Patent Application
20050276017
This invention relates to housings and air flow distribution systems for telecommunication equipment assemblies and, in particular, a housing and method in which a plenum region within the housing or chassis of a telecommunications equipment assembly is employed in an air flow distribution system.
Most modern telecommunications equipment contain electronic components, devices or equipment mounted in a housing or chassis. The chassis is generally enclosed, with an access door, side walls, and a backplane. The chassis is enclosed to prevent stray material from entering the casing and damaging the electronic apparatus, and to prevent stray emission of electromagnetic energy. There can also be a midplane in the chassis. Although the term midplane suggests a location halfway between the backplane and the front of the chassis, this is not necessarily so.
In recent years, there has been a dramatic increase in functional density of telecommunications modules in regards to the reduction in space required for an amount of data process capability. At the same time, the power required to operate each module and the consequent heat generated has correspondingly increased in nearly as dramatic a fashion to the point where traditional vertically oriented or end-on-end oriented electronics modules within telecommunications systems have been or will soon be unable to realize the advantages of the functional densities now achievable as a result of heat limits.
There are a number of factors related to the ability to cool heated components in a chassis. One criterion for the rate of heat removal is the velocity of cooling air through air flow passages in the chassis. High velocity air is not enough though. A heat removal system will be ineffective if cooling air does not reach a substantial portion of heated components in the chassis.
U.S. Pat. No. 4,860,163 teaches a device for improving air flow over circuit modules. The patent describes a cabinet for holding circuit modules, with a fan, centrally located, drawing air from one end of the cabinet. There is a wall at one end of the modules closest to the fan preventing air from flowing directly from the modules to the fan. Instead, air must flow around the wall to reach the fan. To further improve air flow distribution, baffles are placed along a portion of the sides of the cabinet to force air to flow over at least a portion of the modules. For this device to help improve the evenness of air flow, it appears necessary that the fan be relatively centrally located. If, as in many electronics systems, the fan is not centrally located, air flow will not be significantly improved, if at all, in portions of the modules remote from the fan. It also appears that the device was not designed to be used in telecommunications devices having midplanes.
More recent U.S. Pat. No. 6,104,003 issued Aug. 15, 2000 describes a cabinet for housing telecommunications equipment that includes an enclosure with a subrack mounted therein. A duct delivers ambient air from outside through the bottom of the cabinet to the subrack. A subrack exit plenum is disposed above the electronic subrack for exhausting air heated by the electronics equipment. Fans are mounted above this plenum for drawing ambient air up from the inlet, through the subrack region, and through the plenum. However, this cabinet also does not appear to have a midplane extending vertically in the cabinet and to have electronic apparatuses mounted on both sides of the midplane.
Another recent patent which teaches a cabinet for electronic equipment is U.S. Pat. No. 6,538,881 which issued Mar. 25, 2003. In this cabinet, cooling air enters the cabinet through an inlet near the top of one side and then flows down through a first region of the cabinet to two fans located in the bottom of the cabinet. A portion of the cooling air can then exit through an output port in the bottom of the cabinet while another portion of the air flows upwardly through a second region of the cabinet that is separated from the first region by a vertical plate or midplane. Because of the return of cooling air into the first region from the second region, there is an accumulation of incoming and returned air passed along the first region in the cabinet.
It is an object to the present invention to provide an improved housing assembly for electronics equipment that has provision for air flow distribution.
It is a further object or another aspect of the invention to provide an improved method for providing air flow through a telecommunications equipment assembly.
According to one aspect of the invention, there is provided a housing assembly for electronics equipment comprising an external housing including a front, a back, a vertical first side panel, a vertical second side panel opposite the first side panel, a bottom end section, and a top end section. The housing also has at least one output port formed in the top end section and at least one inlet port formed in the bottom end section. There is also provided at least one fan holder for at least one air circulating fan in one of the top end section and the bottom end section. An interior vertical wall is mounted in the external housing and extends between the first side panel and the second side panel. This interior vertical wall is located between the front and back of the external housing and separates first and second regions of the housing assembly for receiving electronic apparatuses. A plenum region has a first plenum side located adjacent the at least one fan holder and an opposite second plenum side located adjacent both of the first and second regions. The plenum region extends horizontally across one edge of the interior vertical wall. During use of this housing assembly, the at least one fan is mounted in the at least one fan holder and operates to create an air pressure differential in the plenum region and this air pressure differential produces an upwards air flow through both the first and second regions of the housing assembly in order to cool the electronic apparatuses.
In one embodiment, there are two of the fan holders and these are within the top end section of the external housing with the plenum region being located below the two fan holders.
According to another aspect of the invention, a method provides air flow through a telecommunications equipment assembly which comprises a housing having exterior walls defining an internal cavity and a midplane dividing this internal cavity into a switch side and a port side. A plenum region is formed in the housing so as to extend across one edge of the midplane and along a side of the internal cavity on both the switch side and the port side. Both the switch side and the port side contain a plurality of electronic apparatuses which form a plurality of vertically extending switch side flow channels and a plurality of vertically extending port side flow channels extending to the plenum region. The assembly also includes a fan section containing one or more fans in flow communication with and adjacent to the plenum region. The method of the invention comprises creating an air pressure differential in the plenum region by operating the one or more fans and thereby producing the air flow through both the port side flow channels and the switch side flow channels, this air flow being substantially in one vertical direction. The air flow through the port side flow channels and the switch side flow channels acts to cool the electronic apparatuses during use of the telecommunications equipment assembly.
In one form of this method, the air flow through both the port side flow channels and the switch side flow channels is upwardly and the plenum region extends across a top edge of the midplane.
According to another aspect of the invention, a telecommunications equipment assembly comprises an external housing having a front end, a back end, a vertical first side panel, a vertical second side panel opposite the first side panel, a bottom end section and a top end section. At least one output port is formed in the top end section and two inlet ports are formed in the bottom section and located on opposite sides of the bottom section. A fan holding device is mounted in the top end section and two or more fans are mounted on this fan holding device. An interior vertical wall is mounted in the external housing so as to extend substantially perpendicular to the first and second side panels. This vertical wall is positioned between and is spaced from the front and the back of the housing and has a upward edge spaced below the fan holding device. This vertical wall divides the housing into front and back cavity regions. A first set of electronic apparatuses is mounted in the front cavity region and forms vertically extending first air flow passages between adjacent pairs of the electronic apparatuses. A second set of different electronic apparatuses is mounted in the second cavity region and forms second, vertically extending air flow passages. A plenum region is formed in the housing between the front and back cavity regions and the fan holding device. The plenum region extends horizontally across an upper edge of the interior vertical wall. During use of this assembly, the two or more fans operate to create a pressure differential in the plenum region that produces upwards air flow through both the first and second air flow passages and into the plenum region.
In one embodiment of this assembly, the fan holding device extends horizontally in a front to back direction relative to the housing.
The present invention will be further understood from the following detailed description with reference to the accompanying drawings.
An example of a prior art fan cooling system is illustrated in
While the above described fan cooling system may be satisfactory in uniformly cooling electronic apparatuses in the chassis 10 when the fans 26 and 34 are working properly, cooling will be non-uniform in the event of fan failure. For example, if the fan 26 fails, only the fan 34 will remain in operation. The average velocity of air flowing in the region to the left of the divider mechanism 22 will be less than the average velocity of air flowing in the region to the right of the divider mechanism 22. Consequently electronic apparatuses located in the region 46 may be inadequately cooled.
Another problem is the direction in which air moves. Air flowing in the region to the left of the divider mechanism 22 flows downwardly as opposed to upwardly. As electronic apparatuses in the chassis 10 begin to heat up there will be an upward air convection which will work against the downward flow.
Referring to
The backplane 71 includes a printed circuit board that extends substantially the width W. The circuitry of the backplane 71 is well-known in the telecommunications industry. These details need not be appreciably discussed herein; however shielding is provided, as well as certain conductor path characteristics, including controlled impedance, current carrying capacity, paths for instrument busses, data busses, unit under test stimulus busses, and power busses.
The chassis 60 also defines a cavity 70, the cavity 70 being divided in two by the midplane 68. Thus the midplane 68 separates first and second regions of the housing assembly and thus it is a special form of interior vertical wall that extends between two exterior panels 72 and 76 of the housing. The circuitry of the midplane 68 is well-known in the telecommunications industry. The circuitry details are not appreciably discussed herein except as to assist in understanding the present invention. The switch side 64 is located on one side of the midplane 68, and the port side 69 is located on the other side of the midplane 68. Although the term midplane suggests a location half way between the backplane and the front of the chassis, this is not necessarily the case.
As indicated, the first and second side panels 72 and 76 form exterior walls of the chassis 60 and they extend vertically. The panels 72 and 76 are spaced apart and on opposite sides of the external housing. The switch side 64 is divided into compartments by vertical divider panels or walls 80 and 84 and, optionally, a horizontal divider panel 85 can extend between and connect the panels 80 and 84. The chassis 60 and the various panels can be made with sheet metal, injection molded plastic, or other similarly suited structural materials.
The chassis 60 preferably includes a fan cage 88 in top end section 92 of the housing. The top of the fan cage 88 has eight grill areas 96. The grill areas 96 are designed to permit air to pass in and out of the fan cage 88 while preventing large objects from falling into the fan cage 88. Sides of the fan cage 88 also have grill areas 100. Rails 101 for slidably receiving fan units extend along sides 102 and 103 of the fan cage 88, as well as along central divider 105.
A grill 104 covers and forms an output port 108 located in top end section 92. The dimensions of the output port 108 in one version of the assembly are approximately 4.0 inches by 19.6 inches. At the bottom of the fan cage 88 are fan holders or holding devices 112 for receiving fan units (not illustrated in
As an alternative to using the illustrated type of removable fan units, fixed fans (which are less easily removed) can be provided in the assembly. In this case, the fan holders or fan holding devices would be different than the fan holders 112. The fan holding devices or fan holders for this alternative embodiment could include screws and holes for the screws.
In bottom end section 116 of the chassis 60, there is a first side air input port or switch side air input port 120 and a second side air input port or port side air input port 170. The switch side air input port 120 in one embodiment has a height of approximately 1.5 inches. A grill 124 covers the switch side air input port 120. The grill 124 prevents relatively large sized objects from being sucked into the chassis 60. The air input port can extend across the front of the housing.
In
The electronic apparatuses 130 include circuit boards which interconnect electronic components. The circuit boards for the electronic apparatuses 130 (not illustrated in
Two fan units 140 have been slidably mounted in fan holders or holding devices 144 in the fan cage 88. It will be appreciated that for certain embodiments less than two fans will be adequate; however for the illustrated embodiment a plurality of fans is preferred. For example, a second fan provides redundancy in case of fan failure. The two fan units can be mounted at different heights in the fan cage (as shown).
An output port 148 can span across the width and depth of the two fan units 140 as shown in
The port side air input port 170 is located at the bottom of the chassis and is below electronic apparatuses 130. The port side air input port 170 has a height of approximately 3.4 inches in the illustrated embodiment. The port side air input port 170 is also covered by a grill 174. The grill 174 prevents relatively large sized objects from being sucked into the chassis 60. As shown, the port side input port 170 can extend across the back of the housing.
The switch side 64 is illustrated in
Circuit boards for the electronic apparatuses 180 (not illustrated in
Shown in
The fan unit 140 or 192 can be a fan of variable speed over a wide range of speeds. Optionally, fan speed sensors can be provided to detect fan failure or malfunctioning (e.g. detected speed is 75% or less than desired speed) of one of the fan units 140 or 192, in which case the speed of all of the remaining properly functioning fans can be increased. In other words, fan control means can be provided to selectively adjust the operational speed of the fan unit(s) that has not failed when the other fan has failed or is malfunctioning according to the sensor.
In one embodiment a control module is provided. This control module can control the speed of the fan units 140 and 192. Fan control modules of this type are known to those skilled in the art. U.S. Pat. No. 5,999,403 discloses a control module for varying the speed of a similar type of fan unit.
An output port 200 spans across the width and height of the fan units 192. The output port 200 is adjacent and below the output port 108. The output ports 108 and 200 are equally wide; however the output port 200 has a greater height in the embodiment of
In the embodiment of the equipment assembly illustrated in
If desired, air flow can be directed through an annular fan outlet 221 formed in topside covering 222 of the fan unit instead of through one or more of the vertical sides of the housing 208. This is achieved by covering all of the open vertical sides with baffles. Alternatively, the same effect can be achieved by using an axial type fan instead of a motorized impeller type fan.
In the embodiment illustrated in
It will appreciated that the air flow distribution apparatus of the present invention can be employed in telecommunications equipment assemblies besides core nodes suitable for interfacing with a bi-directional line switched ring and/or routers. The air flow distribution apparatus of the present invention is particularly effective in telecommunications equipment assemblies having dimensions similar to the illustrated embodiment and having power consumption in the range of 4 kW to 4.5 kW.
The telecommunications equipment assembly 230 is attached to a support frame 234 in
There is a space below the equipment assembly 230 suitable for accommodating the attachment of additional equipment to the frame 234. For instance an OM 3500™ sold by Nortel Networks could be attached. Alternatively, another equipment assembly substantially identical to the equipment assembly 230 could be attached. In this last case, the total load weight (not including the frame weight) could be well over 1200 lbs. One skilled in the art will appreciate however that there would rarely be a need to have two core nodes of the type illustrated on the frame 234. The illustrated equipment assembly 230 is currently designed to accommodate traffic for a city having a million people.
A first possible set of air flow paths for the telecommunications equipment assembly 230 is illustrated in
Air flow arrow 266 illustrates air flow through the switch side 64 of the equipment assembly 230. More specifically, air is first sucked in through the switch side air input port 120. This air flow in switch side portion of the bottom plenum region 287 is complemented by air drawn in through the port side inlet 170 and flowing underneath the divider mechanism through the gap G. Air then travels upwardly through the vertical air flow channels between circuit boards 272. Air enters the fan unit 192 through inlet 276 and exits through the output port 200. Top fan outlet 282 of the fan unit 192 can be prevented from exhausting air through the ceiling 262 by suitable closure means known to those skilled in the art. Alternatively, closure means can be provided immediately above the outlet 282. Closure means may not be necessary if the fan unit 192 is a motorized impeller type fan. When the fan unit is the one illustrated in
The portion of the plenum 287 in the switch side 64 is interconnected with the portion of the plenum 287 in the port side 69 because of the gap G. Therefore there is air flow between these portions, such as is indicated by air flow directional arrow 289. The gap G (previously discussed) permits more unequal inlet areas on the port and switch sides than would otherwise be possible. With reference to
Likewise the portion of the plenum 160 in the switch side 64 is interconnected with the portion of the plenum 160 in the port side 69. Therefore there is small air flow between these portions, such as is indicated by air flow directional arrow 288. Air flow between the two plenum portions significantly reduces the impact of a fan fail. In the absence of the plenum region 160 characterized by the interconnected plenum portions, fan failure in the port side 69 would result in non-uniform cooling. In particular, the circuit boards 250 would be less adequately cooled as compared to the circuit boards 272. Likewise fan failure in the switch side 64 would result in the converse non-uniform cooling situation occurring.
The plenum region 160 reduces non-uniform cooling in the event of fan failure in either the switch side 64 or the port side 69. For example, there could be a port side fan failure in which the fan unit 140 would cease to operate. In this case, air flow into the plenum region 160 from the port side 69 which would normally be drawn into the fan unit 140 would instead be drawn into the fan unit 192. Thus the fan unit 192 is able to accommodate cooling of both the switch side 64 and the port side 69.
It will be appreciated that the air flow distribution apparatus of the present invention can be employed to improve air flow distribution regardless of whether the particular telecommunications equipment assembly includes or does not include a midplane. The midplane is simply one preferred way to divide the air flow between the two sides of the telecommunications equipment assembly but other forms of vertical dividers or walls are possible. Furthermore reference in this application to first and second sides in a telecommunications equipment assembly does not imply that telecommunications equipment assembly has both a port and switch side.
In one particular embodiment of the invention, fan failure detection means known to those skilled in the art is provided. Once a fan failure is detected, various responses can occur. First, an indicator light on the exterior of the equipment assembly 230 can be provided to indicate the fan failure. Second, the speed of the fan(s) which have not failed can be increased (assuming that they are not already at their maximum speed). Third, output port(s) of the failed fan can be closed. One skilled in the art will appreciate that doing this prevents unwanted air flow through the output port(s) of the failed fan. Alternatively, louvers can be used over an outlet to prevent inward air flow through the outlet.
A second possible set of air flow paths for the telecommunications equipment assembly 230 is illustrated in
Thus when the telecommunications equipment assembly output ports are configured as illustrated in
A third possible set of air flow paths for the telecommunications equipment assembly 230 is illustrated in
With respect to the switch side 64 of the equipment assembly 230, air flow arrow 306 illustrates air flow through that side. Like in
Thus when the telecommunications equipment assembly output ports are configured as illustrated in
Although
As can be best seen in
Vertically oriented electronic apparatuses 342 and 346 could be the following: 16xOC48s 342 and QUAD 10Gs 346. It will be appreciated by one skilled in the art that the port side electronic apparatuses 342 and 346 are usually covered by clamshells.
There are vertical air flow channels between the electronic apparatuses 342 and 346. Vertical air velocity is greatest in the port side flow channels 347 formed between adjacent pairs of the electronic apparatuses as compared to the other regions illustrated. For both the switch side and the port side, exhaust air velocities can exceed 10 m/s at certain locations in the housing assembly. If there is neighboring equipment, there are various ways of ensuring that the exhaust air does not directly feed this neighboring equipment.
The contour map of
Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described without departing from the scope of the invention, which is defined in the claims.
