U.S. patent application number 12/405556 was filed with the patent office on 2009-09-24 for device for preheating a component cooled by conduction and/or by convection.
This patent application is currently assigned to Kontron Modular Computers S. A.. Invention is credited to Philippe Oconte, Michel Ritondale, Serge Tissot.
Application Number | 20090236081 12/405556 |
Document ID | / |
Family ID | 39714004 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090236081 |
Kind Code |
A1 |
Oconte; Philippe ; et
al. |
September 24, 2009 |
DEVICE FOR PREHEATING A COMPONENT COOLED BY CONDUCTION AND/OR BY
CONVECTION
Abstract
The present invention relates to a device for preheating a
component cooled by conduction and/or by convection. The component
is in contact with a heat conductor and the device includes a
heater to heat the part, the device further including at least one
heat pipe having fluid within, to connect a heat dissipater with
the heat conductor, the dissipater and the part furthermore being
thermally insulated from one another. Freezing of fluid in the heat
pipe facilitates preheating of the component at low temperature.
The invention applies notably to the starting of components
subjected to low temperatures, for example, components installed in
systems on board aircraft.
Inventors: |
Oconte; Philippe; (Rocbaron,
FR) ; Tissot; Serge; (Hyeres, FR) ; Ritondale;
Michel; (Cuers, FR) |
Correspondence
Address: |
DARBY & DARBY P.C.
P.O. BOX 770, Church Street Station
New York
NY
10008-0770
US
|
Assignee: |
Kontron Modular Computers S.
A.
Toulon
FR
|
Family ID: |
39714004 |
Appl. No.: |
12/405556 |
Filed: |
March 17, 2009 |
Current U.S.
Class: |
165/104.26 |
Current CPC
Class: |
H01L 2224/16 20130101;
H01L 2224/73253 20130101; H01L 23/427 20130101; H01L 23/345
20130101 |
Class at
Publication: |
165/104.26 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2008 |
FR |
0801483 |
Claims
1. A device for preheating a component, the device comprising: a
heat conductor in thermal contact with the component; a heater to
heat the heat conductor; at least one heat pipe in thermal contact
with the heat conductor, the at least one heat pipe having a solid
phase that is thermally nonconductive, and a fluid phase that is
thermally conductive; and a heat dissipater in thermal contact with
the at least one heat pipe, the heat dissipater being thermally
insulated from the heat conductor when at least one heat pipe is in
the solid phase.
2. The device according to claim 1, wherein the heat-conducting
part comprises an excrescence of the heat pipe.
3. The device according to claim 1, wherein the heater comprises at
least one heating resistor placed adjacent to the heat
conductor.
4. The device according to claim 1, wherein the heat pipe further
comprises: a first end portion; a central portion adjacent to the
first end portion; and a second end portion adjacent to the central
portion, the second end portion opposite from the first end
portion, wherein the first end portion and the second end portion
are in physical contact with the heat dissipater, and the central
portion is in physical contact with the heat conductor.
5. The device according to claim 1, wherein the heat conductor and
the heat pipe are insulated in order to reduce the heat not
conducted to the heat dissipater.
6. The device according to claim 1, wherein a surface of the heat
conductor is rounded in order to reduce the heat loss by
radiation.
7. The device according to claim 1, wherein the heat conductor and
the heat pipe comprise low specific heat materials.
8. The device according to claim 1, wherein the heat pipe further
comprises a heat-conducting fluid having a solidification
temperature at least equal to or slightly below a predetermined
preheating temperature.
Description
[0001] The present application claims the benefit of French Patent
Application Serial No. 0801483, filed Mar. 18, 2008, which is
hereby incorporated by reference in its entirety.
[0002] The present invention relates to a device for preheating a
component cooled by conduction and/or by convection. The invention
applies notably to the starting of components subjected to low
temperatures, for example components installed in systems on board
aircraft.
[0003] Electronic components, for example computer processors, are
designed to operate in a limited temperature range, for example
between 0.degree. C. and 100.degree. C. Therefore, when these
components operate, they give off a quantity of heat which must be
cleared away in order to avoid exceeding the authorized top
temperature limit. The calories generated by the component are then
usually cleared away thanks to means of cooling by conduction or by
convection.
[0004] In certain situations, notably in a large number of onboard
systems, the components are placed in environments at low
temperatures--for example -40.degree. C. The starting of these
components at temperatures below their bottom operating temperature
limit poses a problem. In order to raise the temperature beyond
this bottom limit, it is possible for example to place a heating
resistor close to the component. But the cooling means that are
present in order to clear away the excess calories will oppose the
action of this heating resistor, thereby slowing, or even totally
nullifying its effect. There is therefore a contradiction between
the need, when cold, to preheat the component before starting it,
and the need, when hot, to clear away the calories generated by the
component.
[0005] As an example, taking as the hypothesis a conduction-cooled
15 W dissipation processor, it is necessary to preheat the
processor with 74 W of power for 9 minutes in order to bring its
temperature from -40.degree. C. to 0.degree. C. This waiting time
is often too long and this required power is usually too high to be
acceptable in onboard equipment.
[0006] An object of the invention is to allow a component
associated with cooling means to start in an environment the
temperature of which is below its minimum operating temperature.
Accordingly, the subject of the invention is a device for
preheating a component in contact with a heat-conducting part, the
device includes means for heating the said part, the device being
characterized in that it includes at least one heat pipe connecting
a heat dissipater with the said part, the said dissipater and the
said part furthermore being thermally insulated from one
another.
[0007] By preventing the clearing away of the calories by an effect
of freezing the fluid inside the heat pipe, the device according to
the invention makes it possible to rapidly raise the temperature of
the component in order to bring it to an acceptable level before it
is started. Preferably, the volume of the heat-conducting part is
small, so as to limit the energy used to preheat the component.
[0008] The heat-conducting part may be formed by an excrescence of
the heat pipe, so as to reduce the volume of material to be heated
and to enhance the efficiency of conduction between the heat pipe
and the heat-conducting part.
[0009] According to an embodiment of the device according to the
invention, each end of the heat pipe is placed in contact with the
heat dissipater, the central portion of the heat pipe being in
contact with the heat-conducting part. This embodiment makes it
possible to generate substantially symmetrical heat-clearing paths,
which facilitates the heat conduction, notably when the device
sustains accelerations hampering the movement of the fluid
contained in the heat pipe.
[0010] The heating means may include at least one heating resistor,
the said resistor being placed adjacent to the heat-conducting
part.
[0011] Advantageously, the heat-conducting part and the heat pipe
are insulated in order to limit the heat loss.
[0012] In addition, the heat-conducting part may be rounded on the
surface in order to reduce the heat loss by radiation.
[0013] Preferably, the heat-conducting part and the heat pipe are
made of low specific heat materials, such as, for example,
aluminium or copper.
[0014] According to an embodiment of the device according to the
invention, the heat-conducting fluid used in the heat pipe may be
chosen so that its solidification temperature is at least equal to
or slightly below (for example a few degrees Celsius less) the
preheating temperature to be achieved.
[0015] The device according to the invention may for example be
installed in an onboard system greatly limited in available power
and subjected to low temperatures.
[0016] Other features will appear on reading the following
detailed, non-limiting description given as an example with respect
to the appended drawings which represent:
[0017] FIG. 1, a top view of an embodiment of the device according
to the invention;
[0018] FIG. 2, a view in longitudinal section of the embodiment of
FIG. 1;
[0019] FIG. 3, a view in cross section of the embodiment of FIG.
1;
[0020] FIG. 4, a view of the heat-conducting part used in the
embodiment of FIG. 1.
[0021] The same reference numbers in various figures designate the
same elements.
[0022] FIG. 1, FIG. 2 and FIG. 3 show respectively a top view, a
view in longitudinal section and a view in cross section of an
embodiment of the device according to the invention.
[0023] The device 100 of the example includes a component 102
placed on a substrate 104, which substrate 104 is placed on a
printed circuit board 106. A heat-conducting part 108, for example
an aluminium block, is placed in contact with the component 102. In
the example of FIGS. 1, 2 and 3, the conducting part 108 is placed
adjacent to the top face of the component 102.
[0024] Furthermore, a heat dissipater 110, for example an aluminium
drain, is clamped by cold plates 112a, 112b and placed close to the
component, without touching it. In addition, all contact should be
avoided between the conducting part 108 and the heat dissipater 110
so that no direct heat path between the conducting part 108 and the
heat dissipater 110 is created. In the example, the heat dissipater
110 is a plate that is perforated so that the conducting part 108
can pass through without touching the plate.
[0025] The heat dissipater 110 should make it possible to clear
away a large proportion of the calories generated by the component
102. Therefore, a heat pipe 114 connects the heat dissipater 110 to
the conducting part 108 so that the heat pipe 114 establishes an
efficient heat-conducting path between the part 108 and the heat
dissipater 110 when the temperature of the heat pipe 114 is high
enough to allow the fluid contained in the heat pipe 114 to leave
the solid phase and to operate a heat-conducting circuit. On the
other hand, when the temperature of the heat pipe 114 is too low to
allow the fluid to melt, the heat-conducting circuit inside the
heat pipe 114 is impossible, which thermally insulates the
conducting part 108 from the heat dissipater 110. In the example,
the top face of the heat dissipater 110 is grooved 111 to the
dimensions of the heat pipe 114 and the heat pipe 114 is placed in
the groove 111, the area of contact between the heat pipe 114 and
the heat dissipater 110 thereby being maximized.
[0026] In order to raise the temperature of the component 102, a
heating resistor 116 is placed close to the latter. In the example,
the heating resistor 116 is placed adjacent to the conducting part
108, but in another embodiment, the heating resistor 116 is placed
on the heat pipe 114.
[0027] The heat-conducting part 108 notably plays a role of a heat
interface. Specifically, on the one hand, it carries the calories
originating from the heating resistor 116 to the component 102, and
on the other hand, when the component 102 is operating, the
heat-conducting part 108 carries the calories originating from the
component 102 to the heat pipe 114. According to one embodiment,
the heat-conducting part 108 is only an excrescence of the heat
pipe 114, the said excrescence 108 being fashioned at the time of
manufacture of the heat pipe 114.
[0028] When, initially, the device 100 is subjected to an ambient
temperature that is lower than the solidification temperature of
the fluid contained in the heat pipe 114 (at the internal pressure
of the heat pipe 114), the heating resistor 116 transmits calories
to the heat-conducting part 108, hence to the component 102 and the
heat pipe 114. Since the fluid contained in the heat pipe 114 is
solidified, the heat pipe 114 is inoperative; therefore, the
calories remain largely confined to the assembly formed from the
component 102, the heat-conducting part 108 and the heat pipe 114.
The temperature of this assembly increases until it reaches the
minimum operating temperature of the component 102. The component
can then be started without risk, then when the temperature of the
assembly {component 102, conducting part 108, heat pipe 114}
reaches or even exceeds the melting temperature of the fluid, then
a heat-conducting circuit can be made in the heat pipe 114, which
then carries away the received calories to the heat dissipater 110,
thus preventing the component 102 from overheating.
[0029] The fluid used in the heat pipe 114 is, for example, water.
However, fluids with different solidification temperatures may be
chosen in order to suit the conditions of use of the device 100.
For example, for components operating at very low temperatures,
alcohol may be a judicious choice for the heat pipe 114. Whatever
fluid is chosen, its solidification temperature should be below the
maximum operating temperature of the component 102.
[0030] In the example, each end of the heat pipe 114 is placed in
contact with the heat dissipater 110, the central portion of the
heat pipe 114 being in contact with the conducting part 108.
Therefore, the heat pipe 114 of the example includes an evaporator
on the conducting part 108 and two condensers, one at each end of
the heat pipe 114. This configuration results in obtaining two
substantially symmetrical heat clearance paths, which reduces the
distance of travel of the fluid from a condenser to the evaporator
and consequently makes it easier to establish a heat circuit.
Notably, this configuration improves the heat-conducting path
brought about by the heat pipe 114 when the device 100 sustains
accelerations--including natural gravitation--hampering the
movement of the fluid.
[0031] According to another embodiment, a first end of the heat
pipe 114 is placed adjacent to the conducting part 108, whereas its
second end is placed in contact with the heat dissipater 110, this
configuration resulting in a simple evaporator-condenser
circuit.
[0032] FIG. 4 shows a view of the heat-conducting part used in the
embodiment of FIG. 1.
[0033] The conducting part 108 of the example is in the form of an
arch. In other words, it is a parallelepiped of which one face 401
has been hollowed out to form a groove 410 to the dimension of the
heat pipe 114. The face 402 opposite to the hollowed-out face is
placed in contact with the component 102 (FIGS. 1, 2, 3) and a side
face 403 includes a sufficient area to place a heating resistor
thereon.
[0034] According to another embodiment of the device according to
the invention, the conducting part 108 may be made in many ways,
provided notably that the shape chosen allows good heat conduction
between the said part 108, the heat pipe 114 and the component 102.
Furthermore, several heating resistors may be placed adjacent to
the conducting part 108 in order to more rapidly raise its
temperature.
[0035] To take the example cited in the preamble of this
application, with a temperature of approximately -40.degree. C. and
a conduction-cooled 15 W dissipation processor, the use of a device
according to the invention makes it possible to reduce the power
needed to be supplied to 20 W and the preheating time to 40 seconds
in order to bring its temperature from -40.degree. C. to 0.degree.
C., compared with 74 W and 9 minutes that are necessary with a
conventional device, which represents approximately a gain
(time.times.power) with a factor of 50.
[0036] The device according to the invention may be used to bring a
component to its minimum specified temperature, for example
0.degree. C., before it is powered up or before it is initialized.
Nevertheless, if the available power is very low and/or the
acceptable, time for preheating is very short, the device may also
used to bring the component to a temperature below the specified
temperature, for example -20.degree. C.,--but all the same higher
than the ambient cold temperature--40.degree. C. This limited rise
in temperature may in effect be sufficient to achieve an acceptable
success rate during a cold sorting of the card fitted with the
component.
[0037] The device according to the invention preferably applies to
the electronic components present on cards cooled by conduction.
However, without departing from the context of the invention, the
device may equally apply to cards cooled by convection considering
that a cold wall may be formed by a convection radiator associated
with the component.
* * * * *