JP4153722B2 - Axial-flow turbine for exhaust-driven turbocharger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a turbine casing composed of a turbine inlet chamber with a gas outlet side wall and a turbine exhaust chamber with a gas inlet side wall, and a turbine disk with moving blades supported by a shaft is disposed in the casing. The present invention relates to an axial-flow turbine in an exhaust-driven supercharger in which a flow path is formed by an exhaust diffuser and bounded in a state where a flow path is formed by an exhaust diffuser and a rupture protector is provided in an axial range of a turbine disk in a turbine casing.
[0002]
[Prior art]
Today, exhaust-driven superchargers are operated at very high peripheral speeds in order to obtain a high supercharging pressure. Therefore, especially in a large exhaust-drive supercharger, a damaged turbine disk or blade fragment can be captured only after an expensive structural treatment is applied to the turbine casing.
[0003]
Conventionally, a protection ring and a burst protection ring extending in the axial direction have been provided in the range of the turbine disk in the turbine casing.
[0004]
The basic structure and operation of such an axial turbine in an exhaust-driven supercharger is well known and will therefore not be described in detail here. That is, for example, European Patent Application No. 0806547 describes an axial flow turbine in which the gas inlet side wall of the turbine exhaust chamber performs a burst protection function against the turbine disk. To that end, there is a burst guard formed as a ring in the form of a monolithic part extending in the radial direction of the gas inlet side wall of the turbine exhaust chamber, and an axially extending member arranged directly or upstream in the turbine inlet chamber. Are connected through.
[0005]
However, with the development of axial flow turbines for exhaust-driven turbochargers, there is a tendency to change from long and thin blades to short and wide blades, so-called “wide code” blades with a small number of blades. Accompanying this, the individual blades become heavier, and the turbine discs that must reliably hold these blades even at high peripheral speeds become wider. Of course, this measure increases the rotational mass. For this reason, today there is a considerable centrifugal force associated with a normal high peripheral speed, and this centrifugal force must be made without problems with good protective measures.
[0006]
Conventionally, a cover ring for a turbine disk screwed to the above-described burst protection body or diffuser in the form of a burst protection ring, which is an integral part of the turbine exhaust chamber, for example, with a tightening ring, It was enough to prevent it from jumping out of the room.
[0007]
However, the above-mentioned measures are no longer necessary to ensure safe burst protection as conditions become more severe, preventing breakage of the turbine casing outer wall and preventing personal injury or damage to adjacent machine parts. not enough.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide an axial turbine of the type described at the beginning to assist the outside of the turbine casing so that damaged turbine discs and blade fragments jump out of the turbine casing even at extremely high peripheral speeds. In order to prevent this without the need to provide an appropriate rupture protection body, the object is to form it simply and inexpensively.
[0009]
[Means for Solving the Problems]
This problem is solved by the means described in claim 1.
[0010]
According to the present invention, the outer wall of the exhaust diffuser is formed with an outer contour portion and an inner contour portion in the radial direction in the axial range of the turbine disk, and an annular support wall portion is provided between both contour portions. The outer contour of the outer wall is formed in the form of an annular extension that extends beyond the axial extent of the turbine disk, and the cover ring for the turbine disk and blades is connected to the support wall of the exhaust diffuser and the inner contour of the outer wall. The turbine inlet chamber and the turbine exhaust chamber are connected to each other so that the gas inlet side wall of the exhaust chamber is located on the center plane of the turbine disk in the radial direction. A three-stage burst protection action that satisfies three requirements can be achieved.
[0011]
When the turbine disk or the turbine blade is damaged, first (as a first stage), the debris collides with a cover ring supported by the support wall portion of the exhaust diffuser. If the debris is so large that the covering ring and the support wall cannot withstand the impact, the breakage of the covering ring and the supporting wall will dissipate some of the kinetic energy of the debris.
[0012]
At least the cover ring may be made of a non-brittle material such as steel or alloy steel, and the other parts of the axial turbine may be formed from a cast as is well known. This provides the best energy dissipation. For the same purpose, the cover ring may be supported in contact with the support wall and fixed to the exhaust diffuser by means of a flexible joint element.
[0013]
In the second stage, the debris impinges radially outward on the annular extension of the outer wall outer contour of the exhaust diffuser. The annular or cylindrical extension member is formed such that it extends beyond the axial extent of the turbine disk, thereby absorbing most of the kinetic energy of the debris. Therefore, the annular extending member of the outer wall outer contour portion of the exhaust diffuser may be reinforced by ribs arranged in the radial direction.
[0014]
In the third stage, the residual energy of the debris is absorbed by the gas inlet side walls of the turbine exhaust chamber located in the radial direction and directly over the central plane of the turbine disk. The solid flange joint between the turbine inlet chamber, the diffuser outer wall, and the turbine exhaust chamber may be formed firmly.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0016]
FIG. 1 is a sectional view of a part of an axial turbine of an exhaust-driven supercharger according to the present invention. The figure shows only those components that are important to an understanding of the present invention. For example, the compressor side of the exhaust drive supercharger is not shown. The direction of exhaust flow is indicated by arrows.
[0017]
The exhaust-driven supercharger of the type on which FIG. 1 is based comprises an axial turbine 1. This turbine 1 has a turbine casing composed of a turbine inlet chamber 2 having a gas outlet side wall 3 and a turbine exhaust chamber 4 having a gas inlet side wall 5. A turbine disk 7 with a moving blade 8 supported by a shaft 6 is disposed in the turbine casing.
[0018]
The moving blade 8 of the turbine disk 7 is bounded on the outside by an exhaust diffuser 9 and is accommodated in the flow path 14 by the exhaust diffuser 9. The outer wall 10 of the exhaust diffuser 9 is formed with an outer contour portion 11 and an inner contour portion 12 in the radial direction in the axial range of the turbine disk 7. A cylindrical or annular support wall 13 is integrally formed between the outer contour portion 11 and the inner contour portion 12. The outer contour 11 is formed in the form of an annular or cylindrical extension member, which extends beyond the axial extent of the turbine disc 7.
[0019]
A flow path 14 exists between the turbine disk 7 and the turbine casing. This flow path 14 receives exhaust gas from an engine (not shown) and guides it to the rotor blades 8 of the turbine disk 7 as is well known. A nozzle ring including an outer ring 15 and an inner ring 16 is fitted upstream of the flow path 14. This nozzle ring is connected to the turbine inlet chamber 2 by a joint element 17 with flanges 18 on the outer ring 15 and the inner ring 16.
[0020]
Between the nozzle rings 15 and 16 and the exhaust diffuser 9 in the axial direction, a cover ring 19 for the rotor blade 8 of the turbine disk 7 forms a gap 28 between the outer ring 15 and the cover ring 19 of the nozzle ring, and the inner ring 16 A gap 20 is formed between the turbine disk 7 and the outer wall inner contour 12 of the exhaust diffuser 9 in airtight contact with the flow path 14. As is well known, a gap 21 is also formed between the turbine disk 7 and the inner wall 22 of the exhaust diffuser 9.
[0021]
The cover ring 19 is supported in contact with the support wall 13 of the exhaust diffuser 9 and is fixed to the exhaust diffuser 9 by a flexible joint element, that is, an extension bolt 27.
[0022]
The turbine inlet chamber 2 and the turbine exhaust chamber 4 are coupled to each other so that the gas inlet side wall 5 of the turbine exhaust chamber 4 is positioned directly over the central plane 23 of the turbine disk 7 in the radial direction.
[0023]
The annular extension member of the outer contour portion 11 of the exhaust diffuser 9 has an annular mounting flange 24 or a plurality of individual mounting flange portions on the end face side, and the flange 24 is a joint of the turbine inlet chamber 2 and the turbine exhaust chamber 4. The rigid joint element 25 is screwed to the turbine inlet 2 and the turbine exhaust chamber 4.
[0024]
Furthermore, the annular extension member of the outer contour 11 is reinforced by ribs 26 arranged in the radial direction.
[Brief description of the drawings]
FIG. 1 is a partial sectional view of an axial turbine of an exhaust drive supercharger according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Axial flow turbine 2 Turbine inlet chamber 3 Gas outlet side wall 4 Turbine exhaust chamber 5 Gas inlet side wall 6 Shaft 7 Turbine disk 8 Rotor blade 9 Exhaust diffuser 10 Outer side wall 11 Outer side wall outer contour 12 Outer side wall inner contour 13 Support wall Part 14 Flow path 15 Nozzle ring outer ring 16 Nozzle ring inner ring 17 Joint elements 18, 24 Flange 19 Cover rings 20, 21, 28 Gap 22 Exhaust diffuser inner wall 23 Turbine disk central plane 25 Rigid joint element 26 Rib 27 Flexible joint element

Claims (6)

A turbine casing having a turbine inlet chamber with a gas outlet side wall and a turbine exhaust chamber with a gas inlet side wall is provided, and a turbine disk with moving blades supported by a shaft is disposed in the casing, and the outside of the disk is exhausted In the axial flow turbine of an exhaust drive supercharger that is bounded in a state where a flow path is formed by a diffuser and a bursting protection body is provided in the axial range of the turbine disk in the turbine casing,
An outer wall (10) of the exhaust diffuser (9) is formed in the axial range of the turbine disc (7) with an outer contour (11) and an inner contour (12) in the radial direction. An annular support wall portion (13) is provided between the portion (11) and the inner contour portion (12), and the outer contour portion (11) of the exhaust diffuser outer wall (10) is in the axial direction of the turbine disk (7). Formed in the form of an annular extension member extending beyond range, the cover ring (19) for the turbine disk (7) and the rotor blade (8) is connected to the support wall (13) of the exhaust diffuser (9) and the inner side of the outer wall Between the turbine inlet chamber (2) and the turbine exhaust chamber (4), the gas inlet side wall (5) of the turbine exhaust chamber (4) in the radial direction of the turbine disc (7). Connected to each other so that they lie on the midplane (23) Axial flow turbine, characterized in that the. The axial turbine according to claim 1, characterized in that the covering ring (19) is supported in contact with the support wall (13) and is fixed to the exhaust diffuser (19) by means of a flexible coupling element (27). 2. An axial turbine according to claim 1, characterized in that the annular extension of the outer wall outer contour (11) of the exhaust diffuser (9) is reinforced by ribs (26) arranged in the radial direction. The shaft according to claim 1 or 3, further comprising a mounting flange (24) sandwiched in a joint between the turbine inlet chamber (2) and the exhaust chamber (4) on the terminal end side of the annular extending member (11). Flow turbine. The axial turbine according to claim 1 or 4, characterized in that the joint between the turbine inlet chamber (2) and the exhaust chamber (4) is a rigid joint element (25). 2. The axial flow turbine according to claim 1, wherein at least the covering ring (19) of the exhaust diffuser (9) is made of a non-brittle material such as steel or alloy steel.

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