Patent Publication Number: US-2013230397-A1

Title: Fan Control Device and Fan Control Method and Cooling System Thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fan control device and fan control method and cooling system thereof, and more particularly, to a fan control device and fan control method and cooling system thereof capable of increasing a maximum operable rotating speed of the fan under a high elevation environment, to enhance fan efficiency and reduce cost. 
     2. Description of the Prior Art 
     An air cooling system is commonly used in an electronic package cooling system for considerations of cost and reliability. However, since the cooling capability of the air cooling system is highly related to the air density (the air cooling system performs cooling by a heat convection of air molecules), compared the cooling capability of the air cooling system of an environment of low elevation and high air density, with that under an environment of high elevation (e.g. above 3000-4000 feet) and low air density decreases significantly. Therefore, other than cooling operations under the low elevation, design of cooling operations of the current cooling system under the high elevation should also be considered, to meet practical requirements, i.e. the design of the current cooling system needs to consider drawbacks of the reduced cooling capability and the reduced heat convection capability due to the reduced air density 
     In such a situation, the conventional cooling system generally increases the number of fans, or is over-designed with a fan of higher performance (i.e. compared with a fan generally utilized for the low elevation environment, the fan of higher performance can be drove with higher current to achieve higher rotating speed for cooling), to meet the cooling requirements under the high elevation environment, or even reduces system performance to reduce heat, to adapt to performance loss of the fan under the high elevation environment. 
     However, increasing the number of the fans for the high elevation requirements may increase the cost, and over-designing the fan with higher performance may increase the cost and can not make full use of the fan of higher performance under the low elevation environment, which causes waste. Thus, there is a need for improvement of the prior art. 
     SUMMARY OF THE INVENTION 
     It is therefore an objective of the present invention to provide a fan control device and fan control method and cooling system thereof capable of increasing a maximum operable rotating speed of the fan under a high elevation environment, to enhance fan efficiency and reduce the fan cost. 
     The present invention discloses a fan control device for controlling a fan. The fan control device includes a barometer, for measuring an atmospheric pressure of an operating environment of the fan; and a maximum rotating speed setting unit, for setting a maximum operable rotating speed of the fan according to the atmospheric pressure. 
     The present invention further discloses a fan control method for controlling a fan. The fan control method includes measuring an atmospheric pressure of an operating environment of the fan; and setting a maximum operable rotating speed of the fan according to the atmospheric pressure. 
     The present invention further discloses a cooling system. The cooling system includes a fan; and a fan control device for controlling the fan. The fan control device includes a barometer, for measuring an atmospheric pressure of an operating environment of the fan; and a maximum rotating speed setting unit, for setting a maximum operable rotating speed of the fan according to the atmospheric pressure. 
     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 
         FIG. 1  is a schematic diagram of a cooling system according to an embodiment of the present invention. 
         FIG. 2  is a detailed schematic diagram of a fan control process according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 , which is a schematic diagram of a cooling system  10  according to an embodiment of the present invention. As shown in  FIG. 1 , the cooling system  10  includes a fan  102  and a fan control device  104 . The fan control device  104  can control the fan  102 , and include a barometer  106  and a maximum rotating speed setting unit  108 . In short, the barometer  106  can measure an atmospheric pressure AP of an operating environment of the fan  102 , and the maximum rotating speed setting unit  108  can set a maximum operable rotating speed MORS of the fan  102  according to the atmospheric pressure AP. 
     Since air density is low under a high elevation environment, an air resistance for the fan  102  is reduced as well, and the fan  102  can have a higher rotating speed when the fan  102  consuming the same energy as under a low elevation environment. In such a situation, the fan control device  104  can set the maximum operable rotating speed MORS of the fan  102  as a predefined low elevation maximum operable rotating speed DLMORS which the fan  102  can tolerate under a low elevation environment (i.e. a rotating speed achieved by the fan  102  when receiving a maximum tolerable energy under the low elevation environment), and the fan control device  104  sets the maximum operable rotating speed MORS of the fan  102  as a high elevation maximum operable rotating speed HMORS which the fan  102  can sustain under the high elevation environment (i.e. the rotating speed achieved by the fan  102  when receiving the maximum sustainable energy under the high elevation environment), wherein the high elevation maximum operable rotating speed HMORS is greater than the predefined low elevation maximum operable rotating speed DLMORS. As a result, since the fan control device  104  can measure the atmospheric pressure AP of the operating environment of the fan  102 , and increase the maximum operable rotating speed MORS of the fan  102  to enhance performance when under the high elevation environment, the present invention does not need to increase the number of fans or over-design a fan with higher performance, so as to reduce cost. 
     Please refer to  FIG. 2 , which is a detailed schematic diagram of the fan control process  20  according to an embodiment of the present invention. The fan control process  20  is utilized in the fan control device  104 , to set the maximum operable rotating speed MORS of the fan  102 . The fan control process  20  includes following steps: 
     Step  200 : Start. 
     Step  202 : Measure the atmospheric pressure AP of the operating environment of the fan  102 . If the atmospheric pressure AP is greater than a predefined atmospheric pressure DAP, go to Step  204 ; otherwise, go to Step  206 , wherein an operating current of the fan  102  is an operating current Ia when the fan  102  is driven. 
     Step  204 : Determine that the fan  102  operates in a low elevation environment, and set the maximum operable rotating speed MORS of the fan  102  as the predefined low elevation maximum operable rotating speed DLMORS, wherein the operating current Ia of the fan  102  is a maximum operating current Id when the fan  102  is driven in the predefined low elevation maximum operable rotating speed DLMORS. 
     Step  206 : Determine that the fan  102  operates in a high elevation environment, and increase the maximum operable rotating speed MORS of the fan  102 . 
     Step  208 : Determine whether the operating current Ia is less than the maximum operating current Id. If yes, go to Step  206 ; otherwise, go to Step  210 . 
     Step  210 : Set the maximum operable rotating speed MORS of the fan  102  as the high elevation maximum operable rotating speed HMORS when the operating current Ia of the fan  102  is equal to the maximum operating current Id, wherein the high elevation maximum operable rotating speed HMORS is the rotating speed of the fan  102  driven with the maximum operating current Id. 
     According to the fan control process  20 , the fan control device  104  measures the atmospheric pressure AP of the operating environment of the fan  102  first, and if the atmospheric pressure AP is greater than the predefined atmospheric pressure DAP, the fan control device  104  determines that the fan  102  operates in the low elevation environment, and thus sets the maximum operable rotating speed MORS of the fan  102  as the predefined low elevation maximum operable rotating speed DLMORS, and the predefined low elevation maximum operable rotating speed DLMORS is the rotating speed of the fan  102  when the operating current Ia of the fan  102  is the maximum operating current Id (i.e. the maximum tolerable energy of the fan  102 ). As a result, since the maximum operable rotating speed MORS of the fan  102  under the low elevation environment can be set as the rotating speed achieved by the fan  102  when receiving the maximum tolerable energy, the performance of the fan  102  is fully utilized. 
     On the other hand, if the atmospheric pressure AP is less than the predefined atmospheric pressure DAP, the fan control device  104  determines that the fan  102  operates in the high elevation environment, and thus sets the maximum operable rotating speed MORS of the fan  102  to be greater than the predefined low elevation maximum operable rotating speed DLMORS (since the air density is low under the high elevation environment, the fan  102  can achieve a higher rotating speed with the same maximum tolerable energy). At this moment, the fan control device  104  can increase the maximum operable rotating speed MORS of the fan  102  first, and determine whether the corresponding operating current Ia is less than the maximum operating current Id. If the operating current Ia is less than the maximum operating current Id, the fan control device  104  continues to increase the maximum operable rotating speed MORS of the fan  102  until the operating current Ia of the fan  102  is equal to the maximum operating current Id, and the maximum rotating speed setting unit  108  sets the maximum operable rotating speed MORS of the fan  102  as the high elevation maximum operable rotating speed HMORS, wherein the high elevation maximum operable rotating speed HMORS is the rotating speed of the fan  102  when the maximum rotating speed setting unit  108  drives the fan  102  with the maximum operating current Id (i.e. the maximum tolerable energy of the fan  102 ) under the high elevation environment. In such a situation, after deriving the high elevation maximum operable rotating speed HMORS by above operations, in a next operation, if the fan control device  104  measures the atmospheric pressure AP is less than the predefined atmospheric pressure DAP again and determines that the fan  102  operates in the high elevation environment again, the maximum operable rotating speed MORS can be directly set as the high elevation maximum operable rotating speed HMORS, to reduce a time consumed by loop determination, and enhance the fan efficiency. As a result, since the air density is low under the high elevation environment, the maximum operable rotating speed MORS of the fan  102  can be increased and set as the rotating speed achieved by the fan  102  when receiving the maximum tolerable energy, and thus performance of the fan  102  adapted to the low elevation environment can be fully utilized, to meet requirement of the high elevation environment (i.e. the performance of the fan  102  can be fully utilized under the low elevation environment or high elevation environment) without utilizing the fan of higher performance as the prior art. 
     Noticeably, the main spirit of the present invention is to measure the atmospheric pressure AP of the operating environment of the fan  102 , to increase the maximum operable rotating speed MORS of the fan  102  when the fan  102  is under the high elevation environment, to enhance the performance, so as to reduce cost without increasing the number of the fans or over-designing the fan with higher performance. Those skilled in the art can make modifications or alterations accordingly. For example, the above embodiment sets the maximum operable rotating speed MORS of the fan  102  after determining the fan  102  operates under the low elevation environment or high elevation environment with the barometer  106 . In other embodiments, the fan control device  104  does not include the barometer  106 , and increases the maximum operable rotating speed MORS of the fan  102  according to whether the operating current Ia is less than the maximum operating current Id (i.e. the maximum operable rotating speed MORS is the rotating speed corresponding to the maximum operating current Id in different environments), but the operating current Ia and the maximum operating current Id are compared continuously, causing system unstable. 
     In the prior art, increasing the number of the fans for requirement the high elevation environment may increase cost, and over-designing the fan with higher performance may increase the cost and not fully utilize the fan under the low elevation environment, causing waste. In comparison, the present invention can measure the atmospheric pressure AP of the operating environment of the fan  102 , to increase the maximum operable rotating speed MORS of the fan  102  when under the high elevation environment, to enhance performance, and thus reducing cost without increasing the number of the fans or over-designing the fan with higher performance. 
     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.