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DYNAMIC FLUID SPRAYJET DELIVERY
SYSTEM
The present invention relates generally to cooling systems for heat-generating devices and, more particularly, to a 5 dynamic cooling fluid delivery system and a method of dynamically delivering cooling fluid to cool one or more hot components.
BACKGROUND OF THE INVENTION 1°
With the advent of semiconductor devices having increasingly large component densities, the removal of heat generated by these devices has become an increasingly challenging technical issue. Highly available computer systems, 15 to prolong a customer's investment, are designed to both be maintained for long periods and to be easily maintained over time. This makes it preferable that a computer system is well cooled across all of its components on each board, and that the computer can quickly and readily accept replacements 20 for malfunctioning boards. Typical processor boards sometimes include multiple CPU modules, application-specific integrated circuits, and one or more types of memory such as static random access memory, as well as dc-dc converters, all of which have different and extreme power dissipation 25 requirements. Adding to the complexity, the variety of chip types on typical processor boards provides for chip surfaces at a variety of heights off the board's surface.
In the past, the low power dissipation of the processors 3Q accommodated the use of low cost, air-cooled heat sinks that require minimal re-design effort. However, with higher dissipation requirements comes more complex cooling systems that make both the even cooling requirements and the serviceability of a board a more complex issue. In particular, 35 different components stand up off the board with different heights, which causes board-wide cooling systems to cool different components to different degrees, even if the components' power dissipation levels are similar, which typically is not the case.
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Spray-cooling technologies can offer high dissipation levels that meet extreme cooling requirements. With reference to FIG. 1, in spray cooling, an inert spray coolant from a reservoir 11 is preferably sprayed by sprayers 13 onto chips 15 mounted on a printed circuit board 17. The coolant 45 preferably evaporates, dissipating heat within the chip. The sprayers and chips, and the board, are mounted within sealed cases 19 fixed within a computer system. The sprayed coolant is typically gathered and cooled within a condenser 21, and then routed back to the reservoir by a pump 23. 5Q
The cases are evacuated systems with robust closure systems. Access to the components for maintenance can typically be had only through extensive disassembly of the computer system and case, which is significantly more time consuming and costly than the maintenance of standard 55 air-cooled chips. Thus, for a liquid cooled board, board replacement becomes a complex issue that must deal with the presence of liquid, and potentially the need for an evacuated system.
Additionally, the repair or replacement of the cooling 60 system, which includes a multitude of sprayers, can be time consuming and expensive. To minimize computer down time when a sprayer fails to function properly, a complete replacement of the cooling system can be used. However, the costs of such a replacement can be high because a 65 number of functional sprayers that must be discarded with the dysfunctional sprayer.
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Furthermore, it is known that the thermal performance achieved from spray cooling is dependant upon the distance between the firing nozzle and the hot surface. A greater distance allows for more of the cooling fluid to evaporate prior to reaching the chip. Furthermore, drag reduces the speed of the droplets, allowing even more cooling fluid to evaporate prior to reaching the chip. The evaporation of cooling fluid prior to reaching the chip reduces the fluid flow rate received by the chip, and thus reduces the thermal performance of the spray-cooling system. The reduced speed of the droplets also reduces their momentum, and thus their ability to penetrate vapor barriers, such as can form at near-maximum levels of heat flux for a spray-cooling system.
Since processor boards can and often do contain components of dissimilar heights, it has been suggested that the hottest component be used as the reference component to determine the sprayjet cartridge-to-board spacing. The primary disadvantage of this technique is that fluid may be delivered inefficiently to other hot components of markedly different heights from the reference component.
Accordingly, there has existed a need for an easily maintainable spray-cooling system that maximizes spray-cooling efficiency for a plurality of components on a printed circuit board, while minimizing system cost. Preferred embodiments of the present invention satisfy these and other needs, and provide further related advantages.
SUMMARY OF THE INVENTION
In various embodiments, the present invention solves some or all of the needs mentioned above by providing a cooling system that efficiently operates on one or possibly more high-dissipation devices.
The invention can typically be a delivery system for delivering cooling fluid to cool a hot component on a board. The component has a designated spray-location, which might vary depending on the sprayer to be used. The invention features a spray-module and an actuator. The spray-module includes a sprayer configured for delivering cooling fluid to cool the component when the spray-module is located in the designated spray-location. The actuator is configured to actuate through a plurality of actuator positions that (relatively) position the spray-module at a plurality of lateral locations with respect to the board. One of the plurality of lateral locations is the designated spray-location.
Optionally, the invention might be further configured for delivering cooling fluid to cool a second hot component on the board, the second component having a second designated spray-location. The second designated spray-location might be one of the first plurality of lateral locations. Alternatively, the invention might feature a second spraymodule and a second actuator. The second spray-module includes a second sprayer configured for delivering cooling fluid to cool the second component when the second spraymodule is located in the second designated spray-location. The second actuator is then configured to actuate through a second plurality of actuator positions that (relatively) position the second spray-module at a second plurality of lateral locations with respect to the board, one of the second plurality of lateral locations being the second designated spray-location;
Advantageously, such features might be adapted to allow for actuation of the spray-module from the designated spray-location to a lateral location that is safe for inserting and removing the board. Likewise, such features might be adapted to provide for the spray cooling of a multitude of
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components with only a limited number of actuators and sprayers, thus minimizing both the cost of the spray-modules and the number of spray-modules that might fail.
The invention can further feature a controller configured to control the delivery of cooling fluid by each sprayer, to 5 cool the plurality of components. In doing so, the controller might control the operation of the actuator to control the delivery of cooling fluid by the sprayer (e.g., by controlling the cooling times), or the controller might control the operation of the spray-modules to control the delivery of 10 cooling fluid by the sprayer (e.g., by controlling cooling fluid spray rates). The controller might also control a heightactuator configured to control the spraying height of the sprayers above the components, the use of a spray-module station to refill reservoirs in the spray-modules, and/or a 15 configuration system configured to adapt embodiments of the invention for use with different pluralities of lateral locations, and thus for different designated spray-locations.
These additional features typically provide for spray cooling with a high degree of control over an efficient 20 cooling process. The refillable reservoirs and configuration system typically allow for embodiments of the invention to accommodate a wide range of board layout variation.
The invention can further feature one or more sensors configured to sense cooling-status information. The control- 25 ler is configured to control the delivery of cooling fluid by the sprayers to cool the components, based on the coolingstatus information sensed by the sensors. Advantageously, this feature typically provides for the highly controlled cooling process to be quickly and accurately responsive to 30 the changing cooling status of the components.
Other features and advantages of the invention will become apparent from the following detailed description of the preferred embodiments, taken with the accompanying drawings, which illustrate, by way of example, the prin- 35 ciples of the invention. The detailed description of particular preferred embodiments, as set out below to enable one to build and use an embodiment of the invention, are not intended to limit the enumerated claims, but rather, they are intended to serve as particular examples of the claimed 40 invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a system layout of a prior art spray-cooling 45 system.
FIG. 2 is a perspective view of a first modular board connection system embodying the invention, and a printed circuit board. ^
FIG. 3 is a top cross-sectional view of the first modular board connection system and the printed circuit board, as depicted in FIG. 2, the first modular board connection including a sprayer delivery system.
FIG. 4 is a front view of a first actuator and a first 55 spray-module spraying a printed circuit board, the first actuator being part of the sprayer delivery system, as depicted in FIG. 2.
FIG. 5 is a cross-sectional view of two ink-jet type nozzles as used in the first modular connection system 60 depicted in FIG. 2.
FIG. 6 is a side view of a sprayer delivery system and spray-modules spraying a printed circuit board, the sprayer delivery system and spray-modules being part of a second modular board connection system embodying the invention. 65
FIG. 7 is a side view of a sprayer delivery system and a spray-module spraying a printed circuit board, the sprayer
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delivery system and spray-module being part of a third modular board connection system embodying the invention.
FIG. 8 is a side view of a sprayer delivery system and a spray-module spraying a printed circuit board, the sprayer delivery system and spray-module being part of a fourth modular board connection system embodying the invention.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENTS
The invention summarized above and defined by the enumerated claims may be better understood by referring to the following detailed description, which should be read with the accompanying drawings. This detailed description of particular preferred embodiments of the invention, set out below to enable one to build and use particular implementations of the invention, is not intended to limit the enumerated claims, but rather it is intended to provide particular examples of them.
With reference to FIGS. 2 through 4, a first preferred embodiment of the invention resides in a sprayer delivery system, a related board connection system, a related spraycooling system, and in related methods. One or more board connection systems of this embodiment can be installed as part of an electronic device (not shown), such as a computer system, to provide for the use of spray cooled printed circuit boards that can be quickly and easily serviced and replaced, or upgraded.
The board connection system is designed to removably contain a printed circuit board 101 carrying one or more heat-producing components 103 such as semiconductor chips, including a hot (and typically heat-producing) first component 103A, and preferably a hot (and typically heatproducing) second component 103B and a hot (and typically heat-producing) third component 103C. The board connection system includes apparatus for spray cooling the chips with a cooling fluid while the chips are hot and in operation. The electronic device is preferably configured for the efficient replacement of the board, potentially without shutting down. Thus, the invention allows for hot-pluggable replacement boards that are spray cooled.
More particularly, this embodiment of the board connection system includes an enclosure 105, an electrical connector 107, the sprayer delivery system, and a plurality of spray-modules 109 including a first spray-module 109 A, a second spray-module 109B, and preferably one or more additional spray-modules, each spray-module having one or more sprayers. The enclosure defines an internal chamber 111, the chamber being configured to contain the board, the sprayer delivery system, and the spray-modules.
A door 113 of the chamber can be readily opened and closed, such as by hand, for external access to the chamber. This access allows printed circuit boards to be removed and replaced while the chamber is opened. When the chamber is closed, it is sealed such that cooling fluid cannot leak from the chamber, and can only enter or exit the chamber through an inlet port 115 and an outlet port 117. Preferably, the seal created by the door 113 is adequate to allow the chamber 111 to be evacuated. The electrical connector is configured to electrically connect the electronic device to the inserted printed circuit board via a ribbon cable 119, enabling the operation of the one or more chips.
The spray-modules 109 are located within the chamber 111, and each of their sprayers is preferably configured to spray cooling fluid toward one or more of the components 103 while the components are hot, such as during the components' operation. More particularly, the sprayer deliv
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