RACK IN A STANDALONE MODE

I. Technical Field

[000! S The present disclosure relates generally to cooling compact circuit cards. More particularly, the present disclosure relates to a system and method for cooling circuit cards contained in a rack, server, module or any other form, in a standalone mode.

II. Background

[0002S Conventional thermal management systems for circuit cards (like PCI express, VITA boards etc.) contained in a server, rack, or module-based environment

(referred to interchangeably herein as a "server", "rack", or "module") utilize air coming from fans either inside/embedded within the server/rack enclosure or from an external source. Cool ambient air is pulled from outside the server enclosure and supply it to the server components inside the enclosure, including the circuit cards. Part of the cool air is pushed into the circuit card assembly, and the rest of the cool air is used to cool other server components. Heat sinks or other cooling devices draw heat away from the circuit card assembly and other components, thus cooling the circuit card assembly and other components, thereby heating the air. The heated air is exhausted from the server/rack enclosure.

[0003} According to the ANSI/VITA 48.5 standard, for example, air flow coming from a server environment is used to cool a plug-in unit, e.g., a circuit card assembly. Capacity to the cool the plug-in unit depends on the mass flow allocated to that particular unit when the complete server system is designed. Also, the cooling capacity depends on an air inlet temperature and a mass flow rate as the air is received by the plug-in unit from the server system platform.

[0004] In conventional server/rack cooling systems, the cooling of the circuit cards significantly depends on the total airflow capacity of the server. In such systems, the quantity of air flow received by the circuit cards depends on the flow impedances created due to the other server components. The flow impedances depend on the shape, size, orientation and placement of the other server components. It is difficult to attain proper air flow through the server components and, at the same time, provide a balanced air flow to the circuit card assemblies, which rely solely on the air flow received from the server environment for cooling. Cooling systems designed for the complete server system very often lead to flow imbalances, as the inflow received by the circuit cards may be very low as compared to the total system flow. This creates hot spots and may ultimately result in a component or system failure if the airflow received from the server environment is not adequate.

100051 Attempts to solve the problems associated with cooling circuit cards using conventional server cooling systems include regulating/maximizing the air flow received by the circuit cards from the server by designing ventilation to provide sufficient air flow with a low pressure drop. Also, attempts have been made to optimize the heat sink to reduce the system pressure drop and thereby enhance the air flow velocity to achieve better heat dissipation. Attempts have also been made to reorient/reposition components within the server and the cooling fans to minimize the overall flow impedance of the system. All of these attempts limit overall system reliability and put a lot of constraints of design for the server architecture.

[0006) With the conventional thermal cooling systems, the server manufacturer/designer has to look into various cooling mechanisms when designing the complete system. This is difficult in view o various commercial requirements associated with such systems.

[0007| There is a need for a system that addresses the issues associated with the thermal management of circuit card assemblies cards placed in a server/rack environment which does not depend on the server system air flow for cooling.

III. Summary of the Embodiments

In at least one embodiment, the present disclosure provides a system for cooling a circuit card assembly. A casing encloses the circuit card assembly separately from other components within a rack/server/module. A cooling device is also enclosed within the casing, along with a mechanism for causing ambient air that enters the casing from outside the casing to pass through a channelized path including the circuit card assembly and the cooling device, and exit the casing. The cooling device draws heat from circuit card assembly into air passing through the channelized path, such that the ambient air entering the casing exits the casing and the rack/server/module as heated air.

100081 In at least another embodiment, the present disclosure provides a method for cooling a circuit card assembly enclosed within a casing separately from other components within a rack/server/module. The method comprises causing ambient air that enters the casing from outside the casing to pass through a channelized path including the circuit card assembly and a cooling device enclosed within the casing. The method further comprises causing the ambient air that enters the casing and passes through the channelized path to exit the casing. The cooling device draws heat from the circuit card assembly into air passing through the channelized path, such that the ambient air entering the casing exits the casing and the rack as heated air, thereby causing cooling of the circuit card assembly.

10009 J Further features and advantages, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.

IV. Brief Description of the Drawings

[00i0| Exemplary embodiments may take form in various components and arrangements of components, and in various process operations and arrangements of process operations. Exemplary embodiments are illustrated in the accompanying drawings, throughout which, like reference numerals may indicate corresponding or similar parts in the various figures. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the disclosure. Given the following enabling description of the drawings, the novel aspects of the present disclosure should become evident to a person of ordinary skill in the art.

[001 1] FIGS, 1 A and I B illustrate views of a cooling system in accordance with one embodiment of the present disclosure;

|0012] FIGS, 2A and 2B illustrate views of a cooling system in accordance with another embodiment of the present disclosure;

[00131 FIG. 3 illustrates a process flow diagram of a method for cooling in accordance with an aspect of the present disclosure; and

10014) FIG. 4 illustrates a process flow diagram of a method for cooling in accordance with another aspect of the present disclosure

V. Detailed Description of Embodiments

[0015] While exemplary embodiments are described herein with illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the system and method described herein would be of significant utility.

{0016] According to exemplary embodiments, a cooling system for a circuit card assembly is provided which works independently of a server/rack into which the circuit card assembly may be placed, without relying on the air flow capacity of the server environment. The cooling system includes a casing enclosure enclosing a heat sink assembly (or any other suitable cooling device), a circuit card assembly, and a cooling mechanism, such as a blower, fan, or any other air flow provider or deflector baffle/diverter inline to the air flow. The cooling mechanism may cause ambient air to be pulled into the casing and exhausted as heated air out of the casing and outside the server/rack/module environment to cool the circuit card assembly. The cooling mechanism may also cause ambient air that enters the casing to be blown out of the casing and outside the server/rack module environment as heated air to cool the circuit card assembly. According to an exemplary embodiment, a blower may be preferable, as use of the blower will allow use of a denser heat sink design. The circuit cards referred to herein may include but are not limited to, e.g., Peripheral Component Interconnect (PC!) cards, PCI Express (PCI-X) cards, Versa Module Eurobus (VME) cards, and any other card that is mountable within a rack having any number of slots in any orientation of assembly. It should be appreciated that although the casing encloses the circuit board assembly, heat sink, and cooling mechanism, each of these components may be detachable from the casing.

(0017| Though portions of the circuit card assembly may extend outside of the casing for ease of insertion and extraction of the circuit cards, in the description that follows, the circuit cards that are enclosed within the casing will also be referred to as the circuit card assembly. The cooling system is placed in a server/rack or module- based environment as a stand-alone device, with the casing separating the circuit card assembly from other components outside the casing, such that the circuit card assembly is cooled independently of any cooling that occurs for the other server components outside the casing.

10018] Although not described in detail herein, it should be appreciated that there may be other cards within the server/rack/module, depending on the server requirement, such as Mother boards, power supply units, hard disks and other various cards/components/parts. These cards may or may not dissipate heat but constitute significant space.

|0019j FIGS. 1 A and 1 B illustrate views of a cooling system in accordance with a one embodiment of the present disclosure. Referring to FIG. 1 A, a casing 100 encloses a circuit card assembly 105. The casing 100 also encloses a heat sink assembly 150 and a mechanism 160 for pulling/drawing ambient air into the casing and exhausting/pushing hot air out of the casing. The mechanism 160 may include, e.g., a blower, a fan, or a combination thereof. The casing 100 may be placed into a server/rack module such that the casing separates the circuit card assembly 105, the heat sink assembly 150, and the mechanism 160 from other components included within the server rack module. |0020| The server/rack module is not shown in the interest of simplifying the illustration. The casing 100 may be made, e.g., of metal for optimal cooling. However, it should be appreciated that the casing 100 may also be made of other materials, e.g., plastic. The heat sink assembly 150 may also be made of metal, e.g., aluminum, copper or any other material with or without plating.

{00211 According to the embodiment shown in FIGS. 1 A and I B, an incoming ambient air flow 130 from outside the casing 100 enters the casing, flows through a channelized path including the circuit card assembly 105 and the heat sink assembly 150, and is sucked into the mechanism 160 and exhausted by the mechanism to the atmosphere outside the casing. As the heat sink assembly 150 is completely enclosed inside the casing 100, flow bypass of the incoming ambient air may be avoided in many cases, depending on design constraints. The casing 100 not only acts to enclose the circuit card assembly 105, the heat sink assembly 150, and the mechanism 160 but may also acts a heat spreader, so that the passing air will take away the heat from the components and other hot spots within the casing.

10022] According to an exemplary embodiment, the casing 100 may include two chambers 1 10 and 120, separated by a wall 102. The chambers may be arranged adjacent to each other, as shown in FIG. 1 A. It should be appreciated that two chambers are shown for illustrative purposes but than a single chamber or more than two chambers may be used.

|0023| Referring again to FIG. 1 A, the first chamber 1 10 houses the heat sink assembly 150. The second chamber 120 houses the mechanism 160. The circuit board assembly 105 may be housed in either or both of the chambers 1 10 and 120. According to a first aspect, ambient air enters the casing 100 and flows through the channelized path, including the circuit card assembly 105 and the heat sink assembly 150, until the air reaches a suction end of the mechanism 160. The heat sink assembly 150 draws heat away from the circuit card assembly 105 into the air flow, thereby cooling the circuit board assembly 105 but heating the air. Thus, when the air flow reaches the mechanism 160, the air has become hot. The mechanism 160 sucks in the hot air and exhausts it from the casing 100 into the atmosphere. This airflow path created due to the mechanism 160 along with casing 100 of incoming ambient air and exhausting hot air will be continuous, thus maintaining the cooling effect of the system.

10024] FIG. I B depicts a similar arrangement as that shown in FIG. 1 A, with a front plate 103 of the casing 100 pulled away from the casing for ease of illustration. According to one embodiment, ambient air enters the first chamber 1 10 of the casing through one set of vents 1 15 included on the front plate 103. Hot air is exhausted from the second chamber 120 of the casing through a different set vents 125 on the front plate 103, thereby cooling the circuit card assembly 105 without utilizing air coming from server/rack or module into which the casing is placed. Though vents are illustrated as an example of openings that may allow air to enter into and flow out of the casing, it should be appreciated that any other type of opening, such as louvers, grilles, etc., may be used.

[0025] Although not shown in the interest of simplifying illustration, it should be appreciated that, according to a different aspect of the disclosure, the direction of the air flows 130 and 140 may be reversed. According to this aspect, the mechanism 160 sucks ambient air from outside the casing 100 into the casing via the vents 125, and blows the air out, pushing it through the channelized path, including the heat sink assembly 150 and the circuit board assembly 105, and outside of the casing 100 via the vents 1 15.

10026] Similar to the aspect described above with reference to FIGS. 1 A and 1 B, the heat sink assembly 150 draws heat away from the circuit board assembly 105, thus cooling the circuit card assembly 105 but heating the air flow. As the mechanism 160 sucks more ambient air into the casing and blows it out of the casing, this causes the hot air to be pushed outside of the casing, thereby maintaining the cooling effect of the system.

10027] FIGS. 2A and 2B illustrate views of a cooling system in accordance with a another embodiment of the present disclosure. The embodiment shown in FIGS. 2A and 2B is similar to that shown FIGS. 1 A and I B, except that a casing 200 is split into two chambers 210 and 220 that are vertically arranged. For example, as shown in FIGS. 2A and 2B, chamber 210 is arranged below chamber 220, separated by a wall 202. It should be appreciated, however, that chamber 220 may instead be arranged below chamber 210.

|0028] Referring to FIG. 2A, the casing 200 encloses a circuit card assembly 205, a heat sink assembly 250, and a mechanism 260. The first chamber 210 houses the circuit card assembly 205 and the heat sink assembly 250, and the second chamber 220 houses the mechanism 260. According to one aspect as illustrated in FIG. 2A, an incoming air flow 230 flows into the casing 200 and through a channelized path, including the circuit card assembly 205 and the heat sink assembly 250, until the air reaches a suction end of the mechanism 260.

[0029] The heat sink assembly 250 draws heat away from the circuit card assembly 205 into the air flow, thereby cooling the circuit board assembly 205 but heating the air. Thus, when the air flow reaches the mechanism 260, the air has become hot. The mechanism 260 sucks in the hot air and exhausts it into the atmosphere as an outgoing air flow 240. This airflow path created due to mechanism 260 along with casing 200 of incoming ambient air and exhausting hot air will be continuous, thus maintaining the cooling effect of the system.

[0030) FIG. 2B depicts a similar arrangement as that shown in FIG. 2A, with a front plate 203 of the casing 200 pulled away from the casing for ease of illustration. According to one embodiment, ambient air enters the chamber 210 of the casing through one set of vents 215 included on the front plate 203. Hot air is exhausted from the second chamber 220 of the casing through a different set of vents 225 on the front plate 203, thereby cooling the circuit card assembly 205 without utilizing the air coming from server/rack or module. Similar to FIG. 1 B, though vents are illustrated in FIG. 2B as an example of openings that may allow air to enter into and flow out of the casing, it should be appreciated that any other type of opening, such as louvers, grilles, etc., may be used. [00 11 Although not shown in the interest of simplifying illustration, it should be appreciated that, according to a different aspect of the disclosure, the direction of the air flows 230 and 240 may be reversed. According to this aspect, the mechanism 260 sucks ambient air from outside the casing 200 into the casing via the vents 225, and blows the air through the channelized path, including the heat sink assembly 250 and the circuit board assembly 205, and outside of the casing 200 via the vents 215.

10032] Similar to the aspect described above, the heat sink assembly 250 draws heat away from the circuit board assembly 205, thus cooling the circuit board assembly 205 but heating the air flow. As the mechanism 260 sucks in more ambient air into the casing and blows it out of the casing, this causes the hot air to be pushed outside of the casing, thereby maintaining the cooling effect of the system.

10033) FIG. 3 illustrates a process flow diagram of a method for cooling a circuit card assembly in accordance with one aspect of the present disclosure. Referring to FIG. 3, the process begins at step 310 at which an incoming air flow of ambient air enters the casing 100, 200. At step 320, the ambient air is drawn through a channelized path, including the circuit card assembly 105, 205 and the heat sink assembly 150, 250. At step 330, air heated by dissipation of heat from the circuit card assembly 105, 205 to the heat sink assembly 150, 250 is sucked in by the mechanism 160, 260. At step 340, the hot air is exhausted from the casing 100, 200, thereby maintaining a cooling effect for the circuit card assembly 105, 205.

[0034] FIG. 4 illustrates a process flow diagram of a method for cooling a circuit card assembly in accordance with another aspect of the present disclosure. Referring to FIG. 4, the process begins at step 410 and which ambient air is sucked into the casing 100, 200 by the mechanism 160, 260. At step 420, the ambient air is pushed out of the mechanism to the channelized path within the casing. At step 430, the ambient air is pushed through the channelized path, including the heat sink assembly 150, 250 and the circuit card assembly 105, 205. At step 440, air heated by dissipation of heat from the circuit card assembly 105, 205 to the heat sink assembly 150, 250, flows out of the casing 100, 200, thereby maintaining a cooling effect often circuit card assembly 105, 205. [0035] According to exemplary embodiments, the cooling system and method for cooling described herein provide uniform air flow and equal cooling across the heat sink, with a minimum pressure drop. Since only ambient air is used, and no air from the server/rack is used for cooling, the cooling system may be a standalone device. Thus, the risk of failure of the circuit cards due to low air flow from the server/rack/module can be minimized to almost zero.

10036) As the cooling system and method described herein operates independently of any cooling system provided in the server/rack module, the designer of the server/rack/module will be under fewer constraints in designing the server/rack module. The designer need not worry about thermal management of the circuit card assembly when designing the server/rack/module.

[0037] Alternative embodiments, examples, and modifications which would still be encompassed by the disclosure may be made by those skilled in the art, particularly in light of the foregoing teachings. Further, it should be understood that the terminology used to describe the disclosure is intended to be in the nature of words of description rather than of limitation.

[0038] Those skilled in the art will also appreciate that various adaptations and modifications of the preferred and alternative embodiments described above can be configured without departing from the scope and spirit of the disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the disclosure may be practiced other than as specifically described herein.