Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2002-03-05
2004-01-20
Denion, Thomas (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C415S158000, C092S136000
Reexamination Certificate
active
06679057
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of turbochargers and, more particularly, to a variable geometry turbocharger comprising a variable geometry turbine members and variable geometry compressor members, and a system for providing simultaneous control of the same.
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, rotary action of the turbine also causes the air compressor impeller to spin within a compressor housing of the turbocharger that is separate from the turbine housing. The spinning action 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 amount by which the intake air is boosted or pressurized can be controlled by regulating the amount of exhaust gas that is passed through the turbine housing by a wastegate. Alternatively, the amount by which the intake air is boosted or pressurized can be controlled by changing the geometry of a movable member in the turbine housing that operates to regulate the passage of exhaust gas to the turbine. This alternative method of boost air regulating can be provided by opening or closing a movable exhaust gas channel or passage to the turbine running through the turbine housing, and/or by adjusting the position of one or more movable vanes disposed within the turbine housing to vary the gas flow velocity of exhaust gas to the turbine.
The use of adjustable vanes within a turbine housing can be used as one way of reducing turbo lag, i.e., the lag time between the time that the vehicle is accelerated from idle and sufficient pressure is developed by the turbocharger compressor to effect an appreciable increase in engine power, by reducing the flow area within the turbine housing to provide the necessary power to quickly accelerate the turbine wheel.
As the volumetric flow rate of exhaust gas increases with increasing engine RPM, the vanes are adjusted to increase the flow area within the turbine housing to enable the exhaust gas to generate the appropriate power to compress the necessary quantity of inlet air.
Turbochargers constructed having such an adjustable member within the turbine housing are referred to in industry as variable geometry turbochargers (VGTs). The movable member within such VGTs, in the form of vanes, nozzles or the like, is positioned in the turbine housing between an exhaust gas inlet and the turbine. The movable member is activatable from outside of the turbine housing by a suitable actuating mechanism to increase or decrease the exhaust gas flow within the turbine housing to regulate the air intake boost pressure as called for by the current engine operating conditions, as explained above.
VGTs known in the art can be actuated by using a pneumatic activating means, i.e., by using compressed air or the like or by hydraulic activating means, i.e., by using a pressurized fluid such as oil or the like. An example hydraulically activated actuator comprises a combined piston and rack and pinion assembly. The piston in such actuator assembly is reciprocated within a cylinder by pressurized oil that is passed through a dedicated oil passage within the turbocharger. The oil is passed to the piston at a particular pressure using a valve. A rack and pinion assembly is used with the piston to convert reciprocating piston movement into rotary movement that ultimately actuates the movable member within the turbine, e.g., a VGT vane or nozzle.
Much as it is desirable to adjust the flow of exhaust gas to the turbine, it is also desirable to adjust the flow rate of boosted air from a turbocharger compressor to generate the appropriate power to compress the necessary quantity of inlet air depending on the amount of exhaust gas reaching the turbine. Accordingly, VGTs are also known to comprise a movable member within the compressor housing to control and/or regulate the amount of boosted air that is compressed by the compressor. As with VGTs, similar types of actuators can be used to control such movable members.
In an effort to optimize turbocharged engine operation, it is desirable that a VGT be configured to provide adjustable turbine and compressor characteristics, and to provide such desired characteristic of adjustability in a trouble-free manner.
SUMMARY OF THE INVENTION
The present invention comprises a VGT for internal combustion engines. The turbocharger comprises a center housing having a shaft positioned axially therethrough having a first and a second shaft end. A turbine housing is attached to one side of the center housing and has a turbine wheel disposed therein that is coupled to the first end of the shaft.
A first variable geometry member is disposed within the turbine housing for controlling the flow of exhaust gas to the turbine wheel. In an example embodiment, the first variable geometry member comprises a plurality of movable turbine vanes that are interposed between an exhaust gas inlet and the turbine wheel. A turbine unison ring is rotatably positioned adjacent the plurality of turbine vanes and is coupled to the vanes to effect rotation of the turbine vanes radially inwardly towards or outwardly away from the turbine wheel.
A compressor housing is attached to another side of the center housing opposite the turbine housing and has a compressor impeller disposed therein, the compressor impeller is coupled to the second end of the shaft. A second variable geometry member is disposed within the compressor housing to control the flow of air from the compressor impeller. In an example embodiment, the variable geometry member comprises a plurality of movable compressor vanes interposed between an air outlet and the compressor impeller. A compressor unison ring is rotatably positioned adjacent the plurality of compressor vanes and is coupled to the compressor vanes to effect rotation of the compressor vanes radially inwardly towards or outwardly away from the compressor impeller.
An actuator assembly is disposed within the turbocharger and is connected to the first and second variable geometry members to provide simultaneous actuation of the same. The actuator assembly is configured to provide desired first and second variable geometry member operation by use of balancing mechanical and electro-hydraulic forces.
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patent: 6401563 (2002-06-01), Franklin
Denion Thomas
Honeywell-International Inc.
Pangrite Brian
Starr Ephraim
Trieu Thai-Ba
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