U.S. patent application number 14/297712 was filed with the patent office on 2015-01-22 for serial fan device.
The applicant listed for this patent is Sunonwealth Electric Machine Industry Co., Ltd.. Invention is credited to Feng-Ming Chang, Ming-Tsung Li.
Application Number | 20150023786 14/297712 |
Document ID | / |
Family ID | 50133017 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150023786 |
Kind Code |
A1 |
Li; Ming-Tsung ; et
al. |
January 22, 2015 |
Serial Fan Device
Abstract
a serial fan device including two fans linked serially is
provided. Each of the two fans has a housing, a driving member and
a fan wheel, the housing has an outer frame and a base, the outer
frame has two openings and a guiding channel linking the two
openings, the driving member is disposed on the base, and the fan
wheel is rotatably coupled with the driving member. At least one of
the two fans has a positioning rim on the outer frame for the base
to couple therewith, and a radial buffer gap is formed between an
outer periphery of the base and an inner periphery of the
positioning rim. Accordingly, the radial buffer gap can largely
reduce the vibration transmitted from the base to the outer
frame.
Inventors: |
Li; Ming-Tsung; (Kaohsiung,
TW) ; Chang; Feng-Ming; (Kaohsiung, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sunonwealth Electric Machine Industry Co., Ltd. |
Kaohsiung City |
|
TW |
|
|
Family ID: |
50133017 |
Appl. No.: |
14/297712 |
Filed: |
June 6, 2014 |
Current U.S.
Class: |
415/199.4 |
Current CPC
Class: |
F04D 29/646 20130101;
F04D 19/007 20130101; F04D 29/668 20130101 |
Class at
Publication: |
415/199.4 |
International
Class: |
F04D 19/00 20060101
F04D019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2013 |
TW |
102125613 |
Claims
1. A serial fan device comprising: two fans linked serially,
wherein each of the two fans has a housing, a driving member and a
fan wheel, wherein the housing has an outer frame and a base,
wherein the outer frame has two openings and a guiding channel
linking the two openings, wherein the driving member is disposed on
the base, and wherein the fan wheel is rotatably coupled with the
driving member, wherein at least one of the two fans has a
positioning rim on the outer frame for the base to couple
therewith, wherein the positioning rim of the outer frame has a
minimal inner diameter, and wherein the base has a maximal outer
diameter smaller than or equal to the minimal inner diameter.
2. The serial fan device as claimed in claim 1, wherein a radial
buffer gap is formed between an outer periphery of the base and an
inner periphery of the positioning rim.
3. The serial fan device as claimed in claim 2, wherein the
positioning rim has an axial shoulder abutting against the
base.
4. The serial fan device as claimed in claim 3, wherein the outer
frame of the fan having the radial buffer gap is a hollow body,
wherein the positioning rim is formed on an end section of the
guiding channel defining one of the two openings, wherein the base
of the housing includes a seat, a plurality of connecters and a
coupling member, wherein the plurality of connecters connects with
the seat by one end and the coupling member by another end, wherein
the base couples with the positioning rim by the coupling member,
wherein the coupling member abuts against the axial shoulder, and
wherein an outer periphery of the coupling member is spaced from
the inner periphery of the positioning rim by the radial buffer
gap.
5. The serial fan device as claimed in claim 3, wherein the outer
frame of the fan having the radial buffer gap has a hollow body, a
plurality of connecters and a coupling member, wherein the
plurality of connecters connects with an inner periphery of the
hollow body by one end and the coupling member by another end,
wherein the base is a seat, wherein the positioning rim is formed
on an end of the coupling member, wherein the axial shoulder is
arranged on the inner periphery of the positioning rim, wherein the
base couples with the positioning rim and abuts against the axial
shoulder, and wherein the outer periphery of the base is spaced
from the inner periphery of the positioning rim by the radial
buffer gap.
6. The serial fan device as claimed in claim 3, wherein the outer
frame of the fan having the radial buffer gap is a hollow body,
wherein the positioning rim is formed on an end section of the
guiding channel defining one of the two openings, wherein the base
of the housing includes a seat and a plurality of connecters,
wherein the plurality of connecters connects with the seat by one
end and the positioning rim by another end, wherein each end of the
connecters connecting with the positioning rim has an axial edge
abutting against the axial shoulder and a radial edge spaced from
the inner periphery of the positioning rim by the radial buffer
gap.
7. The serial fan device as claimed in claim 3, wherein the two
fans are a first fan and a second fan, wherein the base of the
first fan is spaced from the inner periphery of the positioning rim
of the first fan by the radial buffer gap, and wherein the base of
the second fan is spaced from the inner periphery of the
positioning rim of the second fan by the radial buffer gap.
8. The serial fan device as claimed in claim 7, wherein the bases
of the first and second fans are axially clamped by and between the
axial shoulders of the first and second fans.
9. The serial fan device n as claimed in claim 7, wherein the first
and second fans are coupled with each other by a fixing
assembly.
10. The serial fan device as claimed in claim 9, wherein the fixing
assembly includes a first hook member arranged on the first fan and
a second hook member arranged on the second fan, and wherein the
first and second hook members are capable of detachably engaging
with each other.
11. The serial fan device as claimed in claim 1, further comprising
a damping member inserted between the two fans.
12. The serial fan device as claimed in claim 7, further comprising
a damping member inserted between the first and second fans.
13. The serial fan device as claimed in claim 12, wherein each of
the bases of the first and second fans has a recess for the damping
member to be received in a space jointly formed by the recesses and
between the bases of the first fan and the second fan.
14. The serial fan device as claimed in claim 12, wherein the
damping member includes an annular flange on a periphery thereof,
and the annular flange is clamped by lateral walls of the seats of
the two fans.
15. The serial fan device as claimed in claim 1, wherein an edge of
one of the two openings has an engaging notch, the said opening
having the engaging notch has the positioning rim for the base to
couple therewith, and the base has an engaging protrusion
corresponding to and able to insert into the engaging notch.
16. The serial fan device as claimed in claim 15, wherein lateral
walls of the engaging notch form two opposite limiting flanges
respectively, wherein two guiding flanges are formed on two
opposite lateral walls of the engaging protrusion, and the engaging
protrusion rests inside the engaging notch, and with the two
limiting flanges engaging with the two guiding flanges
respectively.
17. The serial fan device as claimed in claim 1, wherein the
positioning rim of the outer frame has a connecting groove, and the
base has an elastic hook corresponding to and able to insert into
the connecting groove.
18. The serial fan device as claimed in claim 4, wherein the
coupling member is a ring.
19. The serial fan device as claimed in claim 5, wherein the
coupling member is a ring.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to a serial fan
device and, more particularly, it relates to a serial fan device
formed by a plurality of fans serially combined.
[0003] 2. Description of the Related Art
[0004] A conventional serial fan device is usually formed by a
plurality of series-connected fans so as to provide improved wind
volume and enhanced cooling effect relative to a single fan.
Unfortunately, since there is vibration in the operation of a fan
usually, the degree of the vibration of a serial fan device formed
by plural fans can be much more serious than that of a single fan.
When the serial fan device is applied in an electronic system, such
as a computer server, this kind of serious vibration not only
induces noises, but also lowers the operational stability of the
electronic system as well as accelerates the deterioration of the
circuit joints inside the electronic system, and thus shortens the
lifetime of this electronic system.
[0005] Therefore, referring to FIG. 1, an invention entitled as
"Vibration Damping Structure of Serial Fan Device," with a Taiwan
patent number of 1324504, is provided to disclose a conventional
serial fan device 9 capable of vibration damping. This serial fan
device 9 includes two frames 91, 92 connecting with each other in
series, with each of the frames 91, 92 having a base 911 or 921
adapted to couple with an impeller. Specifically, there is a
damping member 93 inserted in a space between opposite faces of the
series-connected frames 91, 92. Accordingly, since the damping
member 93 is formed by flexible material for vibration damping and
buffering, the damping member 93 is able to damp the vibration from
the impellers inside the frames 91, 92 to restrain resonance and
noise of the frames 91, 92 when the impellers turn.
[0006] However, although the damping member 93 can restrain
resonance and noise of the frames 91, 92, the operational vibration
can still transmit via routes from the bases 911, 921 to the other
parts of the frames 91, 92 since the impellers are rotatably
mounted on the bases 911, 921. As a result, the damping performance
provided by the damping member 93 against the resonance and noise
is quite limited, and thus the remaining vibration can still lower
the operational stability of an electronic system, induce noises,
and shorten the lifetime of this electronic system when the serial
fan device 9 is installed in this electronic system and operated.
Moreover, the said remaining vibration may also cause a fault or
failure in reading operation of a hard disk in the electronic
system.
[0007] As a result, it is necessary to improve the conventional
serial fan device.
SUMMARY OF THE INVENTION
[0008] It is therefore the objective of this invention to provide a
serial fan device to efficiently break a route for vibration
transmission, to largely damp the vibration caused by operation of
a fan wheel, and to maintain operational stability and lower noise
of an electronic system.
[0009] One embodiment of the invention discloses a serial fan
device, which includes two fans linked serially. Each of the two
fans has a housing, a driving member and a fan wheel, the housing
has an outer frame and a base, the outer frame has two openings and
a guiding channel linking the two openings, the driving member is
disposed on the base, and the fan wheel is rotatably coupled with
the driving member. At least one of the two fans has a positioning
rim on the outer frame for the base to couple therewith, the
positioning rim of the outer frame has a minimal inner diameter,
and the base has a maximal outer diameter smaller than or equal to
the minimal inner diameter. Preferably, the positioning rim has an
axial shoulder abutting against the base. More preferably, a radial
buffer gap is formed between an outer periphery of the base and an
inner periphery of the positioning rim.
[0010] In a preferred form shown, the outer frame of the fan having
the radial buffer gap is a hollow body, the positioning rim is
formed on an end section of the guiding channel defining one of the
two openings, the base of the housing includes a seat, a plurality
of connecters and a coupling member, the plurality of connecters
connects with the seat by one end and the coupling member by
another end, the base couples with the positioning rim by the
coupling member, the coupling member abuts against the axial
shoulder, and an outer periphery of the coupling member is spaced
from the inner periphery of the positioning rim by the radial
buffer gap.
[0011] In a preferred form shown, the outer frame of the fan having
the radial buffer gap has a hollow body, a plurality of connecters
and a coupling member, the plurality of connecters connects with an
inner periphery of the hollow body by one end and the coupling
member by another end, the base is a seat, the positioning rim is
formed on an end of the coupling member, the axial shoulder is
arranged on the inner periphery of the positioning rim, the base
couples with the positioning rim and abuts against the axial
shoulder, and the outer periphery of the base is spaced from the
inner periphery of the positioning rim by the radial buffer
gap.
[0012] In a preferred form shown, the outer frame of the fan having
the radial buffer gap is a hollow body, the positioning rim is
formed on an end section of the guiding channel defining one of the
two openings, the base of the housing includes a seat and a
plurality of connecters, the plurality of connecters connects with
the seat by one end and the positioning rim by another end, each
end of the connecters connecting with the positioning rim has an
axial edge abutting against the axial shoulder and an radial edge
spaced from the inner periphery of the positioning rim by the
radial buffer gap.
[0013] In a preferred form shown, the two fans are a first fan and
a second fan, the base of the first fan is spaced from the inner
periphery of the positioning rim of the first fan by the radial
buffer gap, and the base of the second fan is spaced from the inner
periphery of the positioning rim of the second fan by the radial
buffer gap.
[0014] In the preferred form shown, the bases of the first and
second fans are axially clamped by and between the axial shoulders
of the first and second fans.
[0015] In the preferred form shown, the first and second fans are
coupled with each other by a fixing assembly. Preferably, the
fixing assembly includes a first hook member arranged on the first
fan and a second hook member arranged on the second fan, and the
first and second hook members are capable of detachably engaging
with each other.
[0016] In a preferred form shown, a damping member is inserted
between the two fans.
[0017] In the preferred form shown, each of the bases of the first
and second fans has a recess for the damping member to be received
in a space jointly formed by the recesses and between the bases of
the first fan and the second fan.
[0018] In the preferred form shown, the damping member includes an
annular flange on a periphery thereof, and the annular flange is
clamped by lateral walls of the seats of the two fans.
[0019] In a preferred form shown, an edge of one of the two
openings has an engaging notch, the said opening having the
engaging notch has the positioning rim for the base to couple
therewith, and the base has an engaging protrusion corresponding to
and able to insert into the engaging notch.
[0020] In the preferred form shown, lateral walls of the engaging
notch form two opposite limiting flanges respectively, two guiding
flanges are formed on two opposite lateral walls of the engaging
protrusion, and the engaging protrusion rests inside the engaging
notch with the two limiting flanges engaging with the two guiding
flanges respectively.
[0021] In a preferred form shown, the positioning rim of the outer
frame has a connecting groove and the base has an elastic hook
corresponding to and able to insert into the connecting groove.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will become more fully understood from
the detailed description given hereinafter and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0023] FIG. 1 is an exploded and perspective view of a conventional
serial fan device.
[0024] FIG. 2 is an exploded and perspective view of a serial fan
device according to a first embodiment of the invention.
[0025] FIG. 3 is a cross-sectional view of the serial fan device
according to the first embodiment.
[0026] FIG. 4 is a partially enlarged cross-sectional view of the
serial fan device according to the first embodiment.
[0027] FIG. 5 is an exploded and perspective view of the serial fan
device according to the first embodiment with engaging notches and
engaging protrusions.
[0028] FIG. 6 is a partially enlarged and perspective view of one
pair of the engaging notches and engaging protrusions of the serial
fan device according to the first embodiment.
[0029] FIG. 7 is a partially enlarged and perspective view of one
pair of the engaging notches and engaging protrusions of the serial
fan device according to the first embodiment with limiting flanges
and guiding flanges.
[0030] FIG. 8 is a cross-sectional view of the serial fan device
according to the first embodiment with a space formed by recesses
for receiving a damping member.
[0031] FIG. 9 is a cross-sectional view of the serial fan device
according to the first embodiment with two separate recesses and a
damping member clamped by bottom walls of the recesses.
[0032] FIG. 10 is a cross-sectional view of the serial fan device
according to the first embodiment with a damping member having an
annular flange on a periphery thereof.
[0033] FIG. 11 is a cross-sectional view of a serial fan device
according to a second embodiment of the invention.
[0034] FIG. 12 is a partially enlarged and cross-sectional view of
the serial fan device according to the second embodiment.
[0035] FIG. 13 is an exploded and perspective view of the serial
fan device according to the second embodiment with connecting
grooves and elastic hooks.
[0036] FIG. 14 is a detailed and perspective view of one pair of
the connecting grooves and elastic hooks of the serial fan device
according to the second embodiment.
[0037] FIG. 15 is a detailed and cross-sectional view of one pair
of the connecting grooves and elastic hooks of the serial fan
device according to the second embodiment.
[0038] FIG. 16 is an exploded and perspective view of a serial fan
device according to a third embodiment of the invention.
[0039] FIG. 17 is a cross-sectional view of the serial fan device
according to the third embodiment.
[0040] FIG. 18 is a detailed cross-sectional view of the serial fan
device according to the third embodiment.
[0041] FIG. 19 is a cross-sectional view of the serial fan device
according to the first embodiment wherein only one of two fans has
a radial buffer gap.
[0042] In the various figures of the drawings, the same numerals
designate the same or similar parts. Furthermore, when the term
"first," "second," "third," "bottom," "inner," "outer" and similar
terms are used hereinafter, it should be understood that these
terms refer only to the structure shown in the drawings as it would
appear to a person viewing the drawings, and are utilized only to
facilitate describing the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Referring to FIGS. 2 and 3, a first embodiment of a serial
fan device of the present invention is shown, which includes a
first fan F1 and a second fan F2, wherein axial directions of the
first and second fans F1, F2 are in alignment and these two fans
F1, F2 are linked serially.
[0044] The first fan F1 includes a housing 1, a driving member 2
and a fan wheel 3. The housing 1 includes an outer frame 11 and a
base 12. The outer frame 11 has two openings 111, 112 and a guiding
channel 113 linking these two openings 111, 112, wherein any one of
the openings 111, 112 serves as an air inlet and the other one
serves as an air outlet, such as the opening 111 serves as the air
inlet while the opening 112 serves as the air outlet, and vice
versa. The outer frame 11 has a positioning rim 114 with an axial
shoulder 115 forming a supporting surface facing the opening 112.
Therefore, the base 12 can be inserted in and surrounded by the
positioning rim 114 and abut against the supporting surface of the
axial shoulder 115.
[0045] Please refer to FIG. 3 and further to FIG. 4. The
positioning rim 114 of the outer frame 11 has an inner periphery
with a minimal inner diameter "d1." The base 12 has an outer
periphery with a maximal outer diameter "d2" not larger than,
namely being smaller than or equal to, the minimal inner diameter
"d1," so as to form a radial buffer gap "D" between the outer
periphery of the base 12 and the inner periphery of the positioning
rim 114. The radial buffer gap "D" can totally or partially
separate the said inner and outer peripheries. Moreover, the
driving member 2 is disposed on the base 12 of the housing 1, and
the fan wheel 3 is rotatably coupled with the driving member 2.
With the rotation of the fan wheel 3, an air current can be induced
and pass through the guiding channel 113 by entering via one of the
openings 111, 112 and existing via the other one of them, such as
sequentially flowing through the opening 111, guiding channel 113
and opening 112. The driving member 2 may include elements for
turning the fan wheel 3, such as silicon steel plates, stator coils
and a control circuit board.
[0046] In this first embodiment, the outer frame 11 of the housing
1 is a hollow body 11a, the positioning rim 114 is formed on an end
section of the guiding channel 113 defining the opening 112, and
the axial shoulder 115 is arranged on the inner periphery of the
positioning rim 114. The base 12 of the housing 1 includes a seat
12a, a plurality of connecters 12b and a coupling member 12c. The
plurality of connecters 12b locates between the seat 12a and the
coupling member 12c while connecting with the seat 12a by one end
and the coupling member 12c by another end. Each of the connecters
12b is in the shape of a rib and, preferably, is a blade-shaped
rib. The coupling member 12c is in the shape of a ring around the
seat 12a and the plural connecters 12b. Thereby, as shown in FIGS.
3 and 4, the base 12 couples with the positioning rim 114 by the
coupling member 12c, with the coupling member 12c abutting against
the supporting surface of the axial shoulder 115, and with an outer
periphery of the coupling member 12c being spaced from the inner
periphery of the positioning rim 114 by the radial buffer gap
"D."
[0047] Referring to FIGS. 5 and 6 now, it is preferable that an
edge of the opening 112 of the outer frame 11 has at least one
engaging notch 116 and the base 12 has at least one engaging
protrusion 122 corresponding to and able to insert into the said at
least one engaging notch 116. Therefore, with the engagement of the
engaging notch 116 and the protrusion 122, the outer frame 11 can
be easily coupled with the base 12 in a predetermined orientation,
and any undesirable relative rotation between the outer frame 11
and base 12 is also avoided as well as a preferred performance of
engagement therebetween is provided. Besides, as shown by FIG. 7,
lateral walls of the engaging notch 116 preferably form two
opposite limiting flanges 117 while two guiding flanges 122a are
formed on two opposite lateral walls of the engaging protrusion
122. As a result, the guiding flanges 122a guide the engaging
protrusion 122 to pass through an opening between the limiting
flanges 117 and to rest inside the engaging notch 116 while the
engaging portion 122 is pressed toward the engaging notch 116 by an
external force. Finally, the two limiting flanges 117 engage with
the two guiding flanges 122a respectively to prevent the base 12
from an axial reverse movement leading to disengagement of the base
12 relative to the outer frame 11.
[0048] Regarding to the second fan F2, the structure of the second
fan F2 is basically similar to that of the first fan F1; namely,
the second fan F2 also includes a housing 1, a driving member 2 and
a fan wheel 3 identical to those described above. When the first
and second fans F1, F2 link with each other serially, the bases 12
of these two fans F1, F2 abut against each other and are axially
clamped by and between the axial shoulders 115 of these two fans
F1, F2 while the radial buffer gaps "D" are still remained.
Furthermore, in order to link the first and second fans F1, F2 and
to keep their relative positions, it is preferred to further
include a fixing assembly 4 for firmly coupling these two fans F1,
F2 by hooking, screwing or welding. In this embodiment, the fixing
assembly 4 includes a first hook member 41 arranged on the first
fan F1 and a second hook member 42 arranged on the second fan F2,
and the first and second hook members 41, 42 are capable of
detachably engaging with each other, so that the fixing assembly 4
can prevent any one of the fans F1, F2 from disengagement and
rotation relative to the other one thereof.
[0049] Referring to FIG. 8, it is preferable that a damping member
5 is inserted between the first and second fans F1, F2. The damping
member 5 can be formed by a material able to provide functions of
damping and buffering, such as rubber, foam, sponge, polyurethane,
etc. As shown in FIG. 8, each of the bases 12 of the first and
second fans F1, F2 has a recess 121 and the recess 121 of the first
fan F1 communicates with the recess 121 of the second fan F2 for
the damping member 5 to be received in the space jointly formed by
the two recesses 121 and sandwiched between the bases 12 of the
first fan F1 and the second fan F2. Alternatively, as shown in FIG.
9, the recesses 121 of the first and second fans F1, F2 can be
separated while the damping member 5 is clamped by bottom walls of
the recesses 121. With this damping member 5, the vibration caused
by rotation of the fan wheels 3 can be damped by the damping member
5 when the fan wheels 3 of the first and second fans F1, F2 are
operated. Moreover, referring to FIG. 10, the damping member 5
received in the recesses 121 shown in the FIG. 8 can be modified to
further include an annular flange 51 on a periphery of the damping
member 5, so that the damping member 5 can totally separate the
seats 12a of the first and second fans F1, F2 and firmly engaged
therebetween, with the annular flange 51 being clamped between
lateral walls of the seats 12a of the two fans F1, F2.
[0050] Referring to FIGS. 11 and 12, a second embodiment of the
serial fan device of the present invention is shown, which also
includes a first fan F1 and a second fan F2. The first and second
fans F1, F2 of this embodiment are similar to those of the first
embodiment except for the following structural difference. In this
second embodiment, the outer frame 11 of the housing 1 includes a
hollow body 11a, a plurality of connecters 11b and a coupling
member 11c. The plurality of connecters 11b locates between the
hollow body 11a and the coupling member 11c while connecting with
an inner periphery of the hollow body 11a by one end and the
coupling member 11c by another end. Each of the connecters 11b is
in the shape of a rib and, preferably, is a blade-shaped rib. The
coupling member 11c is in the shape of a ring received in the
hollow body 11a. The base 12 is a seat 12a, the positioning rim 114
is formed on an end of the coupling member 11c, and an axial
shoulder 115 is arranged on the inner periphery of the positioning
rim 114. Thereby, the base 12, the seat 12a namely, couples with
the positioning rim 114 and abuts against a supporting surface of
the axial shoulder 115, and an outer periphery of the base 12 is
spaced from the inner periphery of the positioning rim 114 by the
radial buffer gap "D."
[0051] Additionally, as shown in FIGS. 13-15, it is preferable that
the positioning rim 114 of the outer frame 11 has at least one
connecting groove 118 and the base 12 has at least one elastic hook
123 corresponding to and able to insert into the said at least one
connecting groove 118. Therefore, the base 12 with the elastic hook
123 can be easily coupled with the outer frame 11 with the
connecting groove 118, and thus functions of convenient assembly
and anti-disengagement are accordingly provided.
[0052] Referring to FIGS. 16-18, a third embodiment of the serial
fan device of the present invention is shown, which also includes a
first fan F1 and a second fan F2. The first and second fans F1, F2
of this embodiment are similar to those of the first embodiment
except that the coupling member 12c of the base 12 in the first
embodiment is omitted. As a result, the plurality of connecters 12b
connects with the seat 12a by one end and the positioning rim 114
by another end. As shown by FIG. 18, each end of the connecters 12b
connecting with the positioning rim 114 has an axial edge 121b
abutting against the axial shoulder 115 and a radial edge 122b
spaced from the inner periphery of the positioning rim 114 by the
radial buffer gap "D."
[0053] Additionally, although all the embodiments show that, for
each of the first and second fans F1, F2, the maximal outer
diameter "d2" of the base 12 is not larger than the minimal inner
diameter "d1" of the positioning rim 114, the above described
relationship of the maximal outer diameter "d2" and the minimal
inner diameter "d1" can only be applied to one of the two fans F1,
F2 as shown in FIG. 19.
[0054] In sum, with the above illustrated embodiments of the serial
fan device, since the positions of the bases 12 of the first and
second fans F1, F2 are axially fixed and at least one of the fans
F1, F2 has its base 12 with a maximal outer diameter "d2" not
larger than a minimal inner diameter "d1" of its positioning rim
114, the vibration caused by the operation of the fan wheel 3 and
transmitted to the base 12 through the driving member 2 can be
efficiently isolated from the outer frame 11 of the housing 1 by
the radial buffer gap "D." Consequently, the operational stability
of an electronic system with this serial fan device can be
maintained as well as a low noise performance is acquired. Besides,
even if the bases 12 are axially clamped and fixed, an efficient
damping and buffering effect is still achievable for noise-reducing
and lifetime prolonging as long as the damping member 5 is inserted
between the first and second fans F1, F2 to damp the vibration
induced by the rotation of the fan wheel 3.
[0055] Although the invention has been described in detail with
reference to its presently preferable embodiments, it will be
understood by one of ordinary skill in the art that various
modifications can be made without departing from the spirit and the
scope of the invention, as set forth in the appended claims.
* * * * *