Abstract:
Two alternative mounting methods and devices for mounting rails achieve new points of mounting ( 8 ) by adding new pitch-holes to mounting rails ( 2 ) and using either adjustable cage-nuts or cage-nuts containing two nuts in their respective pitch-holes. The shape of the new pitch-holes preserves the structural integrity of mounting rails ( 2 ). The number of mounting points and possibilities can be dramatically increased, thereby satisfying various ventilation and pass-through requirements between devices ( 5 ).

Description:
BACKGROUND OF THE INVENTION 
     This invention comprises two alternate mounting methods and devices to secure a variety of measuring, musical, telecommunications, audio, videorecording and similar devices to mounting rails equipped with square pitch-holes in either standardised or otherwise regular attachment. Typically mounting devices comprise bolts securing the front plates of sub-racks to cage nuts installed in the square-pitch holes in the mounting rails. As a result of standardised or regular pitch-hole arrangement mounting locations are limited. Alternate mounting methods and devices described here will increase the amount of mounting locations. 
     The use of mounting rails has arisen from the need to combine together different self-contained pieces of equipment by housing them in sub-rack cases. Mounting rails have then been used to build cabinets, to which pieces of equipment have been installed by securing them from their front plates to the mounting rails. Cover-plates and parts needed for structural integrity of the cabinet have typically also been secured to the mounting rails. Early mounting rails were typified by holes equipped with grooves drilled to solid metal rails, but they gave way to solutions like the cage-nut, allowing bigger tolerances of measure, choice of grooves to be used and easier maintenance in case of breakage. 
     There are also known from the past mounting methods based on receptacles for mounting bolts that move freely along the total length of the mounting rail. System such as this allows securing of sub-racks to any height chosen in the mounting rail. However, securing receptacles that are allowed to move freely vertically are unreliable with heavy loads, as securing is based on friction or similar arrangement. Horizontal straightness of sub-racks to be mounted is not easy to achieve and their distances from each other doesn&#39;t remain constant as new sub-racks are added in the course of time. Freely adjustable mounting has usually been used only in lightweight assemblies or in panel- or sub-assemblies within sub-racks themselves. The profile structure used in freely adjustable mounting rails makes it an expensive solution. 
     Mounting rails with fixed pitch-holes arranged according to standard also pose problems. Due to standards widely used by rack-cabinet manufacturers the mounting-holes of equipment front plates correspond to the size of the equipment unit U (U=unit). Fixed in width, the size of equipment varies in height, expressed in sequence of U&#39;s as in 1U, 2U, 3U, etc. Exact directives regulating rack-rail pitch-hole and front plate mounting hole arrangement can be found in standards. Most common arrangement can be found for example in IEC standard 297. 
     Due to the combined effects of this system of mounting and standardisation the space needed for cable pass-throughs and ventilation between the sub-racked pieces of equipment always requires at least 1U of empty space to be left. Leaving an in-between space of at least lU is also required when mounting pieces of equipment that don&#39;t conform to standard heights, or devices that have standing-feet for free-standing operation. The required amount of space to be left empty in a rack-cabinet varies according to specific needs of different groups of end-users. 
     Practice has shown, that due to standardisation, in extreme cases only every second 1U space available in a mounting rail can be used. This is specifically true when four-point mounting (securing the device from all of it&#39;s front plate&#39;s four corners) is used. Securing the device only from its two lowest front plate mounting-holes allows it to be secured to mounting rail pitch-holes intended to secure front plates upper portion, but because of the nature of pitch-hole sequence this approach is only valid for one particular piece of equipment, as the next device immediately above would have to be secured only from its uppermost front plate mounting-holes. This would result in a highly unstable mounting. No significant advantage or variation can be gained by applying two-point mounting to an EIC regulated mounting rail in an effort to reduce the size of empty space between devices. Two-point mounting adds stress to mounting structures and is totally unacceptable in mobile installations. 
     To add variation to the mounting possibilities allowed by IEC standard, an additional pitch-hole of fixed type has sometime been added exactly in the middle of each space designed to receive 1U in the mounting rail. Using this additional pitch-hole it is possible to randomly create smaller gaps between units to be mounted, but all but 3U high devices and certain specially formatted devices can only be two-point mounted in this position. As such, these pitch-holes do not constitute a significant improvement to the standardised arrangement. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention described here adds flexibility to mounting procedures of rack-devices by allowing four-point mounting of any device equipped with EIC 297 defined mounting-holes using any pitch-hole, including the new additional pitch-hole described here, as a starting point for mounting. Additional mounting possibilities allow creation of smaller gaps when space for ventilation, cable pass-through or such is needed between devices. Devices can also be mounted adjacent to each other even when starting the mounting from the new mounting-point. The biggest advantage of the solutions described here is total compatibility with the most widely used present standards and devices conforming to them. The invention&#39;s implementation would be cost-effective and requires only minor changes to already existing production. Mounting rails have to be equipped with new pitch-holes, but at the same time the original mode of mounting can be maintained by using ordinary mounting-devices. Vice-versa, the new mounting devices can be used in unmodified mounting rails. The cost of production of this invention does not differ significantly from present solutions, and the tooling costs needed to start the production are fairly small. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the principle by which devices are mounted to mounting rails equipped with additional adjustment-enabling pitch-holes. 
     FIG. 2 shows one possible mode of execution of a mounting rail equipped with additional adjustment-enabling pitch-holes. 
     FIG. 3 shows the adjustment-enabling cage without the nut enclosed. 
     FIG. 4 shows the adjustment-enabling cage with an adjustable nut enclosed. 
     FIG. 5 shows a vertical cut-away view of the adjustable mounting-point. 
     FIG. 6 shows a horizontal cut-away view of the adjustable mounting-point. 
     FIG. 7 shows the principle by which devices are mounted to mounting rails equipped with additional groove-like stationary pitch-holes. 
     FIG. 8 shows one possible mode of execution of a mounting rail equipped with additional groove-like stationary pitch-holes. 
     FIG. 9 shows the cage designed to contain two nuts without the nuts enclosed. 
     FIG. 10 shows the cage designed to contain two nuts with the nuts enclosed. 
     FIG. 11 shows a vertical cut-away view of the new stationary mounting-point. 
     FIG. 12 shows a horizontal cut-away view of the new stationary mounting point. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The characterizing qualities of this invention include additional square pitch-holes with a groove or grooves running from their sides lengthwise to the mounting rail which are made between the usual pitch-holes. Mounting bolts penetrating through the new pitch-holes can be adjusted lengthwise to the mounting rail to reach new points of mounting necessitated by the fixed-point standard pitch-holes. During adjustment mounting-bolts passing through new pitch-holes move as a unit with their receiving nuts lengthwise to the mounting rail. In this mounting method at least two mounting-holes of a device&#39;s front plate will be secured to standard pitch-holes, into which it is possible to assemble either a non-adjustable or an adjustable but immobilized cage-nut. This mounting method allows the use of both adjustable and nonadjustable mounting devices together, or the use of adjustable mounting devices alone. Devices to be four-point mounted vary in size by unit size U. Adjustment-enabling cage also allows the nut inside to be locked immovable with the aid of locking devices such as ledges or screws located in the sides of the cage. Mounting wings attaching the adjustable cage-nut to it&#39;s pitch-hole are located at either end, or in the middle of the cage. At both ends of the cage reside flanges, or their equivalent, preventing the nut from falling out of the cage enclosing it. Mounting-wings and separate flanges on the top of the cage close the nut inside from the top. The cage is manufactured from a single piece of metal or a suitable alternative. 
     Alternatively the square pitch-holes of an ordinary mounting rail are equipped with additional grooves running longitudinally to the mounting rail, thus forming new, mounting-screw receiving pitch-holes. At each mounting location defined for 1U these grooves run from the lower pitch-hole&#39;s upper side and upper pitch-hole&#39;s lower side towards the center of the aforementioned 1U mounting location. The new mounting device, a cage-nut containing two nuts, is fastened by its mounting-wings to the square pitch-hole in such a manner that the nut residing beneath the mounting-wings is located under the old pitch-hole, and the second nut at the other end of the cage is situated under the additional groove forming the new pitch-hole. A groove at the bottom of the cage-nut allows pass-through of the fastening screws. The mounting-wings attaching the cage-nut to it&#39;s pitch-hole are located at the extreme end of the cage containing the two nuts. At both ends of the cage reside flanges, or their equivalent, preventing the nut from falling out of the cage enclosing it. Mounting-wings and separate flanges on the top of the cage close the nuts inside from the top. The cage is manufactured from a single piece of metal or a suitable alternative. 
     Considerable benefits are gained by the use of either mounting method and device as described here. Space-efficiency of mounting can be increased as it is no longer necessary to leave a minimum of 1U empty space, if empty space between devices is called for. The mounting methods and devices described here are economic and simple solutions to practical problems inherent in partly aged standard environment. The invention described here works flawlessly in the present standardised environment, such as that represented by IEC 297. Rack-installations demanding cable pass-throughs and ventilation can now be executed more efficiently and increased possibilities of four-point mounting increase structural strength and reduce the possibility of damage. 
     Referring to the drawings, FIG. 1 shows one possible use of a mounting rail as a part of a cabinet structure. Cabinet space frame  1  comprises mounting rails  2  acting as cornerposts. In this case, they are defined as L-profile rails. Supportive struts  3  have been fixed to mounting rails  2 . Plates can be used as walls and ceiling to shield the cabinet. Devices  5  are mounted with their casings  6  towards the inside of cabinet  1 . The front plates  7  of the devices  5  are secured to mounting rails  2  through holes  9 . Unitsize U shows the height of device  5 . Arrow  10  indicates the empty space between devices  5 . 
     In FIG. 2 the mounting rail  2  is shown in enlarged form. The flanges of L-profile are marked by numbers  11  and  12 . The old square pitch-holes  13  conforming to standard are located lengthwise to the mounting rail  2  in such a manner, that distance a is equivalent to the distance of holes in a 1U front plate  7  and distance b is equal to the shortest distance between mounting points  8 . The new pitch-hole  14  is located in the middle of distance a. Grooves  15  are located to the sides of pitch-hole  14  lengthwise to mounting rail  2 , thereby enabling sufficient adjustability without compromising the structural strength of mounting rail  2  and ledge  16 . 
     In FIGS. 3-6 the respective structures of an adjustment-enabling mounting device and a mounting-point are shown. The adjustable cage  17  to be used in new pitch-holes  14  is made by folding it from single piece of metal or by other means convenient. The bottom  18  contains a groove  19 , through which screw  20  of any length can move while being adjusted to a suitable position. The nut  21  is enclosed between sidewalls  22  and  23 . On both ends of adjustment-enabling cage  17  lie flanges  24 , which prevent nut  21  from falling out from the cage  17 . Flanges  25  located on the top of sidewalls  22  and  23  and mounting-wings  26  close the nut  21  from above within cage  17 . On the other end of cage  17  lie mounting-wings  26  with it&#39;s sides  27  and  28  forming a groove  29  wide enough to attach to flange  11  of mounting rail  2 . Cage  17  is installed to pitch-hole  13  or  14  by pressing the cage in such a manner, that flange  11  is pressed into grooves  29 . While tightening bolt  20  nut  21  presses the lower part  28  of mounting-wing  26  and flanges  25  against flange  11 . The upper parts  27  of mounting-wings  26  are pressed between flange  11  and the front plate  7  of device  5 . Because the pitch-holes  13  and  14  in mounting rail  2  lie fairly close to each other it is convenient to locate mounting-wings  26  at the far end of cage  1 . Thus, when pitch-holes  13  and  14  are close to each other, space can be saved by changing the mounting direction of cage  17 . The nut  21  can be locked immoveable with ledges  30  located in sidewalls  22  and  23 . 
     FIG. 7 shows again one possible use of a mounting rail as a part of cabinet structure. Cabinet space-frame  1  comprises mounting rails  2  acting as cornerposts. In this case, they are defined as L-profile rails. Supportive struts  3  have been fixed to mounting rails  2 . Plates can be used as walls and ceiling to shield the cabinet. Devices  5  are mounted with their casings  6  towards the inside of cabinet  1 . The front plates  7  of the devices  5  are secured to mounting-points  8  in mounting rails  2  through holes  9 . Unitsize U shows height of device  5 . Arrow  10  indicates the empty space between devices  5 . 
     FIG. 8 shows the mounting rail  2  in enlarged form. The flanges of L-profile are marked by numbers  11  and  12 . The old square pitch-holes  13  conforming to standard are located lengthwise to the mounting rail  2  in such a manner, that distance a is equivalent to the vertical distance of holes in a 1U front plate  7  and distance b is equal to the shortest distance between mounting-points  8 . Distance d is also equivalent to the vertical distance of holes in a 1U front plate  7  and it also shows the new positioning of devices  5  made possible by new pitch-holes  31 . The new pitch-holes  31  run groove-like from old pitch-holes  13  towards the center of space reserved for 1U. Groove-like in shape, they allow for new mounting-points  31  without weakening mounting rail  2  and ledge  32 . 
     FIGS. 9-12 show the respective structures of the new nonadjustable pitch-hole and mounting device. Cage-nut  33  functions as a securing-device in the combination of pitch-holes  13  and  31  and it&#39;s made by folding it&#39;s cage from a single sheet of metal or other suitable material. At the bottom of the cage  33  lies a groove  35  allowing screws  36  of any length to pass through the cage  33 . Nuts  37  are contained between sidewalls  38  and  39 . At both ends of cage  33  lie flanges  40  to prevent nuts  37  from escaping. Flanges  41  and  42  situated on top of sidewalls  39  and  39  and mounting-wings  42  enclose nuts  37  within cage  33  from above. Mounting-wings  42  are situated on the other end of cage  33  forming a groove wide enough to receive flange  11  of the mounting rail  2 . To mount cage-nut  33  to it&#39;s pitch-hole  13  the cage  33  is pressed in such a manner that flange  11  is pressed to grooves  45 . As screw  36  located in pitch-hole  13  is tightened the nut  37  presses lower portions  44  of mounting-wings  42  and flanges  41  against flange  11 . The upper portions  43  of mounting-wings  42  are pressed between flange  11  and the front plate  7  of device  5 . When tightening screw  36  located in pitch-hole  31  the nut  37  presses the flanges  41  against flange  11  while front plate  7  of device  5  is pressed against the other side of flange  11 . 
     The adjustment-enabling mounting method and device described in FIGS. 1-6 works in a following manner. Additional pitch-holes  14  are added to IEC 297 regulated mounting rails  2 . Adjustment-enabling cage-nuts  17  are then installed in these pitch-holes  14 . To fully cover the range of adjustment allowed by pitch-hole  14 , cage-nut  17  should be turned into direction of either groove  15 . In practice it is easiest to secure front plates  7  to standard pitch-holes  13  as they comprise a fixed mounting-point  8  when using old-fashioned cage-nuts. If adjustment-enabling cage-nuts are to be used in standard pitch-holes  13  it would be advisable to immobilize nut  17  using ledges  30  to ease assembling. It would be practical to start securing of front plates  7  of devices  5  from adjustable mounting-points  8  and adjust the device to reach fixed mounting-points  8 . 
     The alternate non-adjustable mounting method and device described in FIGS. 7-12 works in a following manner. New, groove-like pitch-holes  31  are added to standard mounting rails  2 . Cage-nuts  33  containing two nuts  37  are mounted to pitch-holes comprising a combination of pitch-hole  13  and pitch-hole  31  in such a manner that nut  37  under mounting-wings  42  is positioned to correspond with pitch-hole  13  and the other nut  37  corresponds with pitch-hole  31 . Mounting of devices  5  can now take place either to original pitch-holes  13  or with a half a U deviation to pitch-holes  31 . 
     It is obvious to a professional that different modes of execution can be applied to both alternate methods and devices. In the solution described in FIGS. 1-6 the square nut  21  could be substituted with a standard hexagonal nut or similar equivalent. The mounting-wings  26  of cage  17  can reside anywhere on its longitudinal axis, provided that this is reflected in the form of the new pitch-hole  14 . Locking devices  30  can take any form deemed efficient, including solutions based on friction, etc. In the alternate solution described by FIGS. 7-12 the new pitch-hole  31  could be executed as a plain round hole. The combined shape of pitch-holes  13  and  31  could also be totally re-designed if compatibility with the standard system is not needed.