U.S. patent application number 12/548936 was filed with the patent office on 2010-03-04 for variable conductance heat pipe.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Shingo Hironaka, Shigetoshi IPPOSHI, Kuraki Kitazaki, Tetsuya Nagayasu, Yukio Sato.
Application Number | 20100051254 12/548936 |
Document ID | / |
Family ID | 41723606 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100051254 |
Kind Code |
A1 |
IPPOSHI; Shigetoshi ; et
al. |
March 4, 2010 |
VARIABLE CONDUCTANCE HEAT PIPE
Abstract
A variable conductance heat pipe is provided. The variable
conductance heat pipe includes a sealed container in which a
working fluid and a noncondensable gas are sealed. The sealed
container includes a heat receiving portion to which an element to
be cooled is provided, and heat radiating portion. An amount of
heat is supplied to the heat receiving portion when the element to
be cooled is in a waiting state.
Inventors: |
IPPOSHI; Shigetoshi; (Tokyo,
JP) ; Nagayasu; Tetsuya; (Tokyo, JP) ;
Hironaka; Shingo; (Tokyo, JP) ; Kitazaki; Kuraki;
(Tokyo, JP) ; Sato; Yukio; (Tokyo, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Chiyoda-ku
JP
|
Family ID: |
41723606 |
Appl. No.: |
12/548936 |
Filed: |
August 27, 2009 |
Current U.S.
Class: |
165/274 ;
165/104.26 |
Current CPC
Class: |
F28F 13/14 20130101;
F28D 15/06 20130101; H01S 5/02469 20130101; G03F 7/70891
20130101 |
Class at
Publication: |
165/274 ;
165/104.26 |
International
Class: |
F28F 27/00 20060101
F28F027/00; F28D 15/02 20060101 F28D015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2008 |
JP |
2008-219550 |
Claims
1. A variable conductance heat pipe comprising a sealed container
in which a working fluid and a noncondensable gas are sealed, the
sealed container including a heat receiving portion to which an
element to be cooled is provided, and heat radiating portion,
wherein an amount of heat is supplied to the heat receiving portion
when the element to be cooled is in a waiting state.
2. The variable conductance heat pipe according to claim 1, wherein
the amount of heat supplied to the heat receiving portion is an
amount which makes a temperature of the heat receiving portion when
the element to be cooled is in the waiting state to become a median
value or higher, the median value being a median of a temperature
Tr at which the element to be cooled operates and an ambient
temperature Te.
3. The variable conductance heat pipe according to claim 2, further
comprising a heater which supplies the heat receiving portion or
the element to be cooled with an amount of heat which makes the
temperature of the heat receiving portion when the element to be
cooled is in the waiting state to become the median value or
higher.
4. The variable conductance heat pipe according to claim 2, wherein
when the element to be cooled is in the waiting state, the element
to be cooled generates an amount of heat which makes the
temperature of the heat receiving portion to become the median
value or higher.
5. The variable conductance heat pipe according to claim 3, further
comprising a cooler provided to the heat radiating portion, wherein
the heater and the cooler cooperatively perform output control.
6. The variable conductance heat pipe according to claim 4, further
comprising a cooler provided to the heat radiating portion, wherein
the element to be cooled and the cooler cooperatively perform
output control.
7. The variable conductance heat pipe according to claim 1, wherein
the element to be cooled is covered with a heat insulating
material.
8. The variable conductance heat pipe according to claim 3, wherein
the heat receiving portion is covered with a heat insulating
material.
9. The variable conductance heat pipe according to claim 1, wherein
the element to be cooled is a semi-conductor laser device.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Japanese Patent
Application No. 2008-219550, filed on Aug. 28, 2008, the entire
subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a variable conductance heat
pipe for maintaining the temperature of equipment not in operation
at an arbitrary temperature with small electric power.
[0004] 2. Description of the Related Art
[0005] In a projector and a printer, in order to operate desirably,
the temperature of a main part such as a light source has to be
controlled to an appropriate temperature. As a temperature
controller for maintaining the temperature of such a main part of a
projector or printer to a temperature suitable for a desired
function, there has been proposed a heater-type temperature
controller for implementing a heat control through heating by a
heater, a heat pump-type temperature controller for implementing a
heat control through heating by a heater or through heating and
cooling by a heat pump, and a Peltier device-type temperature
controller for implementing a temperature control through current
control or current reversal by making use of the Peltier effect.
When a projector or printer becomes in operation, if a temperature
of the main part of the projector or printer in a waiting state
(not in operation) and a set temperature at which the main part
operates are different, a time for temperature control (a waiting
time) is required so that the temperature of the main part which is
not in operation is controlled to the set temperature by the
temperature controller. The larger the difference between the two
temperatures is, the longer the waiting time becomes, which is not
convenient for the user. Accordingly, there have been proposed a
projector and a printer in which a temperature controller is
maintained in operation to perform the temperature control in
advance even when the projector or printer is not in operation, so
as to reduce the waiting time when the projector or printer is
operated.
[0006] Further, an image forming apparatus detects a time period
during which a state continues in which no request is received from
the user, so as to switch operation modes and change set heating
temperatures to thereby realize the conservation of electric power
and enable a quick output in response to a request from the user
(for example, see JP-A-2005-49621 (page 13, FIG. 1)).
[0007] In a system having electronic equipment whose temperature
needs to be controlled, although the temperature of the electronic
equipment is desirably maintained in a state where the temperature
lies in the vicinity of a set temperature at which the electronic
equipment operates at all times in order to enable a quick output
in response to a request from the user, when the temperature of the
electronic equipment is maintained in such a state at all times,
the consumed power that is necessary to do so becomes large, which
results in a wasteful use of electric power. Then, in the image
forming unit described in JP-A-2005-49621, there is provided a
device configured to detect a time period during which a state
continues in which there is no request from the user, so as to
switch operation modes and reduce the set temperature at which the
electronic equipment is maintained heated, whereby the consumed
power of the electronic equipment while it is not in operation is
attempted to be reduced. In this approach, however, since equipment
for detecting an input from the user and a control mechanism for
enabling the detection are required, electric power for controlling
them is required separately, and since the electronic equipment is
heat controlled (heated) to the set temperature while heat is
radiated from a heat radiating unit of the electronic equipment,
the reduction effect of consumed power is not as high as
expected.
[0008] In addition, although there is an approach in which a
temperature control speed at which the temperature of electronic
equipment is controlled to its set temperature is made faster by
employing high-performance heating and cooling units, a high-level
control with a short response time becomes necessary, and such a
control is difficult to be applied to electronic equipment which is
small in size.
SUMMARY OF THE INVENTION
[0009] According to an aspect of the invention, there is provided a
variable conductance heat pipe comprising a sealed container in
which a working fluid and a noncondensable gas are sealed, the
sealed container including a heat receiving portion to which an
element to be cooled is provided, and heat radiating portion. An
amount of heat is supplied to the heat receiving portion when the
element to be cooled is in a waiting state.
[0010] According to the above-described configuration, the variable
conductance heat pipe can operate as a heat insulated type heat
pipe with less electric power by heat being supplied to the heat
receiving portion, the temperature of the heat receiving portion
can be set to an arbitrary temperature based on the amount of
noncondensable gas sealed in the variable conductance heat pipe,
and the temperature of the element to be cooled provided in the
heat receiving portion can easily be controlled to an arbitrary
temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Embodiments of the present invention will be described in
detail based on the following figures, wherein:
[0012] FIG. 1 is a diagram showing the configuration of a variable
conductance heat pipe according to Embodiment 1 of the
invention;
[0013] FIG. 2 is a chart showing the heat load depending property
of temperature for the variable conductance heat pipe and a normal
heat pipe;
[0014] FIG. 3 is a diagram showing the configuration of a variable
conductance heat pipe according to Embodiment 2 of the
invention;
[0015] FIG. 4 is a diagram showing the configuration of a variable
conductance heat pipe according to Embodiment 3 of the invention;
and
[0016] FIG. 5 is a diagram showing the configuration of a variable
conductance heat pipe according to Embodiment 4 of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
[0017] FIG. 1 is a sectional view showing a variable conductance
heat pipe according to Embodiment 1 of the invention. As shown in
FIG. 1, from one end portion, a variable conductance heat pipe 20
includes a sealed container 1 are a heat receiving portion 2 (an
evaporating portion), a heat insulating portion 3 (a transporting
portion), a heat radiating portion 4 (a condensing portion) and a
noncondensable gas reservoir portion 5. A working fluid (a liquid 6
and vapor 7 thereof) and a noncondensable gas 8 are sealed in an
interior of the sealed container 1. A heater 40 and an element to
be cooled 9 are provided to the heat receiving portion 2.
[0018] Next, the operation of the variable conductance heat pipe of
the Embodiment 1 will be described. When the element to be cooled 9
is activated to operate to obtain a desired function of the element
to be cooled 9, heat is generated in an interior of the element to
be cooled 9, whereby the temperature of the element to be cooled 9
is raised. The heat receiving portion 2 contacts (is connected to)
the element to be cooled 9 and the heat radiating portion 4
contacts (is connected to) a heat sink 10, whereby heat is
conducted from the element to be cooled 9 whose temperature is
higher to the heat receiving portion 2. The heat is then conducted
further to the liquid 6 residing within the heat receiving portion
2, and the heat conducted to the liquid 6 is absorbed by the liquid
6 in the form of latent heat or the liquid 6 is evaporated or
boiled, whereby vapor 7 is generated. The vapor 7 or the vapor 7
and the liquid 6 flow into the heat radiating portion 4 via the
heat insulating portion 3, where latent heat possessed by the vapor
7 is emitted to the heat radiating portion 4 while the vapor 7 is
condensed, the heat so emitted being radiated to the heat sink 10
whose temperature is lower than that of the heat radiating portion
4. As this occurs, the condensed liquid (the liquid 6) which is
generated by the vapor 7 being condensed is returned to the heat
receiving portion 2 from the heat radiating portion 4 via the heat
insulating portion 3 by virtue of gravity or capillary force. Heat
generated in the element to be cooled 9 is transmitted (discharged)
continuously to the heat sink 10 by circulation of these vapor 7
and liquid 6.
[0019] On the other hand, the noncondensable gas 8 which is sealed
within the interior of the sealed container 1 is caused to move to
the noncondensable gas reservoir portion 5 or a portion of the heat
radiating portion 4 which lies to face the noncondensable gas
reservoir portion 5 via the heat insulating portion 3 and the heat
radiating portion 4 as the vapor 7 or the vapor 7 and liquid 6 move
and is accumulated to be retained therein. When the noncondensable
gas 8 stays as described above, the vapor 7 is made difficult to
enter the noncondensable gas 8, thereby an interface 11 being
formed between the vapor 7 and the noncondensable gas 8. The vapor
7 pushes the noncondensable gas 8 continuously, whereby the
interface 11 is caused to move, and the pressures of the vapor 7
and the noncondensable gas 8 reach an equilibrium state, whereupon
the interface 11 stops moving, and its position is stabilized.
Consequently, (1) when the interface 11 reaches to be positioned in
the noncondensable gas reservoir portion 5, since the vapor 7 is
condensed over the whole heat radiating portion 4, a heat radiating
capability of 100% can be obtained, (2) when the interface 11 is
positioned within the heat radiating portion 4, since the area over
which the vapor 7 is condensed (the heat radiating area) is
reduced, the heat radiating capability decreases (the heat
radiating capability is variable in such a manner that 0%<heat
radiating capability<100%). In addition, (3) when the interface
11 is positioned within the heat insulating portion 3 or the heat
receiving portion 2, heat can be insulated (0% of the heat
radiating capability can be obtained). However, since part of heat
is caused to move by conduction of heat through the wall of the
sealed container 1, in reality, although it is not large, there
exists the heat radiating capability.
[0020] What has been described above is an operation principle of
the variable conductance heat pipe 20, and the temperature of the
element to be cooled 9 is controlled through expansion and
contraction of the noncondensable gas 8 by the element to be cooled
9 being activated to operate and is allowed to be maintained at an
arbitrary set temperature. However, when the element to be cooled 9
stops operating, the generation of vapor 7 is stopped, and the
temperatures of the noncondensable gas reservoir portion 5, the
heat radiating portion 4, the heat insulating portion 3, the heat
receiving portion 2 and the element to be cooled 9 are reduced to a
temperature equal to that of the heat sink 10. When the element to
be cooled 9 is activated to operate again in this state, a time
delay (a waiting time) occurs before the temperature of the element
to be cooled 9 is raised to the set temperature. Then, in this
embodiment, an amount of heat which enables the interface 11 to be
positioned to realize the states described under (2) and (3) above
is supplied by the heater 40 which is provided to the heat
receiving portion 2, so that the variable conductance heat pipe is
maintained operating in such a state that the heat radiating
portion 4 is generally heat insulated, whereby the temperature of
the heat receiving portion 2 is made to be maintained at an
arbitrary set temperature with a small amount of heat. In addition,
the heater 40 may be activated to operate irrespective of the
element to be cooled 9 being in operation or not, or the heater 40
may be operated cooperatively with the element to be cooled 9 in
such a manner that the heater 40 is activated to operate when the
element to be cooled 9 is not in operation (for example, a power
supply for the element to be cooled 9 and a power supply for the
heater 40 are switched over). In addition, the heater 40 may be
activated to operate by detecting that the element to be cooled 9
is not in operation (the heater 40 is switched on by detecting
electrically that the operation of the element to be cooled 9 is
switched off or by detecting it by a temperature sensor).
[0021] FIG. 2 shows an example of heat load depending property of
the temperature of the heat receiving portion 2 of the variable
conductance heat pipe 20 or how the temperature of the heat
receiving portion 2 of the variable conductance heat pipe 20 is
dependent on heat load. In the figure, a .diamond-solid. mark
denotes a normal heat pipe (which employs no noncondensable gas) in
which the temperature of a heat receiving portion increases
linearly as heat load increases (this is also true in a normal
cooling apparatus), and a .box-solid. mark denotes the variable
conductance heat pipe according to the Embodiment 1, in which the
temperature of the heat receiving portion reaches generally
50.degree. C. which is close to the set temperature (the
temperature at which the element to be cooled 9 operates, for
example, 53.degree. C.) by a heat load of the order of 5 W being
applied thereto. Namely, when the element to be cooled 9 is waiting
for activation while it is not in operation or when the element to
be cooled 9 is in a waiting state, if a heat amount of 5 W is made
to be generated in the heater 40, the element to be cooled 9 can be
heated to 50.degree. C. while it is in the waiting state. Even if
the element to be cooled 9 is activated to operate in this state
and the heat value when it is in operation reaches, for example, 50
W, since the temperature of the element to be cooled 9 only has to
be raised by 3.degree. C. to reach 53.degree. C., a time period
required for the element to be cooled 9 to reach its steady state
is short. In addition, in most electric apparatuses, since the
element to be cooled 9 can operate almost equally in a temperature
range of 50.degree. C. to 53.degree. C., the operation of the
element to be cooled 9 becomes stable immediately after it is
activated to operate. As is seen from FIG. 2, the normal heat pipe
requires about 65 W for the element to be cooled to be set to
53.degree. C., while the variable conductance heat pipe according
to the Embodiment 1 only requires a heat load which is one
thirteenth the heat load of the normal heat pipe before the
temperature which is extremely close to the set temperature can be
reached. When the normal heat pipe is used for cooling, since a
difference of as much as 33 k is generated between the set
temperature and the ambient temperature, when the heat control is
carried out through heating by the heater, the heat load of 65 W
has to be inputted to the element to be cooled while it is in the
waiting state. Because of this, a large amount of energy has to be
wasted, and in order to make the input of such a large heat load
happen, a heater of a large capacity, as well as wiring and power
supply for a large electric current have to be provided, which is
difficult to be realized on an electric apparatus which is small in
size.
[0022] As has been described above, according to Embodiment 1, the
time period required for the element to be cooled to reach from the
waiting state to the steady state, that is, the time period
required for the element to be cooled to obtain its desired
function is short, and the ensured temperature control can be
implemented. In addition, since almost a heat insulating state is
obtained while the element to be cooled 9 is in the waiting state,
the amount of heat to be supplied to the element to be cooled 9 in
the waiting state does almost not related to the heat radiating
capability of the heat radiating unit, and consequently, a highly
efficient heat radiating unit may be provided for maintaining the
set temperature at which the element to be cooled 9 operates at a
lower temperature.
[0023] In addition, according to Embodiment 1, an amount of heat
may be supplied to the heater 40, which makes the temperature of
the heat receiving portion 2 when the element to be cooled 9 is in
the waiting state to become a temperature between a temperature Tr
at which the element to be cooled 9 is in operation (53.degree. C.
in the example shown in FIG. 2) and an ambient temperature Te
(20.degree. C. in the example shown in FIG. 2). Preferably, an
amount of heat may be supplied to the heater 40 which makes the
temperature of the heat receiving portion 2 when the element to be
cooled 9 is in the waiting state to become a median value of Tr and
Te, that is, a temperature of (Tr+Te)/2(36.5.degree. C. in the
example shown in FIG. 2) or higher. As is seen from FIG. 2, by only
supplying the amount of heat which makes the temperature of the
heat receiving portion 2 when the element to be cooled 9 is in the
waiting state to become (Tr+Te)/2 to the heater 40, if the element
to be cooled 9 generates an amount of heat equal to or larger than
several watts upon the element to be cooled 9 being activated, the
temperature of the heat receiving portion 2 immediately reaches
50.degree. C. or higher, which exhibits the advantage of the
Embodiment 1. In addition, it is seen that when an amount of heat
which is larger than the amount of heat described above, that is,
an amount of heat which makes the temperature of the heat receiving
portion 2 when the element to be cooled 9 is in the waiting state
to become Te+0.8(Tr-Te) (a temperature lying 80% closer to the
temperature at which the element to be cooled 9 operates between
the ambient temperature and the temperature at which the element to
be cooled operates) or higher, the element to be cooled 9 more
preferably reaches faster the steady temperature at which it
operates.
[0024] Here, in the case of the element to be cooled 9 being a
semi-conductor laser device or laser diode (LD), by an electric
current which is smaller than its oscillation threshold being made
to flow to the LD, in place of heat being generated by the heater,
heat can be made to be generated by the LD or the element to be
cooled 9 itself. In the LD, when the electric current flowing
therethrough is smaller than its oscillation threshold, no laser
oscillation occurs, whereby no laser beam is outputted, that is,
the laser oscillation is in an inoperable state. The power inputted
into the LD in this state is lost, and therefore, heat is generated
by the LD itself in accordance with the value of electric current
which has flowed therethrough. In this configuration, the
temperature of the LD can be maintained at almost a constant
temperature both when the LD is not in operation (when no laser is
oscillated or the LD is in the waiting state) and when the LD is in
operation (when laser is oscillated) without using the heater 40.
Consequently, since the LD can be made to operate in a constant
oscillating state, that is, in an oscillating state which is free
from variation in oscillation frequency or output, the advantage of
the Embodiment 1 can particularly be exhibited.
[0025] As an application of the LD, there is raised a system in
which an LD for emitting red and blue visible light beams is used
as a light source of a video display unit. In the case of the video
display unit, light from the light source is captured by the eyes
of a human in the form of sensation as color or luminance. Since a
variation in color, which is frequency, or luminance, which is
output, is captured as a large variation in the sensation of the
human, in particular, the stability of the light source is required
in the video display unit. Because of this, in the system in which
the LD is used as the light source of the video display unit, the
advantage of Embodiment 1 is particularly important by which a
variation in operation of the LD is suppressed when the video
display unit is activated to operate. In addition, needless to say,
the heater 40 may be provided separately even when the element to
be cooled 9 is made up of the LD.
[0026] Here, while the configuration in which the temperature
increasing heater 40 is not provided separately but the element to
be cooled 9 generates heat by itself has been described by taking
the LD as the example, the invention is not limited to the
configuration so described. As long as the configuration is
provided in which the element to be cooled 9 generates heat by
itself by power inputted into the element to be cooled 9 which is
sufficiently smaller than power required for the element to be
cooled 9 to operate, the element to be cooled 9 may be made up of
any types of elements or devices having an electric input which
include other semiconductors than the LD or other electronic
devices.
[0027] In addition, needless to say, the configuration in which the
temperature increasing heater is not provided can also be applied
to Embodiments 2 to 4, which will be described later.
[0028] The sealed container 1 is an airtight container which stores
the liquid 6, vapor 7 and noncondensable gas 8 therein and may
preferably be made of a metal which produces almost no chemical
reaction between the liquid 6 and vapor 7 and the inner wall of the
sealed container 1. For example, in the case of the liquid 6 being
water, copper is preferably used as a material for the sealed
container 1, and in the case of the liquid 6 being ammonia, it is
recommendable to use a material such as aluminum or stainless steel
which does not produce a noncondensable gas through a chemical
reaction with the ammonia as a material for the sealed container
1.
[0029] The heat insulating portion 3 is a passage through which the
liquid 6, vapor 7 and noncondensable gas 8 move. The heat
insulating portion 3 may have its periphery exposed to a fluid such
as air or brought into contact with a structure to radiate heat
thereof. On the contrary, the heat insulating portion 3 may have a
heat insulating material provided thereon to insulate itself
against the loss of heat.
[0030] The heat radiating portion 4 has a function to cause the
vapor 7 condensed to be liquefied and radiate latent heat emitted
then to the heat sink 10. Projections may be provided on an inner
surface of the heat radiating portion 4 so as to increase the heat
conducting surface thereof for promotion of condensation of the
vapor 7, and a passage for suctioning condensed liquid may be
provided to make thin a condensed liquid film. In addition, fins
may be provided on an outer circumferential surface of the heat
radiating portion 4 so as to increase the heat conducting area for
promotion of radiation of heat to the heat sink 10. It is noted
that as has been described above, there may be a case where the
gas-liquid interface 11 is positioned in the interiors of the heat
insulating portion 3 and the heat radiating portion 4, and a part
of the heat insulating portion 3 and the heat radiating portion 4
in which the gas-liquid interface 11 is so positioned plays a role
of a passage or a container which accommodates the noncondensable
gas 8 therein.
[0031] The noncondensable gas reservoir portion 5 has a function to
accommodate the noncondensable gas 8 therein. There may be a case
where the noncondensable gas reservoir portion 5 accommodates
therein the liquid 6, vapor 7 and noncondensable gas 8 when the
variable conductance heat pipe is not in operation. The
noncondensable gas reservoir portion 5 is provided at an end
portion of the variable conductance heat pipe which lies farthest
from the heat receiving portion 2 with respect to the fluid
passageway of the variable conductance heat pipe. Preferably, a
configuration may be adopted in which the noncondensable gas
reservoir portion 5 is provided at an uppermost portion of the
constituent part of the variable conductance heat pipe, so that the
liquid 6 that has flowed thereinto is allowed to flow into the heat
radiating portion 4 downwards.
[0032] The liquid 6 is a liquid which can boil, evaporate and
condense and may consist of a single-component fluid such as water
and ammonia or a multi-component fluid such as an anti-freeze. The
vapor 7 is a gas resulting from vaporization of the liquid 6 or
part of the liquid 6. The noncondensable gas 8 is a gas which does
not condense in the working environment where it is used, and under
the normal environment, helium, argon, neon and nitrogen can
configure the noncondensable gas 8. Preferably, the noncondensable
gas is a gas which does not chemically react with the material of
the sealed container 1, the liquid 6, and the vapor 7, and an
inactive gas is preferably used. In addition, a non-condensable gas
may be used which is generated by challengingly causing the sealed
container 1 to react chemically with the liquid 6 in an initial
stage of sealing the liquid, vapor and noncondensable gas into the
sealed container 1.
Embodiment 2
[0033] FIG. 3 is a diagram showing the configuration of Embodiment
2 of the invention. While in Embodiment 1, the temperature of the
heat receiving portion 2 can be set to an arbitrary temperature
with less energy, when a main part 12 (of which the temperature
needs to be controlled) in the element to be cooled 9 lies away
from the heat receiving portion 2 (when a thermally interposed
material 13 is interposed therebetween), even in Embodiment 1,
there is generated a difference in temperature which corresponds to
a thermal resistance of the thermally interposed material 13 is
generated when the element to be cooled 9 is not in operation.
Then, in Embodiment 2, by providing a heater 40 near a main part 12
in the element to be cooled 9, a difference in temperature which is
generated by a heat input from the heater 40 and the thermal
resistance of a thermally interposed material 13 can be compensated
for, thereby making it possible to reduce a difference in
temperature between when the element to be cooled 9 is in operation
and not in operation.
[0034] In addition, in this case, since the difference in
temperature which is generated by the input of heat from the heater
40 and the thermal resistance of the thermally interposed material
13 can be generated also when the element to be cooled 9 is in
operation, the temperature of the main part 12 of the element to be
cooled 9 can be controlled accurately by the input of heat into the
heater 40.
[0035] In addition, by installing the heater 40 in the element to
be cooled 9, the wiring is eliminated from the cooler (the variable
conductance heat pipe 20), whereby the maintainability of the
variable conductance heat pipe 20 is enhanced. Further, by
providing a power supply and a control circuit which are provided
outside the element to be cooled 9 within the element to be cooled
9, the maintainability is enhanced further. The configuration in
which the heat 40 is installed in the interior of the element to be
cooled 9 can, needless to say, be applied to the element to be
cooled 9 which does not have the thermally interposed material 13
interposed between the heat receiving portion 2 and itself, that
is, the element to be cooled 9 which is configured in the way
described Embodiment 1.
Embodiment 3
[0036] FIG. 4 is a diagram showing the configuration of Embodiment
3 of the invention. In this configuration, a fan 14 is provided for
forcing a cooling fluid to flow through a heat radiating portion 4
of a variable conductance heat pipe 20, an element to be cooled 9
is provided within a temperature sensor 15, and the fan 14 and the
heater 40 are controlled with respect to outputs thereof by the
temperature sensor 15 and a control circuit 16, so as to provide an
optimum temperature control. The fan 14 may be a pump which causes
the cooling fluid to flow to the heat radiating portion. Namely,
the fan 14 may take any form, as long as it remains a cooler for
cooling the heat radiating portion 4.
[0037] By adopting this configuration, the temperature of the
element to be cooled 9 can be controlled through heating/cooling
via the variable conductance heat pipe 20, whereby not only can a
transition time to a set temperature and a waiting time of the user
be shortened, but also the temperature at which the element to be
cooled 9 can be controlled more accurately. Further, the outputs of
the cooler such as the pump or the fan 14 and the heater 40 can be
suppressed to minimum levels by the optimum control, thereby making
it possible to implement the temperature control with conserved
energy.
[0038] It is noted that while the case where the heater 40 is
provided has been described above, as is described in Embodiment 1,
the element to be cooled 9 may generate heat by itself without
providing the heater 40. In this case, the element to be cooled 9
and the cooler may cooperatively perform output control.
Embodiment 4
[0039] FIG. 5 is a diagram showing the configuration of Embodiment
4 of the invention. There is provided a configuration in which the
heat receiving portion 2 of the variable conductance heat pipe 20
and the element to be cooled 9 which includes a heater 40 are both
covered by a heat insulating material 17. By adopting this
configuration, not only can the temperature control efficiency of
the element to be cooled 9 be enhanced, but also heat radiation
while a set temperature is held is reduced so as to reduce the
amount of consumed power that is required when the element to be
cooled 9 is in a waiting state. To describe this in detail, while
the property shown in FIG. 2 are those for the case where the
element to be cooled and the heat receiving portion are not covered
by an insulating material, when both the heat receiving portion 2
and the element to be cooled 9 which includes the heater are
covered by the heat insulating material, in FIG. 2, property will
be such that the portion where the properties of the variable
conductance heat pipe rise is shifted leftwards. Consequently, an
amount of heat which is required to make the temperature of the
heat receiving portion when the element to be cooled 9 is in the
waiting state to a temperature in a case where the heat receiving
portion 2 and the element to be cooled 9 are not covered by the
heat insulating material becomes less than an amount of heat in a
case where the heat receiving portion and the element to be cooled
are not covered by the heat insulating material.
[0040] It is noted that while the configuration has been described
here in which both the heat receiving portion 2 and the element to
be cooled 9 which includes the heater are both covered by the heat
insulating material 17, even with a configuration in which either
one of the heat receiving portion 2 and the element to be cooled 9
is covered by the heat insulating material, there is provided the
advantage that compared with the configuration in which no heat
insulating material is used, the amount of consumed power required
when the element to be cooled is in the waiting state is
reduced.
[0041] While the present invention has been shown and described
with reference to certain exemplary embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
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