Abstract:
An air fan rotation speed control method and a structure thereof aim to provide an automatic control mode and a manual control mode at the same time to control rotation speed regulation of an air fan to achieve instant heat dissipation for an environment and reduce temperature rising of the environment efficiently. The present invention has a rotation speed determination mechanism that adopts the higher rotation speed request at a higher priority to regulate the rotation speed of the air fan in either control mode. Hence the temperature of the environment can be reduced at the higher rotation speed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an air fan rotation speed control method and a structure thereof, and more particularly to a method and structure that have an automatic control mode and a manual control mode at the same time to regulate and control air fan rotation speed to dissipate heat instantly and reduce temperature rising in an environment. 
   BACKGROUND OF THE INVENTION 
   With the functional demands of the computer system grow constantly, especially in the environment where the technologies of the Internet and multimedia advance rapidly, the performance of electronic devices increase. The heat energy generated in the electronic device also increases significantly. As the computer system usually has a closed interior space, and the size and installation space are constrained, as a result, the computer system often encounters machine crash due to overheating. 
   At present, the computer system (or power supply of the computer system) generally uses an air fan to channel external cooling airflow into the computer system or dispel the interior heated airflow outside to dissipate heat and reduce temperature. In response to different temperature rising conditions in various operating conditions of the computer system, regulating the rotation speed of the air fan usually adopts a manual control mode or an automatic control mode. The automatic control mode generally includes a timing mode, a temperature detection mode or a power use mode that are based on parameters attributable to increasing of the temperature in the computer system to regulate the air fan rotation speed. The automatic control mode controls the air fan to rotate at different speeds under different parameters. The manual control mode inputs air fan rotation speed regulation commands through an external control button, or a communication means such as I2C, RS232, RS384 and the like. In an industrial computer array system, a remote control method is usually adopted to monitor the operation of the computer system. If a temperature rising condition of the computer system can be predicted, the control method can directly set and regulate the air fan at a desired rotation speed in advance. Then the air fan can reach or maintain the desired rotation speed earlier to keep the computer system operating in a stable temperature condition. 
   The two modes mentioned above are used independently in the present applications. Each has its advantages and drawbacks. However, as the present computer system becomes more powerful, integrating the two modes becomes necessary. For instance, while the manual control mode can set in advance the air fan rotation speed, it frequently happens that the communication network is interrupted or damaged, but the air fan still rotates at the preset speed. In the event that the temperature rises and exceeds the heat dissipation capability of the air fan, the computer system could be down and the air fan becomes dysfunctional. 
   SUMMARY OF THE INVENTION 
   Therefore the primary object of the present invention is to solve the aforesaid disadvantages. The present invention provides an automatic control mode and a manual control mode at the same time to regulate and control the rotation speed of an air fan to dissipate heat instantly and reduce temperature rising in an environment. The invention has a rotation speed determination mechanism to set a higher priority to regulate the air fan rotating at a higher speed in either control mode, so that better heat dissipation can be achieved in the environment at the higher rotation speed to reduce the temperature. 
   The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a flow chart of the control method of the present invention. 
       FIG. 2  is a schematic circuit block diagram of the control structure of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please refer to  FIG. 1  for the flow chart of the control method of the present invention. The method and structure of the present invention is adopted for use on an air fan in a computer system or a power supply to channel airflow to dissipate heat and reduce temperature. The control method includes: 
   setting an air fan control mode  10 : the present invention includes an air fan rotation speed control system which has an automatic control mode to detect heat dissipating conditions of an environment and output a speed regulation signal to regulate air fan rotation speed, and a manual control mode to execute an air fan rotation speed regulation command to regulate the air fan rotation speed. The automatic control mode may be a timing mode, a temperature detection mode, a power use mode that affects temperature rising condition of the environment, or a combination of the aforesaid modes to control air fan rotation speed. The automatic control mode is implemented through an external control button, or a communication means such as I2C, RS232, RS384 to input the air fan rotation speed regulation command; and 
   selecting an air fan control mode  20 : the present invention provides a determination mechanism. Under the manual control mode in a condition not executing the air fan rotation speed regulation command, the rotation speed control system controls the air fan rotation speed through the automatic control mode; under the manual control mode in a condition of executing the air fan rotation speed regulation command, if the regulated rotation speed through the regulation command is higher than the regulated rotation speed under the automatic control mode, the manual control mode is enforced to be executed. If the regulated rotation speed through the regulation command is lower than the regulated rotation speed under the automatic control mode, the regulated rotation speed under the automatic control mode is maintained. 
   Refer to the embodiment shown in  FIG. 1 , the selecting an air fan control mode  20  may further include: 
   providing a switch mode  21 : in normal conditions, either the automatic control mode or manual control mode may be maintained. When a new air fan rotation speed value is generated, another control mode is switched. Of course, operators can preset the air fan to rotate at a selected rotation speed through the manual control mode; 
   recording the air fan rotation speed value  22 : in either control mode, the present invention provides a memory mechanism to record the air fan rotation speed value under the control mode of the preceding step. The recorded air fan rotation speed value becomes the air fan rotation speed base value of the succeeding steps; 
   determining air fan rotation speed value  23 : when the switch mode is changed to another control mode, or temperature rising condition changes due to heat dissipation environment, the operators can input a new air fan rotation speed regulation command in the manual control mode, or the automatic control mode can detect changes of heat energy in the environment to output a speed regulation signal, namely when a new air fan rotation speed value is generated, the new air fan rotation speed value will be compared with the original recorded air fan rotation speed value; 
   updating the air fan rotation speed value record  24 : after comparing the new air fan rotation speed value with the original recorded air fan rotation speed value, a higher air fan rotation speed value is retrieved to update the air fan rotation speed value record, and return to the preceding step. It is to be noted that if the step of providing a switch mode  21  is skipped, the air fan rotation speed can be regulated by a single control mode. Then the step of determining air fan rotation speed value  23  also may be omitted. Take the automatic control mode as an example, the air fan can monitor itself and alter the rotation speed according to temperature rising condition of the environment without comparing with the recorded air fan rotation speed value, so that the rotation speed can be reduced in response to environmental requirements. Namely, the present invention aims to be implemented in a condition in which the manual control mode and the automatic control mode can coexist. Only when the rotation speed value demanded by the automatic control mode is higher than the rotation speed value demanded by the manual control mode will the step of determining air fan rotation speed value  23  be executed. When there is no dual-mode coexisting signal, a single control mode operation is maintained. 
   Refer to  FIG. 2  for a circuit block diagram of an embodiment of the present invention that illustrates a structure to control air fan rotation speed. The structure mainly includes an air fan driving unit  35  to receive a rotation speed signal to drive an air fan  36  to rotate. In this embodiment, an automatic control unit  33  and a manual control unit  34  are provided and coexist. The automatic control unit  33  detects the temperature rising condition of an environment and gets a speed regulation signal. The automatic control unit  33  may be a timer, a temperature detector, a power detector, or a combination thereof. The manual control unit  34  inputs an air fan rotation speed regulation command in response to the temperature rising condition of the environment. The manual control unit  34  controls through an external control button or a communication means such as I2C, RS232, RS384 or the like. In addition, the present invention further includes a control unit  31  which receives the speed regulation signal from the automatic control unit  33  or air fan rotation speed regulation command from the manual control unit  34 . The control unit  31  further has a switch unit  32  which has a rotation speed comparing level in order to switch the signal inputted to the control unit  31  to the speed regulation signal or the air fan rotation speed regulation command. A higher air fan rotation speed value among the two becomes the rotation speed signal outputted by the control unit  31  to the air fan driving unit  35 . 
   By means of the present invention, operators can regulate the air fan rotation speed faster in the manual control mode according to heat dissipation requirement of the environment, or reduce the air fan rotation speed in the manual control mode in response to the noise requirement of the environment. In the event that the manual control mode is suspended, under the determination mechanism of the present invention, if the automatic control mode detects that the temperature rises which could become harmful to computer system operation, a higher rotation speed regulation value is issued to replace the existing lower rotation speed under the manual control mode. Hence the computer system can function in a stable manner with the air fan operating in a desired heat dissipation condition. 
   While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.