JPH0439391Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to turbine devices such as gas turbines and turbochargers.

[Prior Art] Generally, a gas turbine or a turbocharger has an axial flow type or radial type turbine rotor integrated with a rotating shaft, and its high speed rotation rotates a coaxial compressor to obtain high pressure air.
(For example, see Japanese Utility Model Application Publication No. 58-72427.) [Problems to be solved by the invention] By the way, the blades and disks of the turbine rotor, which are rotationally driven by high-temperature gas, reach extremely high temperatures and are exposed to the lubricating oil atmosphere. The internal shaft (rotating shaft) is relatively low temperature although heat is conducted from the disk, so a large temperature gradient occurs in the continuous area between the disk and the shaft. As a result, large thermal stresses are generated within the turbine rotor material, with the higher elongation at higher temperatures pulling the lower regions.

That is, in FIG. 2, the radial turbine rotor 3 is in the driving gas H atmosphere, and the shaft 4 is in the lubricating oil L atmosphere. Both are integrally connected by a continuous portion 5. The continuous portion 5 is located on the back side of the disk 6 and has a plurality of blades 7 on the other side of the disk 6. Further, a groove 17 for a seal ring is provided in the shaft 4 by cutting. In such a turbine rotor, the thermal stress at part A on the back surface of the disk 6 is σ _A , the thermal stress at the central part B of the disk 6 is σ _B ,
The end of the ring groove 17 is M, the base of the disk 6 is N, the temperature of the M part is T _M , the temperature of the N part is T _{N, T N -} T _M =
Assuming ΔT (temperature difference), the thermal stress generated in the turbine rotor varies depending on the temperature of the turbine rotor driving gas H, gas flow rate, lubricating oil temperature, and oil amount, but it is the cause of turbine rotor destruction. The large tensile thermal stress occurs mainly in parts A and B, and the stress values σ _A and σ _B are determined by the temperature difference ΔT.
As a result of analysis using the finite element method, it was found that the

Figures 3 and 4 show the tensile thermal stress and temperature difference ΔT of a turbocharger rotor for a 2-class engine.
FIG. 3 is for a metal rotor, and FIG. 4 is for a ceramic rotor. As is clear from these figures, the problematic thermal stress is approximately proportional to the temperature difference ΔT, and if this is reduced by 20%, the thermal stress will also be reduced by 20%, and the M and N of the continuous portion 5 will be reduced by 20%.
It is extremely closely related to the temperature difference between the temperatures, that is, the temperature gradient.

In addition to the above-mentioned thermal stress, centrifugal stress due to rotation is added to the turbine rotor, and a combined stress of these superimposed stresses acts on the turbine rotor.Of this combined stress, tensile stress determines the destruction and lifespan of the turbine rotor. . Therefore, it can be said that reducing the thermal stress is as important as reducing centrifugal stress.

As described above, in the case of turbine equipment, a large temperature gradient occurs in the continuous part between the disk and the shaft, which causes a large tensile thermal stress in the material of the turbine rotor disk, which shortens the life of the turbine rotor. The dot was hot.

It is also possible to cool this thermally stressed portion, but if cooling passages and the like are not taken into account, there is a possibility that the turbine device will become larger.

This idea was created as a result of an analysis of the temperature gradient and thermal stress of the rotor disk. It prevents large temperature gradients from occurring in the connection area, extends the life of the turbine rotor, and makes it more compact. The goal is to achieve this with the device.

[Means for Solving the Problems] In order to achieve the above object, this invention includes a turbine rotor in which blades and disks are integrally formed with a shaft, a turbine housing that houses the turbine rotor, and a bearing member for the shaft. In the turbine device, an annular heat insulator is interposed between the disk back surface of the turbine rotor and the bearing housing, and an annular heat insulator is provided between the heat insulator and the bearing housing. form a space,
A boss portion, which bends the outer peripheral side of the heat insulator toward the bearing housing, is sandwiched between the mounting flange of the turbine housing and the bearing housing. An air introduction hole for introducing cooling air into the space is provided, and an air outlet is provided near the inner peripheral end of the heat insulator, facing near the continuous portion between the shaft and the back surface of the disk, and communicating with the annular space. It was established.

[Function] In a turbine device having such a configuration, cooling air is introduced into the annular space from the air introduction hole on the outer circumference of the heat insulator, and this air flows into the air near the inner circumference side end of the heat insulator. The water flows out from the spout to the vicinity of the continuous part between the back surface of the disk and the shaft, and the continuous part is forcibly cooled. Therefore, during the drive rotation of the turbine rotor, a large temperature gradient tends to occur in the continuous section due to the temperature difference between the disk and the shaft, but the temperature difference in the continuous section, which is severe in terms of stress, is reduced. Therefore, temperature gradients and the generation of thermal stress based thereon can be suppressed.

[Example] Examples of this invention will be described below.

FIG. 1 is a diagram showing an embodiment of this invention applied to a turbocharger. First, let me explain the configuration.
The turbine 1 has a radial turbine rotor 3 driven by high-temperature engine exhaust gas passing through a scroll 10 of a turbine housing 2 . The turbine rotor 3 is integral with a rotating shaft 4 and connected to a disk 6 at a continuous portion 5. A plurality of blades 7 are integrally molded on the disk 6 in the radial direction, and the left side thereof becomes the back surface of the disk to form a continuous portion 5. The bearing housing 8 is connected to the shaft 4
is supported via a bearing member 9, and its mounting flange 2a is attached to the turbine housing 2.
are fastened with bolts and nuts 12 via a ring-shaped plate 11.

An annular heat insulator 16 is interposed between the back surface of the disk 6 of the turbine rotor 3 and the bearing housing 8 and serves to shield the bearing member 9 from the heat of the rotor-driving high-temperature gas. The heat insulator 16 includes a cylindrical portion 31 that is close to the inner circumferential surface of the turbine housing 2 and bent in the direction of the bearing housing 8, and a disk portion 32 that is close to the back surface of the disk 6. A boss 33 is formed at the end of the cylindrical portion 31 on the bearing housing 8 side.
The heat insulator 16 is fixed by being sandwiched between the inner circumferential side step portion 2b of the mounting flange 2a of the turbine housing 2.

The heat insulator 16 forms an annular space 22 in contact with the extension 13 of the bearing housing 8 into which air is introduced, and also forms an air outflow gap 34 in contact with the back surface of the disk 6. A flange inner hole 2c as an air introduction hole is formed in the mounting flange 2a of the turbine housing 2, and a pipe 21 is attached to this flange inner hole 2c. The flange inner hole 2c communicates with a boss inner hole 26 as an air introduction hole formed in the boss 33 of the heat insulator 16. Therefore, the annular space 22 includes the pipe 21, the flange inner hole 2c, and the boss. Through the bore 26 cooling air (which may be pump pressurized air or engine compressed air) is introduced.

Further, in the vicinity of the inner peripheral end of the heat insulator 16, openings are provided facing the back surface of the disk 6 in the vicinity of the continuous portion 5, and are arranged in two rows in the radial direction.
A plurality of air jet ports 24 are bored in the circumferential direction. The air outlet 24 communicates the annular space 22 with the air outflow gap 34, and is arranged to be substantially perpendicular to the cross-sectional curve near the continuous portion 5. Further, the heat insulator 16 and the extension part 13 face each other near the shaft of the continuous part 5 so that the annular space 22 gradually narrows toward the inner circumferential side, and the heat insulator 16 and the extension part 13 have a narrow circumferential gap (a continuous air injection 25, which can be said to be an exit.

In addition, in the figure, 18 is a lubricating oil passage, 19 is an oil hole,
20 is a lubricating oil release space, and a compressor is provided on the left side of the shaft 4. Seal ring 15
The continuous portion 5 is in contact with the inner peripheral portion of the extension portion 13 of the bearing housing 8 for sealing lubricating oil.
It is fitted into the shaft groove 17 of.

Next, the action will be explained.

When the high-temperature gas flows in the direction of the arrow, it drives the turbine rotor 3 and compresses the air taken into the engine by a compressor on the left (not shown). The shaft 4 is lubricated by lubricating oil from the lubricating oil passage 18 and the oil hole 19 and rotates at high speed within the bearing member 9. For this reason, the turbine rotor 3 is kept at a high temperature, and the shaft 4 is kept at a significantly low temperature due to the lubricating oil, and the temperature difference between the two causes a large temperature gradient in the continuous portion 5, which prevents the generation of considerable thermal stress.

However, in this embodiment, the cooling air supplied from the pipe 21 flows into the annular space 22 through the flange inner hole 2c and the boss inner hole 26, and the cooling air flows through the air outlet 24.
Since the air is blown from the circumferential gap 25 to the vicinity of the continuous portion 5 of the turbine rotor 3, the continuous portion 5 is forcibly cooled and maintained at a substantially constant intermediate temperature. As a result, the continuous portion 5, which is subject to severe stress,
There is no large temperature gradient and therefore no large thermal stress is generated.

In other words, in the continuous portion 5, the rapid cooling caused by the lubricating oil is alleviated by the air cooling by the air jet ports 24 and the circumferential gap 25, and the thermal stress is reduced accordingly. It goes without saying that the cooling effect of this cooling air can be adjusted by adjusting the flow rate of the cooling air supplied. Note that the air that has been cooled flows away together with the high-temperature gas from the turbine 1.

Further, in this embodiment, the flange inner hole 2c is provided in the mounting flange 2a of the turbine housing 2 as an air introduction hole for introducing cooling air into the annular space 22, and the flange inner hole 2c is provided in the boss 33 on the outer peripheral side of the heat insulator 16. Since the boss inner holes 26 are provided, and the air jet ports 24 and the circumferential gap 25 are provided near the inner peripheral end of the heat insulator 16, the passage path of the cooling air in the annular space 22 is shortened. The amount of heat received from the turbine housing 2 and the bearing housing 8 until the cooling air is released to the continuous section 5 is small, and the cooling performance for the continuous section 5 is improved.

Further, by shortening the cooling air passage, it is possible to reduce ventilation resistance and downsize housing parts such as the bearing housing 2.

In addition, in the above embodiment, even after the engine suddenly stops,
By continuing to flow cooling air for the required time, it is possible to solve the problem of so-called heat soak back, such as seizure of the bearing due to residual heat.

[Effect of the invention] As explained above, according to this invention,
An annular space is formed between the heat insulator and the bearing housing to introduce cooling air, and through this annular space, air is connected to the shaft and the disk from the air outlet at the inner end of the heat insulator. Since the cooling air is blown toward the shaft and the back surface of the disk near the continuous section, the vicinity of the continuous section is forcibly cooled, the temperature gradient is alleviated, and the thermal stress generated in the turbine rotor can be significantly reduced.

In addition, an air introduction hole for introducing cooling air into the annular space is provided in the mounting flange of the turbine housing and a boss portion of the heat insulator, and an air outlet is provided near the inner peripheral end of the heat insulator.
Because they are provided separately, it is possible to shorten the passage path of cooling air from the air inlet to the air outlet, and this reduces the amount of heat received from the turbine housing and bearing housing before the cooling air is released to the continuous part. The cooling performance for continuous parts is improved.

Furthermore, by shortening the cooling air passage, it is possible to reduce ventilation resistance and downsize housing parts such as the bearing housing 2.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of this invention.
Figure 2 is a longitudinal cross-sectional view of the rotor showing locations with severe thermal stress values, Figure 3 is a tensile thermal stress performance diagram against temperature differences for a metal rotor, and Figure 4 is a diagram for a ceramic rotor. be. Explanation of the symbols appearing in the drawings, 2...Turbine housing, 2a...Mounting flange, 2c...Flange inner hole (air introduction hole), 3...Turbine rotor,
4... Shaft (rotating shaft), 5... Continuous part, 6... Disk, 7... Blade, 8... Bearing housing, 16... Heat insulator, 22...
Annular space, 24...Air outlet, 25...Circumferential gap (air outlet), 26...Boss inner hole (air introduction hole), 33...Boss.

Claims (1)

[Claims for Utility Model Registration] A turbine device having a turbine rotor in which blades and disks are integrally formed with a shaft, a turbine housing that houses the turbine rotor, and a bearing housing that supports the shaft via a bearing member. , an annular heat insulator is interposed between the disk rear surface of the turbine rotor and the bearing housing to form an annular space between the heat insulator and the bearing housing, and a mounting flange of the turbine housing and A boss portion with the outer peripheral side of the heat insulator bent toward the bearing housing is sandwiched between the bearing housing and cooling air is introduced into the annular space from outside the turbine housing through the boss portion and the mounting flange. The heat insulator is characterized in that an air inlet hole is provided near the inner circumferential end of the heat insulator, and an air jet port is provided near the inner peripheral end of the heat insulator, facing near the continuous portion between the shaft and the back surface of the disk and communicating with the annular space. Turbine equipment.