U.S. patent application number 09/767735 was filed with the patent office on 2001-08-16 for variable-capacity turbine.
Invention is credited to Jinnai, Yasuaki.
Application Number | 20010013339 09/767735 |
Document ID | / |
Family ID | 18541163 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013339 |
Kind Code |
A1 |
Jinnai, Yasuaki |
August 16, 2001 |
Variable-capacity turbine
Abstract
The object of this invention is to provide a nozzle drive
mechanism for the link plate 112, which can operate all the nozzle
vanes smoothly and synchronously. The nozzle vanes 104 are
supported in such a way that the nozzle vanes are free to rotate
between the open and closed positions on nozzle shafts, and the
nozzle vanes connected to levers 114 which correspond to the nozzle
shafts so as to rotate along with the levers 114. Each boss 114a at
the end of each lever 114 functions as a shaft which are parallel
to the nozzle shaft. The shafts 114a in the nozzle vanes engage in
oblong holes 114a in the link plate 112 in such a way that they are
free to swing, and are thereby connected to the link plate. The
declined straight or curved centerline which runs the oblong hole
to the oblong direction, extends at a given angle with respect to
the radius of the link plate.
Inventors: |
Jinnai, Yasuaki;
(Kanagawa-ken, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18541163 |
Appl. No.: |
09/767735 |
Filed: |
January 24, 2001 |
Current U.S.
Class: |
123/561 |
Current CPC
Class: |
F02C 6/12 20130101; F01D
17/165 20130101; F05D 2250/71 20130101; F05D 2220/40 20130101 |
Class at
Publication: |
123/561 |
International
Class: |
F02B 033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2000 |
JP |
2000-013598 |
Claims
What is claimed is:
1. A variable-capacity turbocharger which controls the opening
degree of the nozzle vanes, comprising: 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 said turbine in said
housing, supported in such a way that said nozzle vanes are free to
rotate between the open and closed positions on nozzle shafts, and
said nozzle vanes connected to levers which correspond to said
nozzle shafts so as to rotate along with said levers, each boss at
the end of each lever provided with a shaft which are parallel to
said nozzle shaft; a link plate which rotates freely around said
turbine provided in said housing, which is connected to said nozzle
vanes by said levers and continuously moves said nozzle vanes
synchronously between the open and closed positions, and said boss
provided at the end of each lever engaged in an oblong hole
provided in said link plate in such a way that said boss is free to
swing in said oblong hole, and is thereby connected to said link
plate; and an actuator outside said housing, which is connected to
said link plate through a transmission mechanism; wherein a
declined straight or curved centerline which runs said oblong hole
to the oblong direction, extends at a given angle with respect to
the radius of said link plate.
2. A variable-capacity turbocharger according to claim 1, wherein
said curved center line which runs said oblong hole to the oblong
direction, is curved along an arc tangent to said declined straight
line extending at a given angle with respect to the radius of said
link plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention concerns a variable-capacity turbocharger
which can control the amount of exhaust gas provided into the
turbine compartment by operating the nozzle vanes. More
specifically, it concerns an improvement of the nozzle drive
mechanism to transmit to the nozzle vanes the displacement of the
actuator which operates the nozzle vanes.
[0003] 2. Description of the Related Art
[0004] 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, the 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.
[0005] This sort of variable turbocharger has a number of nozzle
vanes in the nozzle unit of the turbine, which is inside a housing.
The nozzle vanes provided on the nozzle shaft are supported in such
a way that they can rotate between the open and closed positions.
The nozzle shaft is connected through a lever to a link plate which
has a doughnut shape. The link plate rotates freely on the rotary
axis of the turbine. An actuator on the outside of the housing
causes the link plate to rotate by means of a transmission
mechanism. When the link plate rotates, the nozzle vanes operate
synchronously, continuously moving between the open and closed
positions to adjust the degree of opening of the nozzle vanes.
[0006] In the nozzle drive mechanism to drive the nozzle vanes
according to the prior art, the rotary action of the link plate is
not transmitted smoothly into the rotary action of the nozzle
vanes. To achieve the desired action of the link plate, the
actuator on the outside of the housing of the variable turbocharger
had to be large enough to produce an appropriate force.
SUMMARY OF THE INVENTION
[0007] The technical problem which this invention addressed is to
solve this shortcoming in the prior art. The object of this
invention is to provide a nozzle drive mechanism for the link
plate, which can operate all the nozzle vanes smoothly and
synchronously.
[0008] The variable-capacity turbocharger which controls the
opening degree of the nozzle vanes according to this invention 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 the levers and 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.
[0009] The invention disclosed in the first preferred embodiment of
this invention is a variable turbocharger which is distinguished by
the following.
[0010] The nozzle vanes are supported in such a way that the nozzle
vanes are free to rotate between the open and closed positions on
nozzle shafts, and the nozzle vanes connected to levers which
correspond to the nozzle shafts so as to rotate along with the
levers, each boss at the end of each lever provided with a shaft
which are parallel to the nozzle shaft. The shafts in the nozzle
vanes engage in oblong holes in the link plate in such a way that
they are free to swing, and are thereby connected to the link
plate. The declined straight or curved centerline which runs the
oblong hole to the oblong direction, extends at a given angle with
respect to the radius of the link plate.
[0011] With the invention disclosed above, the oblong holes in the
link plate which receive the shafts of the levers extend in the
axial direction at a given angle with respect to the radius of the
link plate as defined by its rotational center. Thus when the link
plate rotates, there is a component in the generated force which
acts on the link plate at the point of contact of the shaft with
the hole which pushes the shaft in the radial direction. The shafts
of the levers can move smoothly in the radial direction within the
holes in the link plate, and the link plate can operate easily.
[0012] The invention disclosed in the second preferred embodiment
of this invention has curved oblong hole. The curved centerline
which runs the oblong hole to the oblong direction, is curved along
an arc tangent to the declined straight line extending at a given
angle with respect to the radius of the link plate.
[0013] With the invention disclosed above, each of the oblong holes
in the link plate which receive the shafts of the levers is curved
along an arc tangent to a line extending at a given angle with
respect to one of the radii from the rotational center of the link
plate. When the link plate rotates, the component of the pushing
force on the shaft which acts in the radial direction is greater
than in the invention disclosed in claim 1 of this application.
This allows the shafts of the levers to move more smoothly in the
radial direction within the holes in the link plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a lateral view of the exterior of a
variable-capacity turbocharger in which this invention is
implemented.
[0015] FIG. 2 is a cross section of the turbine compartment in the
first preferred embodiment.
[0016] FIG. 3 is a partially cut away frontal view of the
variable-capacity turbocharger in FIG. 1.
[0017] FIG. 4 is an enlargement of a portion of FIG. 3. It shows
the transmission mechanism which transmits the action of the
actuator to the link plate and the elements which link the two.
[0018] FIG. 5 is a plan view of the link plate shown in FIG. 4.
[0019] FIG. 6 is an enlarged view of the oblong hole on the link
plate according to a preferred embodiment of this invention.
[0020] FIG. 7 is a partial plain view of the link plate according
to another preferred embodiment of this invention.
[0021] FIG. 8 is an exploded view of the transmission mechanism to
transmit to the link plate.
[0022] In these drawings, 10 is turbine casing, 50 is actuator, 52
is rod, 54 is link member, 104 is nozzle vane, 112 is link plate,
112d is oblong hole on the link plate, 112d" is oblong hole
according to another preferred embodiment, 114 is lever, 120 is
swinging member, 130 is bridge, 140 is roller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] In-this section we shall explain several preferred
embodiments of this invention with reference to the appended
drawings. Whenever the shapes, relative positions and other aspects
of the parts described in the embodiments are not clearly defined,
the scope of the invention is not limited only to the parts shown,
which are meant merely for the purpose of illustration.
[0024] In this section we shall explain two preferred embodiments
of the invention with reference to the appended drawings.
[0025] FIG. 1 illustrates the external appearance of a
variable-capacity turbocharger 10 in which this invention has been
implemented. Variable-capacity turbocharger 10 includes a housing,
which comprises turbine housing 20, compressor housing 40 and main
housing 30, which is between turbine housing 20 and compressor
housing 40. Turbine housing 20 has an intake port 22 and an exhaust
port 24. Compressor housing 40 has an intake port 44 and a
discharge port 42.
[0026] On the outside of the housings 20, 30 and 40 is actuator 50,
which drives the nozzle vanes (to be explained shortly). Actuator
50 uses air pressure, or more specifically it uses the negative
pressure of the air sucked into the internal combustion engine (not
pictured) on which the variable-capacity turbocharger 10 is
installed, to cause rod 52 to move forward and back. It is,
however, possible in this invention to replace the actuator by any
type of actuator which functions the same, such as an active
pressure actuator, or a magnetic actuator.
[0027] The turbine compartment, especially main housing, is shown
in FIG. 2. As can be seen in FIG. 2, turbine shaft 32 is supported
in main housing 30 in such a way that it is free to rotate. Turbine
28, which is mounted to one end of turbine shaft 32, is inside
turbine housing 20. The exhaust gas from the internal combustion
engine is conducted from intake port 22 into turbine housing 20. It
is supplied to turbine 28 through scroll channel 26, which is
created on the inside of turbine housing 20, and nozzle unit 100,
which is the inlet to turbine 28. After it drives the turbine 28,
the exhaust gas which was supplied is exhausted through exhaust
port 24.
[0028] Nozzle unit 100 comprises mounting plate 102, which is fixed
to turbine housing 20, and side plate 106, which faces mounting
plate 102 and is mounted in the axial direction. A number of nozzle
vanes 104 are placed between the two plates at regular intervals
along the circumference of the shaft. At the base of nozzle vanes
104 is shaft portion 104a, which is mounted to mounting plate 102
so that portion 104a is free to rotate the vanes between the open
and closed positions. The end 104b of each shaft portion 104a of
nozzle vane assembly 104 goes through mounting plate 102 in the
axial direction. The shafts are connected to the various levers 114
which correspond to the nozzle vanes. (See FIGS. 3 and 4). The
nozzle vane 104 rotates via nozzle shaft 104a according to the
rotation of lever 114. Each lever 114 has a hole 114b to receive
the end 104b of one of the shaft portions 104a, and a boss, shaft
portion 114a, on the side opposite the hole 114b.
[0029] The shaft 114a of lever 114 can slide within the oblong hole
112d provided at regular intervals along the circumference of link
plate 112. There is a cylindrical boss 102a on the side of mounting
plate 102 opposite nozzle unit 100. An annular link plate 112 (See
FIG. 5) is mounted to the boss 102a so that it is free to rotate on
the rotational axis of turbine 28. Link plate 112 has a series of
oblong holes 112d at regular intervals along its circumference to
receive the shaft portions 114a of levers 114. Further, link plate
112 has on the same surface a trapezoidal elongated portion 112a on
one side. The end of the elongated portion 112a is divided into two
portions to form locking arms 112c. The two arms 112c form a
rectangular recession 112b.
[0030] As is shown in FIGS. 5 and 6 by the broken line with two
dots, in the prior art, oblong hole 112d' of link plate 112 is
formed on a radius of the rotational center of link plate 112,
i.e., it is formed on a radius of a circle whose center is the
rotational center O (turbine shaft) of turbine 28 in the variable
turbocharger 10. As we have explained, with this sort of prior art
design, actuator 50 must be able to produce a great deal of force
because link plate 12 does not operate easily. To address this
problem, in this embodiment, the center line r which runs
lengthwise through oblong hole 112d of link plate 112 is inclined
at an angle with respect to a line R which runs the center of the
oblong hole 112d and the center O of turbine 28. This design
enables link plate 112 to rotate smoothly and reduces the load
imposed on actuator 50.
[0031] The variable-capacity turbocharger 10 of this embodiment
also has a transmission mechanism to transmit the action of the
actuator 50 to link plate 112. The transmission mechanism includes
rod 52 of actuator 50; link member 54 (see FIG. 1), which is
connected to the end of rod 52 by pin 50a; swinging member 120 (see
FIGS. 2 and 8), which is connected to the link member 54; and
roller 140 and bridge 130, which are between member 120 and link
plate 112, and which serve to connect the transmission mechanism to
link plate 112.
[0032] As can be seen in FIG. 8, swinging member 120 comprises arm
122; shaft 124, which extends along a given axis O from one end of
arm 122, and is supported by turbine housing 20 through sleeve 118
in such a way that it can freely rotate; connector 128, which is on
the end of shaft 124 and coaxial with it, and connected to link
member 54 in such a way that it cannot move relative to the link
member; and pin 126, which extends from the side of arm 122
opposite shaft 124 and is parallel to that shaft. Swinging member
120 may be made of a metallic material, for example, stainless
steel. Ideally, it should be formed of a single piece of austenitic
stainless steel. Swinging member 120, arm 122, shaft 124, connector
128 and pin 126 may be formed separately and welded together.
[0033] As shown in FIG. 7, bridge 130 comprises two flat plates
132, which are positioned parallel to each other with a slight gap
between them, and center unit 134, which connects the two plates
132. At the center unit 134 provided between the two plates 132 is
a groove 136 in which the locking arms 112c of link plate 112
engage. Part of bridge 130, including center unit 134, is removed
to the middle of the bridge to form cut-away portion 138. The two
opposed surfaces are parallel and slide against each other. As can
be seen in FIG. 8, when the transmission mechanism is assembled,
the locking unit is formed when cut-away portion 138 goes into
roller 140, which is mounted on pin 126 of swinging member 120.
Bridge 130 may be made of a metallic material, for example,
austenitic stainless steel.
[0034] As shown in FIG. 8, roller 140 is roughly cylindrical, with
the diameter of it's opening slightly larger than the exterior
diameter of pin 126. The exterior diameter of the roller is
slightly smaller than the gap between the sliding surfaces 138 of
bridge 130. Roller 140 may be made of a metallic material, for
example, martensite stainless steel.
[0035] In this section we shall explain how this embodiment
operates.
[0036] When the internal combustion engine operates, a negative
intake pressure is created according to its rate of revolution and
the openness of its throttle, and then the pressure is controlled
by a magnetic valve to transmit it to the actuator 50. The actuator
50 operates according to this pressure. Rod 52 moves forward and
back in the axial direction (to the right and left in FIG. 1)
according to the magnitude of the negative intake pressure. When
rod 52 operates, link member 54 rotates on shaft 124 of swinging
member 120 in response. As can be seen in FIG. 1, link member 54,
which is shown by solid lines, is in contact with bolt 56a on the
top of stop 56. At this point nozzle vanes 104 are in the open
position, the position which produces the maximum nozzle opening.
When the engine is operating at low r.p.m., or the throttle is only
slightly open, actuator 50 draws back rod 52. As rod 52 draws as
far back as it can go, link member 54 moves into a position in
which it is in contact with bolt 56b on the lower portion of stop
56, as shown by the dotted lines. At this point nozzle vanes 104
are in the position which produces the smallest nozzle opening.
[0037] In this way the linear movement of rod 52 is converted by
link member 54 into the swinging motion of swinging member 120. Pin
126 of member 120 moves in an arc around axis O of shaft 122 as
shown in FIGS. 4 and 5. At this point pin 126 and roller 140 are in
cut-away portion 138 in bridge 130, and the pin is between roller
140 and surface 138a. It slides upward and downward against bridge
130 in the relationship shown in FIG. 9, i.e., it slides along the
axis of rotation of turbine 28. At the same time link plate 112
rotates around the circumference of boss 102a on mounting plate
102, with the rotary axis of turbine 28 as its center. When link
plate 112 rotates, lever 114, which is connected to link plate 112,
rotates along with nozzle vanes 104 with shaft 104a of vanes 104 as
its center.
[0038] The action of shafts 114a of lever 114 in holes 112d of link
plates 112 can be analyzed into action in the circumferential
direction around the rotational center O (FIG. 6) of lever 114 and
action in the radial direction. With this first embodiment, each of
the holes 112d which receive shafts 114a of lever 114 is formed
along a centerline r of the oblong hole 112d which describes a
given angle with respect to a radius R from the rotational center O
of link plate 112. When link plates 112 rotate, a component Fr,
which pushes each shaft 114a along the center line r of hole 112d,
is generated in the force F acting on lever 114 from link plate 112
at the point where shaft 114a is in contact with hole 112d. This
component Fr allows shafts 114a of lever 114 to move smoothly in
the direction of declined center line of the oblong holes 112d of
link plates 112. As a result, the load on actuator 50 is reduced.
In the prior art design, each hole 112d' was formed directly on a
radius, so either there was no force generated to move shafts 114a
in the direction of declined center line r within holes 112d' or
only a very small force. This design in the prior arts prevented
link plates 112 from operating smoothly.
[0039] In FIGS. 5 and 6, holes 112d of link plates 112 are oblong,
and the ends of the oblong holes are rounded. However, the
invention is not limited to this shape of holes only. Holes 112d
could also have a simple rectangular shape. Further, according to
the second preferred embodiment, the holes in link plates 112, as
indicated by reference number 112d" in FIG. 7, may be curved to
correspond to the course traced by shafts 114a of lever 114 when it
rotates around shaft 104a of nozzle vanes 104.
[0040] This design is applicable to a variable turbocharger which
is distinguished by the following features. The nozzle vanes are
connected to the link plates by means of shafts which are parallel
to the shaft of the nozzle vanes on the circumference of the link
plates. These shafts engage in oblong holes in the lever. Each of
the holes in the lever is curved along an arc tangent to a line
extending at a given angle with respect to a radius from the
rotational center of the link plate.
[0041] The oblong hole is provided on the circumference of link
plate 112, and it faces perpendicular to the nozzle shaft of nozzle
vane. The shaft 114a of lever 114 engages with the oblong hole 112d
and slides within the inner surface of the oblong hole. As
mentioned above, therefore, the shaft 114a can slide within the
oblong hole which is curved along an arc tangent to a line
extending at a given angle with respect to a radius from the
rotational center of the link plate.
[0042] With this second embodiment, each of holes 112d" of link
plates 112 is curved along an arc tangent to a radius r-extending
at a given angle with respect to a radius R from the rotational
center O of link plate 112. When the link plate rotates, the
component of the force which pushes shaft 114a in the direction of
radius R is greater than in the first embodiment. More
specifically, when the shape of each hole 112d" in link plate 112
corresponds to the course traced by shaft 114a of lever 114, shafts
114a of lever 114 can move even more smoothly in the radial
direction R within holes 112d" in link plate 112.
[0043] We disclosed only the limited preferred embodiments of the
invention, however, the scope of the invention is not limited only
to these disclosures, and the invention will cover any modification
which can be made by a person with ordinary skill in the art.
* * * * *