Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-04-26
2001-11-13
Nguyen, Hoang (Department: 3768)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S605200, C415S148000
Reexamination Certificate
active
06314736
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Priority is claimed under 35 U.S.C. 119 with respect to German Patent Application 199 61 613.2-13 filed on Dec. 21, 1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an exhaust gas turbocharger for an internal combustion engine and specifically to the turbine portion having variably adjustable blades.
2. Description of Related Art
A generic exhaust gas turbine for a turbocharger is disclosed in DE 195 43 190 C2 which shows adjustable stop bodies in an annular nozzle arrangement to provide a variable adjustable blade arrangement. The stop bodies are utilized to increase the operating reliability of the exhaust gas turbine particularly in an engine braking mode of operation.
In addition, DE 198 38 928 C1 discloses in an exhaust gas turbocharger a turbine portion having a variably adjustable series of guide-blades. For each guide-blade, a sealing element is provided and located in a pressurized space. The sealing element design is in the form of sealing cups adapted to be sealingly pressed onto the free end of a blade so that the series gap formed at the end of the blade is completely sealed off. A disadvantage of this, however, is that a large number of sealing elements is required, one for each blade, and this increases expense and the susceptibility to operating faults. Furthermore, during adjustment of the blade and sealing member high adjusting forces have to be exerted to overcome frictional forces generated by pressing the sealing element onto the blade. Moreover, there is the risk of damage caused by a complete elimination of the end gap which allows an undesirably high rotational speed of the turbocharger particularly in an engine braking mode from relatively high engine speeds. Another problem with this seal design may occur by an undesirably great thermal expansion of an associated blade.
Another device is shown in JP 001 130002 AA which discloses an adjustable series of blades in which a precisely defined sealing gap is set by means of a spacer member.
SUMMARY OF THE INVENTION
The present invention utilizes a variably adjustable exhaust gas turbine whose efficiency is achieved by blade adjustment as a function of the operating state of the internal combustion engine. In particular, the subject device provides an improvement in acceleration behavior of the turbine particularly during an engine-braking mode of operation and in driving modes, even at low engine rotational speeds. It provides a rapid build-up of the engine inlet pressure developed by the turbocharger and therefore a corresponding rapid build-up of braking or driving torque. Accordingly, any overload of the exhaust gas turbine or of entire exhaust gas turbocharger under extreme conditions is avoided.
This object is achieved, according to the invention, by means of apparatus and by a regulating process as described hereinafter. Specifically, the exhaust gas turbocharger can always be optimally adapted or set-up relative to a desirable operating state of the internal combustion engine by controlling the axial gap between a maximum allowable gap and substantially a zero gap. Thus, for example, after a an initial adjustment of the series of blades, the axial end gaps can be advantageously reduced between the maximum to near zero by a clamping action. Resultantly, acceleration is improved even at a low engine rotational speed and following an engine-braking mode of operation. At the same time, by reducing end gap losses, a more rapid build-up of the inlet charge pressure to the engine and consequently a rapid build-up of braking torque can be achieved.
In an advantageous refinement of the invention, the guide blades can be clamped, for example by an annular piston, between a part of the casing wall which surrounds or forms the angular nozzle. This clamping inhibits excitations of the guide blades in the series of guide-blades.
Conversely, by increasing the axial gap in a controlled manner between zero and a maximum, the efficiency of the turbine portion can be readily controlled.
A particular advantageous feature of the gap varying or setting control of the gas turbocharger according to the invention is that the exhaust gas turbine can be operated close to its desired rotative speed so that the exhaust gas turbine has a correspondingly high efficiency. By a controlled increase in the axial gap between the blades and the housing, the effectiveness and speed of the turbocharger can be decreased particularly in an upper range of engine speeds. This inhibits damage to the exhaust gas turbine or to the exhaust gas turbocharger by the corresponding lowering of efficiency.
REFERENCES:
patent: 5146752 (1992-09-01), Bruestle
patent: 5214920 (1993-06-01), Leavesley
patent: 5600956 (1997-02-01), Nytomt
patent: 5758500 (1998-06-01), Sumser et al.
patent: 5855117 (1999-01-01), Sumser et al.
patent: 195 43 190 C2 (1995-11-01), None
patent: 198 38 928 C1 (1998-08-01), None
patent: 0010130002 AA (1987-11-01), None
Article by A. Feuerstein and W. Bialojan entitled “Beschichten im Vakuum” dated Dec. 1992.
Daudel Helmut
Erdmann Wolfgang
Fledersbacher Peter
Funke Carsten
Löffler Paul
Bach Klaus J.
Daimler-Chrysler AG
Nguyen Hoang
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