Turbocharger

Details Turbocharger Turbocharger

2000-06-19

2001-11-20

Denion, Thomas (Department: 3748)

Power plants

Fluid motor means driven by waste heat or by exhaust energy...

With supercharging means for engine

72, 72

Reexamination Certificate

active

06318086

ABSTRACT:

FIELD OF THE INVENTION
The invention deals with a turbocharger according to the preamble of claim
1
.
BACKGROUND OF THE INVENTION
An RR turbocharger, for example, has been disclosed by the Brown Boveri reprint Mitteilungen No. 4/5, 1971. For better understanding, this turbocharger is reproduced in FIG.
1
. The turbocharger is composed of a radial compressor having a bladed or unbladed diffuser and of a radial turbine. The rotor of the turbocharger consists of a shaft, on which the turbine wheel is mounted at one end and the compressor wheel is mounted at the other end. In the center part of the housing of the turbocharger, the shaft is mounted on pressure-lubricated plain bearings. The housing, for example, may be uncooled or water-cooled. In order to prevent the exhaust gases from penetrating into the bearing space, sealing air is directed to the turbine hub from the compressor side. The path of the sealing air extracted from the compressor is indicated by white arrows in FIG.
1
. In addition, this arrangement achieves a reduced heat flow from the turbine wheel through the shaft to the rotor bearing. Due to being supplied with sealing air, the turbine-side bearing arrangement is not subjected to any higher temperatures than the compressor-side bearing arrangement. The temperature level therefore poses no problem even after the engine has been shut down, so that no undesirable coking of the lubricating oil occurs. In order not to obtain any positive pressure in the bearing space, the spaces on both sides of the bearing space are connected to the atmosphere by passages. The bearing housing is effectively protected against the high temperature of the turbine space by an intermediate wall which is cooled by the sealing air. However, this type of sealing-air supply has an adverse effect in particular when a gas is mixed with the compressor air, which may occur, for example, during the compression of biogas. This may then lead to explosive compositions of the sealing air, which ignite in the hot surroundings of the turbine hub. Direct extraction of the sealing air from the compressor is therefore made impossible. The sealing air enriched with the gas should also not pass into the environment. This is problematical, since external air is often not present in the requisite quantity, and separate compressors constitute a considerable price disadvantage. This applies in particular in the case of turbochargers of variable geometry, (VTG), since these turbochargers have an increased sealing-air requirement.
SUMMARY OF THE INVENTION
One objective of the present invention is to overcome these disadvantages. The invention achieves the object of providing a turbocharger with which it is possible to enrich the compressor air with a gas without having to fear an explosion risk in the case of the sealing air due to an increased temperature of the turbine wheel of the turbocharger. In addition, for reasons of environmental protection, a situation in which the sealing air enriched with the gas mixture is discharged to the surroundings is to be avoided.
According to the invention, this object is achieved in a turbocharger including a small turbocharger which contains a shaft, a compressor fastened to the shaft and having a feed line and a discharge line, and a turbine wheel fastened to the shaft and having a feed line and a discharge line is arranged in such a way that the discharge line of the compressor of the small turbocharger is connected for the sealing-air supply for the turbine wheel of the turbocharger.
A gas may be advantageously mixed with the air of the turbocharger, since the sealing-air supply is effected by the compressor of the small turbocharger. In an exemplary embodiment, the turbocharger is a turbocharger of variable geometry, since this turbocharger is distinguished by increased sealing-air consumption. With the proposed configuration, the sealing-air pressure of the turbocharger is advantageously automatically adapted to the turbine inlet pressure. Furthermore, it is advantageously possible to connect the feed and discharge lines of the small turbine wheel to the feed and discharge lines of the turbine wheel via a common control a pressure reducing element such as a restrictor for example.


REFERENCES:
patent: 4422296 (1983-12-01), Dinger et al.
patent: 5063744 (1991-11-01), Ishiyama et al.
patent: 5611202 (1997-03-01), Sumser et al.
patent: 4215301A1 (1993-11-01), None
patent: 4225625A1 (1994-02-01), None
patent: 3704967C1 (1988-05-01), None
“Die neue Baureihe der RR-Turbolader”, Perego, et al., Brown Boveri Mitteilungen, Nr. 4/5, 1971, pp. 3-7.

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