U.S. patent application number 12/745351 was filed with the patent office on 2010-12-09 for turbocharger.
This patent application is currently assigned to IHI Corporation. Invention is credited to Yoshimitsu Matsuyama, Hiroshi Tange.
Application Number | 20100310363 12/745351 |
Document ID | / |
Family ID | 40755307 |
Filed Date | 2010-12-09 |
United States Patent
Application |
20100310363 |
Kind Code |
A1 |
Matsuyama; Yoshimitsu ; et
al. |
December 9, 2010 |
TURBOCHARGER
Abstract
Turbulence of fluid in a turbine impeller outlet is reduced with
a simple structure so as to improve efficiency of a turbine. In a
turbocharger comprising a turbine housing 1 having a scroll passage
8 outwardly of an exhaust nozzle 9 which in turn is arranged
outwardly of a turbine impeller 4 rotatably supported on a bearing
housing 3, the exhaust nozzle 9 having a plurality of nozzle vanes
15 between front and rear exhaust introduction walls on sides of
the bearing and turbine housings 3 and 1, respectively, a vane
shaft for each of the nozzle vanes 15 extending at least through
the front exhaust introduction wall 10 and being rotatably
supported, pressing means 23 is arranged between the respective
vane shafts 16 and the bearing housing 3 to urge the vane shafts 16
toward the rear wall 11 to displace the nozzle vanes 15 toward the
rear wall 11.
Inventors: |
Matsuyama; Yoshimitsu; (
Tokyo, JP) ; Tange; Hiroshi; (Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
IHI Corporation
Tokyo
JP
|
Family ID: |
40755307 |
Appl. No.: |
12/745351 |
Filed: |
November 12, 2008 |
PCT Filed: |
November 12, 2008 |
PCT NO: |
PCT/JP08/03282 |
371 Date: |
May 28, 2010 |
Current U.S.
Class: |
415/212.1 |
Current CPC
Class: |
F01D 17/165 20130101;
F02B 37/24 20130101; F05D 2220/40 20130101; Y02T 10/12 20130101;
Y02T 10/144 20130101 |
Class at
Publication: |
415/212.1 |
International
Class: |
F01D 9/00 20060101
F01D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2007 |
JP |
2007-320719 |
Claims
1. A turbocharger with a bearing housing having a scroll passage
outwardly of an exhaust nozzle which in turn is arranged outwardly
of a turbine impeller rotatably supported on the bearing housing,
said exhaust nozzle having a plurality of nozzle vanes between
front and rear exhaust introduction walls on sides of the bearing
and turbine housings, respectively, a vane shaft for each of said
nozzle vanes extending at least through the front wall and being
rotatably supported, characterized in that it comprises pressing
means arranged between the respective vane shafts and the bearing
housing for urging the respective vane shafts toward the rear wall
to displace the nozzle vanes toward the rear wall.
2. A turbocharger as claimed in claim 1, wherein said pressing
means is a disc spring between the vane shafts and the bearing
housing.
3. A turbocharger as claimed in claim 1, wherein said pressing
means is a coiled spring between each of the vane shafts and the
bearing housing.
4. A turbocharger as claimed in claim 1, wherein each of said
nozzle vanes is supported in a cantilever manner by the vane shaft
on one side of the vane extending through the front wall.
5. A turbocharger as claimed in claim 1, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane extending through the front and rear walls,
respectively.
6. A turbocharger as claimed in claim 1, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane, one of the vane shafts extending through the front
wall, the other vane shaft being embedded in the rear wall.
7. A turbocharger as claimed in claim 2, wherein each of said
nozzle vanes is supported in a cantilever manner by the vane shaft
on one side of the vane extending through the front wall.
8. A turbocharger as claimed in claim 3, wherein each of said
nozzle vanes is supported in a cantilever manner by the vane shaft
on one side of the vane extending through the front wall.
9. A turbocharger as claimed in claim 2, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane extending through the front and rear walls,
respectively.
10. A turbocharger as claimed in claim 3, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane extending through the front and rear walls,
respectively.
11. A turbocharger as claimed in claim 2, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane, one of the vane shafts extending through the front
wall, the other vane shaft being embedded in the rear wall.
12. A turbocharger as claimed in claim 3, wherein each of said
nozzle vanes is dually supported by vane shafts on opposite sides
of the vane, one of the vane shafts extending through the front
wall, the other vane shaft being embedded in the rear wall.
Description
TECHNICAL FIELD
[0001] The present invention relates to a turbocharger which is
simple in structure and which can reduce turbulence of fluid in a
turbine impeller outlet to improve efficiency of a turbine.
BACKGROUND ART
[0002] FIG. 1 shows a conventional variable displacement
turbocharger to which the invention is applied. In the
turbocharger, turbine and compressor housings 1 and 2 are
integrally assembled through a bearing housing 3 by fastening bolts
3a and 3b, a turbine impeller 4 in the turbine housing 1 being
connected to a compressor impeller 5 in the compressor housing 2 by
a turbine shaft 7 rotatably supported via a bearing 6 in the
bearing housing 3.
[0003] As shown in FIG. 2 in enlarged scale, the bearing housing 3
is provided, on its turbine housing 1 side, with an exhaust nozzle
9 by which fluid (exhaust gas) introduced into a scroll passage 8
in the turbine housing 1 is guided to a turbine impeller 4.
[0004] The exhaust nozzle 9 comprises front and rear exhaust
introduction walls 10 and 11 respectively on sides of the bearing
and turbine housings 3 and 1 and integrally assembled together with
a required distance between them by, for example, three fixing
members 12 arranged circumferentially. Upon assembling of the
turbine and bearing housings 1 and 3, an attachment member 13 fixed
on a front surface of the front wall 10 (side surface of the
bearing housing 3) is clamped by the housings 1 and 3 to fix the
exhaust nozzle 9. Upon the assembling, the exhaust nozzle 9 is
positioned with respect to the bearing housing 3 by a positioning
pin 14.
[0005] Arranged between the front and rear walls 10 and 11 are a
plurality of nozzle vanes 15 each rotatably supported at least on
the front wall 10 by a vane shaft 16 extending through the front
wall 10. In the example shown in FIG. 2, each of the nozzle vanes
15 is supported in a cantilever manner by the vane shaft 16
arranged on the vane 15 on the side of the bearing housing 3 to
extend through the front wall 10. Alternatively, as shown in FIG.
1, each of the nozzle vanes 15 may be dually supported by vane
shafts 16 and 28 on opposite sides of the vane 15 extending through
the front and rear walls 10 and 11, respectively.
[0006] In FIG. 1, reference numerals 17a, 17b, 17c and 17d
designate a linked transmission mechanism for varying an opening
angle of the nozzle vanes 15 for capacity control; and 18, a scroll
passage in the compressor housing 2.
[0007] Provided between the turbine housing 1 and the rear wall 11
of the exhaust nozzle 9 is a gap 19 which is, by nature, is
unwanted and which is however is provided for countermeasure to,
for example, possible thermal deformation of the turbine housing 1
between during being hot and during being cold and possible
variations in accuracy of parts to be assembled.
[0008] The gap 19 may disadvantageously cause the exhaust gas in
the scroll passage 8 to vainly leak to a turbine impeller outlet
20, resulting in lowering of turbine efficiency. Thus, in order to
block the gap 19, it has been proposed to arrange sealing piston
rings 21 between an outer surface of a downstream extension 11' of
the rear wall 11 and an inner surface 1' of the turbine housing 1
confronting the extension 11' so as to prevent the gas leakage and
absorb thermal deformation (see Patent Literature 1).
[0009] In Patent Literature 1, as best shown in FIG. 2, formed on
the outer periphery of the extension 11' of the rear wall 11 is an
annular groove 22 into which generally two sealing piston rings 21
are inserted with their closed gaps being not aligned or overlapped
with each other, thereby providing a sealing device. The piston
rings 21 are pressed at their outer peripheries against the inner
surface 1' of the turbine housing 1 by spring force of the piston
rings themselves to prevent the gas leakage.
[0010] [Patent Literature 1] JP 2006-125588A
SUMMARY OF INVENTION
Technical Problems
[0011] In the conventional turbochargers, as shown in FIG. 2, some
sealing device has been devised to prevent gas leakage from the gap
19; however, even with such devised sealing device, it is difficult
and limitative to substantially improve turbine efficiency.
[0012] Thus, the inventors have made various researches and
experiments on factors other than the gas leakage affecting the
turbine efficiency to find out that the more the exhaust gas in the
turbine impeller outlet 20 is turbulent, the more the turbine
efficiency is lowered and that the less the exhaust gas in the
turbine impeller outlet 20 is turbulent, the more the turbine
efficiency is improved.
[0013] The invention was made in view of the above and has its
object to provide a turbocharger which is simple in structure and
which can reduce turbulence of fluid in a turbine impeller outlet
to improve turbine efficiency.
Solution to Problems
[0014] The invention is directed to a turbocharger with a turbine
housing having a scroll passage outwardly of an exhaust nozzle
which in turn is arranged outwardly of a turbine impeller rotatably
supported on a bearing housing, said exhaust nozzle having a
plurality of nozzle vanes between front and rear exhaust
introduction walls on sides of the bearing and turbine housings,
respectively, a vane shaft for each of said nozzle vanes extending
at least through the front wall and being rotatably supported,
characterized in that it comprises pressing means arranged between
the respective vane shafts and the bearing housing for urging the
respective vane shafts toward the rear wall to displace the nozzle
vanes toward the rear wall.
[0015] In the turbocharger, said pressing means may be a disc
spring between the vane shafts and the bearing housing.
[0016] In the turbocharger, said pressing means may be a coiled
spring between each of the vane shafts and the bearing housing.
[0017] In the turbocharger, each of said nozzle vanes may be
supported in a cantilever manner by the vane shaft on one side of
the vane extending through the front wall.
[0018] In the turbocharger, each of said nozzle vane may be dually
supported by vane shafts on opposite sides of the vane extending
through the front and rear walls, respectively.
[0019] In the turbocharger, each of said nozzle vane may be dually
supported by vane shafts on opposite sides of the vane, one of the
vane shafts extending through the front wall, the other of the vane
shafts being embedded in the rear wall.
ADVANTAGEOUS EFFECTS OF INVENTION
[0020] According to a turbocharger of the invention which comprises
pressing means between the bearing housing and the respective vane
shafts of the nozzle vanes for urging the respective vane shafts
toward the rear wall to displace the nozzle vanes toward the rear
wall, a clearance between the nozzle vanes and the rear wall can be
minimized by the simple structure, resulting in advantageous effect
that turbulence of the fluid in the turbine impeller outlet can be
reduced to substantially improve efficiency of the turbine.
BRIEF DESCRIPTION OF DRAWINGS
[0021] FIG. 1 is a sectional side view showing a conventional
turbocharger;
[0022] FIG. 2 is a sectional side view showing the nozzle and its
vicinity in FIG. 1;
[0023] FIG. 3 is a sectional side view showing a nozzle and its
vicinity according to an embodiment of the invention;
[0024] FIG. 4 is a side view showing the disc spring in FIG. 3;
[0025] FIG. 5 is a sectional side view showing a nozzle and its
vicinity according to a further embodiment of the invention;
[0026] FIG. 6 is a sectional side view showing a further embodiment
of the vane shafts which support the nozzle vane;
[0027] FIG. 7 is a sectional side view showing a still further
embodiment of the vane shafts which support the nozzle vane;
[0028] FIG. 8 is a diagram for showing conditioning conventional
and claimed turbochargers to have substantially same pressure
ratios between upstream and downstream sides of turbine
impeller;
[0029] FIG. 9 is a diagram showing velocity distribution of exhaust
gas in radial positions in comparison of the conventional
turbocharger with the claimed turbocharger; and
[0030] FIG. 10 is a diagram showing turbine efficiency in
comparison of the conventional turbocharger with the claimed
turbocharger.
REFERENCE SIGNS LIST
[0031] 1 turbine housing [0032] 3 bearing housing [0033] 4 turbine
impeller [0034] 5 compressor impeller [0035] 8 scroll passage
[0036] 9 exhaust nozzle [0037] 10 front exhaust introduction wall
[0038] 11 rear exhaust introduction wall [0039] 15 nozzle vane
[0040] 16 vane shaft [0041] 20 turbine impeller outlet [0042] 23
pressing means [0043] 24 disc spring [0044] 27 coiled spring [0045]
28 vane shaft [0046] 28' vane shaft
DESCRIPTION OF EMBODIMENTS
[0047] Embodiments of the invention will be described in
conjunction with the attached drawings.
[0048] FIG. 3 shows an embodiment of the invention applied to the
turbocharger shown in FIG. 2 with nozzle vanes 15 being arranged
between front and rear exhaust introduction walls 10 and 11 of an
exhaust nozzle 9 and each being supported in a cantilever manner by
a vane shaft 16 arranged on a side of the vane 15 and extending
through the front wall 10, comprising pressing means 23 arranged
between a front end 16' (right end in FIG. 3) of the vane shaft 16
of each of the nozzle vanes 15 and a rear surface 3' of a bearing
housing 3 (between a nozzle link plate 16a referred to hereinafter
and the rear surface 3') to urge the respective vane shafts 16
toward the rear wall 11 to thereby keep the respective nozzle vanes
15 always in a displaced state toward the rear wall 11.
[0049] The pressing means 23 shown in FIG. 3 is in the form of a
disc spring 24 which urges the respective vane shafts 16 toward the
rear wall 11. As shown in FIG. 4, the disc spring 24 is
frustconical and has inner and outer peripheral edges 25 and 26
mutually offset with respect to an axis of the spring to thereby
provide a doughnut shape, an axial height H of the disc spring 24
with the frustconical shape being set to be greater than a distance
between the respective front ends 16' of the respective vane shafts
16 and the rear surface 3' of the bearing housing 3.
[0050] The respective front ends 16' of the vane shafts 16 extend
through and are retained by inner ends of nozzle link plates 16a
(shaft support members) arranged between the front wall 10 and the
rear surface 3' of the bearing housing 3. The respective nozzle
link plates 16a are pivoted about the vane shafts 16 by rotating a
drive ring (not shown); the respective vane shafts 16 (nozzle vanes
15) are rotated integrally with the respective nozzle link plates
16a through the pivotal movements of the nozzle link plates 16a.
Since the disc spring 24 is arranged in a compressed state between
the front ends 16' of the respective vane shafts 16 and the rear
surface 3' of the bearing housing 3, the elastic force of the disc
spring 24 causes the vane shafts 16 to be urged toward the rear
wall 11, the nozzle vanes 15 being displaced toward the rear wall
11.
[0051] FIG. 5 shows a further embodiment of pressing means 23 which
has a coiled spring 27 between respective front ends 16' of vane
shafts 16 and a rear surface 3' of a bearing housing 3 so as to
urge the respective vane shafts 16 toward a rear exhaust
introduction wall 11.
[0052] FIG. 6 shows a case where vane shafts 16 and 28 on opposite
sides of each of nozzle vanes 15 extend through front and rear
exhaust introduction walls 10 and 11, respectively, so that the
nozzle vanes 15 are dually supported by the vane shafts 16 and 28
on the walls 10 and 11; also in this case, pressing means 23
comprising a disc spring 24 or coiled springs 27 shown in FIG. 5
may be arranged between the front ends 16' of the vane shafts 16
and a rear surface 3' of a bearing housing 3 so as to urge the
respective vane shafts 16 toward the rear wall 11.
[0053] FIG. 7 shows a case where vane shafts 16 and 28' are
provided on opposite sides of each of nozzle vanes 15, one 16 of
the vane shafts extending through a front exhaust wall 10, the
other vane shaft 28' not extending through but being embedded in a
rear exhaust introduction wall 11 so that the nozzle vanes 15 are
dually supported by the vane shafts 16 and 28'; also in this case,
pressing means 23 comprising a disc spring 24 or coiled springs 27
as shown in FIG. 5 may be arranged between front ends 16' of the
vane shafts 16 and a rear surface 3' of a bearing housing 3 so as
to urge the respective vane shafts 16 toward the rear wall 11.
[0054] Mode of operation of the embodiments shown in FIGS. 3-7 is
as follows.
[0055] When the pressing means 23 comprising the disc spring 24
shown in FIGS. 3 and 4 or the coiled springs 27 shown in FIG. 5 is
arranged between the front ends 16' of the vane shafts 16 of the
nozzle vanes 15 and the rear surface 3' of the bearing housing 3,
the respective vane shafts 16 are always urged by the pressing
means 23 toward the rear wall 11, so that the respective nozzle
vanes 15 are retained in their displaced positions toward the rear
wall 11.
[0056] More specifically, there exist inherently clearances between
the nozzle vanes 15 and the front and rear exhaust introduction
walls 10 and 11 so as to make the nozzle vanes 15 pivotable and
rotatable; and the clearances may be different between individual
turbochargers. Then, as mentioned in the above, the respective vane
shafts 16 are urged by the pressing means 23 toward the rear wall
11, so that the respective nozzle vanes 15 are displaced toward the
rear wall 11 by the clearance. As a result, the respective nozzle
vanes 15 contact the rear wall 11 with the clearance between the
nozzle vanes 15 and the rear wall 11 being minimized.
[0057] In the embodiments shown in FIGS. 3, 6 and 7, the rear
surface 3' of the bearing housing 3 has a circumference in the form
of frustoconical surface 3a' (forwardly and outwardly tapered
surface). The disc spring 24 is arranged with its outer
circumference being between the frustoconical surface 3a' and the
nozzle link plates 16a and extending along the frustoconical
surface 3a'. This makes it easy to ensure a space for the disc
spring 24 without broadening the distance between the rear surface
3' and the nozzle link plates 16a.
[0058] On the conditioning that a conventional turbocharger
(conventional one) and a turbocharger of the invention (claimed
one) are made to have substantially same pressure ratios between
upstream and downstream sides of turbine impeller 4 as shown in
FIG. 8, the inventors determined velocity distribution of exhaust
gas at radial positions in turbine impeller outlet 20 through
numerical analysis. The results are shown in FIG. 9.
[0059] As is clear from FIG. 9, in comparison with the conventional
one, the claimed one has radially flattened flow velocity
distribution with less deviation. This means that the claimed one
has less turbulence of exhaust gas in turbine impeller outlet 20 in
comparison with the conventional one.
[0060] Moreover, turbine efficiency was compared between the
claimed and conventional ones through numerical analysis. As a
result, it was found out as shown in FIG. 10 that the claimed one
has turbine efficiency improved by about 10% relative to the
conventional one.
[0061] The exhaust gas in the scroll passage 8 passes through the
nozzle vanes 15 of the exhaust nozzle 9 into the turbine impeller
4. Because of such exhaust gas flow being a complex
three-dimensional stream, it is much difficult to find out factors
in turbulence of the exhaust gas in the turbine impeller outlet
20.
[0062] However, as mentioned in the above, when the clearance
between the respective nozzle vanes 15 and the rear wall 11 is
minimized by urging the respective vane shafts 16 toward the rear
wall 11, then the velocity distribution of the exhaust gas at
radial positions in the turbine impeller outlet 20 becomes
flattened to reduce the turbulence of the exhaust gas in the
turbine impeller outlet 20, whereby the turbine efficiency can be
improved. Thus, it was found out that the clearance between the
respective nozzle vanes 15 and the rear wall 11 is one of factors
affecting turbulence of the exhaust gas in the turbine impeller
outlet 20.
[0063] Thus, according to the invention, by the above-mentioned
simple structure that the pressing means 23 is arranged between the
bearing housing 3 and the respective vane shafts 16 of the nozzle
vanes 15, the nozzle vanes 15 are displaced toward the rear wall 11
to keep in the minimized state the clearance between the respective
nozzle vanes 15 and the rear wall 11, whereby the turbulence of the
fluid in the turbine impeller outlet 20 can be reduced to
substantially improve the efficiency of the turbine.
[0064] It is to be understood that the invention is not limited to
the above embodiments and that various changes and modifications
may be made without departing form the scope of the invention. For
example, though the sealing device in the form of the piston rings
21 for the gap 19 has been exemplified in the above embodiments,
there is no restriction or limitation on construction of the
sealing device.
INDUSTRIAL APPLICABILITY
[0065] A turbocharger according to the invention can be applied to
displace nozzle vanes toward a rear exhaust introduction wall to
minimize clearance between the respective nozzle vanes and the rear
wall, thereby reducing turbulence of fluid in a turbine impeller
outlet to improve efficiency of a turbine.
* * * * *