Rotary kinetic fluid motors or pumps – Selectively adjustable vane or working fluid control means – Upstream of runner
Reexamination Certificate
2001-05-14
2004-03-02
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
Selectively adjustable vane or working fluid control means
Upstream of runner
C415S150000, C060S602000, C029S889220
Reexamination Certificate
active
06699010
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a nozzle adjustment mechanism for a radial-flow variable-capacity turbine which may be used as a supercharger (an exhaust turbocharger) for an internal combustion engine. This type of radial-flow variable-capacity turbine is so constructed that the operating gases pass through a number of variably angled nozzle vanes from a coil-shaped scroll in the turbine casing, and the gases are made to flow to the turbine rotor so that they drive the rotation of the rotor.
2. Description of the Related Art
In recent years, if an internal combustion engine has a supercharger, it has become more and more common for it to be the kind of supercharger with a variable-capacity turbine. Such a turbine varies the flow rate of the exhaust gases transported from a coil-shaped scroll to the turbine rotor according to the operating state of the engine, and it does this variation in such a way as to match the flow rate of the engine exhaust gases to that rate which would produce the optimal operating condition of the supercharger.
The basic structure of a conventional supercharger is shown in FIG.
7
and FIG.
8
.
FIG. 7
is a perspective drawing of a supercharger with a variable-capacity turbine belonging to the prior art, and
FIG. 8
shows an example of how link plate
3
, nozzle vanes
2
, and lever
1
are connected in the previous art. In
FIG. 7
,
10
is the turbine casing and
11
is the coil-shaped scroll in the outer periphery of the turbine casing
10
. Number
12
is the turbine rotor, which is supported on the center of the casing by bearings (not pictured) such that it is free to rotate. The rotor is coaxial with the compressor (also not pictured).
Number
2
is a nozzle vane, a number of which are arranged in spaces along the circumference of the turbine on the inner periphery of the scroll
11
. Nozzle shafts
02
, on the inner extremity of the nozzle vanes
2
, are supported in nozzle mounts
4
, which are fixed to the turbine casing
10
, such that they are free to rotate so that the angle of the nozzle vanes varies.
14
is the gas exhaust casing which guides the exhaust gases out of the engine once the gases have completed the work of expanding to drive the turbine rotor
12
. The gas exhaust casing is fixed to the turbine casing
10
.
Number
3
is a disk-shaped link plate. It is supported by the turbine casing
10
in such a way that it is free to rotate. Indentations
3
a
are provided along the periphery in which levers
1
, which will be discussed shortly, can engage. Number
07
is an actuator which drives nozzle vanes
2
through the link plate
3
. Number
005
is a lever which connects an actuator rod
7
of the actuator
07
to the link plate
3
.
FIG. 8
shows how the link plate
3
, levers
1
, and nozzle vanes
2
are assembled. The indentations (oblong holes)
3
a
are provided on the inner periphery of the disk-shaped link plate
3
, at regular intervals along the circumference of the turbine. Bosses
6
, formed on the outer extremities of levers
1
, engage in the indentations (oblong holes)
3
a
in such a way that they can rotate and scrape the surface of the indentation. The nozzle shaft
02
of each nozzle vane
2
is fixed to the inner extremity of one of the levers
1
.
In this sort of variable-capacity turbine, the reciprocating displacement of the actuator
07
is transmitted to the link plate
3
by way of actuator rod
7
and lever
005
of the crank mechanism, thus driving the rotation of the link plate
3
. When the link plate
3
rotates, the bosses
6
of the levers
1
, which are engaged in indentations
3
a
of the link plate
3
, move along the circumference of the link plate. Nozzle shafts
02
, which are fixed to the interior extremities of the levers
1
, thus rotate. This causes nozzle vanes
2
to rotate, changing the angle of their vanes.
In the variable-capacity turbine pictured in
FIGS. 7 and 8
, bosses
6
on the outer extremities of levers
1
engage in indentations
3
a
, which are provided on the inside of disk-shaped link plate
3
at regular intervals along the circumference of the turbine. The nozzle shafts
02
of nozzle vanes
2
are fixed to the interior extremities of the levers
1
. Most variable-capacity turbines described above are used as exhaust gas turbines in the superchargers of automotive internal combustion engines. Such superchargers are small, so nozzle shaft
02
and the connecting hole of the nozzle vane
2
must have a small diameter, and with respect to strength, they will never be able to sustain much force. In general, therefore, the connection between nozzle vane
2
and lever
1
is made by pressing in order to secure the strength. In the prior art design shown in
FIGS. 7 and 8
, the edge of nozzle shaft
02
is pushed into the connecting hole in lever plate
1
, and the connecting hole grips the edge of nozzle shaft
02
. The end of the nozzle shaft is then riveted or welded so that nozzle vane
2
and lever
1
cannot rotate with respect to each other, but will remain fixed. Thus nozzle vane
2
and lever
1
are joined to each other.
In other words, in the technique employed in the prior art, when the connecting hole is made to grip the edge of nozzle shaft
02
, both the connecting hole and the edge are forced to undergo deformation. Thus in order to fasten together nozzle shaft
02
of nozzle vane
2
and lever
1
, a great deal of force is needed to push the shaft into the connecting hole. When this prior-art technique is used, then, as has been discussed, a small-diameter shaft
02
is forced into a small-diameter connecting hole with great force to join the two together. As a result, there is a chance that the nozzle shaft
02
might break or that some of connecting holes might break off when a large rotary force is applied to the area where the edge of the nozzle shaft
02
and connecting hole are connected, or that the portion where these two members are connected could be damaged.
Furthermore, since nozzle vane
2
, being exposed to the exhaust gases, attains quite a high temperature, the portion where the edge of the nozzle shaft
02
goes into connecting hole, where the nozzle vane
2
and lever
1
are joined, also attains a high temperature. As was explained earlier, the connection is achieved by deformation, so its strength at high temperatures will be diminished. This will make the nozzle shaft
02
of nozzle vane
2
more prone to the type of damage mentioned above.
The vane angle of the variable-capacity turbine must necessarily be controlled closely. In the prior art described above, the relative angle of the nozzle vane
2
with respect to lever
1
is set during assembly with the help of a jig. This required a large number of assembly processes as well as special assembly tools such as the jig, driving up the production cost.
SUMMARY OF THE INVENTION
In view of these problems in the prior art, the objective of this invention is to provide a nozzle adjustment mechanism for a variable-capacity turbine which would have the following features. The connecting lever to connect the nozzle drive component driven by the actuator to the nozzle vane, and the edge of the nozzle shaft on the nozzle vane, would have a high degree of strength and would not experience deformation. There would be no need for special assembly tools such as a jig, and a highly accurate connection would be achieved with fewer assembly processes and at a lower cost.
The first preferred embodiment of this invention comprises a variable-capacity turbine which has a coil-shaped scroll in the turbine casing. A number of nozzle vanes are arranged along the circumference of the turbine at the inner peripheral side of the scroll and are supported on the turbine casing in such a way that they can rotate to vary the angle of the vanes. A turbine rotor rotates freely on the inner periphery of the nozzle vanes. Operating gases are made to flow from the scroll through the nozzle vanes to the turbine rotor, driving the rotation of the rotor. The turbine has
Mitsubishi Heavy Industries Ltd.
Verdier Christopher
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