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Патент USA US2405048

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July 30, 1946;
W. T. NMZKERSQN
CENTRIFUGAL COMPRESSOR
Filed Nov. 18, 1944
2 Sheets-Sheet l
Nickeraonq
July 30, 19416.
w, T, NgQKERsQN
2,405,048
CENTRIFUGAL COMPRES SOR
Filed Nov. 18, 1944
2 Sheets-Sheet 2
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2,405,048
Patented July 30, 1946
UNITED STATES PATENT OFFICE
2,405,048
CENTRIFUGAL COMPRESSOR
Win?eld '1‘. Nickerson, Lynn, Mass, assignor to
General Electric Company, a corporation of New
York
Application November 18, 1944, Serial No. 554,024
4 Claims. (Cl. 230-127)
2
1
The present invention relates to centrifugal
compressors having an impeller for impelling me
dium to be compressed, a diiiuser for receiving
face as in any other diffuser, but, in contrast to
the normal diffuser arrangement, the exit or dis~
charge openings of my di?user'pas'sages are lo
medium impelled by the impeller and converting
cated in circumferentially spaced, substantially
part of its velocity energy into pressure energy.
and a scroll or discharge chamber for receiving
medium from the diiiuser and discharging it into
radial planes through the compressor and the
outlet portion of each passage is located on top
of the inlet or intermediate portion of an adja
a consumer.
cent passage.
For a better understanding of ‘what I believe to
The overall dimensions of such centrifugal
compressors are in part determined by the radial 10 be novel and my invention, attention is directed
to the following description and the claims ap
dimensions of the diffuser and also by the par
pended thereto in connection with the accom
ticular arrangement of the diffuser and the dis“
charge scroll. It is desirable, particularly in air
panying drawings.
In the drawings, Fig. 1 illustrates a turbosuper
craft when used as part of a turbosupercharger,
to keep these overall dimensions of the com 15 charger, partly in section, embodying my inven
tion for use on aircraft to supply compressed me“
pressor as small as possible in order to bring them
dium such as air to an internal combustion en
within the general limits of the overall dimen
gine, a cabin or like consumer for r'ompressed me
sions of the particular turbine driving the col.dium; Fig. 2 is a perspective, fragmentary view
pressor and thereby to produce a compact design
relatively light in weight. In the past, this has 20 of Fig. 1; Fig. 3 is a sectional view of a modi?ca
tion according to my invention; Fig. 4 is a sec-~
been accomplished in part by the provision of
tion along lines 1i-4 of Fig. 3; Fig. 3 is in part a
saw-toothed diffusers having sidewalls with saw
toothed outer portions to permit lateral discharge
‘section
are sections
along along
line 3-3
lines of5-5
Fig.and
4;; Figs.
3'45, 5respec
and
from the diffuser passages through the openings
in the sidewalls and by providing the discharge 25 tively, of Fig. ll; and Fig. T is a perspective frag
mentary view of Fig. 3.
scroll substantially laterally of the diffuser. With
The turbosupercharger comprises a turbine I
such arrangements it has been possible to reduce
having a bucket wheel 2 secured to an overhung
the outer dimensions of the discharge scroll sub
portion of a shaft 3 and a nozzle box 4 {or con
stantially to the outer dimensions of the diffuser.
An arrangement of this kind is disclosed in Pat
ent No. 2,289,231 to C. H. Auger et al., issued on
July 7, 1942, and assigned to the same as'signee as
the present application.
The object of my invention is to provide an im
proved construction and arrangement of turbo
superchargers in which the outer overall dimen
sions of the compressor are substantially equal
to or of the order of the outer overall dimensions
of the turbine.
Another object of my invention is to provide ‘
an improved centrifugal compressor in which the
di?user and the discharge scroll form a unitary,
ducting gases to the bucket wheel 2 and having
a ?anged inlet portion 5 for receiving such gases
from a suitable source, for example, the exhaust
manifold of an internal combustion engine (not
shown). The turbine constitutes a power agency
-, for driving a centrifugal compressor having
impeller 5 secured to a shaft 3 and located with;
in a casing which has two ?anged halves l, 8 5e;
cured together by a row of bolts 9. The casing
forms an inlet conduit l0, an impeller chamber
I l, a diffuser chamber l2 and a scroll or discharge
chamber l3. The impeller chamber l! is formed
between the two case halves l and 3, whereas the
compact structure of the small outer dimension.
the
inletdiffuser
conduitchamber
l0 and and
the other
the scroll,
chambers,
are all that
formed
A third object of my invention is the provision
of an improved construction and arrangement 45 solely by the casing half 3.
The casing half 1 has an inner ?ange-d porti"
of diffusers for centrifugal compressors with rela
tively long diffuser passages of relatively small
The
bearing
14 secured
ringii 15to
formay
a supporting
ringform
15 by
part
athe
plurality
ofintermednte
the of boltsof
por
radial length. Broadly, this is accomplished in.
accordance with my invention by a diiiuser in
which the diffuser passages curve gradually out~ 50 tion of the shaft 3, and the inner rim of the ring
!5 is sealed to the shaft by a suitable packing
wardly and axially from their inlets or entrances
E3 to preclude leakage of oil from the bearing 1?
toward their exits or discharge openings. In a
into the impeller chamber.
annular baifie 59
preferred embodiment, the entrances of a plu~
with an outer extension
is located between the
rality of circumferentially spaced diffuser pas»
sages are located on a cylinder or cylindrical sur 55 compressor casing and the nozzle box 4 to support
2,405,048
3
A.
the latter on the compressor casing and to reduce
heat radiation from the turbine to the com
pressor. The upper end of the shaft 3 in the
present example is supported on a bearing 2! cen
trally disposed within the compressor inlet con
duit l0 and held thereon by a plurality of circum
ferentially spaced webs 0r vanes 22, which latter
also serve properly to direct air or like medium
through the inlet conduit l9 towards the eye of
the impeller 6.
The diffuser, according to my invention, as
previously stated, forms an integral part of the
compressor casing, or one half thereof, and has
a plurality of spaced diifuser passages which
curve gradually outwardly and axially from the
inlets toward their respective exits. Fig, 2 shows
in perspective two diffuser passages 23 and 24.
These two passages are formed between circum
is disposed in the casing and supported on a
bearing 31 held by guide vanes 38 in the inlet 33
of the casing. The diffuser for conducting com
pressed medium discharged from the impeller
into the scrol1 and converting part of its velocity
energy into pressure energy comprises a plurality
of circumferentially spaced, overlapping diffuser
passages 39, 40, M. The passages are formed
between vanes 42, 43 (Fig. '7). The inlet ends
of the diffuser passages are located on a cylinder
like those in Figs. 1, 2 but the inlet edges of the
vanes 42, 43 are inclined whereas the inlet edges
of the vanes in Fig. 2 are substantially perpen
dicular to the casing or parallel to the axis of the
impeller. The inclined vanes 42, 43 assure a
smooth ?ow of compressed medium into the
inlets of the diffuser passages and their inclina
tion relative to the exit edges of the impeller
ferentially spaced vanes or partitions 25, 26 and
blades reduces pulsations, that is, sudden flow
21. In addition to these vanes which form side~ 20 changes during operation as the impeller exit
walls of the passages 23, 24, each passage has a
edges pass the diffuser vane inlet edges. The
bottom and a top. Thus, the passage 23 has a
inclination of the diffuser vanes towards the
bottom 28 and a top 29, The adjacent or suc
axis decreases from the inlets towards the out
ceeding passage 24 has a bottom 36 and a top 3!.
lets of the diffuser passages as best seen from‘ a
From a consideration of Fig. 2, it will be readily 25 comparison between Figs. 5, 6, '2'. The inclina
seen that the bottom 28 of the ?rst diffuser pas
tion is a maximum at the inlet and a minimum
sage 23 merges gradually into the top 3! of the
at the outlet of the diffuser passages where the
adjacent or second diffuser passage 24. In other
vanes merge into the wall of the scroll. At the
words, the bottom of each diffuser passage forms
outlets of the diffuser passages the vanes "are
part of the top of a succeeding passage or, vice
substantially axial and merge gradually into the
versa, the top of each diffuser passage forms-a
bottom and top parts of the passages. The cor
part of the bottom of a preceding diffuser pas
ners between these parts and the vanes are
sage. Furthermore, each vane 25, 26, 21 merges
rounded (Fig. 3). In the arrangement of Fig. 1,
gradually into and forms part of, or is partly
adjacent passages overlap each other partly
formed by the outer wall of the scroll or dis
charge casing. The bottom of each passage also
merges into and forms part of the scroll. In
other words, each passage has a sidewall and a
only near their outlets whereas in the modi?ca
tion of Figs. 3 to 7, as best shown in Fig. 7, each‘
diffuser passage has an outlet overlapping com
pletely a succeeding passage and having an inter
bottom merging into and forming part of the
mediate part overlapped completely by a pre-‘
scroll. Each diffuser vane, as pointed out above, 40 ceding passage. The elimination of sharp cor
has an inner portion separating two adjacent
ners between the diffuser vanes and top and bot
passages, an outer portion merging into the wall
tom walls reduces friction losses of ?uid passing
therethrough.
of the scroll and, in addition, each vane has an
inner upper portion or extension which forms an
Having described the method of operation of
inner sidewall of a passage. Thus, in Fig. 2, the 4: my invention, together with the apparatus which
vane 26 has an inner portion separating the pas
I now consider to represent the best embodiment
sages 23, 24. The same vane has an outer por
thereof, I desire to have it understood that the
tion merging into the wall of the scroll and, in
apparatus shown is only illustrative and that
addition, the vane 26 has an inner upper por
the invention may be carried out by other means.
tion or extension which forms the inner side 50
What I claim as new and desire to secure by
wall of the passage 23. The exit or discharge
Letters Patent of the United States is:
opening of each diffuser passage is located sub
1. In a centrifugal compressor, a casing hav
stantially in a radial plane through the compres
ing two halves secured together and de?ning an
sor axis. Also, the exit of each diffuser passage
impeller chamber therebetween, one of the halves
is axially spaced from and located at least partly
defining a central axially extending compressor
above an intermediate part of a succeeding pas
inlet conduit and a diffuser and discharge scroll,
The center lines of diffuser passages of
said scroll being axially spaced from the impeller
the kind described are three-dimensional curves
sage.
exit and located entirely on the compressor inlet
side of the diffuser, said scroll at its largest cross
of skewed or helical character.
The curvature
is substantially gradual from the inlet towards 60 section merging into and being partly formed
the outlet of each passage. A particle passing
by the wall of the compressor inlet conduit, said
through a passage moves from the entrance
diffuser including a plurality of overlapping dif
radially outward and simultaneously circumfer
fusing passages arranged to direct ?uid dis
entially and axially,
charged from the impeller exit into the scroll
In a diffuser of this kind the outer dimensions 65 with a velocity having substantial tangential and .
of the scroll may be made substantially equal
axial components, said diffusing passages having
to the outer dimensions of the diffuser and the
circumferentially spaced inlets and outlets, the
passages of the latter merge gradually into the
inlets of the diffusing passages being located sub--'
scroll and are of comparative short radial length.
stantially on a cylinder surrounding and adja-'
The modi?cation illustrated in Figs. 3 to 7 in 70 cent the impeller exit, and the outlets of the pas-'
clusive comprises a casing having two halves 3|
sages being axially and radially spaced from their
and 32 corresponding to the two halves 8 and 7
respective inlets and lying within the discharge
respectively of Fig. 1. The casing half 32 forms
scroll, the outlets being also located in circum
an inlet 33 and a combined discharge scroll and
section 34. An impeller 35 secured to a shaft 36
ferentially spaced planes substantially parallel
to the compressor axis.
'
2,405,048
A diffuser for a centrifugal impeller having
walls forming a plurality of separate diffusing
passages arranged to receive ?uid from the im
peller and discharge it with a velocity having sub
stantial tangential and axial components, each
passage having an inlet and an outlet with the
inlet located on a cylinder around the axis of the
diffuser and the outlet radially and axially spaced
6
walls, a bottom, and a top axially spaced from
the bottom, the inner sidewall of each passage
merging gradually into and forming a portion
of the outer sidewall of the next succeeding pas
sage, and the bottom of each passage merging
gradually into and forming part of the top of the
next succeeding passage.
4. A diffuser for a centrifugal impeller having
walls forming a plurality of separate overlapping
from the inlet and located substantially in a plane
parallel to the axis of the diffuser, the outlet por is) diifusing passages, each passage having an inlet
lying on a cylinder adjacent and surrounding the
tion of each passage being axially adjacent and
impeller exit and an outlet ciroumferentlally and
overlapping completely an intermediate portion
radially and axially spaced from the inlet, each
of the next succeeding passage,
passage having circumferentially spaced substan
3. A diffuser for a centrifugal impeller, com
tially radially extending walls inclined to the axis
prising walls forming a plurality of separate over
of the diffuser, a radially inner sidewall extend
lapping diffusing passages for receiving fluid from
ing axially and tangentially from the inlet to
the impeller, each passage having an inlet lying
the outlet and .being substantially perpendicular
on a cylinder adjacent and surrounding the im
to said inclined walls, and an outer sidewall ra
peller exit and an outlet circumferentially and
radially and axially spaced from the inlet and it) dially spaced from the inner sidewall and form
ing a portion of the scroll, the inner portion of
arranged to discharge fluid into the scroll with
said inclined walls being common to adjacent dif
a velocity having substantial tangential and axial
fusing passages.
components, each passage having circumferen
WINFIELD T. NICKERSON.
tially and radially spaced inner and outer side
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