Abstract:
A mounting device includes a housing for accommodating electronic units, a fan for sending cooling air to the electronic units and air flow control devices for controlling flow of the cooling air. Each air flow control device includes a first panel having at least one opening for the cooling air to pass therethrough, a second panel, slidably provided to overlap the first panel, for opening or closing the opening of the first panel, a driving force generation mechanism provided in the airflow path for cooling air and having an air receiving member for receiving an air pressure of the cooling air, the driving force generation mechanism for generating a driving force corresponding to the air pressure received by the air receiving member and a link mechanism, for receiving the driving force generated by the driving force generation mechanism and for providing a driving force that slides the second panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No.2010-214433, filed on Sep. 24, 2010, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to a mounting device for electronic unit and an air flow control device. 
     BACKGROUND 
     A mounting device for electronic unit is known that includes a plurality of stages of shelves in each of which a plurality of electronic units, such as printed wiring boards on which a hard disk drive (HDD), a power supply, and an electronic part are mounted, are accommodated in parallel. A duct is provided in a device housing and a cooling fan is provided in the duct. Heat from the electronic units is led to the duct through airflow paths between the electronic units, and then discharged to the outside of the device housing. Japanese Laid-open Patent Publication Nos. 2007-73720 and 11-204974 are examples of related art 
     Therefore, when the common cooling fan within the device housing is used to uniformly cool each electronic unit, it is desired that a cooling air for each electronic unit does not has a low pressure loss and is uniformed. 
     However, the plurality of electronic units included in the mounting device for electronic unit are different in height, are different in shape depending on mounted parts, and thus do not necessarily have the same shape. Therefore, when the shape of each electronic unit is different, the pressure loss of the cooling air for each electronic unit is different. In addition, the pressure loss of the cooling air for each electronic unit is different also depending on a manner of arranging the electronic units to the shelf of the mounting device for electronic unit. Therefore, it is desired to control a flow of the cooling air to be constant for each electronic unit. 
     SUMMARY 
     According to an aspect of the invention, a mounting device includes a housing in which accommodation portions accommodating a plurality of electronic units, respectively, are arranged in parallel, a fan configured to send cooling air to the plurality of electronic units and a plurality of air flow control devices, provided in an airflow path for the cooling air in accommodation portions, configured to control flow of the cooling air. Each air flow control device includes a first panel having at least one opening for the cooling air to pass therethrough, a second panel, slidably provided to overlap the first panel, configured to open or close the opening of the first panel, a driving force generation mechanism provided in the airflow path configured to cool air and have an air receiving member for receiving an air pressure of the cooling air, the driving force generation mechanism configured to generate a driving force corresponding to the air pressure received by the air receiving member and a link mechanism, coupled to the driving force generation mechanism and the second panel, configured to receive the driving force generated by the driving force generation mechanism and provide a driving force that slides the second panel. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a structure of a mounting device for electronic unit. 
         FIG. 2  is a front view illustrating the structure of the mounting device for electronic unit. 
         FIG. 3  is a diagram for illustrating an air flow control method according to a comparative example. 
         FIG. 4  is a diagram for illustrating an air flow control method according to an embodiment. 
         FIG. 5  is an exploded perspective view illustrating a structure of an air flow control device. 
         FIGS. 6A and 6B  are plan views illustrating the structure of the air flow control device. 
         FIGS. 7A and 7B  are diagrams illustrating an operation of the air flow control device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of the present techniques will be explained with reference to accompanying drawings. 
     Hereinafter, an embodiment will be described in detail with reference to the drawings.  FIG. 1  is a perspective view illustrating a structure of a mounting device for electronic unit.  FIG. 2  is a front view illustrating the structure of the mounting device for electronic unit. The mounting device for electronic unit  1  according to the embodiment includes a housing  10  having a rectangular parallelepiped shape. 
     The housing  10  is provided with an accommodation space in an inside thereof, and is provided with a door (not shown) that closes the accommodation space. In the accommodation space, five stages of shelves  11  to  15  are provided. Each of the shelves  11  to  14  is provided with walls that divide the accommodation space into a plurality of portions, and a plurality of accommodation portions  11   a  to  11   j ,  12   a  to  12   j ,  13   a  to  13   j , and  14   a  to  14   j  are provided. 
     An air flow control device  21  is mounted in each of the accommodation portions  11   a  to  11   j  of the shelf  11 . An electronic unit  22  is mounted in each of the accommodation portions  12   a  to  12   j  of the shelf  12  above the shelf  11 . Similarly, an air flow control device  21  is mounted in each of the accommodation portions  13   a  to  13   j  of the shelf  13 . An electronic unit  22  is mounted in each of the accommodation portions  14   a  to  14   j  of the shelf  14  above the shelf  13 . 
     A plurality of cooling fans  16  are mounted in the topmost shelf  15 . The plurality of cooling fans  16  sends cooling air for cooling the electronic units  22 . In the embodiment, the cooling fans  16  are driven so as to send the cooling air from bottom toward top. 
       FIG. 3  is a diagram for illustrating an air flow control method according to a comparative example. Walls that divide an accommodation space into a plurality of portions are provided in the shelf, and accommodation portions  114   a  to  114   e  are formed. In the accommodation portions  114   a  to  114   e , corresponding electronic units  122   a  to  122   e  are mounted. Cooling fans  116   a  and  116   b  are mounted above the accommodation portions  114   a  to  114   e  and are driven so as to suck cooling air from each accommodation portion and send cooling air from bottom toward top. 
     The electronic units  122   a  to  122   e  are of a plurality of types, and the pressure loss is different depending on the types. The higher the pressure loss is, the lower the flow of the cooling air is. The lower the pressure loss is, the higher the flow of the cooling air is. Therefore, due to the difference in pressure loss, the flow of the cooling air for each electronic unit does not become constant. 
     Therefore, in order to cause the flow of the cooling air flowing in each accommodation portion to be constant, an air flow adjusting plate  131  is provided on the suction side or discharge side of the accommodation portions  114   a  to  114   e . In  FIG. 3 , the air flow adjusting plate  131  is provided at suction ports  130 . 
     The air flow adjusting plate  131  is a metal plate provided with a plurality of openings. Here, each of suction ports at the accommodation portions  114   a  to  114   e  is designed so as to correspond to the difference in pressure loss of the cooling air between the electronic units  122   a  to  122   e . In other words, the air flow adjusting plate  131  is designed such that the opening rate is high at a portion where the pressure loss is low and is low at a portion where the pressure loss is high. 
     Specifically, the shapes of the openings, the sizes of the openings, and the number of the openings of the air flow adjusting plate  131  are adjusted. By so doing, the flow of the cooling air sucked from the suction side of the accommodation portions  114   a  to  114   e  may be constant. It should be noted that when a plurality of stages of shelves are provided, an air flow adjusting plate  131  is similarly designed and arranged to each shelf. 
     However, the air flow adjusting plate  131  is designed according to electronic units mounted in the shelf. Thus, later, the arrangement of the electronic units may not be changed, and the electronic units may not be replaced with other ones. In addition, when an electronic unit is desired to be replaced, the air flow adjusting plate  131  needs to be designed all over again. Therefore, it is desired that air flow control is more easily and efficiently performed when electronic units having different pressure losses are additionally mounted in the mounting device for electronic unit. 
     Further, it is also considered that the air flow is monitored with an air flow sensor and the opening rate of the air flow adjusting plate  131  is changed by operating an electric shutter in accordance with the air flow. However, the electric control needs electric power and causes a heat source, and thus is not necessarily an efficient cooling method. Therefore, the air flow control is performed by a mechanical method without needing electric power. 
       FIG. 4  is a diagram for illustrating an air flow control method according to the embodiment.  FIG. 4  illustrates a part of the shelves  13  and  14  of the mounting device for electronic unit. Walls that divide the accommodation space into a plurality of portions are provided in the shelf, and the accommodation portions  14   a  to  14   e  are formed. In the accommodation portions  14   a  to  14   e , corresponding electronic units  22   a  to  22   e  are mounted. Cooling fans  16   a  and  16   b  are mounted above the accommodation portions  14   a  to  14   e  and are driven so as to suck cooling air from each accommodation portion and send the cooling air from bottom to top. 
     The electronic units  22   a  to  22   e  are of different types, respectively, and have different pressure losses. Thus, in order to cause the flow of the cooling air flowing in each accommodation portion to be constant, a plurality of air flow control devices  21   a  to  21   e  are provided on the suction side or the discharge side of the accommodation portions  14   a  to  14   e.    
     In  FIG. 4 , the air flow control devices  21   a  to  21   e  are provided to suction ports  30 . It should be noted that when mounted on the discharge side, the air flow control devices are provided to a discharge port  50 . Specifically, the air flow control devices  21   a  to  21   e  are located in the accommodation portions  13   a  to  13   e  that are airflow paths for cooling air flowing into the accommodation portions  14   a  to  14   e . First and second panels  33  and  34  are located so as to overlap each other at positions where the accommodation portions  14   a  to  14   e  face the suction ports  30 . 
     Driving force generation mechanisms  25  are located at the suction ports for the cooling air flowing into the accommodation portions  13   a  to  13   e , and are rotated by air pressure. By using the rotation force, the second panel  34  slides relative to the first panel  33 . The detailed configuration and operation will be described with reference to  FIGS. 5 to 7B . 
       FIG. 5  is an exploded perspective view illustrating a structure of the air flow control device.  FIGS. 6A and 6B  are plan views illustrating the structure of the air flow control device.  FIGS. 6A and 6B  illustrates a part of the accommodation portions  13   a  and  14   a  of the mounting device for electronic unit. The air flow control device  21  is located in the accommodation portion  13   a  that communicates with the suction port  30  of the accommodation portion  14   a . The air flow control device  21  includes the first and second panels  33  and  34  and the driving force generation mechanism  25 . 
     The first and second panels  33  and  34  are fitted to a peripheral wall surface of the suction port  30  of the accommodation portion  14   a  so as to overlap each other. The width of the second panel  34  is smaller than the width of the accommodation portion  14   a . Upper and lower wall surfaces  31  are provided with rails  31   r , respectively. The upper and lower portions of the first and second panels  33  and  34  are fitted into the rails  31   r.    
     In upper, lower, left, and right grooves  34   m  of the second panel  34 , cylindrical slide rollers  34   r  each of which is one example of a slide member are provided, respectively. Therefore, the slide rollers  34   r  roll and move along the rails  31   r . As described above, the first panel  33  is fixed to the wall surfaces  31 , but the second panel  34  is provided to the wall surfaces  31  so as to be slideable along the rails  31   r.    
     Main surfaces  33   h  and  34   h  of the first and second panels  33  and  34  are provided with a plurality of rectangular slits  33   s  and  34   s  each of which is one example of an opening. These slits  33   s  and  34   s  have the same size and are arranged at regular intervals. It should be noted that the sizes, the shapes, and the arrangements of the slits may be determined in accordance with a needed opening rate. Therefore, the slits  33   s  and  34   s  may have different sizes, shapes, and arrangements. 
     When the second panel  34  moves in a closing direction (Sr direction), the slits  33   s  and  34   s  gradually shift from each other, and the main surface  33   h  of the first panel  33  overlaps the slits  34   s . Similarly, the main surface  34   h  of the second panel  34  overlaps the slits  33   s . Therefore, when the slits  33   s  and  34   s  completely coincide with each other, the opening rate of the slits  33   s  is 100%, and the opening rate of the slits  33   s  gradually decreases as the second panel  34  moves in the closing direction (Sr direction). 
     When the slits  33   s  and  34   s  completely shift from each other, the main surface  34   h  completely overlaps the slits  33   s  and the opening rate of the slits  33   s  becomes 0%. It should be noted that when the opening rate of the slits  33   s  is 0%, air does not flow into the accommodation portion of the electronic unit at all, and thus a minimum opening rate (e.g., 5%) is previously set so as to allow even a small amount of cooling air to flow in. 
     The driving force generation mechanism  25  generates a driving force for sliding the second panel  34  along the rails  31   r . The driving force generation mechanism  25  includes a rotor (propeller)  35 , an elastic member  38 , and a link mechanism  26 . The rotor  35  is a cylindrical windmill having, on its surface, a plurality of plate-like blades  35   t  each of which is one example of an air receiving member that receives cooling air. 
     A suction port  13   w  of the accommodation portion  13   a  is formed with a size that is the same as or smaller than the vertical and horizontal widths of the rotor  35 , such that the blades  35   t  receive cooling air flowing into the accommodation portion  13   a . Therefore, the flow of the cooling air flowing into the accommodation portion  13   a  is taken as accurate as possible, whereby flow control is performed. 
     The link mechanism  26  includes first and second rods  36  and  37 . The first rod  36  has, at one end thereof, an internal thread (nut)  36   h  that is coupled to an external thread (bolt)  39   h  formed at one end of a shaft  39  of the rotor  35 . 
     The second rod  37  is coupled at one end thereof to the first rod  36 . A shaft portion  36   p  of the first rod  36  is rotatably provided in an engagement groove  371  at one end of the second rod  37 . In addition, the second rod  37  is coupled at the other end thereof to the second panel  34 . A shaft portion  37   p  of the second rod  37  is rotatably provided in an engagement groove  341  of the second panel  34 . 
       FIGS. 7A and 7B  are diagrams illustrating an operation of the air flow control device. It should be noted that  FIG. 6A  described above illustrates a state where the opening rate of the slits  33   s  is 100%,  FIG. 7A  illustrates a state where the slits  33   s  are slightly closed, and  FIG. 7B  illustrates a state where the opening rate of the slits  33   s  is the minimum. 
       FIG. 6A  illustrates an initial state during stop of the cooling fan or a state where during operation of the cooling fan, the opening rate is controlled to be 100% by the air flow control device  21 . In the embodiment, the opening rate in the initial state during stop of the cooling fan is previously set to 100%. Specifically, a plate rubber that is one example of the elastic member  38  is fixed at one end thereof to the shaft  39  and at the other end thereof to a wall surface  13   h  of the accommodation portion  13   a.    
     Therefore, when a plurality of the blades  35   t  do not receive an air pressure equal to or higher than a predetermined value, the rotor  35  does not rotate due to the elastic force of the elastic member  38 . Thus, the first rod  36  and the second rod  37  wait at initial positions. Therefore, the second panel  34  waits at an initial position, and the opening rate of the slits  33   s  is kept at 100%. 
     When a plurality of the blades  35   t  receive an air pressure equal to or higher than the predetermined value, the plate surfaces are pressed by the air pressure to generate a rotary force (A direction) that rotates the rotor  35 . When the air pressure at that time is greater than the elastic force of the elastic member  38 , the rotor  35  starts to rotate. Then, the rotary force is transmitted to the link mechanism  26  and converted into a driving force that moves the second panel  34  in the closing direction (Sr direction). 
     As shown in  FIG. 7A , the internal thread  36   h  of the first rod  36  moves in a D direction along the external thread  39   h  with the rotation of the rotor  35  in the A direction. In other words, the external thread  39   h  has a thread groove that moves the internal thread  36   h  in the D direction when the rotor  35  rotates in the A direction. 
     The one end of the second rod  37  receives a rotary force (B direction) from the shaft portion  36   p  and rotates. In addition, the other end of the second rod  37  receives a rotary force (C direction) from the shaft portion  37   p  and presses the second panel  34  in the closing direction (Sr direction). Therefore, when the blades  35   t  receive an air pressure equal to or higher than the predetermined value, the second panel  34  is moved in the closing direction (Sr direction) such that the opening rate decreases. 
     When the blades  35   t  receives an air pressure of a maximum value that is previously set, the second panel  34  moves to a final position where the opening rate becomes the minimum. As shown in  FIG. 7B , the internal thread  36   h  of the first rod  36  moves in the D direction along the external thread  39   h  to a final position with the rotation of the rotor  35 . 
     The one end of the second rod  37  receives the rotary force (B direction) from the shaft portion  36   p  and rotates. In addition, the other end of the second rod  37  receives the rotary force (C direction) from the shaft portion  37   p  and presses the second panel  34  to a final position. Therefore, when the blades  35   t  receive the maximum air pressure, the second panel  34  is moved to the final position such that the opening rate becomes the minimum. 
     Then, when the air flow changes, the air flow and the elastic force of the elastic member  38  are balanced such that the second panel  34  is kept at the final position. When the air flow decreases and the air pressure falls, a driving force that inversely rotates the rotor  35  in an F direction opposite to the A direction is generated by the resilience force of the elastic member  38  in an E direction. The internal thread  36   h  of the first rod  36  moves along the external thread  39   h  in the direction opposite to the D direction with the inverse rotation of the rotor  35 . 
     The one end of the second rod  37  receives a rotary force (the direction opposite to the B direction) from the shaft portion  36   p  and rotates. In addition, the other end of the second rod  37  receives a rotary force (the direction opposite to the C direction) from the shaft portion  37   p  and presses the second panel  34  in an opening direction (SI direction). Thus, the second panel  34  starts to move in the opening direction (SI direction), and when the air pressure decreases to the predetermined value or less, the second panel  34  returns to the initial position where the opening rate of the slits  33   s  becomes 100%. 
     Further, when the air flow and the elastic force of the elastic member  38  are balanced at an intermediate position between the initial position and the final position, the second panel  34  stops moving and is kept at that position until the air flow changes. Then, when the air flow decreases and the air pressure falls, the second panel  34  starts moving in the opening direction (SI direction) by the same operation as described above. In addition, when the air flow and the elastic force of the elastic member  38  are balanced, the second panel  34  stops moving and is kept at that position until the air flow changes. 
     Further, when the air pressure decreases to the predetermined value or less, the second panel  34  returns to the initial position where the opening rate of the slits  33   s  becomes 100%. On the other hand, when the air flow increases and the air pressure rises, the second panel  34  starts moving in the closing direction (Sr direction) by the same operation as described above. In this manner, the position of the second panel  34  is controlled in response to change of the air pressure received by the blades  35   t.    
     As described above, the elastic member  38  is used for controlling movement of the second panel  34  in accordance with the air pressure received by the blades  35   t . The elastic member  38  applies the elastic force such that the rotor  35  does not rotate in the A direction unless the blades  35   t  receive an air pressure equal to or higher than the predetermined value. In addition, the elastic member  38  applies the elastic force such that the rotor  35  inversely rotates in the F direction to return to the initial position when the air pressure changes to the predetermined value or less. 
     As one example of the elastic member  38 , use of a rubber or a spring is considered.  FIGS. 6A ,  6 B,  7 A, and  7 B illustrate one example where the plate rubber is used as the elastic member  38 . The plate rubber, which is the elastic member  38 , is fixed at one end thereof to the wall surface  13   h  of the accommodation portion  13   a  and at the other end thereof to the shaft  39  of the rotor  35 . Therefore, when the shaft  39  rotates in the A direction, the plate rubber winds about the shaft  39  to generate a resilience force in the direction opposite to the rotation direction. When the rotary force in the A direction disappears and the air pressure becomes less than the predetermined value, the rotor  35  inversely rotates in the F direction to return to the initial position. 
     In this manner, the driving force generation mechanism  25  generates a driving force that moves the second panel  34  in the sliding direction, by using the air pressure of the cooling air and the elastic force of the elastic member  38 . 
     Here, a method of setting the elastic force (urging force) of the elastic member  38  will be described. The spring constant of the elastic member  38  is set by a moving amount of the second panel  34 . The opening rate of the suction port at the accommodation portion of a cooled object having an assumed maximum pressure loss is set to 100%. In addition, the opening rate of the suction port at the accommodation portion for a cooled object having an assumed minimum pressure loss is set to 5%. It should be noted that air does not flow at all if the opening rate is 0%, and thus such an opening ratio of 10% or less (not including 0) may be set that a very small amount of air flows. 
     An air pressure provided when a cooled object having the assumed minimum pressure loss is mounted is assumed, and the drawing amount of the elastic member  38  at that time is set such that the opening rate becomes 5%. The air pressure is determined by the capability and the number of the cooling fans and the sizes of cooled objects. The air pressure depends on conditions, and thus the air pressure is previously examined and determined. 
     Where an assumed air pressure and a drawing amount of the elastic member that are provided when the opening rate is 5% are indicated by Fmax and Tmax, an elastic member of which the spring constant is Fmax/Tmax is selected. The shape and material of the elastic member are arbitrarily selectable as long as it has the desired spring constant. 
     According to the configuration described above, the rotor (propeller)  35  rotates by the air pressure of the cooling fan mounted in the mounting device for electronic unit. Therefore, the lower the pressure loss is, the higher the air pressure is, and the higher the air pressure is, the more the rotor  35  rotates and the lower the opening rate of the slits  34   s  of the first panel  34  is. The lower the opening rate is, the lower the air pressure is and the less the rotor  35  rotates. 
     As a result, the air flow control device provided per electronic unit similarly moves, whereby the air pressure of the cooling air for each electronic unit is balanced. Therefore, the pressure loss of the cooling air for each electronic unit is uniformed, and the air flow becomes constant. 
     The disclosed mounting device for electronic unit and air flow control devices allow the flow of the cooling air cooling the electronic units to be easily controlled, by changing the opening rate at the airflow paths for the cooling air in the electronic units by using the air pressure of the cooling air, regardless of the shapes and the arranging method of the electronic units. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.