Abstract:
A cooling system includes a first detection module, a second detection module, a control module connected to the first detection module and the second detection module, and a fan connected to the control module. The first detection module is used to detect a first temperature value and input a first voltage value to the control module according to the first temperature value. The second detection module is used to detect a second temperature value and input a second voltage value to the control module according to the second temperature value. The control device is used to control the fan according to a difference value between the first voltage and the second voltage.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to cooling systems, and more particularly to a cooling system for an automatic vending machine. 
         [0003]    2. Description of Related Art 
         [0004]    Automatic vending machines allow customers to buy product twenty four hours a day. The automatic vending machine often comprises a cooling device and a fan located in a bottom portion of the automatic vending machine. The cool air generated by the cooling device is transmitted to the interior of the automatic vending machine by the fan. The bottom portion of the automatic vending machine can be effectively cooled by the fan, but other portions, such as the top portion of the automatic vending machine, cannot be effectively cooled by the fan. Therefore, there is room for improvement within the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like-reference numerals designate corresponding parts throughout the several views. 
           [0006]      FIG. 1  is a schematic view of a cooling system in accordance with an embodiment. 
           [0007]      FIG. 2  is a schematic view of a power supply module of the cooling system of  FIG. 1 . 
           [0008]      FIG. 3  is a schematic view of a detecting module of the cooling system of  FIG. 1 . 
           [0009]      FIG. 4  is a schematic view of a control module of the cooling system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one”. 
         [0011]      FIGS. 1-2  illustrate a cooling system in accordance with an embodiment. The cooling system comprises a power supply module  10 , three detection modules  20 , a control module  30 , and two fans  40 . The three detection modules  20  are connected to the power supply module  10  and the control module  30 , and the two fans  40  are connected to the control module  30 . In one embodiment, the three detection modules  20  are located on different locations of a vending machine and the two fans  40  are also located on different locations of the vending machine. a first one of the three detecting modules  20  is located on a top portion of the vending mechanism, a second one of the three detecting modules  20  is located on a middle portion of the vending mechanism, and a third one of the three detecting modules  20  is located on a bottom portion of the vending mechanism. 
         [0012]    The power supply module  10  comprises a first capacitor C 1 , a second capacitor C 2 , a power source  11 , and a first sliding rheostat  12 . The first sliding rheostat  12  comprises a first connecting end  13 , a second connecting end  15 , and a first sliding end  14  located between the first connecting end  13  and the second connecting end  15 . A terminal of the power source  11  is connected to a power supply (not shown), and the power source  11  is grounded via the first capacitor C 1  and the second capacitor C 2 . The first end  13  is connected to the output end of the power source  11 , and the second end  15  is grounded. The first sliding end  14  is connected to the three detection modules  20 . In one embodiment, the resistance of the first sliding rheostat  12  is 0˜1 KΩ, the capacitance of the first capacitor C 1  is 1 Uf and substantially equal to the capacitance of the second capacitor C 2 , and the model of the power source  11  is 78L05A. 
         [0013]      FIG. 3  illustrates each detection module  20  of the cooling system in accordance with an embodiment. Each detection module  20  comprises a sensor  21 , an operational amplifier  22 , a display  23 , and a second sliding rheostat  24 . The first sliding end  14  is connected to a first node  28  via a first resistor R 1 , and the first sliding end  14  is also connected to a positive terminal of the operational amplifier  22  via a second resistor R 2 . The first node  28  is connected to a negative terminal of the operational amplifier  22  via a third resistor R 3 . A first end of the sensor  21  is connected to the positive terminal of the operational amplifier  22 , and a second end of the sensor  21  is connected to a second node  29 . 
         [0014]    The second sliding rheostat  24  comprises a third connecting end  25 , a fourth connecting end  27 , and a second sliding end  26  located between the third connecting end  25  and the fourth connecting end  26 . The third connecting end  25  is connected to the first node  28 , and the fourth connecting end  27  and the second sliding end  26  are connected to the second node  29 . A fourth resistor R 4  is connected to the first node  28  and the second node  29 . The negative terminal of the operational amplifier  22  is connected to the control module  30  and also connected to the output end of the operational amplifier  22  via a fifth resistor R 5 . The operational amplifier  22  is connected to the display  23 . In one embodiment, the sensor  21  is a temperature sensor, the resistance of the first resistor R 1  is 560 kΩ and substantially equal to the resistance of the second resistor R 2 . The resistance of the third resistor R 3  is 100 kΩ the resistance of the fourth resistor R 4  is 1 kΩ, and the resistance of the fifth resistor R 5  is 1 MΩ. 
         [0015]      FIG. 4  illustrates the control module  30  of the cooling system in accordance with an embodiment. The control module  30  comprises a first comparator  31 , a second comparator  32 , a first transistor Q 1 , and a second transistor Q 2 . A first one of the three detecting modules  20  is connected to the negative terminal of the first comparator  31 . A second one of the three detecting modules  20  is connected to the negative terminal of the second comparator  32 . A third one of the three detection modules  20  is connected to the positive terminal of the first comparator  31  and the positive terminal of the second comparator  31 . A base of the first transistor Q 1  is connected to the first comparator  31  via a sixth resistor R 6 , and an emitter of the first transistor Q 1  is connected to a power supply (not shown). The emitter of the first transistor Q 1  is also connected to a positive pin of a first one of the two fans  40 , and a collector of the first transistor Q 1  is grounded via a third capacitor C 3 . A negative pin of the first one of the two fans  40  is grounded. A base of the second transistor Q 2  is connected to the second comparator  32  via a seventh resistor R 7 , and an emitter of the second transistor Q 2  is connected to a power supply (not shown). The emitter of the second transistor Q 2  is also connected to a positive pin of a second one of the two fans  40 , and a collector of the second transistor Q 2  is grounded via a fourth capacitor C 4 . A negative pin of the second one of the two fans  40  is grounded. In one embodiment, the model of the first and second transistors Q 1 , Q 2  are SSM2135S. 
         [0016]    In use, the power supply module  10  offers a stable voltage U 0  to the three detection modules  20 . The first sliding end  14  is slid to change the resistance of the first sliding rheostat  12 . Then, the stable voltage U 0  of the three detection modules  20  is changed to a voltage U 1  via the sliding rheostat  12  and the first and third resistors R 1 , R 3 , and inputted to the negative terminal of the operational amplifier  22 . In addition, the stable voltage U 0  of the sensor  21  is changed to a voltage U 2  according to the temperature to input to the positive terminal of the operational amplifier  22 . The voltage U 1 , U 2  are changed to a voltage U 3  by the operational amplifier  22  and is displayed as a temperature value by the display  23 . The voltage U 3  of the three detection modules  20  are inputted into the control module  30 . The voltage U 3  of the first one of the three detection modules  20  is compared with the voltage U 3  of the third one of the three detection modules  20  via the first comparator  31  to generate a voltage U 4 . Then, the control module  30  controls the first one of the two fans  40  according to the voltage U 4  and a voltage range Uref. For example, if the voltage U 4  is in the voltage range Uref, the control module  30  starts the first one of the two fans  40 ; and if the voltage U 4  is out of the voltage range Uref, the control module  30  stops the first one of the two fans  40 . Similarly, the voltage U 3  of the second one of the three detection modules  20  is compared with the voltage U 3  of the third one of the three detection modules  20  via the second comparator  31  to generate a voltage U 5 . Then, the control module  30  controls the second one of the two fans  40  according to the voltage U 5  and a voltage range Uref. For example, if the voltage U 5  is in the voltage range Uref, the control module  30  starts the second one of the two fans  40 ; and if the voltage U 5  is out of the voltage range Uref, the control module  30  stops the second one of the two fans  40 . 
         [0017]    It is to be understood, however, that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only and changes may be made in detail, especially in the matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.