JPH10205340A - Variable displacement turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of damage caused by the vibration of a moving blade by attaching a variable nozzle fixed to a gas entrance flow passage for the rotary-driven moving blade to a nozzle rotary shaft such that its rotational center is positioned in an exit rear end side rather than the particular position of a nozzle from the exit rear end with respect to a nozzle cord length. SOLUTION: A variable nozzle 2 provided in a variable displacement type exhaust turbine supercharger is fixed in the end part of a nozzle rotary shaft and rotated integrally with the nozzle rotary shaft by the operation of a nozzle driving part to change the entrance angle and the passage area of gas. In this case, the nozzle rotary shaft is attached to the variable nozzle 2 such that the rotational center 14a of the variable nozzle 2 is set to the distance L1 -<=1/3L (L is a nozzle cord length) of the variable nozzle 2 from a nozzle exit rear end 4. Thus, when the nozzle rotary shaft and the variable nozzle 2 are rotated, the changing amount of the distance of a nozzle rear end distance ΔR is smallest, the changing amount of a ratio ΔR/WN between the nozzle rear end distance ΔR and a nozzle blade width WN is suppressed small and an increase in the exciting force of a moving blade 7 is limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is applied to an exhaust gas turbine supercharger, a gas turbine, a gas expander, etc.
The present invention relates to a structure of a variable nozzle in a variable capacity turbine that changes a gas flow rate to a turbine blade by rotating a nozzle to change a nozzle blade angle.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show the basic structure of a conventional exhaust gas turbine turbocharger for a diesel engine on the exhaust turbine side, and FIG. 3 is a sectional view taken along the axis of a rotating shaft (rotor). 4 is a view taken in the direction of arrows BB in FIG.

3 and 4, reference numeral 20 denotes a gas inlet casing, 1 denotes a spiral scroll formed in the gas inlet casing 20, 21 denotes a gas outlet casing, and 12 denotes an exhaust diffuser formed in the gas outlet casing 21. Reference numeral 10 denotes a rotating shaft (rotor), and reference numeral 7 denotes a plurality of moving blades fixed to the shaft end of the rotating shaft 10. A compressor (not shown) is fixed to the other end of the rotating shaft 10.

[0004] Reference numeral 2 denotes a variable nozzle provided at a vaneless portion 6 at the entrance of a moving blade 7 at the end of the scroll 1. The variable nozzle 2 is fixed to an end of a nozzle rotation shaft 14, , And changes the inlet angle and passage area of the gas 9. Reference numeral 13 denotes a nozzle driving unit for rotating the nozzle rotation shaft 14.

The variable nozzle 2 has a rotation center, that is, an axis 14a of a nozzle rotation shaft 14, as shown in FIG.
The nozzle code length L, a is attached to the nozzle rotating shaft 14 so that the length of the nozzle outlet trailing edge 4 to the axis 14a in L ₁ /L=0.5 vicinity When L _1.

During operation of such a conventional variable displacement type exhaust turbine turbocharger, exhaust gas discharged from a cylinder of an engine (not shown) turns through the scroll 1 of the gas inlet casing 20 in the circumferential direction thereof. This gives a radial flow velocity, leading to the leading edge 3 of the variable nozzle 2
Through the nozzle 2.

In the variable nozzle 2, the exhaust gas is restricted in its flow path by a nozzle throat portion 5 to increase the flow velocity, flows out from a nozzle outlet trailing edge 4, and passes through a vaneless portion 6 and an inlet leading edge 8 of a moving blade 7. After flowing into the moving blade 7 and passing through the moving blade 7, expansion work is performed and rotation is performed around the rotation axis of the moving blade 7 to generate power, and exhaust is performed through the trailing edge 11 of the moving blade 7. It flows out to the diffuser 12.

In the turbocharger, when changing the gas flow rate to change the driving exhaust energy (exhaust turbine driving horsepower) of the exhaust turbine, the nozzle driving unit 13 is operated to change the driving energy through the nozzle rotating shaft 14. The gas flow rate is adjusted by rotating the nozzle 2 to the axis of the nozzle rotation shaft 14, that is, the nozzle blade angle set around the rotation center 14a, and changing the area of the nozzle throat portion 5, which is the minimum gas passage. I do.

[0009]

In the conventional variable-capacity exhaust gas turbocharger, as shown in FIG.
The nozzle blade angle α in the circumferential direction is the optimum value 2
The design point is around 0 °, and the distance of the vaneless portion 6 between the trailing edge 4 of the nozzle and the leading edge 8 of the moving blade, that is, the trailing edge distance ΔR of the nozzle, is defined as the ratio ΔR / W of this to the nozzle blade width W _{N. N} =
It is set to be around 0.5.

If the code length of the variable nozzle 2 is L,
In this setting, the nozzle blade width W _NO and the nozzle trailing edge distance Δ
R _O is as follows. W _NO = L · Sin20 ° = 0.34202L (1) ΔR _O = 0.5 · W _NO = 0.171010L (2)

Next, when the nozzle vane angle α = about 40 ° corresponding to the maximum flow rate setting, that is, when the trailing edge of the outlet of the variable nozzle 2 is at 4a in FIG. Is L ₁ / L =
0.5, the nozzle trailing edge distance Δ
Relationship R and the nozzle width W _N is as follows.

W _N = L · Sin 40 ° = 0.642788L (3) ΔR = ΔR _O − (0.5 L · Sin 40 ° −0.5 L · Sin 20 °) where ΔR _O = 0.5 L · Sin 20 °. From ΔR = 0.5L · Sin20 ° − (0.5L · Sin40 ° −0.5L · Sin20 °) = 0.020626L (4) Therefore, ΔR / W _N = 0.032089 (5), and the initial set value ΔR / W _N is lower than 0.5.

Here, the nozzle trailing edge distance / nozzle width = Δ
R / W _N and the exciting force P of the rotor blade 7 by the nozzle wake have a relationship as shown in FIG.

[0014] That is, as shown in FIG. 5, the [Delta] R / W _N
Is reduced, that is, as the nozzle outlet trailing edge 4 approaches the bucket blade leading edge, the nozzle wake downstream of the nozzle increases and the blade exciting force P increases. In the case of the prior art, ΔR _O / W _NO = 0.5 at the time of the initial setting is changed to ΔR / W _N at the time of the maximum flow rate setting (α = around 40 °).
= 0.032089, and as shown in FIG. 5, the blade excitation force P is increased to 6 times or more the value at the time of the initial setting. Therefore, there is a possibility that the nozzle blade may be damaged due to nozzle wake resonance.

The present invention has been made in view of the problems of the prior art, and
To provide a variable capacity turbine that prevents the occurrence of damage due to vibration of the moving blades by suppressing an increase in the exciting force due to the nozzle wake in an operating range where the nozzle blade angle at the maximum flow rate or the like is larger than the design point. Aim.

[0016]

In order to solve the above-mentioned problems, the present invention provides a variable nozzle mounted on a nozzle rotating shaft in a gas inlet flow path to a rotating blade which is driven to rotate, and the variable nozzle is connected to a nozzle. A variable capacity turbine configured to change the turbine capacity by rotating the nozzle rotation axis about the axis of the nozzle and changing the blade angle thereof by a driving means, wherein the variable nozzle has a rotation center of the nozzle. A variable displacement turbine, which is attached to the nozzle rotating shaft so as to be located closer to the outlet trailing edge than one-third of the nozzle cord length (L) from the outlet trailing edge.

According to this invention, the variable nozzle is set on the nozzle rotation axis, and the center of rotation is set to L ₁ ≤1 / 3L from the trailing edge of the outlet with respect to the nozzle code length L. Nozzle blade angle (α) set at point
The nozzle trailing edge distance when the variable nozzle is rotated around the rotation center with respect to the nozzle trailing edge distance (radial distance between the nozzle outlet trailing edge and the moving blade separate edge) (ΔR _O ) corresponding to The amount of change in ΔR is reduced.

[0018] Thus, the variation in ratio [Delta] R / W _N of the [Delta] R and nozzle blade width W _N is kept small, it can suppress the increase in the blade excitation force by the nozzle wake, occurrence of nozzle wake resonance , And the occurrence of breakage of the moving blade can be prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

FIG. 1 is a cross-sectional view of a variable displacement type exhaust turbine turbocharger according to an embodiment of the present invention, taken along a rotation axis, and FIG. 2 is a view taken along the line AA of FIG.

1 and 2, reference numeral 20 denotes a gas inlet casing, 1 denotes a spiral scroll formed in the gas inlet casing 20, 21 denotes a gas outlet casing, and 12 denotes an exhaust diffuser formed in the gas outlet casing 21. Reference numeral 10 denotes a rotating shaft (rotor), and reference numeral 7 denotes a plurality of moving blades fixed to the shaft end of the rotating shaft 10. The rotating shaft 10
A compressor (not shown) is fixed to the other end.

Reference numeral 2 denotes a variable nozzle provided at a vaneless portion 6 at the end of a moving blade 7 at the end of the scroll 1. The variable nozzle 2 is fixed to an end of a nozzle rotation shaft 14, and is connected to the nozzle rotation shaft 14. By rotating together, the inlet angle and passage area of the gas 9 are changed. Reference numeral 13 denotes a nozzle driving unit for rotating the nozzle rotation shaft 14. The above configuration is the same as in the prior art.

In the embodiment of the present invention, the nozzle rotation shaft 14 for changing the nozzle vane angle of the variable nozzle 2 has its axis center, that is, the rotation center 14 a of the variable nozzle 2 positioned from the nozzle outlet trailing edge 4 of the variable nozzle 2. When attached to the variable nozzle 2 so that the distance L ₁ ≦ １ ／ L (L is the length of the nozzle cord) and the nozzle rotation shaft 14 and the variable nozzle 2 are rotated, the distance of the nozzle trailing edge distance ΔR is The configuration is such that the amount of change is minimized.

The basis for setting the position of the rotation center 14a of the variable nozzle with respect to the variable nozzle 2, that is, for setting L ₁ ≤1 / 3L, is as follows.

In FIG. 5, the point at which the exciting force P by the nozzle wake suddenly rises (increases) is the ratio of the nozzle trailing edge distance ΔR to the nozzle blade width W _N , ie, the dimensionless nozzle trailing edge distance ΔR / W _N. = 0.11. Therefore, assuming that the axis 14a of the nozzle rotating shaft 14 is attached to a point 1 / χ of the nozzle cord length L, ΔR / W _N = {ΔR _O- (X · Sin40 ° −X · Sin20 °)} / W _N (6) Here, X = L / χ.

Further, as shown in the above equations (2) and (3), ΔR _O = 0.5 W _NO = 0.171010 L W _N = 0.642788 L, so that these and ΔR / W _N = 0.11 Substituting into equation (6) and rearranging, 0.11 = {0.171010L− (0.300768) L / χ｝ /0.642788L} = 0.300768 / 0.100302 = (about) 3 (7)

Therefore, from the equation (7), the rotation center 14
If a is attached at a position smaller than 1 / χ of the nozzle cord length L, that is, 1/3, that is, closer to the outlet trailing edge 4, the excitation force P becomes smaller.

However, as described above, the center of rotation 14a of the variable nozzle 2 is closer to the trailing edge 4 of the nozzle outlet than 1/3 of the nozzle cord length L, and the closer to the trailing edge 4, the smaller the exciting force P becomes. It becomes, but since the bending moment increases applied to that amount nozzle 2, the mounting position L ₁ 1/3
It is preferable to be near L.

During operation of the variable displacement type exhaust gas turbine turbocharger having the above configuration, the engine (not shown) is used.
Exhaust gas discharged from the cylinder passes through the scroll 1 of the gas inlet casing 20 and is swirled in the circumferential direction to be given a radial flow velocity, into the nozzle 2 through the inlet front edge 3 of the variable nozzle 2. Inflow.

In the variable nozzle 2, the exhaust gas is throttled at the nozzle throat portion 5 to increase the flow velocity by flowing through the nozzle outlet trailing edge 4, and flows out of the vaneless portion 6 and the inlet leading edge 8 of the moving blade 7. After flowing into the moving blade 7 through the moving blade 7, expansion work is performed and the moving blade 7 is rotated around the rotation axis 10 to generate power, and exhausted through the trailing edge 11 of the moving blade 7. It flows out to the diffuser 12.

In the supercharger, when the driving exhaust energy (exhaust turbine driving horsepower) of the exhaust gas turbine is changed by changing the gas flow rate, the nozzle driving unit 13 is operated through the nozzle rotating shaft 14. The gas flow rate is adjusted by rotating the variable nozzle 2 to a nozzle blade angle α set around the rotation center 14 a of the nozzle rotation shaft 14 and changing the area of the nozzle throat portion 5 which is the minimum gas passage.

The variable nozzle 2 has a nozzle rotation center 14.
2, the nozzle outlet trailing edge 4 moves from the position 4a of the maximum nozzle blade angle to the position 4b of the minimum nozzle blade angle, as shown in FIG. Since the position is set to L ₁ ≦ 1 / 3L,
The amount of change in the nozzle trailing edge distance ΔR becomes smaller with respect to the nozzle trailing edge distance ΔR _O (position of the nozzle outlet trailing edge 4) corresponding to the nozzle blade angle α set at the design point.

Therefore, even if the nozzle blade angle α increases, the aforementioned Δ
R and the amount of change in the nozzle blade width ΔR / W _N are kept small,
It is possible to suppress an increase in the exciting force P of the bucket 7 due to the nozzle wake.

[0034]

As described above, according to the present invention, since the center of rotation of the variable nozzle is set closer to the outlet trailing edge than one-third of the nozzle cord length from the trailing edge of the nozzle outlet, the variable nozzle is designed at the design point. The amount of change in the trailing edge distance of the nozzle when the nozzle is rotated from is reduced.

Thus, the nozzle trailing edge distance (ΔR)
And the amount of change in the ratio ΔR / W _N between the nozzle blade width (W _N ) and the nozzle blade width (W _N ) can be suppressed to a small value, and an increase in the exciting force of the blade due to the nozzle wake can be suppressed. The occurrence of breakage can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view along a rotation axis of a variable displacement type exhaust turbine turbocharger according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a diagram corresponding to FIG. 1 of a variable displacement type exhaust gas turbine supercharger according to the related art.

FIG. 4 is a view taken in the direction of arrows BB in FIG. 3;

FIG. 5 is a diagram showing a change in an exciting force by a nozzle wake in a variable nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Scroll 2 Variable nozzle 4, 4a, 4b Nozzle outlet trailing edge 5 Nozzle throat part 6 Vaneless part 7 Moving blade 10 Rotary shaft 12 Exhaust diffuser 13 Nozzle drive part 14 Nozzle rotary shaft 14a Nozzle rotary shaft center 20 Gas inlet casing 21 Gas outlet casing

Claims (1)

[Claims] 1. A variable nozzle attached to a nozzle rotating shaft is provided in a gas inlet flow path to a rotating blade that is driven to rotate, and the variable nozzle is rotated around the axis of the nozzle rotating shaft by nozzle driving means. In the variable capacity turbine configured to change the turbine capacity by changing the blade angle of the variable nozzle, the variable nozzle has a rotation center whose rotation center is equal to one of the nozzle cord length (L) from an outlet trailing edge of the nozzle. The variable displacement turbine is mounted on the nozzle rotation shaft so as to be located closer to the outlet trailing edge than // 3.