Spring-loaded vaned diffuser

Details Spring-loaded vaned diffuser Spring-loaded vaned diffuser

1999-09-23

2001-01-02

Lopez, F. Daniel (Department: 3745)

Rotary kinetic fluid motors or pumps

Including working fluid force responsive vane or flow control

C415S148000, C415S211200

Utility Patent

active

06168375

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to the field of turbochargers and, more particularly, to a spring-loaded vane diffuser that is positioned within a compressor housing of an exhaust-gas turbocharger.
BACKGROUND OF THE INVENTION
Turbochargers for gasoline and diesel internal combustion engines are known devices used in the art for pressurizing or boosting the intake air stream, routed to a combustion chamber of the engine, by using the heat and volumetric flow of exhaust gas exiting the engine. Specifically, the exhaust gas exiting the engine is routed into a turbine housing of a turbocharger in a manner that causes an exhaust gas-driven turbine to spin within the housing. The exhaust gas-driven turbine is mounted onto one end of a shaft that is common to a radial air compressor impeller mounted onto an opposite end of the shaft. Thus, rotation of the turbine also causes the air compressor impeller to spin within a compressor housing of the turbocharger that is separate from the exhaust housing. The spinning of the air compressor impeller causes intake air to enter the compressor housing and be pressurized or boosted a desired amount before it is mixed with fuel and combusted within the engine combustion chamber.
The compressor housing includes a diffuser that can either be part of the compressor housing or be a separate component attached within the compressor housing. The diffuser acts like a nozzle in reverse within the compressor housing to slow down the air passing therethrough without creating turbulence. The process of slowing down the air flow within the compressor housing converts velocity energy to pressure energy and produced air boost pressure in the turbocharger. The diffuser can include one or more vanes that project outwardly from a diffuser surface and that extend in a generally radial direction in line with the direction of air flow from the compressor impeller. Vanes are used with the diffuser to force the air leaving the compressor impeller to flow in a particular direction, reducing air flow velocity in a way that favors a particular application demand, e.g., a particular engine speed or torque requirement.
Vane diffusers known in the art include those constructed as a separate component of the compressor housing, and that are shaped in the form of an annular ring designed to fit against a backplate axial wall surface. At least one pin is placed axially between the vane diffuser and the backplate to prevent the vane diffuser from rotating within the compressor housing. An elastomeric O-ring energizer is interposed between the vane diffuser and the backplate to both provide an air leakage seal and to pressure load the vane diffuser away from the backplate. Such pressure loading is desired to urge the vane diffuser away from the backplate because the compressor housing is known to move axially away from the backplate under turbocharger operating temperatures and pressures. Thus, such pressure loading is intended to keep the vane diffuser in contact with the housing during such axial movement to prevent compressor performance losses due to air flow restrictions between the compressor housing and vane diffuser. A concern with the vane diffuser described above is that the O-ring energizer is unable to provide both the range and consistent degree of pressure loading that is desired. This is so because: (1) the spring force provided by the O-ring energizer decreases rapidly as the vane diffuser is moved away from the backplate (due to the effect of static pressure within the compressor and its migration between the vane diffuser and backplate), thus is effective for only a very limited range of motion; and (2) the available elastomers used for the O-ring energizer are known to degrade and creep at the high compressor operating temperatures, causing the energizer spring rate to decrease over time.
It is, therefore, desirable that a vane diffuser for use within a compressor housing be constructed to provide constant pressure loading during compressor operating temperatures and pressures to ensure that the vane diffuser remains in contact with the compressor housing as the compressor housing moves during compressor operation. It is desired that such vane diffuser also be constructed to reduce or prevent undesirable aerodynamic effects within the compressor housing during the above-mentioned compressor housing movement. It is also desired that such vane diffuser be constructed in such manner to prevent undesired binding effects during compressor operation that could interfere with a desired degree of axial movement to track the compressor housing.


REFERENCES:
patent: 2881972 (1959-04-01), Feilden
patent: 3010697 (1961-11-01), Lazo et al.
patent: 3975911 (1976-08-01), Morgulis et al.
patent: 4770605 (1988-09-01), Nakatomi
patent: 4844690 (1989-07-01), DeLaurier et al.
patent: 4932207 (1990-06-01), Harris et al.
patent: 5125228 (1992-06-01), Jewess et al.

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