U.S. patent application number 11/898090 was filed with the patent office on 2009-03-12 for heat sink for an electrical device and method of manufacturing the same.
Invention is credited to Yu-Jen Lai, Song-Kai Su.
Application Number | 20090065174 11/898090 |
Document ID | / |
Family ID | 40430591 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090065174 |
Kind Code |
A1 |
Lai; Yu-Jen ; et
al. |
March 12, 2009 |
Heat sink for an electrical device and method of manufacturing the
same
Abstract
A heat sink for an electrical device has a frame and at least
one fin. The frame has an inner chamber. The fin is mounted in the
inner chamber of the frame to separate the inner chamber of the
frame into at least two channels. Therefore, heat generated from
any electrical element connected to or mounted on the heat sink
will transfer evenly to the heat sink. The heat sink not only
dissipates heat evenly, but also provides multiple channels to
dissipate heat by convection. Because the heat sink only has one
frame, assembly of an electrical device is easy and quick.
Inventors: |
Lai; Yu-Jen; (Taipei,
TW) ; Su; Song-Kai; (Taipei, TW) |
Correspondence
Address: |
Hershkovitz & Associates, LLC
2845 Duke Street
Alexandria
VA
22314
US
|
Family ID: |
40430591 |
Appl. No.: |
11/898090 |
Filed: |
September 10, 2007 |
Current U.S.
Class: |
165/80.3 |
Current CPC
Class: |
H01L 23/467 20130101;
H01L 2924/0002 20130101; H01L 2924/0002 20130101; H01L 23/367
20130101; H01L 2924/00 20130101 |
Class at
Publication: |
165/80.3 |
International
Class: |
F28F 7/00 20060101
F28F007/00 |
Claims
1. A heat sink for an electrical device comprising a frame, having
an inner chamber; two mounting sides being defined as opposite to
each other and being adapted to allow generating heat elements of
the electrical device to be mounted on the mounting sides; and two
non-mounting sides being defined as opposite to each other and at
least one of the non-mounting sides allowing the heat sink to be
fastened to the electrical device; at least one fin mounted in the
inner chamber of the frame to separate the inner chamber of the
frame into at least two channels and each fin having two edges
being connected respectively to the two mounting sides of the
frame.
2. The heat sink for an electrical device as claimed in claim 1,
wherein each fin is rectangular.
3. The heat sink for an electrical device as claimed in claim 2,
wherein the frame is made of extruded aluminum; and the at least
one fin is aluminum extruded from the frame.
4. The heat sink for an electrical device as claimed in claim 1,
wherein said electrical device is an UPS.
5. A method of manufacturing a heat sink for an electrical device
comprising steps of: a) making a frame which has an inner chamber;
two mounting sides being defined as opposite to each other and
being used for mounting generating heat electrical elements; and
two non-mounting sides being defined as opposite to each other and
at least one of them being used for fastening the heat sink to the
electrical device; and b) mounting at least one fin in the inner
chamber of the frame to separate the inner chamber of the frame
into at least two channels and each fin having two edges being
connected respectively to the two mounting sides of the frame.
6. The method of claim 5, wherein the frame is a
parallelepiped.
7. The method of claim 5, wherein each fin is rectangular.
8. The method of claim 6, wherein each fin is parallel with the two
non-mounting sides of the frame.
9. The method of claim 5, wherein the frame is made of extruded
aluminum; and the at least one fin is aluminum extruded from the
frame.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates to a heat sink used in
electrical devices, and more particularly to a heat sink used in an
un-interruptible power supply (UPS), which is assembled easily and
has excellent efficiency of heat dissipation.
[0003] 2. Description of the Related Art
[0004] Electrical devices, such as an un-interruptible power supply
(UPS), require excess heat to be removed leading to the development
of heat sinks.
[0005] Conventional methods of dealing with the excess heat are
such as selecting low heat generating elements, enlarging the heat
sink or increasing the fans to remove the heat out of the device.
Apparently, the methods have the disadvantage such as increasing
the cost, enlarging the size, and decreasing the performance. Each
of said methods goes against the object of the high power density
and miniaturization, so the best method is improving the efficiency
of the heat dissipation.
[0006] The heat sink of the electrical device is made of extruded
aluminum and has a surface area and fins that enlarge the surface
area to reduce heat in the electrical device according to a basic
overall heat-transfer equation:
Q=UA.sub.t(T.sub.ave-T.sub..infin.)
[0007] Wherein [0008] Q is heat transfer rate; [0009] U is overall
heat transfer coefficient; [0010] A is the surface area of the heat
sink; [0011] T.sub.ave is an average temperature in a surface of
the heat sink; [0012] T.sub..infin. is a temperature of
environment.
[0013] With reference to FIGS. 5 and 6, a UPS (1') has a front
panel, a rear panel, a fan (20), a conventional heat sink (30) and
electrical elements. The fan (20) is mounted on the rear of the UPS
(1'). The heat sink (30) is mounted in the UPS (1'), and has two
symmetrical frames (31). Each frame (31) is U-shaped, faces the
other frame to form a parallelepiped with an inner chamber and has
two sides and several fins (33).
[0014] The fins (33) are parallel extruded from the frame (31) and
have two surfaces that increase a surface area of the heat sink
(30). The electrical elements are mounted onto the frame (31), to
allow the generated heat to be easily transferred to the fins (33)
and removed by convection increased by the airflow forcing by the
fan (20). Therefore, the generated heat can be removed out of the
UPS (1').
[0015] However, all of the electrical elements mounted on the two
frames (31) do not be activated together. Because of the limitation
of design, usually only the electrical elements on the same frame
are activated in the same time, it rises the temperature of the
frame. But the other frame keeps a low temperature comparatively,
because of the electrical elements mounted on it aren't activated
in the same time. As a result, the whole heat sink (30) hasn't a
unit temperature, the other frame can't be used completely, so the
total efficiency of the heat dissipation decreased.
[0016] To overcome the shortcomings, the present invention provides
a heat sink for electrical device to mitigate or obviate the
aforementioned.
SUMMARY OF THE INVENTION
[0017] The primary objective of the present invention is to provide
a heat sink used in an electrical device, which is assembled easily
and has a high performance to dissipate the excess heat.
[0018] To achieve the objective, the heat sink for an electrical
device in accordance with the present invention has a frame and at
least one fin. The frame has an inner chamber. The fin is mounted
in the inner chamber of the frame to separate the inner chamber of
the frame into at least two channels. Therefore, heat generated
from any electrical element mounted on the heat sink will transfer
evenly to the heat sink of. The heat sink not only spreads heat
evenly, but also provides multiple channels to dissipate the excess
heat by convecting with the airflow. Besides, the heat sink only
has one frame, so assemble the heat sink with the electrical device
will be much easier and quicker.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Other objectives, advantages and novel features of the
invention will become more apparent from the following detailed
description of the preferred embodiment of the invention
illustrated in the accompanying drawings, wherein:
[0020] FIG. 1 is a perspective view of a heat sink in accordance
with the present invention;
[0021] FIG. 2 is a front view of the heat sink in FIG. 1;
[0022] FIG. 3 is a perspective view of the heat sink in FIG. 1
mounted in an un-interruptible power supply;
[0023] FIG. 4 is a side view of the heat sink in FIG. 3;
[0024] FIG. 5 is a perspective view of a conventional heat sink in
accordance with the prior art; and
[0025] FIG. 6 is a perspective view of the conventional heat sink
in FIG. 5 mounted in an un-interruptible power supply.
DETAILED DESCRIPTION OF THE INVENTION
[0026] With reference to FIGS. 1 and 3, a heat sink (10) in
accordance with the present invention is used in an electrical
device (1) and has a frame (11) and at least one fin (12).
[0027] The frame (11) may be a parallelepiped, may be made of
extruded aluminum and has an inner chamber. A rectangular frame
(11) has a width of 62 millimeters (mm), a height of 58 millimeters
(mm), two mounting sides (14) and two non-mounting sides (15). The
mounting sides (14) are defined opposite to each other and may be
4.1 mm thick. The non-mounting sides (15) are defined opposite to
each other, are perpendicular to the mounting sides (14) and may be
2.3 mm thick.
[0028] With further reference to FIG. 2, the at least one fin (12)
is mounted in the inner chamber of the frame (11) to separate the
inner chamber of the frame (11) into at least two channels (13).
When six fins (12) are mounted in the inner chamber, the fins (12)
are mounted at intervals and each interval is 6 mm thick. The at
least one fin (12) may be aluminum extruded from the frame (11) and
may be rectangular. Each rectangular fin (12) has two edges. The
edges of the fin (12) connect respectively to the mounting sides
(14) of the rectangular frame (11) to form at least two channels
(13). Each rectangular fin (12) is 1.9 mm thick. Preferably, six
rectangular fins (12) are used. The channels (13) are formed in the
frame (11).
[0029] With further reference to FIG. 3, the electrical device (1)
may be an un-interruptible power supply (UPS) and has a front, a
rear, the heat sink (10) of the present invention, at least one
ventilating device, a bracket (50) and a printed circuit board
(PCB) (51).
[0030] The heat sink (10) is mounted on the PCB (51)
[0031] The at least one ventilating device (20) communicates with
the channels (13) of the heat sink (10) and forces air to flow
through the channels (13) of the heat sink (10) to increase the
dissipation efficiency of the heat sink (10). The ventilating
device (20) may be a fan. The ventilating device (20) is mounted on
the rear of the UPS (1) and may be mounted on the frame (11) of the
heat sink.
[0032] The bracket (50) is mounted between the front and rear and
has two connecting edges and two surfaces. The connecting edges are
respectively connected to the front and rear of the UPS (1).
[0033] The PCB (51) is mounted to the bracket (50) and allows one
of the non-mounting sides (15) of the frame (11) to be mounted on
the PCB (51). Therefore, the heat sink (10) can be mounted or
easily connected indirectly to the PCB. The PCB (51) comprises a
first group of electrical elements and a second group of electrical
elements.
[0034] With further reference to FIG. 4, the first group of the
electrical elements is mounted on one mounting side (14) of the
frame (11) of the heat sink (10) and has multiple DC/DC
metal-oxide-semiconductor field-effect transistors (DC/DC MOSFET)
(41, 41a) and a rectifier (42). The DC/DC MOSFETs (41, 41a) are
mounted on one mounting side (14) of the frame (11) of the heat
sink (10) from the front to near the rear of the UPS (1), and the
DC/DC MOSFET nearest the rear being the first DC/DC MOSFET (41a).
The rectifier (42) is mounted on the side of the frame (11) on
which the DC/DC MOSFETs (41, 41a) are mounted, is adjacent to the
first DC/DC MOSFET (41a) at the rear of the UPS (1). The second
group of the electrical elements is mounted on the other mounting
side (14) of the frame (11) of the heat sink (10) and has a first
power factor correction diode (PFC diode) (43), a second PFC diode
(44), a first inverter insulated gate bipolar transistor (IGBT)
(45) and a second inverter IGBT (46). The first PFC diode (43), the
second PFC diode (44), the first inverter IGBT (45) and the second
inverter IGBT (46) are respectively mounted on the frame (11) of
the heat sink (10) from the front to the rear of the UPS (1).
[0035] While AC input power is normal, the UPS (1) will work in the
Line Mode, the rectifier (42), the PFC diode (43), the second PFC
diode (44), the first inverter IGBT (45) and the second inverter
IGBT (46) will be activated.
[0036] While AC input power is abnormal, the UPS (1) will use the
backup DC power and work in the Battery Mode, all the DC/DC MOSFETs
(41, 41a), the first inverter IGBT (45) and the second inverter
IGBT (46) will be activated.
[0037] Heat generated from any electrical elements will transfer
evenly to the heat sink (10). The ventilating device increases
airflow and the heat can be dissipated quickly and efficiently.
[0038] A method of manufacturing the heat sink for the electrical
device in accordance with the present invention, comprises two
steps:
[0039] a) step comprises making a frame which has an inner chamber,
two mounting sides and two non-mounting sides. The mounting sides
are defined as opposite to each other and are used for mounting
generating heat electrical elements. The non-mounting sides are
defined as opposite to each other and at least one of them is used
for fastening the heat sink to the electrical device.
[0040] b) step comprises mounting at least one fin in the inner
chamber of the frame to separate the inner chamber of the frame
into at least two channels. Each fin has two edges that are
connected respectively to the two mounting sides of the frame.
[0041] Examples: These experiments compare an efficiency of the
heat sink (10) of the present invention with a conventional heat
sink.
[0042] Test 1.
[0043] AC power is supplied to the UPS (1) at 170 volts until the
electrical elements hold a steady temperature. Some electrical
elements mounted on the heat sink of the present and the
conventional heat sink are measured, as shown in Table 1:
TABLE-US-00001 TABLE 1 Conventional Temperature Electrical heat
sink Present invention difference element (T/.degree. C.)
(T/.degree. C.) (T/.degree. C.) PFC diode (43) 66.7 49.4 -17.3
Second PFC diode (44) 67.2 54.3 -12.9 First inverter IGBT (45) 75.1
63 -12.1 Second inverter IGBT 73 66.7 -6.3 (46) First DC/DC MOSFET
52.1 50.3 -1.8 (41a) Rectifier (42) 64.9 69.4 +4.5
[0044] Text 2.
[0045] After test 1, DC power is supplied from a battery to the UPS
(1) and the UPS work in Battery Mode for 30 minutes. The
temperatures of some of the electrical elements mounted on the heat
sink of the present and the conventional heat sink are measured, as
shown in Table 2:
TABLE-US-00002 TABLE 2 Conventional Temperature Electrical heat
sink Present invention difference element (T/.degree. C.)
(T/.degree. C.) (T/.degree. C.) First DC/DC MOSFET 93.8 78.1 -15.7
(41a) Rectifier (42) 79.5 70.9 -8.6
[0046] Test 3.
[0047] After test 2, AC power is supplied to the UPS (1) at 272
volts. Temperatures of some electrical elements mounted on the heat
sink of the present and the conventional heat sink are measured, as
shown in Table 3:
TABLE-US-00003 TABLE 3 Conventional Temperature Electrical heat
sink Present invention difference element (T/.degree. C.)
(T/.degree. C.) (T/.degree. C.) PFC diode(43) 59.9 47.1 -12.8
Second PFC diode (44) 60.6 51.4 -9.2 First inverter IGBT (45) 67.3
59.7 -7.6 Second inverter IGBT 65.1 61.4 -3.7 (46) First DC/DC
MOSFET 49.8 47.3 -2.5 (41a) Rectifier (42) 50.3 49.7 -0.6
[0048] According to the foregoing tables, the heat sink (10) of the
present invention efficiently dissipates heat. Therefore, the heat
sink (10) of the present invention not only transfers heat evenly,
but also provides multiple channels (13) to dissipate heat by
convection. Additionally, because the heat sink (10) only has one
frame (11), the heat sink (10) can reduces assembly time and
difficulty of the electrical device (1).
[0049] Even though numerous characteristics and advantages of the
present invention have been set forth in the foregoing description,
together with details of the structure and function of the
invention, the disclosure is illustrative only. Changes may be made
in detail, especially in matters of shape, size and arrangement of
parts within the principles of the invention to the full extent
indicated by the broad general meaning of the terms in which the
appended claims are expressed.
* * * * *