U.S. patent number 3,734,650 [Application Number 05/139,156] was granted by the patent office on 1973-05-22 for exhaust-gas driven turbochargers.
This patent grant is currently assigned to Aktiengesellschaft Kuhnle, Kopp & Kausch. Invention is credited to Dieter Bergmeier, Hans Joachim Klaue, Josef Reisacher.
United States Patent |
3,734,650 |
Reisacher , et al. |
May 22, 1973 |
EXHAUST-GAS DRIVEN TURBOCHARGERS
Inventors: |
Reisacher; Josef (Frankenthal,
DT), Klaue; Hans Joachim (Frankenthal, DT),
Bergmeier; Dieter (Heidelberg, DT) |
Assignee: |
Aktiengesellschaft Kuhnle, Kopp
& Kausch (Frankenthal, DT)
|
Family
ID: |
27182570 |
Appl.
No.: |
05/139,156 |
Filed: |
April 30, 1971 |
Foreign Application Priority Data
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May 2, 1970 [DT] |
|
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P 20 21 601.7 |
Aug 18, 1970 [DT] |
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P 20 4 901.2 |
May 2, 1970 [DT] |
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P 20 21 602.8 |
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Current U.S.
Class: |
417/407; 415/205;
415/225 |
Current CPC
Class: |
F02C
6/12 (20130101); F01D 9/026 (20130101) |
Current International
Class: |
F01D
9/02 (20060101); F02C 6/12 (20060101); F02C
6/00 (20060101); F04b 017/04 () |
Field of
Search: |
;417/207
;415/205,213 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,057,137 |
|
May 1959 |
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DT |
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750,387 |
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Jun 1956 |
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GB |
|
Primary Examiner: Husar; C. J.
Claims
What we claim is:
1. An exhaust gas turbocharger, for use with internal combustion
engines, comprising turbine and compressor wheels arranged on a
common shaft; said turbine wheel having guide blades structured to
be traversed by gases diagonally from the outside of said turbine
wheel to the inside thereof; said blades having inlet edges
substantially inclined, so that the direction of an entering gas
flow, as projected in a meridian plane, is perpendicular to said
inlet edges, as projected in the same meridian plane; the
cross-section of said turbine wheel guide blades being arranged
radially in sectional planes perpendicular to the turbine wheel
axis; said turbine wheel guide blades forming, at the inlet edge,
an entrance angle of less than 90.degree. with respect to the
turbine wheel axis; a housing for said turbine wheel in the form of
a single-flow spiral casing for gas admission to said turbine wheel
over the entire circumferential surface thereof; and at least two
gas conduits connecting respective engine cylinders into said
single-flow spiral casing, said gas conduits being joined at said
spiral casing in a manner such that the combined inlet cross
section of said conduits into said apiral casing is only slightly
larger than the cross section of each gas conduit at the ends
thereof connected to said spiral casing.
2. An exhaust gas turbocharger according to claim 1, in which the
blades (2) of the turbine wheel have at the inlet edge (4) an
entrance angle between 45.degree. and 70.degree..
3. An exhaust gas turbocharger, according to claim 1, which in that
the inlet edges (4) of said blades (2) of the turbine wheel assume
an aerodynamic form and are streamlined in profile.
4. An exhaust gas turbocharger, according to claim 1, which in that
the outside diameter (D2) at the outlet edge (16) of each blade (2)
of said turbine wheel (1) is the maximum diameter of the turbine
wheel.
5. An exhaust gas turbocharger according to claim 1, which in that
the inlet cross section (Fsp) at the inlet (3) of said single-flow
spiral casing (25) is by 5 to 15 percent larger than the cross
section (Fp) at the end of each of said gas lines coming from said
engine.
6. An exhaust gas turbocharger, according to claim 1, which in that
the smallest distance ro of the direction of the entering gas flow
from the axis of rotation is at most equal to 1.0 to 1.4 times the
mean wheel radius (rl) at the inlet ledge (4) of said blades (2) of
said turbine wheel (1)
7. An exhaust gas turbocharger according to claim 1, in which the
distances (Rs) of the centers of gravity of the cross sections of
the volute casing (7) from the shaft axis of rotation are kept as
small as possible in all meridian sections.
8. An exhaust turbocharger according to claim 1, in which a radial
diffuser (6) communicates with the wheel outlet of the turbine.
9. An exhaust gas turbocharger according to claim 1, in which the
spiral turbine casing (7) and radial diffuser (6) are integrally
connected with a bearing housing (8).
10. An exhaust gas turbocharger according to claim 1, in which the
mean wheel diameter (D12) at the outlet edge (13) of each blade
(12) of the compressor wheel (37) is less than 88 percent of the
maximum outer diameter (D2) of the blade (2) of the turbine wheel
1.
11. An exhaust gas turbocharger, according to claim 10, in which
the compressor wheel (37) is diagonally traversed from the center
to the periphery of said wheel.
12. An exhaust gas turbocharger according to claim 10, in which the
outlet edges (13) of the blades (12) of the compressor wheel (37),
projected into meridian planes, are substantially perpendicular to
the direction (38) of the flow of air passage projected into the
same meridian planes.
13. An exhaust gas turbocharger, according to claim 10, in which
the cross sections of the blades (12) of the compressor wheel (37)
are arranged radially in sectional planes perpendicular to the
wheel axis.
14. An exhaust gas turbocharger according to claim 10, in which
each of the blades (12) of the compressor wheel (37) forms at the
respective outlet edge (13) an outlet angle .beta.2 of less than
90.degree..
15. An exhaust gas turbocharger, according to claim 10, in which
the mean outlet diameter (D12) of the compressor wheel (37) is at
most equal to the outer diameter (D11) of the compressor inlet edge
(26).
16. An exhaust gas turbocharger, according to claim 1, in which
each outlet edge of said compressor wheel and each inlet edge of
said turbine wheel projects axially inwardly beyond the axially
inner wall of the respective wheel.
Description
SUMMARY OF THE INVENTION
The invention concerns a waste or exhaust gas turbo-charger for use
in connection with internal combustion engines in which a
turbo-charger is operatively connected a turbine- and a compressor
wheel, preferably via a common drive shaft.
Known waste gas turbo-superchargers for internal combustion engines
are adjusted to the average energy per time unit of the exhaust
gases which emanate from respective cylinders of an internal
combustion engine.
With relatively low outputs and correspondingly small amounts of
exhaust gases, the turbine of the gas turbo-charger is designed as
a "centripetal turbine," which is traversed in radial direction
from the outside or exterior to the inner part of the turbine blade
wheel from where these gases issue axially. These centripetal
turbines, however, are not adapted to a periodically greatly
varying or changing energy supply in order to achieve optimal
employment thereof. The form of the blade wheel, in particular the
form of its blades and those of the compressor wheel, is designed
and developed according to certain viewpoints taking into
consideration only turbines to which gases of constant energy are
fed and administered.
Compressor wheels of known gas turbo-superchargers of this kind are
designed generally as radial wheels whose diameters according to
the state of the art should be as far as possible equal to the
diameter of the turbine wheel.
It is therefore an object of the invention to provide means
overcoming heretofore known constructional disadvantages and
considerably improving the design of gas turbo-superchargers in
such a way that varying energy supply is reckoned with, and its
utilization is considered for the purpose of greater efficiency
during the operation of these engine cylinders.
Besides these considerations and advantages resulting therefrom,
the gas turbo-supercharger according to the invention is lighter in
weight and smaller than known structures of gas
turbo-superchargers. The reduction in weight has the further
advantage that smaller quantities of expensive construction
material is employed, so that the exhaust gas turbo-supercharger
according to the invention is more economical and less expensive to
produce than known exhaust gas aggregates of this type.
Gas turbo-superchargers for supercharging piston-driven internal
combustion engines, where the turbine- and the compressor wheels
are arranged on a common shaft, are known in the art, but there
remains still the problem to be solved pursuant to this invention,
namely, that the turbine wheel is to be traversed diagonally from
the exterior to the inner part thereof so that the inlet edges of
the blades of the turbine wheel, projected in meridian planes,
extend substantially perpendicularly to the direction of the
entering gas current, projected into the same meridian plane, and
further, that the blade cross sections of the turbine wheel are
radially arranged in sectional planes normal to the axis. The
blades of the turbine wheel form at the inlet edge an entrance
angle of less than 90.degree., while the turbine housing is
designed as a single-flow spiral housing or casing admitting the
contemplated medium or fluid to the turbine wheel over its entire
circumferential surface, on whose entrance part are joined at least
two exhaust gas pipe lines emanating from the cylinders of the
internal combustion engine in such a way that the inlet
cross-section at a tongue-shaped guide edge of the single flow
spiral casing is only slightly larger than the cross-section at the
discharge end of each individual exhaust gas pipe lines.
These and other objects and advantages result from the provision of
means affording a highly economical exhaust gas and like
turbo-supercharger, which is reduced in dimensions and does not
take up any considerable space.
The various features of novelty which characterize the invention
are pointed out with particularity in the claims annexed to and
forming a part of this disclosure. For a better understanding of
the invention, its operating advantages and specific objects
attained by its uses, reference should be had to the accompanying
drawing and descriptive matter in which there is illustrated a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS
In the drawings:
FIG. 1 is an axial section through an exhaust gas turbo-charger
embodying the invention.
FIG. 2 shows, in a diagram, pressure conditions of the exhaust gas
arriving at the turbine as related to the crank angle.
FIG. 3 is a schematic representation of the entrance part of a set
of blades of a known radial flow turbine and its associated
velocity vector diagram.
FIG. 4 illustrates schematically the dependence of the efficiency
on the characteristic of a radial flow-turbine according to FIG.
3.
FIG. 5 is a schematic representation of the entrance part of a
blade set for a diagonal-flow turbine pursuant to the invention, as
well as the velocity vector diagrams associated therewith.
FIG. 6 shows, in a diagram, the dependence of the efficiency on a
speed coefficient of an exhaust gas turbo-charger according to FIG.
5.
FIG. 7 is a section taken along the line 7 -- 7 of FIG. 1;
FIG. 8 is a section taken along line 8--8 of FIG. 7.
FIG. 9 shows a detail on an enlarged scale of a left-hand portion
of FIG. 1, to which reference is had in the description.
FIG. 10 illustrates a velocity vector diagram derived from FIG.
9.
FIG. 11 shows, in development, a portion of the blade wheel of FIG.
9.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now more specifically to the drawings and, in particular,
to FIG. 1, there is disclosed a turbine wheel 1 with blades 2. The
broken line 3 denotes the path of a central filamentous flow line,
(circularly projected in axial section of FIG. 1). Gas admission to
turbine wheel 1 occurs diagonally in the direction 36. The flow
passage likewise takes place substantially diagonally to the
represented meridian section.
The turbine wheel 1 projects, at the inlet edge 4 of blade 2, by an
amount LU in the direction of bearing 14 with respect to the rear
wall 5 of wheel 1, so that the wheel length L is extremely small in
the direction of the axis and the center of gravity of wheel 2 is
displaced toward bearing 14 of shaft 15. This arrangement causes
sufficient quietness in the rotor run and operation. The turbine
wheel is thus lighter in weight so that it is less expensive,
because of the high price of its employed high
temperature-resistant material.
The inlet edge 4 of the wheel is inclined by the angle .beta..sub.3
relative to the direction of the axis of rotation. This has the
effect that:
1. the mean diameter D1 at the inlet edge 4 is kept smaller than
the maximum diameter D.sub.2 at the outlet edge 16; and further
2. the length L of the wheel is reduced by the difference between
the length of the inlet edge 4 and the measure of projection in
respect to the axis thereof, so that material will be saved.
If a lot of energy is available at the entrance into the turbine,
that is, if the pressure gradient in the turbine is great and if
large amounts of exhaust gas pass or flow through the turbine, the
velocity, with which the gas flows out of blades 2, is very high.
Such high outlet velocities must be allowed in order to obtain very
small wheel diameters and thus less expensive turbine wheels. The
circumferential component of this high outlet velocity can be
utilized in a radial diffuser 6. By recovering a portion of the
outlet velocity, a pressure below atmospheric pressure is obtained
in the space between outlet edge 16 and closure cover 9.
The outside diameter D2 of outlet edge 16 of turbine wheel 1 is the
maximum diameter of wheel 1. This has the advantage that the spiral
casing 7, if necessary together with the discharge spiral casing
defining a diffuser 6, can be connected rigidly or difficulty
detachably with bearing housing 8 or even be made integral with the
latter. Nevertheless, the turbine wheel 1 can be disassembled in
the direction toward the right side. Cover 9 may be kept relatively
small. Under certain circumstances, wheel 1 can also be taken off
through a centrally arranged short exhaust pipe flange (not
shown).
In the diagonally traversed turbine wheel 1, according to the
invention, the mean diameter D1 is smaller than the outside
diameter (maximum diameter) D2 of outlet edge 16. This is due to
the fact (as pointed out herein above) that the inlet edge 4 is
obliquely cut off at an angle .beta..sub.3 . This has the advantage
that, at an equal cross sectional area 25 of spiral casing 7,the
radius Rs of the center of gravity of this cross-sectional area 25
diminishes. The spiral casing 7 is thus kept smaller and cheaper in
its construction.
The left portion of FIG. 1 shows the compressor wheel 37 with
blades 12 for air flow traversal from the inside toward the
peripheral edge 13 or outside. The mean diameter D12 of outlet edge
13 of blades 12 should not be greater than 88 percent of the outer
diameter (maximum diameter) D2 of the outlet edge 16 of turbine
wheel 1.
The compressor wheel 37, as shown, is traversed by air diagonally,
i.e., it is administered axially, the flow taking place between
edge 26 and outlet edge 13 in diagonal direction 38. The outlet
edge 13 is so inclined relative to the direction of the axis of
rotation by an angle .beta.4 that it extends perpendicularly to the
direction 38 of the escaping or outflowing air. In the same manner
as indicated for the turbine wheel 1, in the right hand part of
FIG. 1, the outlet edge 13 of blade 12 of compressor wheel 13 could
also project, with respect to the rear wall of this wheel, by a
certain amount in the direction of bearing 14 so as to obtain an
extremely small axial length of the wheel, a displacement of the
center of gravity of blades 12 toward the bearing 14 of shaft 15
and an improved quietness during running of compressor wheel
37.
According to FIG. 1, the maximum diameter (outer diameter) D11 of
inlet edge 26 of blades 12 of compressor wheel 37 is also greater
than the mean diameter D12 of outlet edge 13. This has the
advantage as already pointed out, that the maximum diameter (outer
diameter) D2 of the outlet edge 16 of the turbine wheel is greater
than the mean diameter D1 of the inlet edge 4.
FIG. 2 shows the pressure P in front of the turbine as a function
of the crank angle (from 630.degree. to 180.degree.) of one of the
cylinders of the internal combustion engine connected to the
exhaust gas turbo-supercharger. Each individual cylinder yields a
pressure course with periodically recurring maximum and minimum.
The entire pressure course ahead of the turbine is obtained by
superpositions of these pressure curves present in the individual
cylinders. The course of the curve can be approximated by a
step-like curve whose steps are designated with A, B, C, and D. The
upper dead center is designated with OT and the lower dead center
with UT.
Based on the periodically changing energy supply, according to FIG.
2, the utilization of the energy supplies for a known blade cascade
(FIGS. 3, 4) and for a blade cascade according to the invention
(FIGS. 5, 6) are compared.
FIG. 3 shows schematically, in the lower portion, the entrance
portion of the cascade of a conventional radial flow turbine
(centripetal turbine). In the upper part of FIG. 3, there is shown
the velocity vector diagram at the inlet edges of the blades for
two different pressures prevailing forward of the turbine, namely,
for the values A and C. C is,according to FIG. 2, the mean
pressure. The known radial flow turbine is constructed according to
this mean pressure C.
With this mean differential pressure C, one obtains a velocity of
gas flow C1C, taking into account the circumferential velocity U1
of the inlet edges of the blades, so that a relative velocity W1C
is obtained, which has the direction of the entrance portion of the
blades (that is, an entrance angle .beta.1 of 90.degree.). The
entrance of the gas current tangential to the entrance portion of
the blades, which is associated with the mean pressure C, has the
result that there is no entrance surge, so that an orderly flow can
take place between the blades. Accordingly, the mean pressure C at
the maximum efficiency lies on the associated efficiency curve of
FIG. 4, which indicates the efficiency K relative to the
coefficient U1/co, where U1 denotes the circumferential velocity of
the turbine wheel at the outer diameter thereof, and co the
theoretic absolute approach velocity of the wheel corresponding to
the pressure difference.
The maximum pressure A, however, lies on this curve at a far lower
efficiency. In the upper portion of FIG. 3, the absolute velocity
of the gas for this maximum pressure A is designated with C1A.
Taking into account the unchanged circumferential velocity U1, one
obtains a relative velocity W1A. Since this relative velocity W1A
forms an angle with the tangent of the blade, an entrance surge
appears so that no orderly flow can take place between the turbine
blades. This is a main reason why the maximum energy stage A can
only be utilized with a low efficiency in known turbines. From FIG.
4 a further reason for a low efficiency K of known exhaust gas
turbines may be gathered: the efficiency K of exhaust gas turbines
depends on the coefficient U1/co. Because the highest pressure
stage A is at a relatively low coefficient U1/co, the total
efficiency of known waste or exhaust gas turbines is relatively
low.
The aim of the present invention is therefore to improve the energy
yield of the turbo-supercharger.
Since the entrance angle .beta.1, according to FIG. 5, is less than
90.degree. according to the invention (preferably 45.degree. to
70.degree.), the turbine wheel blades 2 are so inclined at their
entrance portions 2a that this angle of inclination is equal to the
angle .beta.1 of the relative velocity W1A at the time of arrival
of the energy surge (corresponding to the highest pressure stage
A). Furthermore, the circumferential velocity U1 at the inlet edges
of the blades is,according to the invention, higher than the
corresponding circumferential velocity U1 of a known radial wheel
according to FIG. 3.
This has the result, according to FIG. 6, which shows,
corresponding to FIG. 4, the output or efficiency K as a function
of the coefficient U1/co, that the highest pressure stage A is
within the range of the maximum efficiency.
Furthermore,according to the invention the entrance edge 2a of each
blade 2 is given a profile which is streamlined. As a consequence
thereof, the degree of efficiency K is still very high even at
small deviations of the entrance angle from the ideal entrance
angle .beta.1 in respect to the relative velocity W. In the
efficiency curve according to FIG. 6, this can be seen to show that
the range of the maximum degree of efficiency of the impeller wheel
according to the invention is much wider than that of the maximum
degree of efficiency K of a known execution of a radial wheel
according to FIG. 3.
According to the invention, the blades 2 are curved in the range of
their inlet edges 2a in cylinder sections and so cut off (angle
.beta.3) that the inlet edge 4 in the meridian plane is
substantially perpendicular to the relative velocity W1 (direction
36). Consequently, the blade cross sections can be arranged
radially in sectional planes perpendicular to the axis, though the
entering angle .beta.1 is less than 90.degree..
In radially approached blade wheels (of the above-mentioned
centripetal turbines), the blade cross sections cannot be arranged
radially in sectional planes perpendicular to the axis with
entering angles under 90.degree.; this radial arrangement has
advantages with regard to the strength of the wheel which can
otherwise be obtained only with a radial wheel having blade
entering edges at right angles.
FIG. 7 shows a section taken along line 7--7 through the right half
of the turbine of FIG. 1. In FIG. 7 there is only represented the
mean radius r1 of wheel 1 which is equal to half the diameter D1
shown in FIG. 1.
FIG. 8 shows a section tbrough FIG. 7 along line 8--8.
In the embodiment of FIGS. 7 and 8, it is assumed that two exhaust
gas lines 40 and 41 come forth from the engine, which are to be so
combined at the turbine entrance housing, designed as a spiral
casing 7, that there exists a very favorable utilization of the
intermittently pulsating energy, namely:
a. a combination of the exhaust flows generally just ahead of the
turbine in order to conduct the impact in full strength to the
turbine, and
b. an admission over the entire turbine circumference to obtain the
best efficiency.
To this end, the turbine entrance housing is designed as a
single-flow spiral casing 7. FIG. 8 shows how the cross sections Fp
of the two gas lines 40 and 41, which are separated by the
partition 40a, pass over into the feed cross section Fsp of the
single-flow spiral casing 7 on tongue-like guide edge 30. The feed
cross section Fsp at tongue edge 30 of the single-flow spiral
casing 7 should be equal to each of the cross sections Fp of the
two exhaust gas conduits or lines 40 and 41, so that the velocity
Cp in cross section Fp passes over unchanged, that is, without any
substantial delay or acceleration and without any substantial
change in direction, directly into the velocity c1 (see also FIG.
5) in the feed cross section Fsp of spiral casing 7. In practice,
it was found feasible for constructional reasons to make Fsp by 5
to 15 percent larger than Fp; these values, however, should not be
exceeded. The velocity Cp of the exhaust gas inside the exhaust gas
line 40 or 41 must be so high that no exhaust gas can flow back
from the one gas line just carrying a gas pressure impact into the
other gas line.
The smallest distance r.sub.o of the direction of the gas current
entering with the velocity Cp from the axis of rotation should be
at most equal to the 1.0 - to the 1.4 fold of the mean wheel radius
r.sub.1 in order to avoid greater velocity variations of the waste
or exhaust gas current until it enters wheel 1.
FIG. 9 shows a detail of the left-hand portion of FIG. 1, hence
from the compressor wheel. This compressor wheel 37 carries wheel
blades 12 with the beveled or obliquely cut off (.beta.4) outlet
edge 13. FIG. 10 shows a velocity vector diagram at point E of
outlet edge 14. U.sub.2 is the circumferential velocity at point E,
C2 the absolute air outlet velocity, and W2 the relative velocity
of the outflowing air. One realizes that the exit angle .beta.2 is,
according to the invention, less than 90.degree., i.e., the blades
are inclined toward the rear at outlet edge 13 and against the
circumferential direction. Compressor blades inclined toward the
rear at the outlet (.beta.2 less than 90.degree.) have the
advantage that the charging pressure depends less on the volume
current than in blades with radially terminating ends.
For reasons of strength, the blades of the compressor wheel 37 are
so designed that the blade cross sections are arranged radially in
sectional planes perpendicular to the axis. That this is possible
in the compressor wheel traversed diagonally according to the
invention, in contrast to the conventional radial wheels, though
.beta.2 is less than 90.degree., will be explained on the basis of
FIGS. 9, 10 and 11, where FIG. 11 shows a portion of the
circumference of the wheel of FIG. 9 in developed form.
E is the point of outlet edge 13 on blade root 42. In the meridian
section seen in FIG. 9, the component W2m of the relative exit
velocity of the air appears at this point E. The velocity vector
diagram represented in FIG. 10 was turned about W2m into the plane
in which the velocity W2, with which the air issues from the
compressor wheel (relative velocity), appears in correct size. The
absolute exit velocity C2 and the circumferential velocity U2 at
point E, as well as the angles, appear also in FIG. 10 in their
correct size. It is assumed that blade root 42 is straight, in the
represented meridian section, between the points E' and E. From the
projection of E' into the plane of the velocity vector diagram
(FIG. 10) results in FIG. 10 the direction of W2, that is, the
angle B2, which is less than 90.degree.. Nevertheless, point F, for
example, is arranged radially above E', as it is illustrated in
FIG. 11, that is, the blade cross sections are arranged radially in
sectional planes perpendicular to the axis.
While a specific embodiment of the invention has been shown and
described in detail to illustrate the application of the principles
of the invention, it will be understood that the invention may be
embodied otherwise without departing from such principles.
* * * * *