Power plants – Fluid motor means driven by waste heat or by exhaust energy... – With supercharging means for engine
Reexamination Certificate
2000-09-21
2001-12-04
Denion, Thomas (Department: 3748)
Power plants
Fluid motor means driven by waste heat or by exhaust energy...
With supercharging means for engine
C060S562000, C060S564000, C060S605100, C060S605200, C060S559000, C416S19800R, C415S011000
Reexamination Certificate
active
06324848
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a turbocharger for use in an internal combustion engine, and, more particularly, to a turbocharger including a multi-stage compressor.
BACKGROUND ART
An internal combustion engine may include one or more turbochargers for compressing a fluid which is supplied to one or more combustion chambers within corresponding combustion cylinders. Each turbocharger typically includes a turbine driven by exhaust gases of the engine and a compressor which is driven by the turbine. The compressor receives the fluid to be compressed and supplies the fluid to the combustion chambers. The fluid which is compressed by the compressor may be in the form of combustion air or a fuel and air mixture.
The operating behavior of a compressor within a turbocharger may be graphically illustrated by a “compressor map” associated with the turbocharger in which the pressure ratio (compression outlet pressure divided by the inlet pressure) is plotted on the vertical axes and the flow is plotted on the horizontal axes. In general, the operating behavior of a compressor wheel is limited on the left side of the compressor map by a “surge line” and on the right side of the compressor map by a “choke line”. The surge line basically represents “stalling” of the air flow at the compressor inlet. With too small a volume flow and too high a pressure ratio, the flow will separate from the suction side of the blades on the compressor wheel, with the result that the discharge process is interrupted. The air flow through the compressor is reversed until a stable pressure ratio by positive volumetric flow rate is established, the pressure builds up again and the cycle repeats. This flow instability continues at a substantially fixed frequency and the resulting behavior is known as “surging”. The choke line represents the maximum centrifugal compressor volumetric flow rate, which is limited for instance by the cross-section at the compressor inlet. When the flow rate at the compressor inlet on other location reaches sonic velocity, no further flow rate increase is possible and choking results. Both surge and choking of a compressor should be avoided.
U.S. Pat. No. 3,044,683 (Woollenweber) discloses a fluid passage extending from the high pressure side of the compressor to the inlet side of a turbine. A spring loaded valve is disposed within the fluid passage and opens upon a high pressure condition within the compressor. The spring loaded valve thus merely acts to bypass some of the high pressure gas on an over pressure condition to the turbine of the turbocharger.
U.S. Pat. No. 5,724,813 (Fenelon et al.) assigned to the assignee of the present invention, discloses a turbocharger having a single stage compressor. A portion of the compressed gas from the single stage compressor may be recirculated to the outlet side of the turbine using controllably actuated valves. The control scheme utilizes only a single stage compressor.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, a turbocharger system for an internal combustion engine is provided with at least one rotatable shaft and a multi-stage compressor. The multi-stage compressor includes a first compressor wheel carried by a corresponding shaft, an axially extending first inlet associated with the first compressor wheel, a radially extending first outlet associated with the first compressor wheel, a second compressor wheel carried by a corresponding shaft, an axially extending second inlet associated with the second compressor wheel, and a radially extending second outlet associated with the second compressor wheel. An interstage duct fluidly interconnects in series the first outlet associated with the first compressor wheel with the second inlet associated with the second compressor wheel. At least one bypass duct is provided, with each bypass duct fluidly interconnecting the first outlet with the first inlet; the first outlet with an ambient environment; and/or the second outlet with the first outlet. At least one valve is provided, each valve being positioned within a corresponding bypass duct. A controller is coupled with each valve and selectively actuates each valve.
In another aspect of the invention, an internal combustion engine is provided with an exhaust manifold, an intake manifold and a turbocharger. The turbocharger includes at least one rotatable shaft; a turbine having a turbine wheel carried by a corresponding shaft; and a multi-stage compressor. The multi-stage compressor includes a first compressor wheel carried by a corresponding shaft, an axially extending first inlet associated with the first compressor wheel, a radially extending first outlet associated with the first compressor wheel, a second compressor wheel carried by a corresponding shaft, an axially extending second inlet associated with the second compressor wheel, and a radially extending second outlet associated with the second compressor wheel. An interstage duct fluidly interconnects in series the first outlet associated with the first compressor wheel with the second inlet associated with the second compressor wheel. At least one bypass duct is provided, each bypass duct fluidly interconnecting the first outlet with the first inlet; the first outlet with an ambient environment; and/or the second outlet with the first outlet. At least one valve is provided, each valve being positioned within a corresponding bypass duct. A controller is coupled with each valve and selectively actuates each valve.
In yet another aspect of the invention, a method of operating a turbocharger in an internal combustion engine is provided with the steps of: providing an exhaust manifold; providing an intake manifold; providing a turbocharger including a turbine having a turbine wheel carried by a corresponding shaft; a multi-stage compressor including a first compressor wheel carried by a corresponding shaft, an axially extending first inlet associated with the first compressor wheel, a radially extending first outlet associated with the first compressor wheel, a second compressor wheel carried by a corresponding shaft, an axially extending second inlet associated with the second compressor wheel, and a radially extending second outlet associated with the second compressor wheel; and an interstage duct fluidly interconnecting in series the first outlet associated with the first compressor wheel with the second inlet associated with the second compressor wheel; fluidly interconnecting the first outlet with the first inlet; the first outlet with an ambient environment; and/or second outlet with the first outlet using at least one bypass duct; positioning at least one valve within each bypass duct; coupling each valve with a controller; and selectively actuating each valve using the controller.
REFERENCES:
patent: 2189106 (1940-02-01), Garve et al.
patent: 3044683 (1962-07-01), Woollenweber, Jr.
patent: 4122679 (1978-10-01), Charron
patent: 4807150 (1989-02-01), Hobbs
patent: 4930315 (1990-06-01), Kanesaka
patent: 5406796 (1995-04-01), Hiereth et al.
patent: 5526645 (1996-06-01), Kaiser
patent: 5605044 (1997-02-01), Zimmer et al.
patent: 5724813 (1998-03-01), Fenelon et al.
patent: 6109248 (2000-08-01), Nilsson
patent: 6112523 (2000-09-01), Kamo et al.
patent: 2 186 023-A (1987-08-01), None
patent: 2-119627-A (1990-05-01), None
Gladden John R.
Wu Min
Caterpillar Inc.
Denion Thomas
Taylor Todd T.
Trieu Thai-Ba
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