The invention relates to a thermal management system for a multiple processor computer appliance. More particularly, the present invention enables cool ambient air to absorb heat generated by multiple processors, or other electronic devices, without loss of cooling efficiency while minimizing the amount of space needed for the cooling system.
In the rapid development of computers many advancements have been seen in the areas of processor speed, throughput, communications, and fault tolerance. Initially computer systems were standalone devices in which a processor, memory and peripheral devices all communicated through a single bus. Later, in order to improve performance, several processors were interconnected to memory and peripherals using one or more buses. Today computer components have become so small that multiple high-performance processors, memory and disk drives, as well as other equipment, may all be placed on a single baseboard or circuit board. However, computer equipment in general and microprocessors in particular have always been susceptible to damage due to heat buildup.
Several methods have been employed for cooling high-performance microprocessors. A common method of cooling such microprocessors uses a fan heat sink in which an axial fan is attached to the heat sink atop the microprocessor in order to blow air across the heat sink to remove the heat dissipated by the microprocessor. However, these types of fan heat sinks are not that effective and generate their own sets of problems. First, they significantly increased the height of the baseboard or circuit board. Second, they are not effective cooling methods since the ambient air surrounding a microprocessor may be heated by surrounding components on the circuit board.
Another method of cooling high-performance microprocessors may be found in U.S. Pat. No. 5,912,802 to Nelson. FIG. 1 is a block diagram of the cooling system 100 as shown in the Nelson patent. The cooling system 100 has a blower 110, a first air duct 120, a first ducted heat sink 130, a second air duct 140, and a second ducted heat sink 150. The blower 110 brings in ambient air from air intake 135. The blower 110 forces air through the first air duct over the first ducted heat sink 130 which is attached to first microprocessor 160. The air moving over the first ducted heat sink 130 absorbs the dissipated heat from the first microprocessor 160 and continues through the second air duct 140. Thereafter, this warmer than ambient air passes through the second ducted heat sink 150 where it further absorbs heat dissipated from the second microprocessor 170.
It should be noted in the Nelson cooling system that the air ducts are connected in series and as the air passes over successive heat sinks attached to microprocessors it eventually would reach a temperature where cooling would be ineffective. The second microprocessor""s heat sink receives pre-heated air from the first microprocessor""s heat sink. Hence the second microprocessor would be inadequately cooled. In order for such a serial cooling system to handle several processors or extremely high-performance processors it is necessary to increase the size of blower 110 as well as the size of the air intake 135 and the first and second air ducts 120 and 130.
Therefore, what is required is a mechanism via which cool ambient air may be brought into contact with each heat exchanger for each microprocessor. This mechanism should not use air supplied to a microprocessor that has been pre-heated by a previous device. Further, the size of the blower as well as the air ducts should be kept to an absolute minimum so as to conserve power and space required by a computer appliance. Still further, the entire computer including processors, disk drives as well as the heat sinks and cooling system must fit within a 1U industry standard height which is 1.75 inches. In addition, this mechanism must be able to be adjusted so that depending upon the heat generated the appropriate volume of cooling air may be passed over the heat sink.