Abstract:
A modular UPS unit with an internal central support structure. Each module can be removed from the structure independent of the others, permitting hot swapping of the modules. The internal support structure simplifies the manufacture of the unit, minimizes the size, and the unit is easily expanded in the field. The uninterrupted power supply has a base section, a central support structure and uninterrupted power supply modules. The central support structure is modular and can be connected to the base. Additional modular sections can be added to the central support section. The modular sections are formed from panels having male fasteners and I/O connectors on the front of each panel. The uninterrupted power supply modules have female fasteners for connecting with the male fasteners on the panels and I/O connectors for connecting to the I/O connectors on the panel.

Description:
FIELD OF THE INVENTION 
     The invention relates to a chassis for a uninterruptible power supply (UPS), and more particularly to a modular UPS unit with an internal support structure which simplifies the construction of the UPS unit and allows the UPS unit to be easily expanded. 
     BACKGROUND OF THE INVENTION 
     An uninterruptible power supply, well known as a UPS, is typically used as a buffer between commercially supplied power and an electrical load, such as a computer, blood analyzer or other electronic equipment. If line voltage is interrupted, power to the load is maintained for a limited amount of time to operate the load during the interruption or to provide time to properly shut down the load without resulting damage. An on-line UPS typically comprises a converter, inverter, and battery charger. The UPS converts the commercially supplied AC power to DC power and then back to AC power. This conversion isolates the load equipment from spikes and sags in the commercially supplied power and corrects variances in line voltages. DC power is used to charge a battery. The battery can then be used to supply AC power to the load when the commercially supplied power is interrupted 
     In commercial applications, loads may change over time. As computer networks are expanded the load on the UPS increases. In order to meet this increase in demand, either a larger UPS is needed or a plurality of modular UPS units can be connected together to meet the required power level. 
     Known designs for a modular UPS have utilized one of two basic concepts. The first concept is to make each module an independent chassis. The modules can then be stacked or piled next to each other in order to make the necessary electrical connections. The problem with this concept is that it is difficult to move the unit and changing a module may require modules to be disconnected during the operation of the system. The second concept of designing a modular UPS has been to build a freestanding chassis that is essentially a large receptacle for the modules. This design solves the problems of mobility and service, but increases the size of the unit, makes the unit more difficult to manufacture, and limits field expandability. Thus, there is a need for a modular UPS unit that is easy to maintain, expandable and easy to manufacture. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing background, it is therefore an object of the invention to provide a modular UPS unit in response to, and in satisfaction of, the aforementioned needs. The invention is a modular UPS unit with an internal support structure. By utilizing a central support structure, the UPS unit is mobile and each module can be removed from the structure independent of the others, thus allowing for hot swapping of the modules. By using an internal support structure rather than an external structure, the manufacture of the unit is greatly simplified, the size is kept to a minimum, and the unit can be easily expanded in the field. 
     According to one embodiment of the invention, an uninterrupted power supply chassis is disclosed. The uninterrupted power supply comprises a base section, a central support structure and uninterrupted power supply modules. The base section has a top and bottom wherein the top of the base section has a plurality of different slots for accepting a plurality of different protrusions. The central support structure is comprised of at least a first pair of panels which are fastened together back to back, each panel has a front, back, top and bottom, wherein the plurality of protrusions are provided on the bottom of each panel and the plurality of different slots are provided on the top of each panel so that the first pair of panels can be connected to the base and subsequent pairs of panels can be connected to existing pairs of panels, the panels having male fasteners and I/O connectors on the front of each panel. The uninterrupted power supply modules have female fasteners for connecting with the male fasteners on the panels and I/O connectors for connecting to the I/O connectors on the panel. 
     According to another embodiment of the invention, an uninterrupted power supply chassis is disclosed. The uninterrupted power supply comprises a base section, a central support structure and uninterrupted power supply modules. The base section has a top and bottom wherein the top of the base section has a plurality of different slots for accepting a plurality of different protrusions. The central support structure is comprised of at least a first pair of panels which are fastened together back to back, each panel has a front, back, top and bottom, wherein the plurality of protrusions are provided on the bottom of each panel and the plurality of different slots are provided on the top of each panel so that the first pair of panels can be connected to the base and subsequent pairs of panels can be connected to existing pairs of panels, the panels having fasteners and I/O connectors on the front of each panel. The uninterrupted power supply modules have fasteners for connecting with the fasteners on the panels and I/O connectors for connecting to the I/O connectors on the panel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing summary of the invention, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the accompanying drawings, which are included by way of example, and not by way of limitation with regard to the claimed invention: 
     FIG. 1 is a block diagram of a UPS system according to one embodiment of the invention. 
     FIG. 2 is a front view of a modular piece of the internal chassis of the UPS unit according to one embodiment of the invention; 
     FIG. 3 is a bottom view of the modular piece of the internal chassis of the UPS unit illustrated in FIG. 2 according to one embodiment of the invention; 
     FIG. 4 is a back view of the modular piece of the internal chassis of the UPS unit illustrated in FIG. 2 according to one embodiment of the invention; 
     FIG. 5 is an end view of the modular piece of the internal chassis of the UPS unit illustrated in FIG. 2 according to one embodiment of the invention; 
     FIG. 6 is a perspective view of the modular pieces of the internal chassis being connected together according to one embodiment of the invention; 
     FIG. 7 is a perspective view of the internal chassis being connected to the base according to one embodiment of the invention; 
     FIG. 8 is a partial exploded view of FIG. 7 according to one embodiment of the invention; 
     FIG. 9 is a perspective view of UPS modules being connected to the internal chassis according to one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     The invention will now e described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     FIG. 1 is a block diagram of a UPS system  10  according to one embodiment of the invention. The UPS system  10  comprises a plurality of panels  20 , a base  40  and a plurality of modular UPS units  50 . The plurality of panels  20  is connected together as described below to form an internal chassis or central support structure. By utilizing a central support structure, the UPS system is mobile and each UPS modular unit  50  can be removed from the central support structure independent of the other modular UPS units, thus allowing for hot swapping of the modular UPS units. By using the central support structure, the manufacture of the UPS system is greatly simplified, the size of the system is kept to a minimum, and the UPS system can be easily expanded in the field. 
     Referring now to FIGS. 2-5, the internal structure of the UPS unit comprises a plurality of panels  20  which can be connected together back to back to form a fist section and then top to bottom to form additional sections which are attached to the first section. The panel  20  has a plurality of T-shaped protrusions  22  spaced apart along the bottom of the panel  20 . A plurality of screw tabs is also spaced apart along the bottom of the panel  20 . The top of the panel  20  has a plurality of T-shaped slots  24  and screw tab slots  28 . The T-shaped slots  24  and the screw slots  28  are aligned with the T-shaped protrusions  22  and the screw tabs  26 , respectively, so that the T-shaped slots  24  on the top of a panel  20  will receive the T-shaped protrusions  22  on the bottom of a second panel  20 , and the screw tab slots  28  on the top of the first panel will receive the screw tabs  26  on the bottom of the second panel  20 . A T-shaped protrusion  22  is inserted into the T-shaped slot  24  and slides forward locking into the narrow portion of the slot. A screw is then placed through the screw tab  26  and treaded into a receiving boss in the screw tab slot. It will be understood that the invention could also only use either the screw tabs or the T-shaped protrusions as the fastening means for stacking panels on top of each other. Furthermore, it will be understood that other shaped protrusions and fasteners could also be used to fasten panels together on top of each other. For example, male fasteners could be located on the bottom of each panel and female fasteners could be located on the top of each panel, or vice versa, in such a manner that the male and female fasteners fasten panels on top of each other. 
     Each panel  20  also includes a plurality of screw holes  30 ,  32  or some other fastening means, such as male/female connectors for fastening two panels together back to back as illustrated in FIG.  6 . The two panels  20   a  and  20   b  are attached together, for example, by at least one screw inserted from each side into screw holes  30 ,  32 . In this embodiment, two screws are inserted from each side but the invention is not limited thereto. 
     Each panel  20  also includes I/O connectors  36  to electrically connect each modular UPS unit to the UPS chassis. In addition, each panel  20  has a plurality of male fasteners  34  to which at least one modular UPS unit is attached. It will be understood that other fasteners can also be used instead of male/female connectors to physically connect each modular UPS unit to the UPS chassis. While the embodiment, illustrated in FIGS. 2-5, shows that two modular UPS units can be connected to each panel, it will be understood the each panel could be manufactured in such a manner so that any number of modular UPS units could be connected to each panel. 
     The I/O connectors  36  are surrounded by four mounting holes  35  to which metal plates (not shown) may be attached. The metal plates support output connecters for electronic modules or battery modules. 
     As described above, a plurality of panels can be connected back to back to form a chassis section  37  as illustrated in FIG.  6 . When two panels are connected back to back, the screw tabs  26  on the bottom of each panel are aligned with each other and the T-shaped protrusions  22  on each panel are aligned with each other as illustrated in FIG.  6 . Likewise, the tab screw slots  28  on the top of each panel are aligned with each other and the T-shaped slots  24  on the top of each panel are aligned with each other. 
     FIG. 6 also illustrates how a second section of panels  39  can be attached to a first section of panels  37 . Panel  20   c  is first attached to panel  20   a  by sliding the screw tabs  26  and the T-shaped protrusions  22  on the bottom of panel  20   c  into the corresponding screw tab slots  28  and the T-shaped slots  24  on the top of panel  20   a . Then panel  20   d  is attached to panel  20   b  by sliding the screw tabs  26  and the T-shaped protrusions  22  on the bottom of panel  20   d  into the corresponding screw tab slots  28  and the T-shaped slots  24  on the top of panel  20   b . Then a matching pair of screws  38  are inserted from each side to fasten together panels  20   c  and  20   d . Screws are then inserted into the screw tabs  26  to securely fasten section  37  to section  39 . It will be understood in the art that the T-shaped protrusions  22  and the screw tabs  26  could be located on the top of each panel and the T-shaped slots  24  and the screw tab slots  28  could be located on the bottom of each panel without departing from the spirit and scope of the invention. 
     The connection of the central support structure to the base  40  will now be described with reference to FIGS. 7 and 8. The base  40  can be optionally supplied with wheels  42  so as to improve the mobility of the UPS system  10 . The base is provided with an upper surface  46  onto which section  37  is to be connected. The upper surface  46  has a plurality of T-shaped slots  24  and screw tab slots  28  which correspond the T-shaped protrusions  22  and the screw tabs  26  on each of the panels  20 . Panel  20   a  is first attached to the base by sliding the screw tabs  26  and the T-shaped protrusions  22  on the bottom of panel  20   a  into the corresponding screw tab slots  28  and the T-shaped slots  24  on the upper surface  46  of the base  40 . Then panel  20   b  (not shown) is attached to base  40  by sliding the screw tabs  26  and the T-shaped protrusions  22  on the bottom of panel  20   b  into the corresponding screw tab slots  28  and the T-shaped slots  24  on the upper surface  46  of the base  40 . Then a matching pair of screws  38  are inserted from each side to fasten together panels  20   a  and  20   b . Screws  44  are then inserted into the screw tabs  26  to securely fasten section  37  to the base  40 . It will be understood in the art that the T-shaped protrusions  22  and the screw tabs  26  could be located on the upper surface of the base  40  and the T-shaped slots  24  and the screw tab slots  28  could be located on the bottom of each panel without departing from the spirit and scope of the invention. 
     FIG. 9 illustrates how each modular UPS unit  50  is attached to the central support structure. As mentioned above, each panel has a plurality of male fasteners or clips  34 . Each modular UPS unit  50  has a plurality of female fasteners or latches  52  arranged so that they align with the male fasteners on a section of each panel. The modular UPS units are attached to the central support structure by a pair of clips  34  on each panel that snap into matching latches  52  inside each modular UPS unit  50 . It will be understood that other types of fasteners could be used instead of clips and latches to fasten each modular UPS unit to the central support structure. For example, the clips could be provided on each modular UPS system and the corresponding latches can be provided in each panel. In addition, each modular UPS unit  50  has input/output connectors  54  which connect to the input/output connectors  36  on the central support structure to electrically connect the modular UPS units  50  to the UPS system  10 . 
     Although a preferred embodiment of the invention has been described in the context of a UPS system, it is to be understood that the invention can be used in other systems made up of modular components in which it may be advantageous to provide an expandable chassis with an internal support structure. Additionally, while the invention has been illustratively described in its preferred form, it is not intended to limit the scope of the claims that follow the specifics of that design form, inasmuch as variations equivalent thereto are feasible without departing from the novel inventive concepts involved. These and other variations are contemplated to fall within the scope of the claims that follow.