Abstract:
Liquid cooling is selectively enabled at a portable information handling system to provide enhanced processing capabilities when needed or desired. A liquid cooling cold plate conducts thermal energy from a processing component heat pipe or heat sink to a liquid pumped from external to the information handling system housing. The pump operates with power provided from an AC/DC adapter of the information handling system or power provided from an interface with the information handling system, such as a USB port and cable. Alternatively, liquid cooling is included in a cradle to automatically engage with the information handling system is coupled to the cradle.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to the field of information handling system cooling, and more particularly to dual mode portable information handling system cooling. 
     2. Description of the Related Art 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
     Information handling systems provide a wide range of performance capabilities based upon the type of components included in the system. For example, processing capability depends upon the number of instructions that a processor can execute in a given time period. To make effective use of a powerful processor, the system typically needs a sufficient quantity of RAM for storing instructions and high capacity links to communicate information between the processor and desired components. In some instances, processor performance is enhanced by moving processing functions from a central processor unit (CPU) to supporting processors. For example, a graphics processor unit (GPU) executes instructions under the direction of a CPU to generate images for presentation at a display. In general, more powerful information handling systems have a larger housing to hold components. A larger-sized housing typically allows more room for the components and for supporting equipment, such as cooling fans. Typically, more powerful processing components tend to have greater amounts of heat generated as a by-product of processing instructions. The heat is removed by heat sinks and cooling fans that blow air over the components and out of the housing. A larger-sized housing provides more room for heat transfer devices and cooling airflow. In some instances, cooling is accomplished by passing a contained liquid flow proximate the heat-generating component since liquid typically provides a more efficient heat transfer medium than air. 
     Difficulties with heat transfer tend to increase as the size of an information handling system housing decreases. Portable information handling systems generally have relatively small housings so that an end user can hold the system during use. Portable information handling systems typically incorporate an integrated display and battery power source so that an end user can operate the system free from any external interfaces. In order to reduce system size and weight, components are often selected to build portable information handling systems so that heat generation and power consumption by the components fall within tight constraints. As a result, portable information handling systems typically have reduced processing capabilities relative to desktop or tower systems. Further, portable information handling systems often include power and cooling system logic that attempts to alter system operations to extend battery life and avoid overheating. One example of a way to avoid excessive power consumption and heat generation is to run a processor at a reduced speed, however, running a processor at reduced speed also reduces system performance. An end user may find reduced performance acceptable for some functions, such as word processing, however other functions often need full system performance to provide meaningful use to an end user, such as for gaming. In any event, the capability of a processor included with a portable information handling system is limited by the ability of the system to remove excess heat generated by the processor, which in turn is for practical purposes generally limited by the size of the housing. 
     SUMMARY OF THE INVENTION 
     Therefore a need has arisen for a system and method which supports dual mode portable information handling system cooling. 
     In accordance with the present invention, a system and method are provided which substantially reduce the disadvantages and problems associated with previous methods and systems for cooling a portable information handling system. Liquid cooling is selectively applied at a heat transfer device within an information handling system to supplement cooling otherwise available, such as passive cooling or cooling provided by airflow from a fan. When liquid cooling is available, processing components having the supplement cooling can operate at greater speeds since excess heat created by the greater operating speeds is removed by the liquid cooling. When liquid cooling is not available, processing components operate in a throttled condition as needed to maintain thermal constraints. 
     More specifically, a portable information handling system housing contains processing components that cooperate to process information, a display to present information and a battery to power the processing components and display. A cooling fan generates cooling airflow across a thermal transfer device, such as heat sink or heat pipe, to remove thermal energy generated as a by-product of the operation of one or more processing components. A cold plate disposed in the housing proximate the thermal transfer device accepts thermal energy from the thermal transfer device to liquid of a liquid cooling device. The liquid cooling device liquid removes thermal energy to the environment external to the housing with a pump and radiator disposed external to the housing. The liquid cooling device is selectively removable from information handling system  10 , such as by disconnecting tubes of the liquid cooling system from the housing or removing the cold plate from the housing. When liquid cooling is available, processing components can operate at greater speeds that generate excess heat with the liquid cooling supplementing other cooling available at the information handling system. When liquid cooling is not available, processing components within the information handling system operate at throttled speeds to prevent overheating. 
     The present invention provides a number of important technical advantages. One example of an important technical advantage is that a portable information handling system includes selectively-activated processor liquid cooling that will allow powerful processors to operate at high speeds with minimal impact on housing size. An external liquid pump conveniently adds system cooling when desired in both a portable and fixed configuration. For example, including a liquid pump with an AC-DC adapter provides ready availability when operating on external power while a USB interface provides power for liquid pumping when operating on internal power. Alternatively, including liquid cooling with a housing cradle supports full system capabilities when in a fixed configuration that are not otherwise available in portable systems due to limitations of air cooling. A removable cooling plate that couples and decouples proximate to a heat sink or heat pipe maintains liquid cooling fluids in a separate integrated system for ready use with limited risk of spilling the fluid. When liquid cooling is unavailable, the processor or other heat-generating device continues to operate at a lower capability within the limits of air cooling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element. 
         FIG. 1  depicts an information handling system in a portable housing having a selectively removable liquid cooling system interfaced with a processor heat transfer device; 
         FIG. 2  depicts a liquid cooling system cold plate affixed to a heat pipe; 
         FIG. 3  depicts a portable information handling system aligned to receive liquid cooling from a docking station cradle; and 
         FIG. 4  depicts an external liquid cooling pump powered by an external information handling system AC/DC adapter or a USB connection with the information handling system. 
     
    
    
     DETAILED DESCRIPTION 
     Selective configuration of liquid cooling at a portable information handling system supports enhanced processing capability when liquid cooling is available and light weight portability when liquid cooling is removed. For purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components. 
     Referring now to  FIG. 1 , an information handling system  10  in a portable housing  12  has a selectively removable liquid cooling system  14  interfaced with a processor heat transfer device  16 . Information handling system  10  includes plural processing components that cooperate to process information, such as a central processing unit (CPU)  18 , RAM  20 , hard disk drive  22 , chipset  24  and graphics processing unit (GPU)  26 . Information handling system  10  has a portable configuration that allows operation without external devices, such as with an integrated display  28  for presenting information as visual images and a battery  30  for powering the processing components. During portable operations, a power manager  32  directs battery  30  to power components. If external power is available, an external AC/DC adapter  34  provides power to the components and to charge battery  30 . A fan  36  disposed within housing  12  generates a cooling airflow past the processing components and heat transfer device  16  to carry heat through a vent  38  and out of housing  12 . 
     Removable liquid cooling system  14  selectively interfaces cooling liquid with heat transfer device  16  to provide additional cooling for the processing components, such as CPU  18 . For example, a pump  40  draws a water glycol mixture from information handling system  10  through an exhaust tube  42  to a radiator  44 , which transfers heat from the liquid to the atmosphere external to information handling system  10 , such as with a fan in radiator  44  that blows cooling past heat transfer portions in radiator  44 . Pump  40  then draws cooled liquid from radiator  44  through a transfer tube  46  and provides the cooled liquid through an intake tube  48  back to information handling system  10 . Intake tube  48  and exhaust tube  42  selectively interface through connectors  50  to a cold plate  52  disposed within housing  12 . When connectors  50  couple to cold plate  52 , liquid from pump  40  is in fluid communication with cold plate  52  to aid in cooling heat transfer device  16 . When connectors  50  decouple from cold plate  52 , liquid is not available for cooling heat transfer device  16  so that cooling is accomplished by fan  36  without the aid of liquid cooling. A thermal manager  54  monitors temperatures within housing  12  and at the processing components to ensure that thermal constraints are not exceeded. For example, without the availability of liquid cooling, thermal manager  54  constrains the operating speed of CPU  18  to prevent the generation of excess thermal energy and run fan  36  at higher speeds; with the availability of liquid cooling thermal manager  54  allows operation of CPU  18  at full speed and minimizes the speed of fan  36  to reduce power consumption and noise. In alternative embodiments, other processing components, such as GPU  26 , are cooled with liquid cooling or throttled in the absence of liquid cooling. In one embodiment, CPU  18  is designed to require liquid cooling in order to operate at full speed, such as to support gaming applications, with a throttled state to provide minimal functionality without liquid cooling, such as to support word processing or web browsing activities. 
     In the example embodiment depicted by  FIG. 1 , pump  40  and a fan in radiator  44  obtain power from a selected of plural power sources. Power may come from an external power source  56 , such as an AC outlet. Alternatively, AC/DC adapter  34  that provides power to information handling system  10  can also provide power to pump  40 . As a third alternative, power is provided from battery  30  of information handling system  10  through an external interface, such as a USB ports  58  located at housing  12  and pump  40  and a USB cable  60 . In most circumstances, a constant speed pump  40  provides adequate liquid flow for cooling across the operational thermal range of information handling system  10 . In an alternative embodiment, the speed or operation of pump  40  is managed through communication across USB cable  60 . For example, pump  40  is operated at a slow speed or intermittently to maintain a desired thermal condition at heat transfer device  16  while reducing noise and power consumption. 
     Referring now to  FIG. 2 , a liquid cooling system cold plate  52  is affixed to a heat pipe  62 . Heat pipe  62  provides a thermal conduction path from processor  18  to a radiator  19  disposed in a cooling airflow generated by fan disposed beneath radiator  19 . Processor  18  is disposed beneath a heat sink  64  that spreads heat generated by processor  18  to the heat pipes  62 . Cooling plate  52  is affixed to heat pipe  62  in a permanent fashion, such as with solder or screws, so that high thermal conduction is available from heat pipe  62  to liquid disposed in cold plate  52 . Liquid cooling is applied to cold plate  52  by selectively engaging liquid or disengaging liquid with a sealed connection accessible at the housing of information handling system  12 . In alternative embodiments, cold plate  52  may include an attachment device that selective attaches and detaches with a thermally-conductive material that is in thermal connection with a cooling liquid. Affixing cold plate  52  in a permanent manner provides optimal thermal conduction, however, removable coupling and de-coupling of cold plate  52  or a portion of cold plate  52  to heat pipe  62  provides adequate thermal conduction with the advantage of keeping cooling liquid within a contained environment without having to rely on sealed connectors. 
     Referring now to  FIG. 3 , a portable information handling system is aligned to receive liquid cooling from a docking station cradle  66 . Docking station cradle  66  has a connector  68  to support power and peripheral interactions with information handling system  10  as with a conventional cradle, however, includes a cold plate  52  aligned to insert into an opening  70  formed in the bottom surface of information handling system  10 . Cold plate  52  is in liquid communication with pump  40  and radiator  44  of cradle  66  so that liquid cooling is available through cold plate  52  to a heat sink  16  or other heat transfer device within the housing  12  of information handling system  10 . Opening  70  is selectively closed when information handling system  10  is removed from cradle  66  to prevent end user interaction with heated internal components of information handling system  10 . When docked at cradle  66  with liquid cooling provided by cold plate  52  to heat sink  16 , information handling system can operate with increased processing speeds because excess thermal energy is removed from housing  12  with liquid cooling. When undocked so that liquid cooling is not available, a fan  36  provides cooling adequate to support operations with lower processor speeds. 
     Referring now to  FIG. 4 , an external liquid cooling pump  40  is powered by an external information handling system AC/DC adapter  34  or a USB connection  58  with the information handling system  10 . AC/DC adapter  34 , pump  40  and radiator  44  are coupled together in a contiguous piece for ease of operation. In an alternative embodiment, AC/DC adapter  34  selectively separates from pump  40  to provide power without liquid cooling. Cold plate  52  inserts into a side opening  72  of housing  12  to a position proximate a heat transfer device within housing  12 . Although a removable cold plate may not provide as much thermal conduction as a cold plate that is affixed within housing  12 , a biasing mechanism within housing  12  provides adequate physical contact between removable cold plate  52  and the internal heat transfer device so that thermal conduction between the internal heat transfer device and liquid associated with cold plate  52  takes place. Having cold plate  52  as a removable component allows liquid to remain in a contained environment to help reduce the risk of inadvertent leaks that might damage electronic components. 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the appended claims.