Structures of turbine scroll and blades

Details Structures of turbine scroll and blades Structures of turbine scroll and blades

2002-10-16

2004-06-01

Verdier, Christopher (Department: 3745)

Rotary kinetic fluid motors or pumps

Working fluid passage or distributing means associated with...

Casing having tangential inlet or outlet

C415S204000, C415S211100, C415S212100, C416S185000, C416S188000, C416S22300B, C416S22300B, C416S228000, C416S235000

Reexamination Certificate

active

06742989

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to structures of turbine scroll and blades. The turbine scroll forms the gas flow path for radial turbines used in turbochargers for internal combustion engines (exhaust gas turbocharger), small turbines, expansion turbines, etc., wherein the operating gas flows onto the turbine blades on the turbine rotor from the vortex-shaped scroll in the radial direction to impart rotational drive to said turbine rotor. The turbine blades are fixed on a rotor shaft for the compressor.
2. Description of the Related Art
Radial turbines are widely used in the relatively compact turbochargers (exhaust gas turbochargers) used in automobile engines and the like. The operating gas for the turbine flows in the radial direction from the vortex-shaped scroll formed inside the turbine casing to the turbine blades, causing the rotation of said turbine rotor, before flowing in the axial direction.
FIG. 11
shows an example of a turbocharger using a radial turbine. In the Figure,
1
represents the turbine casing,
4
the vortex-shaped scroll formed inside turbine casing
1
,
5
the gas outflow path formed inside turbine casing
1
,
6
the compressor casing, and
9
the bearing housing that links the turbine casing
1
and compressor casing
6
.
Turbine rotor
10
has a plurality of turbine blades
3
, which are evenly spaced and affixed to its outer circumference.
7
is the compressor,
8
the diffuser mounted at the air outlet of said compressor
7
, and
12
is the rotor shaft that links said turbine rotor
10
and compressor
7
.
11
is a pair of bearings mounted in the foregoing housing
9
, which support the foregoing rotor shaft
12
.
20
is the axis of rotation of the foregoing turbine rotor
10
, compressor
7
and rotor shaft
12
.
In turbochargers equipped with such radial turbines, exhaust gases from the internal combustion engine (not shown) enter the foregoing scroll
4
, where they flow along the swirl of said scroll
4
, which causes them to rotate as they flow in from the opening at the outside circumference of the turbine blades
3
toward said turbine blades
3
in the radial direction toward the center of turbine rotor
10
. After performing the expansion work upon said turbine rotor
10
, the gases flow in the axial direction outside of the device through gas outlet
5
.
FIG. 12
is a structural diagram showing the foregoing scroll
4
and surrounding area in a radial turbine. In the figure,
4
is the scroll,
41
the outer circumferential wall of said scroll
4
,
43
the inner circumferential wall, and
42
the side walls. Also,
3
represents the turbine blades,
36
the shroud side and
34
is the hub side for said turbine blades
3
.
The width &Dgr;R
0
in the radial direction of scroll
4
is formed to be of approximately the same dimensions as the width B
0
in the direction of the axis of rotation (scroll width ratio &Dgr;R
0
/B
0
=1).
FIG.
13
(A), FIG.
13
(B) show the area around a tongue formed in inner circumference of the gas inlet to the radial turbine; FIG.
13
(A) is a front view from a right angle to the axis of rotation, and FIG.
13
(B) is a view in the direction of the arrows on line B—B of FIG.
13
(A).
In the FIGS.
13
(A),
13
(B),
4
is the scroll,
44
is the edge surface of the opening to said scroll
4
,
45
the tongue formed on the inside circumference of the gas inlet,
45
a
is the tongue edge, the downstream edge of said tongue
45
, and
046
represents the tongue's downstream side walls, which are located directly downstream of tongue edge
45
a
of the foregoing scroll
4
.
The width between the walls of said tongue's downstream side walls
046
is either the same as the width of the foregoing tongue edge
45
a
, or a width that has been smoothly constricted from tongue edge
45
a
to follow the shape of the scroll
4
.
In the above described types of radial turbines, the gases inflowing into the vortex of the foregoing scroll are rotating as they flow into turbine blades
3
, and the velocity distribution of the inflowing gas varies in the height direction (Z direction) of turbine blades
3
.
To wit, due to the three dimensional boundary layer having a 15 to 20% height B
3
range at the foregoing input edge surface formed in the vicinity of inlet edge surface
31
(see
FIG. 12
) for the foregoing turbine blades
3
, the foregoing gas inflow velocity C, as shown in
FIG. 14
, has a circumferential direction component having a circumferential velocity C&thgr;, which is greater at the center of the foregoing inlet edge surface
31
, and which is lower at the square area on both ends of the blades
3
, i.e. the shroud side
36
and the hub side
34
. Also, as shown in
FIG. 11
, the radial direction component, which is the radial direction velocity C
R
, has a distribution in the height direction, which is lower in the center of the foregoing inlet edge surface
31
and higher at both edges, i.e. the shroud side
36
and the hub side
34
.
Then when distribution in the flow in the height direction at the inlet to the foregoing turbine blades
3
exists, in other words, when there is distortion in the flow, the flow loss at said turbine rotors increases, and this lowers the turbine's efficiency. To wit, the optimum relative angle of gas inflow &bgr;
1
, along with relative angle of gas inflow &bgr;
2
between the walls of inlet edge walls
31
, i.e. between the foregoing hub side
34
and shroud side
36
, in the center of the inlet for turbine blades
3
increases, so that near the foregoing hub side
34
and shroud side
36
, a difference develops in the relative angle of gas inflow &bgr;. In other words, as the gas impact angle (incidence angle) increases, the impact angle (incidence angle) also increases on the back side of turbine blades
3
from the gas (back pressure), which not only causes impact loss, but it increases the impact angle (incidence angle) at the foregoing hub side
34
and shroud side
36
, which adds to the secondary flow loss between the turbine blades to thereby lower the turbine's efficiency.
On the other hand, in the foregoing scroll
4
, which forms the inlet flow path to the turbine blades
3
, the shape of the scroll
4
causes a three dimensional boundary layer to be produced. As shown in FIG.
15
(B), the radial direction velocity C
R
in the height direction of turbine blades
3
, shows a velocity distribution which is lower at the center of the foregoing inlet edge surface
31
, and higher at the square areas on the two ends of the blades, in other words, on the shroud side
36
and the hub side
34
.
However, as shown for the conventional scroll
4
in
FIGS. 12
and
13
:
(1) the cross-sectional shape of the flow path of scroll
4
is approximately square, with the width dimension in the radial direction &Dgr;R
0
being the same as the width in the direction of the axis of rotation B
0
(scroll width ratio &Dgr;R
0
/B
0
=1).
(2) In the area on both sides of scroll
4
which connect to around both edges of turbine blades
3
, to wit the shroud side
36
and the hub side
34
, the side walls have a smooth surface.
(3) The width Bo in the direction of the axis of rotation of the scroll
4
flow is formed to be either constant, or diminished slightly toward the inside circumferential side.
These result in the following types of problems:
Due to that structure, the above described three dimensional boundary layer is apt to form at the gas inlet to the foregoing turbine blades
3
.
Further, in the area of the foregoing tongue
45
, the difference in pressure above and below tongue
45
due to its thickness causes the generation of wake
50
, as shown in FIG.
13
(A). Then, as shown in FIG.
13
(A) for the conventional technology, since width between the walls downstream of the tongue
046
, being either the same as the width of the tongue edges
45
a
or gradually reduced from said tongue edge
45
a
, following the shape of scroll
4
, generates no action that would reduce the foregoing wake
50

Affiliated with

Also associated with

Rating

Structures of turbine scroll and blades does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Structures of turbine scroll and blades, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Structures of turbine scroll and blades will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3330485