U.S. patent application number 17/671197 was filed with the patent office on 2022-05-26 for cooling system for a computer system.
This patent application is currently assigned to Asetek Danmark A/S. The applicant listed for this patent is Asetek Danmark A/S. Invention is credited to Andre Sloth Eriksen.
Application Number | 20220164014 17/671197 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-26 |
United States Patent
Application |
20220164014 |
Kind Code |
A1 |
Eriksen; Andre Sloth |
May 26, 2022 |
COOLING SYSTEM FOR A COMPUTER SYSTEM
Abstract
The invention relates to a cooling system for a computer system,
said computer system comprising at least one unit such as a central
processing unit (CPU) generating thermal energy and said cooling
system intended for cooling the at least one processing unit and
comprising a reservoir having an amount of cooling liquid, said
cooling liquid intended for accumulating and transferring of
thermal energy dissipated from the processing unit to the cooling
liquid. The cooling system has a heat exchanging interface for
providing thermal contact between the processing unit and the
cooling liquid for dissipating heat from the processing unit to the
cooling liquid. Different embodiments of the heat exchanging system
as well as means for establishing and controlling a flow of cooling
liquid and a cooling strategy constitutes the invention of the
cooling system.
Inventors: |
Eriksen; Andre Sloth; (Nibe,
DK) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Asetek Danmark A/S |
Aalborg East |
|
DK |
|
|
Assignee: |
Asetek Danmark A/S
Aalborg East
DK
|
Appl. No.: |
17/671197 |
Filed: |
February 14, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16796086 |
Feb 20, 2020 |
11287862 |
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17671197 |
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15991384 |
May 29, 2018 |
10599196 |
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16796086 |
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15626706 |
Jun 19, 2017 |
10078355 |
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15991384 |
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13861593 |
Apr 12, 2013 |
9733681 |
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15626706 |
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11919974 |
Jan 6, 2009 |
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PCT/DK2005/000310 |
May 6, 2005 |
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13861593 |
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International
Class: |
G06F 1/20 20060101
G06F001/20; H01L 23/473 20060101 H01L023/473; F04D 15/00 20060101
F04D015/00; H05K 7/20 20060101 H05K007/20 |
Claims
1-17. (canceled)
18. A liquid cooling system for cooling a heat-generating component
of a computer, comprising: a double-sided chassis adapted to mount
a pump configured to circulate a cooling liquid, the pump
comprising a motor with stationary windings and a rotor comprising
an impeller, the impeller positioned on one side of the chassis and
the stationary windings being positioned on an opposite side of the
chassis electrically isolated from the cooling liquid; a reservoir
adapted to pass cooling liquid therethrough, the reservoir
including: a pump chamber including the impeller, and: a thermal
exchange chamber positioned below the pump chamber and vertically
spaced apart from the pump chamber; wherein the pump chamber and
the thermal exchange chamber being separate enclosed chambers that
are fluidly coupled together by at least one passage; a
heat-exchanging interface forming a boundary wall of the thermal
exchange chamber, the heat-exchanging interface has an outer
surface configured to be placed in thermal contact with a surface
of a heat-generating component; a heat radiator adapted to pass the
cooling liquid therethrough, the heat radiator being fluidly
coupled to the reservoir via fluid conduits, the heat radiator
being configured to dissipate heat from the cooling liquid; and a
fan configured to direct air through the heat radiator, the fan
being driven by a motor separate from the motor of the pump;
wherein the thermal exchange chamber includes: an inlet that
fluidly couples the thermal exchange chamber to the pump chamber
via at least one passage positioned between a first end and a
second end of the thermal exchange chamber; wherein the thermal
exchange chamber includes at least one outlet configured to direct
cooling liquid out of the thermal exchange chamber, the at least
one outlet positioned at one or more of the first end or the second
end of the thermal exchange chamber.
19. The cooling system of claim 18, wherein the double-sided
chassis comprises a recess configured to house a stator of the pump
motor.
20. The cooling system of claim 19, wherein the stationary windings
are operatively connected to the stator housed in the recess.
21. The liquid cooling system of claim 18, wherein the chassis
forms a boundary wall of the pump chamber.
22. The liquid cooling system of claim 18, wherein the thermal
exchange chamber further includes a plurality of channels is
defined by a plurality of fins.
23. The cooling system of claim 18, wherein the pump is a
centrifugal pump.
24. A liquid cooling system for cooling a heat-generating component
of a computer, comprising: a reservoir configured to circulate a
cooling liquid therethrough, the reservoir including: a pump
chamber housing a rotor having an impeller and defined at least in
part by an impeller cover and a double-sided chassis, the impeller
being positioned on one side of the chassis and at least one sensor
for sensing the angular position of the rotor is positioned on an
opposite side of the chassis, wherein the pump chamber includes: an
inlet defined by the impeller cover positioned below a center of
the impeller configured to enable a cooling liquid to flow into the
center of the pump chamber; an outlet defined by the impeller cover
positioned tangentially to the circumference of the impeller; a
thermal exchange chamber configured to be disposed between the pump
chamber and a heat-generating component when the system is
installed on a heat-generating component; a heat-exchanging
interface forming a boundary wall of the thermal exchange chamber,
the heat-exchanging interface has an outer surface configured to be
placed in thermal contact with a surface of a heat-generating
component and an inner surface that defines a plurality of channels
that direct the flow of the cooling liquid within the thermal
exchange chamber; a heat radiator adapted to pass the cooling
liquid therethrough, the heat radiator being fluidly coupled to the
reservoir via fluid conduits, the heat radiator being configured to
dissipate heat from the cooling liquid; a first passage fluidly
coupling the pump chamber and the thermal exchange chamber, wherein
the first passage is configured to direct the cooling liquid from
the outlet of the pump chamber into the thermal exchange chamber
between a first end and a second end of the thermal exchanger
chamber.
25. The cooling system of claim 24, wherein the thermal exchange
chamber includes at least one second passage configured to direct
the cooling liquid out of the thermal exchange chamber, the at
least one second passage is positioned at either a first end or a
second end of the thermal exchange chamber.
26. A liquid cooling system for cooling a heat-generating component
of a computer, comprising: a reservoir configured to circulate a
cooling liquid therethrough, the reservoir including: a pump
chamber housing an impeller and defined at least in part by an
impeller cover and a double-sided chassis, the impeller being
positioned on one side of the chassis and a stator of the pump is
positioned on an opposite side of the chassis; wherein the stator
further comprises stator windings and the double-sided chassis
shields the stator windings from the cooling liquid in the pump
chamber; a thermal exchange chamber disposed between the pump
chamber and the heat-generating component when the system is
installed on the heat-generating component; a heat-exchanging
interface forming a boundary wall of the thermal exchange chamber,
the heat-exchanging interface has an outer surface configured to be
placed in thermal contact with a surface of the heat-generating
component and an inner surface that defines a plurality of channels
that direct the flow of a cooling liquid within the thermal
exchange chamber; a heat radiator adapted to pass the cooling
liquid therethrough, the heat radiator being fluidly coupled to the
reservoir via fluid conduits, the heat radiator being configured to
dissipate heat from the cooling liquid; wherein the pump chamber
further includes: an inlet defined by the impeller cover positioned
below a center of the impeller configured to enable the cooling
liquid to flow into the center of the pump chamber; an outlet
defined by the impeller cover positioned tangentially to the
circumference of the impeller.
27. A liquid cooling system for cooling a heat-generating component
of a computer, comprising: a reservoir configured to circulate a
cooling liquid therethrough, the reservoir including: a pump
chamber housing an impeller and defined at least in part by an
impeller cover and a double-sided chassis, the impeller being
positioned on one side of the chassis and a stator of the pump is
positioned on an opposite side of the chassis, wherein the stator
further comprises stator windings and the double-sided chassis
shields the stator windings from the cooling liquid in the pump
chamber; wherein the pump chamber includes: an inlet defined by the
impeller cover positioned below a center of the impeller configured
to enable a cooling liquid to flow into the center of the pump
chamber; an outlet defined by the impeller cover positioned
tangentially to the circumference of the impeller; a thermal
exchange chamber configured to be disposed between the pump chamber
and a heat-generating component when the system is installed on a
heat-generating component; a heat-exchanging interface forming a
boundary wall of the thermal exchange chamber, the heat-exchanging
interface has an outer surface configured to be placed in thermal
contact with a surface of a heat-generating component and an inner
surface that defines a plurality of channels that direct the flow
of the cooling liquid within the thermal exchange chamber; a heat
radiator adapted to pass the cooling liquid therethrough, the heat
radiator being fluidly coupled to the reservoir via fluid conduits,
the heat radiator being configured to dissipate heat from the
cooling liquid; a first passage fluidly coupling the pump chamber
and the thermal exchange chamber, wherein the first passage is
configured to direct the cooling liquid from the outlet of the pump
chamber into the thermal exchange chamber between a first end and a
second end of the thermal exchanger chamber.
28. A cooling system for a heat-generating component, comprising: a
double-sided chassis adapted to mount a pump configured to
circulate a cooling liquid, the pump comprising a stator and an
impeller, the impeller being positioned on the underside of the
chassis and the stator being positioned on the upper side of the
chassis, the stator further comprising stator windings isolated
from the cooling liquid; a reservoir adapted to pass the cooling
liquid therethrough, the reservoir including: a pump chamber
including the impeller and formed below the chassis, the pump
chamber being defined by at least an impeller cover having one or
more passages for the cooling liquid to pass through; a thermal
exchange chamber formed below the pump chamber and vertically
spaced apart from the pump chamber; wherein the pump chamber and
the thermal exchange chamber being separate chambers that are
fluidly coupled together by the one or more passages; and a
heat-exchanging interface, the heat-exchanging interface forming a
boundary wall of the thermal exchange chamber, and configured to be
placed in thermal contact with a surface of the heat-generating
component; and a heat radiator fluidly coupled to the reservoir and
configured to dissipate heat from the cooling liquid.
29. The cooling system of claim 28, wherein the heat-exchanging
interface includes a first side and a second side opposite the
first side, and wherein the heat-exchanging interface contacts the
cooling liquid in the thermal exchange chamber on the first side
and the heat-exchanging interface is configured to be in thermal
contact with the surface of the heat-generating component on the
second side.
30. The cooling system of claim 29, wherein the first side of the
heat-exchanging interface includes features that are adapted to
increase heat transfer from the heat-exchanging interface to the
cooling liquid in the thermal exchange chamber.
31. The cooling system of claim 30, wherein the features include at
least one of pins or fins.
32. A cooling system for a computer system, comprising: a
centrifugal pump adapted to circulate a cooling liquid, the pump
including: an impeller exposed to the cooling liquid; and a stator
having stator windings isolated from the cooling liquid; a
reservoir configured to be thermally coupled to a heat-generating
component of the computer system, the reservoir including: a
thermal exchange chamber adapted to be positioned in thermal
contact with the heat-generating component; and a separate pump
chamber vertically spaced part from the thermal exchange chamber
and coupled with the thermal exchange chamber through one or more
passages configured for fluid communication between the pump
chamber and the thermal exchange chamber; wherein at least one of
the one or more passages is offset from a center of the
impeller.
33. The cooling system of claim 32, wherein a top wall of the
reservoir physically separates the impeller from the stator
windings.
34. The cooling system of claim 32, wherein the thermal exchange
chamber includes a heat-exchange interface configured to be placed
in thermal contact with the heat-generating component.
35. The cooling system of claim 32, wherein the fluid passage that
is offset from the center of the impeller is positioned
tangentially to the circumference of the impeller.
36. A cooling system for a heat-generating component, comprising: a
pump adapted to circulate a cooling liquid, the pump including: an
impeller exposed to the cooling liquid; and a stator having stator
windings isolated from the cooling liquid; a reservoir including an
impeller cover; an intermediate member and a heat exchange
interface; and a liquid-to-air heat exchanger fluidly coupled to
the reservoir using flexible conduits, the heat exchanger being
configured to be positioned remote from the reservoir; wherein a
top wall of the reservoir and the impeller cover define a pump
chamber for housing the impeller; wherein the intermediate member
and the heat exchange interface define a thermal exchange chamber,
the pump chamber and the thermal exchange chamber being spaced
apart from each other in a vertical direction and fluidly coupled
together; wherein a first side of the heat-exchanging interface is
in contact with a cooling liquid in the thermal exchange chamber
and a second side of the heat-exchanging interface opposite the
first side is configured to be placed in thermal contact with a
surface of the heat-generating component.
37. The cooling system of claim 36, wherein the impeller cover
includes a first opening radially offset from a center of the
impeller and the intermediate member includes a second passage that
is aligned with the first opening, the first and the second opening
being configured to direct the cooling liquid from the pump chamber
into the thermal exchange chamber.
38. The cooling system of claim 36, wherein the first side of the
heat-exchanging interface includes at least one of pins or
fins.
39. The cooling system of claim 36, wherein the top wall of the
reservoir extends between the stator and the impeller and shields
the stator windings from the cooling liquid in the reservoir.
Description
[0001] This application is a continuation of U.S. application Ser.
No. 15/991,384, filed May 29, 2018, which is a continuation of U.S.
application Ser. No. 15/626,706, filed Jun. 19, 2017 (issued Sep.
18, 2018 as U.S. Pat. No. 10,078,355 B2), which is a continuation
of U.S. application Ser. No. 13/861,593, filed Apr. 12, 2013
(issued Aug. 15, 2017 as U.S. Pat. No. 9,733,681 B2), which is a
continuation of U.S. application Ser. No. 11/919,974, filed Jan. 6,
2009, which is a U.S. National Stage Application of
PCT/DK2005/000310, filed May 6, 2005, all of which are incorporated
herein by reference in their entirety.
BACKGROUND
[0002] The present invention relates to a cooling system for a
central processing unit (CPU) or other processing unit of a
computer system. More specifically, the invention relates to a
liquid-cooling system for a mainstream computer system such as a
PC.
[0003] During operation of a computer, the heat created inside the
CPU or other processing unit must be carried away fast and
efficiently, keeping the temperature within the design range
specified by the manufacturer. As an example of cooling systems,
various CPU cooling methods exist and the most used CPU cooling
method to date has been an air-cooling arrangement, wherein a heat
sink in thermal contact with the CPU transports the heat away from
the CPU and as an option a fan mounted on top of the heat sink
functions as an air fan for removing the heat from the heat sink by
blowing air through segments of the heat sink. This air-cooling
arrangement is sufficient as long as the heat produced by the CPU
is kept at today's level, however it becomes less useful in future
cooling arrangements when considering the development of CPUs since
the speed of a CPU is said to double perhaps every 18 months, thus
increasing the heat production accordingly.
[0004] Another design used today is a CPU cooling arrangement where
cooling liquid is used to cool the CPU by circulating a cooling
liquid inside a closed system by means of a pumping unit, and where
the closed system also comprises a heat exchanger past which the
cooling liquid is circulated.
[0005] A liquid-cooling arrangement is more efficient than an
air-cooling arrangement and tends to lower the noise level of the
cooling arrangement in general. However, the liquid-cooling design
consists of many components, which increases the total installation
time, thus making it less desirable as a mainstream solution. With
a trend of producing smaller and more compact PCs for the
end-users, the greater amount of components in a typical
liquid-cooling arrangement is also undesirable. Furthermore, the
many components having to be coupled together incurs a risk of
leakage of cooling liquid from the system.
SUMMARY
[0006] It may be one object of the invention to provide a small and
compact liquid-cooling solution, which is more efficient than
existing air-cooling arrangements and which can be produced at a
low cost enabling high production volumes. It may be another object
to create a liquid-cooling arrangement, which is easy-to-use and
implement, and which requires a low level of maintenance or no
maintenance at all. It may be still another object of the present
invention to create a liquid-cooling arrangement, which can be used
with existing CPU types, and which can be used in existing computer
systems.
[0007] This object may be obtained by a cooling system for a
computer system, said computer system comprising: at least one unit
such as a central processing unit (CPU) generating thermal energy
and said cooling system intended for cooling the at least one
processing unit, a reservoir having an amount of cooling liquid,
said cooling liquid intended for accumulating and transferring of
thermal energy dissipated from the processing unit to the cooling
liquid, a heat exchanging interface for providing thermal contact
between the processing unit and the cooling liquid for dissipating
heat from the processing unit to the cooling liquid, a pump being
provided as part of an integrate element, said integrate element
comprising the heat exchanging interface, the reservoir and the
pump, said pump intended for pumping the cooling liquid into the
reservoir, through the reservoir and from the reservoir to a heat
radiating means, said heat radiating means intended for radiating
thermal energy from the cooling liquid, dissipated to the cooling
liquid, to surroundings of the heat radiating means.
[0008] By providing an integrate element, it is possible to limit
the number of separate elements of the system. However, there is
actually no need for limiting the number of elements, because often
there is enough space within a cabinet of a computer system to
encompass the different individual elements of the cooling system.
Thus, it is surprisingly that, at all, any attempt is conducted of
integrating some of the elements.
[0009] In possible embodiments according to this aspect of the
invention, the entire pump is placed inside the reservoir with at
least an inlet or an outlet leading to the liquid in the reservoir.
In an alternative embodiment the pump is placed outside the
reservoir in the immediate vicinity of the reservoir and wherein at
least an inlet or an outlet is leading directly to the liquid in
the reservoir. By placing the pump inside the reservoir or in the
immediate vicinity outside the reservoir, the integrity of the
combined reservoir, heat exchanger and pump is obtained, so that
the element is easy to employ in new and existing computer systems,
especially mainstream computer systems.
[0010] In a preferred embodiment, the pumping member of the pump
and a driven part of the motor of the pump, such as a rotor of en
electrical motor, is placed inside the reservoir embedded in the
cooling liquid, and wherein a stationary part of the motor of the
pump, such as a stator of an electrical motor, is placed outside
the reservoir. By having the driven part of the motor placed inside
the reservoir submerged in the cooling liquid and the stationary
part of the motor outside the reservoir, there is no need for
encapsulating the stationary part in a liquid-proof insulation.
However, problems may occur having then stationary part driving the
driven part. However, the present invention provide means for
obtaining such action, although not at all evident how to solve
this problem.
[0011] The object may also be obtained by a cooling system for a
computer system, said computer system comprising: at least one unit
such as a central processing unit (CPU) generating thermal energy
and said cooling system intended for cooling the at least one
processing unit, a reservoir having an amount of cooling liquid,
said cooling liquid intended for accumulating and transferring of
thermal energy dissipated from the processing unit to the cooling
liquid, a heat exchanging interface for providing thermal contact
between the processing unit and the cooling liquid for dissipating
heat from the processing unit to the cooling liquid, a pump
intended for pumping the cooling liquid into the reservoir, through
the reservoir and from the reservoir to a heat radiating means,
said cooling system being intended for thermal contact with the
processing unit by means of existing fastening means associated
with the processing unit, and said heat radiating means intended
for radiating from the cooling liquid thermal energy, dissipated to
the cooling liquid, to surroundings of the heat radiating
means.
[0012] The use of existing fastening means has the advantage that
fitting of the cooling system is fast and easy. However, once again
there is no problem for the person skilled in the art to adopt
specially adapted mounting means for any element of the cooling
system, because there are numerous possibilities in existing
cabinets of computer systems for mounting any kind of any number of
elements, also elements of a cooling system.
[0013] In preferred embodiments according to this aspect of the
invention, the existing fastening means are means intended for
attaching a heat sink to the processing unit, or the existing
fastening means are means intended for attaching a cooling fan to
the processing unit, or the existing fastening means are means
intended for attaching a heat sink together with a cooling fan to
the processing unit. Existing fastening means of the kind mentioned
is commonly used for air cooling of CPUs of computer systems,
however, air cooling arrangements being much less complex than
liquid cooling systems. Nevertheless, it has ingeniously been
possible to develop a complex and effective liquid cooling system
capable of utilising such existing fastening means for simple and
less effective air cooling arrangements.
[0014] According to an aspect of the invention, the pump is
selected from the following types: Bellows pump, centrifugal pump,
diaphragm pump, drum pump, flexible liner pump, flexible impeller
pump, gear pump, peristaltic tubing pump, piston pump, processing
cavity pump, pressure washer pump, rotary lobe pump, rotary vane
pump and electro-kinetic pump. By adopting one or more of the
solution of the present invention, a wide variety of pumps may be
used without departing from the scope of the invention.
[0015] According to another aspect of the invention, driving means
for driving the pump is selected among the following driving means:
electrically operated rotary motor, piezo-electrically operated
motor, permanent magnet operated motor, fluid-operated motor,
capacitor-operated motor. As is the case when selecting the pump to
pump the liquid, by adopting one or more of the solution of the
present invention, a wide variety of pumps may be used without
departing from the scope of the invention.
[0016] The object may also be obtained by a cooling system for a
computer system, said computer system comprising: at least one unit
such as a central processing unit (CPU) generating thermal energy
and said cooling system intended for cooling the at least one
processing unit, a reservoir having an amount of cooling liquid,
said cooling liquid intended for accumulating and transferring of
thermal energy dissipated from the processing unit to the cooling
liquid, a heat exchanging interface for providing thermal contact
between the processing unit and the cooling liquid for dissipating
heat from the processing unit to the cooling liquid, a pump
intended for pumping the cooling liquid into the reservoir, through
the reservoir and from the reservoir to a heat radiating means, and
said cooling system further comprising a pump wherein the pump is
driven by an AC electrical motor by a DC electrical power supply of
the computer system, where at least part of the electrical power
from said power supply is intended for being converted to AC being
supplied to the electrical motor.
[0017] It may be advantageous to use an AC motor, such as a 12V AC
motor, for driving the pump in order to obtain a stabile unit
perhaps having to operate 24 hours a day, 365 days a year. However,
the person skilled in the art will find it unnecessary to adopt as
example a 12V motor because high voltage such as 220V or 110V is
readily accessible as this is the electrical voltage used to power
the voltage supply of the computer system itself. Although choosing
to use a 12V motor for the pump, it has never been and will never
be the choice of the person skilled in the art to use an AC motor.
The voltage supplied by the voltage supply of the computer system
itself is DC, thus this will be the type of voltage chosen by the
skilled person.
[0018] In preferred embodiments according to any aspect of the
invention, an electrical motor is intended both for driving the
pump for pumping the liquid and for driving the a fan for
establishing a flow of air in the vicinity of the reservoir, or an
electrical motor is intended both for driving the pump for pumping
the liquid and for driving the a fan for establishing a flow of air
in the vicinity of the heat radiating means, or an electrical motor
is intended both for driving the pump for pumping the liquid, and
for driving the a fan for establishing a flow of air in the
vicinity of the reservoir, and for driving the a fan for
establishing a flow of air in the vicinity of the heat radiating
means.
[0019] By utilising a single electrical motor for driving more than
one element of the cooling system according to any of the aspects
of the invention, the lesser complexity and the reliability of the
cooling system will be further enhanced.
[0020] The heat exchanging interface may be an element being
separate from the reservoir, and where the heat exchanging
interface is secured to the reservoir in a manner so that the heat
exchanging interface constitutes part of the reservoir when being
secured to the reservoir. Alternatively, the heat exchanging
interface constitutes an integrate surface of the reservoir, and
where the heat exchanging surface extends along an area of the
surface of the reservoir, said area of surface being intended for
facing the processing unit and said area of surface being intended
for the close thermal contact with the processing unit. Even
alternatively, the heat exchanging interface is constitutes by a
free surface of the processing unit, and where the free surface is
capable of establishing heat dissipation between the processing
unit and the cooling liquid through an aperture provided in the
reservoir, and where the aperture extends along an area of the
surface of the reservoir, said surface being intended for facing
the processing unit.
[0021] Possibly, an uneven surface such as pins or fins extending
from the copper plate provide a network of channels across the
inner surface of the heat exchanging interface. A network of
channels ensure the cooling liquid being passed along the inner
surface of the interface such as a copper plate in a way that
maximises the retention time of the cooling liquid along the heat
exchanging interface and in a way that optimises the thermal
exchange between the heat exchanging interface and the cooling
liquid as long as the cooling liquid is in thermal contact with
heat exchanging interface.
[0022] Possibly, the cooling system may be provided with a heat
exchanging interface for providing thermal contact between the
processing unit and the cooling liquid for dissipating heat from
the processing unit to the cooling liquid, a pumping means being
intended for pumping the cooling liquid into the reservoir, through
the reservoir and from the reservoir to a heat radiating means,
said heat radiating means intended for radiating thermal energy
from the cooling liquid, dissipated to the cooling liquid, to
surroundings of the heat radiating means, said heat exchanging
interface constituting a heat exchanging surface being manufactured
from a material suitable for heat conducting, and with a first side
of the heat exchanging surface facing the central processing unit
being substantially plane and with a second side of the heat
exchanging surface facing the cooling liquid being substantially
plane and said reservoir being manufactured from plastic, and
channels or segments being provided in the reservoir for
establishing a certain flow-path for the cooling liquid through the
reservoir.
[0023] Providing a plane heat exchanging surface, both the first,
inner side being in thermal contact with the cooling liquid and the
second, outer side being in thermal contact with the heat
generating processing unit, results in the costs for manufacturing
the heat exchanging surface is reduced to an absolute minimum.
[0024] According to the above possible solution, an inlet of the
pumping means is positioned in immediate vicinity of the heat
exchanging interface for thereby obtaining a turbulence of flow of
the cooling liquid in the immediate vicinity of the heat exchanging
interface. The turbulence of flow is advantageous for obtaining a
heat dissipation. If the heat exchanging interface is plane, the
inlet of the pump being positioned as mentioned above, may result
in a turbulence of flow occurring along the heat exchanging
interface, at least in the vicinity of the inlet of the pump, but
possibly also distant form the inlet.
[0025] Alternatively, or additionally, an outlet of said pumping
means being positioned in immediate vicinity of the heat exchanging
interface for thereby obtaining a turbulence of flow of the cooling
liquid in the immediate vicinity of the heat exchange interface.
The turbulence of flow is advantageous for obtaining a heat
dissipation. If the heat exchanging interface is plane, the inlet
of the pump being positioned as mentioned above, may result in a
turbulence of flow occurring along the heat exchanging interface,
at least in the vicinity of the inlet of the pump, but possibly
also distant form the inlet.
[0026] However, a plane first, inner surface may also result in the
cooling liquid passing the heat exchanging surface too fast. This
may be remedied by providing grooves along the inner surface,
thereby providing a flow path in the heat exchanging surface. This
however results in the costs for manufacturing the heat exchanging
surface increasing.
[0027] The solution to this problem has been dealt with by
providing channels or segments in the reservoir housing in stead.
The reservoir housing may be manufactured by injection moulding or
by casting, depending on the material which the reservoir housing
is made from. Proving channels or segments during moulding or
casting of the reservoir housing is much more cost-effective than
milling grooves along the inner surface of the heat exchanging
surface.
[0028] Possibly, the cooling system may be provided with at least
one liquid reservoir mainly for dissipating or radiating heat, said
heat being accumulated and transferred by said cooling liquid, said
cooling system being adapted such as to provide transfer of said
heat from a heat dissipating surface to a heat radiating surface
where said at least one liquid reservoir being provided with one
aperture intended for being closed by placing said aperture
covering part of, alternatively covering the whole of, the at least
one processing unit in such a way that a free surface of the
processing unit is in direct heat exchanging contact with an
interior of the reservoir, and thus in direct heat exchanging
contact with the cooling liquid in the reservoir, through the
aperture.
[0029] Heat dissipation from the processing unit to the cooling
liquid must be very efficient to ensure proper cooling of the
processing unit, Especially in the case, where the processing unit
is a CPU, the surface for heat dissipation is limited by the
surface area of the CPU. This may be remedied by utilising a heat
exchanging surface being made of a material having a high thermal
conductivity such as copper or aluminium and ensuring a proper
thermal bondage between the heat exchanging interface and the
CPU.
[0030] However, in a possible embodiment according to the features
in the above paragraph, the heat dissipation takes place directly
between the processing unit and the cooling liquid by providing an
aperture in the reservoir housing, said aperture being adapted for
taking up a free surface of the processing unit. Thereby, the free
surface of the processing unit extends into the reservoir or
constitutes a part of the boundaries of the reservoir, and the
cooling liquid has direct access to the free surface of the
processing unit.
[0031] A possible heat exchanging interface may be the direct
contact between the heat generating unit such as a CPU and the
cooling liquid, where at least one unit such as a central
processing unit (CPU) generating thermal energy and said cooling
system intended for cooling the at least one processing unit
comprising at least one liquid reservoir mainly for dissipating or
radiating heat, said heat being accumulated and transferred by said
cooling liquid, said cooling system being adapted such as to
provide transfer of said heat from a heat dissipating interface to
a heat radiating surface where said at least one liquid reservoir
being provided with one aperture intended for being closed by
placing said aperture covering part of, alternatively covering the
whole of, the at least one processing unit in such a way that a
free surface of the processing unit is in direct heat exchanging
contact with an interior of the reservoir, and thus in direct heat
exchanging contact with the cooling liquid in the reservoir,
through the aperture.
[0032] The aperture of the reservoir may be intended for being
closed by attaching boundaries of said aperture to a free surface
of a the processing unit, said boundaries being liquid-proof when
attached to the free surface of the processing unit so that the
liquid may flow freely across the free surface without the risk of
the liquid dissipating through the boundaries. Alternatively, but
posing the same technical effect, the aperture of the reservoir is
intended for being closed by attaching boundaries of said aperture
along boundaries of a free surface of the processing unit.
[0033] If a heat sink is provided as an aid in dissipating heat
from the heat generating unit such as a CPU, the aperture of the
reservoir may be intended for being closed by attaching boundaries
of said aperture to a free surface of a heat sink. Alternatively,
the aperture of the reservoir may be intended for being closed by
attaching boundaries of said aperture along boundaries of a free
surface of a heat sink. Alternatively, possibly, the heat
exchanging interface may be provided as a first reservoir intended
for being closed by attaching boundaries of an aperture in the
first reservoir to, alternatively along, a free surface of a said
processing unit, and a second reservoir intended for being closed
by attaching boundaries of an aperture in the second reservoir to,
alternatively along, a free surface of a to a free surface of a
heat sink, and liquid conducting means provided between the first
reservoir and the second reservoir.
[0034] The first reservoir may be closed by attaching said first
reservoir to a heat exchanging surface element being in close
thermal contact with the processing unit, said heat exchanging
surface intended for dissipating heat from the processing unit to
cooling liquid in the first reservoir, and wherein a second
reservoir is closed by attaching said second reservoir to a surface
of a heat sink, said heat sink intended for radiating heat from
cooling liquid in the second reservoir to the exterior
surroundings.
[0035] Also, the first reservoir and said second reservoir may be
provided as a monolithic structure comprising both the first
reservoir and the second reservoir and where both a heat
dissipation from the processing unit to the cooling liquid in the
first reservoir and heat radiation from the cooling liquid in the
second reservoir to exterior surrounding is provided by the
monolithic structure. The said monolithic structure may preferably
be manufactured at least partly from plastic, preferably being
manufactured fully in plastic, and said monolithic structure thus
being manufactured by injection moulding.
[0036] Transfer of said cooling liquid from an outlet of the first
reservoir to an inlet of the second reservoir, and from an outlet
of the second reservoir to an inlet of the first reservoir, and
circulating the cooling liquid within said liquid conducting means
is provided by a pumping means being intended for pumping the
cooling liquid. One of said reservoirs of said monolithic structure
may comprise said pumping means.
[0037] An inlet and/or an outlet and/or a pumping member of said
pumping means, may be provided in the vicinity of said
substantially plane side in order to provide a turbulence of flow
and hereby improve the exchange of heat between said cooling liquid
and substantially plane side, and the inlet of the pumping means
may be provided within the first reservoir and the outlet may be
provided within the second reservoir.
[0038] According to one aspect of the invention, a method is
envisaged, said method of cooling a computer system comprising at
least one unit such as a central processing unit (CPU) generating
thermal energy and said method utilising a cooling system for
cooling the at least one processing unit and, said cooling system
comprising a reservoir, at least one heat exchanging interface and
a pumping means, said method of cooling comprising the steps of
establishing, or defining, or selecting an operative status of the
pumping means controlling the operation of the motor of the pumping
means in response to the following parameters; the necessary
direction of movement for obtaining a pumping action of a pumping
member of the pumping means, the possible direction of movement of
a driving part of the motor of the pumping means, and in accordance
with the operative status being established, defined or selected,
controlling the operation of the computer system in order to
achieve the necessary direction of movement of the driving part of
the motor for establishing the necessary direction of movement for
obtaining he pumping action of the pumping member.
[0039] There may be pumping means, where the pumping member is only
operationable in one direction but where the motor driving the
pumping member is operationable in two directions. The solution to
this problem is to either choose a pumping member operationable in
both directions or to chose a motor being operationable in only one
direction. According to the invention, a solution is provided where
a one-way directional pumping member may be operated any a two-way
directional motor. Despite the contradictory nature of this
solution, advantages may however be present.
[0040] As example, the method is being applied to a cooling system
where the pumping member is a rotary impeller having a one-way
direction for obtaining a pumping action, and where the motor of
the pumping means is an electrical AC motor having a rotor
constituting the driving part of the motor, and where said method
comprises the step of establishing, or defining, or selecting a
rotary position of the rotor of the electrical AC motor, and
applying at least one half-wave of an AC power signal to the stator
of the AC motor before applying a full-wave AC power signal.
[0041] As an alternative example, the method is being applied to a
cooling system where the pumping member is a rotary impeller having
a one-way direction for obtaining a pumping action, and where the
motor of the pumping means is an electrical AC motor having a rotor
constituting the driving part of the motor, and said method
comprises the step of establishing, or defining, or selecting a
rotary position of the rotor of the electrical AC motor, and
applying at least one half-wave of an AC power signal to the stator
of the AC motor after having applied the full-wave AC power
signal.
[0042] In both the above examples, the advantages of the one-way
impeller from a traditional DC pump together with the advantages of
a motor from a traditional AC pump is obtained in the solution
mentioned. The performance of an impeller of a DC pump is much
better than the performance of an impeller from an AC pump. The
motor from an AC pump is more reliable than a motor from a DC pump.
The advantageous obtained is thus of synergetic nature, seeing that
different advantages of the impeller of the DC pump and of the
motor of the AC pump are different in nature.
[0043] According to another aspect of the invention, a method is
envisaged, said method of cooling a computer system comprising at
least one unit such as a central processing unit (CPU) generating
thermal energy and said method utilising a cooling system for
cooling the at least one processing unit and, said cooling system
comprising a reservoir, at least one heat exchanging interface, an
air blowing fan, a pumping means, said method of cooling comprising
the steps of applying one of the following possibilities of how to
operate the computer system: establishing, or defining, or
selecting an operative status of the computer system controlling
the operation of at least one of the following means of the
computer system; the pumping means and the air blowing fan in
response to at least one of the following parameters; a surface
temperature of the heat generating processing unit, an internal
temperature of the heat generating processing unit, or a processing
load of the CPU and in accordance with the operative status being
established, defined or selected, controlling the operation of the
computer system in order to achieve at least one of the following
conditions; a certain cooling performance of the cooling system, a
certain electrical consumption of the cooling system, a certain
noise level of the cooling system.
[0044] Applying the above method ensures an operation of the
computer system being in accordance with selected properties during
the use of the computer system. For some applications, the cooling
performance is vital such as may be the case when working with
image files or when downloading large files from a network during
which the processing units is highly loaded and thus generating
much heat. For other applications, the electrical power consumption
is more vital such as may be the case when utilising domestic
computer systems or in large office building in environments where
the electrical grid may be weak such as in third countries. In
still other applications, the noise generated by the cooling system
is to be reduced to a certain level, which may be the case in
office buildings with white collar people working alone, or at
home, if the domestic computer perhaps is situated in the living
room, or at any other location where other exterior considerations
have to be dealt with.
[0045] According to another aspect of the invention, a method is
envisaged, said method being employed with cooling system further
comprising a pumping means with an impeller for pumping the cooling
liquid through a pumping housing, said pumping means being driven
by an AC electrical motor with a stator and a rotor, and said
pumping means being provided with a means for sensing a position of
the rotor, and wherein the method comprises the following steps:
initially establishing a preferred rotational direction of the
rotor of the electrical motor before start of the electrical motor,
sensing the angular position of the rotor during start, applying an
electrical AC voltage to the electrical motor and selecting the
signal value, positive or negative, of the AC voltage at start of
the electrical motor said selection being made according to the
preferred rotational direction, and said application of the AC
signal, such as an AC voltage, being performed by the computer
system for applying the AC signal, such as an AC voltage, from the
electrical power supply of the computer system during conversions
of the electrical DC signal, such as a DC voltage, of the power
supply to the AC signal, such as an AC voltage, for the electrical
motor.
[0046] Adopting the above method according to the invention ensures
the most efficient circulation of cooling liquid in the cooling
system and at the same time ensures the lowest possible energy
consumption of the electrical motor driving the impeller. The
efficient circulation of the cooling liquid is obtained by means of
an impeller being designed for rotation in one rotational direction
only, thus optimising the impeller design with regard to the only
one rotational direction as opposed to both rotational directions.
The low energy consumption is achieved because of the impeller
design being optimised, thus limiting the necessary rotational
speed of the impeller for obtaining e certain amount of flow of the
cooling liquid through the cooling system. A bonus effect of the
lowest possible energy consumption being obtained is the lowest
possible noise level of the pump also being obtained. The noise
level of the pump is amongst other parameters also dependent on the
design and the rotational speed of the impeller. Thus, an optimised
impeller design and impeller speed will reduce the noise level to
the lowest possible in consideration of ensuring a certain cooling
capacity.
BRIEF DESCRIPTION OF THE FIGURES
[0047] The invention will hereafter be described with reference to
the drawings, where
[0048] FIG. 1 shows an embodiment of the prior art. The figure
shows the typical components in an air-cooling type CPU cooling
arrangement.
[0049] FIG. 2 shows an embodiment of the prior art. The figure
shows the parts of the typical air-cooling type CPU cooling
arrangement of FIG. 1 when assembled.
[0050] FIG. 3 shows an embodiment of the prior art. The figure
shows the typical components in a liquid-cooling type CPU cooling
arrangement.
[0051] FIG. 4 is an exploded view of the invention and the
surrounding elements.
[0052] FIG. 5 shows the parts shown in the previous figure when
assembled and attached to the motherboard of a computer system.
[0053] FIG. 6 is an exploded view of the reservoir from the
previous FIGS. 4 and 5 seen from the opposite site and also showing
the pump.
[0054] FIG. 7 is a cut-out view into the reservoir housing the pump
and an inlet and an outlet extending out of the reservoir.
[0055] FIG. 8 is a view of the cooling system showing the reservoir
connected to the heat radiator.
[0056] FIG. 9-10 are perspective views of a possible embodiment of
reservoir housing providing direct contact between a CPU and a
cooling liquid in a reservoir.
[0057] FIG. 11-13 are perspective views of a possible embodiment of
heat sink and a reservoir housing constituting an integrated
unit.
[0058] FIG. 14 is a perspective view of the embodiment shown in
FIG. 9-10 and the embodiment shown in FIG. 11-13 all together
constituting an integrated unit.
[0059] FIG. 15-16 are perspective view of a possible embodiment of
a reservoir and a pump and a heat exchanging surface constituting
an integrated unit
[0060] FIG. 17 is a perspective view of a preferred embodiment of a
reservoir and a pump and a heat exchanging surface constituting an
integrated unit,
[0061] FIG. 18 is a plane view of a possible, however preferred
embodiment of an AC electrical motor for a pumping means of the
cooling system according to the invention, and
[0062] FIG. 19 is a graph showing a method for starting a rotor of
the electrical AC motor, said AC motor driving an impeller selected
from a pump driven by a DC motor.
[0063] FIG. 20 is a simplified schematic showing a cross-sectional
view of the reservoir along plane 20-20 of FIG. 17.
DETAILED DESCRIPTION
[0064] FIG. 1 is an exploded view of an embodiment of prior art
cooling apparatus for a computer system. The figure shows the
typical components in an air-cooling type CPU cooling arrangement.
The figure shows a prior art heat sink 94 intended for air cooling
and provided with segments intersected by interstices, a prior art
air fan 5 which is to be mounted on top of the heat sink by use of
fastening means 3 and 6.
[0065] The fastening means comprises a frame 3 provided with holes
intended for bolts, screws, rivets or other suitable fastening
means (not shown) for thereby attaching the frame to a motherboard
2 of a CPU 1 or onto another processing unit of the computer
system. The frame 3 is also provided with mortises provided in
perpendicular extending studs in each corner of the frame, said
mortises intended for taking up tenons of a couple of braces. The
braces 6 are intended for enclosing the heat sink 94 and the air
fan 5 so that the air fan and the heat sink thereby is secured to
the frame. Using proper retention mechanisms, when the frame is
attached to the motherboard of the CPU of other processing unit,
and when the tenons of the braces are inserted into the mortises of
the frame, the air fan and heat exchanger is pressed towards the
CPU by using a force perpendicular to the CPU surface, said force
being provided by lever arms.
[0066] FIG. 2 shows the parts of the typical air-cooling type CPU
cooling arrangement of FIG. 1, when assembled. The parts are
attached to each other and will be mounted on top of a CPU on a
motherboard (not shown) of a computer system.
[0067] FIG. 3 shows another embodiment of a prior art cooling
system. The figure shows the typical components in a liquid-cooling
type CPU cooling arrangement. The figure shows a prior art heat
exchanger 7, which is in connection with a prior art liquid
reservoir 8, a prior art liquid pump 9 and a heat radiator 11 and
an air fan 10 provided together with the heat radiator. The prior
art heat exchanger 7, which can be mounted on a CPU (not shown) is
connected to a radiator and reservoir, respectively. The reservoir
serves as a storage unit for excess liquid not capable of being
contained in the remaining components. The reservoir is also
intended as a means for venting the system of any air entrapped in
the system and as a means for filling the system with liquid. The
heat radiator 11 serves as a means for removing the heat from the
liquid by means of the air fan 10 blowing air through the heat
radiator. All the components are in connection with each other via
tubes for conducting the liquid serving as the cooling medium.
[0068] FIG. 4 is an exploded view of a cooling system according to
an embodiment of the invention. Also elements not being part of the
cooling system as such are shown. The figure shows a central
processing unit CPU 1 mounted on a motherboard of a computer system
2. The figure also shows a part of the existing fastening means,
i.e. amongst others the frame 3 with mortises provided in the
perpendicular extending studs in each corner of the frame. The
existing fastening means, i.e. the frame 3 and the braces 6, will
during use be attached to the motherboard 2 by means of bolts,
screws, rivets or other suitable fastening means extending through
the four holes provided in each corner of the frame and extending
through corresponding holes in the motherboard of the CPU. The
frame 3 will still provide an opening for the CPU to enable the CPU
to extend through the frame.
[0069] The heat exchanging interface 4 is a separate element and is
made of a heat conducting material having a relative high heat
thermal conductivity such as copper or aluminium, and which will be
in thermal contact with the CPU 1, when the cooling system is
fastened to the motherboard 2 of the CPU. The heat exchanging
surface constitutes part of a liquid reservoir housing 14, thus the
heat exchanger 4 constitutes the part of the liquid reservoir
housing facing the CPU. The reservoir may as example be made of
plastic or of metal. The reservoir or any other parts of the
cooling system, which are possibly manufactured from a plastic
material may be "metallised" in order to minimise liquid diffusion
or evaporation of the liquid. The metal may be provided as a thin
layer of metal coating provided on either or on both of the
internal side or the external side of the plastic part.
[0070] If the reservoir is made of metal or any other material
having a relative high heat conductivity compared to as example
plastic, the heat exchanging interface as a separate element may be
excluded because the reservoir itself may constitute a heat
exchanger over an area, wherein the reservoir is in thermal contact
with the processing unit. Alternatively to having the heat
exchanging interface constitute part of the liquid reservoir
housing, the liquid reservoir housing may be tightly attached to
the heat exchanging interface by means of screws, glue, soldering,
brazing or the like means for securing the heat exchanging
interface to the housing and vice versa, perhaps with a sealant 5
provided between the housing and the heat exchanging interface.
[0071] Alternatively to providing a heat exchanging interface
integrate with the reservoir containing the cooling liquid, it will
be possible to exclude the heat exchanger and providing another
means for dissipating heat from the processing unit to the cooling
liquid in the reservoir, The other means will be a hole provided in
the reservoir, said hole intended for being directed towards the
processing unit. Boundaries of the hole will be sealed towards
boundaries of the processing unit or will be sealed on top of the
processing unit for thereby preventing cooling liquid from the
reservoir from leaking. The only prerequisite to the sealing is
that a liquid-tight connection is provided between boundaries of
the hole and the processing unit or surrounding of the processing
unit, such as a carrier card of the processing unit.
[0072] By excluding the heat exchanger, a more effective heat
dissipation will be provided from the processing unit and to the
cooling liquid of the reservoir, because the intermediate element
of a heat exchanger is eliminated. The only obstacle in this sense
is the provision of a sealing being fluid-tight in so that the
cooling liquid in the reservoir is prevented from leaking.
[0073] The heat exchanging surface 4 is normally a copper plate.
When excluding the heat exchanging surface 4, which may be a
possibility not only for the embodiments shown in FIG. 4, but for
all the embodiments of the invention, it may be necessary to
provide the CPU with a resistant surface that will prevent
evaporation of the cooling liquid and/or any damaging effect that
the cooling liquid may pose to the CPU. A resistant surface may be
provided the CPU from the CPU producer or it may be applied
afterwards. A resistant surface to be applied afterwards may e.g.
be a layer, such as an adhesive tape provided on the CPU. The
adhesive tape may be made with a thin metal layer e.g. in order to
prevent evaporation of the cooling liquid and/or any degeneration
of the CPU itself.
[0074] Within the liquid reservoir, a liquid pump (not shown) is
placed for pumping a cooling liquid from an inlet tube 15
connection being attached to the housing of the reservoir through
the reservoir and past the heat exchanger in thermal contact with
the CPU to an outlet tube connection 16 also being attached to the
reservoir housing. The existing fastening means comprising braces 6
with four tenons and the frame 3 with four corresponding mortises
will fasten the reservoir and the heat exchanger to the motherboard
of the CPU. When fastening the two parts of the existing fastening
means to each other the fastening will by means of the lever arms
18 create a force to assure thermal contact between the CPU 1
mounted on the motherboard and the heat exchanger 4 being provided
facing the CPU.
[0075] The cooling liquid of the cooling system may be any type of
cooling liquid such as water, water with additives such as
anti-fungicide, water with additives for improving heat conducting
or other special compositions of cooling liquids such as
electrically non-conductive liquids or liquids with lubricant
additives or anti-corrosive additives.
[0076] FIG. 5 shows the parts shown in FIG. 4 when assembled and
attached to the motherboard of a CPU of a computer system 2. The
heat exchanger and the CPU is in close thermal contact with each
other. The heat exchanger and the remainder of the reservoir
housing 14 is fastened to the motherboard 2 by means of the
existing fastening means being secured to the motherboard of the
CPU and by means of the force established by the lever arms 18 of
the existing fastening means. The tube inlet connection 15 and the
tube outlet connection 16 are situated so as to enable connection
of tubes to the connections.
[0077] FIG. 6 is an exploded view of the reservoir shown in
previous FIG. 4 and FIG. 5 and seen from the opposite site and also
showing the pump 21 being situated inside the reservoir. Eight
screws 22 are provided for attaching the heat exchanging surface 4
to the remainder of the reservoir. The heat exchanging surface is
preferably made from a copper plate having a plane outer surface as
shown in the figure, said outer surface being intended for abutting
the free surface of the heat generating component such as the CPU
(see FIG. 4). However, also the inner surface (not shown, see FIG.
7) facing the reservoir is plane. Accordingly, the copper plate
need no machining other than the shaping of the outer boundaries
into the octagonal shape used in the embodiment shown and drilling
of holes for insertion of the bolts. No milling of the inner and/or
the outer surface need be provided.
[0078] A sealant in form of a gasket 13 is used for the connection
between the reservoir housing 14 and the heat exchanging surface
forming a liquid tight connection. The pump is intended for being
placed within the reservoir. The pump has a pump inlet 20 through
which the cooling liquid flows from the reservoir and into the
pump, and the pump has a pump outlet 19 through which the cooling
liquid is pumped from the pump and to the outlet connection. The
figure also shows a lid 17 for the reservoir. The non-smooth inner
walls of the reservoir and the fact that the pump is situated
inside the reservoir will provide a swirling of the cooling liquid
inside the reservoir.
[0079] However, apart from the non-smooth walls of the reservoir
and the pump being situated inside the reservoir, the reservoir may
be provided with channels or segments for establishing a certain
flow-path for the cooling liquid through the reservoir (see FIG.
9-10 and FIG. 15). Channel or segments are especially needed when
the inner surface of the heat exchanging surface is plane and/or
when the inner walls of the reservoir are smooth and/or if the pump
is not situated inside the reservoir. In either of the
circumstances mentioned, the flow of the cooling liquid inside the
reservoir may result in the cooling liquid passing the reservoir
too quickly and not being resident in the reservoir for a
sufficient amount of time to take up a sufficient amount of heat
from the heat exchanging surface. By providing channels or segments
inside the reservoir, a flow will be provided forcing the cooling
liquid to pass the heat exchanging surface, and the amount of time
increased of the cooling liquid being resident inside the
reservoir, thus enhancing heat dissipation. If channels or segments
are to be provided inside the reservoir, the shape and of the
channels and segments may be decisive of whether the reservoir is
to be made of plastic, perhaps by injection moulding, or is to be
made of metal such as aluminium, perhaps by die casting.
[0080] The cooling liquid enters the reservoir through the tube
inlet connection 15 and enters the pump inlet 20, and is pumped out
of the pump outlet 19 connected to the outlet connection 16. The
connection between the reservoir and the inlet tube connection and
the outlet tube connection, respectively, are made liquid tight.
The pump may not only be a self-contained pumping device, but may
be made integrated into the reservoir, thus making the reservoir
and a pumping device one single integrated component. This single
integrated element of the reservoir and the pumping device may also
be integrated, thus making the reservoir, the pumping device and
the heat exchanging surface one single integrated unit. This may as
example be possible if the reservoir is made of a metal such as
aluminium. Thus, the choice of material provides the possibility of
constituting both the reservoir and a heat exchanging surface
having a relatively high heat conductivity, and possibly also
renders the possibility of providing bearings and the like
constructional elements for a motor and a pumping wheel being part
of the pumping device.
[0081] In an alternative embodiment, the pump is placed in
immediate vicinity of the reservoir, however outside the reservoir.
By placing the pump outside, but in immediate vicinity of the
reservoir, still an integrate element may be obtained. The pump or
the inlet or the outlet is preferably positioned so as to obtain a
turbulence of flow in the immediate vicinity of the heat exchanging
interface, thereby promoting increased heat dissipation between the
heat exchanging interface end the cooling liquid. even in the
alternative, a pumping member such as an impeller (see FIG. 15-16)
may be provided in the immediate vicinity of the heat exchanging
surface. The pumping member itself normally introduces a turbulence
of flow, and thereby the increased heat dissipation is promoted
irrespective of the position of the pump itself, or the position of
the inlet or of the outlet to the reservoir or to the pump.
[0082] The pump may be driven by an AC or a DC electrical motor.
When driven by an AC electrical motor, although being technically
and electrically unnecessary in a computer system, this may be
accomplished by converting part of the DC electrical power of the
power supply of the computer system to AC electrical power for the
pump. The pump may be driven by an electrical motor at any voltage
common in public electrical networks such as 110V or 220V. However,
in the embodiment shown, the pump is driven by a 12V AC electrical
motor.
[0083] Control of the pump in case the pump is driven by an AC
electrical motor, preferably takes place by means of the operative
system or an alike means of the computer system itself, and where
the computer system comprises means for measuring the CPU load
and/or the CPU temperature. Using the measurement performed by the
operative system or alike system of the computer system eliminates
the need for special means for operating the pump. Communication
between the operative system or alike system and a processor for
operating the pump may take place along already established
communication links in the computer system such as a USB-link.
Thereby, a real-time communication between the cooling system and
the operative system is provided without any special means for
establishing the communication.
[0084] In the case of the motor driving the pump is an AC
electrical motor, the above method of controlling the pump may be
combined with a method, where said pumping means is provided with a
means for sensing a position of the rotor of the electrical motor,
and wherein the following steps are employed: Initially
establishing a preferred rotational direction of the rotor of the
electrical motor, before start of the electrical motor, sensing the
angular position of the rotor, during start, applying an electrical
AC voltage to the electrical motor and selecting the signal value,
positive or negative, of the AC voltage at start of the electrical
motor, said selection being made according to the preferred
rotational direction, and said application of the AC voltage being
performed by the computer system for applying the AC voltage from
the electrical power supply of the computer system during
conversion of the electrical DC voltage of the power supply to AC
voltage for the electrical motor. By the operative system of the
computer system itself generating the AC voltage for the electrical
motor, the rotational direction of the pump is exclusively selected
by the computer system, non-depending on the applied voltage of the
public grid powering the computer system.
[0085] Further control strategies utilising the operative system or
alike system of the computer system may involve balancing the
rotational speed of the pump as a function of the cooling capacity
needed. If a lower cooling capacity is needed, the rotational speed
of the pump, may be limited, thereby limiting the noise generating
by the motor driving the pump.
[0086] In the case an air fan is provided in combination with a
heat sink as shown in FIG. 1, of the air fan is provided in
combination with the heat radiator, the operative system or alike
system of the computer system may be designed for regulating the
rotational speed of the pump, and thus of the motor driving the
pump, and the rotational speed of the air fan, and thus the motor
driving the air fan. The regulation will take into account the
cooling capacity needed, but the regulation will at the same time
take into account which of the two cooling means, i.e. the pump and
the air fan, is generating the most noise. Thus, it the air fan
generally is generating more noise than the pump, then the
regulation will reduce the rotational speed of the air fan before
reducing the rotational speed of the pump, whenever a lower cooling
capacity is needed. Thereby, the noise level of the entire cooling
system is lowered as much as possible. If the opposite is the case,
i.e. the pump generally generating more noise than the air fan,
then the rotational speed of the pump will be reduced before
reducing the rotational speed of the air fan.
[0087] Even further control strategies involve controlling the
cooling capacity in dependence on the type of computer processing
taking place. Some kind of computer processing, such as
word-processing, applies a smaller load on the processing units
such as the CPU than other kinds of computer processing, such as
image processing. Therefore, the kind of processing taking place on
the computer system may be used as an indicator of the cooling
capacity. It may even be possible as part of the operative system
or similar system to establish certain cooling scenarios, depending
on the kind of processing intended by the user. If the user selects
as example word-processing, a certain cooling strategy is applied
based on a limited need for cooling. If the user selects as example
image-processing, a certain cooling strategy is applied based on an
increased need for cooling. Two or more different cooling scenarios
may be established depending on the capacity and the control
possibilities and capabilities of the cooling system and depending
on the intended use of the computer system, either as selected by a
user during use of the computer system or as selected when choosing
hardware during build-up of the computer system, i.e. before actual
use of the computer system.
[0088] The pump is not being restricted to a mechanical device, but
can be in any form capable of pumping the cooling liquid through
the system. However, the pump is preferably one of the following
types of mechanical pumps: Bellows pump, centrifugal pump,
diaphragm pump, drum pump, flexible liner pump, flexible impeller
pump, gear pump, peristaltic tubing pump, piston pump, processing
cavity pump, pressure washer pump, rotary lobe pump, rotary vane
pump and electro-kinetic pump. Similarly, the motor driving the
pumping member need not be electrical but may also be a
piezo-electrically operated motor, a permanent magnet operated
motor, a fluid-operated motor or a capacitor-operated motor. The
choice of pump and the choice of motor driving the pump id
dependent on many different parameters, and it is up to the person
skilled in the art to choose the type of pump and the type of motor
depending on the specific application. As example, some pumps and
some motors are better suited for small computer systems such as
lab-tops, some pumps and some motors are better suited for
establishing i high flow of the cooling liquid and thus a high
cooling effect, and even some pumps and motors are better suited
for ensuring a low-noise operation of the cooling system.
[0089] FIG. 7 is a cut-out view into the reservoir, when the
reservoir and the heat exchanging surface 4 is assembled and the
pump 21 is situated inside the reservoir. The reservoir is provided
with the tube inlet connection (not seen from the figure) through
which the cooling liquid enters the reservoir. Subsequently, the
cooling liquid flows through the reservoir passing the heat
exchanging surface and enters the inlet of the pump. After having
been passed through the pump, the cooling liquid is passed out of
the outlet of the pump and further out through the tube outlet
connection 16. The figure also shows a lid 17 for the reservoir.
The flow of the cooling liquid inside the reservoir and trough the
pump may be further optimised in order to use as little energy as
possible for pumping the cooling liquid, but still having a
sufficient amount of heat from the heat exchanging surface being
dissipated in the cooling liquid. This further optimisation can be
established by changing the length and shape of the tube connection
inlet within the reservoir, and/or by changing the position of the
pump inlet, and/or for instance by having the pumping device placed
in the vicinity and in immediate thermal contact with the heat
exchanging surface and/or by providing channels or segments inside
the reservoir.
[0090] In this case, an increased turbulence created by the pumping
device is used to improve the exchange of heat between the heat
exchanging surface and the cooling liquid. Another or an additional
way of improving the heat exchange is to force the cooling liquid
to pass through specially adapted channels or segments being
provided inside the reservoir or by making the surface of the heat
exchanging surface plate inside the reservoir uneven or by adopting
a certain shape of a heat sink with segments. In the figure shown,
the inner surface of the heat exchanging surface facing the
reservoir is plane.
[0091] FIG. 8 is a perspective view of the cooling system showing
the reservoir housing 14 with the heat exchanging surface (not
shown) and the pump (not shown) inside the reservoir. The tube
inlet connection and the tube outlet connection are connected to a
heat radiator by means of connecting tubes 24 and 25 through which
the cooling liquid flows into and out of the reservoir and the heat
radiator, respectively. Within the heat radiator 11, the cooling
liquid passes a number of channels for radiating the heat, which
has been dissipated into the cooling liquid inside the reservoir,
and to the surroundings of the heat exchanger. The air fan 10 blows
air past the channels of the heat radiator in order to cool the
radiator and thereby cooling the cooling liquid flowing inside the
channels through the heat radiator and back into the reservoir.
[0092] According to the invention, the heat radiator 11 may be
provided alternatively. The alternative heat radiator is
constituted by a heat sink, such as a standard heat sink made of
extruded aluminium with fins on a first side and a substantially
plane second side. An air-fan may be provided in connection with
the fins along the first side. Along the second side of the heat
sink a reservoir is provided with at least one aperture intended
for being closed by placing said aperture covering part of,
alternatively covering the whole of, the substantial plane side of
the heat sink. When closing the reservoir in such a way a surface
of the heat sink is in direct heat exchanging contact with an
interior of the reservoir, and thus in direct heat exchanging
contact with the cooling liquid in the reservoir, through the at
least one aperture. This alternative way of providing the heat
radiator may be used in the embodiment shown in FIG. 8 or may be
used as a heat radiator for another use and/or for another
embodiment of the invention.
[0093] A pumping means for pumping the cooling liquid trough the
reservoir may or may not be provided inside the reservoir at the
heat sink. The reservoir may be provided with channels or segments
for establishing a certain flow-path for the cooling liquid through
the reservoir. Channels or segments are especially needed when the
inner surface of the heat exchanging surface is plane and/or when
the inner walls of the reservoir are smooth and/or if the pump is
not situated inside the reservoir. In either of the circumstances
mentioned, the flow of the cooling liquid inside the reservoir may
result in the cooling liquid passing the reservoir too quickly and
not being resident in the reservoir for a sufficient amount of time
to take up a sufficient amount of heat from the heat exchanging
surface. If channels or segments in the reservoir are to be
provided inside the reservoir, the shape and of the channels and
segments may be decisive of whether the reservoir is to be made of
plastic, perhaps by injection moulding, or is to be made of metal
such as aluminium, perhaps by die casting.
[0094] By means of the alternative heat radiator, the heat radiator
11 is not provided as is shown in the figure with the rather
expensive structure of channels leading the cooling liquid along
ribs connecting the channels for improved surface of the structure.
Instead, the heat radiator is provided as described as a unit
constituted by a heat sink with or without a fan and a reservoir,
and thereby providing a simpler and thereby cheaper heat radiator
than the heat radiator 11 shown in the figure.
[0095] The alternative heat radiator provided as an unit
constituted by a heat sink and a reservoir, may be used solely,
with or without a pump inside the reservoir and with or without the
segments or channels, for being placed in direct or indirect
thermal contact with a heat generating processing unit such as CPU
or with the heat exchanging surface, respectively. These
embodiments of the invention may e.g. be used for a reservoir,
where the cooling liquid along a first side within the reservoir is
in direct heat exchanging contact with the heat generating
processing unit such as a CPU and the cooling liquid along a second
side within the reservoir is in direct heat exchanging contact with
a heat sink. Such a reservoir may be formed such as to provide a
larger area of heat exchanging surface towards the heat generating
processing unit such as a CPU than the area of the heat exchanging
surface facing the heat sink. This may e.g. have the purpose of
enlarging the area of the heat exchanging surface so as to achieve
an improved heat dissipation form e.g. the CPU to the heat sink
than that of a conventional heat sink without a reservoir attached.
Conventional heat sinks normally only exchanges heat with the CPU
through the area as given by the area of the top side of the CPU. A
system comprising a liquid reservoir and a heat sink with a fan
provided has been found to be a simple, cost optimised system with
an improved heat dissipation than that of a standard heat sink with
a fan, but without the reservoir. In another embodiment of the
invention, which may be derived from FIG. 8, the air fan and the
heat radiator is placed directly in alignment of the reservoir.
Thereby, the reservoir housing 14, the air fan 10 and the radiator
11 constitute an integrate unit. Such an embodiment may provide the
possibility of omitting the connection tubes, and passing the
cooling liquid directly from the heat radiator to the reservoir via
an inlet connection of the reservoir, and directly from the
reservoir to the heat radiator via an outlet connection of the
reservoir. Such an embodiment may even render the possibility of
both the pumping device of the liquid pump inside the reservoir and
the electrical motor for the propeller of the air fan 23 of the
heat radiator 11 being driven by the same electrical motor, thus
making this electrical motor the only motor of the cooling
system.
[0096] When placing the heat radiator on top of the air fan now
placed directly in alignment with the reservoir and connecting the
heat radiator directly to the inlet connection and outlet
connection of the reservoir, a need for tubes will not be present.
However, if the heat radiator and the reservoir is not in direct
alignment with each other, but tubes may still be needed, but
rather than tubes, pipes made of metal such as copper or aluminium
may be employed, such pipes being impervious to any possible
evaporation of cooling liquid. Also, the connections between such
pipes and the heat radiator and the reservoir, respectively, may be
soldered so that even the connections are made impervious to
evaporation of cooling liquid.
[0097] In the derived embodiment just described, an integrated unit
of the reservoir, the heat exchanging surface and the pumping
device will be given a structure establishing improved heat
radiating characteristics because the flow of air of the air fan
may also be directed along outer surfaces of the reservoir. If the
reservoir is made of a metal, the metal will be cooled by the air
passing the reservoir after having passed or before passing the
heat radiator. If the reservoir is made of metal, and if the
reservoir is provided with segments on the outside surface of the
reservoir, such cooling of the reservoir by the air will be further
improved. Thereby, the integrated unit just described will be
applied improved heat radiating characteristics, the heat radiation
function normally carried out by the heat radiator thus being
supplemented by one or more of the further elements of the cooling
system, i.e. the reservoir, the heat exchanging surface, the liquid
pump and the air fan.
[0098] FIG. 9-10 show an embodiment of a reservoir housing 14,
where channels 25 are provided inside the reservoir for
establishing a forced flow of the cooling liquid inside the
reservoir. The channels 25 in the reservoir housing 14 lead from an
inlet 15 to an outlet 16 like a maze between the inlet and the
outlet. The reservoir housing 14 is provided with an aperture 27
having outer dimensions corresponding to the dimensions of a free
surface of the processing unit 1 to be cooled. In the embodiment
shown, the processing unit to be cooled is a CPU 1.
[0099] When channels 26 are provided inside the reservoir, the
shape of the channels may be decisive of whether the reservoir is
to be made of plastic, perhaps manufactured by injection moulding,
or is to be made of metal such as aluminium, perhaps manufactured
by extrusion or by die casting.
[0100] The reservoir housing 14 or any other parts of the cooling
system, which are possibly manufactured from a plastic material may
be "metallised" in order to minimise liquid diffusion or
evaporation of the liquid. The metal may be provided as a thin
layer of metal coating provided on either or on both of the
internal side or the external side of the plastic part.
[0101] The CPU 1 is intended for being positioned in the aperture
27, as shown in FIG. 10, so that outer boundaries of the CPU are
engaging boundaries of the aperture. Possibly, a sealant (not
shown) may be provided along the boundaries of the CPU and the
aperture for ensuring a fluid tight engagement between the
boundaries of the CPU and the boundaries of the aperture. When the
CPU 1 is positioned in the aperture 27, the free surface (not
shown) of the CPU is facing the reservoir, i.e. the part of the
reservoir having the channels provided. Thus, when positioned in
the aperture 27 (see FIG. 10), the free surface of the CPU 1 is
having direct contact with cooling liquid flowing through the
channels 26 in the reservoir.
[0102] When cooling liquid is forced from the inlet 15 along the
channels 26 to the outlet 16, the whole of the free surface of the
CPU 1 will be passed over by the cooling liquid, thus ensuring a
proper and maximised cooling of the CPU. The configuration of the
channels may be designed and selected according to any one or more
provisions, i.e. high heat dissipation, certain flow
characteristics, ease of manufacturing etc. Accordingly, the
channels may have another design depending on any desire or
requirement and depending on the type of CPU and the size and shape
of the free surface of the CPU. Also. other processing units than a
CPU may exhibit different needs for heat dissipation, and may
exhibit other sizes and shapes of the free surface, leading to a
need for other configurations of the channels. If the processing
unit is very elongate, such as a row of microprocessors, one or a
plurality of parallel channels may be provided, perhaps just having
a common inlet and a common outlet.
[0103] FIG. 11-13 show an embodiment of a heat sink 4, where
segments 28 are provided at a first side 4A of the heat sink, and
fins 29 for dissipating heat to the surroundings are provided at
the other, second side 4B of the heat sink. An intermediate
reservoir housing 30 is provided having a recessed reservoir at the
one side facing the first side 4A of the heat sink. The recessed
reservoir 30 has an inlet 31 and an outlet 32 at the other side
opposite the side facing the heat sink 4.
[0104] When segments 28 are provided on the first side 4A of the
heat sink, the shape of the segments may be decisive of whether the
reservoir, which is made from metal such as aluminium or copper, is
to be made by extrusion or is to be made by other manufacturing
processes such as die casting. Especially when the segments 28 are
linear and are parallel with the fins 29, as shown in the
embodiment, extrusion is a possible and cost-effective means of
manufacturing the heat sink 4.
[0105] The intermediate reservoir 30 or any other parts of the
cooling system, which are possibly manufactured from a plastic
material may be "metallised" in order to minimise liquid diffusion
or evaporation of the liquid. The metal may be provided as a thin
layer of metal coating provided on either or on both of the
internal side or the external side of the plastic part.
[0106] The recessed reservoir is provided with a kind of serration
33 along opposite sides of the reservoir, and the inlet 31 and the
outlet 32, respectively, are provided at opposite corners of the
intermediate reservoir 30. The segments 28 provided at the first
side 4A of the heat sink, i.e. the side facing the intermediate
reservoir 30, are placed so that when the heat sink is assembled
with the intermediate reservoir housing (see FIG. 13) the segments
29 run from one serrated side of the reservoir to the other
serrated side of the reservoir.
[0107] When cooling liquid is forced from the inlet 31 through the
reservoir, along channels (not shown) formed by the segments 29 of
the heat sink 4 and to the outlet 32, the whole of the first side
4A of the heat sink will be passed over by the cooling liquid, thus
ensuring a proper and maximised heat dissipation between the
cooling liquid and the heat sink. The configuration of the segments
on the first side 4A of the heat sink and the configuration of the
serrated sides of the intermediate reservoir housing may be
designed and selected according to any provisions. Accordingly, the
segments may have another design, perhaps being wave-shaped or also
a serrated shape, depending on any desired flow characteristics of
the cooling liquid and depending on the type of heat sink and the
size and shape of the reservoir.
[0108] Also other types of heat sinks, perhaps circular shaped heat
sinks may exhibit different needs for heat dissipation, may exhibit
other sizes and shapes of the free surface, leading to a need for
other configurations of the segments and the intermediate
reservoir. If the heat sink and the reservoir are circular or oval,
a spiral-shaped segmentation or radially extending segments may be
provided, perhaps having the inlet or the outlet in the centre of
the reservoir. If an impeller of the pump is provided, as shown in
FIG. 15-16, the impeller of the pump may be positioned in the
centre of a spiral-shaped segmentation or in the centre of radially
extending segments.
[0109] FIG. 14 shows the reservoir housing 14 shown in FIG. 9-10
and the heat sink 4 and the intermediate reservoir 30 shown in FIG.
11-13 being assembled for thereby constituting an integrated
monolithic unit. It is not absolutely necessary to assemble the
reservoir housing 14 of FIG. 9-10 and the heat sink 4 and the
intermediate reservoir 30 of FIG. 11-13 in order to obtain a
properly functioning cooling system. The inlet 15 and the outlet 16
of the reservoir housing 14 of FIG. 9-10 may be connected to the
outlet 32 and the inlet 31, respectively, of the intermediate
reservoir of FIG. 11-13 by means of tubes or pipes.
[0110] The reservoir housing 14 of FIG. 9-10 and the heat sink 4
and the intermediate reservoir 30 of FIG. 11-13 may then be
positioned in the computer system at different locations. However,
by assembling the reservoir housing 14 of FIG. 9-10 and the heat
sink 4 and the intermediate reservoir 30 of FIG. 11-13 a very
compact monolithic unit is obtained, also obviating the need for
tubes or pipes. Tubes or pipes may involve an increased risk of
leakage of cooling liquid or may require soldering or other special
working in order to eliminate the risk of leakage of cooling
liquid. By eliminating the need for tubes or pipes, any leakage and
any additional working is obviated when assembling the cooling
system.
[0111] FIG. 15-16 show a possible embodiment of a reservoir
according to the invention. The reservoir is basically similar to
the reservoir shown in FIG. 9-10. However, an impeller 33 of the
pump of the cooling system is provided in direct communication with
the channels 26. Also, in the embodiment shown, a heat exchanging
interface 4 such as a surface made from a copper plate,
alternatively a plate of another material having a high thermal
conductivity, is placed between the channels 26 inside the
reservoir and the CPU 1 as the processing unit.
[0112] The heat exchanging surface 4 is preferably made from a
copper plate having a plane outer surface as shown in the figure,
said outer surface being intended for abutting the free surface of
the heat generating component such as the CPU 1 (see FIG. 4).
However, also the inner surface (not shown, see FIG. 7) facing the
reservoir is plane. Accordingly, the copper plate need no machining
other than the shaping of the outer boundaries into the specially
adapted shape used in the embodiment shown and drilling of holes
for insertion of the bolts. No milling of the inner and/or the
outer surface need be provided.
[0113] The provision of the heat exchanging surface 4 need not be a
preferred embodiment, seeing that the solution incorporating the
aperture (see FIG. 9-10) result in a direct heat exchange between
the free surface of the CPU or other processing unit and the
cooling liquid flowing along the channels in the reservoir.
However, the heat exchanging surface enables usage of the cooling
system independently on the type and size of the free surface of
CPU or other processing unit. Also, the heat exchanging surface
enables replacement, repair or other intervention of the cooling
system without the risk of cooling liquid entering the computer
system as such and possibly without the need for draining the
cooling system fully or partly of cooling liquid.
[0114] In the embodiment shown, the heat exchanging surface 4 is
secured to the reservoir by means of bolts 22. Other convenient
fastening means may be used. The heat exchanging surface 4 and thus
the reservoir housing 14 may be fastened to the CPU 1 or other
processing unit by any suitable means such as soldering, brazing or
by means of thermal paste combined with glue. Alternatively,
special means (not shown) may be provided for ensuring a thermal
contact between the free surface of the CPU or other processing
unit and the heat exchanging surface. One such means may be the
fastening means shown in FIG. 4 and FIG. 5 or similar fastening
means already provided as part of the computer system.
[0115] When channels 26 are provided inside the reservoir housing
14, the shape of the channels may be decisive of whether the
reservoir is to be made of plastic, perhaps by injection moulding,
or is to be made of metal such as aluminium, perhaps by die
casting.
[0116] The reservoir housing 14 or any other parts of the cooling
system, which are possibly manufactured from a plastic material may
be "metallised" in order to minimise liquid diffusion or
evaporation of the liquid. The metal may be provided as a thin
layer of metal coating provided on either or on both of the
internal side or the external side of the plastic part.
[0117] The impeller 33 (see FIG. 14) of the pump is positioned in a
separate recess of the channels 26, said separate recess having a
size corresponding to the diameter of the impeller of the pump. The
recess is provided with an inlet 34 and an outlet 35 being
positioned opposite an inlet 31 and an outlet 32 of cooling liquid
to and from, respectively, the channels 26. The impeller 33 of the
pump has a shape and a design intended only for one way rotation,
in the embodiment shown a clock-wise rotation only. Thereby, the
efficiency of the impeller of the pump is highly increased compared
to impellers capable of and intended for both clock-wise and
counter clock-wise rotation.
[0118] The increased efficiency of the impeller design results in
the electric motor (not shown) driving the impeller of the pump
possibly being smaller than otherwise needed for establishing a
proper and sufficient flow of cooling liquid through the channels.
In a preferred embodiment, the electric motor is an AC motor,
preferably a 12V AC motor, although the impeller is intended for a
DC motor. The contradictory use of an AC motor driving a DC
impeller leads to the possibility of an even smaller motor needed
for establishing the proper and sufficient flow of cooling liquid
through the channels.
[0119] The impeller may be driven by an electrical motor at any
voltage common in public electrical networks such as 110V or 220V.
The power supply of the computer system converts the high voltage
AC power to low voltage DC power. Thus, the impeller of the pump
may be driven by an AC or a DC electrical motor. As mentioned,
preferably the impeller of the pump is driven by an AC electrical
motor. Although being technically unnecessary to use an AC
electrical motor and being electrically disadvantageous to use an
AC electrical motor in a computer system supplying DC electrical
power, this may be accomplished by converting part of the DC
electrical power of the power supply of the computer system to AC
electrical power for the AC motor of the pump. However, in the
embodiment shown, the impeller of the pump is driven by a 12V
electrical motor.
[0120] FIG. 17 shows a preferred possible embodiment of a reservoir
according to the invention. The reservoir housing 14, as shown in
FIGS. 17 and 20, is in the form of a double-sided chassis
configured to mount an electrical motor. The reservoir housing 14
has basically the same features as the reservoir housing shown in
FIG. 15-16. In the embodiment shown, the reservoir substantially
has a conical, circular configuration and is provided with
stiffening ribs 36 extending axially along the exterior of the
reservoir housing 14.
[0121] Other shapes such as cylindrical, circular, or conical
rectangular or cylindrical, rectangular or even oval or triangular
shapes may be adopted, when designing and possibly injection
moulding or casting the reservoir. The dimension of the embodiment
shown is approximately 55 mm in diameter and also 55 mm in axial
extension.
[0122] The reservoir housing 14 has a recess 40 in the centre on
the upper side of the reservoir. The recess 40 is intended for
accommodating a stator 37 of an electrical motor driving an
impeller 33 of the pump, said impeller being attached to a shaft 38
of a rotor 39 of the electrical motor. The recess 40 has an orifice
41, four sidewalls 42, a bottom 43 and a circular jacket 44
extending from the bottom 43 of the recess 40 and outwards towards
the orifice 41 of the recess 40. The interior (see FIG. 20) of the
jacket 44 is intended for encompassing the rotor 39 of the pump. As
shown in FIG. 20, the impeller 33 is housed in a recess on the
underside of the reservoir housing 14, the recess being an
extension of the interior of the jacket 44.
[0123] Thereby, a liquid-proof division is made between the rotor
39 of the motor, said rotor 39 being placed inside the interior of
the jacket 44 and being submerged in the cooling liquid, and the
stator 37 of the pump, said stator 37 being positioned in the
recess 40 and surrounding the exterior of the jacket 44.
Accordingly, the stator 37 need not be sealed against the cooling
liquid, because the recess 40 together with the jacket 44 ensures
the stator staying dry from the cooling liquid, but the stator 37
still being capable of driving the rotor 39, when being supplied
with electrical power from a power supply (not shown) of the
computer system.
[0124] Along an outer circumferential extension, the reservoir
housing 14 is provided with protrusions 45 extending outwardly from
the circumferential extension. The protrusions are intended for
cooperating with a clip (see description below) for fastening the
reservoir housing 14 to the CPU or other processing unit of the
computer system. The protrusions 45 are shown as a plurality of
singular protrusions. Alternatively, the protrusions may be only
one continuous protrusion extending outwardly and around the
circumferential extension.
[0125] The reservoir housing 14 may also be provided with an inlet
(not shown) and an outlet (not shown) for the cooling liquid. The
inlet and the outlet are provided along a surface of the reservoir
facing downward and inwards when seen in the perspective view of
the drawing. The inlet and the outlet lead to a radiator (not
shown) intended for cooling the cooling liquid after having been
heated by the processing unit via a heat exchanging surface (see
description below).
[0126] The radiator may be placed nearby or distant from the
reservoir housing 14, depending on the set-up of the computer
system. In one possible embodiment, the radiator is placed in the
immediate vicinity of the reservoir, thereby possible excluding any
tubing extending between the radiator and the inlet and the outlet,
respectively. Such embodiment provides a very compact configuration
of the entire cooling system, namely a monolithic configuration
where all elements needed for the cooling system are incorporated
in one unit.
[0127] In an alternative embodiment, the reservoir housing 14
itself also constitutes the radiator of the cooling system. In such
embodiment, an inlet and an outlet are not needed. If the reservoir
is made of a metal such as copper or aluminium or other material
having a high thermal conductance, the cooling liquid, after having
been heated by the processing unit via a heat exchanging surface 8
see description below) may radiate the heat via the exterior
surface of the reservoir housing 14 itself. In such embodiment, the
ribs 36 along the exterior surface of the reservoir housing 14 may
also, or may in stead, function as cooling fins. In such
embodiment, the fins will have a smaller dimension than the
transverse dimension of the ribs 14 shown in FIG. 17, and the
number of fins will be greater than the number of fins shown in
FIG. 17.
[0128] An impeller 33 of the pump of the cooling system is provided
in direct communication with a pump chamber 46 formed by impeller
cover 46A having an outlet 34 provided tangentially to the
circumference of the impeller 33. Thus, the pump functions as a
centrifugal pump. The inlet of the pump chamber 46 is the entire
opening into the cavity that the pump chamber configures, said
cavity being in direct communication with the interior of the
reservoir housing 14 as such. An intermediate member 47 is provided
between the pump chamber 46 together with the interior of the
reservoir and a heat exchanging interface 4. The intermediate
member 47 is provided with a first passage 48 for leading cooling
liquid from the pump chamber 46 to a thermal exchange chamber 47A
provided at the opposite of the intermediate member 47. The
intermediate member 47 is provided also with a second passage 49
for leading cooling liquid from the thermal exchange chamber 47A
provided at the opposite of the intermediate member 47 to the
interior of the reservoir housing 14. Thus, the area enclosed
between the underside of the reservoir housing 14 and the heat
exchange surface 4 constitutes an enclosed space for circulating
the cooling liquid therethrough. The enclosed spaced is divided
into two separate chambers by the impeller cover 46A and the
intermediate member 47, as shown in FIG. 20. The impeller cover 46A
interfaces with the recess on the underside of the reservoir 14 to
define the pump chamber 46 which houses the impeller 33, while the
intermediate member 47 and the heat exchange surface 4 together
define the thermal exchange chamber 47A.
[0129] In the embodiment shown, a heat exchanging interface 4 such
as a surface made from a copper plate, alternatively a plate of
another material having a high thermal conductivity, is placed in
thermal communication with the thermal exchange chamber (not shown)
at the opposite side of the intermediate member 47.
[0130] The heat exchanging interface 4 is preferably made from a
copper plate having a plane outer surface (not shown) at the
opposite side as the side shown in the figure, said outer surface
being intended for abutting the free surface of the heat generating
component such as the CPU (see FIG. 4). The inner surface facing
the thermal exchange chamber (not shown) at the opposite side of
the intermediate member 47 is provided with pins 4B extending from
the base of the copper plate and into the thermal exchange chamber
(not shown) at the opposite side of intermediate member 47. The
pins 4B constitutes an uneven surface and may either be provided
during casting of the copper plate or may be provided by means of
milling or other machining process of a copper plate. The pins
provide a network of channels across the inner surface of the heat
exchanging interface, along which network the cooling liquid is
intended to flow.
[0131] Alternatively, also the inner surface of the copper plate
facing the reservoir is plane. In this alternative embodiment, the
copper plate need no machining other than the shaping of the outer
boundaries into the specially adapted shape used in the embodiment
shown. No milling or other machining process of the inner and/or
the outer surface need be provided, when both the outer surface and
the inner surface is plane.
[0132] The provision of the heat exchanging interface 4 need not be
a preferred embodiment, seeing that the solution incorporating the
aperture (see FIG. 9-10) result in a direct heat exchange between
the free surface of the CPU or other processing unit and the
cooling liquid flowing along the channels in the reservoir.
However, the heat exchanging interface enables usage of the cooling
system independently on the type and size of the free surface of
CPU or other processing unit. Also, the heat exchanging interface
enables replacement, repair or other intervention of the cooling
system without the risk of cooling liquid entering the computer
system as such and possibly without the need for draining the
cooling system fully or partly of cooling liquid.
[0133] In the embodiment shown, the heat exchanging interface 4 is
secured to the intermediate member 47 by means of gluing or other
means ensuring a proper and liquid-tight fastening of the heat
exchanging interface with the intermediate member. Any other
suitable and convenient means (not shown) for securing the heat
exchanging interface to the intermediate member may be
envisaged.
[0134] The heat exchanging interface and thus the reservoir is
fastened to the top of the CPU by means of a clip 50. The clip 50
has a circular configuration and has four legs 51 extending axially
from the circular configuration. The four legs 51 are provided with
footing 52 and the footings 52 are provided with holes 53. The clip
50 is intended for being displaced around the exterior of the
reservoir housing 14 and further axially to the protrusions 45 of
the reservoir housing 14.
[0135] The clip 50, after having been placed around the reservoir
housing 14, is fastened to the motherboard of the computer system
by means of bolts (not shown) or the like fastening means extending
through the holes 53 in the footings 52 and further though
corresponding holes in the motherboard. The corresponding holes in
the motherboard are preferably holes already available in the
motherboard in the vicinity of the CPU and the socket of the CPU,
respectively. Accordingly, the legs 51 and the footings 52 of the
clip 50 are specially designed in accordance with the already
provided holes in the motherboard.
[0136] Alternatively, the heat exchanging interface 4 and thus the
reservoir housing 14 may be fastened to the CPU or other processing
unit by any other suitable means such as soldering, brazing or by
means of thermal paste combined with glue. Alternatively, special
means (not shown) may be provided for ensuring a thermal contact
between the free surface of the CPU or other processing unit and
the heat exchanging interface. One such means may be the fastening
means shown in FIG. 4 and FIG. 5 or similar fastening means already
provided as part of the computer system.
[0137] When stiffening and/or cooling fins 36 are provided at the
exterior of the reservoir housing 14, the shape of and the number
of fins may be decisive of whether the reservoir is to be made of
plastic, perhaps by injection moulding, or is to be made of metal
such as aluminium, perhaps by die casting. Also, the purpose of the
fins i.e. just for stiffening the reservoir, or also or in stead
for cooling purposes, may be decisive of whether the reservoir is
to be made of plastic, perhaps by injection moulding, or is to be
made of metal such as aluminium, perhaps by die casting.
[0138] The reservoir housing 14 or any other parts of the cooling
system, which are possibly manufactured from a plastic material may
be "metallised" in order to minimise liquid diffusion or
evaporation of the liquid. The metal may be provided as a thin
layer of metal coating provided on either or on both of the
internal side or the external side of the plastic part.
[0139] The impeller 33 of the pump has a shape and a design
intended only for one way rotation, in the embodiment shown a
clock-wise rotation only. Thereby, the efficiency of the impeller
of the pump is highly increased compared to impellers capable of
and intended for both clock-wise and counter clock-wise
rotation.
[0140] The increased efficiency of the impeller design results in
the electric motor (not shown) driving the impeller of the pump
possibly being smaller than otherwise needed for establishing a
proper and sufficient flow of cooling liquid through the channels.
In a preferred embodiment, the electric motor is an AC motor,
preferably a 12V AC motor, although the impeller is intended for a
DC motor. The contradictory use of an AC motor driving a DC
impeller leads to the possibility of an even smaller motor needed
for establishing the proper and sufficient flow of cooling liquid
through the channels.
[0141] The impeller may be driven by an electrical motor at any
voltage common in public electrical networks such as 110V AC power
or 220V AC power. The power supply of the computer system converts
the high voltage AC power to low voltage DC power. Thus, the
impeller of the pump may be driven by either an AC or a DC
electrical motor. As mentioned, preferably the impeller of the pump
is driven by an AC electrical motor. Although being technically
unnecessary to use an AC electrical motor and being electrically
disadvantageous to use an AC electrical motor in a computer system
supplying DC electrical power, this may be nevertheless be
accomplished by converting part of the DC electrical power of the
power supply of the computer system to AC electrical power for the
AC motor of the pump.
[0142] In every aspect of the invention, where an AC motor is used
for driving an impeller from a DC motor, although this way of
configuring a pump is contradictory, the following preferred mode
of operation is established for alleviating the disadvantages:
[0143] In order to be able to control direction of rotation of the
impeller attached to the rotor and to optimise the conditions of
maximum average torque value during starting, i.e. from zero speed
up to the synchronous speed, an electronic control circuit is used.
The electronic control circuit comprises a processing unit, which
drives a static power switch, constituted for example by a triac
arranged in series between the alternating-voltage power, which is
obtained form the DC power supply of the computer system, and the
AC motor. The same series network also includes a detector for the
current I which flows through the triac and then through the AC
motor. The output of the current detector is an input signal for
the electronic processing unit.
[0144] The electronic control circuit may also comprise a number or
sensors suitable for detecting the position and polarity of the
permanent magnets comprised in the rotor of the AC motor, both when
the rotor is moving and when it is in particular operating
conditions, or when it is motionless or stalled at zero speed. The
number of position sensors may be Hall sensors, encoders or optical
or electromechanical sensors capable of establishing and/or
measuring the position of the rotor. The output signal from the
number of position sensors is an input signal for the electronic
processing unit.
[0145] Alternatively, the output signal from the position sensor
may be phase shifted by means of an electronic phase shifting
circuit before the output signal is sent to the input of the
electronic processing unit.
[0146] A third signal may be input to the processing unit, said
third signal enabling the processing unit to detect the polarity of
the AC voltage applied to the AC motor. However, the third signal
is not compulsory.
[0147] The signals input to the electronic processing unit are
converted into digital form and after being processed by the
processing unit, an output signal is provided by the processing
unit. The output signal is used for closing or opening the static
switch constituted by a triac arranged in series with the AC
motor.
[0148] In the electronic processing unit, the current signal
provided by the current sensor enters a zero-crossing detector
which provides in output a logical "1" signal indicating that said
current approaches zero with a positive or negative deviation from
the zero value of said current. This deviation depends on the type
of motor used and on its application, as well as on the type of
static power switch being used. The signal arriving from the
position sensor enters a phase-shift and processing circuit the
output whereof is 1 or 0 according to the position and polarity of
the rotor.
[0149] In the electronic processing unit, the phase shifted
position signal as well as the signal processed from the AC
voltage, enter an electronic logic XOR gate which outputs a "1"
signal if the digital value of the AC voltage is equal to "0" and
the digital value of the phase shifted position signal is equal to
"1" or the digital value of the AC voltage is equal to "1" and the
digital value of the phase shifted position signal is equal to
"0".
[0150] The output of the zero-crossing detector and the output of
the XOR gate, thus in digital form, enter an electronic logic AND
gate which provides in output the control signal for closing or
opening the static power switch.
[0151] The AND gate with two inputs and the signal processing
system allow determining two conditions: 1) the AC voltage signal
is positive, the current is proximate to zero, and the rotor
rotation angle is between 0 degrees and 180 degrees; 2) the AC
voltage signal is negative, the current is proximate to zero, and
the rotor rotation angle is between 180 degrees and 360 degrees.
These two conditions provide the same rotation direction of the
rotor of the AC motor.
[0152] FIG. 18 shows an embodiment of an AC motor in which one
stator pole 54 is longer than the other stator pole 55 by an amount
indicated by I. With this configuration the permanent-magnet rotor
39 with an ideal line 56 separating the north N and the south S of
the rotor, is positioned so that the ideal line 56 do not coincide
with the median axis 57 of the stator 37, but so that the ideal
line 56 is tilted by a certain angle .alpha. in respect to the
median 57 of the stator 37.
[0153] Two energising windings 58, 59 are provided on the two poles
54,55 of the stator 37, respectively, and the energising windings
are connected in series and are powered, through terminals (not
shown), by an AC power source. With this configuration of the AC
motor, the motor is able to start more easily in an intended
rotational direction of the rotor.
[0154] In a preferred embodiment of the invention, the control
electronics supplies the AC motor with only a half-wave voltage
signal during start up, thereby providing torque pulses to the
rotor. Since only a half-wave voltage signal is supplied to the
motor, the torque pulses are always unidirectional and will
therefore force the rotor to start rotating in a required
direction. The required direction of rotation is determined by the
design of the impeller attached to the rotor and by polarity of the
half-wave voltage signal.
[0155] After some amount of time, in which a number of half-wave
voltage signals has been supplied to the motor, the rotor will stop
rotating at a certain position e.g. as shown in the figure. Thus,
the rotor is brought into a determined steady state position that
is independent of its start position. Subsequent to this process,
the AC motor is supplied with a full-wave voltage signal that will
accelerate the rotor until the motor enters synchronous operation,
that is, when the rotor rotates with the same cyclic frequency as
the frequency of the AC voltage source.
[0156] The initial polarity of the AC voltage signal is
determinative for the resulting direction of rotation of the rotor,
thus if the initial voltage is positive with an increasing
amplitude, the rotor will start rotating in one direction, whereas
if the voltage is negative with a decreasing amplitude, the rotor
will start rotating in an opposite direction.
[0157] The number of half-waves required for bringing the rotor
into a determined steady state position, where the rotor stops
rotating, depends on the characteristics of the motor such as
moment of inertia and the external load applied to the rotor. Thus,
the number of half-waves required is based on empirical analysis of
a particular motor in particular load conditions.
[0158] The half-wave voltage signal and the corresponding half-wave
current signal supplied to the motor will have an appearance as
shown in FIG. 19.
[0159] In an alternative embodiment the control electrics used to
drive the AC motor shown if FIG. 18 is configured so that that the
control electronics dictates the AC motor to stop at a
predetermined position by supplying the motor with a number of
half-wave voltage signals subsequent to the synchronous operation
in which the motor was supplied with a full-wave voltage signal.
Thus, at the time the motor needs to be started again, the rotor is
already in a position so that only the polarity of the full-wave AC
voltage signal supplied to the motor must be chosen so that the
resulting direction of rotation of the rotor is in conformity with
the terminal position of the rotor at the last operation.
[0160] According to this method, the initial step of bringing the
rotor into a determined steady state position by supplying the
motor with a number of half-wave voltage signals is not required.
Even in the alternative, it will be possible to both terminate the
full-wave power supply with a number of half-wave voltage signals
as well as commencing the full-wave power supply by initially
supplying the motor with a number of half-wave signals. However,
this is more cumbersome, but nevertheless more safe.
[0161] FIG. 19 shows a voltage signal V and a current signal I
applied to the AC motor as well as the position signal of the
rotor. Initially the rotor stands still, which is represented by
the straight line L. The electronic control circuit controls the
static power switch so that the voltage signal V and the current
signal I are present as half-waves. Thus, the rotor receives torque
pulses due to the current-voltage combination; these pulses are
always one-way directional and tend to start the rotor moving in
the required direction. Subsequent to the start-up phase, the rotor
enters into its synchronous operation.
[0162] Thus, an AC signal is generated, preferably a 12 V AC
signal, possibly by means of digital electric pulses from the 12 V
DC power supply of the computer's power supply. Based on a possible
sensor output relating to the impeller position, a decision is made
of how to initiate the AC power signal, i.e. with a negative or
positive half-wave, and by doing making sure the impeller starts in
the same rotational direction each time and thus the performance
benefits of the AC pump is similar to those of a DC pump.
[0163] Alternatively, the magnetic field sensor is omitted, and
instead of reading the impeller position, the impeller is forced to
be in the same position every time the impeller starts. To be sure
the impeller is in a defined position before start, a signal is
supplied to the stator of the AC motor for a defined period of
time. The signal is supplied perhaps three times in a row according
to the curvature of the electrical power source. The pulses must be
within the same half-wave part of a signal period. The frequency of
the pulsed signal is arbitrary, but may be 50/60 Hz, although,
despite the fact that under normal circumstances an AC pump being
driven by the AC signal from the power outlet of the public
electrical power network and transformed from 230/115 V to 12V
would not function, as there is no chance of changing the sine
signal from the public network.
[0164] By this way the impeller will be forced to the right
polarity before start, and the pump will start turning the impeller
in a defined way of rotation when the power signal full-wave is
supplied. The full-wave power signal, which is supplied, must start
in the opposite signal half-wave amplitude than that of the initial
half-wave pulses, that was supplied before start of the full-wave
power signal.
[0165] The invention has been described with reference to specific
embodiments and with reference to specific utilisation, it is to be
noted that the different embodiments of the invention may be
manufactured, marketed, sold and used separately or jointly in any
combination of the plurality of embodiments. In the above detailed
description of the invention, the description of one embodiment,
perhaps with reference to one or more figures, may be incorporated
into the description of another embodiment, perhaps with reference
to another or more other figures, and vice versa. Accordingly, any
separate embodiment described in the text and/or in the drawings,
or any combination of two or more embodiments is envisaged by the
present application.
* * * * *