U.S. patent application number 10/287209 was filed with the patent office on 2004-05-06 for two-piece molded fan.
Invention is credited to Malott, Theodore A..
Application Number | 20040083609 10/287209 |
Document ID | / |
Family ID | 32093600 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040083609 |
Kind Code |
A1 |
Malott, Theodore A. |
May 6, 2004 |
Two-piece molded fan
Abstract
A two-piece molded fan assembly is produced having overlapping
fan blades using an axial draw technique. The two halves are then
removed from the mold and coupled together to form the two-piece
fan. By molding the fan as two pieces, a fan blade can be produced
that wraps around the outside of the housing and overlaps with each
other in a quick and easy manner using a simple mold design. The
two pieces are formed such that the a portion of each overlapping
blade is formed on both halves of the assembly so that the die
casting tool can be removed along a central axis defining the fan
assembly without contacting the respective portion of the fan
blades, therein greatly simplifying the manufacturing
techniques.
Inventors: |
Malott, Theodore A.;
(Jackson, MI) |
Correspondence
Address: |
BorgWarner, Inc.
Powertrain Technical Center
3800 Automation Avenue
Suite 100
Auburn Hills
MI
48326
US
|
Family ID: |
32093600 |
Appl. No.: |
10/287209 |
Filed: |
November 4, 2002 |
Current U.S.
Class: |
29/889.3 |
Current CPC
Class: |
Y10T 29/49327 20150115;
F05D 2230/21 20130101; F04D 29/023 20130101; F04D 29/325 20130101;
F05D 2230/51 20130101 |
Class at
Publication: |
029/889.3 |
International
Class: |
B21D 053/78 |
Claims
What is claimed is:
1. A method for forming a fan assembly defined by and capable of
spinning about a central axis, said fan assembly having a plurality
of circumferentially displaced, radially disposed overlapping fan
blades coupled about a central hub, the method comprising
comprising: determining a relative positioning plane extending
through the plurality of overlapping fan blades and central hub of
the fan assembly, said relative positioning plane located such that
a front portion of said plurality of overlapping fan blades are
located on one side of the relative positioning plane a rear
portion of said plurality of overlapping fan blades are located on
the opposite side of said relative positioning plane; die casting
said front portion of the two piece fan assembly, said front
portion having said first portion of said plurality of overlapping
fan blades and a front hub portion and a substantially flat front
flat portion, said front flat portion defined by said relative
positioning plane; die casting a rear portion of the two piece fan
assembly, said rear portion having said second portion of said
plurality of overlapping fan blades and a rear hub portion and a
substantially flat rear flat portion, said rear flat portion
defined by said relative positioning plane; and coupling said front
portion to said rear portion to form the two-piece fan
assembly.
2. The method of claim 1, wherein die casting a front portion and
die casting a rear portion comprises: introducing a first quantity
of a molten material within said front portion of a die casting
tool; introducing a second quantity of said molten material within
said rear portion of said die casting tool; and cooling said first
quantity of cast molten material to form said front portion and
cooling said second quantity of cast molten material to form said
rear portion.
3. The method of claim 1, wherein said front hub portion has a
plurality of bolt holes formed therein and wherein said rear hub
portion has a second plurality of holes formed therein.
4. The method of claim 2, wherein coupling said front portion to
said rear portion comprises: providing a plurality of bolts, each
of said plurality of bolts having a head; forming a plurality of
front bolt holes on said front hub portion in a post-casting step;
forming a second plurality of rear bolt boles on said rear hub
portion in a post-casting step; coupling said front flat portion of
said front portion to said rear flat portion of said rear portion;
introducing one of said plurality of bolts through a corresponding
one of said plurality of front bolt holes and through a
corresponding one of said second plurality of rear bolt holes,
wherein at least one of said heads of said plurality of bolts is
closely coupled with said front hub portion; and securing each of
said plurality of bolts.
5. The method of claim 2, wherein coupling said front portion to
said rear portion comprises: providing a plurality of bolts, each
of said plurality of bolts having a head; forming a plurality of
front bolt holes on said front hub portion in a post-casting step;
forming a second plurality of rear bolt boles on said rear hub
portion in a post-casting step; coupling said front flat portion of
said front portion to said rear flat portion of said rear portion;
introducing one of said plurality of bolts through a corresponding
one of said second plurality of rear bolt holes and through a
corresponding one of said plurality of front bolt holes such that
at least one of said heads is closely coupled with said rear hub
portion; and securing each of said plurality of bolts.
6. The method of claim 4, wherein securing said plurality of bolts
comprises securing each of said plurality of bolts with a
corresponding nut, said corresponding nut closely coupled with said
rear hub portion.
7. The method of claim 5, wherein securing said plurality of bolts
comprises securing each of said plurality of bolts with a
corresponding nut, said corresponding nut closely coupled with said
front hub portion.
8. The method of claim 3, wherein coupling said front portion to
said rear portion comprises: providing a plurality of bolts, each
of said plurality of bolts having a head; coupling said front flat
portion of said front portion to said rear flat portion of said
rear portion; introducing one of said plurality of bolts through a
corresponding one of said plurality of front bolt holes and through
a corresponding one of said second plurality of rear bolt holes,
wherein at least one of said heads of said plurality of bolts is
closely coupled with said front hub portion; and securing each of
said plurality of bolts.
9. The method of claim 3, wherein coupling said front portion to
said rear portion comprises: providing a plurality of bolts, each
of said plurality of bolts having a head; coupling said front flat
portion of said front portion to said rear flat portion of said
rear portion; introducing one of said plurality of bolts through a
corresponding one of said second plurality of rear bolt holes and
through a corresponding one of said plurality of front bolt holes
such that at least one of said heads is closely coupled with said
rear hub portion; and securing each of said plurality of bolts.
10. The method of claim 8, wherein securing said plurality of bolts
comprises securing each of said plurality of bolts with a
corresponding nut, wherein said corresponding nut is closely
coupled with said rear hub portion.
11. The method of claim 9, wherein securing said plurality of bolts
comprises securing each of said plurality of bolts with a
corresponding nut, wherein said corresponding nut is closely
coupled with said front hub portion.
12. A method for die casting a two-piece fan assembly having a
plurality of circumferentially displaced, radially disposed
overlapping fan blades, said fan assembly capable of rotating about
a central axis, the method comprising: determining a relative
positioning plane extending through the plurality of overlapping
fan blades and central hub of the fan assembly, said relative
positioning plane located such that a front portion of said
plurality of overlapping fan blades are located on one side of the
relative positioning plane a rear portion of said plurality of
overlapping fan blades are located on the opposite side of said
relative positioning plane; die casting a front portion and a rear
portion of the two piece fan assembly within a die casting tool
having a front section and a rear section, wherein said front
portion having said first portion of said plurality of overlapping
fan blades and a substantially flat front flat portion, said front
flat portion defined by said relative positioning plane, wherein
said rear portion having said second portion of said plurality of
overlapping fan blades and a substantially flat rear flat portion,
said rear flat portion defined by said relative positioning plane;
uncoupling said front section of said die cast tool along said
central axis away from said relative positioning plane such that
said front section does not contact first portion of said plurality
of overlapping blades; and uncoupling said rear section of said die
cast tool along said central axis away from said relative
positioning plane such that said rear section does not contact
second portion of said plurality of overlapping blades.
13. The method of claim 12, wherein die casting a front portion and
die casting a rear portion comprises: introducing a first quantity
of a molten material within said front section; introducing a
second quantity of said molten material within said rear section;
and cooling said first quantity of cast molten material to form
said front portion and cooling said second quantity of cast molten
material to form said rear portion.
14. The method of claim 12, wherein said front hub portion has a
plurality of bolt holes formed therein and wherein said rear hub
portion has a second plurality of holes formed therein.
Description
TECHNICAL FIELD
[0001] The invention relates generally to fan drive systems and
more specifically, fan drive systems with two-piece molded
fans.
BACKGROUND ART
[0002] Cooling systems are used on vehicles today to provide
cooling to an engine during operation. A typical cooling system
comprises a water pump and a fan drive. Fan drives are typically
driven by the engine crankshaft at a fixed ratio to cool engine
coolant as it flows through a radiator. More specifically, a fan
that is rigidly mounted to the fan drive generates the airflow as a
function of engine crankshaft rotational speed for cooling the
radiator.
[0003] One important consideration with fans is the ease of
manufacture. In automotive applications, molded plastic parts with
a minimum number of parts and assembly steps are generally most
cost effective. As will be recognized by those of skill in the
molding art, one of the most cost effective ways to mold plastic is
by the so called axial draw technique or by pass molding technique,
which uses only two molds that part along a natural axis of the
component. The ultimate in fan simplicity using this technique is a
one-piece fan design. In order to be moldable by that technique,
the part must have a certain structural relationship relative to
its central axis, such as the central axis of the fan. All "upper"
and "lower" surfaces of the part must be divisible in such a way
that they have no radial overlap with one another. If so designed,
all part surfaces may be divided up so that some can be molded by
one die, and the rest by the other die, and the pair of die (or
molds) can be pushed together and pulled apart freely along the
same central axis. This represents the absolute minimum in terms of
molds used (two) to produce the parts, and the number of pieces
(one) in the part produced.
[0004] As will be recognized by those of skill in the art, the
number of fan blade configurations that can be made using a
one-piece mold is thus limited to configurations that can be pulled
apart freely along the same central axis. For example, overlapping
blade fans cannot currently be made using the axial draw technique
because the blade overlap would prevent part removal if the whole
fan was cast as one piece.
[0005] It is thus highly desirable to introduce a overlapping blade
fan using the axial draw technique.
SUMMARY OF THE INVENTION
[0006] The above and other objects of the invention are met by the
present invention. In the present invention, a two-piece fan
integrated with the fan drive is produced having overlapping fan
blades using an axial draw technique. The two halves are then
removed from the mold and bolted together to form the two-piece
fan.
[0007] By molding the fan as two pieces, a fan blade can be
produced that wraps around the outside of the housing and overlaps
with each other. The molding can be done within one die casting
tool having a front and rear section or can be done with two
separate die casting tools.
[0008] Other features, benefits and advantages of the present
invention will become apparent from the following description of
the invention, when viewed in accordance with the attached drawings
and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a two-piece fan assembly
according to one preferred embodiment of the present invention;
[0010] FIG. 2 is an exploded view of the two-piece fan
assembly;
[0011] FIG. 3 is a front view of FIG. 1; and
[0012] FIG. 4 is a side view of FIG. 1 indicating mold release
directions.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0013] Referring now to the drawings, which are not intended to
limit the invention, FIGS. 1-4 indicates a two-piece fan assembly
10 according to a preferred embodiment of the present invention.
The two-piece fan assembly 10 is generally defined about a central
axis A, and also spins about the same axis in operation. The
two-piece fan assembly 10 is preferably formed of die cast aluminum
or molded plastic, although other materials may be used as those of
skill in the art recognize.
[0014] The structural foundation of the fan assembly 10 is the
central hub 12, which is basically an annular disk that extends
radially outward from a center bore 14. The center bore 14 is the
attachment point of a motor shaft (not shown) that spins the fan
assembly 10 about central axis A. The motor shaft, and associated
housing, have a conventional arrangement well known to those of
skill in the art and will not be discussed further in this
application.
[0015] Disposed about the central hub 12 are a plurality of
circumferentially displaced, radially disposed fan blades 16 having
a radially inner portion 32 of their bases integrally molded with,
and supported by, the central hub 12. Also note that each fan blade
16 has a part of the front side portion 34 blocked by the next
adjacent front side portion 34 when a person views the fan blade 16
from the side as in FIG. 3 (i.e. there is at least a partial
overlap of the blades 16 as viewed from the front or back). This
overlapping blade 16 structure, as one of skill in the art
appreciates, enables the fan assembly 10 to provide increased air
flow as compared with fan assemblies having non-overlapping blade
structures.
[0016] The fan assembly 10 consists of a front portion 20 (left
half of FIG. 4) and a rear portion 22 (right half of FIG. 4)
fastened together through a coupling device known to those of skill
in the art. Both the front portion 20 and rear portion 52 have a
substantially flat region 50a, 50b that is defined by and
corresponding to the relative positioning plane 52. As such, the
central hub 12 consists of a front hub portion 12a and a rear hub
portion 12b. Similarly, the fan blades 16 consist of a front fan
blade portion 16a and a rear fan blade portion 16b. As best seen in
FIG. 4, each front fan blade portion 16a is coupled to a rear fan
blade portion 16b such that they form a relatively smooth coupling
along and between each radially outward portion 30, radially inward
portion 32, front side portion 34 and rear side portion 36 when the
front portion 20 is coupled to the rear portion 22.
[0017] In the preferred embodiments as shown in FIGS. 1-4, the
front portion 20 and rear portion 22 are formed with a plurality of
bolt holes 25a, 25b. Of course, the boltholes 25a, 25b could also
be formed in a post-casting step using a drill or similar
equipment.
[0018] As best shown in FIG. 4, to couple the front portion 20 to
the rear portion 22, the flat portions 50a, 50b are first aligned
along either side of the relative positioning plane 52. A bolt 24
is then inserted through a corresponding bolthole 25a and 25b to
secure the front portion 20 to the rear portion 22. The bolt 24 may
be secured within the respective pair of boltholes 25a, 25b by a
corresponding nut (not shown) or other methods well known in the
art. While the embodiments shown in FIGS. 1-4 indicate 12 bolts 24
and 12 corresponding bolt holes 25a, 25b circumferentially placed
around the hub portions 12a, 12b, the number and location of the
bolts 24 and bolt holes 25a, 25b may vary as one of skill in the
art would appreciate. Further, while the bolts 24 are shown with
their head portions 24a, closely coupled with the front portion 20,
one of skill would recognize that it is equally plausible that the
bolt 24 is secured with the head portion 24a closely coupled with
the rear portion 22 to secure the front portion 20 to the rear
portion 22.
[0019] Referring now to FIG. 4, the fan assembly 10 is formed by
die casting the front portion 20 and rear portion 22 as two
separate pieces within a corresponding die casting tool separated
along a relative positioning plane 52. After introduction of the
molten material and die casting has occurred within the die cast
tool (not shown) by conventional techniques, the die cast tool
separates, as indicated by the arrows, along the axis A away from
the relative positioning plane 52, thereby allowing the two
portions 20, 22 to be removed from the tooling. As one of skill
would recognize, the overlapping structure of the fan blades 16
would prevent part removal if the fan assembly 10 were cast as a
single part using an axial draw technique. Here, the front section
of the die cast tool separates from the front portion 20 along the
axis A away from the relative positioning plane 52 such that the
front section of the tool does not contact the front section of the
overlapping blades 16a. At the same time, the rear section of the
die cast tool separates from the rear portion 22 along axis A away
from the relative positioning plane 52 such that the rear section
does not contact the rear section of the overlapping blades
16b.
[0020] Of course, as is appreciated by one of skill in the art, the
front portion 20 and rear portion 22 could be formed within two
separate die casting tools using the axial draw technique.
[0021] Thus, the present invention presents a simple, easy and
efficient procedure for casting a fan assembly 10 having an
overlapping fan blade 16 structure using an axial draw technique.
Importantly, the technique presented in the present invention can
be applied to a potentially infinite variety of overlapping fan
blade designs. All that is required to incorporate this technique
is to determine a relative positioning plane 52 within the fan
assembly 10 cutting through the fan blades 16 and hub 12 such that
the die cast tool can be pulled apart along the axis A of the fan
assembly 10 after the portions 20, 22 are die cast.
[0022] While the invention has been described in connection with
one embodiment, it will be understood that the invention is not
limited to that embodiment. On the contrary, the invention covers
all alternatives, modifications, and equivalents as may be included
within the spirit and scope of the appended claims.
* * * * *