Patent Publication Number: US-2007116577-A1

Title: Fan system and seriate starting module and delayed starting unit thereof

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 094140585 filed in Taiwan, Republic of China on Nov. 18, 2005, the entire contents of which are hereby incorporated by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      The invention relates to a fan system and a seriate starting module and a delayed starting unit thereof, and, in particular, to a fan system having a plurality of fan modules, and a seriate starting module and a delayed starting unit of the fan system.  
      2. Related Art  
      Generally speaking, a large electronic system is always equipped with a fan system to ensure that the electronic system can be kept at the normal working temperature such that the electronic system can operate normally.  
       FIG. 1  is a schematic illustration showing a conventional fan system  1  disposed in an electronic system (not shown). The fan system  1  receives an input voltage V in  from exterior to serve as an operation voltage. The fan system  1  mainly has a starting module  11  and a plurality of fan modules  12   a  to  12   n . After the starting module  11  receives the input voltage V in , the fan modules  12   a  to  12   n  are started simultaneously to dissipate the heat. However, when the fan modules  12   a  to  12   n  are started simultaneously, an extremely large start-up current and inrush current are generated at the moment of starting. Thus, the electronic system or the fan system  1  may crash or have unpredictable malfunction, or even the electronic system or the fan system  1  may be damaged.  
      As shown in  FIG. 2 , another conventional fan system  1 ′ has a plurality of starting modules  11   a  to  11   n  corresponding to the fan modules  12   a  to  12   n  so as to start the fan modules  12   a  to  12   n , respectively.  
      In view of the above-mentioned problems, the prior art adopts an analog starting control chip for starting the fan modules  12   a  to  12   n  in sequential, or a software module to control the starting sequence of the fan modules  12   a  to  12   n . Thus, the prior art provides a protection mechanism for respectively starting the fan modules  12   a  to  12   n  at different time instants so as to avoid the malfunction caused when the fan modules  12   a  to  12   n  are simultaneously started. However, the analog starting control chip has a high price, and the software module has a complicated architecture. Thus, the overall manufacturing cost of the conventional fan system  1  is too high. In addition, the analog starting control chip only can delay the starting time of each of the fan modules  12   a  to  12   n  and cannot provide the function of soft-start.  
      Thus, it is an important subject of the invention to provide a fan system and a seriate starting module and a delayed starting unit thereof to overcome the above-mentioned problems.  
     SUMMARY OF THE INVENTION  
      In view of the foregoing, the invention is to provide a fan system and a seriate starting module and a delayed starting unit thereof for starting a plurality of fan modules at different time instants in a seriate manner so as to avoid the malfunction caused when the fan modules are started simultaneously.  
      In addition, the invention is also to provide a fan system and a seriate starting module and a delayed starting unit thereof having the resetting effect to discharge the residual charges in the fan system and thus avoid the malfunction.  
      To achieve the above, a fan system of the invention is for receiving an input voltage from exterior. The fan system includes a first fan module, a second fan module and a seriate starting module. The seriate starting module, which is electrically connected with the first fan module and the second fan module, receives the input voltage, starts the first fan module according to the input voltage, and starts the second fan module according to the input voltage after the first fan module is started for a predetermined time.  
      Furthermore, the invention also discloses a method of resetting a delaying circuit, which is coupled with an input voltage from exterior and has a capacitor and a switch element. The switch element receives the input voltage and is electrically connected with the capacitor and grounded. The method includes the steps of: separating the delaying circuit from the input voltage, turning on the switch element, and forming a discharge path from the capacitor to the switch element so as to perform a discharging operation.  
      As mentioned above, the fan system and the seriate starting module and the delayed starting unit thereof according to the invention can sequentially start a plurality of fan modules at different time instants so as to avoid the malfunction caused by the extremely large start-up current and inrush current, which are generated by instantaneously starting the fan modules. The fan modules are started in a time-sharing manner to ensure that the fan system can operate normally, prevent the electronic system and the fan system from being damaged, and replace the analog starting control chip to reduce the overall manufacturing cost. In addition, the invention further possesses the reset function of discharging the charges remained in the fan system so as to prevent the malfunction from occurring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein:  
       FIG. 1  is a schematic illustration showing a conventional fan system;  
       FIG. 2  is a schematic illustration showing another conventional fan system;  
       FIG. 3  is a schematic illustration showing a fan system according to a preferred embodiment of the invention; and  
       FIG. 4  is a circuit diagram showing a fan system according to the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.  
       FIG. 3  is a schematic illustration showing a fan system  2  according to a preferred embodiment of the invention. As shown in  FIG. 3 , the fan system  2  may be applied to an electronic system (not shown) in order to dissipate heat. The fan system  2  receives an input voltage  91  from exterior to serve as an operation voltage. The input voltage  91  may be supplied from the electronic system. The fan system  2  includes a first fan module  21 , a second fan module  22  and a seriate starting module  23 . Each of the first fan module  21  and the second fan module  22  has a fan. Of course, the user may dispose a plurality of fans in each of the first fan module  21  and the second fan module  22  according to the heat dissipating requirement so as to enhance the heat dissipating effect.  
      The seriate starting module  23  includes a starting unit  231  and a delayed starting unit  232 . The starting unit  231  electrically connected with the first fan module  21  receives the input voltage  91  and starts the first fan module  21  according to the input voltage  91 . The delayed starting unit  232  includes a starting circuit  233  and a delaying circuit  234 . The starting circuit  233 , which is electrically connected between the second fan module  22  and the delaying circuit  234 , receives the input voltage  91 . The delaying circuit  234  controls the starting circuit  233  to start the second fan module  22  according to the input voltage  91  after the first fan module  21  is started for a predetermined time.  
      Then, the fan system  2  of this embodiment starts the second fan module  22  after the first fan module  21  is started for the predetermined time, such that the first fan module  21  and the second fan module  22  can be started at different time instants. Thus, it is possible to avoid the malfunction caused by the extremely large start-up current and inrush current, which are generated when the first fan module  21  and the second fan module  22  are started simultaneously.  
      In addition,  FIG. 4  is a circuit diagram showing a fan system according to the preferred embodiment of the invention. Referring to  FIG. 4 , the delayed starting unit  232  includes a starting circuit  233  and a delaying circuit  234 . The starting circuit  233  has a plurality of diodes D 1  to D 4 , a plurality of resistors R 1  and R 2 , a first switch element Q 1 , a second switch element Q 2 , a plurality of capacitors C 1  and C 5 . The second switch element Q 2  electrically connected with the first switch element Q 1  through the diode D 3  controls the first switch element Q 1 . In addition, the delaying circuit  234  is electrically connected with the first switch element Q 1  through the diodes D 1 , D 2  and is further electrically connected with the second switch element Q 2  through the resistor R 9 . To be noted, the dispositions of the diodes D 1 , D 2  and the resistor R 9  are used to make the starting circuit  233  more stable, and are omissible.  
      Each of the first switch element Q 1  and the second switch element Q 2  may be a transistor or any other electronic element with the switch function. In this embodiment, the first switch element Q 1  is a PMOS transistor, and the second switch element Q 2  is an NMOS transistor. In addition, the diodes D 1  and D 2  are connected in parallel. Each of the diodes D 1  and D 2  has a first terminal for receiving the input voltage  91 . In this embodiment, each of the diodes D 1  and D 2  may be a Schottky diode for avoiding the reverse current. One terminal of the resistor R 1  is electrically connected with a second terminal of each of the diodes D 1  and D 2 .  
      A source S of the first switch element Q 1  is electrically connected with the second terminals of the diodes D 1  and D 2  to receive the input voltage  91 . A drain D of the first switch element Q 1  is electrically connected with the second fan module  22  and is used to start the second fan module  22 . A drain D of the second switch element Q 2  is electrically connected with the second terminals of the diodes D 1  and D 2  through the resistor R 1 . The drain D of the second switch element Q 2  is further electrically connected with a gate G of the first switch element Q 1  through the diode D 3 . A gate G of the second switch element Q 2  is electrically connected with the delaying circuit  234  through the resistor R 9 .  
      A first terminal of the diode D 3  is electrically connected with the drain D of the second switch element Q 2 . A second terminal of the diode D 3  is electrically connected with the gate G of the first switch element Q 1 . A first terminal of the diode D 4  is electrically connected with the source S of the first switch element Q 1 . A second terminal of the diode D 4  is electrically connected with the second terminal of the diode D 3 . A first terminal of the capacitor C 1  is electrically connected with the source S of the first switch element Q 1 , and a second terminal of the capacitor C 1  is electrically connected with a first terminal of the resistor R 2 . A second terminal of the resistor R 2  is grounded.  
      The delaying circuit  234  includes a third switch element Q 3 , a fourth switch element Q 4 , a fifth switch element Q 5 , a sixth switch element Q 6 , a comparator U 1 , a plurality of resistors R 3  to R 8  and R 12  to R 14 , at least one capacitor C 2  and at least one diode D 5 . Each of the third switch element Q 3 , the fourth switch element Q 4 , the fifth switch element Q 5  and the sixth switch element Q 6  may be a transistor or any other electronic element with the switch function. In this embodiment, each of the third switch element Q 3 , the fifth switch element Q 5  and the sixth switch element Q 6  is an NPN transistor, and the fourth switch element Q 4  is a PNP transistor.  
      A base B of the third switch element Q 3  electrically connected with a first terminal of the resistor R 3  receives the input voltage  91 . A collector C of the third switch element Q 3  is electrically connected with the diodes D 1  and D 2  through a resistor R 5 . An emitter E of the third switch element Q 3  and a resistor R 4  are grounded.  
      A base B of the fourth switch element Q 4  is electrically connected with the collector C of the third switch element Q 3 . An emitter E of the fourth switch element Q 4  is connected with an external power VCC.  
      The resistor R 6  has a first terminal, which is electrically connected with a collector C of the fourth switch element Q 4 , and a second terminal.  
      The capacitor C 2  has a first terminal, which is electrically connected with the second terminal of the resistor R 6  through the diode D 5 , and a second terminal grounded. In addition, the capacitor C 2  starts to charge and generate a control signal V 1  at the first terminal of the capacitor C 2  when the fourth switch element Q 4  turns on.  
      The comparator U 1  has a first input terminal input 1 , a second input terminal input 2  and an output terminal output. In this embodiment, the first input terminal input 1  is a noninverting input terminal and the second input terminal input 2  is an inverting input terminal. The first input terminal input 1  is electrically connected with the second terminal of the resistor R 6 . The second input terminal input 2  is electrically connected with the resistors R 7  and R 8 , and the resistors R 7  and R 8  form a voltage-dividing circuit and provide a reference signal V ref  to the second input terminal input 2 . The output terminal output, which is electrically connected with the gate of the second switch element Q 2  through the resistor R 9 , controls the second switch element Q 2 .  
      A collector C of the fifth switch element Q 5  is electrically connected with the first terminal of the capacitor C 2 . An emitter E of the fifth switch element Q 5  is grounded. A collector C of the sixth switch element Q 6  is electrically connected with a base B of the fifth switch element Q 5 . A base B of the sixth switch element Q 6  is electrically connected with the input voltage  91  through the resistor R 12 , and an emitter E of the sixth switch element Q 6  is grounded.  
      A first terminal of the resistor R 12  receives the input voltage  91 . A second terminal of the resistor R 12  is electrically connected with a first terminal of the resistor R 13 . A second terminal of the resistor R 13  is grounded. Both of the resistors R 12  and R 13  form a voltage-dividing circuit. The base B of the sixth switch element Q 6 , which is electrically connected with the second terminal of the resistor R 12 , receives the divided input voltage. A first terminal of the resistor R 14  is electrically connected with the collector C of the sixth switch element Q 6 . A second terminal of the resistor R 14  is electrically connected with the starting unit  231 .  
      The starting unit  231  mainly includes a plurality of diodes D 6  to D 9 , a plurality of resistors R 10  and R 11 , two switch elements Q 7  and Q 8  and a plurality of capacitors C 3  and C 4 . The diodes D 6  to D 9 , the resistors R 10  and R 11 , the switch elements Q 7  and Q 8  and the capacitor C 3  have the same constructions and functions as those of the diodes D 1  to D 4 , the resistors R 1  and R 2 , the switch elements Q 1  and Q 2  and the capacitor C 1 , so the detailed descriptions thereof will be omitted. In addition, the capacitor C 4  is electrically connected with the base B of the fifth switch element Q 5  and the collector C of the sixth switch element Q 6  through the resistor R 14 .  
      The operation principle of the fan system  2  will be described in the following. First, after the seriate starting module  23  receives the input voltage  91  at a first time, the starting unit  231  and the delayed starting unit  232  simultaneously receive the input voltage  91  as the operation voltage.  
      The diodes D 6  and D 7  of the starting unit  231  receive the input voltage  91  such that the switch element Q 8  turns on and the capacitor C 3  starts to charge until the voltage value of the capacitor C 3  reaches the turn-on voltage of the switch element Q 7 . When the switch element Q 7  turns on, the first fan module  21  starts to work. In this embodiment, the charging circuit of the capacitor C 3  and the resistor R 11  enables the current flowing through the first fan module  21  to increase at a slow rate such that the effect of soft starting can be achieved.  
      The delaying circuit  234  receives the input voltage  91 , the third switch element Q 3  and the fourth switch element Q 4  turn on, and the capacitor C 2  starts to charge to generate the control signal V 1 . After the predetermined time, the voltage value of the control signal V 1  is larger than the voltage value of the reference signal V ref , and the output terminal output outputs a positive voltage value to the gate of the second switch element Q 2  to control the second switch element Q 2  of the starting circuit  233  to turn on. To be noted, the predetermined time is determined according to the charging time of the capacitor C 2  and the resistor R 6 . The user can select the different capacitor C 2  and resistor R 6  according to the to-be-delayed time so as to adjust the predetermined time. Alternatively, when the resistor R 6  is a variable resistor, adjusting the resistance of the resistor R 6  can adjust the predetermined time.  
      After the second switch element Q 2  turns on, the capacitor C 1  starts to charge. When the voltage value of the capacitor C 1  reaches the turn-on voltage of the first switch element Q 1 , the first switch element Q 1  turns on to start the second fan module  22  in a soft-starting manner.  
      In addition, the fan system  2  of this embodiment further has the reset function, and the reset method is described in the following. After the seriate starting module  23  receives the input voltage  91 , the switch elements Q 7  and Q 8  turn on, the sixth switch element Q 6  of the delaying circuit  234  turns on according to the voltage-dividing operation of the resistors R 12  and R 13 , and the capacitor C 4  starts to charge. At this time, the potential of the base B of the fifth switch element Q 5  is about zero, which means that the fifth switch element Q 5  is off. When the user removes the fan system  2  from the electronic system, that is, when the sending of the input voltage  91  is stopped, the capacitor C 4  starts to discharge, and the voltage drop generated by the resistor R 14  serves as a tum-on voltage to turn on the fifth switch element Q 5 . At this time, the capacitor C 2  can form a discharge path through the fifth switch element Q 5  so as to discharge the charges stored in the capacitor C 2  and thus achieve the reset effect. Thus, the malfunction can be avoided when the user inserts the fan system  2  back to the electronic system at the next time. Consequently, the fan system  2  of this embodiment starts the first fan module  21  and the second fan module  22  at different time instants using the seriate starting module  23  so as to achieve the effect of seriate starting and resetting. In addition, although only two fan modules are illustrated in  FIG. 4 , the number of fan modules can be adjusted according to the user&#39;s requirement.  
      In summary, the fan system and the seriate starting module and the delayed starting unit thereof according to the invention can sequentially start a plurality of fan modules at different time instants so as to avoid the malfunction caused by the extremely large start-up current and inrush current, which are generated by instantaneously starting the fan modules. The fan modules are started in a time-sharing manner to ensure that the fan system can operate normally, prevent the electronic system and the fan system from being damaged, and replace the analog starting control chip to reduce the overall manufacturing cost. In addition, the invention further possesses the reset function of discharging the charges remained in the fan system so as to prevent the malfunction from occurring.  
      Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.