JPH116439A - Variable displacement turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable displacement turbine having slide part, preventing leakage through an exhaust gas flow passage, and simple in structure. SOLUTION: A bag body 8 the volume of which is variable through input and output of fluid to vary the sectional area of an exhaust gas flow passage is contained in a turbine housing 1. In this variable displacement turbine, since the bag body 8 to change a volume to vary the sectional area of the exhaust gas flow passage 6 does not have a slide part which a conventional link mechanism is provided, a problem on wear of a slide part in high temperature exhaust gas does not arise. Further, since the sectional area of a flow passage is throttled or expanded by changing the volume of the bag body 8, a space formed on the back side of a conventional moving plate is not formed and no exhaust gas flows therein, whereby incurring of a loss is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a variable capacity turbine.

[0002]

2. Description of the Related Art A variable capacity turbine used for an exhaust supercharger (turbocharger) of a vehicle changes a flow angle of exhaust gas to a turbine wheel by a vane or changes a cross-sectional area of an exhaust gas flow path toward the turbine wheel. By changing the range, the operating range of the turbocharger is expanded to eliminate the so-called turbo lag.

[0003] As such a variable capacity turbine, a plurality of movable vanes are provided at predetermined intervals in a circumferential direction so as to surround a turbine wheel in a turbine housing, and the angles of these movable vanes are changed by a link mechanism. It is known that a moving plate is provided in an exhaust gas flow passage in a housing to partition the flow passage in a longitudinal direction, and the moving plate is moved to change a substantial cross-sectional area of the flow passage.

[0004]

However, since the movable vanes and moving plates described above operate in high-temperature exhaust gas,
Wear problems arise. That is, the movable vanes, the link mechanisms thereof, the sliding portions of the movable plate, and the like are repeatedly operated in a state where the temperature becomes high due to the exhaust gas, so that wear occurs at those portions. For this reason, it is necessary to use a material excellent in abrasion resistance at a high temperature or to perform a surface treatment, which is costly.

In addition, between the movable vane and the inner surface of the turbine housing, and between the movable plate and the inner surface of the turbine housing,
Since it is necessary to provide a predetermined clearance for movement, exhaust gas leaks from the clearance, causing loss,
Turbine efficiency deteriorates. In particular, in the case of the moving plate method, since a space is formed on the back side of the moving plate disposed in the exhaust gas flow path, the exhaust gas flows into the space through the clearance, causing a large loss.

In addition, the movable vane system and the moving plate system both have complicated mechanisms, and there has been a problem that the cost is increased for ensuring reliability.

An object of the present invention, which has been made in view of the above circumstances, is that there is no sliding portion, no leakage from the exhaust gas flow path,
Another object of the present invention is to provide a variable capacity turbine having a simple structure.

[0008]

In order to achieve the above object, a variable capacity turbine according to the present invention has a bag whose volume changes by taking in and out a fluid in a turbine housing so as to make a sectional area of an exhaust gas flow path variable. The body is housed.

According to the present invention, since the bag which changes in volume so as to make the cross-sectional area of the exhaust gas flow path variable does not have a sliding portion as in the conventional link mechanism, the sliding portion in the high-temperature exhaust gas does not have a sliding portion. No wear problems occur.

Further, since the cross-sectional area of the flow path is reduced or expanded by changing the volume of the bag body, there is no space formed on the rear side of the conventional moving plate, and exhaust gas flows into the space. Since there is no such, the loss can be reduced.

[0011] The bag body may be formed of a metal bellows formed in a beveled shape so as to surround the turbine wheel, and the metal bellows may expand and contract in the axial direction of the turbine wheel.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a side sectional view of a variable displacement turbine according to this embodiment. As shown, a turbine wheel 2 is rotatably accommodated in a turbine housing 1 into which exhaust gas from an engine is introduced. The turbine wheel 2 is connected to a compressor wheel via a rotating shaft 3 that is supported by a center housing (not shown). The compressor wheel is housed in the compressor housing and pressurizes intake air toward the engine.

As shown in FIG. 2, the turbine housing 1 is formed in a scroll shape so as to surround the turbine wheel 2, and an inlet 4 into which exhaust gas of the engine is introduced is formed at one end thereof in a tangential direction. An outlet 5 for discharging the exhaust gas is formed at the center in the axial direction. The exhaust gas introduced from the inlet 4 is accelerated through an exhaust gas channel 6 formed in a scroll shape in the turbine housing 1,
The gas flows into the turbine blade 7 to rotate the turbine wheel 2 and is discharged from the outlet 5.

As shown in FIG. 1, the turbine housing 1 is formed in a scroll shape and accommodates a turbine wheel 2 and has a beveled opening on the outlet 5 side, and an opening of the housing body 1a. And a lid member 1b for covering the portion. A metal bellows 8 is attached to the lid member 1b as a bag whose volume changes by taking in and out of a fluid. As shown in FIG. 2, the metal bellows 8 is formed in a round shape so as to surround the turbine wheel 2, and a metal that is hardly deteriorated even when exposed to high-temperature exhaust gas is used as a material thereof.

The metal bellows 8 has a rear surface portion 8a formed in the shape of an oblique plate and attached to the lid member 1b, and a rear surface portion 8a.
And a bellows portion 8c connecting the front surface portion 8b and the back surface portion 8a. The bellows portion 8c is expanded or folded. As a result, the turbine wheel 2 expands and contracts in the axial direction. A gap 10 is formed between the bellows portion 8c and the inner surface 9 of the housing body 1a facing the bellows portion 8 so as not to hinder the metal bellows 8 from expanding and contracting. As shown in FIG. 2, the metal bellows 8 is formed with a slope 8 d facing the inlet 4 of the turbine housing 1 to reduce exhaust gas resistance.

The metal bellows 8 is connected to a pipe 11 through which a fluid (air, water, oil, etc.) flows in and out. When a fluid flows into the metal bellows 8 from the pipe 11, the bellows portion 8c is developed, the metal bellows 8 expands in the axial direction of the turbine wheel 2, and the cross-sectional area of the exhaust gas passage 6 decreases. At this time, an interval 12 for preventing contact is set between the metal bellows 8 and the turbine blade 7. Conversely, pipe 11
If the fluid in the metal bellows 8 flows out from the bellows 8
c is folded and the metal bellows 8 is
, And the cross-sectional area of the exhaust gas channel 6 increases.

FIG. 3 shows the expansion and contraction of the metal bellows 8 as viewed from the inlet 4 side of the turbine housing 1. FIG.
In the figure, 13a is a flange to which an exhaust pipe from the engine is connected, and 13b is a mounting hole.

The operation of this embodiment having the above configuration will be described.

The capacity of the turbine is determined by the turbine wheel 2
When the (turbine blade 7) is common, it is determined by A / R. A / R is, as shown in FIG. 4, the cross-sectional area A of the exhaust gas flow path 6 in the turbine housing 1 and the radius R from the center of the rotation axis of the turbine wheel 2 to the area center of gravity of the flow-path cross-sectional area A. Is the ratio of

In the variable displacement turbine according to the present embodiment, when the metal bellows 8 expands in the axial direction of the turbine wheel 2, the cross-sectional area A of the exhaust gas flow path 6 becomes smaller, and A /
R decreases, and conversely, when the metal bellows 8 contracts in the axial direction of the turbine wheel 2, the cross-sectional area A of the exhaust gas flow path 6 increases and A / R increases.

As shown in FIG. 5, the capacity of the turbine changes such that the flow parameter increases as the A / R increases, and the flow parameter decreases as the A / R decreases. Therefore, by appropriately expanding and contracting the metal bellows 8 according to the operating state of the engine to change the A / R, the operating range of the supercharger can be expanded, and the so-called turbo lag can be reduced.

Here, since the variable capacity turbine uses a metal bellows 8 whose volume changes depending on the flow of fluid, the cross-sectional area of the exhaust gas passage 6 is variable. Since there is no sliding portion as in the moving plate type, the problem of abrasion of the movable sliding portion in high-temperature exhaust gas, which has conventionally been a problem, does not occur at all. Therefore, the durability and reliability are improved in combination with the simple configuration of the device, and the cost is reduced.

In the variable displacement turbine, the cross-sectional area of the exhaust gas passage 6 is reduced or expanded by changing the volume of the metal bellows 8, so that the rear side of the moving plate is different from the conventional moving plate system. There is no space formed in the space, and the loss due to the exhaust gas flowing into the space can be reduced. As a result, no large leakage of the exhaust gas from the exhaust gas channel 6 occurs, and the turbine efficiency can be improved.

That is, the variable capacity turbine of the present embodiment expands and contracts the metal bellows 8 attached to one side surface (the inner surface of the lid member 1b) of the exhaust gas passage 6 to reduce the substantial sectional area of the exhaust gas passage 6. Since the moving plate that separates the exhaust gas flow path in the longitudinal direction is not moved to change the substantial exhaust gas flow path cross-sectional area as in the conventional case, the space into which the exhaust gas flows as in the conventional case is not changed. Is the exhaust gas channel 6
There is no room within.

However, even in the variable capacity turbine according to the present embodiment, the gap 10 between the bellows portion 8c of the metal bellows 8 and the inner surface 9 of the housing main body 1 facing the bellows portion 8c Is partially invaded, but the gap 1
Since the volume of 0 is extremely small, it does not cause a serious problem that the turbine efficiency is deteriorated.

The expansion and contraction of the metal bellows 8 are as follows:
Since the bellows portion 8c expands and contracts in the axial direction of the turbine wheel 2 and the distance between the front surface portion 8b and the back surface portion 8a changes substantially in parallel, an excessive force is applied to the metal bellows 8 during expansion and contraction. No bellows 8 are wrinkled. Further, since a predetermined interval 12 is set between the metal bellows 8 and the turbine blade 7 as shown in FIG. 1, no contact occurs between them.

It is to be noted that the pipe 11 may be provided as a single pipe and used for both inflow and outflow, or a plurality of pipes may be provided as shown by phantom lines in FIG. When the balanced expansion and contraction of the metal bellows 8 cannot be achieved with only one pipe 11, fluid may flow in or out of the plurality of pipes 11, 11,... At the same time.

Further, the metal bellows 8 is divided into a plurality of independent bellows pieces in the circumferential direction as shown by the imaginary line 14, and pipes 11 are provided respectively, and the amount of expansion and contraction of each bellows piece is independently controlled by each pipe 11. It may be changed. in this case,
By making the amount of expansion and contraction of each bellows piece equal, and by making the amount of expansion and contraction different, the interval between the surface portion 8b of each bellows piece and the inner surface 15 of the housing body 1 facing the same can be reduced. It may be gradually narrowed or widened along the road 6.

Another embodiment of the present invention is shown in FIGS.

As shown in the figure, in this embodiment, the metal bellows 8 is mounted on a radially outer inner surface 16 of the turbine housing 1, and the metal bellows 8 is expanded and contracted radially inward to cut off the exhaust gas passage 6. The area is changed.

The metal bellows 8 includes an outer peripheral portion 8e attached to a radially outer inner surface 16 of the turbine housing 1 and an inner peripheral portion 8f arranged so as to face the exhaust gas flow path 6 in parallel with the outer peripheral portion 8e. The inner peripheral portion 8f and the outer peripheral portion 8
e and a bellows portion 8g for connecting to the turbine wheel 2 when the bellows portion 8g is expanded or contracted in the radial direction of the turbine wheel 2 (see FIG. 7).

A gap is formed between the bellows portion 8g and the inner surface 17 of the housing body 1 facing the bellows portion so as not to hinder the expansion and contraction of the metal bellows 8. In addition, the metal bellows 8 is formed with a slope 8h facing the inlet 4 of the turbine housing 1 to reduce exhaust gas resistance.

Also in this embodiment, the metal bellows 8
The A / R can be changed by causing fluid to flow in and out of the pipe 11 to expand and contract the metal bellows 8 in the radial direction.

As in the previous embodiment, there is no problem of abrasion due to the absence of a sliding portion, no loss due to leakage from the exhaust gas passage 6, and a high durability and reliability with a simple structure. Of course, it is.

Further, the metal bellows 8 is divided into a plurality of independent bellows pieces in the circumferential direction as shown by the imaginary line 18, and pipes 11 are provided respectively, and the amount of expansion and contraction of each bellows piece is independently controlled by each pipe 11. It is the same as in the previous embodiment that it may be changed.

[0037]

As described above, according to the variable displacement turbine of the present invention, the following effects can be obtained.

(1) The capacity can be varied with a simple configuration.

(2) Since there is no sliding portion, there is no problem of wear.

(3) Since there is no large leakage from the exhaust gas passage, the turbine efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a variable capacity turbine according to an embodiment.

FIG. 2 is an explanatory view showing a turbine housing and a bag body of the variable capacity turbine.

FIG. 3 is a view taken along line III-III of FIG. 2;

FIG. 4 is a partial side sectional view of a turbine.

FIG. 5 is a diagram showing flow characteristics.

FIG. 6 is an explanatory diagram of a variable capacity turbine according to another embodiment.

FIG. 7 is a view taken along line VII-VII of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine housing 6 Exhaust gas flow path 8 Metal bellows as bag 8c Bellows

Claims (3)

[Claims] 1. A variable capacity turbine in which a bag body whose volume changes by taking in and out of a fluid is accommodated in a turbine housing so that a cross-sectional area of an exhaust gas passage is variable. 2. The variable displacement turbine according to claim 1, wherein said bag body is formed of a metal bellows formed in a shape of a jewel so as to surround a turbine wheel. 3. The variable displacement turbine according to claim 2, wherein the metal bellows expands and contracts in an axial direction of a turbine wheel.