Rotary kinetic fluid motors or pumps – Selectively adjustable vane or working fluid control means – Upstream of runner
Reexamination Certificate
2001-01-24
2003-04-08
Denion, Thomas (Department: 3748)
Rotary kinetic fluid motors or pumps
Selectively adjustable vane or working fluid control means
Upstream of runner
C415S150000, C415S164000
Reexamination Certificate
active
06543994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a variable-capacity turbocharger. More specifically, it concerns an improvement of a nozzle unit for supplying exhaust gases to a turbine of the turbocharger.
2. Description of the Related Art
A turbocharger is an effective means to increase the output of an internal combustion engine. A turbine is rotated by the exhaust gas from the engine, and a compressor mounted on the same shaft as the turbine pressurizes the air supplied to the engine. Turbochargers are currently installed in a variety of engines. However, the flow rate of the exhaust gas varies with the speed of the engine's revolution. The flow rate of the exhaust gas which is actually supplied from the engine will not always be that needed to produce the ideal operating conditions for the supercharger. To rectify this situation and allow the turbocharger's capacity to be used to its best advantage, a variable-capacity turbocharger has been developed. In a variable-capacity turbocharger, the flow of the exhaust gas in the turbine compartment is regulated according to the operating state of the internal combustion engine.
This sort of variable-capacity turbocharger has a number of nozzle vanes on the nozzle unit of the turbine, which is inside a housing.
FIG. 8
shows a partial cross section of the nozzle unit in a variable-capacity turbocharger belonging to the prior art.
In
FIG. 8
, turbine
228
is supported by bearings in a main housing of the variable-capacity turbocharger in such a way that it is free to rotate. The exhaust gas from the internal combustion engine flows into housing
220
through an intake port of the variable-capacity turbocharger. It is supplied to turbine
228
by way of scroll channel
226
which is formed in housing
220
and nozzle unit
210
which forms the inlet to the turbine
228
. The exhaust gas supplied to turbine
228
is then exhausted through the exhaust port after it has driven the turbine
228
.
Nozzle unit
210
comprises mounting plate
202
, which is fixed to housing
220
, and side plate
206
, which is placed opposite mounting plate
202
. A number of nozzle vanes
204
are placed at equal intervals along the circumference between the two plates. Side plate
206
is fixed to mounting plate
202
by supporting bolt
208
, which goes through the plate
206
. Nozzle vanes
204
have a shaft portion. They are mounted on mounting plate
202
in such a way that they are free to rotate with the shaft portion.
Because side plate
206
is fixed in place by support bolt
208
, the heat of the exhaust gas which is supplied to the turbine raises its temperature, causing it to thermally deform. A space is provided between nozzle vanes
204
and side plate
206
, as in
FIG. 8
, in order to prevent nozzle vanes
204
from catching or sticking during rotation and allow them to operate smoothly. This is why in variable-capacity turbochargers of the prior art a portion of the exhaust gas being supplied to scroll channel
226
is routed through the space between nozzle vanes
204
and side plate
206
and supplied to turbine
228
without going through the area around nozzle vanes
204
. In the prior art design, then, because some of the gas is supplied to turbine
228
without passing through the channel around vanes
204
, the efficiency of the variable-capacity turbocharger decreases.
SUMMARY OF THE INVENTION
This invention is to solve the shortcomings of the prior art design described above. The object of this invention is to minimize as much as possible or eliminate the quantity of exhaust gas supplied to the turbine without going through the channels between the nozzle vanes. This invention is also effective at minimizing the quantity of exhaust gas supplied to the turbine from behind the side plate without going through the nozzle unit.
A variable-capacity turbocharger which controls the opening degree of nozzle vanes has a turbine provided in a housing, which is free to rotate on a turbine shaft, a plurality of nozzle vanes arranged in nozzle units around the turbine in the housing, a link plate which rotates freely around the turbine provided in the housing, which is connected to the nozzle vanes by means of a plurality of levers, and which continuously moves the nozzle vanes synchronously between the open and closed positions, and an actuator outside the housing, which is connected to the link plate through a transmission mechanism. The turbocharger according to this invention is distinguished by the following features. It has a mounting plate fixed to the housing, and a side plate installed in a recess provided in the housing in such a way that the side plate can move in the recess, both of which are provided parallel to the turbine shaft. A pushing means pushes the side plate toward the mounting plate and a limiting means limits the movement of the side plate parallel to the turbine shaft toward the mounting plate.
The pushing means to push the side plate can be a pressure chamber created between the side plate and the recess, or a spring plate mounted between the side plate and the recess.
The side plate has a doughnut shape whose center is the turbine shaft. The recess has a diameter slightly greater than the diameter of the side plate, and the recess also has, on the inner surface, a round projection which protrudes parallel to the turbine shaft toward the side plate. The spring plate is engaged with and fixed to the round projection.
REFERENCES:
patent: 4643640 (1987-02-01), Burdette et al.
patent: 5146752 (1992-09-01), Bruestle
patent: 5851104 (1998-12-01), Dakin et al.
patent: 6312217 (2001-11-01), Takahashi
patent: 409296731 (1997-11-01), None
patent: 410331649 (1998-12-01), None
patent: 11062603 (1999-03-01), None
patent: 02000008870 (2000-01-01), None
patent: 2001073787 (2001-03-01), None
patent: 02001329851 (2001-11-01), None
Denion Thomas
Mitsubishi Heavy Industries Ltd.
Trieu Thai Ba
Wenderoth , Lind & Ponack, L.L.P.
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