WO1986006574A1 - Improvements in or relating to air ducts - Google Patents

Improvements in or relating to air ducts Download PDF

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Publication number
WO1986006574A1
WO1986006574A1 PCT/GB1986/000233 GB8600233W WO8606574A1 WO 1986006574 A1 WO1986006574 A1 WO 1986006574A1 GB 8600233 W GB8600233 W GB 8600233W WO 8606574 A1 WO8606574 A1 WO 8606574A1
Authority
WO
WIPO (PCT)
Prior art keywords
air duct
extruded
section
cabinet
air
Prior art date
Application number
PCT/GB1986/000233
Other languages
French (fr)
Inventor
Martin John Russell
Original Assignee
Plessey Overseas Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Plessey Overseas Limited filed Critical Plessey Overseas Limited
Publication of WO1986006574A1 publication Critical patent/WO1986006574A1/en

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K7/00—Constructional details common to different types of electric apparatus
    • H05K7/20—Modifications to facilitate cooling, ventilating, or heating
    • H05K7/20536—Modifications to facilitate cooling, ventilating, or heating for racks or cabinets of standardised dimensions, e.g. electronic racks for aircraft or telecommunication equipment
    • H05K7/206—Air circulating in closed loop within cabinets wherein heat is removed through air-to-air heat-exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L9/00—Rigid pipes
    • F16L9/02—Rigid pipes of metal
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
    • H02G3/02—Details
    • H02G3/03—Cooling

Definitions

  • the present invention relates to air ducts and more particularly to an air duct for use as part of a cooling system for a cabinet.
  • PCBS printed circuit boards
  • the cooling system is required to prevent the internal temperature of the cabinet exceeding a maximum value which may give rise to an unacceptable change in the operating parameters of the electronic equipment.
  • One type of such cabinet makes use of an air cooling system in which cold air is allowed to circulate within the cabinet to cool the equipment, the resultant warm air being channelled along an air duct to a heat exchanger for cooling the air prior to its recirculation. Additional cooling of the cabinet may be effected by providing in the vicinity of the air duct a plurality of spaced parallel tubes through which liquid coolant is fed.
  • X-rays of the aluminium castings have been found to be required to ensure that no blow holes have been created during the casting process.
  • the difficulty arising from the porosity of the aluminium casting can be overcome by suitable impregnation techniques and the consistent wall thickness can to some extent be overcome by machining techniques but these remedial measures are both expensive, time consuming and the final product may in the end be rejected as not meeting the desired physical characteristics as regards design stress level and surface finish.
  • An objective of the present invention is to provide an air duct cooling system which has an enhanced design stress level and which can be manufactured with consistent wall thickness, profile and a high quality surface finish.
  • an extruded air duct for use as part of a cabinet cooling system, the extruded air duct having a rigid section and a permissible shock design stress of at least 150mPa.
  • permissible shock design stress is defined by the equation:-
  • the material from which the extruded air duct is manufactured is aluminium.
  • the extruded air duct comprises two sections one of which is extruded and the other of which is a machined plate, the extruded section has a transverse cross-section of non-linear configuration and the machined plate has a transverse cross-section of substantially linear configuration, each section having a respective shape and size to allow both sections to be easily assembled together to define the extruded air duct.
  • the machined plate incorporates a channel along which a liquid coolant may be fed.
  • the extruded section is provided with a pair of shoulders for abutting against a surface of the machined plate when the two sections are assembled together to define the air duct.
  • the present invention also provides a cabinet cooling system, the cabinet cooling system comprising an extruded air duct having a rigid section and a permissible shock design stress of at least 150 MPa, an outlet of the extruded air duct being coupled to a heat exchanger for cooling air from the air duct, and means being provided for creating a flow of air from the heat exchanger through an internal zone of the cabinet to an inlet port of the air duct.
  • each air duct is located along a respective side of a receptacle mounted within the cabinet, each air duct having its outlet port coupled to the heat exchanger which is positioned at one end of the receptacle, the inlet ports of the air ducts being coupled to a fan arrangement located at the opposite end of the receptacle.
  • Figure 1 is a section of a casting for use as an air duct in a cabinet cooling system not in accordance with the present invention
  • Figure 2 is a sectional view of an extrusion suitable for use in forming an integral part of an air duct in accordance with an embodiment of the present invention
  • Figure 3 is an inside perspective of the extrusion of Figure 2;
  • Figure 4 is an outside perspective of the extrusion of Figure 2;
  • Figure 5 is a sectional view of an air duct in accordance with an embodiment of the present invention
  • Figure 6 is a view of a cabinet having a receptacle incorporating the air duct of Figure 5.
  • FIG. 1 of the drawings there is illustrated a section through an aluminium casting which is cast as one piece and which is designed for use as an air duct in a cabinet cooling system.
  • the casting defines within its body a conduit 2 for the passage of air therethrough and defines also four parallel spaced apart tubes 4 through which a liquid coolant may be passed.
  • Casting techniques have the advantage that air ducts of large physical sizes and lengths can be manufactured to meet the requirements of cabinet cooling systems, particularly for those cooling systems associated with cabinets for housing electronic equipment. As stated earlier there are however a number of significant disadvantages with cast materials which make them unsuitable for use as air ducts without expensive and time consuming processes also being applied subsequent to the casting process.
  • an extrusion of sufficiently long length and width to enable the extrusion to be used as part of an air duct.
  • FIGs 2, 3 and 4 there is illustrated an aluminium extrusion 6 in accordance with one embodiment of the present invention.
  • the extrusion 6 has a design configuration as shown which exhibits a permissible shock design stress of at least 150 MPa.
  • a pair of shoulders 8 are provided which protrude inwardly of the extrusion body, the shoulders 8 having flat faces 10 for abutment with and securing to the flat surface of a second section ( Figure 5) to form together the extruded air duct.
  • Figure 5 there is illustrated a sectional view of an air duct 12 in accordance with an embodiment of the present invention.
  • the air duct 12 consists of the aluminium extrusion 6 of Figure 2 assembled to an elongate substantially planar aluminium machine plate 14.
  • a top face 16 of the machined plate 14 has an elongate area adjacent each edge in abutting relationship with the flat elongate faces 10 of the shoulders 8, and are secured thereto by a suitable fixing arrangement.
  • a conduit for the air is defined between an inner face 18 of the extrusion 6 and the top face 16 of the machined plate 14.
  • the machined plate 14 is provided with one or more channels (not shown) through which coolant liquid may be passed.
  • FIG. 6 there is illustrated a front view of a cabinet 20 housing a receptacle 22.
  • the receptacle 22 is pivotally mounted within the cabinet 20.
  • Two air ducts 12 like those of Figure 5 form an integral part of the receptacle 22 and extend down its opposite side faces.
  • Each of the air ducts 12 has an outlet port which is coupled to a heat exchanger housed in a base casting 24 of the receptacle 22.
  • Each of the air ducts 12 also has an inlet port which is coupled to a fan arrangement located in a top casting 26.
  • the base casting 24 and the top casting 26 are manufactured from aluminium and are formed as an integral structure with the air ducts 12 being connected to the castings 24, 26.
  • the cabinet cooling system induces a cold air flow from the heat exchanger up through the inside of the receptable 22 to the fan arrangement at the top.
  • the warm air passes through the inlet ports of the air ducts 12, down the air ducts 12 and out through their outlet ports to the heat exchanger. In this way rising cold air can be used to cool any electronic equipment housed within the receptacle 22.
  • extrusions provide a consistent profile and wall thickness, an improved strength over the cast design and a high quality surface finish.
  • the higher standard of surface finish results in not only a reduction in air turbulence thereby a better thermal performance but provides an ideal surface for the paint finish.
  • the consistent profile and wall thickness are fundamental to processes used for structural interface.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Mechanical Engineering (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)

Abstract

An air duct (12) for use as an integral part of a cabinet cooling system. The extruded air duct has a rigid section constructed from two parts and has a permissible shock design stress of at least 150 MPa.

Description

-1-
IMPROVEMENTS IN OR RELATING TO AIR DUCTS
The present invention relates to air ducts and more particularly to an air duct for use as part of a cooling system for a cabinet.
It is known that certain types of cabinets which are designed to house electronic equipment, such as printed circuit boards (PCBS), may have to be provided with a cooling system. The cooling system is required to prevent the internal temperature of the cabinet exceeding a maximum value which may give rise to an unacceptable change in the operating parameters of the electronic equipment. One type of such cabinet makes use of an air cooling system in which cold air is allowed to circulate within the cabinet to cool the equipment, the resultant warm air being channelled along an air duct to a heat exchanger for cooling the air prior to its recirculation. Additional cooling of the cabinet may be effected by providing in the vicinity of the air duct a plurality of spaced parallel tubes through which liquid coolant is fed. Difficulties arise in the fabrication of such cooling systems when there are constraints on the materials which are to be used and constraints on other physical characteristics associated with the cooling system and cabinet. We have found, for example, that an aluminium casting incorporating within its design an air duct and channels through which liquid coolant is to be fed gives rise to a variety of problems. The aluminium casting is porous resulting in"-leakage of coolant, it is difficult to obtain by a casting technique consistent profiles of wall thickness and a smooth surface for the air duct and channels which in turn give rise to unwanted turbulence of the flows of air and liquid coolant within the air duct and coolant channels respectively. Furthermore many
X-rays of the aluminium castings have been found to be required to ensure that no blow holes have been created during the casting process. The difficulty arising from the porosity of the aluminium casting can be overcome by suitable impregnation techniques and the consistent wall thickness can to some extent be overcome by machining techniques but these remedial measures are both expensive, time consuming and the final product may in the end be rejected as not meeting the desired physical characteristics as regards design stress level and surface finish.
An objective of the present invention is to provide an air duct cooling system which has an enhanced design stress level and which can be manufactured with consistent wall thickness, profile and a high quality surface finish. According to the present invention there is provided an extruded air duct for use as part of a cabinet cooling system, the extruded air duct having a rigid section and a permissible shock design stress of at least 150mPa.
The term permissible shock design stress is defined by the equation:-
Permissible shock design stress =
static ultimate tensile stress] x dynamic proof stress static proof stress /
It will be appreciated that the static ultimate tensile stress, the static proof stress and the dynamic proof stress are dependent on the type of material used, the wall thicknesses and configurations employed.
In a preferred embodiment the material from which the extruded air duct is manufactured is aluminium. In one embodiment the extruded air duct comprises two sections one of which is extruded and the other of which is a machined plate, the extruded section has a transverse cross-section of non-linear configuration and the machined plate has a transverse cross-section of substantially linear configuration, each section having a respective shape and size to allow both sections to be easily assembled together to define the extruded air duct. In a preferred embodiment the machined plate incorporates a channel along which a liquid coolant may be fed.
In one embodiment the extruded section is provided with a pair of shoulders for abutting against a surface of the machined plate when the two sections are assembled together to define the air duct.
The present invention also provides a cabinet cooling system, the cabinet cooling system comprising an extruded air duct having a rigid section and a permissible shock design stress of at least 150 MPa, an outlet of the extruded air duct being coupled to a heat exchanger for cooling air from the air duct, and means being provided for creating a flow of air from the heat exchanger through an internal zone of the cabinet to an inlet port of the air duct.
In a preferred embodiment two air ducts are provided each of which is located along a respective side of a receptacle mounted within the cabinet, each air duct having its outlet port coupled to the heat exchanger which is positioned at one end of the receptacle, the inlet ports of the air ducts being coupled to a fan arrangement located at the opposite end of the receptacle.
The present invention will be described further, by way of example, with reference to the accompanying drawings in which:
Figure 1 is a section of a casting for use as an air duct in a cabinet cooling system not in accordance with the present invention; Figure 2 is a sectional view of an extrusion suitable for use in forming an integral part of an air duct in accordance with an embodiment of the present invention;
Figure 3 is an inside perspective of the extrusion of Figure 2; Figure 4 is an outside perspective of the extrusion of Figure 2;
Figure 5 is a sectional view of an air duct in accordance with an embodiment of the present invention; and, Figure 6 is a view of a cabinet having a receptacle incorporating the air duct of Figure 5.
Referring to Figure 1 of the drawings there is illustrated a section through an aluminium casting which is cast as one piece and which is designed for use as an air duct in a cabinet cooling system. The casting defines within its body a conduit 2 for the passage of air therethrough and defines also four parallel spaced apart tubes 4 through which a liquid coolant may be passed.
Casting techniques have the advantage that air ducts of large physical sizes and lengths can be manufactured to meet the requirements of cabinet cooling systems, particularly for those cooling systems associated with cabinets for housing electronic equipment. As stated earlier there are however a number of significant disadvantages with cast materials which make them unsuitable for use as air ducts without expensive and time consuming processes also being applied subsequent to the casting process.
We have found surprisingly that it is practical to manufacture an extrusion of sufficiently long length and width to enable the extrusion to be used as part of an air duct. Furthermore, we have found that it is possible to design such extrusions and air ducts so as to exhibit a permissible shock design stress of at least 150MPa. Referring to Figures 2, 3 and 4 there is illustrated an aluminium extrusion 6 in accordance with one embodiment of the present invention. The extrusion 6 has a design configuration as shown which exhibits a permissible shock design stress of at least 150 MPa. A pair of shoulders 8 are provided which protrude inwardly of the extrusion body, the shoulders 8 having flat faces 10 for abutment with and securing to the flat surface of a second section (Figure 5) to form together the extruded air duct.Referring to Figure 5 there is illustrated a sectional view of an air duct 12 in accordance with an embodiment of the present invention. The air duct 12 consists of the aluminium extrusion 6 of Figure 2 assembled to an elongate substantially planar aluminium machine plate 14. A top face 16 of the machined plate 14 has an elongate area adjacent each edge in abutting relationship with the flat elongate faces 10 of the shoulders 8, and are secured thereto by a suitable fixing arrangement. A conduit for the air is defined between an inner face 18 of the extrusion 6 and the top face 16 of the machined plate 14. The machined plate 14 is provided with one or more channels (not shown) through which coolant liquid may be passed.
Referring to Figure 6 there is illustrated a front view of a cabinet 20 housing a receptacle 22. The receptacle 22 is pivotally mounted within the cabinet 20. Two air ducts 12 like those of Figure 5 form an integral part of the receptacle 22 and extend down its opposite side faces. Each of the air ducts 12 has an outlet port which is coupled to a heat exchanger housed in a base casting 24 of the receptacle 22. Each of the air ducts 12 also has an inlet port which is coupled to a fan arrangement located in a top casting 26. The base casting 24 and the top casting 26 are manufactured from aluminium and are formed as an integral structure with the air ducts 12 being connected to the castings 24, 26. In operation the cabinet cooling system induces a cold air flow from the heat exchanger up through the inside of the receptable 22 to the fan arrangement at the top. The warm air passes through the inlet ports of the air ducts 12, down the air ducts 12 and out through their outlet ports to the heat exchanger. In this way rising cold air can be used to cool any electronic equipment housed within the receptacle 22.
By adopting an aluminium extrusion 6 as described above as opposed to aluminium castings one is able to eliminate porosity, the need to impregnate and the need to employ 'X' rays to check for blow holes. Furthermore, extrusions provide a consistent profile and wall thickness, an improved strength over the cast design and a high quality surface finish. The higher standard of surface finish results in not only a reduction in air turbulence thereby a better thermal performance but provides an ideal surface for the paint finish. The consistent profile and wall thickness are fundamental to processes used for structural interface.
Although the present invention has been described with respect to a particular embodiment, it should be understood that modifications may be effected within the scope of the invention. For example, although the extrusion material used in the above embodiment is aluminium, which is by far the preferred material, it may be possible to obtain the permissible shock design stress by means of certain types of plastics materials.

Claims

CLAIMS :
1. An extruded air duct for use as part of a cabinet cooling system, the extruded air duct having a rigid section and a permissible shock design stress as hereinbefore defined of at least 150 MPa.
2. An extruded air duct as claimed in claim 1 wherein the extruded air duct is manufactured from aluminium.
3. An extruded air duct as claimed in claim 1 or claim 2 wherein the extruded air duct comprises two sections, one of which is extruded and has a transverse cross-section of non-linear configuration and the other of which is a machined plate and has a transverse cross-section of substantially linear configuration, each section having a respective shape and size to allow both sections to be easily assembled together to define the extruded air duct.
4. An extruded air duct as claimed in claim 3 wherein said the extruded section is provided with a pair of shoulders for abutting against a surface of the machined plate when the sections are assembled together to define the extruded air duct.
5. A cabinet cooling system comprising an extruded air duct as claimed in any one of claims 1 to 4 wherein an outlet of the extruded air duct is coupled to a heat exchanger for cooling air from the air duct, and means are provided for creating a flow of air from the heat exchanger through an internal zone of the cabinet to an inlet port of the air duct.
6. A cabinet cooling system as claimed in claim 5 wherein two air ducts are provided each of which is located along a respective side of a receptacle mounted within the cabonet, each air duct having its outlet port coupled to the heat exchanger which is positioned at one end of the receptacle, the inlet ports of the air ducts being coupled to a fan arrangement located at the opposite end of the receptacle.
PCT/GB1986/000233 1985-05-02 1986-05-01 Improvements in or relating to air ducts WO1986006574A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB858511198A GB8511198D0 (en) 1985-05-02 1985-05-02 Air duct extrusion
GB8511198 1985-05-02

Publications (1)

Publication Number Publication Date
WO1986006574A1 true WO1986006574A1 (en) 1986-11-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1986/000233 WO1986006574A1 (en) 1985-05-02 1986-05-01 Improvements in or relating to air ducts

Country Status (3)

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EP (1) EP0221125A1 (en)
GB (2) GB8511198D0 (en)
WO (1) WO1986006574A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29512979U1 (en) * 1995-08-13 1995-11-23 Bode Manfred Housings for electronic components

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6112542A (en) * 1998-12-15 2000-09-05 Daewoo Electronics Co., Ltd. Refrigerator having a cooled-air passageway formed with an external surface of a liner

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4485429A (en) * 1982-06-09 1984-11-27 Sperry Corporation Apparatus for cooling integrated circuit chips

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4485429A (en) * 1982-06-09 1984-11-27 Sperry Corporation Apparatus for cooling integrated circuit chips

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29512979U1 (en) * 1995-08-13 1995-11-23 Bode Manfred Housings for electronic components

Also Published As

Publication number Publication date
GB2174487B (en) 1989-10-04
GB2174487A (en) 1986-11-05
EP0221125A1 (en) 1987-05-13
GB8610678D0 (en) 1986-06-04
GB8511198D0 (en) 1985-06-12

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