Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Plural distributing means immediately upstream of runner
Reexamination Certificate
1999-12-30
2002-06-04
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Plural distributing means immediately upstream of runner
C415S211200, C415S228000, C416S16900R, C416S189000
Reexamination Certificate
active
06398492
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to axial flow fans and, more particularly, to an airflow guide stator vane for an axial flow fan capable of guiding air having dimensional velocity components along the axial direction, and a shrouded axial flow fan assembly having such airflow guide stator vanes.
2. Description of the Prior Art
As well known to those skilled in the art, an axial flow fan is a kind of fluid machinery and serves to blow air in the axial direction by the rotation of a plurality of radially arranged blades. Generally, the axial flow fan is used in conjunction with a shroud, the shroud surrounding the blades and guiding air toward the axial direction.
Such a shrouded axial flow fan assembly is used to ventilate a room and promote the heat radiation of an air-cooled heat exchanger, such as a radiator or a condenser of an automobile. The shrouded axial flow fan assembly may promote heat radiation by blowing air to or drawing air from the heat exchanger.
The shrouded axial flow fan may be classified into a pusher-type axial flow fan assembly and a puller-type axial flow fan assembly. The pusher-type axial flow fan assembly serves to blow air from a position in front of a heat exchanger to a position behind the heat exchanger. Since such a pusher-type axial flow fan assembly has a low blowing efficiency, it is used only when the space, formed behind the heat exchanger in an engine room, is significantly limited. The puller-type axial flow fan assembly serves to allow air to pass through the heat exchanger by drawing air from a position in front of the heat exchanger to a position behind the heat exchanger. Since such a puller-type axial flow fan assembly has a high blowing efficiency, it is used in most automobiles, recently.
Meanwhile, in the shrouded axial flow fan assembly, the shroud of the fan assembly may have a plurality of airflow guide stator vanes so as to improve a blowing efficiency. The airflow guide stator vanes are radially arranged around a center portion with the center of the center portion lying on the central axis of the fan assembly. The airflow guide stator vanes serve to improve static pressure by converting the kinetic energy of the air blown by the blades of the fan to the pressure energy of the air, thus improving the blowing efficiency of the fan.
FIG. 1
is a rear view showing a conventional puller-type shrouded axial flow fan assembly provided with airflow guide stator vanes.
As shown in
FIG. 1
, the axial flow fan assembly comprises an axial flow fan
10
and a shroud
30
.
The axial flow fan
10
consists of a central hub (not shown in the drawing) connected with the driving shaft of a motor (not shown) and a plurality of blades
12
extending radially outwardly from the hub. The axial flow fan
10
is mounted in the rear of a heat exchanger, and serves to draw air from the front of the heat exchanger, pass the air through the heat exchanger and discharge the air to the rear of the axial flow fan
10
. In the process of the movement of the air, the heat exchanger is deprived of heat by the drawn air and is cooled. The axial flow fan is generally made of synthetic resin and integrated with the blades
12
into a single body.
The shroud
30
surrounds the blades
12
and is fixed to the heat exchanger. The shroud
30
serves to guide air drawn by the axial flow fan to the rear and to support the axial flow fan
10
and a motor
10
. The shroud
10
consists of a rectangular housing
31
, a motor support
32
positioned in the center portion of a plane and a plurality of airflow guide stator vanes
33
arranged radially between the housing
31
and the motor sport
32
.
The housing
31
has an inlet opened toward the face of the heat exchanger and has a flaring airflow guide structure gradually diminished to its outlet. Its airflow guide structure allows the heat exchanger to be cooled sufficiently and blows air along the axial direction, thus improving the efficiency of the fan. The housing
31
is provided at its upper and lower portions with mounting brackets
34
that are used to mount the housing
31
to the heat exchanger by bolts.
The stator vanes
33
extend radially from the housing
31
to the motor support
32
and connect the motor support
32
to the housing
31
. Additionally, as shown in
FIG. 2
, each of the stator vanes is arcuated toward the direction of rotation and forms a guide surface
33
a
having a certain width, thus guiding air moved by the axial flow fan
10
toward the axial direction and improving the blowing efficiency of the fan.
The motor support
32
holds the axial flow fan
10
and a motor
20
for driving the axial flow fan
10
. The motor support
32
is circular band-shaped in accordance with the shape of the hub of the axial flow fan
10
and the shape of the motor
20
.
In the shrouded axial flow fan assembly, as shown in
FIG. 1
, the stator vanes
33
are extended straightly from the circumference of the motor support
32
to the housing
31
, and, as shown in
FIG. 2
, the airflow guide surface
33
a
of each of the stator vanes is arcuated so that one end side of the surface
33
a
forms an angle &thgr;t with the axial line A.L. The stator vanes
33
serve to increase the axis-directional velocity by converting the rotation-directional velocity component to the axis-directional velocity component, thus improving the blowing efficiency of the fan. That is, since airflow generated by the axial flow fan
10
has the rotation-directional velocity component U
th
as well as the axis-directional velocity component U
z
and the blowing efficiency of the fan is reduced when the rotation-directional velocity component U
th
is left alone, the axis-directional velocity is increased by converting the rotation-directional velocity component to the axis-directional velocity component, so that the blowing efficiency of the fan is improved.
The function of the airflow guide surface
33
a
of the airflow guide state vanes is described in more detail in the following.
In the airflow field inside of the housing
31
, an air particle is moved to the direction curved toward the direction of rotation and the radial direction. That is, as shown in
FIG. 2
, since the air particle, passing through the position spaced apart from the axial line of the axial flow fan by a distance r along the radial direction, has a rotation-directional velocity component U
th
generated by the rotation of the blades
12
of the axial flow fan
10
as well as an axis-directional velocity component U
z
, the air particle is moved toward the leading edge
33
b
of the stator vane
33
in the direction that is bent to the direction of rotation at &thgr;
T
with respect to the axial direction. Under the consideration of the actual airflow direction, the airflow guide surface
33
a
of each stator vane
33
is arcuated so that the leading edge side of the guide surface
33
a
forms an oblique angle &thgr;
t
(&thgr;
t
≦&thgr;
T
) with the axial line A.L. Therefore, the guide surface
33
a
reflects the air having oblique flow direction toward the axial direction and, thus, increases the axis-directional velocity. As a result, the blowing efficiency of the fan is improved due to the increase of the axis-directional velocity.
U.S. Pat. No. 4,548,548 discloses a fan and housing wherein the oblique angle of the airflow guide surface of each stator vane is defined with respect to the axial line so as to improve the blowing efficiency of the fan. The velocity vector A
D
of air at the position, which is spaced apart from the central line of rotation by a distance r in the field of airflow, has both an axis-directional velocity component A and a rotation-directional velocity component R. The velocity vector A
D
forms an oblique angle T of Tan
−1
(R/A) with the axial line. Each vane of the fan is positioned so that the width-directional tangent at the center of its width forms an angle T/2 with a line parallel to the airflow discharge direction with the airflow guide surface of
Cho Kyung Seok
Min Ok Ryul
Halla Climate Control Corp.
Look Edward K.
Nguyen Ninh
LandOfFree
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