JP3801367B2 - Exhaust gas turbocharger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas turbine apparatus that performs supercharging using an axial turbine.
[0002]
[Prior art]
High output is desired for large diesel engines used for power generation.
[0003]
Therefore, an exhaust gas turbocharger has been provided particularly for large diesel engines.
[0004]
In such an exhaust gas turbine supercharger, an axial flow turbine is disposed as a moving blade in a cylindrical casing so as to face an exhaust gas inlet formed at one end of the casing, and further an exhaust gas is introduced. A structure having a turbine side in which a nozzle portion is connected to a mouth and a compressor side in which a compressor wheel is assembled coaxially with an axial turbine is used.
[0005]
In this exhaust gas turbine supercharger, when the exhaust gas of a diesel engine is ejected from the nozzle part to the blades of the axial turbine, the axial turbine rotates and this rotation is transmitted to the compressor wheel through the shaft, compressing the air. This is pumped to the diesel engine as combustion air.
[0006]
By the way, in order to obtain a low running cost in a large diesel engine, a low quality fuel oil, for example, heavy oil, is used as a fuel in particular. Many are included.
[0007]
For this reason, in an exhaust gas turbine supercharger combined with a large diesel engine, carbon in the exhaust gas easily accumulates on the inner surface of the casing close to the blade tip (outer peripheral end) of the axial turbine during operation.
[0008]
[Problems to be solved by the invention]
By the way, the casing of the exhaust gas turbocharger cools and contracts when the engine stops. This contraction acts in the direction of narrowing the gap between the blade tip and the casing inner surface.
[0009]
For this reason, when a large amount of carbon accumulates on the inner surface of the casing, the blade tip is buried in the accumulated deposit due to thermal contraction of the casing while the engine is stopped when the engine is stopped. The blade tip may stick when it cools and clumps, but once the blade tip sticks, the axial turbine will not rotate, and the next time the diesel engine starts, the axial turbine will rotate. That is, the turbocharger may not operate.
[0010]
Conventionally, due to such problems, the blades and the inner surface of the casing are regularly cleaned. However, when the engine is started, the axial turbine may not operate due to the accumulated carbon particles. there were.
[0011]
The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide an exhaust gas turbine supercharger capable of preventing the axial flow turbine from becoming unrotatable by deposits accumulated on the inner surface of the casing. There is.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the exhaust gas turbocharger according to claim 1 is configured such that the outer peripheral portion of the casing is supported by a bracket at a point downstream of the position of the axial turbine to form an exhaust gas introduction port. The radial displacement of the casing end is affected to the wall portion facing the tip of the blade, and the end of the nozzle portion is formed by an annular step between the casing end forming the exhaust gas introduction portion and the male and female from the inside. is fitted to suit fits the fitting portion which is formed, in the radial direction of the thermal expansion displacement of the nozzle portion transmitted to the casing end, it adopts a structure that is widened blade tip and the opposite wall part of the casing Then, using the behavior of the nozzle part thermally expanding before the casing when the engine is started, the casing end is pushed from the inside by the thermal expansion displacement of the nozzle part at the initial stage of engine startup. And blade tip away from the casing inner surface.
[0013]
As a result, even if the blade tip adheres to the deposit accumulated on the inner surface of the casing, the blade tip separates from the deposit.
[0014]
In other words, the axial turbine can escape from the non-rotatable state, and the original supercharger can be operated.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the first embodiment shown in FIG. 1 and FIG.
[0020]
FIG. 1 shows the main part of an exhaust gas turbocharger for a large diesel engine to which the invention of claim 1 is applied, in which 1 is the turbine side and 10 is the compressor side.
[0021]
The turbine side 1 has a gas outlet guide cylinder 3 (corresponding to a cylindrical casing) having an exhaust gas inlet 2 formed at the right end. An axial turbine 4 is rotatably disposed in the gas outlet guide tube 3 near the exhaust gas inlet 2. The axial turbine 4 is configured to have a large number of blades 4 a on the outer peripheral side, and these blades 4 a face the exhaust gas inlet 2. The exhaust gas introduction port 2 includes a nozzle outer ring 5 (corresponding to a nozzle part) in which a stationary blade 5a is incorporated, and an exhaust gas introduction member 6 connected in series to form an inlet part through which exhaust gas flows. is doing. As a result, the exhaust gas exhausted from the large diesel engine is jetted to the blade 4 a after being jetted by the nozzle outer ring 5.
[0022]
Of each part of the inlet part, the nozzle outer ring 5 and each end part of the exhaust gas introducing member 6 are connected. Further, the end face of the cylinder forming the exhaust gas inlet 2 and the end face of the nozzle outer ring 5 are formed by a fitting portion 7 formed by male and female annular steps 7a and 7b formed on each end face. It is fitted so that it may fit from the inner side of a cylinder end surface. With this fitting structure, the thermal expansion displacement in the radial direction of the nozzle outer ring 5 is made by utilizing the fact that the nozzle outer ring 5 is thermally expanded by the heat of the exhaust gas prior to the gas outlet guide tube 3 at the initial start of the engine. Thus, the entire circumference of the cylinder end of the gas outlet guide cylinder 3 is pushed and expanded.
[0023]
The gas outlet guide tube 3 is supported by a bracket 8 formed at a point on the outer peripheral portion downstream from the position of the axial turbine 4. By this support, the radial displacement at the tube end of the gas outlet guide tube 3 is propagated (transmitted) to the tube wall portion of the gas outlet guide tube 3 facing the blade tip. That is, the structure is such that the tubular wall portion facing the tip of the blade is expanded by the thermal expansion displacement of the nozzle outer ring 5 transmitted to the gas outlet guide tube 3.
[0024]
On the other hand, the compressor side 10 has a compressor housing 12 in which a compressor wheel 11 is rotatably housed. The compressor wheel 11 is coaxially connected to the turbine-side axial turbine 4 via the shaft 13 and compresses the air by the rotational force obtained by the axial turbine 4, so that the diesel engine The combustion air can be pumped to the intake side.
[0025]
The axial flow turbine 4 is prevented from becoming unrotatable by carbon deposited on the inner surface of the gas outlet guide tube 3 by the structure in which the gas outlet guide tube 3 is expanded.
[0026]
That is, assume that the large diesel engine is started. Then, exhaust gas exhausted from the engine is guided to the nozzle outer ring 5 through the exhaust gas introduction member 6. This exhaust gas is jetted from the nozzle outer ring 5 to the blades 4 a of the axial turbine 4 to drive the axial turbine 4. The exhaust gas that has passed through the axial turbine 4 is exhausted from an exhaust gas outlet passage 9 formed on the downstream side of the axial turbine 4.
[0027]
The rotational force of the axial turbine 4 obtained by the exhaust energy is transmitted to the compressor side 10 via the coaxial shaft 13 to rotate the compressor wheel 11.
[0028]
As a result, a large amount of combustion air is sent to the cylinder of the diesel engine, and the intake pressure is increased (supercharging).
[0029]
At this time, a large amount of combustion residue, that is, exhaust gas containing a large amount of carbon particles, is discharged from a large diesel engine that is operated using low-quality fuel oil as fuel.
[0030]
For this reason, during operation of the diesel engine, the gas outlet guide tube 3 facing the blade tip as shown by the symbol X in FIG. 1 due to the exhaust gas flowing through the gap δ between the blade tip and the inner surface of the gas outlet guide tube 3. Carbon gradually accumulates on the inner peripheral surface portion of the.
[0031]
Here, it is assumed that a large amount of this carbon is accumulated and the diesel engine is stopped in this accumulated state.
[0032]
Then, the gas outlet guide tube 3 is thermally contracted, and with the contraction, the blade tip is buried in the deposit X accumulated. Then, as shown in FIG. 2A, when the deposit X cools and becomes a lump, the blade tip is fixed.
[0033]
It is assumed that the diesel engine is started from this state.
[0034]
At this time, since the nozzle outer ring 5 is on the upstream side (side closer to the engine) than the gas guide cylinder 3, the nozzle outer ring 5 is heated before the gas outlet guide cylinder 3 by exhaust gas exhausted from the diesel engine. To rise.
[0035]
Here, the nozzle outer ring 5 is fitted to the end of the gas outlet guide tube 3 forming the exhaust gas introduction port 2 so as to fit from the inside.
[0036]
By this fitting, the exhaust gas introduction port is expanded from the inside by the radial thermal expansion displacement generated in the nozzle outer ring 5.
[0037]
The gas outlet guide cylinder 3 is supported by the bracket 8 so that the radial displacement is not restricted from the exhaust gas inlet 2 to the downstream side of the axial turbine 4. Is transmitted to a point where the deposit X exists as shown in FIG. This expansion appears as an action of separating the inner surface of the gas outlet guide tube 3 from the blade tip, that is, a behavior of widening the gap δ with the blade tip.
[0038]
This behavior forces the blade tip to leave the deposit X. Then, the blade tip can come out of the non-rotatable fixed state, and the axial turbine 4 returns to the original rotatable state.
[0039]
As a result, the axial turbine 4 is rotationally driven by the heat energy of the exhaust gas.
[0040]
Therefore, even if the blade tip sticks to the deposit X due to the engine being stopped, the sticking is released due to the thermal expansion displacement of the nozzle outer ring 5 at the initial start of the engine, so that the axial flow turbine 4 remains non-rotatable. Rather, the operation of the original supercharger can be promised and the reliability of the supercharger can be improved.
[0041]
In addition, the burden of cleaning maintenance on the axial turbine 4 and the gas outlet guide tube 3 is reduced.
[0042]
The second embodiment shown in FIG. 3 shows a large diesel engine exhaust gas turbine turbocharger Invite example embodiment.
[0043]
In the present embodiment, the guide for directing the exhaust gas flow inward over the entire inner circumference between the outer periphery of the exhaust gas inlet 2, specifically between the end of the gas outlet guide tube 3 and the nozzle outer ring 5. Adopting a structure in which a ring member 21 having a projection 20 (corresponding to a guide) is provided, exhaust gas from the nozzle outer ring 5 is discharged as shown by the arrow in FIG. 3 during operation of the supercharger. The gap δ between the blade tip and the inner surface of the gas outlet guide cylinder 2 is avoided and guided to the blade 4a so that the exhaust gas containing carbon particles does not flow into the gap δ during operation of the supercharger.
[0044]
When the exhaust gas flow to the gap δ is suppressed in this way, the generation of carbon deposits X that cause sticking of the blade tips is suppressed, and the axial flow turbine is caused by the deposits X deposited on the inner surface of the gas outlet guide tube 3. 4 can be prevented from rotating.
[0045]
Therefore, the operation of the original supercharger can always be performed, and the reliability of the supercharger is improved.
[0046]
In FIG. 3, the ring member 21 having the guide protrusion 20 is used. However, the present invention is not limited to this, and the guide protrusion 20 is formed directly on the inner surface of the gas outlet guide tube 3 or the inner surface of the nozzle outer ring 5. Also good.
[0047]
However, in FIG. 3, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0048]
The third embodiment shown in FIGS. 4 and 5 show a large diesel engine exhaust gas turbine turbocharger Invite example embodiment.
[0049]
In the present embodiment, the gap δ, at the outer peripheral end of the blade 4a, for example, two symmetrical points 180 degrees in the circumferential direction of the turbine 4 that do not impair the rotational balance of the axial turbine 4 as shown in FIG. That is, a structure in which a protrusion 30 protruding toward the inner peripheral surface of the gas outlet guide tube 3 is employed, and carbon deposited on the inner surface portion of the gas outlet guide tube 3 facing the gap δ is protruded during operation of the supercharger. The part 30 is scraped off to suppress the growth of the deposit X.
[0050]
As a result, even if carbon particles are deposited on the inner surface of the gas outlet guide tube 3, the blade 4 a is prevented from sticking, and the axial turbine 4 is caused by the deposit X deposited on the inner surface of the gas outlet guide tube 3. Prevents rotation from becoming impossible.
[0051]
Therefore, the operation of the original supercharger can always be performed, and the reliability of the supercharger is improved.
[0052]
In FIGS. 4 and 5, the example in which the protrusions 30 are provided at the points 180 ° in phase is given, but three or more protrusions 30 may be provided.
[0053]
However, in FIG. 4 and FIG. 5, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0054]
【The invention's effect】
As described above, according to the first aspect of the present invention, it is possible to prevent the axial flow turbine from becoming unrotatable by deposits accumulated on the inner surface of the casing, and to promise the operation of the original supercharger. .
[0055]
Therefore, the reliability of the supercharger can be increased. Moreover, the burden of cleaning maintenance on the axial turbine and the inner surface of the casing can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining the structure of an exhaust gas turbine supercharger according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining a state where a blade tip fixed to a deposit is separated from the deposit due to thermal expansion of a nozzle portion at the initial stage of starting the engine in a cold state.
FIG. 3 is a cross-sectional view for explaining the structure of an exhaust gas turbine supercharger according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view for explaining the structure of an exhaust gas turbine supercharger according to a third embodiment of the present invention.
FIG. 5 is a cross-sectional view taken along line AA in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Turbine side 2 ... Exhaust gas inlet 3 ... Gas outlet guide cylinder (casing)
4 ... Blade 5 ... Nozzle outer ring (nozzle part)
7 ... fitting part 8 ... bracket 20 ... guide protrusion (guide part)
30 ... Projection.

Claims (1)

A cylindrical casing having an exhaust gas inlet at one end, an axial turbine disposed in the casing facing the exhaust gas inlet, and an exhaust gas at the exhaust gas inlet; Comprising a turbine side connected to a nozzle portion for jetting the nozzle to the blade of the axial turbine,
The outer peripheral portion of the casing is supported by a bracket at a point downstream from the position of the axial turbine, and the wall portion where the radial displacement of the casing end forming the exhaust gas inlet faces the tip of the blade To be spread to
The end portion of the nozzle portion is fitted so as to be fitted by a fitting portion formed by a male and female annular step from the casing end forming the exhaust gas introduction portion and from the inside ,
The exhaust gas turbine supercharger is characterized in that a wall portion facing the blade tip of the casing is expanded by a thermal expansion displacement in a radial direction of the nozzle portion transmitted to the casing end.

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