JPH0114738Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a gas bearing sealing device for supercharged air, and more particularly to a gas bearing sealing device for a turbocharger that protects the gas bearing from exhaust gas supplied for driving a turbine. .

Gas bearings or air bearings are bearings that use air as a medium instead of lubricating oil in normal bearings, so compared to bearings that use lubricating oil, they have extremely low friction loss and are free from problems associated with lubricating oil (carbon bridges). If the technology is established, it will be extremely effective for high-speed rotating shafts such as those of exhaust gas turbine superchargers. By the way, when air bearings are used in turbochargers, the seals between the turbine and the bearings and between the bearings and the compressor do not have the problems of lubricating oil leaking into the compressor or turbine, unlike bearings that use lubricating oil. Therefore, there is no need for piston rings or carbon face mechanical seals, but on the other hand, simple non-contact type seals with no sliding friction loss are often used, and in that case it is impossible to obtain a perfect seal.

On the other hand, the air bearing of a turbocharger does not need to be supplied with air from the outside, but instead uses the dynamic pressure generated by slowing down the airflow that occurs between the shaft and the bearing surface as the shaft rotates. A hydrodynamic air bearing is used to support the shaft. For this reason, when the engine load increases and the pressure of the combustion exhaust gas entering the turbocharger turbine increases, a portion of the high-temperature combustion exhaust gas leaks into the bearing compartment (nearly atmospheric pressure) through the seal. It comes. For high temperature combustion exhaust gas,
Carbon and sludge are included, so if the carbon and sludge in the exhaust gas that enters the bearing compartment adheres to the bearing surface, the bearing surface will easily wear due to the small bearing clearance, causing the bearing to deteriorate. The lifespan and durability of the product will be reduced.

The present invention was developed by focusing on the above-mentioned conventional problems.The purpose of the present invention is to prevent combustion exhaust gas from leaking from the turbine to the bearing casing, and to scavenge the leaked combustion exhaust gas. An object of the present invention is to provide a gas bearing sealing device for a supercharger that can protect the gas bearing surface from carbon and sludge in combustion exhaust gas and improve the durability and reliability of the gas bearing.

The configuration of the present invention to achieve the above object is to provide a supply system for supplying a part of the discharged pressure air from the compressor as seal gas to the gas bearing part that pivotally supports the shaft that connects the turbine and the compressor. Gas relief ports are formed at both ends of the bearing casing, and the pressure in the bearing casing is increased by the pressure air supplied from the supply system to the gas bearing part of the bearing casing, allowing combustion exhaust gas to flow from the turbine to the bearing casing. It is characterized by preventing leakage and scavenging the leaked combustion exhaust gas together with pressurized air from the relief port.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an external view of the supercharger, and FIG. 2 is a diagram showing its seal gas system. In Figure 1, 1
is a turbine casing, 2 is a compressor casing,
The space between these is airtightly connected to the cylindrical bearing chamber 3. The turbine casing 1 and the compressor casing 2 have a turbine 4 and a compressor 5 shown in FIG.
are accommodated in each. The turbine 4 and the compressor 5 are connected by the same shaft 6, and the rotation of the turbine 4 is transmitted to the compressor 5 via the shaft 6. The shaft 6 is arranged along the axis of the bearing chamber 3, and a thrust collar 7 that supports the thrust load applied to the shaft 6 is provided at the center of the shaft 6, and this is supported by a thrust bearing 8. . Furthermore, journal bearings 9 are provided on both sides of the thrust collar 7 of the shaft 6, respectively, in order to support the radial load of the shaft 6. The journal bearing 9 is
It is supported from the inner wall of the bearing chamber 3 via a spring 10 and a pivot 11. At both ends of the shaft 6, labyrinth packings 12, 12 are provided for sealing between the turbine casing 1, the compressor casing 2, and the bearing casing 3, respectively.

Further, an outlet 13 for taking out a small amount of air discharged from the compressor 5 is formed in the outlet of the compressor compartment 2 or in a part of the scroll. On the other hand, in order to introduce the discharged air taken out from the outlet 13 into the bearing casing 3, an inlet 14 is formed in the thrust bearing 8 portion of the bearing casing 3, and an inlet 14 is formed between the outlet 13 and the inlet. An air introduction pipe 15 is provided to communicate with the air intake pipe 14. The air introduction pipe 15 is made of a pressure-resistant hose, and the air introduction pipe 15 is provided with a throttle valve 16 for adjusting the amount of air extracted from the compressor 5. The throttle valve 16 utilizes an instrumented pneumatic component, such as a simple manual valve. (In addition, an orifice may be provided in the air introduction pipe 15 instead of the throttle valve 16,
In that case as well, an instrumentation air component may be used as the orifice. ) Furthermore, openings or escape ports 17 are provided on both sides of the bearing casing 3 to allow air introduced into the room to escape.

In order to drive the turbine 4, high-temperature, high-pressure combustion exhaust gas 18 is supplied from an engine or the like, and the turbine 4 is driven to rotate. The rotation of the turbine 4 is transmitted to the compressor 5 via the shaft 6, and the air 19 introduced into the compressor 5 is
Compressed, high-pressure discharge air 20 is discharged from the discharge port and supplied to the engine and the like. Shaft 6
is supported by a high-pressure air film or layer formed between the shaft 6 and the bearings 8 and 9 due to its rotation.

By the way, when the engine load increases, the combustion exhaust gas 18 introduced from the engine into the turbine 4
pressure increases. However, since the space between the turbine casing 1 and the bearing casing 3 is sealed by a simple non-contact type labyrinth packing 12, the combustion exhaust gas 18 passes through the labyrinth packing 12 into the bearing casing 3. It leaks into.

However, in the case of the present invention, compressor 5
By introducing a portion of the discharged air 20 from the bearing housing 3 into the bearing housing 3, the exhaust gas 18 is prevented from leaking into the bearing housing 3. That is, a part of the discharged air 20 discharged from the compressor 5 is taken out from the intake port 13, passes through the air introduction pipe 15, and is introduced from the introduction port 14 into the thrust bearing 8 portion of the bearing casing 3. The air introduced into the thrust bearing 8 section passes through the gap between the thrust bearing 8 and the thrust collar 7, further passes through the journal bearing 9 section, and then enters the bearing through the relief ports 17, 17 provided on both sides of the bearing chamber 3. The air is exhausted to the outside of the vehicle compartment 3.

In this way, since a part of the air 20 discharged from the compressor 5 is introduced into the bearing casing 3, the indoor pressure of the bearing casing 3 increases, causing labyrinth packing 1.
2 can be prevented from leaking in. Furthermore, even if a small amount of exhaust gas 18 leaks into the bearing casing 3, this exhaust gas 18 will be absorbed into the air outlet 17 along with the air introduced into the bearing casing 3.
Air is scavenged from the Therefore, the exhaust gas 1 is deposited on the bearing surfaces of the thrust bearing 8 and the journal bearing 9 in the bearing chamber 3.
There is no worry that carbon or sludge in 8 will adhere. Therefore, there is no risk of accelerated wear on the bearing surface due to adhesion of carbon, etc. to the bearing surface.
The lifespan or durability of the thrust bearing and the journal bearing 9 can be maintained and their reliability can be improved.

Furthermore, by introducing air into the bearings 8 and 9, the bearings 8 and 9 can be cooled and kept clean. In addition, a throttle valve is provided in the air introduction pipe 15, and the discharge air 20 extracted from the compressor 5 is
Since the amount is adjusted to the minimum required for sealing the bearings 8 and 9, the performance of the compressor 5 will not be degraded.

In addition, although the above embodiment was a supercharger without a wastegate valve, the present invention can also be applied to a supercharger with a wastegate valve. Examples of this case are shown in FIGS. 3 and 4. In the illustrated example, the air introduction pipe 15 is branched from a T-piece 23 provided in a take-out pipe 22 for the discharged air to the wastegate actuator 21 . In this way, a part of the wastegate air line can be used also, and the equipment of the present invention can be simplified. In addition, the above T
Connect piece 23 to wastegate actuator 21
In addition, the mounting positions of the inlet 14 and the escape port 17 are determined by the bearing structure inside the bearing casing 3, and are not limited to the above embodiments. It is of course possible to change the position to another suitable position as long as the bearing part is not exposed to exhaust gas.

In summary, according to the present invention, the following excellent effects can be achieved.

(1) Since a part of the pressure air discharged from the compressor is supplied to the gas bearing part of the bearing casing, the internal pressure of the bearing casing increases, and it passes from the turbine casing through the labyrinth packing to the bearing casing. Prevents exhaust gas from leaking. Also. Even if some leakage occurs, the pressure passes through the gas bearing in the center of the bearing casing and is discharged from the relief port at the end of the bearing casing. The air is scavenged. Therefore, carbon and sludge in the exhaust gas can be prevented from adhering to the gas bearing surface, and wear and deterioration of the gas bearing portion can be avoided.

(2) By introducing pressurized air from the compressor into the gas bearing, the bearing can be cooled and kept clean for a long time.

(3) From (1) and (2) above, the durability of the gas bearing can be maintained and its reliability can be improved.

[Brief explanation of the drawing]

Figure 1 is an outline drawing showing an embodiment of a turbocharger equipped with a sealing device according to the present invention, Figure 2 is a seal gas system diagram of the turbocharger, and Figure 3 is a turbocharger equipped with a wastegate valve. FIG. 4 is an external view showing an example of a charger equipped with the device of the present invention, and FIG. 4 is a seal gas system diagram of the supercharger. In the figure, 1 is a turbine casing, 2 is a compressor casing, 3 is a bearing casing, 4 is a turbine, 5 is a compressor, 6 is a shaft, 7 is a thrust collar, 8 is a thrust bearing, 9 is a journal bearing, and 12 is a Labyrinth packing, 15 is an air introduction pipe, 16 is a throttle valve, 17 is a relief port, 18 is a combustion exhaust gas, 20 is discharge air, 21 is a waste gate actuator, and 23 is a T-piece.

Claims (1)

[Scope of utility model registration request] A turbine and a compressor driven by the turbine to compress intake air and discharge and supply pressurized air are connected via a shaft, and the shaft is connected by a gas bearing section consisting of a thrust bearing in the center of the bearing casing and radial bearings on both sides thereof. In a supercharger that is supported by a shaft and has a labyrinth seal between the bearing casing, the turbine casing, and the compressor casing, a part of the pressurized air discharged from the compressor is used as sealing gas in the center of the bearing casing. An air introduction pipe having a throttle valve for supplying gas to the gas bearing is provided, and relief ports for pressurized air passing from the thrust bearing to the radial bearing are formed at both ends of the bearing chamber to supply the gas to the gas bearing. A sealing device for a gas bearing portion of a supercharger, characterized in that gas inside the bearing compartment is scavenged from a relief port by the pressurized air.