Cooling system for removing heat from an object

Details Cooling system for removing heat from an object Cooling system for removing heat from an object

2001-02-07

2002-10-01

Thompson, Gregory (Department: 2835)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C165S080300, C165S122000, C165S185000, C257S722000

Reexamination Certificate

active

06459580

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to cooling systems for facilitating the removal of heat from a variety of objects, and particularly to a technique that utilizes a combined heat sink and fan.
BACKGROUND OF THE INVENTION
In a variety of products and applications, it is beneficial to remove heat from certain objects or areas. For,example, electronic devices, such as computers, servers, cameras, projectors, etc. often have heat producing components, such as processors or other microchips that generate heat. To ensure the desired operation and life of the component or overall device, it often is necessary or beneficial to cool such components.
Many types of heat sinks have been used to facilitate the removal of heat from a given object. Heat sinks often include a plurality of fins that increase the rate at which heat is transferred from the object and dissipated to the environment. In some applications, fans are used to circulate air in the vicinity of the heat sink to promote a greater rate of heat transfer from the heat sink to the surrounding environment.
Additionally, active heat sinks have been employed that utilize an axial fan dedicated to a specific heat sink. The axial fan is mounted to the heat sink or proximate the heat sink for providing a dedicated airflow over the heat sink. In a typical embodiment, an axial fan is mounted proximate the distal ends of heat transfer fins and air is directed along the heat transfer fins towards the base of the heat sink.
However, whether this particular arrangement or others are used, existing active heat sinks are subject to a variety of problems that inhibit desired removal of heat. For example, axial fans are susceptible to backpressure. When backpressure builds, the airflow effectively stops. This reduction or stoppage of airflow is problematic, because increases in the amount of heat removed from the heat sink is directly related to the velocity of the air flow induced by the fan. Additionally, axial fans expel air in a circular or twisting motion due to the rotational movement of fan blades that extend radially outward from a center axis or hub. This arrangement leaves a “dead zone” extending axially outward from the hub, e.g. along the axis, of the fan. The air expelled by the fan blades moves in the circular or twisting motion around this dead zone.
When the fan is positioned adjacent the heat transfer fins of a heat sink, this dead zone often is disposed generally at the center of the heat sink which typically is the area of greatest heat generation. Also, the circulating or twisting air tends to move laterally against the heat transfer fins. The fins interrupt or stall the movement of the air creating stagnant air between the heat transfer fins. Furthermore, the airflow tends to take the path of least resistance which is outward through the sides of the fins rather than to the center surface of the heat sink. Whether due to backpressure, outflow of air, occurrence of the dead zone or blockage of the circulating airflow by the heat transfer fins, reduced or stalled airflow across the heat sink base and heat transfer fins substantially inhibits the removal of heat from a given object.
Another problem with certain types of fans, such as axial fans is the acoustical output, i.e., noise. As the flow capacity requirements increase, to combat backpressure for example, the noise output can rise to unacceptable levels.
SUMMARY OF THE INVENTION
The present invention features a technique that utilizes an active heat sink which may be combined with a variety of components or incorporated in a variety of devices. The technique utilizes a fan, such as a blower fan, in a manner that promotes a high velocity airflow across a heat sink. In one example, a blower fan is combined with a heat sink such that the heat sink acts as what would otherwise be the base of the blower housing. Thus, the heat sink is positioned generally at the area of highest air velocity in the blower fan prior to experiencing a reduction in velocity when the air is expelled from the blower fan housing. This embodiment and others can be combined with a variety of components, such as processors or other heat generating devices, that are utilized in many types of products.


REFERENCES:
patent: 5309983 (1994-05-01), Bailey
patent: 6047765 (2000-04-01), Zhan

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