U.S. patent application number 11/160423 was filed with the patent office on 2005-10-06 for computer cooling system.
Invention is credited to Chang, Ting-Yu, Cheng, Yu-Chih, Ho, Wei-Chuan, Yao, Jin-Wang, Zheng, Lin.
Application Number | 20050217300 11/160423 |
Document ID | / |
Family ID | 33539458 |
Filed Date | 2005-10-06 |
United States Patent
Application |
20050217300 |
Kind Code |
A1 |
Cheng, Yu-Chih ; et
al. |
October 6, 2005 |
COMPUTER COOLING SYSTEM
Abstract
A cooling system includes a cooling fan, a fan input-output
module for transmitting a control signal to the fan for controlling
the rotational speed of the fan, and a chipset interface for
generating the fan control signal based on a change in a vital
temperature of the computer system. Further provided is a
controller for receiving the vital temperature and forwarding the
vital temperature to the chipset interface, and a temperature
transducer for generating the vital temperature and outputting the
vital temperature to the controller. The chipset interface monitors
a rotational speed of the cooling fan, and monitors a vital
temperature of the computer system. The chipset interface then sets
the fan power based on a change in the vital temperature. When the
vital temperature decreases, the fan power is reduced to slow the
fan, and when the vital temperature increases, the fan power is
increased to speed the fan.
Inventors: |
Cheng, Yu-Chih; (Taipei
Hsien, TW) ; Zheng, Lin; (Taipei Hsien, TW) ;
Ho, Wei-Chuan; (Taipei Hsien, TW) ; Yao,
Jin-Wang; (Taipei Hsien, TW) ; Chang, Ting-Yu;
(Taipei Hsien, TW) |
Correspondence
Address: |
NORTH AMERICA INTERNATIONAL PATENT OFFICE (NAIPC)
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
33539458 |
Appl. No.: |
11/160423 |
Filed: |
June 23, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11160423 |
Jun 23, 2005 |
|
|
|
10601783 |
Jun 24, 2003 |
|
|
|
Current U.S.
Class: |
62/259.2 ;
361/679.48; 62/186 |
Current CPC
Class: |
Y02D 10/16 20180101;
Y10S 236/09 20130101; Y02D 10/00 20180101; H05K 7/20209 20130101;
G06F 1/206 20130101 |
Class at
Publication: |
062/259.2 ;
361/687; 062/186 |
International
Class: |
F25D 017/04; F25D
023/12; H05K 005/00; F25B 021/02; G06F 001/20; H05K 007/20 |
Claims
What is claimed is:
1. A method for controlling an operating temperature of a computer
system, the method comprising: monitoring a rotational speed of at
least a cooling fan of the computer system, the rotational speed of
the cooling fan being controlled by a fan power; monitoring a vital
temperature of the computer system; calculating a change in the
vital temperature; and setting the fan power based on the
calculated change in the vital temperature; wherein when the change
in the vital temperature is negative, the fan power is reduced to
reduce the fan rotational speed; and when the change in the vital
temperature is positive, the fan power is increased to increase the
fan rotational speed; wherein setting the fan power further
comprises: maintaining the fan power when the vital temperature
increases and the vital temperature is below a set temperature;
maintaining the fan power when the vital temperature remains
constant and the vital temperature is above the set temperature;
and decreasing the fan power by a third power when the vital
temperature remains constant and the vital temperature is below the
set temperature.
2. The method of claim 1 wherein setting the fan power further
comprises: increasing the fan power by a first power when the vital
temperature increases by a first temperature, the first power being
directly proportional to the first temperature.
3. The method of claim 1 wherein setting the fan power further
comprises: decreasing the fan power by a second power when the
vital temperature decreases by a second temperature, the second
power being directly proportional to the second temperature.
4. A method for controlling an operating temperature of a computer
system, the method comprising: monitoring a rotational speed of a
cooling fan installed in a power supply of the computer system, the
rotational speed of the cooling fan being controlled by a fan
power; monitoring a vital temperature of the computer system;
calculating a change in the vital temperature; and setting the fan
power according to the calculated change in the vital temperature
to control the rotational speed of the power supply cooling fan;
wherein setting the fan power further comprises: maintaining the
fan power when the vital temperature increases and the vital
temperature is below a set temperature; maintaining the fan power
when the vital temperature remains constant and the vital
temperature is above the set temperature; and decreasing the fan
power by a third power when the vital temperature remains constant
and the vital temperature is below the set temperature.
5. The method of claim 4 wherein setting the fan power further
comprises: increasing the fan power by a first power when the vital
temperature increases by a first temperature, the first power being
directly proportional to the first temperature.
6. The method of claim 4 wherein setting the fan power further
comprises: decreasing the fan power by a second power when the
vital temperature decreases by a second temperature, the second
power being directly proportional to the second temperature.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of application Ser. No.
10/601,783, filed Jun. 24, 2003.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a cooling system for a
computer, and more specifically, to a fan speed controlling cooling
system for a personal computer.
[0004] 2. Description of the Prior Art
[0005] As computer processing speeds steadily increase, the need
for high capacity cooling systems becomes essential. Proper cooling
prevents heat related failure of the processor when under operating
loads. Typical cooling systems have progressed beyond the venerable
constantly running fan to include temperature sensors and related
control circuits for dynamically adjusting fan speed. While several
fan speed control schemes have been developed, nearly all focus
entirely on maximizing cooling effects or reducing power
consumption. One aspect of fan control has been continuously
neglected in development of control schemes and related circuitry,
that is, fan noise level.
[0006] In the article Hanrahan, D. "Fan-Speed Control Techniques in
PCs" Analog Dialogue Vol. 34, No. 4 (June-July 2000), which is
incorporated herein by reference, several fan speed control schemes
and circuits are described in detail. The first is a two-step fan
control method in which a thermistor installed near a CPU or an
on-die thermal monitoring transistor outputs a system temperature
to a BIOS. The BIOS then switches a cooling fan on or off depending
on the system temperature, a marked improvement over a constantly
running fan. Similar to the two-step method, a three-step fan
control method adds an additional half-speed setting for the fan.
The half-speed setting is enabled when the processor is engaged in
light duty generating little heat. The third method, a linear
fan-speed control method, includes digital logic components that
enable a range fan speeds based on the measured system temperature.
The linear method is quite simply an extension of the three-speed
method. Finally, a similar pulsewidth-modulation fan-speed control
method allows fan speed to be controlled by adjusting fan signal
duty cycle. While these are just a sampling of conventional fan
speed control methods, they are representative of the current
technology.
[0007] To realize linear fan-speed control methods such as that
described above, circuits having the required operational logic
have been developed. FIG. 1 illustrates a general state-of-the-art
computer fan speed control circuit 10. The circuit 10 includes a
fan 12 connected to a chipset controller 14 through a fan
input-output interface 16. Generally, the chipset controller 14
contains logic linearly relating fan speeds to measured
temperatures, and generates and outputs a corresponding control
signal. Based on a temperature measured at a sensor 18, the chipset
controller 14 outputs the control signal to the fan I/O 16, which
controls the rotational speed of the fan 12. In an example of a
specific conventional implementation, subcomponents of the blocks
of the circuit 10 are as disclosed in Steele, J. "An I.sup.2C Fan
for Personal Computers" Electronic Design Aug. 3, 1998, which is
incorporated herein by reference. In an example of a linear
fan-speed control method, the chipset controller 14 is programmed
with a series of trigger temperatures and a corresponding series of
signals having encoded fan speeds, which are directly proportional
to the series of trigger temperatures. Thus, the controller 14
outputs a fan control signal identifying a fan speed corresponding
to the temperature trigger reached.
[0008] The prior art methods of controlling a fan to cool a
processor cannot suitably meet current cooling requirements. Having
been developed for performance and power savings, these methods
typically suffer in other areas of concern. Specifically, noise
levels can be uncomfortably high in conventional fan cooling
applications.
SUMMARY OF THE INVENTION
[0009] It is therefore a primary objective of the claimed invention
to provide a cooling system for a computer that minimizes fan noise
level while improving cooling performance and power
conservation.
[0010] Briefly summarized, the claimed invention method monitors a
rotational speed of at least a cooling fan of the computer system,
the rotational speed of the cooling fan being controlled by a fan
power, and further, monitors a vital temperature of the computer
system. The method then sets the fan power based on a change in the
vital temperature. When the vital temperature decreases, the fan
power is reduced to slow the fan rotational speed, and when the
vital temperature increases, the fan power is increased to increase
the fan rotational speed.
[0011] According to the claimed invention, the method can further
increase the fan power by a first power when the vital temperature
increases by a first temperature, and decrease the fan power by a
second power when the vital temperature decreases by a second
temperature. The first power is directly proportional to the first
temperature, and the second power is directly proportional to the
second temperature.
[0012] According to the claimed invention, the cooling fans
controlled include a CPU cooling fan, an auxiliary cooling fan, or
a power supply cooling fan, and the vital temperature is obtained
from an on-die thermal monitoring transistor of the CPU.
[0013] A cooling system device according to the claimed invention
includes at least a cooling fan, a fan input-output module for
transmitting a control signal to the fan for controlling the
rotational speed of the fan, and a chipset interface for generating
the fan control signal based on a change in a vital temperature of
the computer system and outputting the fan control signal to the
fan input-output module. The cooling system device further includes
a controller for receiving the vital temperature and forwarding the
vital temperature to the chipset interface, and a temperature
transducer for generating the vital temperature and outputting the
vital temperature to the controller.
[0014] It is an advantage of the claimed invention that the
differential consideration of temperature, that is, the measurement
of the change in vital temperature, improves the control of the fan
speed.
[0015] It is a further advantage of the claimed invention that the
differential consideration of temperature and the corresponding
differential setting of the fan speed result in reduction in fan
speed, and thus, fan noise and power consumption.
[0016] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic diagram of a computer cooling system
according to the prior art.
[0018] FIG. 2 is a schematic diagram of a computer cooling system
according to the present invention.
[0019] FIG. 3 is a flowchart of a first method according to the
present invention.
[0020] FIG. 4 is a flowchart of a second method according to the
present invention.
[0021] FIG. 5 is a diagram of a user interface according to the
present invention.
[0022] FIG. 6 is a diagram of a fan speed setting interface of the
user interface of FIG. 5.
DETAILED DESCRIPTION
[0023] Please refer to FIG. 2 showing architecture of a cooling
system 20 for a computer according to the present invention. The
cooling system 20 includes a series of fans, of which all are
optional as long as one is provided, including a CPU fan 22, an
auxiliary (case) fan 24, and a power supply fan 26 installed in the
computer. The fans 22, 24, 26 are three pin fans, the pins being
power and ground pins for operation, and a tachometer output pin
for rotational speed measurement. The CPU fan 22 is attached to a
CPU heat sink, the auxiliary fan 24 is typically mounted inside the
computer case near vent holes, and the power supply fan 26 is
provided in the AC to DC power supply enclosure. The cooling system
20 can be applied in a wide variety of computer designs each having
different fan arrangements. It is anticipated that many such
implementations will include only the CPU fan 22, which is the most
common active cooling device for modern processors. The cooling
system further includes a fan input-output module 28 adapted to the
number and types of fans used. The fan I/O 28 outputs analog
control signals to the fans 22, 24, 26 based on digital control
signals 40 received from a chipset interface 30. As most currently
available fans require analog input, the fan I/O 28 facilitates the
analog/digital conversion between the fans 22, 24, 26 and the
chipset interface 30. The chipset interface 30 is connected to a
temperature sensor 32, such as an on-die temperature sensitive
transistor or a strategically placed thermistor, thermopile, or the
like, to measure a vital temperature of the computer system. The
sensor 32 can be located anywhere practical within the computer
system, but an on-die transistor yields the most accurate results,
and is standard on modern CPUs. The chipset interface 30 decodes
and stores the temperature signal output by the sensor 32, and
generates and outputs resulting control fan signals 40 to the fan
I/O 28. To aid operation of the chipset interface 30 a memory 34 is
provided to store relations of temperature to fan speed and other
relevant data. Finally, the cooling system 20 includes a controller
36, such as a BIOS or an operating system (such as Microsoft
Windows.TM. or Linux.TM.), for controlling the chipset interface 30
and managing the overall operation of the cooling system 20. Aside
from the auxiliary fan 24 and power supply fan 26, the hardware
components of the cooling system 20 are typically provided on the
computer motherboard.
[0024] In the preferred embodiment, the chipset interface 30 is
software code executed by the processor of the computer system.
That is, the chipset interface 30 comprises a set of instructions
for the CPU to execute. In other embodiments, the chipset interface
could include hardware instructions in a ROM, flash memory, or
similar device. In practical applications, whether the chipset
interface 30 is realized by software or hardware is determined by a
skilled designer.
[0025] According to the preferred embodiment, the memory 34 stores
the relationships between the vital temperature and fan speed for
each of the fans 22, 24, 26. These relationships can be stored in
tabular form or as computational algorithms in the memory 34. The
chipset interface 30 then references a selected tabulated data or
algorithm for the selected fan and generates the fan control signal
40 accordingly. In addition, the memory 34 is used by the chipset
interface 30 for temporary storage of data required by processing
operations. In practical application, the memory 34 is a hard disk,
RAM, or BIOS memory of the computer system.
[0026] Operations of the fan I/O 28, the fans 22, 24, 26, and the
sensor 32 are well known in the art, and one of ordinary skill in
the art would be able to find ample references, in addition to
those mentioned here, relating specific circuits and procedures for
specific component selections. Thus, a variety temperature sensors
and fans can be used, and the present invention is not limited by
such design choices.
[0027] As described above, the chipset interface 30 generates the
fan control signal 40. Depending on the number and type of fans
used, the fan control signal 40 can have several encoded
components. For example, if the CPU fan 22 and the auxiliary fan 24
are used, the fan control signal 40 comprises a CPU fan control
segment and an auxiliary fan control segment, separated by time
division, digital encoding, or a similar encoding scheme.
[0028] The chipset interface 30 determines and sets the fan speeds
according to changes of the output of the temperature sensor 32.
Before setting fan speeds, the chipset interface 30 measures the
maximum RPM of each connected fan 22, 24, 26. This allows the
chipset interface 30 to prevent over or under powering the fan, and
to perform calculations and produce output as percentages of
maximum fan speed. FIG. 3 illustrates a flowchart of a first method
50 performed by the chipset interface 30 according to the present
invention. First, the sensor 32 outputs the measured temperature to
the interface chipset 30. The tachometer of a fan 22, 24, 26
outputs a fan speed measurement to the interface chipset 30, so
that when the chipset interface 30 modifies the fan speed it can
ensure that the fan is not overpowered or stalled. Then, the
chipset interface 30 calculates a level of a change in temperature,
.DELTA.t, of the sensor 32 and compares the change with thresholds
t1, t2, etc. Finally, the chipset interface 30 selects a
corresponding change in fan speed, P1, P2, etc, and effects this
change in fan speed by outputting a corresponding fan signal 40.
The values and quantities of the change in temperature thresholds
t1, t2, etc and the corresponding change in fan speeds P1, P2, etc
can be selected referencing sound design principles. This procedure
can be performed for all fans in the system, either sequentially or
simultaneously. As a result, a measured change in vital temperature
of the CPU or preferred measuring point is converted into a change
in fan speed of a desired fan.
[0029] FIG. 4 shows a flowchart of a second method 60 according to
the present invention. As in the first method 50, the sensor 32 and
the tachometer of a fan 22, 24, 26 respectively output a
temperature and a fan speed measurement to the chipset interface
30. Then, the chipset interface 30 determines if the vital
temperature of the computer system has increased, decreased, or
remained unchanged. The second method 60 further introduces a set
temperature threshold for enhanced control, the set temperature
being set based on design parameters of the computer system, such
as heat sink quality, fan cooling effect, and normal processor
activity. When the temperature increases, the chipset interface 30
compares the temperature level to the set temperature, increasing
the fan speed when the temperature is above the set temperature and
otherwise maintaining the fan speed. When the temperature
decreases, the chipset interface 30 reduces the fan speed. When
there is no significant change in the vital temperature, the
chipset interface 30 maintains the fan speed if the temperature is
above the set temperature and reduces the fan speed when the
temperature is below the set temperature. The threshold determining
a temperature change and the levels of fan speed change effected
are selected based on the specific computer system design.
Naturally, the above procedure shown in FIG. 4 can be performed
sequentially or simultaneously for all fans in the system.
[0030] A sample of pseudo-code that realizes the second method 60
shown in FIG. 4 is given below:
[0031] Ti=current CPU temperature
[0032] Ti-1=previous CPU temperature
[0033] Tset=set temperature
[0034] PWM=fan speed as percentage of full speed
[0035] If Ti>Ti-1 and Ti>=Tset then
[0036] PWM=PWM+30%
[0037] (limit PWM to 100%)
[0038] ElseIf Ti>Ti-1 and Ti<Tset then
[0039] PWM=PWM
[0040] ElseIf Ti<Ti-1 then
[0041] PWM=PWM-20%
[0042] (limit PWM to 0%, or above stall speed)
[0043] ElseIf Ti=Ti-1
[0044] If Ti>Tset then
[0045] PWM=PWM
[0046] Else
[0047] PWM=PWM-20%
[0048] (limit PWM to 0%, or above stall speed)
[0049] Endif
[0050] Endif
[0051] To complement the second method 60 described above,
catch-all fan speed levels are established to insure that at
certain temperature levels relative to the set temperature, certain
minimum fan speeds are maintained. These fan speed levels serve as
insurance against the unpredictability of processor loading and
consequent heat generation. A sample of pseudo-code for this is
given below:
[0052] Tc=a critical operating temperature if the computer
system
[0053] If Ti-Tset>0 and PWM<10% then PWM=10%
[0054] If Ti-Tset>3 and PWM<50% then PWM=50%
[0055] If Ti-Tset>6 and PWM<100% then PWM=100%
[0056] If Ti>=Tc then PWM=100%
[0057] For example, from the above, when the measured vital
temperature is above the set temperature by 3 degrees, the fan
speed is automatically set to half of full speed. In addition, if
the temperature goes above the critical temperature, which is
typically indicated by CPU manufacturers as a maximum operating
temperature of the CPU before any CPU fail-safes initiate, the fan
is automatically run at full speed. The incorporation of set fan
speeds for set temperature ranges acts to supplement the
differential fan speed control of the second method 60 of the
present invention.
[0058] When computer system is being booted, is in the power-on
self-test (POST) state, or is otherwise not under control of a
conventional operating system, the present invention is performed
by the BIOS. That is, the chipset interface 30 is realized with
BIOS code executable by a BIOS processor under control of the
controller (BIOS) 36, and the memory 34 is a BIOS memory accessible
by the BIOS processor. It should be noted that even though the
computer is booting or in the POST state, it can execute specially
developed applications and therefore can generate significant
amounts of heat. In this way, thermal management can be
accomplished independent of operating system.
[0059] When the computer system is under control of an operating
system, the present invention is performed by code executable under
the operating system. The chipset interface 30 is realized with
operating system executable code, such as code written and complied
according to the C programming language. The memory 34 is a RAM or
hard disk of the computer system, accessible by the operating
system. Any application incorporating the present invention in both
the operating system environment and the BIOS thus has two
independent instruction sets and two separate memory elements.
While this duality has advantages, such as redundancy and
robustness, harmonization of the chipset interface code 30 and
physical memory 34 is also possible. As such, thermal management
can be accomplished under the operating system and under both the
operating system and the BIOS of the computer.
[0060] Aside from one or both of the present invention temperature
control methods 50, 60 described previously, the chipset interface
30 can also be programmed with well-known methods. The chipset
interface 30 is then capable of switching between such well-known
methods and the methods 50, 60 according to the present invention.
Examples of such well-known methods include the fixed fan speed
control and multiple level fan speed control methods, with detailed
descriptions being given in the description of the prior art. A
suitable user interface or automatic control system is provided to
the chipset interface 30 to realize switching between several
temperature control schemes.
[0061] As mentioned, the chipset interface 30 controls the speed of
the power supply fan 26 according the temperature measured by the
senor 32. This reduces power consumption and fan noise by reducing
an unnecessarily high speed of the power supply fan 26. When used
to control the power supply fan 26, the method 50, 60 is set to
consider heat generated by the power supply in addition to heat
generated by the CPU. This is realized by precisely setting
parameters, such as thresholds t1, t2 and fan speed increments P1,
P2. That is, automatic shutdown of the power supply due to
overheating as a result of low fan speed, initiated by a
temperature sensitive switch or similar device, is prevented.
[0062] According to the present invention, the chipset interface 30
can be provided with a user interface to allow for user
configuration of temperature control. Of interest to a user is
selecting the specific temperature control method, configuring
parameters influencing the selected method, and monitoring
temperature and fan speed output. FIG. 5 illustrates such a user
interface 70 according to the present invention. The user interface
70 is realized with a window in the operating system of the
computer, and a similar user interface can be provided in the BIOS.
An option to select between four modes of fan speed control is
provided in the region 72. Further, panels 74 allow the user to
access and configure different aspects of fan control, such as
voltage settings and graphical output, and control buttons 76
provide a means of control, such as saving and exiting commands.
When the user desires to configure fan speed control, they are
presented with a window such as a fan speed setting interface 80 of
FIG. 6. The fan speed setting interface 80 comprises several slider
bars for setting fan speed corresponding to configurable
temperatures levels for each fan included in the cooling system,
realizing a configurable multilevel fan speed control system.
Control of other cooling algorithms can be provided by similar
windows. With user interfaces 70 and 80 and other similar
interfaces, a user can finely tune the present invention cooling
system according to his or her specific needs.
[0063] In contrast to the prior art, the present invention provides
a cooling system and methods for operation thereof that minimize
fan noise while reducing power and maintaining allowable operating
temperatures. Specifically, the present invention provides methods
that relate changes in computer system vital temperature to changes
in fan speed of one or more cooling fans, including a power supply
cooling fan. A chipset interface is provided to measure the changes
in vital temperature, calculate the corresponding fan speeds, and
output a control signal to achieve these fan speeds. Thus, the
preset invention realizes improvements in power consumption and fan
noise.
[0064] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *