connects a compressor impeller and a turbine housed in the compressor housing. A turbine wheel housed in the housing is connected to the turbine wheel by a shaft supported by the center housing. Since such turbochargers generally operate at high temperatures due to the influence of exhaust heat, each housing is made of heat-resistant steel such as stainless steel, and the center housing that supports the shaft is cooled to prevent the shaft from seizing. do. However, in such a turbocharger, since the turbine housing and the center housing are in direct contact over a large area, the amount of heat transferred to the center housing is large.
Furthermore, since a relatively large tolerance is allowed in the assembly of the center housing and the turbine housing, it is difficult to accurately control the clearance between the turbine housing and the turbine wheel.

Therefore, for the present applicant, the patent application filed in 1983-
In Specification No. 124996 (submitted May 30, 1985), etc., a base plate is fitted into the turbine housing between the turbine housing and the center housing, and a top plate within the turbine housing is fixed to this base plate. The proposed turbocharger surrounds a turbine wheel and directs exhaust gas to the turbine wheel to drive the turbine wheel. In the turbocharger according to this earlier application, the base plate prevents heat transfer to the center housing, and the top plate is arranged concentrically around the outer periphery of the turbine wheel, so that the clearance (nozzle part) on the outer periphery of the top plate is formed between
To accurately manage the clearance around the outer circumference of a turbine wheel.

(Problems to be Solved by the Invention) However, in the turbocharger according to this prior application, since the base plate fits into the turbine housing and the outer circumferential surface of the base plate is in close contact with the inner circumferential surface of the turbine housing, When the turbine housing experiences thermal distortion due to exhaust heat, the base plate also becomes distorted due to this thermal distortion.
A disadvantage was that the concentricity between the turbine wheel and the top plate was distorted due to the distortion of the base plate. In other words, a turbine housing generally has an asymmetrical shape in which a spiral scroll passage that generates a swirling flow in the exhaust gas and an exhaust inlet opening tangentially to the scroll passage are formed, so that the thermal strain is reduced. The concentricity was also large locally, and the concentricity was also greatly distorted due to the distortion of the base plate. As a result, interference occurs between the turbine wheel and the top plate forming the nozzle portion, and the amount of exhaust gas leaking from around the turbine wheel also increases, causing a reduction in turbine efficiency.

The present invention has been made in view of the above-mentioned drawbacks, and provides a housing structure for a turbocharger that prevents concentricity between the top plate and the turbine wheel from being lost due to thermal distortion of the turbine housing, and prevents interference between the turbine wheel and the turbine wheel. The purpose is to prevent a decline in turbine efficiency.

(Means for Solving the Problems) A housing structure of a turbocharger according to the present invention connects a compressor housing in which a compressor impeller is housed and a turbine housing in which a turbine wheel is housed through a center housing, and A shroud, which is a member separate from the turbine housing and in which a variable nozzle consisting of a fixed vane and a movable vane is arranged in an annular manner, is disposed within the turbine housing, and the shroud surrounds the turbine wheel, and the turbine wheel and the compressor are surrounded by the shroud. In a turbocharger that connects an impeller by a shaft supported by the center housing, the shroud is fitted into the center housing and protrudes radially into a fitting portion of at least one of the shroud or the center housing. A plurality of alignment parts are formed in the circumferential direction, and the protruding ends of the alignment parts are brought into contact with the other fitting part of the center housing or the shroud to align the shroud and the center housing. The gist is that a space is formed between the alignment portions between the center housing and the shroud.

(Function) According to the housing structure of the turbocharger according to the present invention, the shroud is fitted into and supported by the center housing that maintains a relatively constant temperature, and the shroud is provided with a projecting portion on the fitting portion of either the shroud or the center housing. Since the aligned part contacts the other fitting part and is aligned with the center housing as a reference, the relative position between the shroud and the turbine housing is not affected by the temperature of the turbine housing, etc. . Therefore, the clearance between the outer periphery of the turbine wheel and the shroud can be maintained substantially constant regardless of the presence or absence of thermal distortion of the turbine housing, and the amount of exhaust gas leaking through the interference of the turbine wheel or the clearance on the outer periphery is increased. This prevents a decrease in turbine efficiency.

Further, a gap is formed between the alignment portions between the shroud and the center housing, and this gap functions as a heat insulating layer. Therefore, the amount of heat transferred to the center housing can be reduced, and smooth rotation of the shaft is ensured.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

1 to 3 show a turbocharger according to an embodiment of the present invention, in which FIG. 1 is a longitudinal cross-sectional view of the whole, FIG. 2 is a cross-sectional view taken along the - arrow in FIG.
4 is a front view of the center housing, and FIG. 5 is a front view of the base holding member.

In the figure, reference numeral 11 denotes a compressor housing that rotatably accommodates a compressor impeller, which will be described later.
Reference numeral 2 indicates a turbine housing that rotatably houses a turbine wheel, which will be described later. Reference numeral 13 indicates a center housing that supports a shaft that connects the compressor impeller and the turbine wheel. are integrally joined in between. The compressor housing 11 has a back plate 14 with bolts 15 and a mounting plate 16 at the left open end in the figure.
An axial passage 17 and a scroll passage 18 are defined therein. Back plate 1
4 is connected to the center housing 13 by bolts 19. The left end of the axial passage 17 in the figure communicates with the center of the scroll passage 18, and a compressor impeller 2 attached to the right end of the shaft 20 is connected to the part where these passages 17 and 18 communicate.
1 is rotatably housed. Axial passage 17
Haha Intake intake port 17a that introduces intake air to the right end in the figure
is open, and the scroll passage 18 has an intake outlet (not shown) opened upwardly that communicates with a combustion chamber of an engine (not shown).

Two bearing parts 22 and 23 are formed inside the center housing 13, and these bearing parts 22 and 23
The shaft 2 is connected to the bearing holes 22a and 23a formed in the shaft 2 through float bearings 24 and 25, respectively.
0 is rotatably supported. Shaft 20
The right end in the figure rotatably penetrates the back plate 14 via the bush 26 and is connected to the compressor impeller 21, and the left end in the figure is connected to the turbine wheel. Note that 27 is a washer, 28 is a collar, and 29 is a thrust bearing, which are interposed between the stepped portion of the shaft 20 and the bush 26.

The center housing 13 also includes float bearings 24 and 2 above the bearings 22 and 23.
The oil supply passage 30 that supplies lubricating oil to the bearing portion 2
Oil drain passage 31 that discharges lubricating oil below 2, 23
A hole 31 (designated with the same reference numeral as the oil drain passage 31) is formed. The refueling passage 30 is
An introduction hole 30a whose upper end is open, and the introduction hole 30a
The right end in the figure is the thrust bearing 2.
A horizontal hole 30b opened on the sliding surface with the horizontal hole 3
0b and are connected to the bearing holes 22a, 2, respectively.
Two distribution holes 30c, 30 opened on the circumferential surface of 3a
It is composed of d and. The upper end of the introduction hole 30a is connected to a lubricating oil supply source such as an oil pump (not shown), and the lower end of the hole 31 is connected to an oil pan or the like. These oil supply passage 30 and oil drain passage 31 guide lubricating oil supplied from a lubricating oil supply source to the bearings 24, 25, 29 to provide lubrication and cooling, and then return this lubricating oil to the oil pan. to recover. Note that 32 is a water jacket for cooling water formed on the turbine housing 12 side of the oil supply passage 30 and the oil drainage passage 31, and this water jacket 32 has a water inlet at the bottom and a drain opening at the top. . This water jacket 32 is attached to the turbine housing 1.
It also prevents heat transfer from the bearing part 2, and also evaporates the cooling water during heat soak back and uses the heat of vaporization to cool the bearing part 2.
Cool down 2 and 23.

The turbine housing 12 has stud bolts 3
3 is screwed and fixed to the center housing 13 by a mounting plate 35 fastened to the stud bolt 33 with a nut 34. The opening end of the turbine housing 12 on the right side in the figure is closed by a vane holding member (shroud) 36 whose outer periphery is sandwiched between the turbine housing 12 and the center housing 13. A top plate (shroud) 38 fixed by bolts 37 fits into the inner circumference. The turbine housing 12 has a scroll passage 39 and an outlet passage 40 defined therein, and an exhaust inlet 39a opening tangentially to the scroll passage 39 and an exhaust exhaust opening opening at the left end of the exit passage 40. An outlet 40a is formed. The center of the scroll passage 39 and the exit passage 40
A turbine wheel 41 fixed to the left end of the shaft 20 is rotatably disposed in a portion where these passages 39 and 40 communicate with each other.

The top plate 38 is connected to the turbine housing 1
A cylindrical portion 38a fitted into the inner end of the outlet passage 40 of No. 2 through a seal ring 42;
and a disk portion 38b integrally extending in the radial direction from the axial center portion of the outer periphery. Cylindrical part 3
The aforementioned turbine wheel 41 is rotatably disposed around the outer periphery of the turbine wheel 8a with a predetermined clearance, and the disk portion 38b divides the scroll passage 39 into an outer circumferential path 39b and an inner circumferential path 39c.
This top plate 38 is located between the disk portion 38b and the inner wall of the turbine housing 12 and between the cylindrical portion 3
8a and the inner circumferential wall of the turbine housing 12, each having a slight clearance,
The aforementioned bolt 3 passes through the disk portion 38b, the vane holding member 36, and a heat shield plate (described later) from the turbine housing 12 side and is screwed into the vane holding member 36.
7 to the vane holding member 36. Note that the bolt 37 is attached to the center housing 13.
The side end portion is welded to the center housing 13 side end portion of the heat shield plate to prevent loosening.

The vane holding member 36 includes a disk portion 36a through which the shaft 20 rotatably passes, and four wing-shaped fixed vanes that integrally extend from the outer circumferential portion of the disk portion 36a toward the top plate 38 side in the axial direction. 4
It is composed of 3. A flange 36b is integrally formed on the outer periphery of the disk portion 36a, and an annular boss 36c is integrally formed on the end surface on the side of the center housing 13. As shown in detail in FIG. 5, the flange 36 has eight alignment parts 50 formed on the side surface on the center housing 13 side that protrude toward the center housing 13, and as described above, the turbine housing 12 and the center housing 13. As shown in FIG.
The tip contacts the center housing 13, determines the axial position of the vane holding member 36 with respect to the center housing 13, and has an alignment portion 5 between the center housing 13 and the vane holding member 36.
Adiabatic gaps 50a are formed between 0 and 50a scattered in the circumferential direction.

The boss 36c is fitted into an alignment hole 13a formed in the end surface of the center housing 13 on the turbine housing 13 side. This center housing 1
As shown in FIG. 4, the alignment hole 13a of No. 3 is
Four alignment parts 51 protruding radially inward on the inner peripheral surface are integrally formed at equal intervals in the circumferential direction,
The outer circumferential surface of the boss 36c abuts the tip of each alignment portion 51 and fits into the alignment hole 13a, and a gap between the alignment portions 51 is formed between the inner circumferential surface of the alignment hole 13a and the outer circumferential surface of the boss 36c. Four heat insulating gaps 51a are formed which are scattered in the circumferential direction. Further, a heat shield plate 44 is fitted to the inner circumference of the boss 36c, and a heat insulating layer 44 is formed between the heat shield plate 44 and the disk portion 36a.
It forms a. The outer peripheral end of the heat shield plate 44 is fixed to the vane holding member 36 by welding. This vane holding member 36 has clearances 59a and 59b between the outer circumferential wall of the disk portion 36a and the outer circumferential wall of the flange 36b, and the inner circumferential wall of the turbine housing 12, respectively, and the alignment portion 50a of the flange 36b is located between the center housing 13 to determine the axial position, and the boss 36c comes into contact with the alignment portion 51 of the alignment hole 13a of the center housing 13 to determine the concentricity.

In addition, in FIG. 1, 60a is the center housing 1.
Similarly, 60b is a knock pin for aligning the vane holding member 36 and the top plate 38 in the rotational direction.

As shown in FIG. 2, the fixed vanes 43 have a partially arcuate shape and are arranged concentrically with the turbine wheel 41 at equal intervals in the rotational direction. Four partially arcuate movable vanes 45 are arranged between these fixed vanes 43, and these fixed vanes 43 and movable vanes 45 form outer circumferential paths 39b and inner circumferential paths 39c of the scroll passage 39, respectively. Four variable apertures 46 are configured between them. Each of the movable vanes 45 has one end fixed to a pin 47 that rotatably passes through a hole 36b formed in the disk portion 36a of the vane holding member 36, and tilts as the pin 47 rotates to adjust the position of the variable diaphragm 46. Change the flow path area (opening degree).

The end of the pin 47 protruding toward the center housing 13 is connected to an actuator via a link mechanism (not shown), and is driven by the actuator. This link mechanism and the like are described in detail in the specification of Japanese Patent Application No. 125000/1988 previously filed by the present applicant, so the following explanation will be omitted.

In addition, 48 is a disk-shaped shield plate whose outer peripheral edge is sandwiched between the inner peripheral end of the heat shield plate 44 and the outer peripheral wall of the center housing 13, and 49 is a mounting stud screwed onto the turbine housing 12. is a bolt,
The shield plate 48 prevents exhaust heat from being transferred to the center housing 13 together with the heat shield plate 44 described above.

Next, the operation of this embodiment will be explained.

In this turbocharger, when the rotational speed of the engine is relatively low and the flow rate of exhaust gas is low, the movable vane 45 is positioned as shown in FIG. 2, and the variable throttle 46 is set to the minimum opening degree. For this reason, the exhaust inlet 3
The exhaust gas introduced from 9a flows through the scroll passage 39.
It is accelerated from the outer circumferential passage 39b through the variable throttle 46 and flows into the inner circumferential passage 39c, and a swirling flow is generated within the inner circumferential passage 39c to drive the turbine wheel 41. Therefore, the compressor impeller 21 is rotated at high speed to pressurize the suction, thereby ensuring a supercharging effect when the engine is operated at low speed.

Further, when the rotational speed of the engine increases and the flow rate of exhaust gas also increases, the movable vane 45 is driven toward the center in accordance with the rotational speed of the engine, and the opening degree of the variable throttle 46 increases. Therefore, the flow resistance of the exhaust gas is also reduced, and the exhaust back pressure of the engine can be reduced. Then, as described above, the turbine wheel 41 is driven by the exhaust gas, and the compressor impeller 21 pressurizes the intake air to perform supercharging.

On the other hand, in this turbocharger, the turbine housing 12 is heated by the heat of the exhaust gas flowing through the scroll passage 39 etc., and the turbine housing 12 etc. cause thermal expansion. The alignment portion 51 of the alignment hole 13a and the alignment portion 50 of the flange 36b are connected to the center housing 13.
Since the concentricity and axial position of the vane holding member 36 and the top plate 38 fixed to the vane holding member 36 are determined based on the center housing 13 by contacting with The clearance between the top plate 38 and the turbine wheel 41 can be kept constant during operation when the turbine housing 12 and the like are heated. That is, the center housing 13 is cooled by lubricating oil and cooling water and remains at a low temperature (approximately 300 ℃) even during operation.
[°C] or less), the thermal expansion (thermal strain) of the center housing 13 is minimal, and the turbine wheel 41 and the center housing 13 supported by the shaft 20 are
The clearance between the top plate 38 and the top plate 38 aligned by the vane holding member 36 hardly changes. Therefore, there is no increase in the amount of leaked exhaust gas due to an increase in the clearance between the top plate 38 and the turbine wheel 41, and there is no interference between the turbine wheel 41 and the top plate 38 due to a decrease in the clearance, thereby improving the turbine efficiency. High reliability can be obtained without reducing the speed and without causing interference with the turbine wheel due to misalignment.

In addition, in this turbocharger, since the center housing 13 has an asymmetrical shape, thermal distortion becomes locally large during heating, but there is a clearance 59a, 59b between the outer peripheral surface of the vane storage member 36 and the turbine housing 12. However, since there is also a clearance between the top plate 38 and the turbine housing 12, the thermal strain of the turbine housing 12 is absorbed by these clearances 59a and 59b, and the top plate is affected by the thermal strain of the turbine housing 12. 38 and the vane holding member 36 are not distorted. Therefore, the clearance between the top plate 38 and the turbine wheel 41 is not affected by local thermal distortion of the turbine housing 12, and as described above, the clearance between the top plate 38 and the turbine wheel 41 is Interference with 38 can be prevented.

Furthermore, in this turbocharger, the vane holding member 36 and the center housing 13 are in contact with each other through the alignment portions 50 and 51, resulting in a small contact area (heat transfer area). Insulation between 50a,
51a, the amount of heat transferred from the vane holding member 36 to the center housing 13 can be reduced. Therefore, it is possible to prevent the bearing parts 22, 23, etc. of the shaft 20 from becoming high temperature,
Reliability can be improved. Also, when assembling the vane retaining member 36 and the center housing 13, it is possible to reduce the influence of foreign matter such as dust on the assembly accuracy, and the clearance between the vane retaining member 36 and the turbine wheel 41 is maintained at the time of assembly. This can prevent the product from being affected by garbage, etc.

(Effects of the Invention) As explained above, according to the housing structure of the turbocharger according to the present invention, a plurality of positioning portions are provided protruding from one of the shroud or the center housing, and the positioning portions are connected to each other through the positioning portions. The shroud and center housing are fitted with the center housing as a reference, reducing the contact area between the shroud and the center housing, and forming a heat insulating gap between the alignment parts between the shroud and the center housing. It is possible to maintain a constant clearance between the turbine wheel and shroud regardless of the temperature of the center housing, preventing a decrease in turbine efficiency and interference between the turbine wheel and shroud, and also reducing the amount of heat transferred to the center housing. can get.

[Brief explanation of drawings]

FIGS. 1 to 3 show the housing structure of a turbocharger according to an embodiment of the present invention.
Figure 2 is a longitudinal sectional view, Figure 2 is a sectional view taken along the - arrow in Figure 1, Figure 3 is an enlarged sectional view of main parts, Figure 4 is a front view of the center housing, and Figure 5 is a front view of the vane holding member. It is. 11... Compressor housing, 12... Turbine housing, 13... Center housing, 13a
... alignment hole, 20 ... shaft, 21 ... compressor impeller, 36 ... vane holding member (shroud), 36c ... boss, 38 ... scroll passage, 4
0... Outlet passage, 41... Turbine wheel, 43...
Fixed vane, 44... Heat shield plate, 50, 51... Positioning part, 50a, 51a... Insulation gap, 55a, 55
b...Clearance, 60a, 60b...Knock pin.

Claims (1)

[Scope of Claims] 1. A compressor housing in which a compressor impeller is housed and a turbine housing in which a turbine wheel is housed are joined via a center housing, and a member separate from the turbine housing is provided in the turbine housing, and A shroud in which a variable nozzle consisting of a fixed vane and a movable vane is arranged in an annular manner is arranged, and the shroud surrounds a turbine wheel, and the turbine wheel and the compressor impeller are connected by a shaft supported by the center housing. In the turbocharger which is connected by a thread, the shroud is fitted into the center housing, and a plurality of positioning portions protruding in the radial direction are formed in the fitting portion of at least one of the shroud or the center housing in the circumferential direction. The protruding end of the alignment part is brought into contact with the other fitting part of the center housing or the shroud to align the shroud and the center housing, and the position between the center housing and the shroud is adjusted. A housing structure for a turbocharger characterized by forming a space between mating parts. 2 A plurality of positioning portions protruding from at least one surface of the surface of the center housing facing the shroud or the surface of the shroud facing the center housing in the axial direction are formed in a spaced manner, and the positioning portions are Claims characterized in that the center housing and the shroud are brought into contact with the other surface to align the center housing and the shroud, and a space is formed between the alignment portions between the shroud and the center housing. A housing structure of the turbocharger according to item 1.