U.S. patent application number 11/344922 was filed with the patent office on 2006-08-03 for compact high-performance thermoelectric device for air cooling applications.
Invention is credited to Frank G. Li, Ligong Mei.
Application Number | 20060168969 11/344922 |
Document ID | / |
Family ID | 36755046 |
Filed Date | 2006-08-03 |
United States Patent
Application |
20060168969 |
Kind Code |
A1 |
Mei; Ligong ; et
al. |
August 3, 2006 |
Compact high-performance thermoelectric device for air cooling
applications
Abstract
This invention is a compact, high-performance thermoelectric
device for cooling air. Several variations on compact heat sinks
are disclosed as well as several optimized configurations for
maximized cooling effect, a mechanism to preventing overheating,
and robust configuration to withstand rugged applications such as
cooling automobile seats, air ducts, and power and temperature
control circuitry.
Inventors: |
Mei; Ligong; (Qianpu Nanqu,
CN) ; Li; Frank G.; (El Monte, CA) |
Correspondence
Address: |
Frank G. Li
11851 Lambert Ave
El Monte
CA
91732
US
|
Family ID: |
36755046 |
Appl. No.: |
11/344922 |
Filed: |
February 1, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60649718 |
Feb 3, 2005 |
|
|
|
Current U.S.
Class: |
62/3.7 ;
62/3.3 |
Current CPC
Class: |
H01L 35/30 20130101;
H01L 35/00 20130101; F25B 2321/025 20130101; F25B 2321/0212
20130101; F25B 21/02 20130101; F25B 2321/023 20130101 |
Class at
Publication: |
062/003.7 ;
062/003.3 |
International
Class: |
F25B 21/02 20060101
F25B021/02 |
Claims
1. A thermoelectric heat exchange device comprising: A ceramic
thermoelectric module that, with the application of an electrical
current, will achieve a hot side and a cold side; A temperature
sensor embedded inside said hot side of said thermoelectric module
that measures the temperature at the surface of said hot side and
generates an output signal; Said temperature sensor connected to a
program circuit such that said electric current is regulated as a
function of said output signal; A heat sink attached to said hot
side over which air will pass, resulting in the heating of the air;
A heat sink attached to said cold side over which air will pass,
resulting in the cooling of the air.
2. A thermoelectric heat exchange device as defined in claim 1,
wherein the heat sink attached to said hot side is primarily
composed of copper.
3. A thermoelectric heat exchange device as defined in claim 2,
wherein the heat sink attached to said hot side is shaped as a
compressed accordion with the ridge lines of the accordion arranged
in straight lines that run parallel to one another.
4. A thermoelectric heat exchange device as defined in claim 2,
wherein the heat sink attached to said cold side is shaped as a
compressed accordion with the ridge lines of the accordion arranged
in wavy lines that run parallel to one another.
5. A thermoelectric heat exchange device as defined in claim 1,
wherein the heat sink attached to said cold side is primarily
composed of aluminum.
6. A thermoelectric heat exchange device as defined in claim 5,
wherein the heat sink attached to said hot side is shaped as a
compressed accordion with the ridge lines of the accordion arranged
in straight lines that run parallel to one another.
7. A thermoelectric heat exchange device as defined in claim 5,
wherein the heat sink attached to said cold side is shaped a
parallel, flat, planar fins that are arranged parallel to one
another.
8. A thermoelectric heat exchange device as defined in claim 7,
wherein additional blocking fins are added perpendicular to said
planar fins in order to elongate the path which air travels over
the heat sink.
9. A thermoelectric heat exchange device as defined in claim 1,
wherein a metal bracket is used to package the assembly.
10. A thermoelectric heat exchange device as defined in claim 1,
wherein thermal glue is used to attach the components of the
assembly to one another.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present Utility patent application claims priority
benefit of the U.S. provisional application for patent No.
60/649,718 filed on Feb. 3, 2005 under 35 U.S.C. 119(e). The
contents of this related provisional application are incorporated
herein by reference.
FIELD OF INVENTION
[0002] This invention discloses a compact and high-performance
thermoelectric heat exchange device (TED) which can be used in an
air-conditioning system to deliver cold air and cool any object,
such as an automobile seat.
BACKGROUND
[0003] Thermoelectric cooling modules are also known as Peltier
modules and are heat pumps that operate on the physical principles
established over a century ago by Jean Charles Athanase Peltier in
France.
[0004] In a thermoelectric (TE) module, semiconductor materials
with dissimilar characteristics are connected electrically in
series and thermally in parallel, so that two junctions are
created. The semiconductor materials are N and P-type, and are so
named because either they have more electrons than necessary to
complete a perfect molecular lattice structure or not enough
electrons to complete a lattice structure. The extra electrons in
the N-type material and the holes left in the P-type material are
called "carriers" and they move the heat energy from the cold to
the hot junction.
[0005] A typical TE module is comprised of two ceramic substrates
that serve as a foundation and electrical insulation for P-type and
N-type semiconductor couples that are connected electrically in
series and thermally in parallel between the ceramics. The ceramics
also serve as insulation between the modules' internal electrical
elements and an electrically conductive material, usually copper
pads attached to the ceramics, and maintains electrical connections
inside the module.
[0006] With the application of Direct Current (DC) to the TE
module, heat is absorbed on the cold side of the ceramic, passes
through the semiconductor material, and is dissipated at the hot
side of the ceramic.
[0007] A heat sink should be attached to the hot side of the
ceramic for efficiently dissipating the heat from the TE module to
the surrounding environment. Without a heat sink, the TE module
would overheat and fail within seconds. Another heat sink may be
attached to the cold side of the ceramic to cool the air or any
other substance that passes through the heat sink.
[0008] Such a configuration of the thermoelectric assembly is
generally known as thermoelectric device (TED). This type of TED,
along with other components, such as a blower, air duct, power
supply, temperature sensing and control loop, can be used as a heat
exchange device in an air conditioning system to deliver
conditioned cold air for cooling applications. Some examples may be
found in U.S. Pat. No. 5,623,828, which discloses a thermoelectric
air cooling device for supplying cooled air to the driver or
passengers of a vehicle; U.S. Pat. No. 6,758,193, which discloses a
super-chilled air induction system used to reduce the air
temperature in an air-fuel mixture during operation of an internal
combustion engine; U.S. Reissue Pat. No. RE38,128, which discloses
an integrated temperature climate control system for an automotive
seat that comprises one heat sink that is used on both sides of the
TED, with a switch to reverse the polarity of the current; and U.S.
Pat. No. 5,547,019, which discloses a thermoelectric intercooler
for heating or cooling the gas exiting a compressing stage of a
turbocharger in an automobile. Some of these patents focus on
integrating a thermoelectric device with the existing engine parts
to improve engine performance. In U.S. Pat. No. 6,758,193, the
thermoelectric device only indirectly cools the air with liquid
coolant. In U.S. Pat. No. 5,547,019, the thermoelectric device may
be used for both cooling and heating. In U.S. Reissue Pat. No.
RE38,128, because the heat sink is the same on both sides, and the
polarity is simply reversed, the heat sink is not as effective at
dissipating heat, and the performance of the cooling function is
not as strong or efficient as it could be. U.S. Pat. No. 5,623,828
details a thermoelectric device which directly cools air passing
through the heat sink that is attached to the cold side of the
thermoelectric module, but is not very efficient, and is not
suitable for placement in an automobile seat.
[0009] However, no mechanism is disclosed in the prior art to
prevent potential overheating of the TE module during prolonged
operation or extreme conditions. Further, none of these devices
discloses a TE module of sufficient robustness, durability, and
compactness as desired.
[0010] Also, the performance of the heat sinks directly affects the
performance of the thermoelectric device. In a TED, a temperature
sensor is generally inserted into the heat sink on the hot side to
measure the temperature of the heat sink, so that overheating of
the thermoelectric module can be prevented. However, due to the
temperature difference between the heat sink and the hot ceramic
side of the module, the temperature measured does not accurately
reflect the temperature of the module and overheating could,
nevertheless, result because of this inaccuracy. Thus, there is a
long felt need in the industry for a temperature sensor that
accurately measures the temperature of the hot ceramic side of the
module rather than within the heat sink. Accordingly, it is an aim
of this invention to disclose an innovative and highly efficient
design of heat sink.
SUMMARY OF THE INVENTION
[0011] This invention is directed towards overcoming the above
shortcomings by providing a compact thermoelectric device with an
optimized configuration for maximized cooling effect, mechanism for
preventing overheating, and robustness to withstand rugged
applications such as cooling automobile seats, air ducts, and power
and temperature control circuitry.
[0012] This thermoelectric device consists of a Peltier
thermoelectric module, hot side heat sink, cold side heat sink, a
temperature sensor such as Negative Temperature Coefficient (NTC)
thermistor directly embedded inside the thermoelectric module,
assembly material such as thermal glue or metal bracket, and a
foam-type insulation material to fill in the space along the side
of the heat sink and minimize heat loss. A separate heat sink is
mounted to each side of the thermoelectric module using either
thermal glue or a metal bracket with thermal grease at the
interface, which can enhance the heat transfer and provide
additional rigidity. The said device, if placed in a snuggly shaped
plastic enclosure with one air intake port and two air exit ports,
can be positioned at the discharge of a blower and used as a heat
exchange device to cool one portion of the divided air stream while
the other portion of the air passes over the exposed hot side heat
sink and is heated.
[0013] The more effective the heat dissipation system for the hot
side of the TE module, the cooler the cold side will be and the
more efficiently the TE unit will operate. When power is applied to
the module, the hot side of the module will begin ejecting its heat
to the heat sink causing its temperature to rise. The ability of
the heat sink to dissipate this heat as well as the heat being
pumped from the cold side will determine the actual operating
temperature of the hot side and thus, the cold side. The lower the
thermal resistance of the heat sink on the hot side, the lower the
temperature on the cold side will be.
[0014] In one of the disclosed embodiments, a copper heat sink is
used for the hot side for its better thermal conductivity relative
to aluminum. Rather than a conventional extruded or bonded heat
sink with fins, this copper heat sink is fabricated in the shape of
a compressed accordion, allowing for more surface area and greater
heat dissipation. The heat sink fins are formed in straight
channels because such a configuration has less resistance to
airflow and thus, greater heat dissipation.
[0015] Accordingly, the main purpose of the heat sink on the cold
side for this device is to let the air passing through undergo as
much heat exchange as possible with the cold side of the ceramic.
The longer the path of the air traveling through over the cold
side, the greater the heat exchange that occurs, hence the lower
the temperature of the air passing over the heat sink. Two
variations on the heat sink shape are disclosed that achieve this
purpose: one is a compressed accordion shape copper heat sink as
described above but with "wave" type ridge lines, the other one is
an aluminum heat sink with fins in an "S" shape. Both are
fabricated to maximize the length of air passage over the cold side
of the heat sink. These two variations are disclosed because, in
tests, they have provided the best performance.
[0016] As mentioned above, two methods of assembly can be used to
package the TED: a metal bracket or thermal glue. When the metal
bracket is used, thermal grease is applied at the interface between
heat sink and ceramic of the TE module. The thermal glue results in
an even lighter package because of reduction of metal parts.
Combined with a rather small footprint of the device (approximately
45.times.45.times.24 mm in the current configuration), the result
is a relatively compact and robust device that can be used in
demanding conditions such as the vibration within automobiles.
[0017] In order to accurately control the temperature of the hot
side of the TE module and prevent possible overheating, an NTC
thermistor is embedded within the TE module for direct contact with
the hot side. The data from the thermistor measurement is fed to a
control loop that is used to supply the power to the TE module.
Thus, if the temperature measured from the hot side exceeds a
certain threshold, the power supply to the TE module can be cut off
to eliminate possible detrimental damage to the TE module.
[0018] One advantage of this configuration is its fast response
time and high cooling efficiency. Within 10 seconds of applying
power to the TE device, a several degree reduction of the
temperature measured at the exit point of the cold side air is
achieved.
[0019] Another advantage of the invention is that air passing over
the cold side can be directed outwards to cool other objects, such
as automobile seats.
[0020] Other variations and advantages of this invention will
become apparent from the following descriptions of several possible
embodiments of the invention, taken in conjunction with the
accompanying drawings, which illustrate, by way of example, the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 illustrates a perspective view of an embodiment of
the invention in which a straight copper heat sink is used on the
hot side, a wave type copper heat sink is used on the cold side,
and the device is assembled using a metal bracket.
[0022] FIG. 2 illustrates a perspective view of another embodiment
of the invention in which a straight copper heat sink is used on
the hot side, an aluminum heat sink is used on the cold side, and
the device is assembled using a metal bracket.
[0023] FIG. 3 illustrates a perspective view of another embodiment
of the invention in which a straight copper heat sink is used on
the hot side, a wave type copper heat sink is used on the cold
side, and the device is assembled using thermal glue.
[0024] FIG. 4 illustrates a perspective view of another embodiment
of the invention in which the straight copper heat sink is used on
the hot side, aluminum heat sink is used on the cold side, and the
device is assembled using thermal glue.
[0025] FIG. 5A illustrates a perspective view of the straight
copper heat sink prior to being compressed into its final
shape.
[0026] FIG. 5B illustrates a perspective view of the straight,
copper heat sink in its relaxed condition, prior to assembly.
[0027] FIG. 6A illustrates a perspective view of the "wave" type
copper heat sink in its final compressed shape.
[0028] FIG. 6B illustrates a perspective view of the "wave" type
copper heat sink in its relaxed condition, prior to assembly.
[0029] FIG. 7A is a perspective view of the S-shaped aluminum heat
sink.
[0030] FIG. 7B illustrates a top plan view of the S-shaped aluminum
heat sink.
[0031] FIG. 7C is a side elevation view of the S-shaped aluminum
heat sink.
[0032] FIG. 8A illustrates a perspective view of the TE module with
NTC thermistor directly embedded beneath the hot side of the
ceramic at the center of the thermoelectric module.
[0033] FIG. 8B illustrates a perspective view of the TE module with
A NTC thermistor directly embedded beneath the hot side of the
ceramic at one end of the thermoelectric module.
DETAILED DESCRIPTION
[0034] FIG. 1 illustrates a perspective view of an embodiment of
the invention in which a straight copper heat sink is used on the
hot side, a wave type copper heat sink is used on the cold side,
and the device is assembled using a metal bracket. A TE module 22
is sandwiched between "straight" copper heat sink 24 and "wave"
copper heat sink 26. An NTC thermistor 21 is attached to TE module
22 at the center of the hot side of the ceramic. A foam insulation
material 23 and 25 is used to fill the space along each side of the
heat sink, which would otherwise allow air to pass without coming
in full contact with the heat sink passages. Metal brackets 27 are
used to assemble the TED 20. The electric leads 31 and 33 of the
thermoelectric module can be connected to the positive and negative
leads of a DC power source.
[0035] FIG. 2 illustrates a perspective view of another embodiment
of the invention in which a straight copper heat sink is used on
the hot side, an aluminum heat sink is used on the cold side, and
the device is assembled using a metal bracket. The TED 30 has a
straight copper heat sink 24 on its hot side and an S-shaped
aluminum heat sink 28 on its cold side. TE module 22 is sandwiched
between the "straight" copper heat sink 24 and S-shaped aluminum
heat sink 28. An NTC thermistor 21 is inserted into TE module at
the center of the hot side of the ceramic. A foam insulation
material 23 and 25 is used to fill the space along each side of the
heat sink which would otherwise allow air to pass without coming in
full contact with the heat sink passages. Metal brackets 27 are
used to assemble the TED 30. The electric leads 31 and 33 of the
thermoelectric module can be connected to the positive and negative
leads of a DC power source.
[0036] FIG. 3 illustrates a perspective view of another embodiment
of the invention in which a straight copper heat sink is used on
the hot side, a wave type copper heat sink is used on the cold
side, and the device is assembled using thermal glue. A TE module
22 is sandwiched between a "straight" copper heat sink 24 on the
hot side and a "wave" copper heat sink 26 on the cold side. An NTC
thermistor 21 is inserted into the TE module 22 at the end of the
hot side of the ceramic. The TED 40 is assembled using thermal glue
29. The electric leads 31 and 33 of the thermoelectric module can
be connected to the positive and negative leads of a DC power
source.
[0037] FIG. 4 illustrates a perspective view of another embodiment
of the invention in which the straight copper heat sink is used on
the hot side, aluminum heat sink is used on the cold side, and the
device is assembled using thermal glue. A TED 50 has a straight
copper heat sink 24 on its hot side and an S-shaped aluminum heat
sink 28 on its cold side. TE module 22 is sandwiched between
"straight" copper heat sink 24 and S-shaped aluminum heat sink 28.
An NTC thermistor 21 is inserted into TE module at the end of the
hot side of the ceramic. The TED is assembled using thermal glue
29. The electric leads 31 and 33 of the thermoelectric module can
be connected to the positive and negative leads of a DC power
source.
[0038] FIG. 5A illustrates a perspective view of the straight
copper heat sink in its final compressed condition. At this stage,
the heat sink 24 has triangle shaped air passages or channels. The
ridge lines of these passages or channels are straight so this
configuration has less air resistance and, thus, air flow is
greater with this relative to a "wave" type copper heat sink 26, as
shown in FIGS. 6A and 6B.
[0039] FIG. 5B illustrates a perspective view of the straight
copper heat sink in its relaxed condition prior to assembly. After
being compressed horizontally along the axis parallel with the top
and bottom surface, the heat sink's 24 triangle shaped air passages
or channels are formed to allow for maximum heat transfer between
the heat sink and the passing air.
[0040] FIG. 6A illustrates a perspective view of the "wave" type
copper heat sink 26 in its final compressed shape with its triangle
shaped air passages or channels formed. The ridge lines of these
passages or channels are wave shaped so this copper heat sink has
more air resistance and hence the air flow is less as compared to
the straight line copper heat sink 25, in FIGS. 5A and 5B.
[0041] FIG. 6B illustrates a perspective view of the "wave" type
copper heat sink 26 in its relaxed condition prior to assembly.
After being compressed horizontally along the axis parallel to the
top and bottom surface, its triangle shaped air passages or
channels are formed.
[0042] FIG. 7A is a perspective view of the S-shaped aluminum heat
sink. FIG. 7B illustrates a top plan view of the S-shaped aluminum
heat sink. FIG. 7C is a side elevation view of the S-shaped
aluminum heat sink. In each drawing, an S-shaped heat sink 26 is
diagrammed from a different perspective. Unlike conventional
aluminum heat sinks that feature multiple fins extending from the
base plate with same the length, this heat sink features partially
blocked air entrances and exits at the aluminum fins. These
blockages serve to form the "S" shape of the configuration and
allow for greater air resistance and air flow path compared to
conventionally shaped fins. Thus, the air exiting the heat sink
will allow more net cooling for colder temperatures.
[0043] FIG. 8A illustrates a perspective view of the TE module with
NTC thermistor directly embedded beneath the hot side of the
ceramic at the center of the thermoelectric module. A TE module 22
with NTC thermistor 21 directly embedded underneath the hot side of
the ceramic is illustrated. The thermistor 21 is shown placed in at
the center beneath the TE module 22. The electric leads 31 and 33
of the thermoelectric module can be connected to the positive and
negative leads of a DC power source.
[0044] FIG. 8B illustrates a perspective view of the TE module with
an NTC thermistor directly embedded beneath the hot side of the
ceramic at one end of the thermoelectric module. A TE module 22 is
shown with a thermistor 21 beneath and at the end of the TE module.
The thermistor 21 needs to be in thermal contact with the ceramic
plate on the hot side of the TE module but electrically insulated
from the thermocouples within the TE module. This is done during
the fabrication process of the TE module and cannot be accomplished
after the TE module is fabricated. The electric leads 31 and 33 of
the thermoelectric module can be connected to the positive and
negative leads of a DC power source.
[0045] The four thermoelectric devices depicted in these four
embodiments represent some possible variations in the present
invention based on different combinations between two different
types of heat sinks on the cold side, and two different methods of
assembling. More variations can be formed by varying the position
of the NTC thermistor.
[0046] Any of the said thermoelectric devices, 20, 30, 40 or 50,
can be placed in a plastic enclosure (not shown) with one air
intake port and two air outlet ports. This plastic enclosure should
house the TED rather snuggly, so that any space between the TED and
the internal wall of the enclosure is minimized as is any possible
air leakage. The orientation of the TED in this plastic housing
should be such that the intake port is aligned with the passages or
channels on the heat sinks. One of the outlet ports on the
enclosure should be situated close to the cold side of the heat
sink, while the other outlet port close to the hot side of the heat
sink. TE module 22 would act as an air-diverter to divide the
singular air source into two air streams, a hot air stream and a
cold air stream. The hot air stream may be treated as waste stream
and exhausted, and the cold side air stream can be used to cool an
object.
[0047] The electric leads 31 and 33 of the thermoelectric module
can be connected to the positive and negative leads of a DC power
source. The operating range of the thermoelectric module is between
6 to 16 Volts. The power applied to the TE module can be controlled
by a Power Width Modulation circuitry that is also connected to a
temperature control circuitry to control the temperature of the
object being cooled, or other similar circuitry. The two leads of
NTC thermistor 21 can be connected to this power control circuitry
to further regulate supply of the power to the TE module. When the
signal from the thermistor 21 indicates that the temperature of the
hot side of the TE module exceeds a preset value, the power supply
to the TE module would be shut off to prevent any overheating of
the TE module and TED.
[0048] While certain exemplary embodiments of the invention have
been described and shown in the accompanying drawings, it is to be
understood that such embodiments are merely illustrative of and not
restrictive on the broad aspects of the invention, and that the
embodiments of the invention are not to be limited to the specific
constructions and arrangements shown and described, because various
other modifications are possible.
* * * * *