Kinetic heat sink having controllable thermal gap

Abstract

An apparatus and method for cooling a heat-generating component includes a stationary base structure and a rotating structure. The stationary base structure is mountable at the first heat-conducting surface to or near the heat-generating component. The stationary base structure has a first and second heat-conducting surface to conduct heat therebetween. The rotating structure is rotatably coupled to the stationary base structure. The rotating structure has a heat-extraction surface facing the second heat-conducting surface across a spatial gap. As a result of the rotating structure rotatably moving, the rotating structure substantially transfers the heat from the second heat-conducting surface to a thermal reservoir communicating with the rotating structure. In addition, as a result of the rotating structure rotatably moving, at least two surfaces of the rotating structure and/or the stationary base structure generate a thrust and an opposing thrust to vary and/or maintain the spatial gap.

What is claimed is: 
     
         1 . A kinetic heat sink apparatus comprising:
 a stationary member comprising a base structure having a first heat-conducting surface and a second heat-conducting surface to conduct heat therebetween, the base structure being fixably mountable at the first heat-conducting surface to a heat-generating component; and   a rotating structure rotatably coupled with the base structure, the rotating structure having a movable heat-extraction surface facing the second heat-conducting surface across a spatial gap, the rotating structure being configured to transfer heat from the second heat-conducting surface to a thermal reservoir communicating with the rotating structure,   the rotating structure and stationary member including two pairs of opposing surfaces, at least one surface of each of the two pairs of opposing surfaces having hydrodynamic features thereon, the two pairs of opposing surfaces of the rotating structure and the stationary base structure producing respective first and second thrust bearings to maintain the spatial gap within a pre-specified range during the rotation of the rotating structure.   
     
     
         2 . The apparatus of  claim 1 ,
 wherein the stationary member includes a stationary motor member, the rotating structure includes a rotating motor member, the stationary motor member and rotating motor member forming a motor assembly configured to rotate the rotating structure when energized,   the stationary motor component and the rotating motor component include at least one of the two pairs of opposing surfaces to generate at least one of the two thrusts in opposing direction during the rotation of the rotating structure.   
     
     
         3 . The apparatus of  claim 2 , wherein the stationary member includes a heat insulating portion between the stationary motor member and the base structure to thermally insulate the stationary motor member. 
     
     
         4 . The apparatus of  claim 2 , wherein at least one of the stationary motor member and the rotating motor member includes channels to direct cooling fluid therethrough. 
     
     
         5 . The apparatus of  claim 1 , wherein at least a portion of the heat-extraction surface and at least a portion of the second heat-conducting surface form one of the two pairs of opposing surfaces to generate one the two thrusts in opposing direction during the rotation of the rotating structure. 
     
     
         6 . The apparatus of  claim 1 , wherein the rotating structure includes a shaft portion including at least two surfaces, each of the two surfaces of the shaft portion being a part of each of the two pairs of opposing surfaces,
 the stationary member including two corresponding surfaces facing the two surfaces of the shaft portion, each of the two corresponding surfaces of the stationary member being a corresponding part of each of the two pairs of opposing surfaces, the two surfaces of the shaft portion and the two corresponding surfaces of the stationary member generating the two thrust bearings during the rotation of the rotating structure.   
     
     
         7 . The apparatus of  claim 1 , wherein each pair of the at least two pairs of opposing surfaces form a hydrodynamic bearing, the hydrodynamic bearing including at least one member of the group consisting of a spiral groove bearing, a step bearing, a sector step bearing, a Rayleigh step bearing, a thrust inward-pumping bearing, a thrust outward-pumping bearing, and a herringbone thrust bearing. 
     
     
         8 . The apparatus of  claim 1 , wherein the rotating structure includes a plurality of flow-directing members to channel ambient fluid to dissipate heat from the rotating structure, the flow-directing members including at least one member of the group consisting of fins and fan blades. 
     
     
         9 . The apparatus of  claim 1 , wherein the spatial gap varies between approximately 10 and 20 micrometers during the rotation of the rotating structure. 
     
     
         10 . The apparatus of  claim 1 , wherein the base structure and the rotating structure are comprised of different thermal conducting materials. 
     
     
         11 . The apparatus of  claim 1  further comprising:
 a sensor configured to generate a feedback signal associated with at least one of 1) the distance of the spatial gap and 2) a thermal quantity associated with at least one of the heat-generating component, the base structure, and the rotating structure; and 
 a controller configured to vary a speed of rotation of the rotating structure based on the feedback signal. 
 
     
     
         12 . The apparatus of  claim 1  further comprising:
 an active pump regulator configured to introduce fluid into the spatial gap. 
 
     
     
         13 . The apparatus of  claim 1  further comprising:
 a spatial gap regulator configured actively vary the spatial gap based on an electromagnetic field. 
 
     
     
         14 . The apparatus of  claim 1 , wherein at least one of the base structure and rotating structure includes a coating having a coefficient of friction less than 0.5, the base structure and rotating structure being in contact at the coating when the rotating structure is at rest. 
     
     
         15 . The apparatus of  claim 1 , wherein at least one of the base structure and rotating structure includes an insert that separates a portion of the heat-extraction surface from a portion of the second-heat conducting surface when the rotating structure is at rest. 
     
     
         16 . The apparatus of  claim 1 , wherein the base structure forms, in part, at least one of a vapor chamber, a motor, and a heat pipe. 
     
     
         17 . A kinetic heat sink comprising:
 a base plate adapted to fixably mount to a heat-generating component;   an impeller configured to rotate in relation to the base plate across a gap of less than 20 micrometers, the impeller having an impeller plate and a plurality of fins extending therefrom, the impeller plate forming the gap with the base plate, the fins forming channels therebetween; and   a spindle motor configured to cause the impeller to rotate, the spindle motor having a stationary portion affixed to the base plate and a rotating portion affixed to the impeller,   at least two portions of the stationary and rotating portions of the spindle motor forming fluid-dynamic bearings,   during the rotation of the impeller, the base plate conductively receiving heat from the heat-generating component and transferring at least a portion of the received heat across the gap to the impeller, the gap being regulated, at least in part, by thrusts formed in opposing directions by the fluid-dynamic bearings, the impeller receiving the transferred heat and transferring the transferred heat to ambient fluid communicating with the impeller by directing the ambient fluid through the channels.   
     
     
         18 . A method of dissipating heat from an electronic device, the method comprising:
 providing a stationary structure having a first and second heat-conducting surface, the stationary structure being thermally coupled to the electronic device at the first heat-conducting surface to draw heat from the electronic device, the stationary structure conducting the drawn heat from the first heat-conducting surface to the second heat-conducting surface;   rotating a rotating structure having a heat-extraction surface facing the second heat-conducting surface across a spatial gap, rotating transferring heat from the second heat-conducting surface to the rotating structure and rejecting the transferred heat from the rotating structure to a thermal reservoir in communication with the rotating structure; and   generating thrusts on the rotating structure as a result of the rotation of the rotating structure, at least two of the thrusts being in opposing directions to maintain the spatial gap within a pre-specified range.   
     
     
         19 . The method of  claim 18  further comprising:
 varying the rotation of the rotating structure, including a rate of rotation, to maintain the spatial gap within a pre-specified range. 
 
     
     
         20 . The method of  claim 19  further comprising:
 measuring a thermal quantity associated with at least one of the stationary structure, the stationary structure, the spatial gap, and the electronic device; and 
 using the measured thermal quantity to vary the rotation of the rotating structure.