Heat exchange – Heat transmitter
Reexamination Certificate
2000-01-26
2002-04-02
Lazarus, Ira S. (Department: 3743)
Heat exchange
Heat transmitter
C165S080300, C361S697000, C174S016300, C257S719000, C454S184000
Reexamination Certificate
active
06364009
ABSTRACT:
The present invention relates to a cooling apparatus, in particular, but not exclusively, to a cooling apparatus for cooling an electrical device.
The invention relates more particularly to electrical devices which perform a processing or memory function, such as any processor (for example a semiconductor or other logic device, an integrated circuit, a microprocessor and the like) or any storage device (for example a mass storage device). Such devices may be in the form of an integrated circuit, possibly mounted on a printed circuit board (PCB). Accordingly, the electrical device may be for electrical equipment, which may typically be a computer, modem, switch, hub or like equipment.
Electrical devices usually generate heat during use. During use, the device may become warm. It is undesirable for the device to become too hot because excessive heat can cause damage to components of the device.
It is known to cool electrical devices in electrical equipment using one or more fans and indeed a cooling fan is often provided in electrical equipment. In a conventional arrangement, electrical devices are arranged within a casing, the fan sucks air through one or more vents in the casing, the air passes over the devices and out of the casing via the fan.
To improve the cooling, heatsinks may be provided on the upper surface of the devices to draw heat away from the device. Conventionally, such heatsinks comprise one or more metal formations attached to the top of the device. The heatsink may comprise vertical fins attached to the upper surface of the device.
However, under many conditions, such arrangements have been found to be inefficient.
It is an object of the present invention to improve the cooling of the electrical device and/or to improve the efficiency of the cooling. One benefit of improving the efficiency of the cooling is that smaller and/or fewer fans could be used to obtain the desired cooling effect.
Furthermore, it has been realised pursuant to the present invention that, in many situations, some of the devices in an item of electrical equipment require more cooling than other devices. In order to cool such equipment sufficiently, a high air flow through the equipment is required. Other devices which require little or no cooling are also subject to the high air flow unnecessarily.
According to a first aspect of the present invention, there is provided a cooling apparatus for cooling an electrical device using a flow of coolant, the apparatus comprising a cooling unit for contact with the device, the cooling unit including a channel for transporting the coolant past the device.
By providing a channel for the flow of coolant past the device, the cooling of the device may be controlled, and can be made more efficient. Thus the efficiency of the cooling apparatus may be increased.
As used herein, it should be understood that the term “channel” should be interpreted broadly to include any passage or channel along which the flow of the coolant may be directed. The term is not restricted to fully enclosed structures (as for example a tube), but also includes structures which are not fully enclosed. The flow of the coolant might be enclosed only on three sides or on two sides: the channel may comprise three surfaces or only two surfaces. It is envisaged that the channel may only comprise a single surface but that surface may serve to effect the desired flow of coolant.
Preferably, the channel comprises an enclosed structure, for example a tube or passageway. Preferably the flow of coolant is enclosed on at least three sides within the channel. In some embodiments of the invention, it will be preferable for the flow of coolant to be enclosed on all sides within the channel.
Preferably, the cooling unit is adapted to increase the flow velocity of the coolant past the device. By increasing the flow velocity, the rate and thus efficiency of cooling of the device can be increased. Thus the same cooling of the device can be achieved using fewer and/or smaller coolant devices, for example fans.
In a preferred embodiment of the invention, the sectional area of the channel varies between the inlet and the outlet of the channel. As the sectional area decreases, the velocity of the coolant, and thus its cooling effect increases.
The sectional area of the channel may decrease linearly from the inlet. Alternatively, a constriction may be formed in the channel, for example corresponding to an area of the device which requires greatest cooling.
Where the area of the channel is reduced in such a way, preferably the channel further includes a diffuser at the outlet of the channel to recover the pressure head and thus improve efficiency. The diffuser is a passage which gradually increases in sectional area downstream and its function is to reduce the velocity of the coolant to recover its head, or at least to attempt to retain the head.
The term “sectional area” preferably refers to a transverse cross section of the channel being substantially perpendicular to the direction of the flow of coolant at that location. Furthermore, unless clear to the contrary from the context “length” preferably refers to a distance substantially parallel to the direction of flow of the coolant, and width preferably refers to a dimension being substantially perpendicular to the “length” and parallel to the upper surface of the device, where appropriate.
Preferably, the cooling unit comprises a directing formation for directing the coolant towards the device. By directing the coolant towards the device, the cooling of the device can be increased.
The directing formation may be provided by a wall of the channel or may include a separate formation, which may be located in the channel or outside the channel.
Preferably, the directing formation comprises a directing surface, the surface being adapted to be angled relative to the direction of the coolant flow. Thus the coolant flow is deflected towards the device, thus increasing the efficiency of the cooling.
Preferably, the directing surface is adapted to be at an angle of between 5° and 85° to the direction of the coolant flow. In a preferred embodiment, the angle is between 5° and 10°. The angle may be less than 45°, 30° or 15°.
The directing surface may comprise a planar surface or may be curved, depending on the size and type of device to be cooled. A curved directing surface will usually be preferred having regard to the flow of the coolant through the channel. Furthermore, the shape of the directing surface can be adapted so as to direct coolant to specific hot areas of the device.
The size of the cooling unit will be chosen having regard to the size of the device or devices to be cooled. In some embodiments, the height of the cooling unit will be similar to the width of the cooling unit. The width of the cooling unit will, for some embodiments, be chosen to be the same as that of the device to be cooled.
Alternatively, the cooling unit may be smaller than or larger than the device; the cooling unit may extend beyond a surface of the device in one or more directions. Indeed, the cooling unit may extend over more than one device.
Preferably, the apparatus further includes a turbulence formation for generating turbulent flow of the coolant. Turbulent flow gives improved heat transfer from the device and therefore increased cooling. Turbulence may be effected, for example, by increasing the velocity of the coolant flow and/or providing raised areas on the surfaces of the channel. The turbulence may be localised in specific regions of the channel. The turbulence formation may comprise one or more protrusions.
Preferably, the apparatus further includes cooling fins. The cooling fins can increase the turbulence of the coolant flow. Furthermore, the cooling fins provide an increased surface area of the cooling apparatus and thus improved convection of heat from the apparatus. Cooling fins are preferably provided on the inner and/or the outer surfaces of the channel.
Preferably, the walls of the channel are profiled to increase their surface area.
In a preferred embodime
Foley Nicholas
Fryers Bruce
MacManus Gerard
Tate Michael
3Com Corporation
Lazarus Ira S.
Michaelson Peter L.
Michaelson & Wallace
Skafar Janet M.
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