U.S. patent application number 13/942922 was filed with the patent office on 2013-11-14 for cooling system for a computer system.
This patent application is currently assigned to Asetek A/S. The applicant listed for this patent is Asetek A/S. Invention is credited to Andre Sloth ERIKSEN.
Application Number | 20130299158 13/942922 |
Document ID | / |
Family ID | 34572977 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130299158 |
Kind Code |
A1 |
ERIKSEN; Andre Sloth |
November 14, 2013 |
COOLING SYSTEM FOR A COMPUTER SYSTEM
Abstract
A cooling system for a computer system comprises at least one
unit such as a central processing unit (CPU) generating thermal
energy and 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;
(Morgan Hill, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asetek A/S |
Bronderslev |
|
DK |
|
|
Assignee: |
Asetek A/S
|
Family ID: |
34572977 |
Appl. No.: |
13/942922 |
Filed: |
July 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13547240 |
Jul 12, 2012 |
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13942922 |
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12826768 |
Jun 30, 2010 |
8240362 |
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13547240 |
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10578578 |
May 5, 2006 |
7971632 |
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PCT/DK04/00775 |
Nov 8, 2004 |
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12826768 |
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Current U.S.
Class: |
165/287 ;
165/104.31 |
Current CPC
Class: |
F28D 15/00 20130101;
G06F 1/20 20130101; H05K 7/20154 20130101; H05K 7/20272 20130101;
G06F 1/206 20130101; F28F 2250/08 20130101; G06F 2200/201 20130101;
H05K 7/20263 20130101 |
Class at
Publication: |
165/287 ;
165/104.31 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1. A cooling system for a computer system processing unit,
comprising: a reservoir configured to circulate a cooling liquid
therethrough, the reservoir including: an upper chamber and a lower
chamber, wherein the upper chamber and the lower chamber are
vertically displaced separate fluid-containing receptacles that are
each surrounded by boundary walls, wherein at least one of the
boundary walls separate the upper chamber from the lower chamber,
one or more passageways connecting the upper chamber and the lower
chamber, at least one of the one or more passageways being
positioned on the boundary wall that separates the upper chamber
from the lower chamber; a heat exchanging interface removably
attached to the reservoir to form a boundary wall of the lower
chamber, the heat exchanging interface being adapted to provide
separable thermal contact between the processing unit and the
cooling liquid; a centrifugal pump having a motor arid an impeller,
the impeller being positioned within the reservoir; and a heat
exchanger spaced apart and fluidly coupled to the integrated
element.
2. The cooling system of claim 1, further including a control
system, wherein the control system is configured to adjust a speed
of the pump.
3. The cooling system of claim 2, wherein the control system is
part of an operating system of the computer.
4. The cooling system of claim 2, wherein the control system is
configured to measure one of an operating load or an operating
temperature of the processing unit and adjust the pump based on the
measured value.
5. The cooling system of claim 1, wherein the control system is
configured to sense a position of the impeller, and select a
rotational direction of the impeller.
6. The cooling system of claim 1, wherein the control system is
configured to determine a required cooling capacity of the cooling
system and adjust a rotational speed of the pump based on the
required cooling capacity.
7. The cooling system of claim 6, wherein the control system is
configured to reduce the rotational speed of the pump if lower
cooling capacity is required.
8. The cooling system of claim 2, wherein the control system is
configured to adjust a rotational speed of the fan and a rotational
speed of the pump to reduce noise and provide a required cooling
capacity of the cooling system.
9. The cooling system of claim 1, wherein at least one of the one
or more passageways has a substantially circular shape.
10. A cooling system for a processing unit positioned on a
motherboard of a computer, comprising: a reservoir configured to be
coupled to the processing unit positioned on the motherboard at a
first location, the reservoir being adapted to pass a cooling
liquid therethrough, wherein the reservoir includes an upper
chamber and a lower chamber, the upper chamber and the lower
chamber being separate cooling liquid containing receptacles that
are vertically spaced apart and separated by at least a wall, the
upper chamber and the lower chamber being connected together by one
or more passageways, at least one of the one or more passageways
being positioned on the wall, the reservoir further including a
heat exchanging interface configured to be placed in separable
thermal contact with the processing unit, the heat exchanging
interface being attached to the reservoir such that the heat
exchanging interface forms a boundary wall of the lower chamber of
the reservoir; a heat exchanger fluidly coupled to the reservoir
and configured to be positioned at a second location spaced apart
from the first location when the reservoir is coupled to the
processing unit; a fan adapted to direct air to the heat exchanger
to dissipate heat from the cooling liquid to surrounding
atmosphere; a pump configured to circulate the cooling liquid
between the reservoir and the heat exchanger, the pump including a
motor having a rotor, a stator, and an impeller, the impeller being
positioned in the reservoir; and a control system configured to
adjust a rotation speed of the pump.
11. The cooling system of claim 10, wherein the control system is
configured to adjust the rotation speed based on a temperature of
the processing unit.
12. The cooling system of claim 10, wherein the control system is
configured to select a rotational direction of the impeller.
13. The cooling system of claim 10, wherein the control system is
configured to adjust a speed of the fan independent of a speed of
the pump.
Description
[0001] This is a continuation application of application Ser. No.
13/547,240 filed Jul. 12, 2012, which is a continuation application
of application Ser. No. 12/826,768 filed Jun. 30, 2010 (issued on
Aug. 14, 2012 as U.S. Pat. No. 8,240,362), which is a divisional of
application Ser. No. 10/578,578, filed May 5, 2006 (issued on Jul.
5, 2011 as U.S. Pat. No. 7,971,632 B2), which is a U.S. national
phase application of PCT/DK2004/000775 filed on Nov. 8, 2004. These
applications are incorporated by their entirety herein by
reference.
BACKGROUND OF THE INVENTION
[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 OF INVENTION
[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 he 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 preferred embodiments according to this aspect of the
invention, the 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] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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
front said power supply is intended for being converted to AC being
supplied to the electrical motor.
[0016] It may be advantageous to use an AC motor, such as a 12V AC
motor, for driving the pump in order to obtain a stable 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. 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.
[0017] 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.
[0018] 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.
[0019] 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 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, 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.
[0020] Providing a plane heat exchanging surface, both the first,
inner side and on the second, outer side, results in the costs for
manufacturing the heat exchanging surface is reduced to an absolute
minimum. 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. The solution to this problem according to the
invention 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.
[0021] 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 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 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.
[0022] 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 surface and the
CPU.
[0023] 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.
[0024] 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, 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.
[0025] 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.
[0026] 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 voltage being performed by the computer
system for applying the AC voltage from the electrical power supply
of the computer system during conversions of the electrical DC
voltage of the power supply to AC voltage for the electrical
motor.
[0027] 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
[0028] The invention will hereafter be described with reference to
the drawings, where
[0029] FIG. 1 shows an embodiment of the prior art. The figure
shows the typical components in an air-cooling type CPU cooling
arrangement.
[0030] 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.
[0031] FIG. 3 shows an embodiment of the prior art. The figure
shows the typical components in a liquid-cooling type CPU cooling
arrangement.
[0032] FIG. 4 is an exploded view of the invention and the
surrounding elements.
[0033] FIG. 5 shows the parts shown in the previous figure when
assembled and attached to the motherboard of a computer system.
[0034] 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.
[0035] FIG. 7 is a cutout view into the reservoir housing the pump
and an inlet and an outlet extending out of the reservoir.
[0036] FIG. 8 is a view of the cooling system showing the reservoir
connected to the heat radiator.
[0037] 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.
[0038] FIG. 11-13 are perspective views of a possible embodiment of
heat sink and a reservoir housing constituting an integrated
unit.
[0039] 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.
[0040] FIG. 15-16 are perspective view of a preferred embodiment of
a reservoir and a pump and a heat exchanging surface constituting
an integrated unit.
DETAILED DESCRIPTION OF THE INVENTION
[0041] 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 4 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.
[0042] 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 4 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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 as sealant 5
provided between the housing and the heat exchanging interface.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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 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.
[0054] 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.
[0055] A sealant in form of a gasket 13 is used for the connection
between the reservoir 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 p vide a swirling of the cooling liquid inside the
reservoir.
[0056] However, apart from the non-smooth walls of the reservoir
and the pump being situated inside the reservoir, the reservoir may
he 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 he provided inside the reservoir, the shape and of the
channels and segments may he 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.
[0057] 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. 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.
[0058] 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.
[0059] 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. 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.
[0060] 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 he limited, thereby limiting the noise generating
by the motor driving the pump.
[0061] 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. 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.
[0062] The pump is not being restricted to a mechanical device, but
can he 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.
[0063] 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.
[0064] 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.
[0065] FIG. 8 is a perspective view of the cooling system showing
the reservoir 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.
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.
[0066] 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.
[0067] 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.
[0068] 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 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.
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.
[0069] 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.
[0070] 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 14 lead from an inlet
15 to an outlet 16 like a maze between the inlet and the outlet.
The reservoir 14 is provided with an aperture 27 having outer
dimensions corresponding to the dimensions of a free surface of the
processing unit 1 to he cooled. In the embodiment shown, the
processing unit to be cooled is a CPU 1.
[0071] 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 he made of metal such as aluminium, perhaps manufactured
by extrusion or by die casting.
[0072] The reservoir 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. 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.
[0073] 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.
[0074] 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.
[0075] When segments 28 are provided on the first side 4A of the
heat sink, the shape of the segments may he decisive of whether the
reservoir, which is made from metal such as aluminium or copper, is
to he made by extrusion or is to he 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.
[0076] 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. 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.
[0077] 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.
[0078] 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 he
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.
[0079] FIG. 14 shows the reservoir 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 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 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.
[0080] The reservoir 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 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.
[0081] 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.
[0082] 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.
[0083] 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.
[0084] 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 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.
[0085] When channels 26 are provided inside the reservoir 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.
[0086] The reservoir 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. 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.
[0087] 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, leading to the possibility of an even
smaller motor needed for establishing the proper and sufficient
flow of cooling liquid through the channels.
[0088] The impeller of the pump may be driven by an AC or a DC
electrical motor. However, as mentioned, preferably the impeller of
the pump is driven by an AC electrical motor. Although being
technically and electrically unnecessary to use an AC electrical
motor 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 impeller of the pump. The
impeller 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 impeller of the pump is driven by a 12V
electrical motor.
[0089] 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 he
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.
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